Title of Invention	"A DEVICE USEFUL FOR HARVESTING/ RIDGING OF SALT/SOIL"
Abstract	The present invention provides a device useful for harvesting/ridging of salt or soil. The device of the present invention is capable of extending the scraping and conveying function for a long horizontal distance, using a mobile power source from outside the pan, which helps in conveying predominant ridger device to do the job of transporter. Further the invention also facilitates to dump the ridged material into an integrated container placed above the mobile power source (tractor etc.), having hydraulic hauling advantages used intermittently, and thereby performing scraping, conveying, lifting and hauling the ridge of salt/soil.

Title of Invention

"A DEVICE USEFUL FOR HARVESTING/ RIDGING OF SALT/SOIL"

Abstract

The present invention provides a device useful for harvesting/ridging of salt or soil. The device of the present invention is capable of extending the scraping and conveying function for a long horizontal distance, using a mobile power source from outside the pan, which helps in conveying predominant ridger device to do the job of transporter. Further the invention also facilitates to dump the ridged material into an integrated container placed above the mobile power source (tractor etc.), having hydraulic hauling advantages used intermittently, and thereby performing scraping, conveying, lifting and hauling the ridge of salt/soil.

Full Text	The present invention relates to a device useful for harvesting/ridging of salt/soil. The device of the present invention may be used in conjunction with a prime-mover such as a tractor (the first selected source of mobile power designed to work in agricultural farm, and utilised here for salt/soil layer fractioning, cutting, scraping, loosening, scarifying, chopping, raking and ridge formation along with material haulage) for salt farming work. The main usage of the device of the present invention is in the salt farm to scrap the salt layer of uniform thickness, accumulate and convey or transfer the same simultaneously upto the bund of the pan in the form of salt ridges (the linear formation of heaps along with the path of the tractor travelling). Similarly soil ridges are also formed by scraping salt farm soil to the required pan dimensions of its length and breadth. Basically harvesting of salt consists of removing the crystals from the localtion of precipitation. Harvesting is a major factor in the cost of salt production. The handling problem represents an important factor in the cost of salt. Salt is always found in spreaded form on flat land, having poor traffic possibilities called the crystallizer pan bed, particularly in all the middle size salt works of India, where the evaporation of salty water is taking place through the utilisation of cheapest natural source of solar and wind energy. Till now crystallised salt is collected manually almost everywhere in India and elsewhere in medium size salt works, producing minimum ten thousand tons of salt per year. The use of the device of the present invention is possible only when the bearing strength of the bed is capable enough to permit the operation of the ridger without damaging the bed i.e. pan bottom or spoiling the quality of salt, by an addition of clay/mud in the product. Here the tread pressure of the wheels due to the weight of the tractor mounted ridger is considered balancing against the effective strength of the salt layer. The conventional heavy mechanical salt harvesters are applicable to large salt works where scraping, lifting and dumping works are performed together in a big way. The technical field of the present work is classified as: Salt Works Engineering, Material Handling, Production Engineering, Mechanical Engineering & Agricultural Engineering. Presently there are several equipments/devices which are known for salt harvesting. The working actions of all the known salt harvesters can be divided into two types. The first and main action is to scrap the raked or unraked layer of crystallised salt. The second and subsidiary action is to elevate, dump and transport the same to a long distance or simply transfer the same salt by dragging it to a limited internal distance of pan without lifting it all through. Mostly prior salt harvesters follow scraping, lifting, plus dumping and transferring, whereas the design of the present invention advocates for scraping and dragging the same salt without lifting it all through. In Fig.l of the drawings is shown a schematic diagram of a "Semi-mechanised salt harvester" by R.P.Dhiman, R.V.Bhatt, D.S.Datar & R.L.Dutta of Central Salt and Marine Chemicals Research Institute, Bhavnagar, constituent laboratory of Council of Scientific and Industrial Research, published in Salt Research & Industry, Vol.2, No.3, July 1965, p. 111. The maximum working capacity (1) of the design is 10 tons per hour. The weight of the harvester is 230 kg. It exerts pressure on bed (2) of about 0.35 kg per sq.cm. An inclined 0.66 m [2 ft] wide blade (3) carrying conveyor (4) is pulled forward manually (5) to scrap the raked salt layer. The conveyor dumps the salt into trailer (6) or into the van moving behind the harvester. The drawbacks of the above noted "Semi-mechanised salt harvester" are given below: Two workers were pulling the harvester with their hands held on the backsides. The pull was found limited to run the harvester continuously for one hour. In Fig.2 of the drawings is shown a schematic diagram of a "Mechanical salt harvester for Indian Salt Works ". A report by R.P.Dhiman and A.S.Kane of Central Salt & Marine Chemicals Research Institute, Bhavnagar, constituent laboratory of Council of Scientific & Industrial Research. The design consists 60 cm. wide steel blade (7) which cuts a layer of salt while moving forward which is then lifted up by a belt conveyor (8) that dumps into a trailer through a chute (9). The harvester is powered with a 6 kw air cooled engine (10). It has a salt harvesting capacity of 5 tons per hour (11). It is suitable for small salt works of upto 10,000 tons per year production capacity. The attached trailer (12) has 1 ton hauling capacity. Salt accumulation was taking place in front of the blade. The drawbacks of the above noted "Mechanical Salt harvester for Indian Salt Works " are given below: The hauling problem of 5 trailers per hour was required to be managed. The traffic frequency and the salt bed conditions were not made for each other. This self powered design had inherent mechanical power transmission problems. It could not harvest one pan worth salt. In Fig.3 of the drawings is shown a schematic diagram of a "Mechanical salt harvester for Indian Salt Works". A report by R.P.Dhiman and Dr.A.S.Kane of Central Salt & Marine Chemicals Research Institute, Bhavnagar, constituent laboratory of Council of Scientific & Industrial Research and Mechanical Salt Harvester by R.P.Dhiman, published in Salt Research & Industry, Vol.5, NO.3&4, July-Oct, 1968,p.81. It is a mechanical salt harvester SD-2A, a compact apparatus for cutting, lifting and washing of salt from the crystalliser. The harvester has 10-15 tons per hour capacity (13). It consists essentially of two conveyors, the lower one (14) which is carried in a frame, which can be raised when not required for harvesting or lowered for harvesting of salt as required. At the lower end of the frame is a special 60 cm. wide steel blade (15) which can be lowered down into the salt by means of screwed lever mechanism when the harvester moves forward, thus cutting an accurately controlled layer of salt which is lifted up into an accumulator (16) where the salt gets drained, from which the upper conveyor (17) lifts it to a height of about two meters above salt bed and dumps salt into a trailer (19) attached behind the harvester through a chute (18). The harvester is powered by a 11 kw self start engine (20) which drives the harvester as well as the conveyors and trailer at different selective speeds. Salt accumulation in front of blade is not taking place. The drawbacks of the above noted "Mechanical salt harvester for Indian Salt Works and Mechanical Salt Harvester" are given below: The device possessed all the drawbacks of the device shown in Fig.2. Here the said washing function is just a brine separation effect due to transfer of wet salt in conveyors. In Fig.4 of the drawings is shown a schematic diagram of a "Mechanical Salt Transporter". A report by R.P.Dhiman & A.S.Kane of Central Salt & Marine Chemicals Research Institute, Bhavnagar constituent laboratory of Council of Scientific & Industrial Research and a Mechanical Salt Transporter by R.P.Dhiman & B.S.Purabia, published in Salt Research & Industry, Vol.7, No.2&3, Apr-July, 1970, p.68. The design of transporter (21) is based on the principle of the trajectory of a particle, projected in an oblique direction of the horizontal which is a parabolic curve (22). The transporter consists essentially of a belt conveyor (23) fitted with small strips to prevent slipping back of the salt, moving at about 25 mtrs. per second linear speed in a frame which can be used in full length of about 1.5 to 3 mtrs. by removing the head end portion. The conveyor belt is also in two parts (24) to suit this system. The conveyor belt and frame are mounted on a cubical structural frame containing a 6 kw air cooled engine (25) to provide power to the belt conveyor through a gear box. The whole mechanism described above is fitted in such a way on a flat trailer with cylindrical wheels as to turn through 180° to a point to the back or either sides of the salt harvester. During trial it has been found that at an angle of 45° the salt was thrown to a distance of about 13 meters and at 30° to a distance of 10 meters. The transporter weighs about 200 kg. giving a bearing pressure less than 0.2 kg. per sq.cm. (26). The experimental performance is 20% of the theoretical values using projectile equations. The reduction in distance is on account of the air resistance acting against the throw of salt particles. The drawbacks of the above noted "Mechanical Salt Transporter" are given below. The salt transportation problem explained earlier was attempted to solve by flying/throwing principle. With this, salt found spreaded form from one place to another instead of accumulated collection. Moreover it is an energy intensive method for a cheap product like raw salt. linear speed in a frame which can be used in full length of about 1.5 to 3 mtrs. by removing the head end portion. The conveyor belt is also in two parts (24) to suit this system. The conveyor belt and frame are mounted on a cubical structural frame containing a 6 kw air cooled engine (25) to provide power to the belt conveyor through a gear box. The whole mechanism described above is fitted in such a way on a flat trailer with cylindrical wheels as to turn through 180° to a point to the back or either sides of the salt harvester. During trial it has been found that at an angle of 45° the salt was thrown to a distance of about 13 meters and at 30° to a distance of 10 meters. The transporter weighs about 200 kg. giving a bearing pressure less than 0.2 kg. per sq.cm. (26). The experimental performance is 20% of the theoretical values using projectile equations. The reduction in distance is on account of the air resistance acting against the throw of salt particles. The drawbacks of the above noted "Mechanical Salt Transporter" are given below. The salt transportation problem explained earlier was attempted to solve by flying/throwing principle. With this, salt found spreaded form from one place to another instead of accumulated collection. Moreover it is an energy intensive method for a cheap product like raw salt. In Fig.5 of the drawings is shown a schematic diagram of a "Tractor driven mechanical salt harvester TD-2". A report by R.P.Dhiman and Dr.A.S.Kane and "Tractor driven mechanical salt harvester" by Dr.A.S.Kane, published in Salt Research & Industry, Vol4, No.l, Jan. 1967, p.22. This is a patented device No.l 11847 dt. 7-Aug-1967 by Dr.A.S.Kane and H.N.Patel both of Central Salt & Marine Chemicals Research Institute, Bhavnagar, constituent laboratory of Council of Scientific & Industrial Research and Indians. This harvester device is operated by a tractor. It consists two floating buckets holding belt conveyors (26) side by side. Top ends of the conveyors are away from the tractor, its lower ends carry carbon steel scraping blades (27) each 60 cm wide and spaced apart by a span of 60 cm, leaving blank belt of salt layer in between the two cut strips. Both the blades are provided with the rotors (30) to pass the scraped salt into the buckets of the belt conveyors. The cutting depth of salt layer is controlled by the top links and other screwed lever adjustments. The harvester is liftable by the hydraulic systems of the tractor. The harvesting capacity is 20 ton/hr. (28). The trials were conducted at M/s. United Salt Works, Kandla and at Experimental Salt Farm, Central Salt & Marine Chemicals Research Institute (CSMCRI), Bhavnagar. An unraked salt layer of 5 cm. thickness has bearing strength of 1 kg./sq.cm. This is based on the tractor tyre filled with that pressure and doesn't sink into the crystalliser bed. The use of the harvester is advisable for the salt farms producing min. 25000 tons of salt per year. The total weight of the harvester is 460 kg. There are two supporting drums (29) at the rear end of the harvester. A trailer (36) of 2 tons capacity was attached behind the harvester. Here power with its transmission worked well. The scraped salt layer (35) was approximately 2.5 cm thick. The drawbacks of the above noted "Tractor driven mechanical salt harvester TD-2 and Tractor driven mechanical salt harvester " are given below. The hauling problem of 10 trailers per hour was required to be managed. The traffic frequency and the salt bed conditions were not made for each other. This created limitation in its extensive use till today. It posed a question what to do after lifting the scraped salt, in a salt bed that itself is not strong enough to withstand repetitive pass. In Fig.6 of the drawings is shown a schematic diagram of a "Use of mechanical salt harvester in partial harvesting operation of scraping and breaking of hard layer of salt" by B.S.Purabia, Dr. A.S.Kane and Dr.M.HJadhav, published in Salt Research & Industry, Vol.7, No.2 & 3, Apr-July, 1970, p.66,67. As a matter of conducting trials with limited actions of harvester, both the belt conveyors (26) of Fig.5 and their lower covers (27) and rotors (30) as well as trailer (36) were diassembled. Hard unraked salt layer of 10 cm. thickness (37) was then scraped in the crystallisers of M/s. Saurashtra Salt Mfg. Co. at Porbandar, Gujarat for 17 whole days. The bearing strength of the crystalliser bed was 1 to 1.5 kg. per sq.cm. The scraping capacity of 35 HP tractor was measured as 80 tons of salt per hour (33) by consuming 1.5 litre diesel fuel. The trials for three days were also conducted at M/s. Saurashtra Chemicals using complete assembled harvester. The need was felt to develop the suitable transportation device. The drawbacks of the above noted "Use of mechanical salt harvester in partial harvesting operation of scraping and breaking of hard layer of salt" are given below. The limited scraping portion of the device shown in Fig.5 ((27) was tested by using both the blades. It produced loose salt with big salt lumps without shifting its location. These lumps are required to be reduced in size before washing or during stacking as they fall back from the steep belt conveyor and harm the workers. Not only that manual collection of it from the crystalliser itself is an ardous task left behind. In Fig.7 of the drawings is shown a schematic diagram of a "Cover elevator salt harvester" by B.S. Purbia, published in Salt Research & Industry, Vol.4, No.2, Apr., 1967,p.55. This harvester was a tractor operated portable device. A scraping blade (38) was 2 mtr. wide. The raked salt is scraped and lifted by the buckets carried by the 2 mtr. wide belt conveyor (39). It discharges towards the tractor side on a horizontal belt conveyor (40) extended to its one side to facilitate it for dumping into a trailer running parallel to the harvester. The loaded trailer travels on unscraped salt bed surface. The weight of the device is toward the tractor wheels, and favourable rotation of conveyor does not allow salt to accumulate in front of the blade. Long scraping blade could not scrap the hard salt layer successfully and uniformly. Trailer traffic frequency still remains a problem. In Fig.8 of the drawings is shown a schematic diagram of a "Mechanical harvesting of salt" by R.A.Parikh of Tata Chemicals Limited, Mithapur, Gujarat, India, published in Salt Research and Industry, Vol. 1, No.2, July, 1964, p. 19. The pans of 5 acres (330 m x 53 m) is recommended as a fixed size for harvester to work as shown in top plan (50). Nearly 7.5 cm. unraked and drained salt layer is allowed to crystallize. It is loosened first by the tractor operated rotating cutter (41). The function of this harvester is to scrap/collect (42) the loosened salt, lift it (43) and convey (44) upto the trailer (45) standing outside the pan. The harvester weighed about 10 tons and supported by 7 crawler wheels (46). A 26.5 mtr. long structure (47) of 1 m x 1.3 m. cross section area carries belt conveyor. A scraping trolley (48) travels to and fro on the rail mounted on long structure and the support wheels. The belt conveyor end near the bund dumps salt into a drag elevator (49) that lifts and further dumps into a trailer. After harvesting half the pan lengthwise other half of the pan is harvested by turning 26.5 mtr. long structure at 180° inside the pan. After harvesting the entire pan it turns 90° and crosses the bund of 0.3 mtr. hight with sufficient slope. A need to increase the harvesting capacity was felt at the time of approaching monsoon season. The drawbacks of the above noted "Mechanical harvesting of salt" are given below. Indian salt works have the crystallizer pans of different sizes, whereas the developed device has applicability only with the specific size of the pan. Moreover, the structure of this harvester was heavy and long one to transfer in the pans, or outside on platform or to shelter it in the salt works. Its maintenance was costly, time consuming and difficult. In Fig.9 of the drawings is shown a schematic diagram of a "Mechanisation in salt production - with an observation of an existing salt harvester in the year 1997-1998" by K.M.Majeetia of Central Salt & Marine Chemicals Research Institute, Bhavnagar, constituent laoratory of Council of Scientific & Industrial Research, published in Salt Research & Industry, Vol.10, No.2, Sept., 1974, p.29. The collected information is from the report as well as from the observation of the existing salt harvester at Central Salt & Marine Chemicals Research Institute. It is an articulated assembly of three chain conveyors (51,52,53) and inclined blade (54) with seven tines (55) mounted on a frame supported on two pneumatic rear wheels (56) 0.75 m diameter and a peg (57) as central support in the front. The whole frame is drawable from the middle front point by a single rear pulling pivot of the tractor. The power is taken from the power take off shaft of the tractor. The steel blade 1.5 m wide scarps the salt layer followed by the scarifying penetration of 7 tines. The blades scrap raked/unraked salt layer and push it into the drag conveyor (51) that discharges salt on a horizontal 0.3 m wide transversely placed chain mounted staggered belt conveyor (52) at a height of 0.75 m above the bed. The third is also 0.3 m wide inclined bucket mounted belt elevator (53) that dumps salt into the trailer (58) through a chute. The capacity of the harvester is 50 tons/hr. The weight of this harvesting device without engine mounted on it is about 1 ton. It has also been calculated in the year 1974 that the expenditure by manual harvesting of Rs.2 per ton will come down to Rs. 1.3 per ton of salt by employing this device. The drawbacks of the above noted "Mechanisation in the salt production -with an observation of an existing salt harvester in the year 1997-1998" are given below. The device is not manoeuverable type as the harvester is drawable only. The assembly of 18 sprockets and 9 link chains demand frequent maintenance. Salt transportation problem is similar to the one explained earlier considering the medium size salt works. In Fig. 10 of the drawings is shown a schematic diagram of "An evolution of harvesting methods and mechanisation in small salt works " by M. Rocha, E. Regato and F. Almeida, Portugal, Pb.Fifth International Symposium on Salt Vol.2, 1966, Northern Ohio Geological Society, p.367-370. The diagram is drawn from the description given in the original text. Harvesting consists of removing the crystals from the location of their precipitation. The salters soon verified that this operation was one of the most significant in the productive process, later on, they would learn it was the hardest and most expensive one. Ultimately the industrial revolution reached the salt ponds by the introduction of mechanical procedures, able to perform the operations with a minimum of human effort. Harvesting still holds an important position because a great percentage of the expenses are incurred during its completion. Stages of harvesting: Residual brines are drained (61). The salt layer is extracted, broken up and separated from the bottom (62) and elevated (63). The salt is then first removed (lateralized) (64), Loaded on containers or vehicles (65), Moved again and transported to Washing, from there moved to (67) again and finally piled (68). Explaining further, salt layer is removed with the width of the attacking blade. The dragging harvesting methods require a fractioning using a hollow or an adapted rotary cultivator (62) with special teeth. After this salt is carried to the border of the pond, by dragging or by utilisation of containers, vehicles or belt conveyors, (containers are baskets, hampers, basins, buckets etc. and vehicles are trailers, trucks, lorries, dumpers etc.) when containers or vehicles are used the salt is carried to the pile or washing machine. In other cases, the salt is dragged or raked to the borders of the pans, accumulated there and stays there some time. The dragging methods are solutions specially adaptable to small salt works and to those where the bottoms have low traffic possibilities. They consist in lateralizing the salt, employing a drag set, pulled by a winch (66) on the pond border (64). The drag set may be provided with a motor/tractor, where rear movement is manual. Transport vehicles are loaded with a retroescavator and pulled on trailers attached to farming tractors. The dragging plate is 2.3 m x 0.5 m (69). Beside the system which uses a retroescavator bucket, a helicoidal screw and conveyor belt are also used. To load vehicles with salt heaped on borders, the helicoidal screw and small conveyer belts are employed. These are fed when necessary, with shovel operators. The aim of the technological methods suitable to small salt works still has to be considered in an experimental phase. New adaptable solutions are foreseen. The drawbacks of the above noted "Evolution of harvesting methods and mechanisation in small salt works " are given below. Salt layer is loosened first by a harrow or cultivator then is dragged by a plate 2.3m x 0.5m and wire rope using motorised winch, placed on platform. Trailers are loaded by using screw or belt conveyor. Here collection (lateralization) is not a continuous one, it is reciprocating type movement that has its own mechanical disadvantages. The method compared to other machines engages more number of workers. In Fig. 11 of the drawings is shown a shematic diagram of "A General practice of manual salt harvesting" which is based on the experience in Experimental Salt Farm of Central Salt & Marine Chemicals Research Institute (CSMCRI), Bhavnagar, constituent laboratory of Council of Scientific & Industrial Research (CSIR). The crystallizer sizes are 122 m x 38 m (400 ft x 125 ft). The 25 mm (1 inch) thick raked salt layer of a pan is scraped by 33 workers in 5 hours forming 33 heaps (71). All the heaps are allowed to drain and the collection becomes 100 tonnes. They are transferred manually and dumped into the trailers standing outside the pan by carrying it as head load by walking on hard angular salt crystals. Some of them suffer from boils and other skin diseases resulting from constant irritation due to prolonged contact their feet have with salt and brine in pans. The wooden plank (72) is placed on the bund to cross it with head load. The trailers have four tons haul capacity (73) In nutshell the workers attend the following tasks in the salt farm. Preparation of pan beds (77) formation and maintenance of bunds and channels (76) the regular raking work of crystallised salt (78) scraping of salt and formation of heaps (71) loading the trailers, closing and opening the feed mouths of brine flow (75) feeding the conveyor hoppers (74) digging the stacks and/or loading the trucks (79), etc. Generally the following mechanical equipments are used in salt works; Rear wheel drive diesel tractors, dumpers/loaders, trailers, belt conveyors, slurry pumps, diesel engines, and trucks. The following manual tools are also used: Soil stabilizing rolls, pickaxes, shovels, baskets, rakers, etc. The production of salt is increasing gradually in India. The available salt farm condition and the mechanical designs developed abroad could not match each other for years. As a result there prevails a feeling of high time to develop an adaptable mechanical design to work in the widely scattered medium size salt farms of India. Providing potable water from far end to the workers is also becoming a difficult problem. The drawbacks of the above noted "A General practice of manual salt harvesting" are given below: Any hard work done manually will not have productivity gain. Large gang of workers impose management problems. Parallel season of agricultural work in India creates poor availability of trained workers willing to do the cheap work under extreme working conditions. Global price competition does not favour the method. In Fig. 12 of the drawing is shown a schematic diagram of "The salt extraction equipment mounted on MTZ tractor". Book: Technologia De La Sal Marina by Abilio Garcia Merlot (The Marine Salt Technology, Spanish), p.219, Pb.Ministerio De Mineria Y Geologia La, Habana, 1977. It is a tractor mounted design of salt harvester moving reverse (81). A screw with blade (82) passes accumulated salt into a bucket mounted belt conveyor (83) that ultimately dumps into a horizontal conveyor (84) which is collected by a forward driving trailered tractor (85). The drawbacks of the above noted "The salt extraction equipment mounted on MTZ tractor" are given below. The device is similar to the one developed earlier in India (see Fig.7). It is heavy, difficult to maintain and requires more than 75 mm thick salt layer to operate. In Fig. 13 of the drawing is shown a schematic diagram of "The agricultural equipment adapted for chopping of salt layer", pp.220 of the same above referred Spanish book.. It is a ploughing teeth implement attached behind the tractor on a beam in helical form that works in the salt layer for loosening purpose when tractor moves in the reverse direction. The drawbacks of the above noted "The agricultural equipment adapted for chopping of salt layer" are given below. It is a tractor mounted salt loosener and not a harvester as it does not remove the crystals from the location of their precipitation. In Fig. 14 of the drawing is shown a schematic diagram of "The combined self driven salt harvester", p.222 of the same above referred Spanish book. A crawler wheel type tractor is developed in a way to perform as a harvester. It has a screw (86) and a guide roll (87) in front to pass salt to both sides of drag conveyors (88) that dumps into a horizontal belt conveyor (89) that again dumps into a tractor attached trailer (90) moving in forward direction. Here two types of design capacities are described: (Table Removed) The drawbacks of the above noted "The combined self driven salt harvester" are given below. It is a heavy and high capacity harvester for large size salt works, and less likely to find application in India for want of crystallizer conditions. As the proposed transportation style will damage the bed or will need to sacrifice a thick left out salt crop, by changing the level of the salt farm layout. In Fig. 15 of the drawings is shown a schematic diagram of "Harvest of solar salt at Salin-de-Giraud, France" by P.de Flers, B. De Saboulin & J. Clain, Compagnie des Salins du Midi et des Salines de Test, 51 Rue d'Anjou, 75008, Paris, France. Book: Salt Symposium, Part 4th, (1966), Vol.2, p.408. The solar salt works covers an area of 11000 hectares (27170 acres as 1 hactare = 2.47 acres). The average salt production amounts to 900000 tonnes. The harvesting rate is 30000 tons per day. This goes for about 30-35 days. The blade of 3.8 m width (91) advances at a speed of 30 to 60 m/min. by cutting 90 mm thick salt layer. The salt production rate is 1500-1600 tonnes/hectare/hr. minimum. The cut layer falls on internal face of the conveyor (92) which in turn deposits the salt on a second conveyor (93) that removes the salt outside. The harvesting device is fitted to a conventional caterpillar tractor (95) the width of which is such that the tread pressure of the equipment is approx. 0.5 kg. per sq.cm. A harvesting site is composed of two salt harvesters, several aligned horizontal self propelled belt conveyors having 50 m unit length (94) and a belt elevator for the stock piling (96). Only 12 men are required for operation of all the equipments. The drawbacks of the above noted "Harvest of solar salt at Salin-de-Giraud, France " are given below. The device will not be suitable for medium size salt works of India due to the problems of its heavy capacity. There are few other large capacity harvesters working in the salt works world over. Since here we are more concerned with the smaller capacity devices for medium size salt works, their descriptions are not included. Each harvester requires to sacrifice the initial salt crop layer temporarily or permanently. Heavy harvesters need heavy amount of left out salt crop. The temporarily left out crop that comes to about 20 to 30 per cent of the total considering the present design may be collected manually, at the end of the season. This stands as substitute to a brick lined and stablised crystallizer bed, for attaining the required bearing strength, to run the device. The presentation of detail description of all the prior arts is as follows. All the figures drawn are schematic line drawings just to explain the working principles of the main components without showing structural or assembly details to any scale. The numbers/ alphabets shown in brackets are referred from the respective figures. The main object of the present invention is to provide a device useful for harvesting/ridging of salt/soil which obviates the drawbacks as detailed above. Another object of the present invention is to provide a device to form soil ridges to develop salt farms, where channels, bunds and pan beds are formed with the help of the suitable salt/soil ridger. Still another object of the present invention is to provide a device capable of extending the scraping and conveying function for a long horizontal distance, using a mobile power source from outside the pan, which helps in conveying predominant ridger device to do the job of transporter. Yet another object of the invention is to dump the ridged material into an integrated container placed above the mobile power source (tractor etc.), having hydraulic hauling advantages used intermittently,and thereby performing scraping, conveying, lifting and hauling the ridge of salt/soil. In Figure 16 to 18 of the drawings accompanying this specifications the schematic diagrams of the parts and assembled device of the present invention are shown. Fig. 16 of the drawing shows helical screw, a part of a screw conveyor, of the device having one or more helixes. Fig. 16(i) shows the elevation and Fig.l6(ii) shows the end view. Fig. 17 of the drawing shows the cover/trough of the helical screw, a part of a scew conveyor, of the device. Fig.l7(i) shows the elevation. Fig.l7(ii) shows the end view and Fig,17(iii) shows the top view. Fig. 18 of the drawing shows the assembled view of the present invention. Fig. 18(i) shows the end view. Fig. 18(ii) shows the elevation. Accordingly the present invention provides A device useful for harvesting/ridging of salt/soil, which comprises one or more helical screw conveyors (a) mounted on a horizontal shaft (b.c), the helical screw conveyor being provided at one end with at least half turn of reverse helical screw (e) the said helical screw conveyor periphery being also provided with teeth (d) capable of cutting salt/soil layer, the said helical screw conveyor mounted on horizontal shaft being encases in an open bottom trough/cover (f) having ground support, the cover being provided with front inlets (h) and a rear outlet (g) at the reverse helical scew (e) end, the said cover (f) being provided at lower following edge with a scraping blade (i) and a baffle (j) at the front, the said horizontal shaft (b) ends (c) being provided with known means (k,l,m) for coupling with a known prime mover. Scraping depth controlling pads (n) is provided to support the trough. In an embodiment of the present invention the helical sqew conveyor used may be such as single or multistart helix. In an another embodiment of the present invention the known means used for coupling the shaft ends to a prime mover may be such as chain, sprockets, pulleys, gears, couplings and clutches. In yet another embodiment of the present invention the prime mover used may be such as tractor, crawler, loader and dumper. In figures 19 to 23 of the drawings the use of the device of the present invention is shown. Fig. 19 shows the side view of the device of the present invention attached with the tractor. Fig.20 shows the top view of the device of the present invention attached with the tractor. Fig.21 shows the path of the movement of the device of the present invention along with the tractor from top view. Fig.22 shows the cross sectional view of the crystalliser. Fig.23 shows the path of the movement of the device of the present invention along with the tractor from top view. An embodiment of the use of the device of the present invention is detailed below: The tractor operated salt farm ridger (harvester) which uses a mobile power source like agricultural farm tractor (101), loader, etc. to which device like the ridger (102) can be attached in a way to make it rotating at a certain place, level, route, speed and arrangement with respect to the level of mobile power unit or to the level of the salt/soil bed (103) to work upon, as to scrap or loosen the required depth of the raked/unraked salt/soil bed (103) by adjusting the dummy support wheels and or sliding foot plate, (116) hydraulic control, top link etc. and convey the same scraped salt/soil material simultaneously and or the previously scraped and accumulated material (104) together to either side (105) of the entire ridger length or may also be lifted above the salt/soil bed as second alternative to work as loader or transporter, with the help of no workers or few workers, as per the expected duties of the ridger, that always travels transversely i.e. in the normal direction to its length, maintaining contact with the salt/soil bed while it performs, that may or may not be liftable by itself or by means of hydraulic/pneumatic devices. The implement moves with mobile power unit in straight/spiral suitably to form salt/soil ridges (107) and to transfer the salt/soil with/without hauling facilities. The pneumatic tyre wheels of the tractor/mobile power unit may be twin or tripple with minimum tire tread lug height to suit the bed strength. The ridger is an attachable modified design of a screw conveyor carrying two components mainly as conveyor screw (108) and its trough (109) assembled to perform as ridger, which is also an activity of salt harvester by definition. The said screw has suitable diameter & length having selective materials to resist corrosive and abrasive working/ conditions. The screw has right or left hand multistart helix of suitable angle witH plain and close blade (flight) configuration. The cutting sharp teeth (110) are place all around the helix blade edges. The screw shaft may be solid, hollow or flexible fully or partly in a single or several aligned unit length each of appx. 2 to 3 m size The trough may be cylindrical/polygonal (109) made up of perforated/unperforatedl sheet, withjjuitable mouths to perform in dry or wet conditions. Each unit length of! the screw has always a lengthwise open slit (111) at the bottom to establish contact with the bed and scraping blade (113) fitted to it. There is also a provision for brine controlling baffles (112). It also carries ultimate inlet (114) and outlet (115) mouths. The transverse trough is rigid enough to withstand against draw-bar pull during straight and turning movements of the tractor. The principal use and innovative aspect of the device of the present invention is to form ridges of salt/soil in the salt farm by a combined action of scraping and dragging (lateralizing) of the bed and to form ridges (107) at an approachable distance from the bund. Description of the device of the present invention is detailed below: The device is mounted on three point linkage of a tractor and is hydraulic controlled. The liftable implement consists a single unit of screw conveyor (ridger) attached transverse to the direction of tractor travel of suitable length, diameter and shape to perform the duties of scraping and conveying. The screw has multi-start flights of suitable angle. It carries scraping teeth all around to the edges of the flights. Another straight blades at the bottom of the trough are for scraping and or accumulating salt/soil. There is also a baffle attached to the trough to facilitate the working with the wet salt/soil. There are outlet and inlet mouths at the ends of the trough one opposite the other, the openings are of heap shape suitable for forming the ridge work. The screw and the trough are assembled by means of two end bearings. The screw conveyor is rotated by the tractor power take off shaft at a required speed by means of using sprockets, chains, gear box, universal joints and line shaft. They are all supported by the trough and the tractor. The cutters fitted on the screw conveyor are pieces of hard steel straight stripes, radially erect at equi-distance, keeping flat plane perpendicular to the axes of screw shaft, and fixed on the non-pushing face of the screw flights. Their cutting edge ends/teeth are sharpened. The trough has a lengthwise open slit to establish contact of the screw with the bed to be scraped. The scraping depth is adjusted in proportion to the power of the tractor in use. The two adjustable flat base plate (116) are provided on the outer ends of the trough to control and maintain the depth of scraping. The material is selected to resist corrosive and abrasive working conditions. Lubrication to working parts is provided. The operation of the device of the present invention is detailed below: The place shown as point (106) is from where the ridger starts functioning in the crystallizer pan. The depth of cut is adjusted as explained earlier. A /small ridge is formed in the beginning. In the diagram the spirally travelling line indicates the path of the ridge that simultaneously being wiped out from inner side and forms the higher size ridge ahead as seen at the point (104,105) on outer sides. After reaching the capacity of the ridger to its maximum at point (117) or around the ridger is adjusted to stop cutting and does the job of conveying only and it continues travelling spirally till the formed ridge (117) is dragged close to the bund, by moving and touching just above the bed surface upto (107,118). The ridger starts scraping work again from the point say at (117), and continues till it reaches to its maximum capacity. Repeatatively thus the number of large size ridges are formed beside the bund (119). The number of ridges depends on the capacity of the ridger i.e. the max. amount per unit length, the depth of cut, the size of the pan and the wetness of the salt/soil. The above explained length of scraping path may be called a pass. The passes may be arranged as one or more in a pan by adjusting the depth of cut till to the place closer to the bund. Fig.22 & 23 shows alternative methods of travelling the device inside the crystallizer. In case of spiral path the device starts from the middle, whereas for zig¬zag path it begins from one corner of the crystallizer. Spiral path is easy and more preferable. Fig.21, 22 & 23 explains the details of the field experiment of the present invention for the purpose of forming ridges of salt. The following examples are given by way of illustration of the present invention and should not be construed to limit the scope of the present invention. Example-1 The device of the present invention was mounted on the three point linkage of the 35 HP tractor. The length of the screw conveyor is wider than the width of the tractor. Power take off shaft end is connected to the ridger driving shaft by means of universal joints. The screw rotates at a speed in proportion to the tractor travel. The scrapable depth of layer is controlled by operating hydraulic system of the tractor, adjusting the sliding foot plates and the top link length. The ridge forming capacity is measured to 30 tons/hour. The measurement relates to the largest size of the ridge formed during the experiment. Examplc-2 The device of the present invention was tried in wet salt conditions, with small quantity of brine available in the crystallizer. The salt scraped and moved sideways got agitated with adhering brine and got partially washed to remove chemical impurities, magnesium in particular. The brine control and salt washing performance is yet to be confirmed in full chemical analysis. But a visual evidence of improved whiteness was noted. The functional test was found quite satisfactory. The capacity measurement was not carried out on account of wet conditions and rainy season during the trial. Example-3 The device of the present invention was mounted on 45 HP diesel tractor and the ridge forming capacity was measured to 40 tons/hr. In all these experiments the layer of salt is about 50 mm thick in the pan and the ridger scrapped about 13-15 mm depth of the unraked salt layer in the beginning. Example-4 The device of the present invention was tried for forming soil ridges. It worked successfully and found no challenge in its performance. The capacity measurement is omitted for the time being to concentrate more on the salt scraping performance. But in no case found visually less than the capacity of salt. The main advantages of the present invention are as follows: 1. It is light weight, simple, easy to operate, maintain, manoeuverable, portable and cheap for the cheap material like salt/soil with the mechanical facilities available at the remote places of medium sized salt works. 2. The maximum left out salt crop is not more than 20% of the total production in a season. 3. The function of the ridger is such that the traffic across the pan is most limited, say as only two times during harvesting or formation of ridges of one crop of a pan. 4. A tractor driver with an attendant is sufficient to work with the device, and to bring the salt near the bund. 5. The ridger device contributes to the size reduction of salt/soil by scarifying the layer inspite of working with the raked/unraked bed. This is favourable for washing and stacking of salt. 6. The ridge formation work of salt in presence of washing brine contributes to the upgradation of salt automatically, since the screw has inherent functional advantage of intensive solid liquid mixing and separating to leave behind the physical and chemical impurities of salt of the scraped bed. The residual draining also takes place after forming ridges. The washing action is performed almost without any further facilities and investments. 7. The salt production quantity is increased as a result of clearing the pan faster and to start with the earliest evaporation/concentration work. 8. The ridge formation of soil is also a hard work like salt if attended manually. This implement performs excavating and transferring farm soils to develop the pans and to form the bunds, channels etc. This is applicable to both salty as well as fertile type of soil. 9. The product salt price comes down, on account of the efficient productivity offered by the device. 10.The salt bed left undisturbed bottom due to this bearable, carefully planned vehicular traffic inside the pan, by the device. 11 .A portable ramp like facility is sufficient for the entrance of the implement in the pan. 12.An additional vertical conveyor and a container contributes to the material hauling facilities by dumping the ridge of salt/soil into self mounted integral container, since the material accumulation begins from the lowest level of the implement. This does not require any parallel source of power (say for example a tractor) carrying container and running beside the ridger, as is the case with most of the harvesters. The container is emptied hydraulically intermittently. 13.The short screw conveyor (ridger) is a scraping predominant device. Similarly long assembled screw conveyors (ridger) provide a conveying predominant device. The second device is suitable where scraping power requirement is negligible, e.g. Baragara (large loose crystalline) salt/soil. 14.The device of the present invention provides an answer to the problem of salt harvesting by mechanical means for the medium size salt works of India and abroad which was carried out uptill now manually and uneconomically. We Claim: 1. A device useful for harvesting/ridging of salt/soil, which comprises one or more helical screw conveyors (a) mounted on a horizontal shaft (b.c), the helical screw conveyor being provided at one end with at least half turn of reverse helical screw (e) the said helical screw conveyor periphery being also provided with teeth (d) capable of cutting salt/soil layer, the said helical screw conveyor mounted on horizontal shaft being encases in an open bottom trough/cover (f) having ground support, the cover being provided with front inlets (h) and a rear outlet (g) at the reverse helical screw (e) end, the said cover (f) being provided at lower following edge with a scraping blade (i) and a baffle (j) at the front, the said horizontal shaft (b) ends (c) being provided with known means (k,l,m) for coupling with a known prime mover. 2. A device as claimed in claim 1, wherein the helical screw conveyor used is a single or multistart helix. 3. A device as claimed in claim 1 and 2, wherein the known means used for coupling the shaft ends to a prime mover is selected form chains, sprockets, pulleys, gears, clutches and universal joints. 4. A device as claimed in claims 1 to 3, wherein the prime mover used is selected from group consisting of tractor, crawler, loader and dumper. 5. A deice useful for harvesting/riding of salt/soil substantially as herein described with reference to the examples and drawings accompanying this specification.

Full Text

The present invention relates to a device useful for harvesting/ridging of salt/soil.
The device of the present invention may be used in conjunction with a prime-mover such as a tractor (the first selected source of mobile power designed to work in agricultural farm, and utilised here for salt/soil layer fractioning, cutting, scraping, loosening, scarifying, chopping, raking and ridge formation along with material haulage) for salt farming work.
The main usage of the device of the present invention is in the salt farm to scrap the salt layer of uniform thickness, accumulate and convey or transfer the same simultaneously upto the bund of the pan in the form of salt ridges (the linear formation of heaps along with the path of the tractor travelling). Similarly soil ridges are also formed by scraping salt farm soil to the required pan dimensions of its length and breadth. Basically harvesting of salt consists of removing the crystals from the localtion of precipitation. Harvesting is a major factor in the cost of salt production. The handling problem represents an important factor in the cost of salt.
Salt is always found in spreaded form on flat land, having poor traffic possibilities called the crystallizer pan bed, particularly in all the middle size salt works of India, where the evaporation of salty water is taking place through the
utilisation of cheapest natural source of solar and wind energy. Till now crystallised salt is collected manually almost everywhere in India and elsewhere in medium size salt works, producing minimum ten thousand tons of salt per year.
The use of the device of the present invention is possible only when the bearing strength of the bed is capable enough to permit the operation of the ridger without damaging the bed i.e. pan bottom or spoiling the quality of salt, by an addition of clay/mud in the product. Here the tread pressure of the wheels due to the weight of the tractor mounted ridger is considered balancing against the effective strength of the salt layer.
The conventional heavy mechanical salt harvesters are applicable to large salt works where scraping, lifting and dumping works are performed together in a big
way.
The technical field of the present work is classified as: Salt Works Engineering, Material Handling, Production Engineering, Mechanical Engineering & Agricultural Engineering.
Presently there are several equipments/devices which are known for salt harvesting. The working actions of all the known salt harvesters can be divided into two types. The first and main action is to scrap the raked or unraked layer of crystallised salt. The second and subsidiary action is to elevate, dump and transport the same to a long distance or simply transfer the same salt by dragging it to a limited internal distance of pan without lifting it all through. Mostly prior salt harvesters follow scraping, lifting, plus dumping and transferring, whereas the design of the present invention advocates for scraping and dragging the same salt without lifting it all through.
In Fig.l of the drawings is shown a schematic diagram of a "Semi-mechanised salt harvester" by R.P.Dhiman, R.V.Bhatt, D.S.Datar & R.L.Dutta of Central Salt and Marine Chemicals Research Institute, Bhavnagar, constituent laboratory of Council of Scientific and Industrial Research, published in Salt Research & Industry, Vol.2, No.3, July 1965, p. 111.
The maximum working capacity (1) of the design is 10 tons per hour. The weight of the harvester is 230 kg. It exerts pressure on bed (2) of about 0.35 kg per sq.cm. An inclined 0.66 m [2 ft] wide blade (3) carrying conveyor (4) is pulled forward manually (5) to scrap the raked salt layer. The conveyor dumps the salt into trailer (6) or into the van moving behind the harvester. The drawbacks of the above noted "Semi-mechanised salt harvester" are given below:
Two workers were pulling the harvester with their hands held on the backsides. The pull was found limited to run the harvester continuously for one hour.
In Fig.2 of the drawings is shown a schematic diagram of a "Mechanical salt harvester for Indian Salt Works ". A report by R.P.Dhiman and A.S.Kane of Central Salt & Marine Chemicals Research Institute, Bhavnagar, constituent laboratory of Council of Scientific & Industrial Research.
The design consists 60 cm. wide steel blade (7) which cuts a layer of salt while moving forward which is then lifted up by a belt conveyor (8) that dumps into a trailer through a chute (9). The harvester is powered with a 6 kw air cooled engine (10). It has a salt harvesting capacity of 5 tons per hour (11). It is suitable for small salt works of upto 10,000 tons per year production capacity. The attached trailer (12) has 1 ton hauling capacity. Salt accumulation was taking place in front of the blade. The drawbacks of the above noted "Mechanical Salt harvester for Indian Salt Works " are given below:
The hauling problem of 5 trailers per hour was required to be managed. The traffic frequency and the salt bed conditions were not made for each other. This self
powered design had inherent mechanical power transmission problems. It could not harvest one pan worth salt.
In Fig.3 of the drawings is shown a schematic diagram of a "Mechanical salt harvester for Indian Salt Works". A report by R.P.Dhiman and Dr.A.S.Kane of Central Salt & Marine Chemicals Research Institute, Bhavnagar, constituent laboratory of Council of Scientific & Industrial Research and Mechanical Salt Harvester by R.P.Dhiman, published in Salt Research & Industry, Vol.5, NO.3&4, July-Oct, 1968,p.81.
It is a mechanical salt harvester SD-2A, a compact apparatus for cutting, lifting and washing of salt from the crystalliser. The harvester has 10-15 tons per hour capacity (13). It consists essentially of two conveyors, the lower one (14) which is carried in a frame, which can be raised when not required for harvesting or lowered for harvesting of salt as required. At the lower end of the frame is a special 60 cm. wide steel blade (15) which can be lowered down into the salt by means of screwed lever mechanism when the harvester moves forward, thus cutting an accurately controlled layer of salt which is lifted up into an accumulator (16) where the salt gets drained, from which the upper conveyor (17) lifts it to a height of about two meters above salt bed and dumps salt into a trailer (19) attached behind the
harvester through a chute (18). The harvester is powered by a 11 kw self start engine (20) which drives the harvester as well as the conveyors and trailer at different selective speeds. Salt accumulation in front of blade is not taking place.
The drawbacks of the above noted "Mechanical salt harvester for Indian Salt Works and Mechanical Salt Harvester" are given below:
The device possessed all the drawbacks of the device shown in Fig.2. Here the said washing function is just a brine separation effect due to transfer of wet salt in conveyors.
In Fig.4 of the drawings is shown a schematic diagram of a "Mechanical Salt Transporter". A report by R.P.Dhiman & A.S.Kane of Central Salt & Marine Chemicals Research Institute, Bhavnagar constituent laboratory of Council of Scientific & Industrial Research and a Mechanical Salt Transporter by R.P.Dhiman & B.S.Purabia, published in Salt Research & Industry, Vol.7, No.2&3, Apr-July, 1970, p.68.
The design of transporter (21) is based on the principle of the trajectory of a particle, projected in an oblique direction of the horizontal which is a parabolic curve (22). The transporter consists essentially of a belt conveyor (23) fitted with small strips to prevent slipping back of the salt, moving at about 25 mtrs. per second
linear speed in a frame which can be used in full length of about 1.5 to 3 mtrs. by removing the head end portion. The conveyor belt is also in two parts (24) to suit this system. The conveyor belt and frame are mounted on a cubical structural frame containing a 6 kw air cooled engine (25) to provide power to the belt conveyor through a gear box. The whole mechanism described above is fitted in such a way on a flat trailer with cylindrical wheels as to turn through 180° to a point to the back or either sides of the salt harvester. During trial it has been found that at an angle of 45° the salt was thrown to a distance of about 13 meters and at 30° to a distance of 10 meters. The transporter weighs about 200 kg. giving a bearing pressure less than 0.2 kg. per sq.cm. (26). The experimental performance is 20% of the theoretical values using projectile equations. The reduction in distance is on account of the air resistance acting against the throw of salt particles.
The drawbacks of the above noted "Mechanical Salt Transporter" are given below.
The salt transportation problem explained earlier was attempted to solve by flying/throwing principle. With this, salt found spreaded form from one place to another instead of accumulated collection. Moreover it is an energy intensive method for a cheap product like raw salt.
linear speed in a frame which can be used in full length of about 1.5 to 3 mtrs. by removing the head end portion. The conveyor belt is also in two parts (24) to suit this system. The conveyor belt and frame are mounted on a cubical structural frame containing a 6 kw air cooled engine (25) to provide power to the belt conveyor through a gear box. The whole mechanism described above is fitted in such a way on a flat trailer with cylindrical wheels as to turn through 180° to a point to the back or either sides of the salt harvester. During trial it has been found that at an angle of 45° the salt was thrown to a distance of about 13 meters and at 30° to a distance of 10 meters. The transporter weighs about 200 kg. giving a bearing pressure less than 0.2 kg. per sq.cm. (26). The experimental performance is 20% of the theoretical values using projectile equations. The reduction in distance is on account of the air resistance acting against the throw of salt particles.
The drawbacks of the above noted "Mechanical Salt Transporter" are given below.
The salt transportation problem explained earlier was attempted to solve by flying/throwing principle. With this, salt found spreaded form from one place to another instead of accumulated collection. Moreover it is an energy intensive method for a cheap product like raw salt.
In Fig.5 of the drawings is shown a schematic diagram of a "Tractor driven mechanical salt harvester TD-2". A report by R.P.Dhiman and Dr.A.S.Kane and "Tractor driven mechanical salt harvester" by Dr.A.S.Kane, published in Salt Research & Industry, Vol4, No.l, Jan. 1967, p.22. This is a patented device No.l 11847 dt. 7-Aug-1967 by Dr.A.S.Kane and H.N.Patel both of Central Salt & Marine Chemicals Research Institute, Bhavnagar, constituent laboratory of Council of Scientific & Industrial Research and Indians.
This harvester device is operated by a tractor. It consists two floating buckets holding belt conveyors (26) side by side. Top ends of the conveyors are away from the tractor, its lower ends carry carbon steel scraping blades (27) each 60 cm wide and spaced apart by a span of 60 cm, leaving blank belt of salt layer in between the two cut strips. Both the blades are provided with the rotors (30) to pass the scraped salt into the buckets of the belt conveyors. The cutting depth of salt layer is controlled by the top links and other screwed lever adjustments. The harvester is liftable by the hydraulic systems of the tractor. The harvesting capacity is 20 ton/hr. (28). The trials were conducted at M/s. United Salt Works, Kandla and at Experimental Salt Farm, Central Salt & Marine Chemicals Research Institute (CSMCRI), Bhavnagar. An unraked salt layer of 5 cm. thickness has bearing
strength of 1 kg./sq.cm. This is based on the tractor tyre filled with that pressure and doesn't sink into the crystalliser bed. The use of the harvester is advisable for the salt farms producing min. 25000 tons of salt per year. The total weight of the harvester is 460 kg. There are two supporting drums (29) at the rear end of the harvester. A trailer (36) of 2 tons capacity was attached behind the harvester. Here power with its transmission worked well. The scraped salt layer (35) was approximately 2.5 cm thick.
The drawbacks of the above noted "Tractor driven mechanical salt harvester TD-2 and Tractor driven mechanical salt harvester " are given below.
The hauling problem of 10 trailers per hour was required to be managed. The traffic frequency and the salt bed conditions were not made for each other. This created limitation in its extensive use till today. It posed a question what to do after lifting the scraped salt, in a salt bed that itself is not strong enough to withstand repetitive pass.
In Fig.6 of the drawings is shown a schematic diagram of a "Use of mechanical salt harvester in partial harvesting operation of scraping and breaking of hard layer of salt" by B.S.Purabia, Dr. A.S.Kane and Dr.M.HJadhav, published in Salt Research & Industry, Vol.7, No.2 & 3, Apr-July, 1970, p.66,67.
As a matter of conducting trials with limited actions of harvester, both the
belt conveyors (26) of Fig.5 and their lower covers (27) and rotors (30) as well as trailer (36) were diassembled. Hard unraked salt layer of 10 cm. thickness (37) was then scraped in the crystallisers of M/s. Saurashtra Salt Mfg. Co. at Porbandar, Gujarat for 17 whole days. The bearing strength of the crystalliser bed was 1 to 1.5 kg. per sq.cm. The scraping capacity of 35 HP tractor was measured as 80 tons of salt per hour (33) by consuming 1.5 litre diesel fuel. The trials for three days were also conducted at M/s. Saurashtra Chemicals using complete assembled harvester. The need was felt to develop the suitable transportation device.
The drawbacks of the above noted "Use of mechanical salt harvester in partial harvesting operation of scraping and breaking of hard layer of salt" are given below.
The limited scraping portion of the device shown in Fig.5 ((27) was tested by using both the blades. It produced loose salt with big salt lumps without shifting its location. These lumps are required to be reduced in size before washing or during stacking as they fall back from the steep belt conveyor and harm the workers. Not only that manual collection of it from the crystalliser itself is an ardous task left behind.
In Fig.7 of the drawings is shown a schematic diagram of a "Cover elevator salt harvester" by B.S. Purbia, published in Salt Research & Industry, Vol.4, No.2, Apr., 1967,p.55.
This harvester was a tractor operated portable device. A scraping blade (38) was 2 mtr. wide. The raked salt is scraped and lifted by the buckets carried by the 2 mtr. wide belt conveyor (39). It discharges towards the tractor side on a horizontal belt conveyor (40) extended to its one side to facilitate it for dumping into a trailer running parallel to the harvester. The loaded trailer travels on unscraped salt bed surface. The weight of the device is toward the tractor wheels, and favourable rotation of conveyor does not allow salt to accumulate in front of the blade.
Long scraping blade could not scrap the hard salt layer successfully and uniformly. Trailer traffic frequency still remains a problem.
In Fig.8 of the drawings is shown a schematic diagram of a "Mechanical harvesting of salt" by R.A.Parikh of Tata Chemicals Limited, Mithapur, Gujarat, India, published in Salt Research and Industry, Vol. 1, No.2, July, 1964, p. 19.
The pans of 5 acres (330 m x 53 m) is recommended as a fixed size for harvester to work as shown in top plan (50). Nearly 7.5 cm. unraked and drained
salt layer is allowed to crystallize. It is loosened first by the tractor operated rotating cutter (41). The function of this harvester is to scrap/collect (42) the loosened salt, lift it (43) and convey (44) upto the trailer (45) standing outside the pan. The harvester weighed about 10 tons and supported by 7 crawler wheels (46). A 26.5 mtr. long structure (47) of 1 m x 1.3 m. cross section area carries belt conveyor. A scraping trolley (48) travels to and fro on the rail mounted on long structure and the support wheels. The belt conveyor end near the bund dumps salt into a drag elevator (49) that lifts and further dumps into a trailer. After harvesting half the pan lengthwise other half of the pan is harvested by turning 26.5 mtr. long structure at 180° inside the pan. After harvesting the entire pan it turns 90° and crosses the bund of 0.3 mtr. hight with sufficient slope. A need to increase the harvesting capacity was felt at the time of approaching monsoon season.
The drawbacks of the above noted "Mechanical harvesting of salt" are given below.
Indian salt works have the crystallizer pans of different sizes, whereas the developed device has applicability only with the specific size of the pan. Moreover, the structure of this harvester was heavy and long one to transfer in the pans, or
outside on platform or to shelter it in the salt works. Its maintenance was costly, time consuming and difficult.
In Fig.9 of the drawings is shown a schematic diagram of a "Mechanisation in salt production - with an observation of an existing salt harvester in the year 1997-1998" by K.M.Majeetia of Central Salt & Marine Chemicals Research Institute, Bhavnagar, constituent laoratory of Council of Scientific & Industrial Research, published in Salt Research & Industry, Vol.10, No.2, Sept., 1974, p.29.
The collected information is from the report as well as from the observation of the existing salt harvester at Central Salt & Marine Chemicals Research Institute.
It is an articulated assembly of three chain conveyors (51,52,53) and inclined blade (54) with seven tines (55) mounted on a frame supported on two pneumatic rear wheels (56) 0.75 m diameter and a peg (57) as central support in the front. The whole frame is drawable from the middle front point by a single rear pulling pivot of
the tractor. The power is taken from the power take off shaft of the tractor. The steel blade 1.5 m wide scarps the salt layer followed by the scarifying penetration of 7 tines. The blades scrap raked/unraked salt layer and push it into the drag conveyor (51) that discharges salt on a horizontal 0.3 m wide transversely placed chain mounted staggered belt conveyor (52) at a height of 0.75 m above the bed. The
third is also 0.3 m wide inclined bucket mounted belt elevator (53) that dumps salt into the trailer (58) through a chute. The capacity of the harvester is 50 tons/hr. The weight of this harvesting device without engine mounted on it is about 1 ton. It has also been calculated in the year 1974 that the expenditure by manual harvesting of Rs.2 per ton will come down to Rs. 1.3 per ton of salt by employing this device.
The drawbacks of the above noted "Mechanisation in the salt production -with an observation of an existing salt harvester in the year 1997-1998" are given below.
The device is not manoeuverable type as the harvester is drawable only. The assembly of 18 sprockets and 9 link chains demand frequent maintenance. Salt transportation problem is similar to the one explained earlier considering the medium size salt works.
In Fig. 10 of the drawings is shown a schematic diagram of "An evolution of harvesting methods and mechanisation in small salt works " by M. Rocha, E. Regato and F. Almeida, Portugal, Pb.Fifth International Symposium on Salt Vol.2, 1966, Northern Ohio Geological Society, p.367-370. The diagram is drawn from the description given in the original text.
Harvesting consists of removing the crystals from the location of their precipitation. The salters soon verified that this operation was one of the most significant in the productive process, later on, they would learn it was the hardest and most expensive one. Ultimately the industrial revolution reached the salt ponds by the introduction of mechanical procedures, able to perform the operations with a minimum of human effort. Harvesting still holds an important position because a great percentage of the expenses are incurred during its completion.
Stages of harvesting: Residual brines are drained (61). The salt layer is extracted, broken up and separated from the bottom (62) and elevated (63). The salt is then first removed (lateralized) (64), Loaded on containers or vehicles (65), Moved again and transported to Washing, from there moved to (67) again and finally piled (68).
Explaining further, salt layer is removed with the width of the attacking blade. The dragging harvesting methods require a fractioning using a hollow or an adapted rotary cultivator (62) with special teeth. After this salt is carried to the border of the pond, by dragging or by utilisation of containers, vehicles or belt conveyors, (containers are baskets, hampers, basins, buckets etc. and vehicles are trailers, trucks, lorries, dumpers etc.) when containers or vehicles are used the salt
is carried to the pile or washing machine. In other cases, the salt is dragged or raked to the borders of the pans, accumulated there and stays there some time. The dragging methods are solutions specially adaptable to small salt works and to those where the bottoms have low traffic possibilities. They consist in lateralizing the salt, employing a drag set, pulled by a winch (66) on the pond border (64). The drag set may be provided with a motor/tractor, where rear movement is manual. Transport vehicles are loaded with a retroescavator and pulled on trailers attached to farming tractors. The dragging plate is 2.3 m x 0.5 m (69). Beside the system which uses a retroescavator bucket, a helicoidal screw and conveyor belt are also used. To load vehicles with salt heaped on borders, the helicoidal screw and small conveyer belts are employed. These are fed when necessary, with shovel operators. The aim of the technological methods suitable to small salt works still has to be considered in an experimental phase. New adaptable solutions are foreseen.
The drawbacks of the above noted "Evolution of harvesting methods and mechanisation in small salt works " are given below.
Salt layer is loosened first by a harrow or cultivator then is dragged by a plate 2.3m x 0.5m and wire rope using motorised winch, placed on platform. Trailers are loaded by using screw or belt conveyor. Here collection (lateralization) is not a
continuous one, it is reciprocating type movement that has its own mechanical disadvantages. The method compared to other machines engages more number of workers.
In Fig. 11 of the drawings is shown a shematic diagram of "A General practice of manual salt harvesting" which is based on the experience in Experimental Salt Farm of Central Salt & Marine Chemicals Research Institute (CSMCRI), Bhavnagar, constituent laboratory of Council of Scientific & Industrial Research (CSIR).
The crystallizer sizes are 122 m x 38 m (400 ft x 125 ft). The 25 mm (1 inch) thick raked salt layer of a pan is scraped by 33 workers in 5 hours forming 33 heaps (71). All the heaps are allowed to drain and the collection becomes 100 tonnes. They are transferred manually and dumped into the trailers standing outside the pan by carrying it as head load by walking on hard angular salt crystals. Some of them suffer from boils and other skin diseases resulting from constant irritation due to prolonged contact their feet have with salt and brine in pans. The wooden plank (72) is placed on the bund to cross it with head load. The trailers have four tons haul capacity (73) In nutshell the workers attend the following tasks in the salt farm. Preparation of pan beds (77) formation and maintenance of bunds and channels
(76) the regular raking work of crystallised salt (78) scraping of salt and formation of heaps (71) loading the trailers, closing and opening the feed mouths of brine flow (75) feeding the conveyor hoppers (74) digging the stacks and/or loading the trucks (79), etc.
Generally the following mechanical equipments are used in salt works; Rear wheel drive diesel tractors, dumpers/loaders, trailers, belt conveyors, slurry pumps, diesel engines, and trucks. The following manual tools are also used: Soil stabilizing rolls, pickaxes, shovels, baskets, rakers, etc.
The production of salt is increasing gradually in India. The available salt farm condition and the mechanical designs developed abroad could not match each other for years. As a result there prevails a feeling of high time to develop an adaptable mechanical design to work in the widely scattered medium size salt farms of India. Providing potable water from far end to the workers is also becoming a difficult problem.
The drawbacks of the above noted "A General practice of manual salt harvesting" are given below:
Any hard work done manually will not have productivity gain. Large gang of workers impose management problems. Parallel season of agricultural work in
India creates poor availability of trained workers willing to do the cheap work under extreme working conditions. Global price competition does not favour the method.
In Fig. 12 of the drawing is shown a schematic diagram of "The salt extraction equipment mounted on MTZ tractor". Book: Technologia De La Sal Marina by Abilio Garcia Merlot (The Marine Salt Technology, Spanish), p.219, Pb.Ministerio De Mineria Y Geologia La, Habana, 1977.
It is a tractor mounted design of salt harvester moving reverse (81). A screw with blade (82) passes accumulated salt into a bucket mounted belt conveyor (83) that ultimately dumps into a horizontal conveyor (84) which is collected by a forward driving trailered tractor (85).
The drawbacks of the above noted "The salt extraction equipment mounted on MTZ tractor" are given below.
The device is similar to the one developed earlier in India (see Fig.7). It is heavy, difficult to maintain and requires more than 75 mm thick salt layer to operate.
In Fig. 13 of the drawing is shown a schematic diagram of "The agricultural equipment adapted for chopping of salt layer", pp.220 of the same above referred Spanish book..
It is a ploughing teeth implement attached behind the tractor on a beam in helical form that works in the salt layer for loosening purpose when tractor moves in the reverse direction.
The drawbacks of the above noted "The agricultural equipment adapted for chopping of salt layer" are given below.
It is a tractor mounted salt loosener and not a harvester as it does not remove the crystals from the location of their precipitation.
In Fig. 14 of the drawing is shown a schematic diagram of "The combined self driven salt harvester", p.222 of the same above referred Spanish book.
A crawler wheel type tractor is developed in a way to perform as a harvester. It has a screw (86) and a guide roll (87) in front to pass salt to both sides of drag conveyors (88) that dumps into a horizontal belt conveyor (89) that again dumps into a tractor attached trailer (90) moving in forward direction.
Here two types of design capacities are described:
(Table Removed)
The drawbacks of the above noted "The combined self driven salt harvester" are given below.
It is a heavy and high capacity harvester for large size salt works, and less likely to find application in India for want of crystallizer conditions. As the proposed transportation style will damage the bed or will need to sacrifice a thick left out salt crop, by changing the level of the salt farm layout.
In Fig. 15 of the drawings is shown a schematic diagram of "Harvest of solar salt at Salin-de-Giraud, France" by P.de Flers, B. De Saboulin & J. Clain, Compagnie des Salins du Midi et des Salines de Test, 51 Rue d'Anjou, 75008, Paris, France. Book: Salt Symposium, Part 4th, (1966), Vol.2, p.408.
The solar salt works covers an area of 11000 hectares (27170 acres as 1 hactare = 2.47 acres). The average salt production amounts to 900000 tonnes. The harvesting rate is 30000 tons per day. This goes for about 30-35 days. The blade of 3.8 m width (91) advances at a speed of 30 to 60 m/min. by cutting 90 mm thick salt layer. The salt production rate is 1500-1600 tonnes/hectare/hr. minimum. The cut layer falls on internal face of the conveyor (92) which in turn deposits the salt on a second conveyor (93) that removes the salt outside. The harvesting device is fitted
to a conventional caterpillar tractor (95) the width of which is such that the tread pressure of the equipment is approx. 0.5 kg. per sq.cm. A harvesting site is composed of two salt harvesters, several aligned horizontal self propelled belt conveyors having 50 m unit length (94) and a belt elevator for the stock piling (96). Only 12 men are required for operation of all the equipments.
The drawbacks of the above noted "Harvest of solar salt at Salin-de-Giraud, France " are given below.
The device will not be suitable for medium size salt works of India due to the problems of its heavy capacity.
There are few other large capacity harvesters working in the salt works world over. Since here we are more concerned with the smaller capacity devices for medium size salt works, their descriptions are not included.
Each harvester requires to sacrifice the initial salt crop layer temporarily or permanently. Heavy harvesters need heavy amount of left out salt crop. The temporarily left out crop that comes to about 20 to 30 per cent of the total considering the present design may be collected manually, at the end of the season. This stands as substitute to a brick lined and stablised crystallizer bed, for attaining the required bearing strength, to run the device. The presentation of detail
description of all the prior arts is as follows. All the figures drawn are schematic line drawings just to explain the working principles of the main components without showing structural or assembly details to any scale. The numbers/ alphabets shown in brackets are referred from the respective figures.
The main object of the present invention is to provide a device useful for harvesting/ridging of salt/soil which obviates the drawbacks as detailed above.
Another object of the present invention is to provide a device to form soil ridges to develop salt farms, where channels, bunds and pan beds are formed with the help of the suitable salt/soil ridger.
Still another object of the present invention is to provide a device capable of extending the scraping and conveying function for a long horizontal distance, using a mobile power source from outside the pan, which helps in conveying predominant ridger device to do the job of transporter.
Yet another object of the invention is to dump the ridged material into an integrated container placed above the mobile power source (tractor etc.), having hydraulic hauling advantages used intermittently,and thereby performing scraping, conveying, lifting and hauling the ridge of salt/soil.
In Figure 16 to 18 of the drawings accompanying this specifications the schematic diagrams of the parts and assembled device of the present invention are shown.
Fig. 16 of the drawing shows helical screw, a part of a screw conveyor, of the device having one or more helixes. Fig. 16(i) shows the elevation and Fig.l6(ii) shows the end view.
Fig. 17 of the drawing shows the cover/trough of the helical screw, a part of a scew conveyor, of the device. Fig.l7(i) shows the elevation. Fig.l7(ii) shows the end view and Fig,17(iii) shows the top view.
Fig. 18 of the drawing shows the assembled view of the present invention. Fig. 18(i) shows the end view. Fig. 18(ii) shows the elevation.
Accordingly the present invention provides A device useful for harvesting/ridging of salt/soil, which comprises one or more helical screw conveyors (a) mounted on a horizontal shaft (b.c), the helical screw conveyor being provided at one end with at least half turn of reverse helical screw (e) the said helical screw conveyor periphery being also provided with teeth (d) capable of cutting salt/soil layer, the said helical screw conveyor mounted on horizontal shaft being encases in an open bottom trough/cover (f) having ground support, the cover being provided
with front inlets (h) and a rear outlet (g) at the reverse helical scew (e) end, the said cover (f) being provided at lower following edge with a scraping blade (i) and a baffle (j) at the front, the said horizontal shaft (b) ends (c) being provided with known means (k,l,m) for coupling with a known prime mover. Scraping depth controlling pads (n) is provided to support the trough.
In an embodiment of the present invention the helical sqew conveyor used may be such as single or multistart helix.
In an another embodiment of the present invention the known means used for coupling the shaft ends to a prime mover may be such as chain, sprockets, pulleys, gears, couplings and clutches.
In yet another embodiment of the present invention the prime mover used may be such as tractor, crawler, loader and dumper.
In figures 19 to 23 of the drawings the use of the device of the present invention is shown.
Fig. 19 shows the side view of the device of the present invention attached with the tractor.
Fig.20 shows the top view of the device of the present invention attached with the tractor.
Fig.21 shows the path of the movement of the device of the present invention along with the tractor from top view.
Fig.22 shows the cross sectional view of the crystalliser.
Fig.23 shows the path of the movement of the device of the present invention along with the tractor from top view.
An embodiment of the use of the device of the present invention is detailed below:
The tractor operated salt farm ridger (harvester) which uses a mobile power source like agricultural farm tractor (101), loader, etc. to which device like the ridger (102) can be attached in a way to make it rotating at a certain place, level, route, speed and arrangement with respect to the level of mobile power unit or to the level of the salt/soil bed (103) to work upon, as to scrap or loosen the required depth of the raked/unraked salt/soil bed (103) by adjusting the dummy support wheels and or sliding foot plate, (116) hydraulic control, top link etc. and convey the same scraped salt/soil material simultaneously and or the previously scraped and accumulated material (104) together to either side (105) of the entire ridger length or may also be lifted above the salt/soil bed as second alternative to work as loader or transporter, with the help of no workers or few workers, as per the expected duties of the ridger, that always travels transversely i.e. in the normal direction to its length, maintaining contact with the salt/soil bed while it performs, that may or may not be liftable by itself or by means of hydraulic/pneumatic devices. The implement moves with mobile power unit in straight/spiral suitably to form salt/soil ridges (107) and to transfer the salt/soil with/without hauling facilities. The pneumatic tyre wheels of the tractor/mobile power unit may be twin or tripple with minimum tire tread lug height to suit the bed strength. The ridger is an attachable modified design of a screw conveyor carrying two components mainly as
conveyor screw (108) and its trough (109) assembled to perform as ridger, which is also an activity of salt harvester by definition. The said screw has suitable diameter & length having selective materials to resist corrosive and abrasive working/ conditions. The screw has right or left hand multistart helix of suitable angle witH plain and close blade (flight) configuration. The cutting sharp teeth (110) are place all around the helix blade edges. The screw shaft may be solid, hollow or flexible fully or partly in a single or several aligned unit length each of appx. 2 to 3 m size The trough may be cylindrical/polygonal (109) made up of perforated/unperforatedl sheet, withjjuitable mouths to perform in dry or wet conditions. Each unit length of! the screw has always a lengthwise open slit (111) at the bottom to establish contact
with the bed and scraping blade (113) fitted to it. There is also a provision for brine controlling baffles (112). It also carries ultimate inlet (114) and outlet (115) mouths. The transverse trough is rigid enough to withstand against draw-bar pull during straight and turning movements of the tractor.
The principal use and innovative aspect of the device of the present invention is to form ridges of salt/soil in the salt farm by a combined action of scraping and dragging (lateralizing) of the bed and to form ridges (107) at an approachable distance from the bund.
Description of the device of the present invention is detailed below: The device is mounted on three point linkage of a tractor and is hydraulic controlled. The liftable implement consists a single unit of screw conveyor (ridger) attached transverse to the direction of tractor travel of suitable length, diameter and shape to perform the duties of scraping and conveying. The screw has multi-start flights of suitable angle. It carries scraping teeth all around to the edges of the flights. Another straight blades at the bottom of the trough are for scraping and or accumulating salt/soil. There is also a baffle attached to the trough to facilitate the working with the wet salt/soil. There are outlet and inlet mouths at the ends of the trough one opposite the other, the openings are of heap shape suitable for forming
the ridge work. The screw and the trough are assembled by means of two end bearings. The screw conveyor is rotated by the tractor power take off shaft at a required speed by means of using sprockets, chains, gear box, universal joints and line shaft. They are all supported by the trough and the tractor.
The cutters fitted on the screw conveyor are pieces of hard steel straight stripes, radially erect at equi-distance, keeping flat plane perpendicular to the axes of screw shaft, and fixed on the non-pushing face of the screw flights. Their cutting edge ends/teeth are sharpened.
The trough has a lengthwise open slit to establish contact of the screw with the bed to be scraped. The scraping depth is adjusted in proportion to the power of the tractor in use.
The two adjustable flat base plate (116) are provided on the outer ends of the trough to control and maintain the depth of scraping. The material is selected to resist corrosive and abrasive working conditions. Lubrication to working parts is provided.
The operation of the device of the present invention is detailed below:
The place shown as point (106) is from where the ridger starts functioning in the crystallizer pan. The depth of cut is adjusted as explained earlier. A /small ridge is formed in the beginning. In the diagram the spirally travelling line indicates the path of the ridge that simultaneously being wiped out from inner side and forms the higher size ridge ahead as seen at the point (104,105) on outer sides.
After reaching the capacity of the ridger to its maximum at point (117) or around the ridger is adjusted to stop cutting and does the job of conveying only and it continues travelling spirally till the formed ridge (117) is dragged close to the bund, by moving and touching just above the bed surface upto (107,118).
The ridger starts scraping work again from the point say at (117), and continues till it reaches to its maximum capacity. Repeatatively thus the number of large size ridges are formed beside the bund (119). The number of ridges depends on the capacity of the ridger i.e. the max. amount per unit length, the depth of cut, the size of the pan and the wetness of the salt/soil. The above explained length of scraping path may be called a pass. The passes may be arranged as one or more in a pan by adjusting the depth of cut till to the place closer to the bund.
Fig.22 & 23 shows alternative methods of travelling the device inside the crystallizer. In case of spiral path the device starts from the middle, whereas for zig¬zag path it begins from one corner of the crystallizer. Spiral path is easy and more preferable.
Fig.21, 22 & 23 explains the details of the field experiment of the present invention for the purpose of forming ridges of salt.
The following examples are given by way of illustration of the present invention and should not be construed to limit the scope of the present invention.
Example-1
The device of the present invention was mounted on the three point linkage of the 35 HP tractor. The length of the screw conveyor is wider than the width of the tractor. Power take off shaft end is connected to the ridger driving shaft by means of universal joints. The screw rotates at a speed in proportion to the tractor travel. The scrapable depth of layer is controlled by operating hydraulic system of the tractor, adjusting the sliding foot plates and the top link length. The ridge forming capacity is measured to 30 tons/hour. The measurement relates to the largest size of the ridge formed during the experiment.
Examplc-2
The device of the present invention was tried in wet salt conditions, with small quantity of brine available in the crystallizer. The salt scraped and moved
sideways got agitated with adhering brine and got partially washed to remove chemical impurities, magnesium in particular. The brine control and salt washing performance is yet to be confirmed in full chemical analysis. But a visual evidence of improved whiteness was noted. The functional test was found quite satisfactory. The capacity measurement was not carried out on account of wet conditions and rainy season during the trial.
Example-3
The device of the present invention was mounted on 45 HP diesel tractor and the ridge forming capacity was measured to 40 tons/hr.
In all these experiments the layer of salt is about 50 mm thick in the pan and the ridger scrapped about 13-15 mm depth of the unraked salt layer in the beginning.
Example-4
The device of the present invention was tried for forming soil ridges. It worked successfully and found no challenge in its performance. The capacity measurement is omitted for the time being to concentrate more on the salt scraping performance. But in no case found visually less than the capacity of salt.
The main advantages of the present invention are as follows:
1. It is light weight, simple, easy to operate, maintain, manoeuverable, portable and
cheap for the cheap material like salt/soil with the mechanical facilities available
at the remote places of medium sized salt works.
2. The maximum left out salt crop is not more than 20% of the total production in a
season.
3. The function of the ridger is such that the traffic across the pan is most limited,
say as only two times during harvesting or formation of ridges of one crop of a
pan.
4. A tractor driver with an attendant is sufficient to work with the device, and to
bring the salt near the bund.
5. The ridger device contributes to the size reduction of salt/soil by scarifying the
layer inspite of working with the raked/unraked bed. This is favourable for
washing and stacking of salt.
6. The ridge formation work of salt in presence of washing brine contributes to the
upgradation of salt automatically, since the screw has inherent functional
advantage of intensive solid liquid mixing and separating to leave behind the
physical and chemical impurities of salt of the scraped bed. The residual
draining also takes place after forming ridges. The washing action is performed almost without any further facilities and investments.
7. The salt production quantity is increased as a result of clearing the pan faster
and to start with the earliest evaporation/concentration work.
8. The ridge formation of soil is also a hard work like salt if attended manually.
This implement performs excavating and transferring farm soils to develop the
pans and to form the bunds, channels etc. This is applicable to both salty as well
as fertile type of soil.
9. The product salt price comes down, on account of the efficient productivity
offered by the device.
10.The salt bed left undisturbed bottom due to this bearable, carefully planned vehicular traffic inside the pan, by the device.
11 .A portable ramp like facility is sufficient for the entrance of the implement in the pan.
12.An additional vertical conveyor and a container contributes to the material hauling facilities by dumping the ridge of salt/soil into self mounted integral container, since the material accumulation begins from the lowest level of the implement. This does not require any parallel source of power (say for example a
tractor) carrying container and running beside the ridger, as is the case with most of the harvesters. The container is emptied hydraulically intermittently.
13.The short screw conveyor (ridger) is a scraping predominant device. Similarly long assembled screw conveyors (ridger) provide a conveying predominant device. The second device is suitable where scraping power requirement is negligible, e.g. Baragara (large loose crystalline) salt/soil.
14.The device of the present invention provides an answer to the problem of salt harvesting by mechanical means for the medium size salt works of India and abroad which was carried out uptill now manually and uneconomically.

We Claim:
1. A device useful for harvesting/ridging of salt/soil, which comprises one or more
helical screw conveyors (a) mounted on a horizontal shaft (b.c), the helical screw
conveyor being provided at one end with at least half turn of reverse helical screw (e)
the said helical screw conveyor periphery being also provided with teeth (d) capable
of cutting salt/soil layer, the said helical screw conveyor mounted on horizontal shaft
being encases in an open bottom trough/cover (f) having ground support, the cover
being provided with front inlets (h) and a rear outlet (g) at the reverse helical screw
(e) end, the said cover (f) being provided at lower following edge with a scraping
blade (i) and a baffle (j) at the front, the said horizontal shaft (b) ends (c) being
provided with known means (k,l,m) for coupling with a known prime mover.
2. A device as claimed in claim 1, wherein the helical screw conveyor used is a single or
multistart helix.
3. A device as claimed in claim 1 and 2, wherein the known means used for coupling the
shaft ends to a prime mover is selected form chains, sprockets, pulleys, gears, clutches
and universal joints.
4. A device as claimed in claims 1 to 3, wherein the prime mover used is selected from
group consisting of tractor, crawler, loader and dumper.
5. A deice useful for harvesting/riding of salt/soil substantially as herein described with
reference to the examples and drawings accompanying this specification.

Documents:

1678-del-1998-abstract.pdf

1678-del-1998-claims.pdf

1678-del-1998-correspondence-others.pdf

1678-del-1998-correspondence-po.pdf

1678-del-1998-description (complete).pdf

1678-del-1998-drawings.pdf

1678-del-1998-form-1.pdf

1678-del-1998-form-19.pdf

1678-DEL-1998-Form-2.pdf

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Patent Number

216547

Indian Patent Application Number

1678/DEL/1998

PG Journal Number

13/2008

Publication Date

28-Mar-2008

Grant Date

14-Mar-2008

Date of Filing

18-Jun-1998

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH.

Applicant Address

RAFI MARG,NEW DELHI-110001,INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	HARGOVIND NANDLAL PATEL	CENTREL SALT & MARINE CHEMICALS RESEARCH UNSTITUTE,BHAVNAGAR-364002
2	SUDHIRBHAI LAXMANRAO BHAT	CENTREL SALT & MARINE CHEMICALS RESEARCH UNSTITUTE,BHAVNAGAR-364002

PCT International Classification Number

A01D 9/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA