Title of Invention

A COMPOSITION FOR MAKING SLURRY EXPLOSIVE USEFUL FOR PERIMETER BLASTING IN TUNNELING

Abstract

This invention relates to a composition for making small diameter cap-sensitive slurry explosive useful for perimeter blasting in tunneling and other excavation works and a process for preparing the said slurry explosive. The synergistic composition utilizes ingredients of oxidisng agents such as Ammonium nitrate, Sodium nitrate, reducing agents such as Aluminium powder , sugar, guar gum,urea, thio-urea, coolants such as Water, Sodium chloride, Cross-linking agents such as potassium dichromate.potassium pyroantimonate and sodium nitrite as gassing agent to produce zero oxygen balance to provide small diameter cap sensitive slurry explosive.

Full Text

This invention relates to a composition for making small diameter cap-sensitive slurry explosive useful for perimeter blasting in tunneling and other excavation works and a process for preparing the said slurry explosive. At present 25mm-diameter nitroglycerine (NG) explosives are available for use in perimeter blasting and other rock excavation works. The velocity of detonation and detonation pressure are very high resulting in high shattering effect, which damage adjoining rock mass. The density varies from 1.10 to 1.30 g/cm 3. Ref. Encyclopedia of Explosives Vol. 9, pp T415. The NG based explosives are highly sensitive to impact and friction, thus there is increased danger during operation. The fume quality is poor and causes nausea/Reference may be made to James Taylor and P. F. Gay "British Coal Mining Explosives," pp. 28-29. Internationally, small diameter slurry explosives are available in 22mm, 25mm, 32mm 37mm and 45/50mm with different weights and according to the diameter the cartridge material is plastic tube with copper clip or blow molded tube. Reference may be made to: Engineering Index Annual -1993, Vol. 92, Part III, Development in explosives (050974). These are cap sensitive compositions and the velocity of detonation varies from 4000 to 6000 m/sec in confined underground areas with higher density and strength. Number of Canadian Patents were filed for small diameter explosives and are commercially available. The details are as follows: (a) GOMA 2E-COSD is a small diameter nitroglycerine/nitroglycerine based explosive available in 32mm diameter cartridge with higher density, 1.48g/cm3 and acceptable for underground use. The velocity of detonation of this product is 5200 m/s in confined condition (Ref. ETI Canada Inc., © 1998-2000). (b) TO VEX ®MINERITE ™ -499 is a low incendivity watergel cartridge explosive, specially designed for underground use where a possible danger of sulphide dusts ignition exits. This product is available in 32mm diameter with density 1.13 g/cm3 and its velocity of detonation is 4400m/s (Ref. ETI Canada Inc., © 1998-2000). (c) TO VEX ® MINERITE™ 2 is another Canadian patent a small diameter cap sensitive cartridge explosive designed for underground use and available in 32mm diameter cartridges with density 1.20g/cm3 and its velocity of detonation is 4000m/s. The aluminized watergel is effective where maximum energy and transient pressure resistance are required to the rock fragmentation (Ref. ETI. Canada Inc. © 1998-2000). (d) TOVEX ©MINERITE 3 is a small diameter watergel cartridge explosive designed for underground use. This is aluminized product and is available in 50mm diameter cartridge. The density of this product is 1.18g/cm3 and its velocity of detonation is 4800m/s in confined (Ref. ETI Canada Inc., © 1998-2000). (e) RIOGEL EP is a amall diameter watergel explosive and available in 32mm diameter cartridge. The density of this product is 1.10g/cm3 and its velocity of detonation is 4500m/s. This is applicable in underground mines where high energy is required (Ref. ETI Canada Inc., © 1998-2000). (f) TOVEX ® LOADER™ is cap sensitive small diameter cartridge watergel designed for use with pneumatic loader. This is available in 32mm diameter cartridge and density is 1.20 g/cm3. The velocity of detonation of this product is 4000m/sec and it acceptable for underground use (Ref. ETI Canada Inc., © 1998-2000). (g) TROVEX ® EL -930™ is a booster sensitive repumpable watergel suitable for use in boreholes 50mm and larger. The density of this product is 1.30 g/cm3 and its velocity of detonation is 6000 m/sec (Ref. ETI Canada Inc., © 1998- 2002). The Canadian explosives referred herein above are available in 32 and 50mm diameter cartridges and the velocity of detonation and detonation pressure of product are very high in the range of 4000 to 6000 m/sec, which damages the adjoining rock masses. These are only suitable for hard rocks and can give adverse result i.e., damage the adjoining rock in tunnel and perimeter blasting. The GOMA 2E COSD is nitroglycerine based explosive which also has safety and health hazardous problems during operation. Indomite from IBP Co. Ltd, India, is a small diameter explosive commercially available in 25mm, and 45/50mm diameter cartridges. The density of this product is 1.15 to 1.18 g/cm3. The velocity of detonation varies from 4800 -5800m/sec. The velocity of detonation of this explosive and detonation pressure is also on the higher side and the shelf life of this product is poor and hence gives poor detonation. In US Patent No. 5507892/1996, Zabaia, et ai. have prepared an explosive composition suitable for cartridging in paper and given its method of manufacture. According to the invention a watergel explosive composition contains an oxidizer salt, a sensitizer, a thickener, a cross-linking agent, a fuel and water. The sensitizer component including more than 50% by weight of one or more water soluble compounds of oxygen balance more positive than -150%, selected from salts of nitric acid, chloric acid and perchloric acid with acylic nitrogen bases, having no more than two hydrogen atoms bonded to each basic nitrogen atom and up to three carbon atoms per basic nitrogen atom, and the salts of nitric, chloric and perchloric acid with a phenyl amine, and the water content being less than 10%, by mass, of the composition. It is available in 26 mm and 32mm diameter cartridges with densities in the range of 1.14 to 1.18 and their velocity of detonation is 2855m/se and 3241m/sec respectively. In this explosive the water % is less than 10%, which may crystallize the explosive during storage and will lose its detonation property. In another US Patent No. 55798477/1998, Givens; Richard W. and Williams; Greg S. invented a small diameter explosive cartridge and a two-stage large diameter explosive cartridge apparatus for pre-splitting rock which can be axially detonated by detonating cord through a central detonation passageway in the explosive cartridge while keeping the detonating cord and the explosive material in the explosive cartridge physically separate. This is available in 67mm cartridge and its velocity of detonation is 55974m/sec. The velocity of detonation of this product is very high and since detonating cord is also attached with explosive cartridge it burns the explosive column and energy of explosive will be affected. When a detonating cord is detonated (lOg/m) the flame length measured were 0.8 ±0.05 m, which burnt the explosive column, and there is loss of explosive energy. In another US Patent No. 5928576/1999, Zimmermann; Leon Michael prepared a cap-sensitive watergel explosive composition product, which contained in range (g/100) monomethylamine nitrate 16-20%, ammonium nitrate 67-73.5%, potassium perchlorate 6%, ground rubber 8-3%, pigment aluminium 0-1% and water 4.4 - 5.0%. It is cap sensitive in 25-26mm diameter and inventor had studied extensively and conducted its impact and friction sensitivity test by Julius Peters Apparatus. In our co-pending Indian Patent Application No. 2642/DEL/96, B. M. P. Pingua, Nabiullah, Jagdish and B. B. Dhar have described and claimed a coal base composition for surface blasting for dry holes. The composition claimed was (g/100) (i) Ammonium nitrate=92.00, Coal powder = 6.4, Guar gum = 0.8, Sodium nitrite = 0.40 and potassium dichromate = 0.4. (ii) Ammonium nitrate =73.6, Sodium nitrate =15.8, Coal powder = 8.8, Guar gum = 1.3, sodium nitrite = 0.2 and Potassium dichromate = 0.3. This explosive composition was in a powdery form and it cannot be used in watery holes due to poor water resistance. In another co-pending Indian Patent application No. 3071/DEL/98, Nabiullah, B. M. P. Pingua, Jagdish and T. N. Singh have described an explosive composition useful for safe blasting of coal and claimed the composition in the range of (g/100) Ammonium nitrate 40.15 to 41.10, Calcium nitrate 13.50 to 14.00, Aluminium (flake grade) 2.50 to 3.00, Sugar 7.30 to 7.40, Urea 1.80 to 2.36, Thio -urea 0.90 to 1.00, Sodium chloride 14.10 to 14.50 and water 18.45 to 19.00. This composition is suitable for highly gassy mine in P-5 conditions for underground coalmines. This explosive composition was detonated in 32mm diameter cartridges and it fails to detonate under the small diameter cartridges like 25mm, 20mm and 17mm diameter. In still another co-pending India Patent application No. 204/DEL/2001, B. M. P. Pingua, Nabiullah, Jagdish and T. N. Singh have described and claimed an explosive composition for cut face blasting in P-3 condition for underground coal mines. The said composition (g/100) comprises in the range of Ammonium nitrate 40.60 to 40.80, Calcium nitrate = 31.30 to 31.40, Aluminium powder = 2.75 to 3.00, Sugar = 8.95 to 9.31, Flour = 1.47 to 1.50, Guar gum = 0.99 to 1.00, Water = 4.30 to 4.50, Sodium chloride = 9.00 to 9.10, Potassium pyro-antimonate =0.04 to 0.05 and Sodium nitrite =0.04 to 0.05. This explosive is suitable for only PS conditions for gassy mine in underground coalmines with higher velocity of detonation and explosion energy. This explosive also fails to detonate in lower diameter cartridges i.e.; 25mm, 20mm and 17mm. The main object of the present invention is to provide a composition for making small diameter cap-sensitive slurry explosive useful for perimeter blasting in tunneling and other excavation works which obviates the above noted drawbacks. Another object of the present invention is to provide a process for preparing a slurry explosive from the novel explosive composition which obviates the above noted drawbacks. Still another object is to provide a synergistic composition for preparing a slurry explosive having low velocity of detonation in the range of 2680 to 3300 m/s; explosion temperature in the range of 1800 to 2000 Kelvin; explosion energy in the range of 1540 to 1670 kJ/kg, sufficient to break the rock with proper fragmentation; and strength of the composition is in between 38 to 42 % of BG. Yet another object of the present invention is to provide a synergistic explosive composition for preparing a slurry explosive useful for mining marble, red sand stone, granite quarry, shaft-sinking, construction of water channel and road which require small diameter and low energy explosive. A further object is to provide a novel explosive composition for preparing slurry explosive which would be cap- sensitive small diameter in 17mm, 20mm and 25mm, with velocity of detonation in the range of 2600 -2700 m/s, 2700 -2800 m/s and 3000-3300 m/s respectively. The small diameter cap-sensitive slurry explosive of the present invention is a novel explosive with low velocity of detonation and explosion energy, which on detonation does not affect the adjoining rock masses. The composition of the present invention is safe in handling and non - hazardous during preparation. The synergistic composition for making slurry explosive of the present invention utilizes ingredients of oxidizing agents such as ammonium nitrate and sodium nitrate, reducing agents such as sugar, guar gum, and aluminium powder, urea, thio-urea, cross linking agents such as potassium dichromate, potassium pyroantimonate or mixture thereof and sodium nitrite as a gassing agent to produce zero oxygen balance to provide a small diameter cap-sensitive slurry explosive. Sodium chloride, as a coolant, was used to retard the explosive parameters like velocity of detonation, explosion energy, explosion temperature and strength. In our earlier co-pending patent no. 2642/DEL/96, the oxidizing agents like ammonium nitrate, sodium nitrate were used in the range of 73.6 to 92.00 wt % and 15.80 wt % respectively. Reducing agents were used in the range of carbon 6.4 to 8.8 weight %. In another co-pending patent no. 3071/DEL/98 the oxidizing agents used were in the range of ammonium nitrate 40.15 to 41.10 weight % and calcium nitrate 13.50 to 14.00 weight % respectively. Reducing agents used were in the range of Aluminium powder 2.50 to 3.00, sugar 7.30 to 7.40, and urea 1.80 to 2.36 weight % respectively. The cooling agents like water and sodium chloride were used in the range of 18.45 to 19.00 and 14.01 to 14.50 weight % respectively. In another co-pending patent no. 204/DEL/2001 the oxidizing agents ammonium nitrate and calcium nitrate were used in the range of 40.60 to 40.80 and 31.30 to 31.40 weight % respectively. Reducing agents used were in the range of Aluminium powders 2.75 to 3.00, Sugar 8.95 to 9.13 and flour 1.47 to 1.50 weight% respectively. The cooling agents used were water and sodium chloride in the range of 4.30 to 4.50 and 9.00 to 9.10 weight % respectively. The above noted explosive compositions failed to detonate in 17 mm, 20mm and 25mm diameter cartridges where as the novel composition of the present invention for slurry explosives detonated in cartridges below 25mm diameter. Comparative ingredients with our present and earlier co-pending inventions are given in table 1. Table 1. Comparative ingredients (g/100) of our Indian patents. (Table Removed) Accordingly, the present invention provides a composition for making slurry explosive useful for perimeter blasting in tunneling, which comprises : Oxidizing agents : (a) Ammonium nitrate 51.80 to 51.60 wt% (b) Sodium nitrate 9.14 to 8.98 wt% Reducing agents : (a) Aluminium powder 2.45 to 2.34 wt% (b) Sugar 7.89 to 7.70 wt% (c) Thio-urea 0.10 to 0.09 wt% (d) Urea 2.45 to 2.40 wt% (e) Guar gum 1.06 to 1.01 wt% Coolant(s)/ Energy depressants : (a) Water 15.10 to 15.00 wt% (b) Sodium chloride 10.52 to 10.20 wt% Cross-linking agent(s) 0.05 to 0.04 wt % Gassing agent (s) 0.05 to 0.04 wt % The oxidizing agent used may be such as ammomium nitrate, sodium nitrate or mixture thereof. The reducing agent used may be such as aluminium powder (flake), sugar, urea, thiourea, guar gum, or mixture thereof. The explosive retardant agent/coolant used may be such as sodium chloride, water or mixture thereof. The cross-linking agent used may be such as potassium pyroantimonate, potassium dichromate or mixture thereof. The gassing agent used may be such as sodium nitrite, Potassium miocynate or mixture thereof. The oxidizing and reducing agents used may be of 99% purity. The cross-linking agents used may be of 99 % purity. The gassing agents used may be of 99 % purity. In an embodiment of the present invention, the synergistic composition may consist of: i Ammonium nitrate 51.80 to 51.60 wt% Sodium nitrate 9.14 to 8.98 wt% Aluminium Powder 2.45 to 2.34 wt% Sugar 7.89 to 7.70 wt% Thiourea 0.10 to 0.09 wt% Urea 2.45 to 2.40 wt% Guargum 1.06 to 1.01 wt% Sodium chloride 10.52 to 10.20 wt% Water 15.10 to 15,00 wt% Potassium dichromate 0.05 to 0.04 wt% Sodium nitrite 0.05 to 0.04 wt% It is a feature of the present invention that the composition is not a mere admixture but a synergistic mixture having properties, which are different to the mere aggregation of the individual ingredients and there is not chemical reaction in the composition. Accordingly the present invention provides a process for preparing slurry explosive from the composition of the present invention, which comprises dissolving oxidizing agents in water at 70-75°C and maintaining pH of the solution in the range 4.40 to 5.0 by adding acid/base, adding to the oxidizing solution so obtained reducing agents such as thiourea, urea, sugar, guar gum and coolants/ energy depressant such as sodium chloride, water to zero oxygen balanced composition in the slurry form, sensitizing the said slurry by using flake grade aluminium powder followed by treatment with gassing and cross-linking agents by conventional methods as herein described to obtain slurry explosive. In an embodiment of the present invention the acid/base used may be such as nitric acid/sodium bicarbonate. In another embodiment of the present invention the reducing agent(s) may be added to the oxidizing solution at a temperature of around 55-56 °C. In yet another embodiment of the present invention the slurry may be sensitized by adding flake grade aluminium powder at a temperature of around 45°C. In still another embodiment of the present invention the gassing and cross-linking agents may be added at the gumming point of the slurry. During the process with aluminium powder no gaseous products are formed, the product formed is A^Os (alumina), which is a solid and heat of formation of A^Os is very high (396 kcal/mol) and the explosive becomes sensitive to detonate withNo.6 detonator, Ref. R. Meyer, pp.13. The composition prepared is sensitized enough to be initiated with copper detonator (No.6) consisting of lead azide, lead styphante, aluminium (ASA) 0.20 gm and pentaerythritol tetranitrate (PETN) 0.22 gm. In the process of the present invention oxidizing agents were first taken with water and heated up to 70-75°C and pH of the solution was maintained in between 4.40 to 5.0 by adding acid/base. It was stirred for at least 5 minutes and reducing agents such as thiourea, urea, sugar and guar gum were added in the oxidizing solution at 55-56°C and at the gumming point the gassing and cross-linking agents added. The formulation was sensitized with the help of flake grade Al powder at around 45°C. This product can be easily transferred into the blow molded tube or polythene tube where the product is completely cross-linked and gassed within 3-4 hours. Slow gassing and cross -linking is always preferable for uniform gassing and good gelling. The following examples are given by way of illustration and should not be construed to limit the scope of the present invention. Example 1. The oxidizing agents such as ammonium nitrate (518g) and sodium nitrate (91.4g) was dissolved in required quantity of water (15 Ig) at 70 ± 5 ° C. Sodium chloride (102g) was added in the oxidizing solution. The pH of the solution was maintained by adding dilute nitric acid at 4.40. At this pH the process of cross-linking and gassing rate is slow and the product is more stable due to the formation of micron size air bubbles. The required fuels such as thiourea (Ig), urea (24g), sugar (77 g) and guar gum (lO.lg) were added to oxidizing solution. The product is near to zero oxygen balanced in the slurry form. The composition is sensitized by using aluminium powder (Flake grade) followed by treatment with gassing and cross-linking agents, sodium nitrite (O.SOg) and potassium dichromate (0.5g) respectively. In a single batch lOOOg of explosive was prepared and its explosive properties were studied. Explosive Properties of Example 1. 1. 2. 3. 4. 5. Sr. No. 6. 7 8. 9. 10. Properties Density Cap-sensitivity Diameter Continuity of detonation Velocity of detonation (i) 25mm (ii) 20mm (iii) 17mm Explosion energy Explosion temperature Impact sensitivity with 10 Kg. fall Hammer Strength Stability test Observation 1.08 No. 6 detonator. 17,20 & 25mm blow molded tube Passed 2700 to 3300 m/sec. 3300 m/s 2800 m/s 2700 m/s 1670kJ/kg 2000 Kelvin 30 kg. m no detonation 42 % BG. More than six month of storage life The prepared explosive was packed in the polythene tube which was cap sensitive at different diameter of cartridges 17mm, 20mm and 25mm and the velocity of detonation was 2700 m/s, 2800 m/s and 3300 m/s respectively. For continuity of detonation the cartridges were kept in a line up to 1m lengths and initiated with No. 6 detonator and found all cartridges were detonated. 10 kg. of weight was dropped by the fall hammer method at the height of 3m and observed 18 no detonation behavior in the explosive. The strength of the explosive was measured by the Ballistic Motor method that was 42% of the BG. The value of explosion energy and detonation temperature was theoretically calculated. The detonation behavior of the composition was tested upto more than six months and detonation was found after six months of storage periods. The oxidizing agents such as ammonium nitrate (517g) and sodium nitrate (90.2g) were dissolved in required quantity of water (150g) at 70 ± 5 ° C. Sodium chloride (103.2g) was added in the oxidizing solution. The pH of the solution was maintained by adding dilute nitric acid/ sodium bicarbonate at 4.80. The required fuels such as thiourea (Ig), urea (24.5g), sugar (78.9g) and guar gum (10.6g) were added to oxidizing solution. The product is near to zero oxygen balanced in the slurry form. The composition is sensitized by using Flake grade aluminium powder followed by treatment with gassing and cross-linking agent, sodium nitrite (0.5g) and potassium dichromate (0.5g) respectively. In a single batch lOOOg of explosive was prepared and explosive properties were studied. Explosive Properties of example 2 1. 2. 3. 4. 5. Sr. No. 6. 7. 8. 9. 10. Properties Density Cap sensitivity Diameter Continuity of detonation Velocity of detonation (i) 25mm (ii) 20 mm (iii) 17 mm Explosion energy Explosion temperature Impact sensitivity with 10 kg. fall hammer Strength Stability Observation 1.10 No. 6 detonator 25mm, 20mm, 17mm blow molded tube Passed 2700to3100m/sec. 3100 m/s 2800 m/s 2700 m/s 1596kJ/kg. 1860 Kelvin 30 kg m no detonation 40 % BG Tested upto six month of storage life The composition prepared was cap sensitive with No.6 detonator in different diameters i.e., 17mm, 20mm and 25mm and the velocity of detonation were 2700 m/s, 2800 m/s and 3100 m/s respectively. Dautich Method and Fiber Optic Method measured the velocity of detonation. The explosive energy and explosion temperature are theoretically calculated. The strength was measured by the Ballistic Motor method and found 40 % of BG. lOKg of weight is dropped from the height of 3m and no detonation characteristics were found in the explosive composition. For continuity of detonation cartridges were kept in a line up to 1m lengths and first cartridge was initiated with No.6 detonator. It was found that all the cartridges were detonated. The values of explosion energy and detonation temperature are theoretically calculated. The oxidizing agents such as ammonium nitrate (516g) and sodium nitrate (89.8g) were dissolved in required quantity of water (150g) at 70 ± 5 ° C. The explosive retardant, sodium chloride (105.2g) was added in the oxidized solution. The pH of the solution is maintained by adding dilute nitric acid/ sodium bicarbonate at 5.0. The required fuels such as thiourea (Ig), urea (24.3g), sugar (78.7g) and guar gum (10.6g) were added to oxidizing solution. The product is near to zero oxygen balanced in the slurry form. The composition is sensitized by using flake grade aluminium powder followed by treatment with gassing and cross-linking agents. In a single batch lOOOg of explosive was prepared and explosive properties were studied. Explosive Properties of example 3 Daurtiche method and Fiber Optic method measured the velocity of detonation of this synergistic composition. They were 3000m/s, 2750m/s and 2680 m/s in 25mm, 20mm and 17mm diameter cartridges respectively. The continuity of detonation test in which the explosive cartridges were placed in a line up to the 1m lengths and first cartridge was initiated with No.6 detonator. It was found that all the cartridges were detonated. 10kg of fall hammer was dropped from the heights of 3m; the explosive has no impact sensitive. The strength of the explosive was measured with the help of Ballistic Motor Method that was 38% of BG. The explosion energy and detonation temperature was calculated theoretically.The characteristic explosive properties of the above compositions, example 1,2, & 3 is given below: Sr. No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Properties Density Cap sensitivity Diameter Continuity of detonation Velocity of detonation (i) 25mm (ii) 20mm (iii) 17 mm Explosion energy Explosion temperature Impact sensitivity with 10 kg. fall hammer Strength Stability test Observation 1.05 to 1.10 No. 6 detonator 25mm, 20mm, 17mm blow molded tube Passed 2700 to 3300 m/sec. 3000 -3300 m/s 2750 - 2900 m/s 2680-2800 m/s 1540-1670 kJ/Kg 1800 to 2000 Kelvin 30 kg. m no detonation 38 to 42 % BG Tested upto more than six month of storage life The main advantages of the explosive composition of the present invention are: 1. It is a cap sensitive composition in different diameter i.e. 17mm, 20mm, & 25mm. 2. The composition would be useful for perimeter blasting and tunnel projects. 3. The strength of the synergistic composition is in between 38 to 42 % of BG. 4. The shelf life of the synergistic composition is more than six months. 5. It is economically viable composition and safe in handling. We claim : 1. A composition for making slurry explosive useful for perimeter blasting in tunneling, which comprises: Oxidizing agents: (a) Ammonium nitrate 51.80 to 51.60wt% (b) Sodium nitrate 9.14 to 8.98 wt% Reducing agents: (a) Aluminium powder 2.45 to 2.34 wt% (b) Sugar 7.89 to 7.70 wt% (c) Thiourea 0.10 to 0.09 wt% (d) Urea 2.45 to 2.40 wt% (e) Guar gum 1.06 to 1.01 wt% Coolant (s)/Energy depressant : (a) Water 15.10 to 15.00 wt% (b) Sodium chloride 10.52 to 10.20 wt% Cross-linking agent(s): 0.05 to 0.04 wt% Gassing agent(s): 0.05 to 0.04 wt% 2. A composition as claimed in claiml, wherein the oxidizing agent used is ammonium nitrate, sodium nitrate or mixture thereof. 3. A composition as claimed in claims 1-2, wherein the reducing agent used is aluminium powder (flake), sugar, thiourea, urea, guar gum, or mixture thereof. 4. A composition as claimed in claims 1-3, wherein the Coolant (s)/Energy depressant used is sodium chloride, water or mixture thereof. 5. A composition as claimed in claims 1-4, wherein the cross-linking agent used is potassium pyro-antimonate, potassium dichromate or mixture thereof. 6. A composition as claimed in claims 1-5, wherein the gassing agent used is sodium nitrite, potassium thiocyanate or mixture thereof. 7. A composition as claimed in claims 1-6, wherein the oxidizing and the reducing agents used are of 99% purity. 8. A composition as claimed in claims 1-7, wherein the cross-linking agents used are of 99%purity. 9. A composition as claimed in claims 1-8, wherein the gassing agents used are of 99% purity. 10. A process for preparing slurry explosive from the composition as claimed in claim 1, which comprises, dissolving oxidizing agents in water at 70-75°C and maintaining pH of solution in the range of 4.4 to 5.0 by adding acid/base, adding to the oxidizing solution so obtained reducing agents such as thiourea, urea, sugar, guar gum and coolants/energy depressant such as sodium chloride, water to obtain a zero oxygen balanced composition in slurry form, sensitizing the said slurry by using flake grade aluminium powder followed by treatment with cross-linking and gassing agents by conventional methods as herein described to obtain slurry explosive. 11. A process as claimed in claim 10, wherein the acid/base used to maintain the pH of the oxidizing solution is such as nitric acid/sodium bicarbonate. 12. A process as claimed in claims 10-11, wherein the reducing agents(s) are added to the oxidizing solution at a temperature of 55-56°C. 13. A process as claimed in claims 10-12, wherein the slurry is sensitized by adding flake grade aluminium powder at a temperature of around 45°C. 14. A composition for making slurry explosive useful for perimeter blasting in tunneling substantially as herein described with reference to the examples.

Documents:

287-DEL-2002-Abstract-(02-04-2009).pdf

287-del-2002-abstract.pdf

287-DEL-2002-Claims-(02-04-2009).pdf

287-DEL-2002-Claims-(02-06-2009).pdf

287-del-2002-claims.pdf

287-DEL-2002-Correspondence-Others-(02-04-2009).pdf

287-DEL-2002-Correspondence-Others-(02-06-2009).pdf

287-del-2002-correspondence-others.pdf

287-DEL-2002-Description (Complete)-(02-04-2009).pdf

287-DEL-2002-Description (Complete)-(02-06-2009).pdf

287-del-2002-description (complete).pdf

287-DEL-2002-Form-1-(02-04-2009).pdf

287-DEL-2002-Form-1-(02-06-2009).pdf

287-del-2002-form-1.pdf

287-DEL-2002-Form-18-(02-04-2009).pdf

287-del-2002-form-18.pdf

287-DEL-2002-Form-2-(02-04-2009).pdf

287-del-2002-form-2.pdf

287-DEL-2002-Form-3-(02-04-2009).pdf

287-del-2002-form-3.pdf