Title of Invention	A PROCESS FOR THE RECOVERY OF FINEST CLEANS FROM COAL SLURRY AND AN EQUIPMENT THEREFOR
Abstract	A process for the recovery of finest cleans from coal slurry by conditioning slurry of fine coal particles of size below -.5 mm by treating with frothers in a ratio of 1:10 and hydrocarbon reagents in a ratio of 1.25 to 1.5 under stirring for 8 hours, at a temperature of 25 to 30°C passing the conditioned slurry through a plurality of flotation cells, removing the tailings by known methods, subjecting the resultant slurry to vacuum filtration to obtain filter cake containing finest cleans.

Title of Invention

A PROCESS FOR THE RECOVERY OF FINEST CLEANS FROM COAL SLURRY AND AN EQUIPMENT THEREFOR

Abstract

A process for the recovery of finest cleans from coal slurry by conditioning slurry of fine coal particles of size below -.5 mm by treating with frothers in a ratio of 1:10 and hydrocarbon reagents in a ratio of 1.25 to 1.5 under stirring for 8 hours, at a temperature of 25 to 30°C passing the conditioned slurry through a plurality of flotation cells, removing the tailings by known methods, subjecting the resultant slurry to vacuum filtration to obtain filter cake containing finest cleans.

Full Text	The present invention relates to a process for the recovery of finest cleans from coal slurry and an equipment therefor. The presently adopted beneficiation and recovery systems in existing coal washeries produces a large quantity of coal slurry that gets settled in nearby areas, causing pollution problems. Due to high ash content, it cannot be admixed with clean coal. This forces the coal companies dispose them to local contractors for mere domestic coke making, brick making and other non-matallurgical purposes. The present device could recover finest cleans (having low ash) which could improve the quality and value of coke made in blend with inferior raw coal, having very high ash, in suitable proportion. It opens up the possibility of producing good metallurgical coke in admixture with low ash washed coals. Application of coal quality up-gradation technologies in India started during nineteen forties and continued to grow with more and more washing plants coming up mainly for the steel sector. Indian coal is predominantly having higher ash. Increased use of high ash coal in these washeries is producing fine slurries ( feed coal input. An estimated quantity of the total fines generated can be as high as 4.75 million tonnes per annum provided the washeries operate under full designed capacity. In the existing washeries the fines below 0.5 mm are usually separated by the process known as screening on wedge wire screens. As the solid contents of the underflow remains less than 5% due to inadequate water content or adjustment, the total slurry volume becomes enormous and could be as high as 25,000 cubic meters per hour. Due to depletion of good quality raw coking coal and enforcement of more penal measures by the users for the quality of washed coal despach, the washeries are operated presently at an average capacity utilisation of 55 to 65%. Assuming 60% capacity utilisation, the total volume of slurry produced amounts to 15,000 cubic meters per hour which itself is very high and requires special attention for appropriate treatment in order to recover scarce coking coal demand of the country. In spite of the best efforts initiated by the planners over the past two decades, a large quantity of fines is locked in disposal sites. Further, due to high ash content ( more than 25%), such fines cannot be admixed with clean coal and are sold for domestic coke making, brick making and other non-metallurgical uses. The main object of the present invention is to provide a process for the recovery of finest cleans from coal slurry at coal beneficjatjon plants which obviates the drawbacks as detailed above. Another object of the present invention is to provide an equipment for the recovery of finest cleans from coal slurry. In the process & equipment flow diagram depicted in fig. 1 of the drawing accompanying this specification, raw slurry fed through the feed belt (1) to a conditioning tank (2) wherein the slurry is conditioned with hydrocarbon reagents from reagent tank (3) in admixture with water by continuous agitation. The conditioned slurry is then fed to a battery of flotation cells (4) for the separation of finest coaly matter as concentrate and removal of non-coaly matter as tailings (8). From the battery of cells the concentrate passes through a vacuum filter (5) to generate the final product filter cake (7) and the tailings flows to the settling ponds. The filtrate is received in filtrate receiver (6). The whole operation is monitored through the process controller (9). Accordingly, the present invention provides a process for the recovery of finest cleans from coal slurry which comprises conditioning slurry of fine coal particles of size below -.5 mm by treating with frothers in a ratio of 1:10 and hydrocarbon reagents in a ratio of 1.25 to 1.5 under stirring for 8 hours, at a temperature of 25 to 30°C passing the conditioned slurry through a plurality of flotation cells, removing the tailings by known methods, subjecting the resultant slurry to vacuum filtration to obtain filter cake containing finest cleans. In an embodiment of the present invention the hydrocarbon reagents used may be kerosene, diesel oil, coal tar fractions. In another embodiment of he present invention the frothers used may be pine oil, kabakol, cresylic acid. Accordingly the present invention provides an equipment for the process of the invention which comprises raw slurry delivery system(l) capable of providing controlled raw slurry feed to a conditioning tank(2), the conditioning tank being provided with a controlled reagent feed tank(3), the output of the said conditioning tank being connected by means such as control valves to the first cell of a series of flotation cells, the output of the last flotation cell being connected to the input of a vacuum filter, the said delivery system(l), conditioning tank(2), feed reagent tank(3), flotation cells(4) and vacuum filter(5) being connected to a known process controller(9). In an embodiment of the present invention the raw slurry delivery system used may be such as conveyer belt system. Raw slurry , additives (diesel and kabakol) & water mixes up by continuous stirring through impeller producing conditioned slurry as flotation cell feed. The conditioned slurry fed to the first flotation cell where froth is generated by continuous agitation through impeller of 1500 rotations per minute. Air passes through the froth to generate bubbles. Lighter coaly matter comes out and attached to the bubble surface which then separates out by automatic scrapper. The heavier muddy particles goes downwards to the cell called tailings, which passes to the next cell as feed. The next cell again produces two products same way as before. Finally from the last cell, the ultimate heavier muddy portion of the slurry comes out as tailings and passes to the tailings pond. Lighter coaly matter from the flotation cells conies out as concentrate and passes through the launder to the vacuum filter to produce final product as filter cake. The flotation receiver receives the filter wash and filtrate water and passes it to the conditioner again. Thus the whole system acts as a close water circuit with no spillage of water and thereby not creating any environmental pollution. The novel features of the present invention, overcoming the drawbacks of the prior art, are: 1. The device recovers the finest cleans( having low ash) from accumulated coal slurry at coal beneficiation plants( having very high ash) which is otherwise a waste material obtained from coal beneficiation plants. 2. The recovered cleans have high vitrinite content. It opens up the possibility of producing good metallurgical coke in admixture with low ash washed coals. 3. The device works under complete closed water circuit system. This prevents severe environmental pollution in the vicinity of the working site. The following examples are given by way of illustration of the present invention and should not be construed to the limit the scope of the present invention. Example-1 Raw slurry ( The total input slurry for the run was 320 kg having 25% ash and 25% moisture whereas the cleans obtained were 160 kg having 15% ash and 20% moisture. The tailings obtained were 160 kg. Example-2 Raw slurry ( The total input slurry for the run was 3200 kg having 30% ash and 25% moisture whereas the cleans obtained were 1600 kg having 15% ash and 20% moisture. The tailings obtained were 1600 kg. The main advantages of the present invention are : 1. The coal slurry/fines which is otherwise utilised for mere domestic coke making, brick making , other non-metallurgical purposes etc; could augment the supply of scarce coking coal to the steel industry. 2. The device works under complete closed water circuit system. This prevents environmental pollution in the vicinity of the working sites. 3. There exists pulp level control in each flotation cell. We claim : 1. A process for the recovery of finest cleans from coal slurry which comprises conditioning slurry of fine coal particles of size below -.5 mm by treating with frothers in a ratio of 1:10 and hydrocarbon reagents in a ratio of 1.25 to 1.5 under stirring for 8 hours, at a temperature of 25 to 30°C passing the conditioned slurry through a plurality of flotation cells, removing the tailings by known methods, subjecting the resultant slurry to vacuum filtration to obtain filter cake containing finest cleans. 2. A process as claimed in claim 1 wherein the hydrocarbon reagents used is kerosene, diesel oil, coal tar fractions. 3. A process as claimed in claims 1-2 wherein the frothers used is pine oil, kabakol, cresylic acid. 4. A device for recovery of finest cleans from coal slurry wherein the recovery of finest cleans from coal slurry by a process as claimed in claim 1 to 3 wherein raw slurry delivery system (1) capable of providing controlled raw slurry feed to a conditioning tank (2), the conditioning tank being provided with a controlled reagent feed tank (3), the output of the said conditioning tank being connected by means such as control valves to the first cell of a series of flotation cells, the output of the last flotation cell being connected to the input of a vacuum filter, the said delivery system (1), conditioning tank (2), feed reagent tank (3), flotation cells (4) and vacuum filter (5) being connected to a known process controller (9). 5. A device as claimed in claim 4 wherein the raw slurry delivery system used is such as conveyor belt system. 6. A process for the recovery of finest cleans from coal slurry substantially as herein described and illustrated with reference to the examples.

Full Text

The present invention relates to a process for the recovery of finest cleans from coal slurry and an equipment therefor.
The presently adopted beneficiation and recovery systems in existing coal washeries produces a large quantity of coal slurry that gets settled in nearby areas, causing pollution problems. Due to high ash content, it cannot be admixed with clean coal. This forces the coal companies dispose them to local contractors for mere domestic coke making, brick making and other non-matallurgical purposes. The present device could recover finest cleans (having low ash) which could improve the quality and value of coke made in blend with inferior raw coal, having very high ash, in suitable proportion. It opens up the possibility of producing good metallurgical coke in admixture with low ash washed coals.
Application of coal quality up-gradation technologies in India started during nineteen forties and continued to grow with more and more washing plants coming up mainly for the steel sector. Indian coal is predominantly having higher ash. Increased use of high ash coal in these washeries is producing fine slurries (
feed coal input. An estimated quantity of the total fines generated can be as high as 4.75 million tonnes per annum provided the washeries operate under full designed capacity. In the existing washeries the fines below 0.5 mm are usually separated by the process known as screening on wedge wire screens. As the solid contents of the underflow remains less than 5% due to inadequate water content or adjustment, the total slurry volume becomes enormous and could be as high as 25,000 cubic meters per hour. Due to depletion of good quality raw coking coal and enforcement of more penal measures by the users for the quality of washed coal despach, the washeries are operated presently at an average capacity utilisation of 55 to 65%. Assuming 60% capacity utilisation, the total volume of slurry produced amounts to 15,000 cubic meters per hour which itself is very high and requires special attention for appropriate treatment in order to recover scarce coking coal demand of the country. In spite of the best efforts initiated by the planners over the past two decades, a large quantity of fines is locked in disposal sites. Further, due to high ash content ( more than 25%), such fines cannot be admixed with clean coal and are sold for domestic coke making, brick making and other non-metallurgical uses.
The main object of the present invention is to provide a process for the recovery of finest cleans from coal slurry at coal beneficjatjon plants which obviates the drawbacks as detailed above.
Another object of the present invention is to provide an equipment for the recovery of finest cleans from coal slurry.

In the process & equipment flow diagram depicted in fig. 1 of the drawing accompanying this specification, raw slurry fed through the feed belt (1) to a conditioning tank (2) wherein the slurry is conditioned with hydrocarbon reagents from reagent tank (3) in admixture with water by continuous agitation. The conditioned slurry is then fed to a battery of flotation cells (4) for the separation of finest coaly matter as concentrate and removal of non-coaly matter as tailings (8). From the battery of cells the concentrate passes through a vacuum filter (5) to generate the final product filter cake (7) and the tailings flows to the settling ponds. The filtrate is received in filtrate receiver (6). The whole operation is monitored through the process controller (9).
Accordingly, the present invention provides a process for the recovery of finest cleans from coal slurry which comprises conditioning slurry of fine coal particles of size below -.5 mm by treating with frothers in a ratio of 1:10 and hydrocarbon reagents in a ratio of 1.25 to 1.5 under stirring for 8 hours, at a temperature of 25 to 30°C passing the conditioned slurry through a plurality of flotation cells, removing the tailings by known methods, subjecting the resultant slurry to vacuum filtration to obtain filter cake containing finest cleans.
In an embodiment of the present invention the hydrocarbon reagents used may be kerosene, diesel oil, coal tar fractions.
In another embodiment of he present invention the frothers used may be pine oil, kabakol, cresylic acid.

Accordingly the present invention provides an equipment for the process of the invention which comprises raw slurry delivery system(l) capable of providing controlled raw slurry feed to a conditioning tank(2), the conditioning tank being provided with a controlled reagent feed tank(3), the output of the said conditioning tank being connected by means such as control valves to the first cell of a series of flotation cells, the output of the last flotation cell being connected to the input of a vacuum filter, the said delivery system(l), conditioning tank(2), feed reagent tank(3), flotation cells(4) and vacuum filter(5) being connected to a known process controller(9).
In an embodiment of the present invention the raw slurry delivery system used may be such as conveyer belt system.
Raw slurry , additives (diesel and kabakol) & water mixes up by continuous stirring through impeller producing conditioned slurry as flotation cell feed. The conditioned slurry fed to the first flotation cell where froth is generated by continuous agitation through impeller of 1500 rotations per minute. Air passes through the froth to generate bubbles. Lighter coaly matter comes out and attached to the bubble surface which then separates out by automatic scrapper. The heavier muddy particles goes downwards to the cell called tailings, which passes to the next cell as feed. The next cell again produces two products same way as before. Finally from the last cell, the ultimate heavier muddy portion of the slurry comes out as tailings and passes to the tailings pond.

Lighter coaly matter from the flotation cells conies out as concentrate and passes through the launder to the vacuum filter to produce final product as filter cake.
The flotation receiver receives the filter wash and filtrate water and passes it to the conditioner again. Thus the whole system acts as a close water circuit with no spillage of water and thereby not creating any environmental pollution.
The novel features of the present invention, overcoming the drawbacks of the prior art, are:
1. The device recovers the finest cleans( having low ash) from accumulated coal
slurry at coal beneficiation plants( having very high ash) which is otherwise a
waste material obtained from coal beneficiation plants.
2. The recovered cleans have high vitrinite content. It opens up the possibility of
producing good metallurgical coke in admixture with low ash washed coals.
3. The device works under complete closed water circuit system. This prevents
severe environmental pollution in the vicinity of the working site.
The following examples are given by way of illustration of the present invention and should not be construed to the limit the scope of the present invention.
Example-1
Raw slurry ( The total input slurry for the run was 320 kg having 25% ash and 25% moisture whereas the cleans obtained were 160 kg having 15% ash and 20% moisture. The tailings obtained were 160 kg.
Example-2
Raw slurry ( The total input slurry for the run was 3200 kg having 30% ash and 25% moisture whereas the cleans obtained were 1600 kg having 15% ash and 20% moisture. The tailings obtained were 1600 kg.
The main advantages of the present invention are :
1. The coal slurry/fines which is otherwise utilised for mere domestic coke making,
brick making , other non-metallurgical purposes etc; could augment the supply
of scarce coking coal to the steel industry.
2. The device works under complete closed water circuit system. This prevents
environmental pollution in the vicinity of the working sites.
3. There exists pulp level control in each flotation cell.

We claim :
1. A process for the recovery of finest cleans from coal slurry which comprises
conditioning slurry of fine coal particles of size below -.5 mm by treating with
frothers in a ratio of 1:10 and hydrocarbon reagents in a ratio of 1.25 to 1.5
under stirring for 8 hours, at a temperature of 25 to 30°C passing the
conditioned slurry through a plurality of flotation cells, removing the tailings
by known methods, subjecting the resultant slurry to vacuum filtration to
obtain filter cake containing finest cleans.
2. A process as claimed in claim 1 wherein the hydrocarbon reagents used is
kerosene, diesel oil, coal tar fractions.
3. A process as claimed in claims 1-2 wherein the frothers used is pine oil,
kabakol, cresylic acid.
4. A device for recovery of finest cleans from coal slurry wherein the recovery
of finest cleans from coal slurry by a process as claimed in claim 1 to 3
wherein raw slurry delivery system (1) capable of providing controlled raw

slurry feed to a conditioning tank (2), the conditioning tank being provided
with a controlled reagent feed tank (3), the output of the said conditioning tank being connected by means such as control valves to the first cell of a series of flotation cells, the output of the last flotation cell being connected to the input of a vacuum filter, the said delivery system (1), conditioning tank (2), feed reagent tank (3), flotation cells (4) and vacuum filter (5) being connected to a known process controller (9).

5. A device as claimed in claim 4 wherein the raw slurry delivery system used
is such as conveyor belt system.
6. A process for the recovery of finest cleans from coal slurry substantially as
herein described and illustrated with reference to the examples.

Documents:

205-del-2001-abstract.pdf

205-del-2001-claims.pdf

205-del-2001-correspondence-others.pdf

205-del-2001-correspondence-po.pdf

205-del-2001-description (complete).pdf

205-del-2001-drawings.pdf

205-del-2001-form-1.pdf

205-del-2001-form-19.pdf

205-del-2001-form-2.pdf

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Patent Number

230363

Indian Patent Application Number

205/DEL/2001

PG Journal Number

11/2009

Publication Date

13-Mar-2009

Grant Date

26-Feb-2009

Date of Filing

27-Feb-2001

Name of Patentee

See attached documents

Applicant Address

See attached documents

Inventors:

#	Inventor's Name	Inventor's Address
1	See attached documents	See attached documents

PCT International Classification Number

E21C 41/18

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA