CA2020035A1 - Method for processing coal - Google Patents
Method for processing coalInfo
- Publication number
- CA2020035A1 CA2020035A1 CA 2020035 CA2020035A CA2020035A1 CA 2020035 A1 CA2020035 A1 CA 2020035A1 CA 2020035 CA2020035 CA 2020035 CA 2020035 A CA2020035 A CA 2020035A CA 2020035 A1 CA2020035 A1 CA 2020035A1
- Authority
- CA
- Canada
- Prior art keywords
- coal
- ash
- fine
- ultra
- mesh
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000003245 coal Substances 0.000 title claims abstract description 81
- 238000000034 method Methods 0.000 title claims abstract description 43
- 238000012545 processing Methods 0.000 title claims description 9
- 238000001035 drying Methods 0.000 claims abstract description 11
- 238000005188 flotation Methods 0.000 claims abstract description 11
- 239000012530 fluid Substances 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 6
- 239000002002 slurry Substances 0.000 claims description 5
- 238000002485 combustion reaction Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 239000011882 ultra-fine particle Substances 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 239000013618 particulate matter Substances 0.000 claims 6
- 239000010419 fine particle Substances 0.000 claims 1
- 239000000203 mixture Substances 0.000 claims 1
- 239000002699 waste material Substances 0.000 abstract description 5
- 238000011084 recovery Methods 0.000 abstract description 4
- 238000005406 washing Methods 0.000 abstract description 4
- 238000005065 mining Methods 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 6
- 238000000926 separation method Methods 0.000 description 5
- 230000032258 transport Effects 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 description 2
- 238000001914 filtration Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- BGRJTUBHPOOWDU-UHFFFAOYSA-N sulpiride Chemical compound CCN1CCCC1CNC(=O)C1=CC(S(N)(=O)=O)=CC=C1OC BGRJTUBHPOOWDU-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Combined Means For Separation Of Solids (AREA)
Abstract
ABSTRACT
A process for recovery of combustionable coal from fine coal such as frequently considered waste coal from mining operations includes drying and classifying the raw coal into ultra-fine and fine size classes. The ultra-fine size class is directed to a collector and further separated in a strictly dry manner while the fine size class is separated in a flotation apparatus to divide out the coal and ash therein which are subsequently screened, with or without washing and drying at that time. The screened fine size coal, after being dried, is collected in a stock pile, as is also any dry ultra-fine size coal as discharged by the collector.
A process for recovery of combustionable coal from fine coal such as frequently considered waste coal from mining operations includes drying and classifying the raw coal into ultra-fine and fine size classes. The ultra-fine size class is directed to a collector and further separated in a strictly dry manner while the fine size class is separated in a flotation apparatus to divide out the coal and ash therein which are subsequently screened, with or without washing and drying at that time. The screened fine size coal, after being dried, is collected in a stock pile, as is also any dry ultra-fine size coal as discharged by the collector.
Description
METHOD FOR PROCESSI~G FI~E COAL
FIELD OF THE INVENTION
This invsntion relates gsnerally to the wash;ng of coal and in particular, to an ;mproved method of separating ultra-fine grades of coa1 including the separation of these fine grades from ash included therewith.
BACKGROUND OF THE INVENTION
There exists in the coal industry, an increasing need for a process to clean and wash fine coal. This fine coal can be defined as particulate coal ranging is size from O to 1~4 inch and may be further classified into two categories; namely classified fine coal (28 mesh to 1\4 inch), and classified ultra-fine coal (0 to 28 mesh). Coal particles w;th;n the fine range are being produced in larger and larger quantities due to the ;ncreased use of continuous mining operations. In addition, current economic trends in the energy market make it more feasible to reprocess the waste piles from previous coal processing operations to recover the fine coal particles that have been discarded and until the present ;nvent;on, have not ¦
been economically recoverable.
Raw coal may be processed by a number of methods which may ;nclude: crushing, jig wash;ng, dense media washing, s;ft;ng, flotation, centr;fug;ng, magnet;c separation and drying. The first of these processes, crushing, leaves the coal in an assortment o~ particles and lumps which may range from microscop;c to several ;nches in size. At th;s po;nt in the process the raw coal still contains a large percentage of unde rable matter commonly referred to ~5 ssh. This ar,h must be .
~020035 separated from the coal as efficiently as possible to obtain a pure coal product suitable for combustion. The aforementioned washing, sifting, flotation, centrifuging, and drying are techniques used to separate the coal from the ash and to prepare the coal for combustion. These separation techniques can be div;ded into two categories, wet processes and dry processes.
Dry processes generally include dry cyclones, sifting, and shaker tables such as the vibratory screen as disclosed in U.S.
Patent No. 3,113,098 issued December 3, 1963 to Ffoulkes. U.S.
Patent No. 3,901,794 ;ssued Au~ust 26, 1975 to Hemme et al.
discloses an e~ample of a circulatory air sifter of the type that may be employed in dry coal processin~ or similar operations.
Wet processes ~enerally include jig washing, dense media flotation and cyclones. Most wet processes also include various recovery and filtering systems in order to efficiently recycle the fluid used in the process.
The large majority of current coal processing plants use a wet process to clean the coal. Ultra-fine particles that enter into the wet processes cause inherent problems in subsequent handling of ~he fluids used in these wet processes. The fluid circuits in such processes become unwieldy and costly. One such example can be found in U.S. Patent No. 4,217,207 dated August 12, 1980 and issued to Liller. Thus, there does not exist ;n the art, an efficlent method to eliminate the ultra fine particles in a wet process.
Past coal processing plants have discarded a large amount of fine coal particles along with the separated ash and debris.
Current econom;c trends in the energy market dictate that a feasible process is needed to reprocess fine coal from waste piles of previous coal operations in order to recover the fine coa~ which is Dresent therein.
SUMMARY OF THE INVENTION
By the pressnt invention, a method for processing fine coal is provided in which the raw coal feed is first dried and classified into two size categories, fines (28 mesh and larger) and ultra-fines (less than 28 mesh). The drying and classifying is followed by separate cleaning processes for the fines and the ultra-fines. ~he fines are cleaned using a wet process with a flotation tank and subsequent drying while the ultra-f;nes are cleaned using a dry cyclone.
Accordingly it is one of the objects of the present invention to provide a method of classifying and cleaning fine coal, which eliminates the ultra fines from any wet processes.
It i8 a further object of this invention to provide a method whlch will make it possible more efficiently to recover the f1nes from the waste piles of previous coal processing operations.
Yet another object of this invention is to provide a method for processing coal which results in a relatively dry and easy to handle waste product.
With these and other objects in view which will more readily appear as the nature of the invention ;s better understood, the invention consists in the novel combination and arrangement of¦
parts hereinafter more fully described, i1lustrated and claimed with reference being made to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram illustrattn~ the sequence of stages employHd in the preferred method of the present invention.
F;g. 2 i3 a block diagram of an alternate embodiment of tha present method.
~1 202003~ 1 DESCRIPTION OF T~E PREFERRED EMBODIMENT
Referring now to the drawings, particularly Fig. 1, a raw coal feed consisting of various sizes of particulate coal and ash and generally ranging in sizes of from O to 3\4 inches, but it will be understood not to be limited to these sizes, is fed into a dryer/classifier 3. The raw coal is fed into dryer/classifier 3 by means of an input transporter or regulated feed mechanism 2 such as a vibrating feeder, screw feeder, belt conveyer, or other means as are well known in the art and need not be specifically illustrated hersin. The dryer/classifier 3 according to a preferred embodiment of the present invention is of the fluid-ized-bed type and ;s provided with heat from an outside heating source 4 wh;ch supplies the heat for all drytng needs w;thin the process of thi~ invent;on. The dryer/classifier 3 dries the raw coal feed to reduce the moisture content therein and classifies the coal feed into two size categories with the breaking point between the categories be;ng at about 28 mesh. The two size categories of the raw coal feed include a smaller size class of coal, hereafter referred to as "ultra-f1ne" coal comprising partlculate matter substantially 28 mesh and smaller and a larger size class of coal comprising particular matter substantially 28 mesh and larger, hereafter referred to as "fine" coal.
The ultra-fines which have been separated from the fines by the classif;er 4 are diverted and transported to a dry cyclone separator 19 through a duct 5 by such means as may be determined most practical by the individual user of this invention. The cyclone apparatus 19 separates the ultra-fines from the fluidiz-ing air stream and has a selective output to enable the user to collect the uttra-fines in a bag type collector or to mix the ultra-fine coal and any other products separated by the device 19 202003~
w;th one of the output streams from the classified fines cleaning process as described hereinafter. In any case, the air, by which the collector 19 is opera~ed, will be understood to be discharged through a conduit 23 directed to a suitable bag, or other type air cleaner 24, insuring that acceptable clean atr is released to the atmosphere as at 25.
The fines from the dryer/classifier 3 are transported by a suttable convsyer 6 to a heavy media separator 7, wherein the coal fines are contacted with a fluid media. The separator 7 will be understood to be of the flotation type wherein the fluid media used will be of a specific gravity that will allow the ash and other undesirable particles to sink and allow the coal to float. The wet ash, which has settled to the bottom, then flows, as a slurry, from a bottom discharge through a trough 9 to an ash screen conveyer 11 of the type retaining and transporting the delivered ash while allowing excess fluid media to pass there-through and be collected for re-cycl;ng through the separator 7.
The lower density coal in the flotatlon separator 7 float~
over a weir (not shown) therein and is discharged, likewise as a slurry, to a trough 10 leading to a conveyer 12. The two conveyers 11 and 12 are of the vibrating type and each employs a fine bar (close opening) screen~ As in the case of conveying screen 11, the collected fluid media from the screen mechanism 12 is re-cycled to the separator 7. These screens 11,12 perform the function of conveying the ash or coal respectively, while draining the excess fluid media resulting from the flotation procedure.
The screened products in each of the units 11 and 12 may be washed and dried before leav~ng the conveying screens. Well known water sprayers (not shown) may be employed, together with heat from the same unitary source as providing the heat 4.
2020~33 Following the above screening, the ash is then transported by any suitable conveying means 17 to a refuse stock pile 27 for disposal. The classified fine coa1 from the screenin~ mechanism 12 is transported by a chute or conveyer belt 14 to a dryer 16 which is supplied with heat 15 from the same external heat source wh;ch supplies the heat 4 for the dryer/classifier 3 used at the start of the process. The clean, dry classified fine coal output of the final dryer 16 i 8 transported by appropriate conveyer means 18 to a stock pile 28 of dry, clean coal, suitable for combustion.
As previously mentioned, the collector apparatus 19 provides a plurality of selective and proportional outputs. As shown in F1g. 1, the collected or separated ultra-fines may be totally or parttally d;rected, by way of appropriate conveyer means 22, to an ultra-fines stock pile 26. Alternately the ultra-fines may be totally or partially directed, by a conveyor 21 to the conveyor 17 lead;ng to the damp ash refuse stock pile 27, or similarly, by conveyor 20, to the conveyor 18 leadin~ to the dry clean coal stock pile 2~. Mix;ng the ultra-f;nes with the dry clean coal enables the user of this process to adjust the BTU content of the f;nal product to account for the buyers' needs. In the foregoin~
manner, it will be appreciated that an improved process is pro-vided wherein maximum recovery of all usable components of the raw coal feed ;s achieved. According to this preferred embodi-ment, it ;s recommended that a portion of the ultra-fines which are output from the cyclone 19 be used for heat ~eneration in an outside heat scurce to supply heat 4 and t5 for the dryer classi-f;er 3 and dryer t6. The process is not to be limited to the use of the ultra-fines for heat ~eneration but may include the use of other commerc;ally ava;lable fuels as may be dictated by ;nd;vid-2020~3~
ual applications.
An alternative embodiment of the present invention is illus-trated in the block diagram of Fig. 2, wherein coal fines from the aforementioned dryer/classifier are transported by conveyor 6' to separator 7' for further processing. The ash which set-tles to the bottom of the heavy media flotation separator 7' flows through a trough 9' to a conveyer 30, while the f;ne coal floating in the flotation tank passes over a weir therein and through a trough 10' which transports the coal to the screen conveyer 30. Conveyer 30 likewise is a vibrating screen type conveyer with a fine bar (close opening) screen which enables the recovery and re-cycling of remaining media from the media separa-tion process. The conveyer 30,30'is a common conveyer with a long;tud;nally d;sposed divider 30' such that the screen simulta-neously transfers in a parallel manner, both the coal and ash products which are then directed, by means of transport;ng means 31 and 32 to a common dryer 16', l;kewise having dividing means 16" to maintain separation of the coal and ash during the drying process. The dryer is supplied with heat from the same heat source used for the ;n;tial dryer/class;fiér operation at the start of the process. A term;nal conveyer 33 removes the dry ash from the dryer 16' and transports it to a refuse stock pile 34 for d;sposal. A second terminal conveyer 35 transports the clean dry coal to a stock pile 36 for the final product to be used for combust;on.
It is to be understood that the present invent1on 1s not limited to the embodiments described above, but encompasses any and all modifications within the scope of the claims appended hereto.
FIELD OF THE INVENTION
This invsntion relates gsnerally to the wash;ng of coal and in particular, to an ;mproved method of separating ultra-fine grades of coa1 including the separation of these fine grades from ash included therewith.
BACKGROUND OF THE INVENTION
There exists in the coal industry, an increasing need for a process to clean and wash fine coal. This fine coal can be defined as particulate coal ranging is size from O to 1~4 inch and may be further classified into two categories; namely classified fine coal (28 mesh to 1\4 inch), and classified ultra-fine coal (0 to 28 mesh). Coal particles w;th;n the fine range are being produced in larger and larger quantities due to the ;ncreased use of continuous mining operations. In addition, current economic trends in the energy market make it more feasible to reprocess the waste piles from previous coal processing operations to recover the fine coal particles that have been discarded and until the present ;nvent;on, have not ¦
been economically recoverable.
Raw coal may be processed by a number of methods which may ;nclude: crushing, jig wash;ng, dense media washing, s;ft;ng, flotation, centr;fug;ng, magnet;c separation and drying. The first of these processes, crushing, leaves the coal in an assortment o~ particles and lumps which may range from microscop;c to several ;nches in size. At th;s po;nt in the process the raw coal still contains a large percentage of unde rable matter commonly referred to ~5 ssh. This ar,h must be .
~020035 separated from the coal as efficiently as possible to obtain a pure coal product suitable for combustion. The aforementioned washing, sifting, flotation, centrifuging, and drying are techniques used to separate the coal from the ash and to prepare the coal for combustion. These separation techniques can be div;ded into two categories, wet processes and dry processes.
Dry processes generally include dry cyclones, sifting, and shaker tables such as the vibratory screen as disclosed in U.S.
Patent No. 3,113,098 issued December 3, 1963 to Ffoulkes. U.S.
Patent No. 3,901,794 ;ssued Au~ust 26, 1975 to Hemme et al.
discloses an e~ample of a circulatory air sifter of the type that may be employed in dry coal processin~ or similar operations.
Wet processes ~enerally include jig washing, dense media flotation and cyclones. Most wet processes also include various recovery and filtering systems in order to efficiently recycle the fluid used in the process.
The large majority of current coal processing plants use a wet process to clean the coal. Ultra-fine particles that enter into the wet processes cause inherent problems in subsequent handling of ~he fluids used in these wet processes. The fluid circuits in such processes become unwieldy and costly. One such example can be found in U.S. Patent No. 4,217,207 dated August 12, 1980 and issued to Liller. Thus, there does not exist ;n the art, an efficlent method to eliminate the ultra fine particles in a wet process.
Past coal processing plants have discarded a large amount of fine coal particles along with the separated ash and debris.
Current econom;c trends in the energy market dictate that a feasible process is needed to reprocess fine coal from waste piles of previous coal operations in order to recover the fine coa~ which is Dresent therein.
SUMMARY OF THE INVENTION
By the pressnt invention, a method for processing fine coal is provided in which the raw coal feed is first dried and classified into two size categories, fines (28 mesh and larger) and ultra-fines (less than 28 mesh). The drying and classifying is followed by separate cleaning processes for the fines and the ultra-fines. ~he fines are cleaned using a wet process with a flotation tank and subsequent drying while the ultra-f;nes are cleaned using a dry cyclone.
Accordingly it is one of the objects of the present invention to provide a method of classifying and cleaning fine coal, which eliminates the ultra fines from any wet processes.
It i8 a further object of this invention to provide a method whlch will make it possible more efficiently to recover the f1nes from the waste piles of previous coal processing operations.
Yet another object of this invention is to provide a method for processing coal which results in a relatively dry and easy to handle waste product.
With these and other objects in view which will more readily appear as the nature of the invention ;s better understood, the invention consists in the novel combination and arrangement of¦
parts hereinafter more fully described, i1lustrated and claimed with reference being made to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram illustrattn~ the sequence of stages employHd in the preferred method of the present invention.
F;g. 2 i3 a block diagram of an alternate embodiment of tha present method.
~1 202003~ 1 DESCRIPTION OF T~E PREFERRED EMBODIMENT
Referring now to the drawings, particularly Fig. 1, a raw coal feed consisting of various sizes of particulate coal and ash and generally ranging in sizes of from O to 3\4 inches, but it will be understood not to be limited to these sizes, is fed into a dryer/classifier 3. The raw coal is fed into dryer/classifier 3 by means of an input transporter or regulated feed mechanism 2 such as a vibrating feeder, screw feeder, belt conveyer, or other means as are well known in the art and need not be specifically illustrated hersin. The dryer/classifier 3 according to a preferred embodiment of the present invention is of the fluid-ized-bed type and ;s provided with heat from an outside heating source 4 wh;ch supplies the heat for all drytng needs w;thin the process of thi~ invent;on. The dryer/classifier 3 dries the raw coal feed to reduce the moisture content therein and classifies the coal feed into two size categories with the breaking point between the categories be;ng at about 28 mesh. The two size categories of the raw coal feed include a smaller size class of coal, hereafter referred to as "ultra-f1ne" coal comprising partlculate matter substantially 28 mesh and smaller and a larger size class of coal comprising particular matter substantially 28 mesh and larger, hereafter referred to as "fine" coal.
The ultra-fines which have been separated from the fines by the classif;er 4 are diverted and transported to a dry cyclone separator 19 through a duct 5 by such means as may be determined most practical by the individual user of this invention. The cyclone apparatus 19 separates the ultra-fines from the fluidiz-ing air stream and has a selective output to enable the user to collect the uttra-fines in a bag type collector or to mix the ultra-fine coal and any other products separated by the device 19 202003~
w;th one of the output streams from the classified fines cleaning process as described hereinafter. In any case, the air, by which the collector 19 is opera~ed, will be understood to be discharged through a conduit 23 directed to a suitable bag, or other type air cleaner 24, insuring that acceptable clean atr is released to the atmosphere as at 25.
The fines from the dryer/classifier 3 are transported by a suttable convsyer 6 to a heavy media separator 7, wherein the coal fines are contacted with a fluid media. The separator 7 will be understood to be of the flotation type wherein the fluid media used will be of a specific gravity that will allow the ash and other undesirable particles to sink and allow the coal to float. The wet ash, which has settled to the bottom, then flows, as a slurry, from a bottom discharge through a trough 9 to an ash screen conveyer 11 of the type retaining and transporting the delivered ash while allowing excess fluid media to pass there-through and be collected for re-cycl;ng through the separator 7.
The lower density coal in the flotatlon separator 7 float~
over a weir (not shown) therein and is discharged, likewise as a slurry, to a trough 10 leading to a conveyer 12. The two conveyers 11 and 12 are of the vibrating type and each employs a fine bar (close opening) screen~ As in the case of conveying screen 11, the collected fluid media from the screen mechanism 12 is re-cycled to the separator 7. These screens 11,12 perform the function of conveying the ash or coal respectively, while draining the excess fluid media resulting from the flotation procedure.
The screened products in each of the units 11 and 12 may be washed and dried before leav~ng the conveying screens. Well known water sprayers (not shown) may be employed, together with heat from the same unitary source as providing the heat 4.
2020~33 Following the above screening, the ash is then transported by any suitable conveying means 17 to a refuse stock pile 27 for disposal. The classified fine coa1 from the screenin~ mechanism 12 is transported by a chute or conveyer belt 14 to a dryer 16 which is supplied with heat 15 from the same external heat source wh;ch supplies the heat 4 for the dryer/classifier 3 used at the start of the process. The clean, dry classified fine coal output of the final dryer 16 i 8 transported by appropriate conveyer means 18 to a stock pile 28 of dry, clean coal, suitable for combustion.
As previously mentioned, the collector apparatus 19 provides a plurality of selective and proportional outputs. As shown in F1g. 1, the collected or separated ultra-fines may be totally or parttally d;rected, by way of appropriate conveyer means 22, to an ultra-fines stock pile 26. Alternately the ultra-fines may be totally or partially directed, by a conveyor 21 to the conveyor 17 lead;ng to the damp ash refuse stock pile 27, or similarly, by conveyor 20, to the conveyor 18 leadin~ to the dry clean coal stock pile 2~. Mix;ng the ultra-f;nes with the dry clean coal enables the user of this process to adjust the BTU content of the f;nal product to account for the buyers' needs. In the foregoin~
manner, it will be appreciated that an improved process is pro-vided wherein maximum recovery of all usable components of the raw coal feed ;s achieved. According to this preferred embodi-ment, it ;s recommended that a portion of the ultra-fines which are output from the cyclone 19 be used for heat ~eneration in an outside heat scurce to supply heat 4 and t5 for the dryer classi-f;er 3 and dryer t6. The process is not to be limited to the use of the ultra-fines for heat ~eneration but may include the use of other commerc;ally ava;lable fuels as may be dictated by ;nd;vid-2020~3~
ual applications.
An alternative embodiment of the present invention is illus-trated in the block diagram of Fig. 2, wherein coal fines from the aforementioned dryer/classifier are transported by conveyor 6' to separator 7' for further processing. The ash which set-tles to the bottom of the heavy media flotation separator 7' flows through a trough 9' to a conveyer 30, while the f;ne coal floating in the flotation tank passes over a weir therein and through a trough 10' which transports the coal to the screen conveyer 30. Conveyer 30 likewise is a vibrating screen type conveyer with a fine bar (close opening) screen which enables the recovery and re-cycling of remaining media from the media separa-tion process. The conveyer 30,30'is a common conveyer with a long;tud;nally d;sposed divider 30' such that the screen simulta-neously transfers in a parallel manner, both the coal and ash products which are then directed, by means of transport;ng means 31 and 32 to a common dryer 16', l;kewise having dividing means 16" to maintain separation of the coal and ash during the drying process. The dryer is supplied with heat from the same heat source used for the ;n;tial dryer/class;fiér operation at the start of the process. A term;nal conveyer 33 removes the dry ash from the dryer 16' and transports it to a refuse stock pile 34 for d;sposal. A second terminal conveyer 35 transports the clean dry coal to a stock pile 36 for the final product to be used for combust;on.
It is to be understood that the present invent1on 1s not limited to the embodiments described above, but encompasses any and all modifications within the scope of the claims appended hereto.
Claims (6)
1. A method for processing a raw coal feed consisting of var-ious sizes of particulate coal and ash ranging in sizes of from 0 to about 3/4 inches, comprising:
drying the raw coal feed by heating means and concurrently classifying said raw coal feed into a first size class of ultra-fine particulate matter substantially 28 mesh and smaller and a second size class of fine particulate matter substantially 28 mesh and larger by air classifying means;
separating said dried and classified raw coal feed into said first size of particulate matter and collecting ultra-fine parti-cles of coal and ash of 28 mesh size and smaller contained there-in and said second size class of fine particulate matter retain-ing fine particles of coal and ash of 28 mesh and larger;
contacting said second size class of particulate matter with a fluid media in a flotation separator, wherein said fluid media has a specific gravity which allows coal contained therein to float and the ash and other components of the particulate matter are allowed to sink;
recovering said coal and ash as separate slurries;
draining excess fluid media from said separate slurries of coal and ash by means of conveyor screens and collecting said ash as refuse;
drying said coal by heating means; and collecting a dry, clean product of coal fines greater than 28 mesh suitable for combustion.
drying the raw coal feed by heating means and concurrently classifying said raw coal feed into a first size class of ultra-fine particulate matter substantially 28 mesh and smaller and a second size class of fine particulate matter substantially 28 mesh and larger by air classifying means;
separating said dried and classified raw coal feed into said first size of particulate matter and collecting ultra-fine parti-cles of coal and ash of 28 mesh size and smaller contained there-in and said second size class of fine particulate matter retain-ing fine particles of coal and ash of 28 mesh and larger;
contacting said second size class of particulate matter with a fluid media in a flotation separator, wherein said fluid media has a specific gravity which allows coal contained therein to float and the ash and other components of the particulate matter are allowed to sink;
recovering said coal and ash as separate slurries;
draining excess fluid media from said separate slurries of coal and ash by means of conveyor screens and collecting said ash as refuse;
drying said coal by heating means; and collecting a dry, clean product of coal fines greater than 28 mesh suitable for combustion.
2. The method according to claim 1 wherein said dry, clean product of coal fines consists of coal particles ranging in size of 28 mesh to 1/4 inch.
3. The method according to claim 1 wherein said excess fluid media is collected and recycled to said flotation separa-tor.
4. The method according to claim 1 wherein said slurries of coal fines and ash are washed by means of water sprayers before leaving the conveyer screens.
5. The method according to claim 4 wherein said ash after being washed is dried by heating means.
6. The method according to claim 1 wherein the ultra-fines collected and said dry, clean product of coal fines are mixed to adjust the BTU content of the resulting coal mixture.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2020035 CA2020035A1 (en) | 1990-06-28 | 1990-06-28 | Method for processing coal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2020035 CA2020035A1 (en) | 1990-06-28 | 1990-06-28 | Method for processing coal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2020035A1 true CA2020035A1 (en) | 1991-12-29 |
Family
ID=4145361
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2020035 Abandoned CA2020035A1 (en) | 1990-06-28 | 1990-06-28 | Method for processing coal |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2020035A1 (en) |
-
1990
- 1990-06-28 CA CA 2020035 patent/CA2020035A1/en not_active Abandoned
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