CA1118723A - Heavy magnetic media hydrocyclonic separation process with screening, magnetic separation and recycling of liquids - Google Patents
Heavy magnetic media hydrocyclonic separation process with screening, magnetic separation and recycling of liquidsInfo
- Publication number
- CA1118723A CA1118723A CA000311557A CA311557A CA1118723A CA 1118723 A CA1118723 A CA 1118723A CA 000311557 A CA000311557 A CA 000311557A CA 311557 A CA311557 A CA 311557A CA 1118723 A CA1118723 A CA 1118723A
- Authority
- CA
- Canada
- Prior art keywords
- particles
- heavy
- suspension
- fraction
- specifically
- 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.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/005—General arrangement of separating plant, e.g. flow sheets specially adapted for coal
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B5/00—Washing granular, powdered or lumpy materials; Wet separating
- B03B5/28—Washing granular, powdered or lumpy materials; Wet separating by sink-float separation
- B03B5/30—Washing granular, powdered or lumpy materials; Wet separating by sink-float separation using heavy liquids or suspensions
- B03B5/44—Application of particular media therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C1/00—Magnetic separation
- B03C1/02—Magnetic separation acting directly on the substance being separated
- B03C1/30—Combinations with other devices, not otherwise provided for
Abstract
ABSTRACT OF THE DISCLOSURE
A process for separating relatively fine solid particles differing in size and specific gravity by the use of a heavy medium which includes magnetizable particles where a mixture containing the fine particles to be recovered and the heavy medium are fed under pressure to a specific gravity separating cyclone which divides the mixture into a ? tively fine specifically light fraction from which the magnetizable particles of the heavy medium are subsequently removed for re-use in the system while the diluted flow of the fine specifically light particles to be recovered is fed to a thickening cyclone which separates the bulk of the particles from the carrying liquid; the fine particles are then recovered from a filter screen while a portion of the liquid is further used in the process to facilitated recovery of the magnetic particles from the specifically heavy fraction derived from the cyclone.
A process for separating relatively fine solid particles differing in size and specific gravity by the use of a heavy medium which includes magnetizable particles where a mixture containing the fine particles to be recovered and the heavy medium are fed under pressure to a specific gravity separating cyclone which divides the mixture into a ? tively fine specifically light fraction from which the magnetizable particles of the heavy medium are subsequently removed for re-use in the system while the diluted flow of the fine specifically light particles to be recovered is fed to a thickening cyclone which separates the bulk of the particles from the carrying liquid; the fine particles are then recovered from a filter screen while a portion of the liquid is further used in the process to facilitated recovery of the magnetic particles from the specifically heavy fraction derived from the cyclone.
Description
BACKGROUND AND BRIEF DESCRIPTION OF THE_INVENTION
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The present invention relates to the field of particle separation and, more specifically, to recovery of a fine grade coal by means of heavy media suspensions.
A~ a result oi the increasing scarcity of raw materials and fuels, it is desirable to recover as much usable coal as is economically and physically possible.
As is well known, one of the chief difficulties in using coal as a fuel is the pollution that results as a consequence of the .
high sulfur content in the coal. It has been found, however, that very fine coal is relatively free of sulfur thus rendering the recovery of fine coal fractions highly desirable.
A number of processes have been developed for recovering fine coal on the order of 0.5 mm or smaller. One such process is froth flota~ion, which is, however, less suitable for some types o coal. For instance, oxidized coal cannot efficiently be recovered by froth flotation. A more suitable process is then a separation according to specific gravity using liquid separating media.
It has been proposed to remove the fine pa~ticles from a raw coal feed product containing also coarser particles in a classifying step, usually called de-sliming, and separating these fine particles into a fine light fTaction and a fine heavy fraction in a separate separating system. To obtain a high efficiency, the classifying step is usually carried out by screening while rinsing the product being screened with water. This involves the introduction o an amount of water which has a diluting effect on the separating medium that has to be compensated for by increasing the specific gravity of the heavy medillm with which the product is mixed prior to the specific gravity separation.
~0 According to United States Patent 2,932,395 of April 20, lg60, ~Paul Marot), this drawback can be eliminated by rinsing the product being screened with heavy medium in lieu of water. However, as a practical matter, in this process, the de-sliming has to be carried out with a large amount of heavy medium to avoid unsatisfactory removal of the fine particles and accumulation thereof in the heavy medium circulating through the process.
As a consequence, the finP particles fed to the separate separating system, which consists of one or more heavy medium cyclones, are accompanied by a ~' :
' ~, :
~L8723 comparatively large a unt of heavy n~edium and the solids concentration in the feed to the hydrocyclone(s) is lower than aclmissible ~or an efficient separa-tion. As a result, the amount of heavy medium to be treated is substantially increased and the capital investment or the equipment in the medium cleaning system is increased correspondingly~ Also, the screening equipment required for the classifying step adds substantially to the capital investment of the plant.
Apart from the initial capital investment in constructing a separat-ing process plant, one of the major cost factors in running such plants resides in the consumption of fresh water needed to efficiently carry out the process and the treatment of the amount of water circulating in the process. Accord-ingly, the prior art has endeavored to reduce the consumption of fresh water requlred to successfully effect coal washing and particle separation. How-e~er, such prooesses have, in general~ resulted in an increase in equipment cost per unit quantity of coal processed per unit of time as a consequence of the necessity of clarifying or purifying the water used in the process.
Further disclosures representative of the prior art in this field are U.S. Patent 2,387,866 of October 30,1945, (Godfrey ~Wal~er); U.S. Pa~ent
. . ;
The present invention relates to the field of particle separation and, more specifically, to recovery of a fine grade coal by means of heavy media suspensions.
A~ a result oi the increasing scarcity of raw materials and fuels, it is desirable to recover as much usable coal as is economically and physically possible.
As is well known, one of the chief difficulties in using coal as a fuel is the pollution that results as a consequence of the .
high sulfur content in the coal. It has been found, however, that very fine coal is relatively free of sulfur thus rendering the recovery of fine coal fractions highly desirable.
A number of processes have been developed for recovering fine coal on the order of 0.5 mm or smaller. One such process is froth flota~ion, which is, however, less suitable for some types o coal. For instance, oxidized coal cannot efficiently be recovered by froth flotation. A more suitable process is then a separation according to specific gravity using liquid separating media.
It has been proposed to remove the fine pa~ticles from a raw coal feed product containing also coarser particles in a classifying step, usually called de-sliming, and separating these fine particles into a fine light fTaction and a fine heavy fraction in a separate separating system. To obtain a high efficiency, the classifying step is usually carried out by screening while rinsing the product being screened with water. This involves the introduction o an amount of water which has a diluting effect on the separating medium that has to be compensated for by increasing the specific gravity of the heavy medillm with which the product is mixed prior to the specific gravity separation.
~0 According to United States Patent 2,932,395 of April 20, lg60, ~Paul Marot), this drawback can be eliminated by rinsing the product being screened with heavy medium in lieu of water. However, as a practical matter, in this process, the de-sliming has to be carried out with a large amount of heavy medium to avoid unsatisfactory removal of the fine particles and accumulation thereof in the heavy medium circulating through the process.
As a consequence, the finP particles fed to the separate separating system, which consists of one or more heavy medium cyclones, are accompanied by a ~' :
' ~, :
~L8723 comparatively large a unt of heavy n~edium and the solids concentration in the feed to the hydrocyclone(s) is lower than aclmissible ~or an efficient separa-tion. As a result, the amount of heavy medium to be treated is substantially increased and the capital investment or the equipment in the medium cleaning system is increased correspondingly~ Also, the screening equipment required for the classifying step adds substantially to the capital investment of the plant.
Apart from the initial capital investment in constructing a separat-ing process plant, one of the major cost factors in running such plants resides in the consumption of fresh water needed to efficiently carry out the process and the treatment of the amount of water circulating in the process. Accord-ingly, the prior art has endeavored to reduce the consumption of fresh water requlred to successfully effect coal washing and particle separation. How-e~er, such prooesses have, in general~ resulted in an increase in equipment cost per unit quantity of coal processed per unit of time as a consequence of the necessity of clarifying or purifying the water used in the process.
Further disclosures representative of the prior art in this field are U.S. Patent 2,387,866 of October 30,1945, (Godfrey ~Wal~er); U.S. Pa~ent
2~623,637 of Dece~ber 30, 1952, (Freerk J. Fontein); U.S. Patent 2,984,355 o 2Q May 16, 1961, (Jan N.J. Leeman~ and U.S. Patent 2,998,882 of September 5, 19~1, ~Jan ~.J. Leeman).
It is an object of the present invention to provide a coal cleaning and recovery process which effects a substantial saving in capital investment and also in the quantity of water required in the process.
Further, it is an object of the present invention to provide a separating process capable of recovering extremely fine particles of coal as well as for providing a process that has an inherent flexibility in selecting ~' the level of discrimination among the particles of coal and refuse to be recovered.
The invention relates to a continuous process for separ-ating a mixture of solid particles differing in size and specific gravity with the aid of a heavy medium comprising magnetizable particles as weighting material including the steps of:
(a) feeding said mixture to a first separating means to aivide said mixture into a specifically heavy and a specifically light fraction, (b) feeding said specifically light fraction over a first draining screen means and a first washing screen means and said specifically heavy fraction over a second draining screen means and a second washing screen means while spraying a liquid onto said fract~ons on each said washing screen means and recover-ing a washed relatively coarse fraction from each of said specif-ically heavy and light fractions and undiluted suspensions contain~
ing relatively fine specifically light and heavy particles from said first and second draining screen means, and dilute suspensions containing relatively fine particles from said first and second washing screen means, (c) re-cycling a portion of said unailuted suspensions to said separating means, The process of the invention is characterized by the further steps of:
mixing the remaining portions of said undiluted suspen-sions and feeding the resultant mixture to a second separating means to divide the relatively fine particles contained therein into a relatively fine specifically light fraction and a relatively _ 4~L
~L187Z3 fine specifically heavy fraction, combining said relatively fine specifically light fraction with the diluted suspension from said first washing screen means to form a first combined suspension and combining said relatively fine specifically heavy fraction with the diluted suspension from said second washing screen means to form a second combined suspen-sion and separately subjecting said first and second combined sus-pensions to magnetic separation, recovering the bulk of the relatively fine specifically light particles from the suspension remaining after removal of the magnetizable particles from said first combined suspension and using at least a portion of the remaining liquid for diluting said second combined suspension prior to subjecting said second combined suspension to said magnetic separation, removing the bulk of the solids comprising the fine specifically heavy particles from the suspension of non-magnetiz-able particles remaining after the removal of the magnetizable particles from said second combined suspension by magnetic separ-ation, and re-cycling the remaining liquid for re-use in the process.
~ith this arrangement, the necessity of using large quant-ities of either clarified or fresh water in the recovery of the magnetic particles at this stage of the process can be entirely eliminated without any significant reduction in the proportion of magnetic particles recovered. Reference is made to our copending application No. 268,991 in which a related process is claimed. The foregoing and other advantages of the process according to the in-vention will become apparent as consideration is given to the following detaiLed description of the invention and accompanying - 4a -, l~lB~2~
drawing in which:
~RIEF DESCRIPTION OF THE DRAWING
The drawing is a sehematic illustration of the various stages of one proeess of the present invention wherein the lines represent eonduits and the arrows the direction of flow in each conduit.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawing, raw coal which is a mixture of eoal, shale and various refuse partieles which has first been sereened to remove all particles larger than a predetermined size sueh as, for example, approximately a half-ineh, is introdueed into a mixing tank 10 together with a suspension of magnetizable part-ieles which may include re-eyeled fine eoal and refuse e ements at 12.
From the outlet of the mixing tank 10, the mixture of raw coal and separating suspension is fed to a first separating stage which may eonsist of a heavy medium cyelone 14, or a plural-ity of heavy medium eyelones in parallel of whieh function it is to separate the raw coal mixture according to -the density of the partieles. Thus, a relatively liyht fraction will be delivered from the first separating stage 14 and introduced through a con-duit 16 to a first draining screen means 18 while a relatively heavy fraction will be introduced through a conduit 20 to a second draining screen means 22.
Coarse particles of a size larger than the apertures of the draining sereen means lB and 22, e.g. +0.5 mm, will pass to washing sereens 24 and 26, respeetively, from whenee they will be ~ {
`' diseharged from the proeess.
- Y~
`
~ ~8723 In the first separating stage 14 only the relatively coarse particles are adequately separated according to density.
The separation of the relatively fine particles contained in the suspensions passing through the screens is insufficient.
A portion of the undiluted separating suspensions contain-ing fine coal and refuse particles that have passed through the draining screen means 18 and 22 is passed directly to a heavy medium sump 28 wh~ch is also employed to adjust the specific grav-ity of the separating suspension collected therein before it is recycled through conduit 12 to the mixing tank 10.
Another portion of the undiluted suspension passing through screen means 18 is passed to a sump tank 30 in which the dilute medium is collected which is obtained from washing screen 24 where the coarse light fraction is continuously washed by clarified liquid or fresh water from sprays 32 or from a re-cycled liquid as from 34 _ 5a -'~
which is obtained as described hereinafter. It will be apparent that the sump tank 30 will contain fine particles of coal, e.g. - 0,5 mm, as well as magnetizable particles in a diluted suspension.
Similarly, another portion of the undiluted heavy ~raction from the second draining screen means 22 is passed to a sump tank 36 in which diluted suspension is collected which is obtained from washing screen 26 where the coarse heavy fraction is washed with liquids from the same sources as the liquid for washing the coarse light fraction as indicated in the drawing. Thus, sump tank 36 contains a diluted separating suspension and relatively fine heavy particles.
Alternatively, it is possible to feed another portion of the combined undiluted drawings from first and second drain screens 18 and 22 to sump tank 38.
This sump also receives separating suspension recovered elsewhere in the process from the distribution box 42.
The specific gravity of the separating suspension in the sump 38 is carefully controlled, e.g., by the addition of a diluting liquid from pipe 33.
According to the present invention, it is desired to recover 20 the fine coal particles from the mixture in sump tank 38 while not only not increasing the consumption of water required to run the process but, in fact, by a reduction and conservation in terms of the water used as contrasted with the processes of the prior art. This i~ in addition to the water saving achieved by eliminating the de-sliming screens upstream of the first separating stage 14.
To this end, a pump 44, of conventional structure, is employed to pump the mixture from sump tank 38 to a heavy medium cyclone 46 or a plurality of heavy medium cyclones so that the mixture introduced into the heavy medium cyclone 46 is under pressure, such 30 as on the order of the equivalent of approxima~ely 30 feet of feed mixture. The pressure, in any event, should not be below 25 feet of feed mixture. The heavy medium cyclone 46 has smaller dimensions than the heavy mediu~ cyclone 14.
With this arrangement, a more efficient separation of fine 35 particles can be achieved than is possible with a cyclone of larger diameter.
~B723 The heavy medium cyclone 46~ with the specific gravity of the mi~ture in sump 38 properiy selected, will divide the mixture into a relati-vely fine specifically light fraction, which exits at the top of the heavy medium cyclone 46, and a relatively fine specifically heavy fraction which exits at the bottom thereof.
The light fraction is passed to a mixing tank 4~ where diluted suspension from sump 30 is added and, if desired, liquid through conduit 50 in order to form a diluted fraction including the relatively fine light particles From mixing tank 48 this diluted fraction is subjected to magnetic separation, However, to improve the efficiency of the magnetlc separation process, the diluted fraction of relatively fine light particles is first passed over a classifying means 52 such as a sieve bend in order to rapidly and efficiently separate out coal particles of an average size greater than a predetermined size. The principal object of classifying the first diluted fraction is to optimally remove fine non-magnetic particles from the magnetic particles and thus prevent a~cumulation of non-magnetic particles in the circulating separating suspension. The larger sized coal particles which are accompanied by a small amount of magnetizable particles are next diluted through conduit 54 with a liquid, the origin of which will be described herein after, and then the larger particles are passed to a first magnetic separator 56 which removes a major portion of the magnetic particles from the mixture. Then, the diluted fraction of larger particles is passed to a second magnetic separator 58 which effects removal of substantially all of the magnetic particles and delivers them to a conduit 60 which passes the thus recovered magnetic particles to sump 40 while the recovered and separated coal particles together with the bulk of the liquid are fed to a sump 62.
The finer coal particles, the magnetic particles and the liquid that pass through the classifying means 52 are similarly, if desired after dilution, treated in third and fourth magnetic separators, 64 and 66, respec-.
' tively, with the recovered coal particles delivered also to sump 62 while the magnetizable particles are fed to conduit 6n. The contents of sump 62, there-fore, is a diluted fraction of substantially only fine coal particles.
. ~
: : :
:: : :; , : : : :
- ;. ~
It is an object of the present invention to provide a coal cleaning and recovery process which effects a substantial saving in capital investment and also in the quantity of water required in the process.
Further, it is an object of the present invention to provide a separating process capable of recovering extremely fine particles of coal as well as for providing a process that has an inherent flexibility in selecting ~' the level of discrimination among the particles of coal and refuse to be recovered.
The invention relates to a continuous process for separ-ating a mixture of solid particles differing in size and specific gravity with the aid of a heavy medium comprising magnetizable particles as weighting material including the steps of:
(a) feeding said mixture to a first separating means to aivide said mixture into a specifically heavy and a specifically light fraction, (b) feeding said specifically light fraction over a first draining screen means and a first washing screen means and said specifically heavy fraction over a second draining screen means and a second washing screen means while spraying a liquid onto said fract~ons on each said washing screen means and recover-ing a washed relatively coarse fraction from each of said specif-ically heavy and light fractions and undiluted suspensions contain~
ing relatively fine specifically light and heavy particles from said first and second draining screen means, and dilute suspensions containing relatively fine particles from said first and second washing screen means, (c) re-cycling a portion of said unailuted suspensions to said separating means, The process of the invention is characterized by the further steps of:
mixing the remaining portions of said undiluted suspen-sions and feeding the resultant mixture to a second separating means to divide the relatively fine particles contained therein into a relatively fine specifically light fraction and a relatively _ 4~L
~L187Z3 fine specifically heavy fraction, combining said relatively fine specifically light fraction with the diluted suspension from said first washing screen means to form a first combined suspension and combining said relatively fine specifically heavy fraction with the diluted suspension from said second washing screen means to form a second combined suspen-sion and separately subjecting said first and second combined sus-pensions to magnetic separation, recovering the bulk of the relatively fine specifically light particles from the suspension remaining after removal of the magnetizable particles from said first combined suspension and using at least a portion of the remaining liquid for diluting said second combined suspension prior to subjecting said second combined suspension to said magnetic separation, removing the bulk of the solids comprising the fine specifically heavy particles from the suspension of non-magnetiz-able particles remaining after the removal of the magnetizable particles from said second combined suspension by magnetic separ-ation, and re-cycling the remaining liquid for re-use in the process.
~ith this arrangement, the necessity of using large quant-ities of either clarified or fresh water in the recovery of the magnetic particles at this stage of the process can be entirely eliminated without any significant reduction in the proportion of magnetic particles recovered. Reference is made to our copending application No. 268,991 in which a related process is claimed. The foregoing and other advantages of the process according to the in-vention will become apparent as consideration is given to the following detaiLed description of the invention and accompanying - 4a -, l~lB~2~
drawing in which:
~RIEF DESCRIPTION OF THE DRAWING
The drawing is a sehematic illustration of the various stages of one proeess of the present invention wherein the lines represent eonduits and the arrows the direction of flow in each conduit.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawing, raw coal which is a mixture of eoal, shale and various refuse partieles which has first been sereened to remove all particles larger than a predetermined size sueh as, for example, approximately a half-ineh, is introdueed into a mixing tank 10 together with a suspension of magnetizable part-ieles which may include re-eyeled fine eoal and refuse e ements at 12.
From the outlet of the mixing tank 10, the mixture of raw coal and separating suspension is fed to a first separating stage which may eonsist of a heavy medium cyelone 14, or a plural-ity of heavy medium eyelones in parallel of whieh function it is to separate the raw coal mixture according to -the density of the partieles. Thus, a relatively liyht fraction will be delivered from the first separating stage 14 and introduced through a con-duit 16 to a first draining screen means 18 while a relatively heavy fraction will be introduced through a conduit 20 to a second draining screen means 22.
Coarse particles of a size larger than the apertures of the draining sereen means lB and 22, e.g. +0.5 mm, will pass to washing sereens 24 and 26, respeetively, from whenee they will be ~ {
`' diseharged from the proeess.
- Y~
`
~ ~8723 In the first separating stage 14 only the relatively coarse particles are adequately separated according to density.
The separation of the relatively fine particles contained in the suspensions passing through the screens is insufficient.
A portion of the undiluted separating suspensions contain-ing fine coal and refuse particles that have passed through the draining screen means 18 and 22 is passed directly to a heavy medium sump 28 wh~ch is also employed to adjust the specific grav-ity of the separating suspension collected therein before it is recycled through conduit 12 to the mixing tank 10.
Another portion of the undiluted suspension passing through screen means 18 is passed to a sump tank 30 in which the dilute medium is collected which is obtained from washing screen 24 where the coarse light fraction is continuously washed by clarified liquid or fresh water from sprays 32 or from a re-cycled liquid as from 34 _ 5a -'~
which is obtained as described hereinafter. It will be apparent that the sump tank 30 will contain fine particles of coal, e.g. - 0,5 mm, as well as magnetizable particles in a diluted suspension.
Similarly, another portion of the undiluted heavy ~raction from the second draining screen means 22 is passed to a sump tank 36 in which diluted suspension is collected which is obtained from washing screen 26 where the coarse heavy fraction is washed with liquids from the same sources as the liquid for washing the coarse light fraction as indicated in the drawing. Thus, sump tank 36 contains a diluted separating suspension and relatively fine heavy particles.
Alternatively, it is possible to feed another portion of the combined undiluted drawings from first and second drain screens 18 and 22 to sump tank 38.
This sump also receives separating suspension recovered elsewhere in the process from the distribution box 42.
The specific gravity of the separating suspension in the sump 38 is carefully controlled, e.g., by the addition of a diluting liquid from pipe 33.
According to the present invention, it is desired to recover 20 the fine coal particles from the mixture in sump tank 38 while not only not increasing the consumption of water required to run the process but, in fact, by a reduction and conservation in terms of the water used as contrasted with the processes of the prior art. This i~ in addition to the water saving achieved by eliminating the de-sliming screens upstream of the first separating stage 14.
To this end, a pump 44, of conventional structure, is employed to pump the mixture from sump tank 38 to a heavy medium cyclone 46 or a plurality of heavy medium cyclones so that the mixture introduced into the heavy medium cyclone 46 is under pressure, such 30 as on the order of the equivalent of approxima~ely 30 feet of feed mixture. The pressure, in any event, should not be below 25 feet of feed mixture. The heavy medium cyclone 46 has smaller dimensions than the heavy mediu~ cyclone 14.
With this arrangement, a more efficient separation of fine 35 particles can be achieved than is possible with a cyclone of larger diameter.
~B723 The heavy medium cyclone 46~ with the specific gravity of the mi~ture in sump 38 properiy selected, will divide the mixture into a relati-vely fine specifically light fraction, which exits at the top of the heavy medium cyclone 46, and a relatively fine specifically heavy fraction which exits at the bottom thereof.
The light fraction is passed to a mixing tank 4~ where diluted suspension from sump 30 is added and, if desired, liquid through conduit 50 in order to form a diluted fraction including the relatively fine light particles From mixing tank 48 this diluted fraction is subjected to magnetic separation, However, to improve the efficiency of the magnetlc separation process, the diluted fraction of relatively fine light particles is first passed over a classifying means 52 such as a sieve bend in order to rapidly and efficiently separate out coal particles of an average size greater than a predetermined size. The principal object of classifying the first diluted fraction is to optimally remove fine non-magnetic particles from the magnetic particles and thus prevent a~cumulation of non-magnetic particles in the circulating separating suspension. The larger sized coal particles which are accompanied by a small amount of magnetizable particles are next diluted through conduit 54 with a liquid, the origin of which will be described herein after, and then the larger particles are passed to a first magnetic separator 56 which removes a major portion of the magnetic particles from the mixture. Then, the diluted fraction of larger particles is passed to a second magnetic separator 58 which effects removal of substantially all of the magnetic particles and delivers them to a conduit 60 which passes the thus recovered magnetic particles to sump 40 while the recovered and separated coal particles together with the bulk of the liquid are fed to a sump 62.
The finer coal particles, the magnetic particles and the liquid that pass through the classifying means 52 are similarly, if desired after dilution, treated in third and fourth magnetic separators, 64 and 66, respec-.
' tively, with the recovered coal particles delivered also to sump 62 while the magnetizable particles are fed to conduit 6n. The contents of sump 62, there-fore, is a diluted fraction of substantially only fine coal particles.
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3'723 According to the present invention the diluted fraction in sump 62 is passed through pump 68 to a thickening cyclone 70, the structure and operation of ~hich is well known in this art. Thickening cyclone 70 effects separation of the bulk of the fine coal particles from the liquid whereby the coal particles exit at the bottom of the cyclone and are passed to a de-watering means 72, such as a filter screen, from which the coal particles 3re recovered while the liquid is passed back to sump 62 for re-use in the process. The liquid recovered from the diluted fraction fed to thickening cyclone 70 exits from the top of this cyclone and is- fed to a head tank 74. Thereafter, a portion of the recovered liquid is passed to sprays 34 to be used as rinsing water and another portion of it to a mi~ing tank 76 where it is combined with the heavy fraction separated from the mixture fed to the heavy media cyclone 46. This heavy fraction will comprise generally refuse particles and magnetizable particles. It is desirable, of course, according to the present invention, to recover also these magnetizable particles for re-use in the system while conserving or reducing the liquid required to efficiently carry out such a recovery.
Thus, the liq~lid separated from the first diluted fraction is employed 20 a~ this point to facilitate efficient separation and recovery of these magnetizable particles by being combined with the heavy fraction to form a second diluted fraction.
From tank 76 the second diluted fraction is passed to classifying means 78 such as the sieve bend which, as in the previous 25 circumstance, separates the larger si2ed fraction refuse particles from the second diluted fraction. The larger size particles are then diluted through conduit 80 with another portion of the liquid separated from thickening cyclone 70 to permit efficient separation in the first magnetic separator 82 which is followed by a second magnetic separator 84. The magnetic particles recovered from these magnetic separators 82 and 84 are passed to the heavy medium sump 40 so that they can be introduced into the initial separation stage of this process. Likewise, the second dilutcd fraction passing through sieve bend 78 is passed, if desired after dilution, to third and fourth magnetic separators 86 and 88, respectively. The magnetizable particles recovered from these separators are also passed back to the sump 40 while the .
~8~723 mixture of refuse particles and water from the magnetic separators 82-88 is passed to a thickener 90 which eliminates the refuse part-icles at 92 from the process while returning clarified liquid at 94 to the head tank 74 thereby resulting in additional conservation of water. Tank 94 also coll.ects the overflow from thickener 90 and head tank 74 and, if necessary, fresh water may be added to tank 94 as through a conduit 93.
It will be apparent that with the process of the present invention running within the rated capacity of the various elements thereof, a liquid balance can be readily achieved and maintained particularly from the sump 38 to the filter screen 72 while in-cluding the recovery of both fine coal particles of a size 0.5 to 0 mm and magnetizable particles from the fractions separated in heavy medium cyclone 46. It is also believed apparent that the total quantity of water required to operate the system for a given raw product input per hour will be substantially less than has previously been the case where the separation of the fine coal products is to the same degree of particle size~
Also of significance is the efficiency of the process in terms of the size of the fine particles of coal that can be re-covered, while conserving water, without the addition of expensive de-sliming screens or a multiplicity of settling tanks or thickeners.
Having described the invention, it will ~e obvious to those skilled in the art that various modifications may be made in the process of the present invention without departing from the spirit and scope thereof as defined in the appended claims.
_ g ~:~18723 feed the mixture containing the fine particles to a sump 38 and then through the separation process including a secondary heavy medium cyclone 46, as in the embodiment of Figure 1. Instead, a portion of the undiluted suspension ~rom the first draining screen means 18' can be combined with all of the diluted suspension from the first washing screen 24' in sump 30' and the con~ined suspensions can be fed directly through conduit 98' to mixing tank 4S' for the magnetic separation. Likewise~ a portion of the undiluted suspension from the second draining screen means 22' can be combined with the diluted suspension from the second washing screen 26' in sump 36' to form a mixture that can be subjected directly to magnetic separation from mixing tank 76'. The recovered concentrated separating suspension is fed to sump tank 28' through conduits 95' and 96~.
Having described the invention, it will be obvious to those s~illed in the art that various modifications may be made in the process of the present invention without departing from the spirit and scope thereof as defined in the appended claims.
,, ~
Thus, the liq~lid separated from the first diluted fraction is employed 20 a~ this point to facilitate efficient separation and recovery of these magnetizable particles by being combined with the heavy fraction to form a second diluted fraction.
From tank 76 the second diluted fraction is passed to classifying means 78 such as the sieve bend which, as in the previous 25 circumstance, separates the larger si2ed fraction refuse particles from the second diluted fraction. The larger size particles are then diluted through conduit 80 with another portion of the liquid separated from thickening cyclone 70 to permit efficient separation in the first magnetic separator 82 which is followed by a second magnetic separator 84. The magnetic particles recovered from these magnetic separators 82 and 84 are passed to the heavy medium sump 40 so that they can be introduced into the initial separation stage of this process. Likewise, the second dilutcd fraction passing through sieve bend 78 is passed, if desired after dilution, to third and fourth magnetic separators 86 and 88, respectively. The magnetizable particles recovered from these separators are also passed back to the sump 40 while the .
~8~723 mixture of refuse particles and water from the magnetic separators 82-88 is passed to a thickener 90 which eliminates the refuse part-icles at 92 from the process while returning clarified liquid at 94 to the head tank 74 thereby resulting in additional conservation of water. Tank 94 also coll.ects the overflow from thickener 90 and head tank 74 and, if necessary, fresh water may be added to tank 94 as through a conduit 93.
It will be apparent that with the process of the present invention running within the rated capacity of the various elements thereof, a liquid balance can be readily achieved and maintained particularly from the sump 38 to the filter screen 72 while in-cluding the recovery of both fine coal particles of a size 0.5 to 0 mm and magnetizable particles from the fractions separated in heavy medium cyclone 46. It is also believed apparent that the total quantity of water required to operate the system for a given raw product input per hour will be substantially less than has previously been the case where the separation of the fine coal products is to the same degree of particle size~
Also of significance is the efficiency of the process in terms of the size of the fine particles of coal that can be re-covered, while conserving water, without the addition of expensive de-sliming screens or a multiplicity of settling tanks or thickeners.
Having described the invention, it will ~e obvious to those skilled in the art that various modifications may be made in the process of the present invention without departing from the spirit and scope thereof as defined in the appended claims.
_ g ~:~18723 feed the mixture containing the fine particles to a sump 38 and then through the separation process including a secondary heavy medium cyclone 46, as in the embodiment of Figure 1. Instead, a portion of the undiluted suspension ~rom the first draining screen means 18' can be combined with all of the diluted suspension from the first washing screen 24' in sump 30' and the con~ined suspensions can be fed directly through conduit 98' to mixing tank 4S' for the magnetic separation. Likewise~ a portion of the undiluted suspension from the second draining screen means 22' can be combined with the diluted suspension from the second washing screen 26' in sump 36' to form a mixture that can be subjected directly to magnetic separation from mixing tank 76'. The recovered concentrated separating suspension is fed to sump tank 28' through conduits 95' and 96~.
Having described the invention, it will be obvious to those s~illed in the art that various modifications may be made in the process of the present invention without departing from the spirit and scope thereof as defined in the appended claims.
,, ~
Claims
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
A continuous process for separating a mixture of solid par-ticles differing in size and specific gravity with the aid of a heavy medium comprising magnetizable particles as weighting material including the steps of:
(a) feeding said mixture to a first separating means to divide said mixture into a specifically heavy and a spe-cifically light fraction, (b) feeding said specifically light fraction over a first draining screen means and a first washing screen means and said specifically heavy fraction over a second draining screen means and a second washing screen means while spraying a liquid onto said fractions on each said washing screen means and recovering a washed relatively coarse fraction from each of said specifically heavy and light fractions and undiluted suspensions containing relatively fine specifically light and heavy particles from said first and second draining screen means, and dilute suspensions containing relatively fine particles from said first and second washing screen means, (c) re-cycling a portion of said undiluted suspensions to said separating means, characterized by the further steps of:
mixing the remaining portions of said undiluted suspensions and feeding the resultant mixture to a second separating means to divide the relatively fine particles contained therein into a relatively fine specifically light fraction and a relatively fine specifically heavy fraction, combining said relatively fine specifically light fraction with the diluted suspension from said first washing screen means to form a first combined suspension and combining said relatively fine specifically heavy fraction with the diluted suspension from said second washing screen means to form a second combined suspension and separately subjecting said first and second combined suspensions to magnetic separation, recovering the bulk of the relatively fine specifically light particles from the suspension remaining after removal of the magnetizable particles from said first combined suspension and using at least a portion of the remaining liquid for diluting said second combined suspension prior to subjecting said second combined suspension to said magnetic separation, removing the bulk of the solids comprising the fine specifi-cally heavy particles from the suspension of non-magnetizable particles remaining after the removal of the magnetizable particles from said second combined suspension by magnetic separation, and re-cycling the remaining liquid for re-use in the process.
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
A continuous process for separating a mixture of solid par-ticles differing in size and specific gravity with the aid of a heavy medium comprising magnetizable particles as weighting material including the steps of:
(a) feeding said mixture to a first separating means to divide said mixture into a specifically heavy and a spe-cifically light fraction, (b) feeding said specifically light fraction over a first draining screen means and a first washing screen means and said specifically heavy fraction over a second draining screen means and a second washing screen means while spraying a liquid onto said fractions on each said washing screen means and recovering a washed relatively coarse fraction from each of said specifically heavy and light fractions and undiluted suspensions containing relatively fine specifically light and heavy particles from said first and second draining screen means, and dilute suspensions containing relatively fine particles from said first and second washing screen means, (c) re-cycling a portion of said undiluted suspensions to said separating means, characterized by the further steps of:
mixing the remaining portions of said undiluted suspensions and feeding the resultant mixture to a second separating means to divide the relatively fine particles contained therein into a relatively fine specifically light fraction and a relatively fine specifically heavy fraction, combining said relatively fine specifically light fraction with the diluted suspension from said first washing screen means to form a first combined suspension and combining said relatively fine specifically heavy fraction with the diluted suspension from said second washing screen means to form a second combined suspension and separately subjecting said first and second combined suspensions to magnetic separation, recovering the bulk of the relatively fine specifically light particles from the suspension remaining after removal of the magnetizable particles from said first combined suspension and using at least a portion of the remaining liquid for diluting said second combined suspension prior to subjecting said second combined suspension to said magnetic separation, removing the bulk of the solids comprising the fine specifi-cally heavy particles from the suspension of non-magnetizable particles remaining after the removal of the magnetizable particles from said second combined suspension by magnetic separation, and re-cycling the remaining liquid for re-use in the process.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US835,031 | 1977-09-20 | ||
| US05/835,031 US4144164A (en) | 1977-09-20 | 1977-09-20 | Process for separating mixtures of particles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1118723A true CA1118723A (en) | 1982-02-23 |
Family
ID=25268402
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000311557A Expired CA1118723A (en) | 1977-09-20 | 1978-09-19 | Heavy magnetic media hydrocyclonic separation process with screening, magnetic separation and recycling of liquids |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4144164A (en) |
| AU (1) | AU517742B2 (en) |
| CA (1) | CA1118723A (en) |
| ZA (1) | ZA785177B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108097451A (en) * | 2018-01-27 | 2018-06-01 | 华北科技学院 | A kind of coal separation station-service magnetic separation process flow |
| EP3523008A4 (en) * | 2016-10-05 | 2020-05-20 | Khalifa University of Science and Technology | Process for heat stable salts removal from solvents |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1139273B (en) * | 1981-10-22 | 1986-09-24 | Prominco Srl | PROCEDURE FOR DYNAMIC SEPARATION BY MEANS OF MIXTURES OF MATERIALS, SUCH AS MINERALS FOR EXAMPLE, WITH DIFFERENT SPECIFIC WEIGHT, AND PLANT TO IMPLEMENT IT |
| FR2550103B1 (en) * | 1983-08-02 | 1989-12-01 | Fives Cail Babcock | PROCESS FOR DENSIMETRIC SEPARATION OF PARTICLES BY HYDROCYCLONING IN A DENSE MEDIUM AND INSTALLATION FOR CARRYING OUT SAID METHOD |
| US4802976A (en) * | 1988-01-04 | 1989-02-07 | Miller Francis G | Method for recovering fine clean coal |
| US6355178B1 (en) | 1999-04-02 | 2002-03-12 | Theodore Couture | Cyclonic separator with electrical or magnetic separation enhancement |
| US6085912A (en) * | 1999-07-13 | 2000-07-11 | Hacking, Jr.; Earl L. | Apparatus for sorting and recombining minerals background of the invention |
| WO2010043836A1 (en) * | 2008-10-15 | 2010-04-22 | Ath Regeneration Limited | Separation system and method |
| CN101455992B (en) * | 2008-12-10 | 2012-05-02 | 重庆南桐矿业有限责任公司南桐选煤厂 | Power coal and sulfur concentrate sorting method and special device thereof |
| BR112012005618B1 (en) | 2009-10-28 | 2020-03-10 | Magglobal, Llc | MAGNETIC SEPARATION DEVICE |
| CN102527495B (en) * | 2010-12-22 | 2014-04-16 | 佛冈县山深陶瓷原料有限公司 | Mineral separation process for non-metal ore |
| WO2012145658A1 (en) | 2011-04-20 | 2012-10-26 | Magnetation, Inc. | Iron ore separation device |
| RU2533792C2 (en) * | 2012-12-04 | 2014-11-20 | Федеральное государственное бюджетное учреждение науки Горный институт Кольского научного центра Российской академии наук | Method of obtaining of bulk concentrate from ferruginous quartzites |
| DE102014200415A1 (en) * | 2013-12-20 | 2015-06-25 | Siemens Aktiengesellschaft | Process for the separation of a defined mineral substance phase from a ground ore |
| CN105689109B (en) * | 2016-01-27 | 2018-01-30 | 中国矿业大学 | A kind of fine coal slurry medium solid cyclone separation of coarse slime method |
| CN106179717B (en) * | 2016-07-22 | 2018-04-10 | 中煤科工集团唐山研究院有限公司 | A kind of full level of thermal coal is selected in simplified heavy medium sorting process |
| CN109954582B (en) * | 2019-04-09 | 2021-04-06 | 安徽理工大学 | Separation method for coal slime water concentration and flotation system thereof |
| CN110075991A (en) * | 2019-04-19 | 2019-08-02 | 神华准格尔能源有限责任公司 | Dry-wet combined sorting system |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2623637A (en) * | 1948-08-20 | 1952-12-30 | Mij Voor Kolenbewering Stamica | System of separation |
| US2932395A (en) * | 1953-11-21 | 1960-04-12 | Stamicarbon | Process of separating mixtures of particles |
| GB791520A (en) * | 1953-12-24 | 1958-03-05 | Stamicarbon | Improvements in and relating to the wet screening of solid particles and apparatus therefor |
-
1977
- 1977-09-20 US US05/835,031 patent/US4144164A/en not_active Expired - Lifetime
-
1978
- 1978-09-12 ZA ZA00785177A patent/ZA785177B/en unknown
- 1978-09-14 AU AU39877/78A patent/AU517742B2/en not_active Expired
- 1978-09-19 CA CA000311557A patent/CA1118723A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3523008A4 (en) * | 2016-10-05 | 2020-05-20 | Khalifa University of Science and Technology | Process for heat stable salts removal from solvents |
| CN108097451A (en) * | 2018-01-27 | 2018-06-01 | 华北科技学院 | A kind of coal separation station-service magnetic separation process flow |
Also Published As
| Publication number | Publication date |
|---|---|
| AU3987778A (en) | 1980-03-20 |
| ZA785177B (en) | 1979-08-29 |
| AU517742B2 (en) | 1981-08-20 |
| US4144164A (en) | 1979-03-13 |
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