CA1269064A - Classification of solids in an aqueous pool by means of a moving floor - Google Patents
Classification of solids in an aqueous pool by means of a moving floorInfo
- Publication number
- CA1269064A CA1269064A CA000476196A CA476196A CA1269064A CA 1269064 A CA1269064 A CA 1269064A CA 000476196 A CA000476196 A CA 000476196A CA 476196 A CA476196 A CA 476196A CA 1269064 A CA1269064 A CA 1269064A
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- bitumen
- pool
- drum
- underflow
- overflow
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Abstract
ABSTRACT OF THE DISCLOSURE
An aqueous tar sand tailings slurry mixture containing coarse sand, fine particulate solids and bitumen is classified into an underflow of coarse wet sand and an overflow consisting of an aqueous suspension of fine solid particles and bitumen with the aid of a liquid pool on the top flight of a upwardly revolving inclined conveyor belt.
The mixture is introduced into the pool on the top flight wherein the coarse sand settles to the surface of the top flight as the underflow and the remaining fine solid particles and bitumen stay suspended in or float on the water of the mixture and flow out of the pool as the overflow. The underflow is removed by the surface of the revolving belt out of and above the surface of the aqueous pool. The underflow falls by gravity from the top flight as it passes by the upper conveyor roller The overflow is collected for subsequent recovery of its bitumen content.
The process is particularly suited for concentrating bitumen from mined tar sand tailings.
An aqueous tar sand tailings slurry mixture containing coarse sand, fine particulate solids and bitumen is classified into an underflow of coarse wet sand and an overflow consisting of an aqueous suspension of fine solid particles and bitumen with the aid of a liquid pool on the top flight of a upwardly revolving inclined conveyor belt.
The mixture is introduced into the pool on the top flight wherein the coarse sand settles to the surface of the top flight as the underflow and the remaining fine solid particles and bitumen stay suspended in or float on the water of the mixture and flow out of the pool as the overflow. The underflow is removed by the surface of the revolving belt out of and above the surface of the aqueous pool. The underflow falls by gravity from the top flight as it passes by the upper conveyor roller The overflow is collected for subsequent recovery of its bitumen content.
The process is particularly suited for concentrating bitumen from mined tar sand tailings.
Description
l~ti~ ti ~
CLASSIFICATION OF SOLIDS IN AN A~UEOUS POOL
~Y MEANS OF A MOVING FLOOR
This invention relates to a method for removing coarse solids from a mixture of particulate gangue, water, and fine particulat~ metals or minerals. More particularly, this invention relates ~o a method for removing lumps, rocks, gravel and coarse sand from a mixture of tar sand and water or from a mixture -~hat contains particulate solids and bitumen. The intent of the present invention is to remove coarse solids from such mixtures before processing so that in subsequent processing bitumen or valuable metals or minerals may be more conveniently recovered. This invention is particularly suitable for classifying materials into an overflow feed which is subsequently treated for the recovery of bitumen, metals or minerals by an oleophilic sieve.
This invention is primarily concerned with recovering bitumen from mined tar sands or from the effluent streams of commercial mined tar sand plants. This invention is also concerned with recovering metal and mineral values from low grade ores in which the metal or mineral values are present in very small particulate size. Extensive deposits of tar sand~, also known as oil sands and bituminous sands, are found in Northern Alberta, Canada. The sands are composed of silicious m~erial with grains generally having a size greater than that passing a 325 mesh screen (44 microns) and a t i ~3 ~
relatively heavy viscous petroleum called bitumen, which fills the void be-tween the grains in quantities of from 1 to 21 percent of total composition. (~11 percentages referred to herein are in weight percent unless noted otherwise.) Generally, the bitumen content of the sand is between 5 and 15 percent. A
typical bitumen contains about 4.5 percent sulfur, 38 percent aromatics, and has a specific gravity at 16 degrees C. which ranges from about 1.00 to about 1.06.
The tar sands also contain clay and silt. Silt is defined as silicious material which will pass a 325 mesh screen, but which is larger than 2 microns. Clay is material smaller than 2 microns, including some silicious material of that size.
Other tar sands deposits are also found elsewhere is the world, such as in the Orinoco heavy oil belt of Venezuela, in many of the African countries, in Russia and in the United States in the State of Utah. The mineral and bitumen of these deposits vary from place to place. For example, compared with the Alberta tar sands, the Utah tar sands contain a coarser sand, less clay, less water and an even more viscous bitumen.
Much of the world resource of bitumen and heavy oil is deeply buried by overburden. For example, it has been estimated that only about 10 percent of the Alberta tar sands deposit is close enough to the earth's surface to be conveniently recovered by mining. The remainder is buried too deeply to be economically surface mined.
3a Hydraulic mining or tunnel mining has been proposed for these deeper deposits. Generally, however, it is considered that enhanced recovery by steam injection, by injection of aqueous solutions, and/or by in-situ combustion may possibly be more effective for obtaining bitumen or heavy oil from deeply buried formations.
~ 3~
Such enhanced recovery methods use one or more oil wells that penetrate the formation and stimulate or recover the bitumen resource. Recovery of bitumen from a well by steam stimulation is described in Canadian Patent No. 822,985 granted on September 16, 1969 to Fred D. Muggee. Depending upon the procedure employed, enhanced recovery methods either produce mixtures of oil and water, water-in-oil emulsions or produce oil-in-water emulsions.
There are several well known procedures for separating bitumen from mined tar sands. One such method is known as the RHot Water Processn. In a hot water method, such as disclosed in Canadian Patent No. 841,581 issued May 12, 1979 to Paul H. Floyd, et al., the bituminous sands are jetted with steam and mulled with a minor amount of hot water and sodium hydroxide in a conditioning drum through a screen, which removes debris, rocks and oversize lumps, to a sump where it is diluted with additional water. It is thereafter carried into a separation cell.
In the separation cell, sand settles to the bottom as tailings which are discarded. Bitumen rises to the top of the cell in the form of a bituminous froth which is called the primary froth product. An aqueous middlings layer containing some mineral and bitumen is formed between these layers. A scavenging step is normally conducted on this middlings layer in a separate flotation zone. In this scavenging step, the middlings are aerated so as to produce a scavenger tailings product which is discarded and a scavenger froth product. The scavenger froth product is thereafter combined with the primary froth product for further treatment. This combined froth product typically contains about 52 percent bitumen, 6 percent mineral ti~3t~,4 matter, 41 percent water, and may contain fro~ 20 to 70 volume percent air. It resembles a liquid foam that is difficult to pump and, for that reason, is usually treated with steam to improve its flow characteristics.
The high water and mineral contents of the combined froth product normal]y are reduced by diluting it with a hydrocarbon diluent such as naptha. It is then centrifuged to produce a tailings product and a final bitumen product that typically contains essentially no water and about 1.3 percent solids and that is suitable for coking, hydrovisbreaking and other refining techniques for producing a synthetic crude oil. The tailings products, containing some naptha, are discarded.
There are basically four effluent streams from the Hot Water Process. Each carries with it some bitumen from the ~eed; thereby reducing the efficiency of the Process. These include the oversize material, the sand from the separation cells, the silt and clay from the scavenger cells and the tailings from the centrifuges.
Up to 30 percent of the bitumen in the original feed and up to 5 percent of the naptha stream may be lost in this manner. Much of this bitumen effluent finds its way into large retention or tailings ponds that are typical of the Hot Water Process. The bottom of such ponds may contain up to 50 percent dispersed mineral matter consisting substantially of clay and silt as well as up to 10 percent bitumen. As disclosed in Canadian Patent No. 975,697 issued on October 7, 1975 to Davitt H. James, this part of the pond contents, referred to as sludge or sediment, is a potential source of bitumen.
The ~lot Water Proce~s described in the preceeding paragraphs separates bitumen ~rom a slurry prepared from mined tar sands. The slurry is hot, contains finely dispersed air bubbles and the bitumen is in the form of small flecks. Such a slurry is amenable to subsequent separation in the Hot Water Process, after dilution with water, wherein bitumen forms into a roth that rises to the top of the bath and is skimmed therefrom. Alkaline reagents such as sodium hydroxide are normally added in this process to give the slurry those properties that provide for efficient flotation of the bitumen in said water. However, in the presence of sodium nydroxide, fine clay particles in the effluent streams deposited into the tailings ponds do not readily settle into a compacted solids layer. For that reason inordinately large settling ponds are required to contain the effluents from commercial hot water tar sands extraction plants.
With some mined tar sands, particularly with Utah tar
CLASSIFICATION OF SOLIDS IN AN A~UEOUS POOL
~Y MEANS OF A MOVING FLOOR
This invention relates to a method for removing coarse solids from a mixture of particulate gangue, water, and fine particulat~ metals or minerals. More particularly, this invention relates ~o a method for removing lumps, rocks, gravel and coarse sand from a mixture of tar sand and water or from a mixture -~hat contains particulate solids and bitumen. The intent of the present invention is to remove coarse solids from such mixtures before processing so that in subsequent processing bitumen or valuable metals or minerals may be more conveniently recovered. This invention is particularly suitable for classifying materials into an overflow feed which is subsequently treated for the recovery of bitumen, metals or minerals by an oleophilic sieve.
This invention is primarily concerned with recovering bitumen from mined tar sands or from the effluent streams of commercial mined tar sand plants. This invention is also concerned with recovering metal and mineral values from low grade ores in which the metal or mineral values are present in very small particulate size. Extensive deposits of tar sand~, also known as oil sands and bituminous sands, are found in Northern Alberta, Canada. The sands are composed of silicious m~erial with grains generally having a size greater than that passing a 325 mesh screen (44 microns) and a t i ~3 ~
relatively heavy viscous petroleum called bitumen, which fills the void be-tween the grains in quantities of from 1 to 21 percent of total composition. (~11 percentages referred to herein are in weight percent unless noted otherwise.) Generally, the bitumen content of the sand is between 5 and 15 percent. A
typical bitumen contains about 4.5 percent sulfur, 38 percent aromatics, and has a specific gravity at 16 degrees C. which ranges from about 1.00 to about 1.06.
The tar sands also contain clay and silt. Silt is defined as silicious material which will pass a 325 mesh screen, but which is larger than 2 microns. Clay is material smaller than 2 microns, including some silicious material of that size.
Other tar sands deposits are also found elsewhere is the world, such as in the Orinoco heavy oil belt of Venezuela, in many of the African countries, in Russia and in the United States in the State of Utah. The mineral and bitumen of these deposits vary from place to place. For example, compared with the Alberta tar sands, the Utah tar sands contain a coarser sand, less clay, less water and an even more viscous bitumen.
Much of the world resource of bitumen and heavy oil is deeply buried by overburden. For example, it has been estimated that only about 10 percent of the Alberta tar sands deposit is close enough to the earth's surface to be conveniently recovered by mining. The remainder is buried too deeply to be economically surface mined.
3a Hydraulic mining or tunnel mining has been proposed for these deeper deposits. Generally, however, it is considered that enhanced recovery by steam injection, by injection of aqueous solutions, and/or by in-situ combustion may possibly be more effective for obtaining bitumen or heavy oil from deeply buried formations.
~ 3~
Such enhanced recovery methods use one or more oil wells that penetrate the formation and stimulate or recover the bitumen resource. Recovery of bitumen from a well by steam stimulation is described in Canadian Patent No. 822,985 granted on September 16, 1969 to Fred D. Muggee. Depending upon the procedure employed, enhanced recovery methods either produce mixtures of oil and water, water-in-oil emulsions or produce oil-in-water emulsions.
There are several well known procedures for separating bitumen from mined tar sands. One such method is known as the RHot Water Processn. In a hot water method, such as disclosed in Canadian Patent No. 841,581 issued May 12, 1979 to Paul H. Floyd, et al., the bituminous sands are jetted with steam and mulled with a minor amount of hot water and sodium hydroxide in a conditioning drum through a screen, which removes debris, rocks and oversize lumps, to a sump where it is diluted with additional water. It is thereafter carried into a separation cell.
In the separation cell, sand settles to the bottom as tailings which are discarded. Bitumen rises to the top of the cell in the form of a bituminous froth which is called the primary froth product. An aqueous middlings layer containing some mineral and bitumen is formed between these layers. A scavenging step is normally conducted on this middlings layer in a separate flotation zone. In this scavenging step, the middlings are aerated so as to produce a scavenger tailings product which is discarded and a scavenger froth product. The scavenger froth product is thereafter combined with the primary froth product for further treatment. This combined froth product typically contains about 52 percent bitumen, 6 percent mineral ti~3t~,4 matter, 41 percent water, and may contain fro~ 20 to 70 volume percent air. It resembles a liquid foam that is difficult to pump and, for that reason, is usually treated with steam to improve its flow characteristics.
The high water and mineral contents of the combined froth product normal]y are reduced by diluting it with a hydrocarbon diluent such as naptha. It is then centrifuged to produce a tailings product and a final bitumen product that typically contains essentially no water and about 1.3 percent solids and that is suitable for coking, hydrovisbreaking and other refining techniques for producing a synthetic crude oil. The tailings products, containing some naptha, are discarded.
There are basically four effluent streams from the Hot Water Process. Each carries with it some bitumen from the ~eed; thereby reducing the efficiency of the Process. These include the oversize material, the sand from the separation cells, the silt and clay from the scavenger cells and the tailings from the centrifuges.
Up to 30 percent of the bitumen in the original feed and up to 5 percent of the naptha stream may be lost in this manner. Much of this bitumen effluent finds its way into large retention or tailings ponds that are typical of the Hot Water Process. The bottom of such ponds may contain up to 50 percent dispersed mineral matter consisting substantially of clay and silt as well as up to 10 percent bitumen. As disclosed in Canadian Patent No. 975,697 issued on October 7, 1975 to Davitt H. James, this part of the pond contents, referred to as sludge or sediment, is a potential source of bitumen.
The ~lot Water Proce~s described in the preceeding paragraphs separates bitumen ~rom a slurry prepared from mined tar sands. The slurry is hot, contains finely dispersed air bubbles and the bitumen is in the form of small flecks. Such a slurry is amenable to subsequent separation in the Hot Water Process, after dilution with water, wherein bitumen forms into a roth that rises to the top of the bath and is skimmed therefrom. Alkaline reagents such as sodium hydroxide are normally added in this process to give the slurry those properties that provide for efficient flotation of the bitumen in said water. However, in the presence of sodium nydroxide, fine clay particles in the effluent streams deposited into the tailings ponds do not readily settle into a compacted solids layer. For that reason inordinately large settling ponds are required to contain the effluents from commercial hot water tar sands extraction plants.
With some mined tar sands, particularly with Utah tar
2~ sands, the bitumen is so viscous that when a screen is used to remove debris, rocks and oversize lumps from the slurry coming from the conditioning drum, this screen becomes coated with bitumen from the slurry.
The thus coated screen reduces the flow of slurry to the sump and can result in considerable loss of bitumen with the oversize discard material. To overcome this problem inordinately large screens are required for the removal of this gangue material, or in the alternative, the aperture size of this screen must be enlarged. The 33 process of the present invention replaces this screen and eliminates this problem caused by the screen becoming coated or blinded by bitumen. The present invention also removes coarse sand from the slurry.
313~
A tar sand separation process, which may be used as a replacement for the Hot Water Process, has been developed utilizing an oleophilic sieve. This process, called the Kruyer Process, relies upon the ability of an oleophilic sieve to separate hydrophilic material from oleophilic material. It is described in U.S.
patents 4,224,138, 4,23~,995 and 4,392,949, and Canadian patents 1,085,760, 1,129,363, 1,132,373, 1,141,318, 1,141,319 and 1,444,498 all of which have issued to Jan ~ruyer.
The Kruyer Process makes use of an apertured oleophilic sieve to separate bitumen or other liquid hydrocarbons from sand and from other particulate solids in an aqueous medium. In this process, the bitumen and oleophilic solids are normally captured by the oleophilic sieve surfaces while the hydrophilic solids and water pass through the sieve apertures. Prior to separation by the oleophilic sieve, the mixture to be separated is normally screened by an oversize rejection screen or sieve which removes any solids that are too large to pass through the apertures of the oleophilic sieve. When the apertures of the oleophilic sieve are small to efficiently capture the bitumen from the mixture, the apertures of the oversize rejection sieve must also be small. The same problems of blinding of the oversize rejection sieve described above for the Hot Water Process may also occur in this application, only more particularly so, because of the need for the oleophilic sieve to have small apertures for effective capture of the bitumen of the mixture. The present invention not only conveniently removes the coarse solids from the mixture before it reaches the oleophilic sieve but it also removes coarse sand from this mixture. Removal of this coarse sand tends to improve the efficiency of the oleophilic sieve and reduces the abrasion of this oleophilic sieve and causes it to last longer.
The oleophilic sieve may also be used for the recovery of valuable metals and minerals from low grade ores especially when these metals or minerals are present in the ores in the form of very small finely dispersed particles. When this ore is crushed and is mixed with water and is passed through the process of the present invention, the fine mineral and metal particles tend to 1~ stay in suspension in the liquid product of the invention while the coarse gangue particles are removed as the coarse solids product. Minerals or metals may then be recovered conveniently from this liquid product stream through adhesion of these metals or minerals to the oleophilic sieve by passing the liquid product through the oleophilic sieve. Removal of the coarse gangue solids of any mixture, with or without crushing, prior to passing it to the oleophilic sieve for recovery of the metal or mineral values, usually ~3 improves the efficiency of the oleophilic sieve separator and reduces the abrasion of the oleophilic sieve and causes it to last longer.
It is therefore an object of this invention to provide a method of separating coarse, dense, particulate gangue solids from a mixture containing such gangue with water and recoverable mineral values by classification means utilizing a moveable floor contained in an aqueous pool.
It is also an object of this invention to provide a means of gangue removal which does not require the use of oversize removal devices such as screens.
~f;'`~
It is a specific object oE the present invention to remove coarse sand from a mined tar sand ~ixture before processing the tar sand for bitumen recovery.
Another specific object is to remove coarse solids from low grade mined ore or placer deposits to improve the subsequent recovery of metals or minerals from said ore.
A still different object of this invention is to remove coarse solids from an aqueous tar sand slurry to improve subsequent bitumen recovery from said slurry by oleophilic sieve separation.
Yet another object of this invention is to provide a method for removing coarse solids from tailings, middlings or effluents from a Hot Water Process tar sand separation plant to improve the subsequent removal of bitumen from these tailings, middlings or effluents by means of oleophilic separation.
These and other objects may be accomplished by means of an aqueous pool contained by a moving floor which cooperate to classify the mixture into a coarse gangue solids product which is carried away as an underflow from the pool by the moving floor and an aqueous suspension containing recoverable minerals, metals or bitumen that is removed as an overflow from the pool for subsequent treatment. The mixture to be separated enters the pool where gangue settles to become the underflow which is moved out of the pool by the moving floor. Tbe remaining materials stay in suspension and are removed from the pool as a continuous liquid overflow stream.
C~
IN THE DRAWINGS:
Fig. 1 is a side cross sectional view of one embodiment of a classifier of the present invention showing a generally horizontal conical drum.
Fig. 2 is a transverse cross sectional view of the classifier of Fig. 1 showing the contents of the drum through section A-A of Fig. 1.
Fig~ 3 is a side cross sectional view of a second embodiment of a classifier of the present invention showing an inclined conveyor belt.
Fig. 4 is an enlarged sectional view of a broken away section of the top flight of the belt of Fig. 3.
REFERRING NOW TO THE DRAWINGS:
As used in this description "particulate solids" refers to any mixture to be classified into coarse solids or gangue and recoverable minerals. The particulate solids mixture is first admixed with an aqueous liquid to form a slurry and is then classifed.
"Classification" refers to the separation of particulate solids in an aqueous pool into two fractions, referred to as an overflow and an underflow, depending on their rate of settling in an aqueous pool.
"Overflow" refers to that portion of the particulate solids that remain suspended in or floats on the surface of the aqueous pool during classification which suspended particulate solids or floating materials are referred to as "recoverable minerals." nUnderflow"
refers to that portion of the particulate solids that settle to the bottom or floor of the aqueous pool during classification which solids are referred to as "coarse solids" or "ganguen. "Aqueous pool" refers to a pool of water that contains particulate ~olids materials being classified and may contain a floating layer of bitumen. "situmen" refers to a viscous liquid or semi-solid hydrocarbon with a specific gravity between 0.9 and 1.5 that is found in tar sands, oil sands or bituminous sands and having a viscosity that may range between that of conventional heavy oil and heavy tar or asphalt. "Liquid" or "aqueous liquid"
refers to any water that is used in the classification process and may include fresh water, recycle water, process water that contains some suspended particles.
"Recoverable minerals" refers to metals, mineral ore concentrates, silt, clay particles, and bitumen having a particle size and/or density such that such material will either remain temporarily suspended in or float on the surface of an aqueous pool for removal as overflow.
"Coarse solids" and "gangue" refers to coarse sand, gravel, lumps, rocks or any other particulate solids that will settle to the bottom of the aqueous pool as underflow.
The present invention is based upon the fact that coarse gangue solids, such as sand, rocks, gravel, etc., generally settle more quickly in an aqueous pool than less coarse solid recoverable mineral particles, such as silt, clay, or small metallic or mineral particles, and will also settle more quickly than bitumen droplets or tar particles in water. In this manner it is possible to use an aqueous phase to separate recoverable minerals including bitumen, from
The thus coated screen reduces the flow of slurry to the sump and can result in considerable loss of bitumen with the oversize discard material. To overcome this problem inordinately large screens are required for the removal of this gangue material, or in the alternative, the aperture size of this screen must be enlarged. The 33 process of the present invention replaces this screen and eliminates this problem caused by the screen becoming coated or blinded by bitumen. The present invention also removes coarse sand from the slurry.
313~
A tar sand separation process, which may be used as a replacement for the Hot Water Process, has been developed utilizing an oleophilic sieve. This process, called the Kruyer Process, relies upon the ability of an oleophilic sieve to separate hydrophilic material from oleophilic material. It is described in U.S.
patents 4,224,138, 4,23~,995 and 4,392,949, and Canadian patents 1,085,760, 1,129,363, 1,132,373, 1,141,318, 1,141,319 and 1,444,498 all of which have issued to Jan ~ruyer.
The Kruyer Process makes use of an apertured oleophilic sieve to separate bitumen or other liquid hydrocarbons from sand and from other particulate solids in an aqueous medium. In this process, the bitumen and oleophilic solids are normally captured by the oleophilic sieve surfaces while the hydrophilic solids and water pass through the sieve apertures. Prior to separation by the oleophilic sieve, the mixture to be separated is normally screened by an oversize rejection screen or sieve which removes any solids that are too large to pass through the apertures of the oleophilic sieve. When the apertures of the oleophilic sieve are small to efficiently capture the bitumen from the mixture, the apertures of the oversize rejection sieve must also be small. The same problems of blinding of the oversize rejection sieve described above for the Hot Water Process may also occur in this application, only more particularly so, because of the need for the oleophilic sieve to have small apertures for effective capture of the bitumen of the mixture. The present invention not only conveniently removes the coarse solids from the mixture before it reaches the oleophilic sieve but it also removes coarse sand from this mixture. Removal of this coarse sand tends to improve the efficiency of the oleophilic sieve and reduces the abrasion of this oleophilic sieve and causes it to last longer.
The oleophilic sieve may also be used for the recovery of valuable metals and minerals from low grade ores especially when these metals or minerals are present in the ores in the form of very small finely dispersed particles. When this ore is crushed and is mixed with water and is passed through the process of the present invention, the fine mineral and metal particles tend to 1~ stay in suspension in the liquid product of the invention while the coarse gangue particles are removed as the coarse solids product. Minerals or metals may then be recovered conveniently from this liquid product stream through adhesion of these metals or minerals to the oleophilic sieve by passing the liquid product through the oleophilic sieve. Removal of the coarse gangue solids of any mixture, with or without crushing, prior to passing it to the oleophilic sieve for recovery of the metal or mineral values, usually ~3 improves the efficiency of the oleophilic sieve separator and reduces the abrasion of the oleophilic sieve and causes it to last longer.
It is therefore an object of this invention to provide a method of separating coarse, dense, particulate gangue solids from a mixture containing such gangue with water and recoverable mineral values by classification means utilizing a moveable floor contained in an aqueous pool.
It is also an object of this invention to provide a means of gangue removal which does not require the use of oversize removal devices such as screens.
~f;'`~
It is a specific object oE the present invention to remove coarse sand from a mined tar sand ~ixture before processing the tar sand for bitumen recovery.
Another specific object is to remove coarse solids from low grade mined ore or placer deposits to improve the subsequent recovery of metals or minerals from said ore.
A still different object of this invention is to remove coarse solids from an aqueous tar sand slurry to improve subsequent bitumen recovery from said slurry by oleophilic sieve separation.
Yet another object of this invention is to provide a method for removing coarse solids from tailings, middlings or effluents from a Hot Water Process tar sand separation plant to improve the subsequent removal of bitumen from these tailings, middlings or effluents by means of oleophilic separation.
These and other objects may be accomplished by means of an aqueous pool contained by a moving floor which cooperate to classify the mixture into a coarse gangue solids product which is carried away as an underflow from the pool by the moving floor and an aqueous suspension containing recoverable minerals, metals or bitumen that is removed as an overflow from the pool for subsequent treatment. The mixture to be separated enters the pool where gangue settles to become the underflow which is moved out of the pool by the moving floor. Tbe remaining materials stay in suspension and are removed from the pool as a continuous liquid overflow stream.
C~
IN THE DRAWINGS:
Fig. 1 is a side cross sectional view of one embodiment of a classifier of the present invention showing a generally horizontal conical drum.
Fig. 2 is a transverse cross sectional view of the classifier of Fig. 1 showing the contents of the drum through section A-A of Fig. 1.
Fig~ 3 is a side cross sectional view of a second embodiment of a classifier of the present invention showing an inclined conveyor belt.
Fig. 4 is an enlarged sectional view of a broken away section of the top flight of the belt of Fig. 3.
REFERRING NOW TO THE DRAWINGS:
As used in this description "particulate solids" refers to any mixture to be classified into coarse solids or gangue and recoverable minerals. The particulate solids mixture is first admixed with an aqueous liquid to form a slurry and is then classifed.
"Classification" refers to the separation of particulate solids in an aqueous pool into two fractions, referred to as an overflow and an underflow, depending on their rate of settling in an aqueous pool.
"Overflow" refers to that portion of the particulate solids that remain suspended in or floats on the surface of the aqueous pool during classification which suspended particulate solids or floating materials are referred to as "recoverable minerals." nUnderflow"
refers to that portion of the particulate solids that settle to the bottom or floor of the aqueous pool during classification which solids are referred to as "coarse solids" or "ganguen. "Aqueous pool" refers to a pool of water that contains particulate ~olids materials being classified and may contain a floating layer of bitumen. "situmen" refers to a viscous liquid or semi-solid hydrocarbon with a specific gravity between 0.9 and 1.5 that is found in tar sands, oil sands or bituminous sands and having a viscosity that may range between that of conventional heavy oil and heavy tar or asphalt. "Liquid" or "aqueous liquid"
refers to any water that is used in the classification process and may include fresh water, recycle water, process water that contains some suspended particles.
"Recoverable minerals" refers to metals, mineral ore concentrates, silt, clay particles, and bitumen having a particle size and/or density such that such material will either remain temporarily suspended in or float on the surface of an aqueous pool for removal as overflow.
"Coarse solids" and "gangue" refers to coarse sand, gravel, lumps, rocks or any other particulate solids that will settle to the bottom of the aqueous pool as underflow.
The present invention is based upon the fact that coarse gangue solids, such as sand, rocks, gravel, etc., generally settle more quickly in an aqueous pool than less coarse solid recoverable mineral particles, such as silt, clay, or small metallic or mineral particles, and will also settle more quickly than bitumen droplets or tar particles in water. In this manner it is possible to use an aqueous phase to separate recoverable minerals including bitumen, from
3~ coarse gangue solids on a continuous basis in a pool of aqueous phase, provided that the coarse gangue solids are continuously removed from this pool as an underflow after they have settled to the floor of the pool, and that the recoverable minerals axe removed from this pool on a continuous basis in a stream of liquid overflow. Removal of the underflow from the pool is l~ti~3~)~"~
achieved by providing a moving floor to the pool to carry the coarse gangue solids that have settled to the surface of this floor out of the pool. Removal of the overflow is achieved by a continuous flow of liquid out of the pool.
Two separate embodiments of the invention are disclosed. In one embodiment the pool is formed on the flight of an inclined conveyor belt. The top flight of the conveyor belt is either troughed to form a pool or the belt is provided with sides to contain the pool.
The aqueous particulate solids mixture to be separated flows into this pool from one or more pipes or chutes and flows down the incline of the conveyor flight while the coarse gangue solids settle to the bottom of the pool towards the surface of the conveyor belt as an underflow. The conveyor belt is kept in motion and moves up the incline so that the underflow is carried up the incline and then falls off the conveyor as it passes the conveyor endroll at the top of the conveyor incline. The overflow, containing recoverable minerals, flows down the conveyor belt decline and falls off the conveyor at the conveyor endroll at the bottom of the decline. In this manner the classification and separation between underflow and overflow is achieved in an aqueous pool on a moving inclined conveyor belt. Optimum separation can be achieved by suitably changing the incline of the conveyor and/or changing the speed of movement of the conveyor belt.
A stream of water may be used to wash the underflow before these leave the conveyor flight to remove retained overflow out of the underflow. This stream of water may be supplied from one or more pipes or chutes that are located higher up the incline than the pipes or chutes that supply particulate solids mixture for ~i'3 1~
the separation to the conveyor. Small riEfles may be molded or attached to the floor o~ the conveyor belt to capture the settled underflow for transport uphill by the conveyor, or the conveyor belt floor may be textured or made rough for that same purpose.
Conventionally, sluice boxes are used to classify particulate placer or ore deposits into two fractions depending upon their rates of settling through water.
Gold particulates, for example, are denser than sand or rock particles, and/ if large enough, will settle to the bottom of the sluice box more readily than the sand or rock particles. The sand and rock particles are washed through the sluice box as overflow while the gold particles settle and remain between the riffles on the sluice box floor. However, when the gold particles of an ore or placer deposit are very small, they do not settle very rapidly in the sluice box but are washed out of the sluice box with the stream of water intended for the overflow. The process of the present invention serves to act as a sluice box in reverse where very small particles, for example gold, remain suspended in the water and flow out of the classification apparatus as overflow while the coarse sand and rock particles settle to the bottom of the apparatus as underflow. In the same manner, bitumen flows out of the apparatus away from the coarse sand and rocks when separating tar sand. In the present invention these coarse gangue solids are removed as an underflow from the apparatus by the conveyor belt floor of the classification apparatus which moves up the incline in a direction opposite to the overflow which is down the incline through the apparatus.
In the second embodiment of the invention, the classification pool is formed inside a generally horizontal rotating tumbler or drum. The inside of this drum consists of a forward conical section and a rear cylindrical section. The cylindrical section attaches to the large diameter end of the conical section and has generally the same diameter as that portion of the conical section, but may also have a diameter that is larger than that. The particulate solids mixture for classification enters the drum at the small diameter end of the conical section as a slurry into an aqueous pool that is contained in the drum by one or more endwalls thereof. Aqueous overflow liquid with suspended recoverable metal, mineral or bitumen values flows out of the drum through the endwall of the cylindrical portion of the drum. Due to the force oE gravity and the centrifugal force and the tumbling of the drum, the coarse gangue solids settle in the conical section of the drum as overflow, flow along the bottom wall thereoE from the small diameter end to the large diameter end and into the cylindrical section of the drum. The rate of rotation of this drum is controlled such that the centrifugal forces on the underflow solids adjacent to drum wall at the cylindrical portion of the drum are large enough to carry these solids out of the pool by the cylindrical drum wall and deposit them onto a conveyor or chute for removal. Such a conveyor or chute is mounted through the endwall of the cylindrical drum section partly into the drum to permit transport of the underflow, caught by this conveyor or chute, out of the drum.
The illustrated embodiments will now be described with reference to the drawings.
Fig. 1 illustrates the rotating drum classifier embodiment of the invention. The classifier consists of a generally horizontal conLcal drum 1 supported on t~i4 bearings or on hoops 4, 5 which rest on rollers 20 so as to permit tumbling oE drum 1 at any desired rate. A
motor and drive (not shown) provide the rotative power.
Drum 1 is made up of a forward conical section 2 and a rear cylindrical section 3. Front endwall 6 and rear endwall 7 partially close off the ends of the drum leaving central openings 9 and 17 to a allow for the introduction and removal of particulate solids materials to and from the drum. Forwardly extending baffles 14 may be mounted in the cylindrical portion of the drum, if desired, to assist in its operation. A
conveyor, consisting of conveyor endrolls 15, a conveyor belt 16 and a motor and drive (not shown) is partly inserted through outlet 17 in the rear endwall 7 of the drum 1. A liquid receiver 18 is mounted under the outlet 17 of the rear endwall 7 to collect overflow leaving the drum. A chute or partition 19 is mounted under the conveyor beyond the rear endwall 7 to catch the underflow material conveyed out of the drum by the conveyor belt 16.
Fig. 2 is a transverse view of the drum of Fig. 1 seen through section A-A of Fig. 1. In addition to the described items this view also shows a baffle 29 and a supply pipe 32 for wash water 31 that is used for washing overflow metals, minerals or bitumen out of the underflow portion of the mixture. The view also illustrates the approximate flow of solids and liquid inside the cylindrical portion of the drum.
The operation of the rotating drum classifier may now be described with reference to Fig. 1 and 2.
Particulate solids mixture 10 to be classified enters as an aqueous slurry through opening 9 in the front wall of the conical section through one or more feed pipes 8 into the drum interior where it establishes ~ .
and/or adds to an a~ueous pool 12 ha~ing a liquid leve1 21 th~t is maintained by the outlet 17 in the rear wall 7 of the drum. The drum revolves at a rate between 50~ and 120~ of the critical rotation r~te which is defined as RPM = ~2936/r] ......... (1) in revolutions per minute where r is the drum inner radius in feet of the cylindrical section 3 of the drum 1. The centrifugal orce and the force of gravity at the apex of the inside wall of the cylindrical section of the drum are equal and opposite at the critical rotation rate. When the drum rotation rates begins to exceed the critical rotation rate, underflow from the mixture will commence to attach itself to the drum inside wall at the cylindrical portion of the drum. As the rate of rotation is increased beyond that, a progressively thicker layer of underflow will remain attached to the drum wall. However, in those locations in the drum that have a small cross section, and hence a small radius of rotation, such as in the conical portion 2 of the drum or in the layers of underflow in the cylindrical portion 3 that are not immediately adjacent to the interior drum wall, the underflow particles will only be carried along by the revolving drum wall for a distance before they fall back into the drum interior. Large lumps and rocks and gravel in the cylindrical portion 3 of the drum have a center of gravity that is some distance away from the drum wall.
This gives them a smaller radius of curvature than small particles such as sand which can travel closer to the drum wall. For this reason rocks and other coarse particles fall back into the drum interior soon after they are carried out of the li~uid level 21 of the drum mixture unless baffles 14 are used to lift them higher.
The particulate solids mixture 10 to be separated enters drum 1 via drum inlet 9 at the small end ~ of its conical portion 2 through opening 9 and classifies into an underflow layer 11 that settles to the inside drum wall and moves toward and into the cylindrical portion 3 while the finer or small particles and/or bitumen remain in suspension as overflow in aqueous pool 12. Some or all of the bitumen may float to the top.
The forces that induce classification of the coarse solids may be approximated by:
F = M.g. cos o + A.M.g.r. (RPM) ....... (2) where F is the force on the particle in dynes causing this particle to flow towards the drum wall, M is the buoyed mass of the particle in grams, g is a gravitational conversion factor, A is a conversion constant, r is the radius of curvature in meters of the particle moving through the drum, RPM is the value of rotation of the drum and O is the angle (30) enclosed in Fig. 2 between a line drawn from the center of the drum vertically downward and a line drawn from the center of the drum to the particle under consideration.
The forces that oppose classification of the solids in the drum are the shear or drag forces on the particles as they flow in the aqueous pool in the drum. These drag forces are a function of the surface area of the settling particle. The net effect is that dense, large, particles settle more rapidly in the liquid in the drum than light, small, particles. Generally, for the mixtures that will be classified in the drum, the coarse solids of the mixture settle to the wall of the drum as underflow and leave the metal or mineral values ;9()~i4 in suspension as overflow. Some overflow particles, though denser than the coarse underflow solids, are small enough in size that they will not readily settle to the drum wall in the tumbling mixture in the drum.
In the case of bitumen or tar, these are light enough S that they will not settle to the drum wall but remain suspended in the aqueous pool in the drum or float on top of this pool.
Overflow liquid 13 flowing out of the drum through its rear wall 7 carries the metal, mineral and bitumen values out of the drum. The underflow 11 collected at the inside wall of the cylindrical portion 3 are carried out of the aqueous pool by this wall under the combined gravity and centrifugal forces. When the underflow is finally carried high enough that it falls down from the drum wall, it falls onto the conveyor flight 16 which carries the underflow 11 out of the drum for disposal.
The flow of the liquid and of the solids in the drum 1 may be illustrated in further detail with reference to Fig. 2. The aqueous pool 12 in the drum 1 has a constant level 21 dictated by opening 17. Underflow 11 settles in pool 12 as described. In the cylindrical portion 3 of the drum, the drum wall is roughened, textured or provided with riffles to give the underflow 11 a suitable surface to attach to after settling.
Baffles 14 may further be provided at this wall to lift rocks, lumps and gravel 13 out of the aqueous pool.
Under the influence of the centrifugal force this drum wall carries both some liquid 22 and underflow 11 up along the drum wall in the direction of rotation.
Howevar, the underflow solids 11 are closer to the drum wall than the carried up liquid 22 and hence are influenced to a larger degree by this centrifugal force .~
~ 3~
than the liquid. As a consequence of the interaction oE the force of gravity with the centrifugal force in the drum, the li~uid 22 generally falls back into the drum interior before the underflow 11 and hence underflow is carried up higher before it falls back down. By control of ~he drum rotation rate, at least a portion of the carried up underflow 11 is delivered onto the conveyor belt 16 for removal out of the drum for disposal. Wash water 31 may be added to the drum 1 through a one or more pipes 32 at a suitable location to wash bitumen or metal or mineral values out of the underflow 11 before they are deposited onto the conveyor belt 16. A baffle 29 may be inserted in the interior of the drum 1 to separate floating bitumen from wash water 31 or from underflow settling in the drum. Due to the effect of the radius of curvature on the centrifugal force in the drum, (see equations 1 and 2) in the conical portion (2) of the drum, the underflow 11 will be lifted above the aqueous pool 12 surface 21 to a lesser degree than in the cylindrical portion 3. This allows the mixture in the drum time for several drum rotations in order to classify the mixture into underflow solids and into an aqueous overflow suspension. These underflow solids 11 are moved axially towards the cylindrical portion 3 before they are finally lifted out of the liquid and deposited onto the conveyor belt 16 for removal.
The aqueous overflow suspension containing the metal, mineral and/or bitumen values flow out of the cylindrical portion of the drum through opening 17 in the rear wall 7 of the drum into container 18 as the product 13 of the classification. This product 13 may then be withdrawn via hopper 18 for treatment in the oleophilic sieve separation process.
3t3~
The drum classiEier is here described a~ having a conical portion and a cylindrical portion. However, it is also possible to use a mechanically constructed drum structure that only has a conical portion. When such a drum is used for classification, the centrifugal forces on the particles adjacent to the inside wall at the large end o~ the conical drum, and the adhesive forces existing between the coarse particles and the drum wall will, for all practical purposes, collect coarse solids in the large diameter end of the drum and establish a cylindrical inside surface for some small distance adjacent to the rear end wall that will remain there permanently during operation. Therefore, the cylindrical portion here described is either part of the construction of the drum or it establishes itself by forming a bed of solids at the inside wall at the large diameter end of the conical drum during operation of the drum classifier.
The small end of the conical portion 2 may contain an end wall 6 with a central opening 9. Alternatively, the central inlet opening 9 may be formed by the truncated end of the conical section 2 without an end wall 6.
For a commercial classifier the concepts here described will work for a very small drum and will also work for a very large drum provided that the drum speed is adjusted accordingly to operate between 50% to 120~ of the critical speed defined above. Therefore, drum classifiers may be used having diameters from l foot to 50 feet or larger at the large end, 0.1 to lO feet or larger at the small end and l.0 to 50 feet or longer in length.
Several of these drum classifiers may be mounted in series; either to improve the overflow metal, mineral or bitumen removal out of tùe underflow or to improve : .
~t;9~3~
the remova1 oE underflow out o~ the overflow liquid product.
Metal or mineral solids that may be classified from the coarse particulate solids mixtures in the instant invention as overflow may vary considerably in size but preferably are smaller than 100 microns in size and more preferably smaller than 50 microns.
Fig. 3 illustrates the inclined belt classifier embodiment of the present invention. It consists of a generally inclined conveyor belt 34 supported by two conveyor endrollers 33 that are driven by a motor and a drive (not shown). Normally one of the conveyor rollers is driven and the other idles. The conveyor belt 34 may be troughed at the top flight by the use of appropriate training rollers (not shown) to permit liquid on this flight to form an aqueous pool. In the alternative, flexible sides 35 may be molded or attached to the conveyor belt for that purpose. The conveyor revolves such that the top flight moves up the incline at all times. Particulate solids mixture 10 to be classified flows onto the top flight surface 37 and forms an aqueous pool 12 that flows down the inclined of the conveyor belt 34. By way of illustration the top flight is broken away and enlarged in Fig. 4 to illustrate this pool. Underflow solids 11 fro~ the mixture that may contain rocks, lumps and other coarse particles settle to the bottom of the pool and onto the floor of the top belt flight 37 wnich may be textured, roughened or which may be provided with riffles (not shown) to hold these solids there. The aqueous pool portion 13 that contains suspended solids, such as metal and mineral values and other fine particulate matter, and/or bitumen flows down the belt incline to fall off the conveyor near the bottom endroll into a 3t)~
liquid receiver 18 as the product 13 of the classification. This liquid product 13 i5 then conveyed, pumped or transported via drain 27 to subsequent processing to remove the metal, mineral or bitumen values from the water and from the other suspended solids. The coarse underflow solids 11 of the mixture, that have settled to the floor 37 of the top flight are carried up the incline of the moving conveyor 34 and fall off the conveyor as they pass the top conveyor endroll and fall onto a chute or trough 40 for disposal. The coarse solids are normally discarded as gangue but after disposal, water drained from this gangue may be reused in the process where suitable.
Baffles 36 are provided to contain the liquid during separation and a s-tream of wash water 31 from one or more wash water pipes 32 may be used to wash metal or mineral or bitumen overflow values out of the coarse underflow solids 11 before these solids leave the conveyor for recovery.
Thus, in both embodiments described, a pool of aqueous liquid is used to classify an aqueous particulate solids mixture into a coarse underflow solids product and a liquid overflow product that contains suspended metal, mineral and/or bitumen values along with other suspended solids and/or that has bitumen floating on top of the overflow. The aqueous pool is contained by a moving floor that carries the settled underflow and lifts it overhead out of the pool and a wash water stream may be used to wash this underflow before it lea~es the classification apparatus. This wash water becomes part of the aqueous pool. The process is continuous with particulate solids mixture continuously entering the aqueous pool and underflow continuously being carried out of the pool. Overflow continuously Elows out of the pool Eor subsequent treatment as the desired product.
A placer deposit that con-tains one ounce of gold for every 21 tons of ore is classified by the process of the instant invention to recover the gold values.
Hydraulic jets of water are used to loosen and suspend the ore and a slurry pump is used to hydraulically convey the suspension mixture thus produced to the drum classifier of the instant invention.
The drum is 5 feet long, the conical section has a minimum diameter of 0.5 feet and a maximum diameter of 5 feet and is 4.5 feet long. The cylindrical portion of the drum is 5 feet in diameter, 0.5 feet long and is welded to the large end of the conical section. The cylindrical portion is closed off with an endwall that has a 2.0 feet diameter central hole for liquid outlet.
A 4 feet long, 1.0 foot wide, conveyor protrudes 2.0 feet into the interior of the drum through the central hole in the rear drum endwall and moves at a belt speed of 2 feet per second. The drum revolves near the critical rotation rate, which is defined as ~2936/r]
in revolutions per minute where r is the maximum inside drum radius in feet. For the drum of this example, this is approximately 34 RPM or about one drum revolution every 2 seconds.
3~ Thirty tons per hour of placer deposit slurry, composed of approximately 50% solids and 50% water by weight, are pumped to the drum for processing. This produces, by classification in the drum, 18 tons of coarse solids product per hour that contains 70% solids and 30% water and also contains one ounce of gold for every 225 tons of coarse solids product. Five tons per hour of wash t)~
water are introduced simultaneously into the same drum to wash gold values out oE the coarse solids before these leave the drum via the conveyor as underflow. A
total liquid product of 17 tons per hour leaves the drum through the central hole in the rear drum wall.
The liquid overflow product is composed of 86% water and 14% suspended solids. This product contains one ounce of gold for every 27 tons of liquid product. The liquid overflow is piped thereaf-ter to an oleophilic sieve separator where it is mixed with bitumen to permit capture of the gold values by the oleophilic sieve while most of the water and suspended gangue particles pass through the apertures of the oleophilic sieve. The gold values are thereafter recovered from the oleophilic sieve as a bitumen and gold product after which the gold is recovered by burning this product in a metallurgical oven with suitable slagging reagents to produce pure gold and slag that are easily separated thereafter.
EXAMPLE II
Tailings from an Alberta (Canada) hot water extraction mined tar sands plant are desanded by the inclined belt classifier as described above. The classifier is used as a pilot plant unit for desanding 10 tons per hour of tailings that contain 64% solids, 35% water and 1.0%
bitumen by weight which are pumped to the belt classifier. A total of 6.32 tons per hour of coarse solids product is produced by the belt classifier that contains 71.2% solids, 28.5% water and 0.3% bitumen and is disposed off into the tailings pond of the commercial tar sands plant. Simultaneously with the tailings, 5 tons of water per hour are introduced from the top of the same tailings pond through a pipe into the belt classifier to wash bitumen values out of the coarse solids product before this leaves the belt for ;90~
disposal as underflow. A total of 8.68 tons per hour o liquid overflow product leaves the classifier and is pumped to an oleophilic sieve separator to recover the bitumen. This liquid product stream con~ains 23.0~
solids 76.0% water and 1.0% bitumen. During subsequent separation by the oleophilic sieve separator of this liquid streaml the water and hydrophilic solids pass through the apertures of the oleophilic sieve while the bitumen is captured by the sieve and is recovered as the bitumen product. An equivalent of 0.06 tons per hour of pure bitumen are produced by the oleophilic sieve separator.
EXAMPLE III
Mined tar sands from the Asphalt Ridge, Utah deposit are separated in a pilot plant by mining the tar sand, conditioning it in a mulling or conditioning drum with steam and water to produce a tar sand slurry, classifying this slurry in a drum classifier as described in Example I above to remove coarse solids and coarse sand from the slurry, and then separating the liquid product of this drum classifier by an oleophilic sieve separator to recover the bitumen while discarding the other minerals.
In this pilot plant 10 tons per hour of mined tar sands containing 90% solids, 9~ bitumen and 1~ water by weight, are mixed with 5 tons of water and steam in the conditioning drum to produce 15 tons of tar sand slurry at a temperature of 80 degrees C. This slurry or mixture is introduced into the drum classifier of Example I through a feed pipe that introduces the slurry through the small end of the conical drum portion into the classifier. The drum revolves at 0.5 revolutions per second or 30 RPM. A stream of recycle wash water of 5 tons per hour at 45 degrees C. is : ' ~;9S3~,4 introduced through a pipe through the central opening o the rear drum wall and i9 directed into the classifier so that it will wash bitumen out of t.he solids accumlating at the drum wall in the cylindrical portion of the classifier. A total of 10.02 tons per hour of coarse solids product leave the classifier via the conveyor belt as underflow consisting of 79.8%
solids, 20.0~ water, and 0.2% bitumen by weight. The classifier produces 9.98 tons of liquid product that spills out of the central opening of the rear drum wall as overflow consisting of 10.0% solids, 81.2% water and 8.8~ bitumen. This liquid product is pumped to an oleophilic sieve separator which recovers a bitumen product that has a pure bitumen content equivalent to 0.85 tons of pure bitumen per hour.
Although the invention as has been described is deemed to be that which forms the preferred embodiments thereof, it is recognized that departures may be made therefrom and still be within the scope of the invention which is not to be limited to the details disclosed but is to be accorded the full scope of the claims so as to include any and all equivalent methods.
For example, after the liquid product leaves the classifiers of the instant invention it may be convenient to hydraulically transport this liquid through a pipe or pipe line for subsequent processing or separation and there may be an advantage to decant off some of the water from this liquid product before it is transported hydraulically for any long distances.
This decanted water may then be reused in the process of the invention as required. Such refinements will tend to improve further the economic merit of this invention for processing ores or for recovering bitumen from mined tar sands or from other mixtures.
., :
The process is useful to remove coarse solids from almost any low grade ore provided that the metal, mineral or bitumen values of the ore are of a density or par-ticles size that causes these values to settle in water less readily than the coarse gangue particles of the ore.
. ~ -
achieved by providing a moving floor to the pool to carry the coarse gangue solids that have settled to the surface of this floor out of the pool. Removal of the overflow is achieved by a continuous flow of liquid out of the pool.
Two separate embodiments of the invention are disclosed. In one embodiment the pool is formed on the flight of an inclined conveyor belt. The top flight of the conveyor belt is either troughed to form a pool or the belt is provided with sides to contain the pool.
The aqueous particulate solids mixture to be separated flows into this pool from one or more pipes or chutes and flows down the incline of the conveyor flight while the coarse gangue solids settle to the bottom of the pool towards the surface of the conveyor belt as an underflow. The conveyor belt is kept in motion and moves up the incline so that the underflow is carried up the incline and then falls off the conveyor as it passes the conveyor endroll at the top of the conveyor incline. The overflow, containing recoverable minerals, flows down the conveyor belt decline and falls off the conveyor at the conveyor endroll at the bottom of the decline. In this manner the classification and separation between underflow and overflow is achieved in an aqueous pool on a moving inclined conveyor belt. Optimum separation can be achieved by suitably changing the incline of the conveyor and/or changing the speed of movement of the conveyor belt.
A stream of water may be used to wash the underflow before these leave the conveyor flight to remove retained overflow out of the underflow. This stream of water may be supplied from one or more pipes or chutes that are located higher up the incline than the pipes or chutes that supply particulate solids mixture for ~i'3 1~
the separation to the conveyor. Small riEfles may be molded or attached to the floor o~ the conveyor belt to capture the settled underflow for transport uphill by the conveyor, or the conveyor belt floor may be textured or made rough for that same purpose.
Conventionally, sluice boxes are used to classify particulate placer or ore deposits into two fractions depending upon their rates of settling through water.
Gold particulates, for example, are denser than sand or rock particles, and/ if large enough, will settle to the bottom of the sluice box more readily than the sand or rock particles. The sand and rock particles are washed through the sluice box as overflow while the gold particles settle and remain between the riffles on the sluice box floor. However, when the gold particles of an ore or placer deposit are very small, they do not settle very rapidly in the sluice box but are washed out of the sluice box with the stream of water intended for the overflow. The process of the present invention serves to act as a sluice box in reverse where very small particles, for example gold, remain suspended in the water and flow out of the classification apparatus as overflow while the coarse sand and rock particles settle to the bottom of the apparatus as underflow. In the same manner, bitumen flows out of the apparatus away from the coarse sand and rocks when separating tar sand. In the present invention these coarse gangue solids are removed as an underflow from the apparatus by the conveyor belt floor of the classification apparatus which moves up the incline in a direction opposite to the overflow which is down the incline through the apparatus.
In the second embodiment of the invention, the classification pool is formed inside a generally horizontal rotating tumbler or drum. The inside of this drum consists of a forward conical section and a rear cylindrical section. The cylindrical section attaches to the large diameter end of the conical section and has generally the same diameter as that portion of the conical section, but may also have a diameter that is larger than that. The particulate solids mixture for classification enters the drum at the small diameter end of the conical section as a slurry into an aqueous pool that is contained in the drum by one or more endwalls thereof. Aqueous overflow liquid with suspended recoverable metal, mineral or bitumen values flows out of the drum through the endwall of the cylindrical portion of the drum. Due to the force oE gravity and the centrifugal force and the tumbling of the drum, the coarse gangue solids settle in the conical section of the drum as overflow, flow along the bottom wall thereoE from the small diameter end to the large diameter end and into the cylindrical section of the drum. The rate of rotation of this drum is controlled such that the centrifugal forces on the underflow solids adjacent to drum wall at the cylindrical portion of the drum are large enough to carry these solids out of the pool by the cylindrical drum wall and deposit them onto a conveyor or chute for removal. Such a conveyor or chute is mounted through the endwall of the cylindrical drum section partly into the drum to permit transport of the underflow, caught by this conveyor or chute, out of the drum.
The illustrated embodiments will now be described with reference to the drawings.
Fig. 1 illustrates the rotating drum classifier embodiment of the invention. The classifier consists of a generally horizontal conLcal drum 1 supported on t~i4 bearings or on hoops 4, 5 which rest on rollers 20 so as to permit tumbling oE drum 1 at any desired rate. A
motor and drive (not shown) provide the rotative power.
Drum 1 is made up of a forward conical section 2 and a rear cylindrical section 3. Front endwall 6 and rear endwall 7 partially close off the ends of the drum leaving central openings 9 and 17 to a allow for the introduction and removal of particulate solids materials to and from the drum. Forwardly extending baffles 14 may be mounted in the cylindrical portion of the drum, if desired, to assist in its operation. A
conveyor, consisting of conveyor endrolls 15, a conveyor belt 16 and a motor and drive (not shown) is partly inserted through outlet 17 in the rear endwall 7 of the drum 1. A liquid receiver 18 is mounted under the outlet 17 of the rear endwall 7 to collect overflow leaving the drum. A chute or partition 19 is mounted under the conveyor beyond the rear endwall 7 to catch the underflow material conveyed out of the drum by the conveyor belt 16.
Fig. 2 is a transverse view of the drum of Fig. 1 seen through section A-A of Fig. 1. In addition to the described items this view also shows a baffle 29 and a supply pipe 32 for wash water 31 that is used for washing overflow metals, minerals or bitumen out of the underflow portion of the mixture. The view also illustrates the approximate flow of solids and liquid inside the cylindrical portion of the drum.
The operation of the rotating drum classifier may now be described with reference to Fig. 1 and 2.
Particulate solids mixture 10 to be classified enters as an aqueous slurry through opening 9 in the front wall of the conical section through one or more feed pipes 8 into the drum interior where it establishes ~ .
and/or adds to an a~ueous pool 12 ha~ing a liquid leve1 21 th~t is maintained by the outlet 17 in the rear wall 7 of the drum. The drum revolves at a rate between 50~ and 120~ of the critical rotation r~te which is defined as RPM = ~2936/r] ......... (1) in revolutions per minute where r is the drum inner radius in feet of the cylindrical section 3 of the drum 1. The centrifugal orce and the force of gravity at the apex of the inside wall of the cylindrical section of the drum are equal and opposite at the critical rotation rate. When the drum rotation rates begins to exceed the critical rotation rate, underflow from the mixture will commence to attach itself to the drum inside wall at the cylindrical portion of the drum. As the rate of rotation is increased beyond that, a progressively thicker layer of underflow will remain attached to the drum wall. However, in those locations in the drum that have a small cross section, and hence a small radius of rotation, such as in the conical portion 2 of the drum or in the layers of underflow in the cylindrical portion 3 that are not immediately adjacent to the interior drum wall, the underflow particles will only be carried along by the revolving drum wall for a distance before they fall back into the drum interior. Large lumps and rocks and gravel in the cylindrical portion 3 of the drum have a center of gravity that is some distance away from the drum wall.
This gives them a smaller radius of curvature than small particles such as sand which can travel closer to the drum wall. For this reason rocks and other coarse particles fall back into the drum interior soon after they are carried out of the li~uid level 21 of the drum mixture unless baffles 14 are used to lift them higher.
The particulate solids mixture 10 to be separated enters drum 1 via drum inlet 9 at the small end ~ of its conical portion 2 through opening 9 and classifies into an underflow layer 11 that settles to the inside drum wall and moves toward and into the cylindrical portion 3 while the finer or small particles and/or bitumen remain in suspension as overflow in aqueous pool 12. Some or all of the bitumen may float to the top.
The forces that induce classification of the coarse solids may be approximated by:
F = M.g. cos o + A.M.g.r. (RPM) ....... (2) where F is the force on the particle in dynes causing this particle to flow towards the drum wall, M is the buoyed mass of the particle in grams, g is a gravitational conversion factor, A is a conversion constant, r is the radius of curvature in meters of the particle moving through the drum, RPM is the value of rotation of the drum and O is the angle (30) enclosed in Fig. 2 between a line drawn from the center of the drum vertically downward and a line drawn from the center of the drum to the particle under consideration.
The forces that oppose classification of the solids in the drum are the shear or drag forces on the particles as they flow in the aqueous pool in the drum. These drag forces are a function of the surface area of the settling particle. The net effect is that dense, large, particles settle more rapidly in the liquid in the drum than light, small, particles. Generally, for the mixtures that will be classified in the drum, the coarse solids of the mixture settle to the wall of the drum as underflow and leave the metal or mineral values ;9()~i4 in suspension as overflow. Some overflow particles, though denser than the coarse underflow solids, are small enough in size that they will not readily settle to the drum wall in the tumbling mixture in the drum.
In the case of bitumen or tar, these are light enough S that they will not settle to the drum wall but remain suspended in the aqueous pool in the drum or float on top of this pool.
Overflow liquid 13 flowing out of the drum through its rear wall 7 carries the metal, mineral and bitumen values out of the drum. The underflow 11 collected at the inside wall of the cylindrical portion 3 are carried out of the aqueous pool by this wall under the combined gravity and centrifugal forces. When the underflow is finally carried high enough that it falls down from the drum wall, it falls onto the conveyor flight 16 which carries the underflow 11 out of the drum for disposal.
The flow of the liquid and of the solids in the drum 1 may be illustrated in further detail with reference to Fig. 2. The aqueous pool 12 in the drum 1 has a constant level 21 dictated by opening 17. Underflow 11 settles in pool 12 as described. In the cylindrical portion 3 of the drum, the drum wall is roughened, textured or provided with riffles to give the underflow 11 a suitable surface to attach to after settling.
Baffles 14 may further be provided at this wall to lift rocks, lumps and gravel 13 out of the aqueous pool.
Under the influence of the centrifugal force this drum wall carries both some liquid 22 and underflow 11 up along the drum wall in the direction of rotation.
Howevar, the underflow solids 11 are closer to the drum wall than the carried up liquid 22 and hence are influenced to a larger degree by this centrifugal force .~
~ 3~
than the liquid. As a consequence of the interaction oE the force of gravity with the centrifugal force in the drum, the li~uid 22 generally falls back into the drum interior before the underflow 11 and hence underflow is carried up higher before it falls back down. By control of ~he drum rotation rate, at least a portion of the carried up underflow 11 is delivered onto the conveyor belt 16 for removal out of the drum for disposal. Wash water 31 may be added to the drum 1 through a one or more pipes 32 at a suitable location to wash bitumen or metal or mineral values out of the underflow 11 before they are deposited onto the conveyor belt 16. A baffle 29 may be inserted in the interior of the drum 1 to separate floating bitumen from wash water 31 or from underflow settling in the drum. Due to the effect of the radius of curvature on the centrifugal force in the drum, (see equations 1 and 2) in the conical portion (2) of the drum, the underflow 11 will be lifted above the aqueous pool 12 surface 21 to a lesser degree than in the cylindrical portion 3. This allows the mixture in the drum time for several drum rotations in order to classify the mixture into underflow solids and into an aqueous overflow suspension. These underflow solids 11 are moved axially towards the cylindrical portion 3 before they are finally lifted out of the liquid and deposited onto the conveyor belt 16 for removal.
The aqueous overflow suspension containing the metal, mineral and/or bitumen values flow out of the cylindrical portion of the drum through opening 17 in the rear wall 7 of the drum into container 18 as the product 13 of the classification. This product 13 may then be withdrawn via hopper 18 for treatment in the oleophilic sieve separation process.
3t3~
The drum classiEier is here described a~ having a conical portion and a cylindrical portion. However, it is also possible to use a mechanically constructed drum structure that only has a conical portion. When such a drum is used for classification, the centrifugal forces on the particles adjacent to the inside wall at the large end o~ the conical drum, and the adhesive forces existing between the coarse particles and the drum wall will, for all practical purposes, collect coarse solids in the large diameter end of the drum and establish a cylindrical inside surface for some small distance adjacent to the rear end wall that will remain there permanently during operation. Therefore, the cylindrical portion here described is either part of the construction of the drum or it establishes itself by forming a bed of solids at the inside wall at the large diameter end of the conical drum during operation of the drum classifier.
The small end of the conical portion 2 may contain an end wall 6 with a central opening 9. Alternatively, the central inlet opening 9 may be formed by the truncated end of the conical section 2 without an end wall 6.
For a commercial classifier the concepts here described will work for a very small drum and will also work for a very large drum provided that the drum speed is adjusted accordingly to operate between 50% to 120~ of the critical speed defined above. Therefore, drum classifiers may be used having diameters from l foot to 50 feet or larger at the large end, 0.1 to lO feet or larger at the small end and l.0 to 50 feet or longer in length.
Several of these drum classifiers may be mounted in series; either to improve the overflow metal, mineral or bitumen removal out of tùe underflow or to improve : .
~t;9~3~
the remova1 oE underflow out o~ the overflow liquid product.
Metal or mineral solids that may be classified from the coarse particulate solids mixtures in the instant invention as overflow may vary considerably in size but preferably are smaller than 100 microns in size and more preferably smaller than 50 microns.
Fig. 3 illustrates the inclined belt classifier embodiment of the present invention. It consists of a generally inclined conveyor belt 34 supported by two conveyor endrollers 33 that are driven by a motor and a drive (not shown). Normally one of the conveyor rollers is driven and the other idles. The conveyor belt 34 may be troughed at the top flight by the use of appropriate training rollers (not shown) to permit liquid on this flight to form an aqueous pool. In the alternative, flexible sides 35 may be molded or attached to the conveyor belt for that purpose. The conveyor revolves such that the top flight moves up the incline at all times. Particulate solids mixture 10 to be classified flows onto the top flight surface 37 and forms an aqueous pool 12 that flows down the inclined of the conveyor belt 34. By way of illustration the top flight is broken away and enlarged in Fig. 4 to illustrate this pool. Underflow solids 11 fro~ the mixture that may contain rocks, lumps and other coarse particles settle to the bottom of the pool and onto the floor of the top belt flight 37 wnich may be textured, roughened or which may be provided with riffles (not shown) to hold these solids there. The aqueous pool portion 13 that contains suspended solids, such as metal and mineral values and other fine particulate matter, and/or bitumen flows down the belt incline to fall off the conveyor near the bottom endroll into a 3t)~
liquid receiver 18 as the product 13 of the classification. This liquid product 13 i5 then conveyed, pumped or transported via drain 27 to subsequent processing to remove the metal, mineral or bitumen values from the water and from the other suspended solids. The coarse underflow solids 11 of the mixture, that have settled to the floor 37 of the top flight are carried up the incline of the moving conveyor 34 and fall off the conveyor as they pass the top conveyor endroll and fall onto a chute or trough 40 for disposal. The coarse solids are normally discarded as gangue but after disposal, water drained from this gangue may be reused in the process where suitable.
Baffles 36 are provided to contain the liquid during separation and a s-tream of wash water 31 from one or more wash water pipes 32 may be used to wash metal or mineral or bitumen overflow values out of the coarse underflow solids 11 before these solids leave the conveyor for recovery.
Thus, in both embodiments described, a pool of aqueous liquid is used to classify an aqueous particulate solids mixture into a coarse underflow solids product and a liquid overflow product that contains suspended metal, mineral and/or bitumen values along with other suspended solids and/or that has bitumen floating on top of the overflow. The aqueous pool is contained by a moving floor that carries the settled underflow and lifts it overhead out of the pool and a wash water stream may be used to wash this underflow before it lea~es the classification apparatus. This wash water becomes part of the aqueous pool. The process is continuous with particulate solids mixture continuously entering the aqueous pool and underflow continuously being carried out of the pool. Overflow continuously Elows out of the pool Eor subsequent treatment as the desired product.
A placer deposit that con-tains one ounce of gold for every 21 tons of ore is classified by the process of the instant invention to recover the gold values.
Hydraulic jets of water are used to loosen and suspend the ore and a slurry pump is used to hydraulically convey the suspension mixture thus produced to the drum classifier of the instant invention.
The drum is 5 feet long, the conical section has a minimum diameter of 0.5 feet and a maximum diameter of 5 feet and is 4.5 feet long. The cylindrical portion of the drum is 5 feet in diameter, 0.5 feet long and is welded to the large end of the conical section. The cylindrical portion is closed off with an endwall that has a 2.0 feet diameter central hole for liquid outlet.
A 4 feet long, 1.0 foot wide, conveyor protrudes 2.0 feet into the interior of the drum through the central hole in the rear drum endwall and moves at a belt speed of 2 feet per second. The drum revolves near the critical rotation rate, which is defined as ~2936/r]
in revolutions per minute where r is the maximum inside drum radius in feet. For the drum of this example, this is approximately 34 RPM or about one drum revolution every 2 seconds.
3~ Thirty tons per hour of placer deposit slurry, composed of approximately 50% solids and 50% water by weight, are pumped to the drum for processing. This produces, by classification in the drum, 18 tons of coarse solids product per hour that contains 70% solids and 30% water and also contains one ounce of gold for every 225 tons of coarse solids product. Five tons per hour of wash t)~
water are introduced simultaneously into the same drum to wash gold values out oE the coarse solids before these leave the drum via the conveyor as underflow. A
total liquid product of 17 tons per hour leaves the drum through the central hole in the rear drum wall.
The liquid overflow product is composed of 86% water and 14% suspended solids. This product contains one ounce of gold for every 27 tons of liquid product. The liquid overflow is piped thereaf-ter to an oleophilic sieve separator where it is mixed with bitumen to permit capture of the gold values by the oleophilic sieve while most of the water and suspended gangue particles pass through the apertures of the oleophilic sieve. The gold values are thereafter recovered from the oleophilic sieve as a bitumen and gold product after which the gold is recovered by burning this product in a metallurgical oven with suitable slagging reagents to produce pure gold and slag that are easily separated thereafter.
EXAMPLE II
Tailings from an Alberta (Canada) hot water extraction mined tar sands plant are desanded by the inclined belt classifier as described above. The classifier is used as a pilot plant unit for desanding 10 tons per hour of tailings that contain 64% solids, 35% water and 1.0%
bitumen by weight which are pumped to the belt classifier. A total of 6.32 tons per hour of coarse solids product is produced by the belt classifier that contains 71.2% solids, 28.5% water and 0.3% bitumen and is disposed off into the tailings pond of the commercial tar sands plant. Simultaneously with the tailings, 5 tons of water per hour are introduced from the top of the same tailings pond through a pipe into the belt classifier to wash bitumen values out of the coarse solids product before this leaves the belt for ;90~
disposal as underflow. A total of 8.68 tons per hour o liquid overflow product leaves the classifier and is pumped to an oleophilic sieve separator to recover the bitumen. This liquid product stream con~ains 23.0~
solids 76.0% water and 1.0% bitumen. During subsequent separation by the oleophilic sieve separator of this liquid streaml the water and hydrophilic solids pass through the apertures of the oleophilic sieve while the bitumen is captured by the sieve and is recovered as the bitumen product. An equivalent of 0.06 tons per hour of pure bitumen are produced by the oleophilic sieve separator.
EXAMPLE III
Mined tar sands from the Asphalt Ridge, Utah deposit are separated in a pilot plant by mining the tar sand, conditioning it in a mulling or conditioning drum with steam and water to produce a tar sand slurry, classifying this slurry in a drum classifier as described in Example I above to remove coarse solids and coarse sand from the slurry, and then separating the liquid product of this drum classifier by an oleophilic sieve separator to recover the bitumen while discarding the other minerals.
In this pilot plant 10 tons per hour of mined tar sands containing 90% solids, 9~ bitumen and 1~ water by weight, are mixed with 5 tons of water and steam in the conditioning drum to produce 15 tons of tar sand slurry at a temperature of 80 degrees C. This slurry or mixture is introduced into the drum classifier of Example I through a feed pipe that introduces the slurry through the small end of the conical drum portion into the classifier. The drum revolves at 0.5 revolutions per second or 30 RPM. A stream of recycle wash water of 5 tons per hour at 45 degrees C. is : ' ~;9S3~,4 introduced through a pipe through the central opening o the rear drum wall and i9 directed into the classifier so that it will wash bitumen out of t.he solids accumlating at the drum wall in the cylindrical portion of the classifier. A total of 10.02 tons per hour of coarse solids product leave the classifier via the conveyor belt as underflow consisting of 79.8%
solids, 20.0~ water, and 0.2% bitumen by weight. The classifier produces 9.98 tons of liquid product that spills out of the central opening of the rear drum wall as overflow consisting of 10.0% solids, 81.2% water and 8.8~ bitumen. This liquid product is pumped to an oleophilic sieve separator which recovers a bitumen product that has a pure bitumen content equivalent to 0.85 tons of pure bitumen per hour.
Although the invention as has been described is deemed to be that which forms the preferred embodiments thereof, it is recognized that departures may be made therefrom and still be within the scope of the invention which is not to be limited to the details disclosed but is to be accorded the full scope of the claims so as to include any and all equivalent methods.
For example, after the liquid product leaves the classifiers of the instant invention it may be convenient to hydraulically transport this liquid through a pipe or pipe line for subsequent processing or separation and there may be an advantage to decant off some of the water from this liquid product before it is transported hydraulically for any long distances.
This decanted water may then be reused in the process of the invention as required. Such refinements will tend to improve further the economic merit of this invention for processing ores or for recovering bitumen from mined tar sands or from other mixtures.
., :
The process is useful to remove coarse solids from almost any low grade ore provided that the metal, mineral or bitumen values of the ore are of a density or par-ticles size that causes these values to settle in water less readily than the coarse gangue particles of the ore.
. ~ -
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for the continuous classification of a tar sand tailings mixture of water, particulate solids and bitumen into an underflow comprising coarse wet sand and an overflow comprising an aqueous suspension of fine particulate solids and bitumen which comprises:
a) continuously introducing said mixture as an aqueous slurry into an aqueous pool contained on the top flight of an inclined upwardly revolving endless belt conveyor wherein the forces exerted by said top flight on said aqueous pool enable the underflow portion of said mixture to migrate to the surface of said top flight while causing the overflow portion of said mixture to be retained in said pool in a suspended state, b) continuously causing the underflow contained on the surface of said moving top flight to be carried by said top flight and migrate out of and above the surface of said aqueous pool by means of the movement of said top flight and be removed as wet coarse sand, and c) continuously removing a stream of overflow from said aqueous pool as an aqueous suspension of fine particulate solids and bitumen.
a) continuously introducing said mixture as an aqueous slurry into an aqueous pool contained on the top flight of an inclined upwardly revolving endless belt conveyor wherein the forces exerted by said top flight on said aqueous pool enable the underflow portion of said mixture to migrate to the surface of said top flight while causing the overflow portion of said mixture to be retained in said pool in a suspended state, b) continuously causing the underflow contained on the surface of said moving top flight to be carried by said top flight and migrate out of and above the surface of said aqueous pool by means of the movement of said top flight and be removed as wet coarse sand, and c) continuously removing a stream of overflow from said aqueous pool as an aqueous suspension of fine particulate solids and bitumen.
2. A method as in Claim 1 wherein the size of the mineral particles contained in said overflow has an average diameter of 100 microns or smaller.
3. A method as in Claim 2 wherein the size of the mineral particles contained in said overflow has an average diameter of 50 microns or smaller.
4. A method as in Claim 1 wherein said mixture is a tailings effluent from a plant separating mined tar sands.
5. A method as in Claim 1 wherein said underflow is washed with water to remove entrained overflow therefrom.
6. A method as in Claim 1 wherein said pool is formed in the top flight of said endless belt by training rollers positioned to force the belt into a pool shape.
7. A method as in Claim 1 wherein said pool is formed with the assistance of flexible sides contained on the endless conveyor belt.
8. Apparatus for use in the continuous classification of a tar sand tailings mixture of water, particulate solids and bitumen into an underflow comprising coarse wet sand and an overflow comprising an aqueous suspension of fine particulate solids and bitumen, which apparatus includes an upwardly inclined endless belt conveyor which comprises a belt supported by endrolls, said belt being configured such that the top flight thereof can support a pool of liquid, slurry depositing means for depositing a slurry mixture onto the surface of said top flight, washing means upward along the incline from said slurry depositing means for applying wash water to materials on the top flight of said belt, means for recovering an underflow material spilling from said top flight over the upper endroll of said belt and means for removing aqueous overflow from the lower inclined end of said top flight.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US59003984A | 1984-03-15 | 1984-03-15 | |
| US590,039 | 1984-03-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1269064A true CA1269064A (en) | 1990-05-15 |
Family
ID=24360651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000476196A Expired CA1269064A (en) | 1984-03-15 | 1985-03-11 | Classification of solids in an aqueous pool by means of a moving floor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1269064A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7708146B2 (en) | 2007-11-14 | 2010-05-04 | Jan Kruyer | Hydrocyclone and associated methods |
-
1985
- 1985-03-11 CA CA000476196A patent/CA1269064A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7708146B2 (en) | 2007-11-14 | 2010-05-04 | Jan Kruyer | Hydrocyclone and associated methods |
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