CA2201797A1 - Gold extraction apparatus - Google Patents
Gold extraction apparatusInfo
- Publication number
- CA2201797A1 CA2201797A1 CA002201797A CA2201797A CA2201797A1 CA 2201797 A1 CA2201797 A1 CA 2201797A1 CA 002201797 A CA002201797 A CA 002201797A CA 2201797 A CA2201797 A CA 2201797A CA 2201797 A1 CA2201797 A1 CA 2201797A1
- Authority
- CA
- Canada
- Prior art keywords
- gold
- vessel
- compartment
- ore
- compartments
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/02—Apparatus therefor
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B11/00—Obtaining noble metals
- C22B11/08—Obtaining noble metals by cyaniding
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
Apparatus to extract gold from a gold source. The apparatus has a reactor vessel that can be rotated.
There is an inlet for the gold source and an outlet for the treated gold source. There is an inlet for extracting reagent and an outlet for used extracting reagent. There are perforate bodies in the vessel to receive an absorbent for the gold.
There is an inlet for the gold source and an outlet for the treated gold source. There is an inlet for extracting reagent and an outlet for used extracting reagent. There are perforate bodies in the vessel to receive an absorbent for the gold.
Description
220 1 ~9~
GOLD EXTRACTION APPARATUS
This invention relates to an apparatus and to a method for extracting gold from a gold source. Typically the gold source will be an ore from a mine or, more usually, a mill.
Because of its chemical inertness gold frequently occurs in elemental form and may be separated relatively easily. This is particularly so in placer mining where loose surface material is washed for gold. The high density of the gold is of value in this regard. The placer deposit can be concentrated in a concentrator whose function is simply to isolate from the ore the gold, silver or other heavy, valuable metal.
However, the majority of the world's gold is now recovered by deep mining, particularly in South Africa.
In this process mined ore is milled to reduce the particle size. The milled ore is then subjected to chemical extractants. These chemical extractants are relatively complicated because of the inertness of gold.
Recovery processes include amalgamation with mercury, the cyanidation process, gravity concentration, flotation, roasting and a combination of any of the above. Enzyme extraction is also coming into use.
The cyanidation process, although of some antiquity, is still widely practised. It hinges on the ability of gold to react with alkaline cyanides to form the aurocyanide ion, which is soluble in water. In cyanidation ore, or perhaps tailings from previous attempts at gold extraction, are leached with dilute sodium cyanide solution, typically of a concentration of 0.02 to 0.05 molar. Calcium cyanide and calcium hydroxide may also be used. The reaction is assisted greatly by aeration. The gold is separated from the ore as sodium aurocyanide, which goes into solution.
The gold is recovered from solution by using zinc dust or aluminum or, in a relatively new technique, by 22U1 7~7 extraction on activated carbon. Typically 9 to 12 kilograms of gold can be recovered by about a ton of activated carbon. When exhausted the carbon can be stripped of its gold with ethanolic sodium hydroxide.
The carbon is reactivated by roasting.
As indicated this is a relatively recent development and there are still a number of improvements that would be desirable. It would, for example, be desirable to improve extraction and to improve the stripping of the gold from the carbon.
A disadvantage of the carbon process is that it is demanding of space. The processes are essentially sequential. The ore is taken from step to step and the reagent solution, used to extract the gold, is treated in a series of steps. It would be desirable to make the apparatus more compact.
An attempt to simplify gold extraction is heap leaching where an extractant is percolated through a heap of ore. Some extractants, especially cyanide, raise environmental concerns.
The present invention renders the process of gold extraction more compact, economical and free of environmental concerns. Accordingly, the present invention, in a first aspect, is an apparatus to extract gold from a gold source comprising:
a reactor vessel;
means to rotate the reactor vessel;
an inlet for the gold source;
an outlet for the treated gold source;
an inlet for extracting reagent;
an outlet for used extracting reagent; and a plurality of perforate bodies in the vessel adapted to receive an absorbent for the gold.
In one embodiment the vessel may be divided into a plurality of compartments, for example three compartments. In such an embodiment there will be a first compartment to communicate with the inlet and to conduct a first leaching, a second compartment to receive material from the first compartment and to conduct solids liquid separation and the third compartment to receive material from the second compartment. The perforate bodies in this embodiment are positioned in the second and third compartments.
The present invention is also a method of extracting gold from a gold source using an extracting reagent able to react with gold to form a soluble gold compound, the method comprising:
containing the ore and the extracting agent in a rotating vessel; and extracting the gold on an absorbent contained within the rotating vessel.
In a further method aspect the extraction of the gold is carried out in a rotating vessel having a plurality of compartments.
Aspects of the invention are illustrated in the accompanying drawings, in which:
Figure 1 is a schematic view of a gold extraction using the apparatus of the invention;
Figure 2 is a section of an apparatus according to the present invention;
Figure 3 is a section on the line 3-3 in Figure 2;
Figure 4 is a section through a further embodiment of the apparatus of the present invention;
Figure 5 is a section on the line 5-5 in Figure 4;
and Figure 6 is a section on the line 6-6 in Figure 4.
Figure 1 shows a process for extracting gold from an ore or other gold source. First the ore is treated in a jaw crusher 2. For alluvial deposits, removal of coarse boulders using a screen may be all that is required.
The jaw crusher 2 reduces the rock to a size of about minus 3" - 4". The crushed ore is fed by conveyor 4 to a roll crusher 6 that reduces the ore to the final size.
~20 1 79~
Crushed ore is fed to a hopper 8 between the crushing components of the system and the remaining components. Hopper 8 provides surge capacity.
From the hopper 8, the ore is fed by a conveyor 10 5 to a reactor vessel 12 according to the present invention. The vessel 12 has an inlet hopper 14 that receives the ore from conveyor 10. Lime is added to the ore at 16. The extracting reagent, usually cyanide, is introduced into hopper 14 through line 18. An airline 20 is provided as air sparging is essential to the cyanide extraction of gold.
As indicated generally in Figure 1, but as shown in more detail in Figure 2, the reactor vessel 12 is provided with a series of perforate bodies in the form of 15 baskets 22.
From the vessel 12 the treated ore is fed to screen 24 and to a vacuum filter 26 for dewatering. Cyanide reagent is extracted by pump 28 and recirculated to the vessel 12. Tailings can be treated in conventional 20 manner.
In Figure 1 the jaw crusher 2 may not be necessary.
Furthermore a roll crusher 6 is illustrated but a cone crusher could be used. Generally speaking roll crushers are cheaper and lighter, features that are of advantage 25 in a small, portable crushing plant.
If a finer feed is required than that achieved by the use of a jaw crusher and roll crusher, a small closed circuit grinding mill can be incorporated into the crusher circuit. Such equipment is well known.
The reaction vessel 12 is more fully shown in Figures 2 and 3. The reactor vessel is a generally cylindrical vessel 30 mounted on rollers 32 and inclined from inlet end 34 to outlet end 36. The degree of inclination will vary depending on dwell time required and the characteristics of the ore. The vessel 12 has a peripheral gear wheel 38 driven by the output shaft of a motor (not shown). This arrangement is conventional in _ - 5 the art. It may be replaced by a drive motor and drive chain, again conventional in the art. The latter provides greater flexibility in positioning the drive motor relative to the drum than gear wheel 38. This can 5 be an advantage in a portable plant.
There is an inlet for the gold source in the form of the hopper 14 communicating with the interior of the vessel 30. There is a discharge chute 40 at the other end of the vessel. In this regard hopper 14 and chute 40 are mounted in respective end plates 42 and 44 which are fixed. Vessel 30 rotates on end plates 42 and 44. Seals 46 are provided.
There are means to agitate and lift the gold ore comprising paddles 48 extending from the inner wall of 15 the vessel 30, as shown most clearly in Figure 3. Air is fed to the vessel from line 20 through a rotary valve 50 which feeds to perforate airlines 52, for example three lines, positioned on the inner wall of the vessel 30.
The airlines 52 rotate with vessel 30 and the rotary valve 50 ensures that air is not fed to a perforate airline 52 that is above the level of the liquid within the vessel 30.
A plurality of perforate bodies 22, typically cylinders, are located in the vessel 30. The bodies 22 25 each have a threaded hatch 54. The bodies 22 may be punched plate or heavy wire screen. Each perforate body 22 contains an inner canister 56 made of a finer mesh screen containing activated charcoal. These canisters 56 may be removed from the perforate bodies 22 through 30 hatches 54. At the outlet end of the vessel there is a plurality of lift buckets 58 located on the inner surface of the vessel 30 and rotating with that vessel 30. These buckets 58 align with the mouth of the discharge chute 40 so that slurry carried to the top of the drum by a bucket 35 58 is spilt into the discharge chute 40. From there the effluent vessel passes to the screen 24 as shown in Figure 1.
2~0 1 7~7 The gold dissolves in the cyanide solution, in conventional manner. When the cyanide solution containing the gold in the form of aurocyanide (the so-called pregnant cyanide solution) contacts the activated 5 carbon the gold is absorbed on to the carbon. After an appropriate time, determined by routine experiment, the feed is turned off and the canisters 56 removed and replaced by another set of canisters. The typical period between changes would be about 3 to 10 days.
As indicated in Figure 1, the roll recovery and recycling of the cyanide solution is conventional. The cyanide solution deteriorates in use due to the formation of cyanide complexes and cyanates and a small cyanide make-up solution is therefore added through line 60.
The carbon, containing gold, is removed from the drum and gold is stripped from the carbon using caustic soda wash, again in conventional manner. The carbon can be regenerated, for example by heating to about 600~C.
Gold can be removed from the caustic soda solution 20 by electrowinning. Again this is conventional. Steel wool cathodes are used. When loaded with gold they are removed, heated in a furnace and the gold poured off as bullion.
A second embodiment of the invention is illustrated 25 in Figures 4, 5 and 6. The second embodiment differs from that of Figure 1 principally by the provision of a plurality of compartments. Where appropriate, common reference numerals, are used.
Figure 4 shows a reactor vessel 12. The vessel can 30 be rotated, as indicated by the arrow A in Figure 5, but the means of rotation is not shown in this drawing. The vessel 12 is divided into a plurality of compartments.
Inlet 60 receives feed from the feed chute 14. The material is fed to a first compartment 62 of the vessel 35 12. Compartment 62, as shown in Figures 4 and 5, is equipped with lifters 64, that function to agitate and lift the solids. There is a second compartment 66 to 220 1 ~97 receive material from the first compartment 62 to conduct solids liquid separation. There is a partition 68 between the first and second compartments.
A third compartment 70 receives material from the second compartment 66. Perforate bodies are positioned in the second and third compartments and take the form of annular bodies 72 positioned (a) between the second and third compartments and (b) the third compartment and outlet 74. There is a lifter 76 between the second and third compartments. As shown particularly in Figure 6 the lifter includes a screen 78 and restricts the size of the ore to a particular, predetermined particle size.
Similarly the third compartment has lifter 80 to move material to the outlet. Again a screen 82 is provided to 15 restrict the size of the particles.
The apparatus of Figures 4 to 6 is particularly appropriate, although not restricted to, the processing of relatively coarse ore. The inter-stage screening allows for differential solid and solution retention times in the various compartments 62, 66 and 70. The first compartment 62 provides a majority of the retention time for gold leaching by leaching solution, usually cyanide solution. The second and third compartments have increased solution retention time due to the rapid 25 removal of the coarser fractions of the ore. This increased retention time provides enhanced recovery of gold onto the activated carbon. Carbon may be advanced from the third to the second stage to provide counter current carbon movement. This is illustrated 30 diagrammatically in Figure 4 where carbon transfer piping 84 moves carbon from the downstream cage 72 the upstream cage 72. A typical ratio of carbon in compartment 66 to that in compartment 70 is approximately 1 to 4. This ratio accelerates carbon loading in compartment 66.
In general each compartment has the following metallurgical function:
~2U I ~7 Direct leaching of gold from the crushed ore to achieve a majority of gold extraction to solution is achieved in compartment 62. In general the volume in this compartment will be about 43% solid rock, 13 - 23%
solution and the remainder open space above the leaching ore. The ore characteristics in compartment 62 details will influence the exact percentages of the volume useful.
Compartment 66 is designed to maximize gold loading on the carbon as well as to provide solid/liquid separation by removal of coarse ore to prevent carbon attrition.
Carbon is included in compartment 70 to minimize the solution losses and to provide the final required leach time. Compartment 62 provides the majority of the leaching retention time. Gold loading of the solution, that is leaching, will depend on the ore grade, stage 1 extraction and relative feed rates of all solution.
The solution in ore retention time in each of the stages will differ and solution hold-up in various stages would be a benefit to leaching and carbon loading.
Solution hold-up in various stages may be achieved by dewatering the ore prior to its transfer from one stage to the other. Efficiency of the dewatering need not be high to have an impact on the solution and carbon loading.
Internal weirs or partitioning between compartments 62 and 66 and, to a lesser extent, between compartments 66 and 70, provides solution hold-up while the lifter and screen arrangement moves dewatered solids to the subsequent stage. Solution pumping between stages is not normally required as screen inefficiency, or the overflowing of the partition, will allow the movement of solution from stage to stage. The retention times of solids and liquid in compartment 66 differ. Compartment 66 is used primarily to achieve high gold loadings on the carbon held in the cage. This location of carbon allows 22~ 1 797 g the maximum contact between solution and carbon and also prevents the inclusion of grit in the carbon baskets.
Grit wears the carbon and leads to loaded carbon losses and thus gold losses.
The present invention has a number of advantages over the prior art. The equipment is compact. The invention is environmentally friendly in that there is no leachate. The closed loop system means that extracting solution is maintained. Furthermore the notion of dissolving of the gold and then immediately absorbing the dissolved gold is an advantage. Unlike the placer extraction process finds are not loss but are, in fact, more readily dissolved, thus providing increased extraction efficiency.
Although the present invention has been described in some detail by way of example for purposes of clarity and understanding, it will be apparent that certain changes and modifications may be practised within the scope of the appended claims.
GOLD EXTRACTION APPARATUS
This invention relates to an apparatus and to a method for extracting gold from a gold source. Typically the gold source will be an ore from a mine or, more usually, a mill.
Because of its chemical inertness gold frequently occurs in elemental form and may be separated relatively easily. This is particularly so in placer mining where loose surface material is washed for gold. The high density of the gold is of value in this regard. The placer deposit can be concentrated in a concentrator whose function is simply to isolate from the ore the gold, silver or other heavy, valuable metal.
However, the majority of the world's gold is now recovered by deep mining, particularly in South Africa.
In this process mined ore is milled to reduce the particle size. The milled ore is then subjected to chemical extractants. These chemical extractants are relatively complicated because of the inertness of gold.
Recovery processes include amalgamation with mercury, the cyanidation process, gravity concentration, flotation, roasting and a combination of any of the above. Enzyme extraction is also coming into use.
The cyanidation process, although of some antiquity, is still widely practised. It hinges on the ability of gold to react with alkaline cyanides to form the aurocyanide ion, which is soluble in water. In cyanidation ore, or perhaps tailings from previous attempts at gold extraction, are leached with dilute sodium cyanide solution, typically of a concentration of 0.02 to 0.05 molar. Calcium cyanide and calcium hydroxide may also be used. The reaction is assisted greatly by aeration. The gold is separated from the ore as sodium aurocyanide, which goes into solution.
The gold is recovered from solution by using zinc dust or aluminum or, in a relatively new technique, by 22U1 7~7 extraction on activated carbon. Typically 9 to 12 kilograms of gold can be recovered by about a ton of activated carbon. When exhausted the carbon can be stripped of its gold with ethanolic sodium hydroxide.
The carbon is reactivated by roasting.
As indicated this is a relatively recent development and there are still a number of improvements that would be desirable. It would, for example, be desirable to improve extraction and to improve the stripping of the gold from the carbon.
A disadvantage of the carbon process is that it is demanding of space. The processes are essentially sequential. The ore is taken from step to step and the reagent solution, used to extract the gold, is treated in a series of steps. It would be desirable to make the apparatus more compact.
An attempt to simplify gold extraction is heap leaching where an extractant is percolated through a heap of ore. Some extractants, especially cyanide, raise environmental concerns.
The present invention renders the process of gold extraction more compact, economical and free of environmental concerns. Accordingly, the present invention, in a first aspect, is an apparatus to extract gold from a gold source comprising:
a reactor vessel;
means to rotate the reactor vessel;
an inlet for the gold source;
an outlet for the treated gold source;
an inlet for extracting reagent;
an outlet for used extracting reagent; and a plurality of perforate bodies in the vessel adapted to receive an absorbent for the gold.
In one embodiment the vessel may be divided into a plurality of compartments, for example three compartments. In such an embodiment there will be a first compartment to communicate with the inlet and to conduct a first leaching, a second compartment to receive material from the first compartment and to conduct solids liquid separation and the third compartment to receive material from the second compartment. The perforate bodies in this embodiment are positioned in the second and third compartments.
The present invention is also a method of extracting gold from a gold source using an extracting reagent able to react with gold to form a soluble gold compound, the method comprising:
containing the ore and the extracting agent in a rotating vessel; and extracting the gold on an absorbent contained within the rotating vessel.
In a further method aspect the extraction of the gold is carried out in a rotating vessel having a plurality of compartments.
Aspects of the invention are illustrated in the accompanying drawings, in which:
Figure 1 is a schematic view of a gold extraction using the apparatus of the invention;
Figure 2 is a section of an apparatus according to the present invention;
Figure 3 is a section on the line 3-3 in Figure 2;
Figure 4 is a section through a further embodiment of the apparatus of the present invention;
Figure 5 is a section on the line 5-5 in Figure 4;
and Figure 6 is a section on the line 6-6 in Figure 4.
Figure 1 shows a process for extracting gold from an ore or other gold source. First the ore is treated in a jaw crusher 2. For alluvial deposits, removal of coarse boulders using a screen may be all that is required.
The jaw crusher 2 reduces the rock to a size of about minus 3" - 4". The crushed ore is fed by conveyor 4 to a roll crusher 6 that reduces the ore to the final size.
~20 1 79~
Crushed ore is fed to a hopper 8 between the crushing components of the system and the remaining components. Hopper 8 provides surge capacity.
From the hopper 8, the ore is fed by a conveyor 10 5 to a reactor vessel 12 according to the present invention. The vessel 12 has an inlet hopper 14 that receives the ore from conveyor 10. Lime is added to the ore at 16. The extracting reagent, usually cyanide, is introduced into hopper 14 through line 18. An airline 20 is provided as air sparging is essential to the cyanide extraction of gold.
As indicated generally in Figure 1, but as shown in more detail in Figure 2, the reactor vessel 12 is provided with a series of perforate bodies in the form of 15 baskets 22.
From the vessel 12 the treated ore is fed to screen 24 and to a vacuum filter 26 for dewatering. Cyanide reagent is extracted by pump 28 and recirculated to the vessel 12. Tailings can be treated in conventional 20 manner.
In Figure 1 the jaw crusher 2 may not be necessary.
Furthermore a roll crusher 6 is illustrated but a cone crusher could be used. Generally speaking roll crushers are cheaper and lighter, features that are of advantage 25 in a small, portable crushing plant.
If a finer feed is required than that achieved by the use of a jaw crusher and roll crusher, a small closed circuit grinding mill can be incorporated into the crusher circuit. Such equipment is well known.
The reaction vessel 12 is more fully shown in Figures 2 and 3. The reactor vessel is a generally cylindrical vessel 30 mounted on rollers 32 and inclined from inlet end 34 to outlet end 36. The degree of inclination will vary depending on dwell time required and the characteristics of the ore. The vessel 12 has a peripheral gear wheel 38 driven by the output shaft of a motor (not shown). This arrangement is conventional in _ - 5 the art. It may be replaced by a drive motor and drive chain, again conventional in the art. The latter provides greater flexibility in positioning the drive motor relative to the drum than gear wheel 38. This can 5 be an advantage in a portable plant.
There is an inlet for the gold source in the form of the hopper 14 communicating with the interior of the vessel 30. There is a discharge chute 40 at the other end of the vessel. In this regard hopper 14 and chute 40 are mounted in respective end plates 42 and 44 which are fixed. Vessel 30 rotates on end plates 42 and 44. Seals 46 are provided.
There are means to agitate and lift the gold ore comprising paddles 48 extending from the inner wall of 15 the vessel 30, as shown most clearly in Figure 3. Air is fed to the vessel from line 20 through a rotary valve 50 which feeds to perforate airlines 52, for example three lines, positioned on the inner wall of the vessel 30.
The airlines 52 rotate with vessel 30 and the rotary valve 50 ensures that air is not fed to a perforate airline 52 that is above the level of the liquid within the vessel 30.
A plurality of perforate bodies 22, typically cylinders, are located in the vessel 30. The bodies 22 25 each have a threaded hatch 54. The bodies 22 may be punched plate or heavy wire screen. Each perforate body 22 contains an inner canister 56 made of a finer mesh screen containing activated charcoal. These canisters 56 may be removed from the perforate bodies 22 through 30 hatches 54. At the outlet end of the vessel there is a plurality of lift buckets 58 located on the inner surface of the vessel 30 and rotating with that vessel 30. These buckets 58 align with the mouth of the discharge chute 40 so that slurry carried to the top of the drum by a bucket 35 58 is spilt into the discharge chute 40. From there the effluent vessel passes to the screen 24 as shown in Figure 1.
2~0 1 7~7 The gold dissolves in the cyanide solution, in conventional manner. When the cyanide solution containing the gold in the form of aurocyanide (the so-called pregnant cyanide solution) contacts the activated 5 carbon the gold is absorbed on to the carbon. After an appropriate time, determined by routine experiment, the feed is turned off and the canisters 56 removed and replaced by another set of canisters. The typical period between changes would be about 3 to 10 days.
As indicated in Figure 1, the roll recovery and recycling of the cyanide solution is conventional. The cyanide solution deteriorates in use due to the formation of cyanide complexes and cyanates and a small cyanide make-up solution is therefore added through line 60.
The carbon, containing gold, is removed from the drum and gold is stripped from the carbon using caustic soda wash, again in conventional manner. The carbon can be regenerated, for example by heating to about 600~C.
Gold can be removed from the caustic soda solution 20 by electrowinning. Again this is conventional. Steel wool cathodes are used. When loaded with gold they are removed, heated in a furnace and the gold poured off as bullion.
A second embodiment of the invention is illustrated 25 in Figures 4, 5 and 6. The second embodiment differs from that of Figure 1 principally by the provision of a plurality of compartments. Where appropriate, common reference numerals, are used.
Figure 4 shows a reactor vessel 12. The vessel can 30 be rotated, as indicated by the arrow A in Figure 5, but the means of rotation is not shown in this drawing. The vessel 12 is divided into a plurality of compartments.
Inlet 60 receives feed from the feed chute 14. The material is fed to a first compartment 62 of the vessel 35 12. Compartment 62, as shown in Figures 4 and 5, is equipped with lifters 64, that function to agitate and lift the solids. There is a second compartment 66 to 220 1 ~97 receive material from the first compartment 62 to conduct solids liquid separation. There is a partition 68 between the first and second compartments.
A third compartment 70 receives material from the second compartment 66. Perforate bodies are positioned in the second and third compartments and take the form of annular bodies 72 positioned (a) between the second and third compartments and (b) the third compartment and outlet 74. There is a lifter 76 between the second and third compartments. As shown particularly in Figure 6 the lifter includes a screen 78 and restricts the size of the ore to a particular, predetermined particle size.
Similarly the third compartment has lifter 80 to move material to the outlet. Again a screen 82 is provided to 15 restrict the size of the particles.
The apparatus of Figures 4 to 6 is particularly appropriate, although not restricted to, the processing of relatively coarse ore. The inter-stage screening allows for differential solid and solution retention times in the various compartments 62, 66 and 70. The first compartment 62 provides a majority of the retention time for gold leaching by leaching solution, usually cyanide solution. The second and third compartments have increased solution retention time due to the rapid 25 removal of the coarser fractions of the ore. This increased retention time provides enhanced recovery of gold onto the activated carbon. Carbon may be advanced from the third to the second stage to provide counter current carbon movement. This is illustrated 30 diagrammatically in Figure 4 where carbon transfer piping 84 moves carbon from the downstream cage 72 the upstream cage 72. A typical ratio of carbon in compartment 66 to that in compartment 70 is approximately 1 to 4. This ratio accelerates carbon loading in compartment 66.
In general each compartment has the following metallurgical function:
~2U I ~7 Direct leaching of gold from the crushed ore to achieve a majority of gold extraction to solution is achieved in compartment 62. In general the volume in this compartment will be about 43% solid rock, 13 - 23%
solution and the remainder open space above the leaching ore. The ore characteristics in compartment 62 details will influence the exact percentages of the volume useful.
Compartment 66 is designed to maximize gold loading on the carbon as well as to provide solid/liquid separation by removal of coarse ore to prevent carbon attrition.
Carbon is included in compartment 70 to minimize the solution losses and to provide the final required leach time. Compartment 62 provides the majority of the leaching retention time. Gold loading of the solution, that is leaching, will depend on the ore grade, stage 1 extraction and relative feed rates of all solution.
The solution in ore retention time in each of the stages will differ and solution hold-up in various stages would be a benefit to leaching and carbon loading.
Solution hold-up in various stages may be achieved by dewatering the ore prior to its transfer from one stage to the other. Efficiency of the dewatering need not be high to have an impact on the solution and carbon loading.
Internal weirs or partitioning between compartments 62 and 66 and, to a lesser extent, between compartments 66 and 70, provides solution hold-up while the lifter and screen arrangement moves dewatered solids to the subsequent stage. Solution pumping between stages is not normally required as screen inefficiency, or the overflowing of the partition, will allow the movement of solution from stage to stage. The retention times of solids and liquid in compartment 66 differ. Compartment 66 is used primarily to achieve high gold loadings on the carbon held in the cage. This location of carbon allows 22~ 1 797 g the maximum contact between solution and carbon and also prevents the inclusion of grit in the carbon baskets.
Grit wears the carbon and leads to loaded carbon losses and thus gold losses.
The present invention has a number of advantages over the prior art. The equipment is compact. The invention is environmentally friendly in that there is no leachate. The closed loop system means that extracting solution is maintained. Furthermore the notion of dissolving of the gold and then immediately absorbing the dissolved gold is an advantage. Unlike the placer extraction process finds are not loss but are, in fact, more readily dissolved, thus providing increased extraction efficiency.
Although the present invention has been described in some detail by way of example for purposes of clarity and understanding, it will be apparent that certain changes and modifications may be practised within the scope of the appended claims.
Claims (23)
1. Apparatus to extract gold from a gold source comprising:
a reactor vessel;
means to rotate the reactor vessel;
an inlet for the gold source;
an outlet for the treated gold source;
an inlet for extracting reagent;
an outlet for used extracting reagent;
a plurality of perforate bodies in the vessel adapted to receive an absorbent for the gold.
a reactor vessel;
means to rotate the reactor vessel;
an inlet for the gold source;
an outlet for the treated gold source;
an inlet for extracting reagent;
an outlet for used extracting reagent;
a plurality of perforate bodies in the vessel adapted to receive an absorbent for the gold.
2. Apparatus as claimed in claim 1 including means to agitate the gold source as the vessel rotates.
3. Apparatus as claimed in claim 1 including means to recirculate the extracting reagent.
4. Apparatus as claimed in claim 3 in which the means to recirculate the extracting reagent is a conduit joining the outlet to the inlet.
5. Apparatus as claimed in claim 1 in which the inlet for the ore and the extracting reagent are the same.
6. Apparatus as claimed in claim 1 in which the perforate bodies are cylinders attached to the vessel and extending generally radially of the vessel.
7. Apparatus as claimed in claim 1 in which the absorbent is activated carbon and the perforations in the perforate body are dimensioned to retain the carbon.
8. Apparatus as claimed in claim 1 in which the vessel is divided into a plurality of compartments.
9. Apparatus as claimed in claim 8 in which there are three compartments.
10. Apparatus as claimed in claim 9 having a first compartment to communicate with the inlet to conduct the first leaching;
a second compartment to receive material from the first compartment and to conduct leaching and a solid/liquid separation;
a third compartment to receive material from the second compartment;
perforate bodies in the second and third compartments.
a second compartment to receive material from the first compartment and to conduct leaching and a solid/liquid separation;
a third compartment to receive material from the second compartment;
perforate bodies in the second and third compartments.
11. Apparatus as claimed in claim 10 in which the first compartment has lifters to agitate the ore.
12. Apparatus as claimed in claim 10 including a partition between the first and second compartments.
13. Apparatus as claimed in claim 8 having a second lifter between the second and third compartments;
a screen between said second and third compartments to restrict the ore particle size.
a screen between said second and third compartments to restrict the ore particle size.
14. Apparatus as claimed in claim 8 having a third lifter to move the material to the outlet;
a screen to restrict the size particles fed to the outlet.
a screen to restrict the size particles fed to the outlet.
15. Apparatus as claimed in claim 8 in which the carbon is located in bodies between the second and third compartments and the third compartment and the outlet.
16. Apparatus as claimed in claim 15 in which the bodies are annular bodies.
17. A method to extract gold from a gold source using an extracting reagent able to react with the gold to form a soluble gold compound, the method comprising:
containing the ore and extracting agent in a rotating vessel;
absorbing the gold from the extracting agent with an absorbent contained in the rotating vessel.
containing the ore and extracting agent in a rotating vessel;
absorbing the gold from the extracting agent with an absorbent contained in the rotating vessel.
18. A method as claimed in claim 17 including feeding the ore continuously to the vessel.
19. A method as claimed in claim 17 including feeding the extracting agent continually to the vessel.
20. A method as claimed in claim 17 including agitating the ore as the vessel rotates.
21. A method as claimed in claim 17 in which the absorbent is carbon.
22. A method as claimed in claim 21 in which the carbon is contained in perforate bodies extending generally radially of the vessel.
23. A method as claimed in claim 17 in which the rotating vessel includes a plurality of stages.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002201797A CA2201797A1 (en) | 1997-04-04 | 1997-04-04 | Gold extraction apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002201797A CA2201797A1 (en) | 1997-04-04 | 1997-04-04 | Gold extraction apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2201797A1 true CA2201797A1 (en) | 1998-10-04 |
Family
ID=4160324
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002201797A Abandoned CA2201797A1 (en) | 1997-04-04 | 1997-04-04 | Gold extraction apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2201797A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010138094A1 (en) * | 2009-05-29 | 2010-12-02 | Lvov Boris Davidovich | Method and device for extracting free gold from placer deposits and ores |
| RU2458162C1 (en) * | 2011-06-08 | 2012-08-10 | Закрытое акционерное общество "Золотодобывающая компания "Полюс" | Method of gold extraction from gravity concentrates |
| IT202200007067A1 (en) * | 2022-04-08 | 2023-10-08 | Opi Group Soc A Responsabilita Limitata Semplificata | ALLOY DISSOLUTION PLANT. |
-
1997
- 1997-04-04 CA CA002201797A patent/CA2201797A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010138094A1 (en) * | 2009-05-29 | 2010-12-02 | Lvov Boris Davidovich | Method and device for extracting free gold from placer deposits and ores |
| RU2458162C1 (en) * | 2011-06-08 | 2012-08-10 | Закрытое акционерное общество "Золотодобывающая компания "Полюс" | Method of gold extraction from gravity concentrates |
| IT202200007067A1 (en) * | 2022-04-08 | 2023-10-08 | Opi Group Soc A Responsabilita Limitata Semplificata | ALLOY DISSOLUTION PLANT. |
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