CA2067841A1 - Process for leaching gold and silver - Google Patents
Process for leaching gold and silverInfo
- Publication number
- CA2067841A1 CA2067841A1 CA002067841A CA2067841A CA2067841A1 CA 2067841 A1 CA2067841 A1 CA 2067841A1 CA 002067841 A CA002067841 A CA 002067841A CA 2067841 A CA2067841 A CA 2067841A CA 2067841 A1 CA2067841 A1 CA 2067841A1
- Authority
- CA
- Canada
- Prior art keywords
- peroxoborate
- leaching
- leached
- cyanide
- mill
- 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
- C22B11/00—Obtaining noble metals
- C22B11/08—Obtaining noble metals by cyaniding
Abstract
ABSTRACT OF THE DISCLOSURE
In the so-called cyanidation-in-mill technique, the ores, ore concentrates and waste material from previous incomplete leachings which are to be leached are treated in the mill with a cyanide-containing leaching solution, gold and silver being at least partly leached. Compared with the known cyanidation-in-mill technique in the presence of hydrogen peroxide, the gold yield can be considerably increased if leaching is carried out in the presence of a peroxoborate compound. The peroxoborate may be present in solid and/or dissolved form. 10 to 60 equivalents peroxoborate are preferably used per t of the material to be leached.
In the so-called cyanidation-in-mill technique, the ores, ore concentrates and waste material from previous incomplete leachings which are to be leached are treated in the mill with a cyanide-containing leaching solution, gold and silver being at least partly leached. Compared with the known cyanidation-in-mill technique in the presence of hydrogen peroxide, the gold yield can be considerably increased if leaching is carried out in the presence of a peroxoborate compound. The peroxoborate may be present in solid and/or dissolved form. 10 to 60 equivalents peroxoborate are preferably used per t of the material to be leached.
Description
2~6784~
This invention relates to a process for leaching gold and silver from ores, ore concentrates and waste material from previous incomplete leachings by grinding of the material to be leached in the presence of a cyanide-containing leaching solution which has a pH value of 8 to 13 and which contains a peroxo compound.
The leaching of noble metals forming cyano complexes, particularly gold and silver, from ores, ore concentrates and other particulate materials, such as for example waste material from previous incomplete leachings, using a cyanide-containing alkaline leaching solution and an oxidizing agent has long been known and has been practised on an industrial scale ~or more than 100 years.
In so-called heap leaching, the ore precrushed to a particle size of 10 to 50 mm i8 heaped up and sprayed with an aqueous cyanide ~olution. Atmospheric oxygen i8 normally used as the oxidizing agent, although peroxo compounds may al~o be added to the ore heap or to the leaching solution (DE-PS 38 30 703, German patent application P 40 17 899.4, GB-A 2,219,474).
In so-called agitation leaching, finely ground ore is leached in tanks or other vessels. The gold recovery rate is higher in this process than in heap leaching, although the process costs are also significantly higher. In agitation leaching, the ore to be leached has to be ground on average to a particle size of smaller than 100 ~m. In most cases, grinding has to be carried out to the extent where at least 80% of the particles are smaller than 45 ~m in size.
Known discontinuous and continuous wet mills, more particularly ball mills and rod mills, are used to grind the .:
. , ~ ,. .
~.; ,- , , .
ore. Grinding is carried out in a single stage, but mostly in two or more stages, any oversize particles always being recycled. Cyanide and, optionally, other leaching chemicals are then added to the resulting pulp of the ground ore and, generally, water, the whole then being delivered to the leaching tanks.
In agitation leaching, the leaching time in cases where air is used for aeration is generally between 15 and 30 hour~, but can be considerably shortened by using peroxo compounds, such as hydrogen peroxide, calcium peroxide or peroxoborates, instead of or in addition to the air (DE-PS 36 37 082, DE-PS 38 30 703, German patent application P 40 17 899.4).
For some time now, certain mines have been using the so-called cyanidation-in-mill technique. In this method of leaching, the cyanide i5 added before or during grinding and the re~idence time of the ore in the mill is used to shorten the leaching time in the tanks used for agitation leaching.
Wherea~ pa~able results can actually be obtained in the mill in the leaching of fully oxidized ore~, this method i~ not really ~uitable for the leaching of 6ulfidic ores because, in their ca~e, reductive conditions prevail in the mill and too little, if any, oxygen is available for leaching. To make ~ul~ide-containing ores more accessible to the cyanidation-in-mill technique, oxidizing agents have also been used by various mines. Whereas no improvement could be obtained with pure oxygen, the gold yields in the mill could be increased and the consumption of NaCN reduced by using hydrogen peroxide ~CA 102(14): 117216r; Smith, M.E. et al. in Proc.
SME Fall Meeting 1983, 41, 43-49, ed. Hiskey, J. Brent, Soc.
Min. Eng. AIME : Littleton, Colo.).
' ";
: , , - .
: :;
2067~1 It would be desirable to improve the cyanidation-in-mill technique to the extent that an even higher gold yield could be obtained in relation to the use of hydrogen peroxide. -S Accordingly, it would be possible not only further to shorten the overall leaching time (time required for grinding and subsequent agitation leaching) for a high gold yield, but also - where possible - to dispense with the need for agitation leaching.
In one aspect the invention provides a process for leaching gold and silver from ores, ore concentrates and waste material from previous incomplete leachings by grinding of the material to be leached in the presence of a cyanide-containing leaching solution which has a pH value of 8 to 13 and which contains a peroxo compound, characterized in that at least one peroxoborate compound is present as the peroxo compound.
It is cru¢ial to the process according to the invention that an effective quantity of peroxoborate be present in dissolved and/or very finely divided form. The total quantity of peroxoborate required may be present in the mill from the beginning of the leaching process. Alternatively, the peroxoborate is added during leaching in one or more portions, for example before each grinding stage of a multi~tage grinding process, or is formed in situ from an added borate and hydrogen peroxide. The addition of a peroxoborate is preferred to formation in ~itu in the leaching pulp. The peroxoborate may be added in powder form or as an aqueous solution or suspension to the material to be leached, to the cyanide-containing leaching solution or to the leaching pulp.
: , ' ' '~
.
, :, - , ~, ~: .,- i, 3a The effective quantity of peroxoborate, which depends to a large extent on the material to be leached, may readily be determined by preliminary tests. A quantity of 1 to 100 equivalents peroxoborate, expressed as B03, per t of the material to be leached will generally be sufficient. The quantity of peroxoborate added is preferably between lO and ;
60 equivalents. As active oxygen compounds, peroxoborates and the hydrogen peroxide formed by hydrolysis give '; , - :
.
; , .: . :~ :
l . , . ': :
. ~ , - :
2~678~1 off oxygen. The oxygen, the hydrogen peroxide and the peroxoborate may serve as oxidiæing agents in the leaching process.
Suitable peroxoborates, by which are also meant hydrates thereof, are those of the alkali and alkaline earth metals, although peroxoborates of other metals, such as zinc for example, may also be used in principle.
Commercially available peroxoborates, namely the so-called sodium perborate mono- and tetrahydrate and also calcium perborate, may be used with particular advantage. So-called superoxidized perborates, which are known from DE-OS 28 11 554 and from DE-OS 35 05 158, may also be used.
In the same way as heap and agitation leaching, cyanidation-in-mill leaching is also carried out at a pH
value of 8 to 13 and preferably at a pH value of 9 to 12.
The pH value is adjusted in known manner with alkalis, such as in particular milk of lime and sodium hydroxide. It may be advisable during the grinding process to adapt the p~ to values recognized as optimal.
The cyanide content, expressed as CN, in the leaching solution is normally between 0.005 and 2.5% by weight.
Cyanide contents of 0.02 to 0.2% by weight are preferred.
Cyanide i~ used in the ~orm o~ alkali metal cyanide, more particularly sodium cyanide, or in the form of calcium cyanide, for example in the form o~ so-called black cya-nide. The cyanide may be added in solid or dissolved form to a water-based pulp containing the material to be leached or, alternatively, a cyanide-containing leaching solution is directly used for the preparation of the leaching pulp.
Known wet grinding units may be used for leaching in accordance with the invention, ball mills and rod mills being preferred. The grinding time depends on the material to be leached and the desired degree of extraction. The grinding time is normally between 15 minutes and 2 hours.
The solids concentration of the leaching pulp during 2~78~
grinding may vary within wide limits and is normally between 25 and 60% by weight. The degree of grinding may be in the range typical of agitation leaching.
~n completion of grinding, the leaching pulp may if necessary be subjected to agitation leaching or to pressure leaching in order further to increase the extraction level.
Otherwise the noble metal/cyano complexes present in dissolved form in the leaching pump may be separated off for the further extraction of noble metal by known proces-ses, for example by the carbon-in-pulp (CIP) and resin-in-pulp (RIP) processes and by the Merrill-Crowe process.
Whereas the extraction kinetics observed during cyanidation-in-mill leaching are similar to those observed during agitation leaching in accordance with DE-PS 36 37 082 where hydrogen peroxide is used as the oxidation agent, extraction is surprisingly accelerated by using an equiva-lent quantity of a peroxoborate. The gold yield is thus increased for the same leaching time. In some case~, therefore, there is no need for agitation leaching after leach$ng in the mill. In addition, the use of peroxoborate reduces the consumption of cyanide. The factors mentioned increase the economy with which gold and silver are leached ~rom ores, ore concentrates and waste material from pre-vious incomplete leachings, for example heap leachings.
The advantages of the peroxoborate are all the more ~urprising insofar as other peroxo compounds, including calcium peroxide, sodium percarbonate and ammonium peroxo-disulfate, proved to be less effective than hydrogen peroxide in regard to the gold yield.
The following Examples illustrate the surprising effect of peroxoborates in relation to other peroxo com-pounds in cyanidation-in-mill leaching.
2~67~41 Bxample~
A sulfide-containing ore, the so-called mill feed of the Vumbachikwe mine in Zimbabwe, was used in all the tests.
With this ore, the cyanide-leachable gold, 80 to 85% of the `~
gold content, can be extracted in 4 to 6 hours where hydrogen peroxide is used in accordance with DE-PS 36 37 082.
The leaching tests using the cyanidation-in-mill technigue were carried out in a stainless steel rod mill with a total capacity of 4.5 1. Twelve stainless steel rods (18.2 cm long, 2.5 cm in diameter) were used as the grinding elements, occupying 24% of the mill volume. The grindings were each carried out with 400 g ore and 600 g water (40%
solids). The volume of the ore pulp formed occupied another 16% o~ the mill so that the total filling of the mill was 40%.
Other leaching parameters were:
NaCN addition: 0.5 kg/t ore CaO addition: 1.25 kg/t ore Grinding time: 1 h Grinding speed: 60 r.p.m.
pH at the end of grinding: 11.5 - 12.0 The various oxidizing agents and the lime were introduced into the mill at the beginning of grinding. On completion of grinding, the gold yield (leached gold, based on the total gold content of the ore), the 2 content (ppm) in the leaching solution, as determined with an 2 ele¢trode, and the cyanide consumption in kg/t ore (cyanide used minus residual cyanide) were determined.
' . ~ , ~ - , :
-2~78~
The results of Examples E 1 to E 5 according to the -invention and those of Comparison Examples C 1 to C 7 are set out in the following Table, reflecting the superior effect of added perborates (E l to E 4): although sodium perborate (E
5) formed in ~itu leads to substantially the same gold yield as H202, the consumption of NaCN could be reduced.
,, : . ,~ . ~, -- ~
:, -
This invention relates to a process for leaching gold and silver from ores, ore concentrates and waste material from previous incomplete leachings by grinding of the material to be leached in the presence of a cyanide-containing leaching solution which has a pH value of 8 to 13 and which contains a peroxo compound.
The leaching of noble metals forming cyano complexes, particularly gold and silver, from ores, ore concentrates and other particulate materials, such as for example waste material from previous incomplete leachings, using a cyanide-containing alkaline leaching solution and an oxidizing agent has long been known and has been practised on an industrial scale ~or more than 100 years.
In so-called heap leaching, the ore precrushed to a particle size of 10 to 50 mm i8 heaped up and sprayed with an aqueous cyanide ~olution. Atmospheric oxygen i8 normally used as the oxidizing agent, although peroxo compounds may al~o be added to the ore heap or to the leaching solution (DE-PS 38 30 703, German patent application P 40 17 899.4, GB-A 2,219,474).
In so-called agitation leaching, finely ground ore is leached in tanks or other vessels. The gold recovery rate is higher in this process than in heap leaching, although the process costs are also significantly higher. In agitation leaching, the ore to be leached has to be ground on average to a particle size of smaller than 100 ~m. In most cases, grinding has to be carried out to the extent where at least 80% of the particles are smaller than 45 ~m in size.
Known discontinuous and continuous wet mills, more particularly ball mills and rod mills, are used to grind the .:
. , ~ ,. .
~.; ,- , , .
ore. Grinding is carried out in a single stage, but mostly in two or more stages, any oversize particles always being recycled. Cyanide and, optionally, other leaching chemicals are then added to the resulting pulp of the ground ore and, generally, water, the whole then being delivered to the leaching tanks.
In agitation leaching, the leaching time in cases where air is used for aeration is generally between 15 and 30 hour~, but can be considerably shortened by using peroxo compounds, such as hydrogen peroxide, calcium peroxide or peroxoborates, instead of or in addition to the air (DE-PS 36 37 082, DE-PS 38 30 703, German patent application P 40 17 899.4).
For some time now, certain mines have been using the so-called cyanidation-in-mill technique. In this method of leaching, the cyanide i5 added before or during grinding and the re~idence time of the ore in the mill is used to shorten the leaching time in the tanks used for agitation leaching.
Wherea~ pa~able results can actually be obtained in the mill in the leaching of fully oxidized ore~, this method i~ not really ~uitable for the leaching of 6ulfidic ores because, in their ca~e, reductive conditions prevail in the mill and too little, if any, oxygen is available for leaching. To make ~ul~ide-containing ores more accessible to the cyanidation-in-mill technique, oxidizing agents have also been used by various mines. Whereas no improvement could be obtained with pure oxygen, the gold yields in the mill could be increased and the consumption of NaCN reduced by using hydrogen peroxide ~CA 102(14): 117216r; Smith, M.E. et al. in Proc.
SME Fall Meeting 1983, 41, 43-49, ed. Hiskey, J. Brent, Soc.
Min. Eng. AIME : Littleton, Colo.).
' ";
: , , - .
: :;
2067~1 It would be desirable to improve the cyanidation-in-mill technique to the extent that an even higher gold yield could be obtained in relation to the use of hydrogen peroxide. -S Accordingly, it would be possible not only further to shorten the overall leaching time (time required for grinding and subsequent agitation leaching) for a high gold yield, but also - where possible - to dispense with the need for agitation leaching.
In one aspect the invention provides a process for leaching gold and silver from ores, ore concentrates and waste material from previous incomplete leachings by grinding of the material to be leached in the presence of a cyanide-containing leaching solution which has a pH value of 8 to 13 and which contains a peroxo compound, characterized in that at least one peroxoborate compound is present as the peroxo compound.
It is cru¢ial to the process according to the invention that an effective quantity of peroxoborate be present in dissolved and/or very finely divided form. The total quantity of peroxoborate required may be present in the mill from the beginning of the leaching process. Alternatively, the peroxoborate is added during leaching in one or more portions, for example before each grinding stage of a multi~tage grinding process, or is formed in situ from an added borate and hydrogen peroxide. The addition of a peroxoborate is preferred to formation in ~itu in the leaching pulp. The peroxoborate may be added in powder form or as an aqueous solution or suspension to the material to be leached, to the cyanide-containing leaching solution or to the leaching pulp.
: , ' ' '~
.
, :, - , ~, ~: .,- i, 3a The effective quantity of peroxoborate, which depends to a large extent on the material to be leached, may readily be determined by preliminary tests. A quantity of 1 to 100 equivalents peroxoborate, expressed as B03, per t of the material to be leached will generally be sufficient. The quantity of peroxoborate added is preferably between lO and ;
60 equivalents. As active oxygen compounds, peroxoborates and the hydrogen peroxide formed by hydrolysis give '; , - :
.
; , .: . :~ :
l . , . ': :
. ~ , - :
2~678~1 off oxygen. The oxygen, the hydrogen peroxide and the peroxoborate may serve as oxidiæing agents in the leaching process.
Suitable peroxoborates, by which are also meant hydrates thereof, are those of the alkali and alkaline earth metals, although peroxoborates of other metals, such as zinc for example, may also be used in principle.
Commercially available peroxoborates, namely the so-called sodium perborate mono- and tetrahydrate and also calcium perborate, may be used with particular advantage. So-called superoxidized perborates, which are known from DE-OS 28 11 554 and from DE-OS 35 05 158, may also be used.
In the same way as heap and agitation leaching, cyanidation-in-mill leaching is also carried out at a pH
value of 8 to 13 and preferably at a pH value of 9 to 12.
The pH value is adjusted in known manner with alkalis, such as in particular milk of lime and sodium hydroxide. It may be advisable during the grinding process to adapt the p~ to values recognized as optimal.
The cyanide content, expressed as CN, in the leaching solution is normally between 0.005 and 2.5% by weight.
Cyanide contents of 0.02 to 0.2% by weight are preferred.
Cyanide i~ used in the ~orm o~ alkali metal cyanide, more particularly sodium cyanide, or in the form of calcium cyanide, for example in the form o~ so-called black cya-nide. The cyanide may be added in solid or dissolved form to a water-based pulp containing the material to be leached or, alternatively, a cyanide-containing leaching solution is directly used for the preparation of the leaching pulp.
Known wet grinding units may be used for leaching in accordance with the invention, ball mills and rod mills being preferred. The grinding time depends on the material to be leached and the desired degree of extraction. The grinding time is normally between 15 minutes and 2 hours.
The solids concentration of the leaching pulp during 2~78~
grinding may vary within wide limits and is normally between 25 and 60% by weight. The degree of grinding may be in the range typical of agitation leaching.
~n completion of grinding, the leaching pulp may if necessary be subjected to agitation leaching or to pressure leaching in order further to increase the extraction level.
Otherwise the noble metal/cyano complexes present in dissolved form in the leaching pump may be separated off for the further extraction of noble metal by known proces-ses, for example by the carbon-in-pulp (CIP) and resin-in-pulp (RIP) processes and by the Merrill-Crowe process.
Whereas the extraction kinetics observed during cyanidation-in-mill leaching are similar to those observed during agitation leaching in accordance with DE-PS 36 37 082 where hydrogen peroxide is used as the oxidation agent, extraction is surprisingly accelerated by using an equiva-lent quantity of a peroxoborate. The gold yield is thus increased for the same leaching time. In some case~, therefore, there is no need for agitation leaching after leach$ng in the mill. In addition, the use of peroxoborate reduces the consumption of cyanide. The factors mentioned increase the economy with which gold and silver are leached ~rom ores, ore concentrates and waste material from pre-vious incomplete leachings, for example heap leachings.
The advantages of the peroxoborate are all the more ~urprising insofar as other peroxo compounds, including calcium peroxide, sodium percarbonate and ammonium peroxo-disulfate, proved to be less effective than hydrogen peroxide in regard to the gold yield.
The following Examples illustrate the surprising effect of peroxoborates in relation to other peroxo com-pounds in cyanidation-in-mill leaching.
2~67~41 Bxample~
A sulfide-containing ore, the so-called mill feed of the Vumbachikwe mine in Zimbabwe, was used in all the tests.
With this ore, the cyanide-leachable gold, 80 to 85% of the `~
gold content, can be extracted in 4 to 6 hours where hydrogen peroxide is used in accordance with DE-PS 36 37 082.
The leaching tests using the cyanidation-in-mill technigue were carried out in a stainless steel rod mill with a total capacity of 4.5 1. Twelve stainless steel rods (18.2 cm long, 2.5 cm in diameter) were used as the grinding elements, occupying 24% of the mill volume. The grindings were each carried out with 400 g ore and 600 g water (40%
solids). The volume of the ore pulp formed occupied another 16% o~ the mill so that the total filling of the mill was 40%.
Other leaching parameters were:
NaCN addition: 0.5 kg/t ore CaO addition: 1.25 kg/t ore Grinding time: 1 h Grinding speed: 60 r.p.m.
pH at the end of grinding: 11.5 - 12.0 The various oxidizing agents and the lime were introduced into the mill at the beginning of grinding. On completion of grinding, the gold yield (leached gold, based on the total gold content of the ore), the 2 content (ppm) in the leaching solution, as determined with an 2 ele¢trode, and the cyanide consumption in kg/t ore (cyanide used minus residual cyanide) were determined.
' . ~ , ~ - , :
-2~78~
The results of Examples E 1 to E 5 according to the -invention and those of Comparison Examples C 1 to C 7 are set out in the following Table, reflecting the superior effect of added perborates (E l to E 4): although sodium perborate (E
5) formed in ~itu leads to substantially the same gold yield as H202, the consumption of NaCN could be reduced.
,, : . ,~ . ~, -- ~
:, -
Claims (10)
1. A process for leaching gold and silver from ores, ore concentrates and waste material from previous incomplete leachings by grinding of the material to be leached in the presence of a cyanide-containing leaching solution which has a pH value of 8 to 13 and which contains a peroxo compound, wherein at least one peroxoborate compound is present as the peroxo compound.
2. The process of claim 1, wherein the peroxoborate compound is present in solution or in very finely divided form.
3. The process of claim 2, wherein the peroxoborate compound is present in total from the start of the leaching process, or is introduced periodically during the process, or is formed in situ.
4. The process of claim 2, wherein the peroxoborate is selected from an akali metal peroxoborate, an alkaline earth metal peroxoborate and a mixture thereof.
5. The process of claim 2, wherein the peroxoborate is selected from sodium perborate mono- and tetrahydrate, calcium perborate, a superoxidized perborate and a mixture thereof.
6. The process of claim 1, wherein the pH is 9 to 12.
7. The process of claim 1, wherein the leaching solution contains from 0.005 to 2.5 weight percent cyanide, expressed as CN.
8. The process of claim 1, wherein the leaching solution contains from 0.02 to 2 weight percent cyanide, expressed as CN.
9. The process of any one of claims 1 to 8, wherein one to 100 equivalents of peroxoborate, expressed as BO3, are used per t of material to be leached.
10. The process of any one of claims 1 to 8, wherein 10 to 60 equivalents of peroxoborate, expressed as BO3, are used per t of material to be leached.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4114514A DE4114514A1 (en) | 1991-05-03 | 1991-05-03 | METHOD FOR THE LOWING OF GOLD AND SILVER |
| DEP4114514.3 | 1991-05-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2067841A1 true CA2067841A1 (en) | 1992-11-04 |
Family
ID=6430935
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002067841A Abandoned CA2067841A1 (en) | 1991-05-03 | 1992-05-01 | Process for leaching gold and silver |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0512247B1 (en) |
| AT (1) | ATE134712T1 (en) |
| AU (1) | AU642087B2 (en) |
| BR (1) | BR9201586A (en) |
| CA (1) | CA2067841A1 (en) |
| DE (2) | DE4114514A1 (en) |
| ES (1) | ES2084203T3 (en) |
| ZA (1) | ZA923190B (en) |
| ZW (1) | ZW4892A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19829274C2 (en) * | 1998-07-01 | 2002-06-20 | Otb Oberflaechentechnik Berlin | Process for the recovery of precious metals |
| DE102020209880A1 (en) | 2020-08-05 | 2022-02-10 | Robert Bosch Gesellschaft mit beschränkter Haftung | Process for the extraction of at least one precious metal |
| DE102020209884A1 (en) | 2020-08-05 | 2022-02-10 | Robert Bosch Gesellschaft mit beschränkter Haftung | Method of extracting gold |
| DE102020209885A1 (en) | 2020-08-05 | 2022-02-10 | Robert Bosch Gesellschaft mit beschränkter Haftung | Ball mill and process for extracting gold and/or silver and/or at least one platinum group metal |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU587850B2 (en) * | 1985-08-26 | 1989-08-31 | Bendigo Gold Associates Pty. Ltd. | A method of pre-treating an ore with hot alkali to improve the recovery of metal valves |
| DE4017899C1 (en) * | 1990-06-02 | 1991-11-14 | Degussa Ag, 6000 Frankfurt, De | Extn. of silver and gold from ores - by contacting ore with aq. leaching soln. contg. cyanide in presence of peroxo:borate, and sepg. cyano complexes formed |
-
1991
- 1991-05-03 DE DE4114514A patent/DE4114514A1/en not_active Withdrawn
-
1992
- 1992-03-27 ZW ZW48/92A patent/ZW4892A1/en unknown
- 1992-04-01 AT AT92105566T patent/ATE134712T1/en not_active IP Right Cessation
- 1992-04-01 ES ES92105566T patent/ES2084203T3/en not_active Expired - Lifetime
- 1992-04-01 EP EP92105566A patent/EP0512247B1/en not_active Expired - Lifetime
- 1992-04-01 DE DE59205427T patent/DE59205427D1/en not_active Expired - Fee Related
- 1992-04-29 BR BR929201586A patent/BR9201586A/en not_active Application Discontinuation
- 1992-04-30 ZA ZA923190A patent/ZA923190B/en unknown
- 1992-05-01 CA CA002067841A patent/CA2067841A1/en not_active Abandoned
- 1992-05-01 AU AU15960/92A patent/AU642087B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| AU1596092A (en) | 1992-11-05 |
| EP0512247A3 (en) | 1993-05-05 |
| BR9201586A (en) | 1992-12-15 |
| EP0512247B1 (en) | 1996-02-28 |
| ATE134712T1 (en) | 1996-03-15 |
| DE4114514A1 (en) | 1992-11-05 |
| AU642087B2 (en) | 1993-10-07 |
| ES2084203T3 (en) | 1996-05-01 |
| ZA923190B (en) | 1993-01-27 |
| ZW4892A1 (en) | 1993-02-17 |
| EP0512247A2 (en) | 1992-11-11 |
| DE59205427D1 (en) | 1996-04-04 |
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