AU627603B2 - A method for gold recovery using chlorine dioxide solution - Google Patents
A method for gold recovery using chlorine dioxide solution Download PDFInfo
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- AU627603B2 AU627603B2 AU59097/90A AU5909790A AU627603B2 AU 627603 B2 AU627603 B2 AU 627603B2 AU 59097/90 A AU59097/90 A AU 59097/90A AU 5909790 A AU5909790 A AU 5909790A AU 627603 B2 AU627603 B2 AU 627603B2
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- Australia
- Prior art keywords
- chlorine dioxide
- ore
- solution
- metal
- gold
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- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 title claims description 128
- 238000000034 method Methods 0.000 title claims description 77
- 239000004155 Chlorine dioxide Substances 0.000 title claims description 64
- 235000019398 chlorine dioxide Nutrition 0.000 title claims description 64
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims description 50
- 229910052737 gold Inorganic materials 0.000 title claims description 50
- 239000010931 gold Substances 0.000 title claims description 50
- 238000011084 recovery Methods 0.000 title claims description 32
- 229910052751 metal Inorganic materials 0.000 claims description 41
- 239000002184 metal Substances 0.000 claims description 41
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims description 32
- 238000002386 leaching Methods 0.000 claims description 28
- 150000002739 metals Chemical class 0.000 claims description 21
- 239000002002 slurry Substances 0.000 claims description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 239000003795 chemical substances by application Substances 0.000 claims description 9
- 238000000227 grinding Methods 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 5
- 230000006872 improvement Effects 0.000 claims description 2
- 230000003381 solubilizing effect Effects 0.000 claims 1
- 230000008569 process Effects 0.000 description 32
- 239000000243 solution Substances 0.000 description 28
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 22
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 14
- 229910052709 silver Inorganic materials 0.000 description 13
- 239000004332 silver Substances 0.000 description 13
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 11
- BZSXEZOLBIJVQK-UHFFFAOYSA-N 2-methylsulfonylbenzoic acid Chemical compound CS(=O)(=O)C1=CC=CC=C1C(O)=O BZSXEZOLBIJVQK-UHFFFAOYSA-N 0.000 description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 10
- UKLNMMHNWFDKNT-UHFFFAOYSA-M sodium chlorite Chemical compound [Na+].[O-]Cl=O UKLNMMHNWFDKNT-UHFFFAOYSA-M 0.000 description 10
- 229960002218 sodium chlorite Drugs 0.000 description 10
- 230000003647 oxidation Effects 0.000 description 9
- 238000007254 oxidation reaction Methods 0.000 description 9
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 description 7
- 239000012535 impurity Substances 0.000 description 7
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 6
- 239000000460 chlorine Substances 0.000 description 6
- 229910052801 chlorine Inorganic materials 0.000 description 6
- 238000005363 electrowinning Methods 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 230000007613 environmental effect Effects 0.000 description 4
- FDWREHZXQUYJFJ-UHFFFAOYSA-M gold monochloride Chemical compound [Cl-].[Au+] FDWREHZXQUYJFJ-UHFFFAOYSA-M 0.000 description 4
- 238000005342 ion exchange Methods 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 230000035484 reaction time Effects 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 4
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 239000010953 base metal Substances 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000003518 caustics Substances 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- IZLAVFWQHMDDGK-UHFFFAOYSA-N gold(1+);cyanide Chemical compound [Au+].N#[C-] IZLAVFWQHMDDGK-UHFFFAOYSA-N 0.000 description 3
- 239000003456 ion exchange resin Substances 0.000 description 3
- 229920003303 ion-exchange polymer Polymers 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 235000010269 sulphur dioxide Nutrition 0.000 description 3
- 150000003568 thioethers Chemical class 0.000 description 3
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 239000005708 Sodium hypochlorite Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 229910052787 antimony Inorganic materials 0.000 description 2
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 2
- 238000003556 assay Methods 0.000 description 2
- 239000003637 basic solution Substances 0.000 description 2
- 229920001429 chelating resin Polymers 0.000 description 2
- 238000001311 chemical methods and process Methods 0.000 description 2
- 238000005660 chlorination reaction Methods 0.000 description 2
- 229940060038 chlorine Drugs 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229960000443 hydrochloric acid Drugs 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- WDLWHQDACQUCJR-ZAMMOSSLSA-N (6r,7r)-7-[[(2r)-2-azaniumyl-2-(4-hydroxyphenyl)acetyl]amino]-8-oxo-3-[(e)-prop-1-enyl]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate Chemical compound C1([C@@H](N)C(=O)N[C@H]2[C@@H]3N(C2=O)C(=C(CS3)/C=C/C)C(O)=O)=CC=C(O)C=C1 WDLWHQDACQUCJR-ZAMMOSSLSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 244000002627 Eucalipto Species 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 101150012695 Procr gene Proteins 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- 208000013201 Stress fracture Diseases 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000001580 bacterial effect Effects 0.000 description 1
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000010908 decantation Methods 0.000 description 1
- MXCPYJZDGPQDRA-UHFFFAOYSA-N dialuminum;2-acetyloxybenzoic acid;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3].CC(=O)OC1=CC=CC=C1C(O)=O MXCPYJZDGPQDRA-UHFFFAOYSA-N 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- PQTCMBYFWMFIGM-UHFFFAOYSA-N gold silver Chemical compound [Ag].[Au] PQTCMBYFWMFIGM-UHFFFAOYSA-N 0.000 description 1
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical class Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000010297 mechanical methods and process Methods 0.000 description 1
- 230000005226 mechanical processes and functions Effects 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000005185 salting out Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- -1 silver metals Chemical class 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 229960005076 sodium hypochlorite Drugs 0.000 description 1
- 229940032330 sulfuric acid Drugs 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 239000004291 sulphur dioxide Substances 0.000 description 1
- 125000000101 thioether group Chemical group 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Classifications
-
- 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
Landscapes
- Manufacture And Refinement Of Metals (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
- Treating Waste Gases (AREA)
Description
r COMMONrWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION NAME ADDRESS OF APPLICANT: Rio Linda Chemical Co., Inc.
410 North 10th Street Sacramento California 95814 United States of America Geevor del Ecuador C.A.
Calle Los Eucaliptos 9/N Y Panamerican Norte Km 5 1/2 Quito Ecuador NAME(S) OF INVENTOR(S); John Y. MASON James A. WASAS Manfred K. FELGENHAUER Dale E. LYMAN ADDRESS FOR SERVICE: DAVIES COLLISON S, Patent Attorneys Little Collins Street, Melbourne, 3000.j l COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: H A method for gold recovery using chlorine dioxide solution C, 4 4t The following statement is a full description of this invention, including the best method of performing it known to me/us:- A METHOD FOR GOLD RECOVERY USING CHLORINE DIOXIDE SOLUTION BACKGROUND OF THE INVENTION The present invention is directed to the recovery of gold, silver and other oxidizable metals from naturally occurring sulfide and oxide ores. The present invention is particularly useful in ores containing refractory sulfides, carbonaceous matter, or which are difficult to process by the methods of prior art.
The present invention replaces the current practice of using sodium cyanide solutions with an ecologically and o economically more advantageous method.
o 00.
0 0 e o Although the present invention is expected to have wide o 00 S:O applicability in the processing of metal ores in view of its ecological and'economic advantages, initially it is expected to have greatest impact on the way refractory sulfide-containing ores are processed for recovery of gold and silver.
Furthermore, it is easily envisioned that the current invention can be used to treat ores containing oxidizable or carboneous impurities that interfere with the current practice of leaching with a sodium cyanide solution. These are prima',ly oxide ores.
Current practice in the mining industry for the extraction 1A I0,^ cc <kel 14 1& I y- Ci--Y l i of gold and silver from refractory sulfide ores is a two step process. The first step uses thermal roasting, pressure oxidation, or bacterial oxidation to chemically break down the sulfides in ground ore slurrys and concentrates. This pretreatment step oxidizes sulfide impurities to sulfur dioxide and/or sulfates exposing the microscopic gold particles for the cyanide leach step tthat follows. When thermal roasting or pressure oxidation is used, the reaction is generally stoichiometric for the sulfide impurities in the ore.
Chlorination is commonly used in current practice to remove carbonaceous impurities from oxide ores. The usage of chlorine is sufficient to remove most, or all, of the carbonaceous impurities.
I) I It
~I
ii tl The second step, leaching the pretreated ore with a dilute sodium cyanide solution, converts the gold into a soluble gold cyanide complex from which it can be recovered by any one of a number of commercially practiced processes including precipitation, carbon adsorption, and electrowinning.
In one embodiment of prior art, a sulfide ore slurry is placed in a large autoclave where steam, oxygen, and sometimes sulfuric acid is forced through the ore to oxidize sulfide impurities. This method called "pressure oxidation" may require several hours of processing time. The oxidation pretreatment is followed by neutralization with lime, then by addition of a basic solution of sodium cyanide as the primary leaching agent. The resulting soluble gold cyanide complex is Cc- ,ItQ"i
II
ii *4-4 04 #4 4 0 0 0 40 4 *4 44 0 o 4 4 4*4 p treated by carbon adsorption, precipitation, or electrowinning for gold silver recovery. This method does not releasa the copper, antimony, and base metals that may be present.
In a modification of this method, oxide ore containing little or no sulf ide impurity is piled in a mound ("heap") up to 200 feet high, in an area wh~.ch can be many acres in size.
Sodium cyanide solution is then distributed evenly over the heap during a period of weeks to months from sprinklers or emitters, not unlike lawnm sprinklers or emitters. The sodium cyanide solution percolates down through the heap, dissolving the gold as a gold cyanide complex, and is collected in usually open lined ponds. Gold is then recovered by the usual processes discussed above. This method is called a "heap leach" process. Although it is an economical one-step leaching process for oxide ores, the open cyanid~e ponds involve a degree of environmental and ecological risk..
With the changing view concerning ecology, the degree of risk in prior art methods can be unacceptable especially in ecologically sensitive areas. That is, the use of pressure oxidation or thermal roasting followed by a cyanide leach method is considered to be disadvantages because of the risk of cyanide contamination and sulfur dioxide emissions.
Furthermore, from a economic point of view, it is difficult to attain a high recovery of the gold (which is entrapped usually in the form of microscopic particles) from, refractoty sul1fide ores using current technology. Often, recoveries of 70 to 44 4 4 3 0 40 3 4 4 3 4*40 3 4 4 4 4 44 4404 *4 0 *414
C
I
04 4 044 #440 4 04 0 44 0 4 o 0444 00 00 4 00 00 4 00 0 "4 0 00 0 0 00 0 0 0 4444 00 4 40 04 00 4 00 0 004 0 44 4 0 0 0 0 04 0 0 are considered excellent, especially for low quality refractory sulfide ores. Many low quality ores, sulfide and oxide ores included, cannot be economically processed at such low recovery levels. Coupled with the difficulties of treating or disposing of cyanide containing tailings, especially in ecologically sensitive areas, it is clear that new methods of gold recovery are desirable to replace the known cyanide method.
One embodiment of the present invention uses a one-step leaching process employing chlorine dioxide to free the entrapped gold, silver, and other metals, and complex the metals into solution. It can be practiced in relatively small plants using static mixers, agitated tanks, or, possibly, vat or heap leach methods. Gold is converted into a soluble gold chloride complex which can be recovered using ion exchange resin, precipitation, electrowinning, or other methods for the removal of water and salting out the gold.
Although an exhaustive study has not been made to fully characterize the manner in which the present invention operates, it is believed that the chlorine dioxide attacks the sulfide ore stress fractures and fissures to break the sulfide structure into small and possibly colloidal size particles.
This action releases microscopic particles of gold which are entrapped within the sulfidi3 structure for further reaction with chlorine dioxide to form a soluble gold chloride complex.
other, less noble metals such as copper, antimony, and other base metals contained in the ore form soluble chlorides.
ij ii ii iii Ii i~t The only metal recovery process of which applicants are aware which uses chlorine dioxide is a process for vanadium recovery described in British Patent Application GB 2155917.
The method described therein involves the removal and recovery of vanadium, from a vanadium bearing material, using a caustic solution as the leaching agent. This is basically different from the present invention which uses chlorine dioxide as a leaching agent.
To enhance the leaching process, the British patent application teaches the use of a "leaching promotor" in the caustic leaching solution. The leaching promotor is selected from the group consisting of an ionic form of vanadium; hypochlorites of sodium, calcium and potassium; peroxides; chlorine dioxide and mixtures thereof. By contrast, as will be discussed below, the present invention involves contracting the ore with a chlorine dioxide solution to free gold and silver from a sulfide or oxide ore matrix and to oxidize gold and silver to a soluble oxidation state. The result is a solution which is neutral or acidic. The chlorine dioxide is the leaching agent. A caustic leaching agent is not used. Thus, the procef is substantially different in principle of operati' as well as in practice.
A first embodiment of the present invention is a one-step process for treating ores for the recovery of metals which can be leached with chlorine dioxide. in particular, the present invention provides a method for recovering gold and silver from ores containing carbonaceous materials and from sulfide ores.
In particular the invention can be applied to low quality, refractory sulfide ores without the need for pretreatment, or the use of ecologically undesirable cyanide.
As will be evident from the detailed description, the first embodiment of the present invention is useful for leaching a variety of metals which are solubilized with chlorine dioxide. In addition chlorine dioxide is also highly effective for releasing metals from sulfide ores in general.
"p y 44 44 4 44 44 4 4 4 44 44 444 4 In accordance with the present invention, the ores are crushed or ground, and in one embodiment, a slurry in water is formed from the ores. Chlorine dioxide, normally in aqueous solution, is then passed through the ore slurry in a reaction which appears to be complete in less than thirty minutes at room temperature. The gold (and other metals), now in the form of a soluble gold chloride complex, can be separated from the spent ore slurry by decantation or other known mechanical processes. In another embodiment chlorine gas is passed through the soluble gold chloride solution to maintain an acidic solution and reduce the usage of chlorine dioxide which is more expensive. This practice can also-contribute to high gold recovery values.
The metal is then recovered from solution by a known 4 4' 4 44 44 I, 4.4 '~0 4- 4,, c~ NvV~ method such as ion exchange, carbon adsorption, electrowinning or precipitation.
Because of the high efficiency with which chlorine dioxide breaks the sulfide matrix, it can be used to advantage in releasing metals other than gold and silver. A broad range of metals can be released by chlorine dioxide for recovery by other-methods. This single step process can also be applied to heap leach operations by substituting chlorine dioxide solution for the present practice of using sodium cyanide solution.
As compared with the prior art method of treating refractory sulfide ores to release gold and solubilize it for recovery, the present invention results in consistently high yields. More importantly, the present invention is a single i..t step process while the prior art requires a pretreatment step followed by a cyanide step in order to solubilize the gold.
:C:
a *The prior art single step, heap leach process involves large piles of ore over which cyanide solution is sprayed or emitted under ecologically difficult conditions and is not S successful with refractory sulfide ores. The present invention -does not use cyanide and is therefore ecologically preferable: chlorine dioxide has a history of usefulness for treatment of S' municipal water supplies and has been found ecologically safe.
From an economic point of view, the present invention can provide high processing efficiencies with relatively small 4 7 a plants because of the short ore contact time required, and can eliminate the environmental and ecological risk associated with cyanide containing ponds and tailings piles.
DETAILED DESCRIPTIOH OF THE INVENTION The present invention has application in the recovery of gold, silver, and other metals forming soluble chlorides from high sulfide, ores. It also has applicability for recovering other metals from ores where the cyanide process or other process using ecologically unacceptable agents are now practiced. Furthermore, it can be used to release metals from ores to increase recovery yields of metals in processes wherein chlorine dioxide is not presently used as the leaching agent.
V. By way of example, the processing of gold ore will be o 00 described in detail.
Preparatory to the recovery of metals in ores, it is usual o~to crush or to grind the ores for handling ease and to expose 0the metals. Thus, depending on the process to be applied, ore J o~is crushed or is further processed by grinding.
Typical ore crushing equipment now used iri treating ores, can crush ore down to about 1/4 inch (about 0. 6cm) pieces, op So~'~-sC~o ec" although much larger pieces) are usual. Crushed ore is used for heap leaching processes where rapid reaction or leaching times are not an important factor. Heap leaching procr aes, by their nature, can tolerate a wide range of ores sizes. However, the larger the average size, the longer the leaching time required.
Furthermore, the usual heap leaching processes, which do not use a pretreatment step to free metals from the ores, such as chlorination, oxidation and/or roasting, cannot be successfully applied to refractory sulfide ores.
Vat leaching processes can utilize a two step treatment and are applicable to refractory sulfide ores. For the vatleach process where rapid reaction times are important, the ore must be ground. Typical grinding equipment now in use in the field will grind ore down to about 400 mesh size. 100 mesh to 400 mesh grinding is normally accomplished without special procedures and this range is suitable for pumpable water slurrys.
1 0 ms'' The present invention leaching method can be applied to heap-leach or vat-leach analogous processes.
4 4 The heap-leach method can be essentially the same as it is now practiced. The improvement is to substitute a chlorine dioxide solution for the cyanide leaching solution normally used. For economic reasons, the chlorine dioxide solution, would normally be at the low end of useful concentration, normally 0.01% to 1% and preferably 0.05% to 0.3%.
A vat-leach analogous process can be practiced in a vat or in flow mixers or other smaller size equipment (compared to the huge piles used in heap-leaching). The usual grinding equipment can be used as a 100 to 400 mesh slurry will react sufficiently quickly for commercial operations. Although grinding to a smaller size is also suitable, the current cost of doing so does not provide any corresponding advantage.
Grinding to a significantly larger size than the 100 mesh would also work; however, as the size of the ore increases, the reaction time required for high gold recovery also increases.
With too large an ore size it may not be possible to accomplish the high recovery rates, which are possible even with low quality ores using the present invention. Higher concentrations of chlorine dioxide can be used and concentrations up to a saturated or supersaturated solution are contemplated. Lower concentrations of chlorine dioxide can be used but reaction times will be slower.
A slurry may be formed by mixing the ground ore with water. Typically a 10% to 65% by weight slurry is used.
Although higher solid concentrations can be used, pumping difficulties can be encountered. Using a slurry with much less than 10% solids results in dilution of the chlorine dioxide solution.
In small scale studies, it has been found that the reaction goes essenti lLly to completion within about one minute or less. For commercial, large-scale processing, it is expected that the reaction times of about 30 minutes or less will be used to insure that all of the slurry has had time to come in contact with the chlorine dioxide, except in heap leach operations where the volume of ore to be treated and larger ore pieces require longer times. However, vat reactors with residence times of less than 30 minutes are easily envisioned.
Static mixers can be used to obtain the necessary contact between the ore and chlorine dioxide, although agitated mixing equipment normally available in commercial installations is suitable. The reaction will proceed even in a pipe through which the slurry is pumped. It is only necessary that the chlorine dioxide solution come into intimate contact with the gold ore.
After treatment with chlorine dioxide, the water solution of gold and silver chloride complex is separated from the spent ore and the gold and silver is recovered therefrom.
Electrowinning or other methods can be used, including o00a precipitation and ion exchange. If recovery by ion-exchange resin is contemplated, chlorine gas can be percolated throVqi the gold bearing solution to adjust the pH and extend the useful life of the ion exchange resin. Recoveries of 70% to 80% are usual even with low quality ores.
EXAMPLES OF PREFERRED EMBODIMENTS A wide variety of chlorine dioxide-generating processes may be employed in the present invention. One class of such Cc- .4 ~~lrlLILY .i i i
N
ii
I
U
Bl_ processes is based on sodium chlorate, which is reacted with a reducing agent in the presence of a strong mineral acid, such as sulfuric acid, hydrochloric acid and phosphoric acid.
Another class of such processes is based on sodium chlorite, which is reacted with oxidizing agent and/or a strong mineral acid. Combinations of sodium chlorate and sodium chlorite also may be employed.
Specific examples of combinations of reactants which may be employed are sodium chlorate, sodium chloride and sulfuric acid, sodium chlorate and hydrochloric acid, (c) sodium chlorate, sodium chlorite, sodium chloride and sulfuric acid, sodium chlorate, sodium chlorite and hydrochloric acid, sodium chlorate, sulphur dioxide and sulfuric acid, sodium chlorate, methanol and sulfuric acid, sodium chlorite and chlorine, sodium chlorite and hydrochloric acid and/or sulfuric acid, sodium chlorite, oxidizing gas and sulfuric acid, sodium chlorate, sodium chloride, hydrogen peroxide and/or methanol and sulfuric acid, sodium chlorite, sodium hypochlorite and hydrochloric aid and/or sulfuric acid, and sodium chlorate, glucose and sulfuric acid. Other suitable combinations of reactants also may be employed.
According to the practice of the present invention, chlorine dioxide solution can be generated on-site by the process and apparatus described in Unites States patent numbers 4,292,292, "Chlorine Dioxide Generation Process"; 4,247,531, 12 1 13- "Chlorine Dioxide Generation Apparatus and Process"; and 4,590,057 "Process for the Generation of Chlorine Dioxide". In general the precursor reactants (chlorine and sodium chlorite or sodium hypochlorite, hydrochloric acid, and sodium chlorite) are vacuum educted into the generator reaction chamber wh-re gaseous chlorine dioxide is formed according to the following reactions: 2NaCIO 2 C1 2 -2C10 2 2NaCl (Two Chemical Process) 2NaC10 2 NaOC1 2HC1-2 C10 2 3NaCl H 2 0 (Three Chemical Process) The gaseous chlorine dioxide produced herein is immediately educted into a process water stream resulting in a chlorine dioxide solution of up to 10 gms. per liter concentration. Although a wide concentration range can be used, the preferred range of chlorine dioxide concentration for the present invention is 0.05% to the t 20 saturation point of chlorine dioxide in water. Such solutions are preferably used according to the invention such that at least 1kg of chlorine dioxide per metric ton of ore in the slurry, is reacted with the slurry.
25 Example 1. A high sulfide ore containing 10 gms/M ton gold and recoverable quantities of silver, platinum, copper, and base metals in a matrix containing 5.5% S" as s, ulfides and 0.8% CaMgCO 3 is treated with 5.5 kg/M ton chlorine dioxide for five minutes contact time. The gold 30 is recovered by ion exchange using Rohm Haas Amberlite IRA-900C resin.. Percent gold recovery by fire assay is 71%.
920521,wpftdisk78,59097, fax,13 -M Example 2. Same ore as in example 1. treated with kg/M ton chlorine dioxide plus 1.75 kg/M ton chlorine for five minutes contact time. The gold is recovered and analyzed as in example 1. gold recovery percentage is 86%.
Example 3. Same ore and conditions as example 2. with thirty minutes of contact time. 93% gold recovery is attained.
Example 4. An oxide ore containing less than 0.25% S° as sulfides and 8 gms/M ton gold is treated with 2.5 kg/M ton chlorine dioxide and 1.75 kg/M ton chlorine for 30 minutes contact time. The gold is recovered by ion exchange using Rohm Haas Amberlite IRA-900C resin and analyzed by fire assay.
The gold recovery rate is 100%.
3 i Although the present invention appears similar to the pretreatment accomplished in the prior art, it is clear that there are significant differences both in principle and in practice. The most significant difference is, of course, that the prior art requires a cyanidization step to solubilize the gold. This prior art second step must be accomplished in a basic solution of approximately pH 11 to avoid the release of highly toxic cyanide gas.
Another difference is that, when pretreatment is by thermal roasting or pressure oxidation, the reaction is stoichiometric for the conversion of sulfide to sulfate whereas the present invention, using chlorine dioxide, is not a 14
I
I 1 stoichiometric reaction. In a heap leaching embodiment, the use of chlorine dioxide provides high yields without the use of cyanide. Also, refractory sulfide ores can be successfully treated.
The above is illustrative of the preferred embodiment of 14 the present invention. Because of the value of gold, most of the work done to date is with gold and with silver which is a usual precious metal in coexistence with gold, in the ores normally processed. However, as is readily realized, the breaking of the sulfide ore matrix to rele:ase metals can be used to release any metals contained therein. Therefore, the use of ClO 2 to release mistals from the sulfide ores is not limited to gold and silver metals, The present invention, because of its sound environmental and ecological basis, is a highly useful process for recovery of metals from oxide or sulfide ores where present technology cannot be practiced because of environmental and legal restrictions.
Claims (19)
1. A method for treating sulfide ores for the recovering of a metal therefrom comprising reacting the 5 ore with chlorine dioxide thereby to release the metal.
2. The method of claim 1, wherein the chlorine dioxide is in a water solution further comprising grinding the ore and mixing it with water to form a slurry, and wherein the reacting step comprises mixing the slurry with the chlorine dioxide solution.
3. The method of claim 2, wherein the ore is ground to an average size of 100-400 mesh and the water slurry is formed by mixing water with 10-65% by weight of the ground ore; and the chlorine dioxide water solution is formed by dissolving at least 0.05% by weight chlorine dioxide in water.
4. The method of claim 3, wherein at least 1 kg of chlorine dioxide per metric ton of ore in the slurry, is reacted with the slurry.
The method of claim 1, further comprising recovering the released metal.
6. The method of claim 5, wherein the recovering of the released metal comprises solubilizing the metal and dissolving it into solution, and thereafter separating the metal from the solution.
7. The method of claim 6, wherein the chlorine dioxide solubilizes the metal.
8. The method of claim 7, wherein the metal is gold.
9. The method of claim 1, wherein the chlorine dioxide 92029,wpftdisk78,59097.fax,16 -i -17- is in a water solution, further comprising crushing the ore and piling it into a heap; and wherein the reacting step comprises percolating the chlorine dioxide solution through the heap.
The method of claim 9, wherein the ore is crushed to about 1/4 inch 6 inches (about 0.6 to
11. The method of claim 9. wherein the metal is solubilized by chlorine dioxide solution, further comprising collecting the solution percolated through the heap and recovering dissolved metal therefrom.
12. The method of claim 11, wherein the metal is gold.
13. In a heap leach method for treating sulfide ores for recovering of metals, wherein the ore is crushed and piled on a prepared surface, and wherein a leaching agent is percolated through the pile and collected for recovery of the metals dissolved therein, the improvement wherein sulfide ores as well as oxide ores can be treated and comprising using as the leaching agent a solution of chlorine dioxide. i i
14. A method of leaching a metal comprising reacting the metal with aqueous chlorine dioxide, to solubilize the metal and bring it into water solution.
The method of claim 14, wherein the metal is contained in an ore, comprising crushing or grinding the ore and contacting the ore with chlorine dioxide, in water solution.
16. The method of claim 15, wherein the chlorine dioxide is dissolved in water at a rate of at least 0.05% chlorine dioxide by weight, and thereafter the chlorine dioxide solution is reacted with the ore. CC 1 920522,wpftdisk78,59097.fax,17 -18-
17. A method for treating sulfide ores for the recovery of gold therefrom consisting essentially of reacting the ore with aqueous chlorine dioxide solution to solubilize the gold and form a solution; and recovering the gold from the solution.
18. The method of claim 17, wherein the chlorine dioxide solution contains 0.01% to 1% chlorine dioxide.
19. The method of claim 18, wherein the ore is reacted by forming it iiito a slurry in water, wherein the slurry contains 10% to 65% by weight of ore. A method for treating sulphide ores for the recovery of a metal therefrom substantially as hereinbefore described with reference to any one of the Examples. Dated this 22nd day of May 1992 RIO LINDA CHEMICAL CO., INC. and GEEVOR DEL ECUADOR C.A. By their Patent Attorneys DAVIES COLLISON CAVE 1 920522,wpftdisk78,59097- fax,18 i-'
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US40862589A | 1989-09-18 | 1989-09-18 | |
| US408625 | 1989-09-18 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU5909790A AU5909790A (en) | 1991-03-21 |
| AU627603B2 true AU627603B2 (en) | 1992-08-27 |
Family
ID=23617047
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU59097/90A Ceased AU627603B2 (en) | 1989-09-18 | 1990-07-18 | A method for gold recovery using chlorine dioxide solution |
Country Status (5)
| Country | Link |
|---|---|
| AU (1) | AU627603B2 (en) |
| BR (1) | BR9004585A (en) |
| CA (1) | CA2025116A1 (en) |
| MX (1) | MX170890B (en) |
| ZA (1) | ZA907281B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19626387C2 (en) * | 1996-07-01 | 2003-05-28 | Polysius Ag | Process for extracting metal from ore material |
| BR0317218A (en) * | 2002-12-31 | 2005-11-22 | Intec Ltd | Process for the recovery of a precious metal from a sulfuric material, process for the removal of a contaminant from a contaminated sulfuric material, process for the treatment of a contaminated sulfuric material and any metal |
| AU2002953566A0 (en) * | 2002-12-31 | 2003-01-16 | Intec Ltd | Removing contaminants from sulfidic materials |
| RU2444573C2 (en) * | 2010-01-20 | 2012-03-10 | Открытое акционерное общество "Кольская горно-металлургическая компания" | Manufacturing method of concentrate of precious metals from sulphide copper-nickel raw material |
| RU2613823C1 (en) * | 2015-12-18 | 2017-03-21 | Федеральное государственное бюджетное учреждение науки Институт химии и технологии редких элементов и минерального сырья им. И.В. Тананаева Кольского научного центра Российской академии наук (ИХТРЭМС КНЦ РАН) | Method for precious metals concentrate production from copper-nickel converter matte |
| CN114752780B (en) * | 2022-05-19 | 2024-04-26 | 昆明理工大学 | Method for increasing copper leaching rate in cuprite-type copper oxide ore by adding chlorine dioxide |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU5599890A (en) * | 1989-05-30 | 1990-12-06 | Exxon Chemical Patents Inc. | Process for recovery of precious metals from carbonaceous ores using chlorine dioxide |
-
1990
- 1990-07-18 AU AU59097/90A patent/AU627603B2/en not_active Ceased
- 1990-09-12 ZA ZA907281A patent/ZA907281B/en unknown
- 1990-09-12 CA CA002025116A patent/CA2025116A1/en not_active Abandoned
- 1990-09-13 BR BR909004585A patent/BR9004585A/en not_active Application Discontinuation
- 1990-09-18 MX MX022443A patent/MX170890B/en unknown
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU5599890A (en) * | 1989-05-30 | 1990-12-06 | Exxon Chemical Patents Inc. | Process for recovery of precious metals from carbonaceous ores using chlorine dioxide |
Also Published As
| Publication number | Publication date |
|---|---|
| ZA907281B (en) | 1991-10-30 |
| CA2025116A1 (en) | 1991-03-19 |
| BR9004585A (en) | 1991-09-10 |
| AU5909790A (en) | 1991-03-21 |
| MX170890B (en) | 1993-09-21 |
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