Source: http://www.google.com/patents/US7947108?dq=4316055
Timestamp: 2015-05-30 21:50:43
Document Index: 489619795

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 60', 'Application No. 60', 'art 1', 'art 1', 'art 2', 'art 2', 'art 3', 'art 3']

Patent US7947108 - Precious metal recovery using thiocyanate lixiviant - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsMineral materials comprising copper and precious metal are subjected to an acidic leach of the copper followed by an acidic thiocyanate leach of the precious metal....http://www.google.com/patents/US7947108?utm_source=gb-gplus-sharePatent US7947108 - Precious metal recovery using thiocyanate lixiviantAdvanced Patent SearchPublication numberUS7947108 B2Publication typeGrantApplication numberUS 12/476,084Publication dateMay 24, 2011Filing dateJun 1, 2009Priority dateApr 4, 2003Fee statusPaidAlso published asCA2520039A1, CA2520039C, CA2693271A1, CA2693271C, EP1629129A2, EP1629129A4, US7285256, US7537640, US7559973, US20040197249, US20080066577, US20080066578, US20090288521, WO2004092448A2, WO2004092448A3Publication number12476084, 476084, US 7947108 B2, US 7947108B2, US-B2-7947108, US7947108 B2, US7947108B2InventorsRong Yu Wan, K. Marc LeVierOriginal AssigneeNewmont Usa LimitedExport CitationBiBTeX, EndNote, RefManPatent Citations (41), Non-Patent Citations (14), Classifications (12), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetPrecious metal recovery using thiocyanate lixiviant
US 7947108 B2Abstract
Mineral materials comprising copper and precious metal are subjected to an acidic leach of the copper followed by an acidic thiocyanate leach of the precious metal.
1. A method for removing copper and precious metal from a mineral material feed comprising copper and comprising precious metal locked in one or more sulfide mineral, the method comprising:
pressure oxidizing the mineral material feed in particulate form slurried in an aqueous liquid to decompose at least a portion of the sulfide mineral, the pressure oxidizing comprising dissolving at least a majority of the copper of the mineral material feed into the aqueous liquid;
recovering from the pressure oxidizing solid residue and acidic liquid effluent, the solid residue comprising at least a portion of the precious metal from the mineral material feed, the liquid effluent comprising in solution at least a majority of the copper of the mineral material feed;
thiocyanate leaching at least a portion of the solid residue with an acidic thiocyanate leach solution to dissolve into the thiocyanate leach solution in the form of precious metal-hiocyanate complex at least a portion of the precious metal from the solid residue; and
separating from the liquid effluent and recovering in a purified copper-containing product at least a majority of the copper dissolved in the liquid effluent;
wherein feed of the thiocyanate leach solution to the thiocyanate leaching comprises dissolved ferric iron and a molar ratio of the dissolved ferric iron to the dissolved thiocyanate of at least 2.
2. The method of claim 1, wherein the feed of the thiocyanate leach solution has a pH in a range of from pH 1 to pH 3 and the feed of the thiocyanate leach solution comprises from 0.0001 to 0.05 mole per liter of the dissolved thiocyanate and at least 0.05 mole per liter of the dissolved ferric iron.
3. The method of claim 2, wherein the ratio of the dissolved ferric iron to the dissolved thiocyanate is at least 7.
4. The method of claim 2, wherein the feed of the thiocyanate leach solution comprises not more that 0.03 mole per liter of the dissolved thiocyanate.
5. A method for removing copper and precious metal from a mineral material feed comprising copper and comprising precious metal locked in one or more sulfide mineral, the method comprising:
thiocyanate leaching at least a portion of the solid residue with an acidic thiocyanate leach solution to dissolve into the thiocyanate leach solution in the form of precious metal-thiocyanate complex at least a portion of the precious metal from the solid residue; and
the pressure oxidizing is conducted at a temperature of at least 160� C. and oxygen gas over pressure of at least 10 psi;
the feed of the thiocyanate leach solution has a pH in a range of from pH 1 to pH 3 and the feed of the thiocyanate leach solution comprises of from 0.005 to 0.05 mole per liter of the dissolved thiocyanate;
the mineral material feed comprises at least 3 weight percent sulfide sulfur and at least 0.1 weight percent of the copper;
the precious metal comprises gold and during the thiocyanate leaching, a majority of the gold is dissolved into the thiocyanate leach solution in the form of precious metal-thiocyanate complex; and the recovering comprises solvent extraction from the liquid effluent of a majority of the copper dissolved in the liquid effluent.
6. The method of claim 5, wherein the mineral material feed comprises at least 1 weight percent of the copper metal that dissolves into the aqueous liquid during the pressure oxidizing and that is thereafter separated from the liquid effluent during the separating.
7. The method of claim 5, wherein the mineral material feed comprises at least 2 weight percent sulfide sulfur.
8. The method of claim 5, wherein the mineral material feed comprises at least 3 weight percent sulfide sulfur.
9. The method of claim 8, wherein the mineral material feed comprises a sulfide concentrate.
10. The method of claim 5, wherein the mineral material feed comprises at least 5 weight percent of the copper that dissolves into the aqueous liquid during the pressure oxidizing and that is thereafter separated from the liquid effluent during the separating.
11. The method of claim 5, wherein the separating comprises solvent extraction of copper from the liquid effluent.
12. The method of claim 5, wherein the precious metal comprises gold; and
the thiocyanate leaching comprises dissolving into the thiocyanate leach solution at least a majority of the gold from the solid residue.
13. The method of claim 5, wherein feed of the thiocyanate leach solution to the thiocyanate leaching comprises dissolved ferric iron and a molar ratio of the dissolved ferric iron to the dissolved thiocyanate of at least 2.
14. The method of claim 13, wherein the feed of the thiocyanate leach solution comprises at least 0.05 mole per liter of the dissolved ferric iron.
This application is a divisional of U.S. patent application Ser. No. 11/868,378 entitled “PRECIOUS METAL RECOVERY USING THIOCYANATE LIXIVIANT” filed Oct. 5, 2007, now U.S. Pat. No. 7,559,973, which is a divisional of U.S. patent application Ser. No. 10/651,184 by Wan et al. entitled “PRECIOUS METAL RECOVERY USING THIOCYANATE LIXIVIANT” filed Aug. 28, 2003, now U.S. Pat. No. 7,285,256, which claims a priority benefit to U.S. Provisional Patent Application No. 60/470,045 by Wan et al. entitled “PRECIOUS METAL RECOVERY USING THIOCYANATE LIXIVIANT” filed May 12, 2003 and to U.S. Provisional Patent Application No. 60/460,795 by Wan et al. entitled “PRECIOUS METAL RECOVERY USING THIOCYANATE LIXIVIANT” filed Apr. 4, 2003; and each and every portion of the contents of each of the aforementioned U.S. patent application Ser. No. 11/868,378, U.S. patent application Ser. No. 10/651,184, U.S. Provisional Patent Application No. 60,470,045 and U.S. Provisional Patent Application No. 60/460,795 are incorporated by reference herein as if set forth herein in full.
Au+ Au(SCN)aq 1.86 � 1015 Au(SCN)2 − 1.45 � 1019 Au3+ Au(SCN)4 − 4.57 � 1043 Au(SCN)5 2− 4.17 � 1043 Au(SCN)6 3− 4.68 � 1043 For enhanced performance, the pH of the feed of the thiocyanate leach solution, as supplied to the thiocyanate leach, should be in an acidic range having a lower limit of pH 0.75, preferably pH 1 and more preferably pH 1.5 and having an upper limit of pH 3.5, preferably pH 3 and more preferably pH 2.5. One preferred range for the feed of the thiocyanate leach solution is from pH 1 to pH 3, with a pH of from 1.5 to pH 2.5 being more preferred. A pH of pH 2 is particularly preferred for the feed of the thiocyanate leach solution. In one possible process enhancement, the thiocyanate leach solution may be maintained within the noted acidic pH ranges throughout the thiocyanate leach, and preferably also during subsequent precious metal recovery operations. In another possible process enhancement, the feed of the thiocyanate leach solution may be carefully prepared to contain a high concentration of dissolved ferric iron relative to the concentration of dissolved thiocyanate. For this enhancement, the feed of the thiocyanate leach solution preferably has a molar ratio of dissolved ferric iron to dissolved thiocyanate (such ratio being sometimes referred to herein as [Fe3+]/[SCN]) of at least 2, more preferably at least 4, even more preferably at least 7, still more preferably at least 8 and most preferably at least 10. As yet a further possible enhancement, the molar ratio of the dissolved ferric iron to the dissolved thiocyanate may be maintained at a level that is not larger than 20. The molar ratio of the dissolved ferric iron to the dissolved thiocyanate may be determined by dividing the molar concentration of the dissolved ferric iron by the molar concentration of the dissolved thiocyanate. By molar concentration, it is meant the gram-moles (referred to herein simply as moles) of dissolved ferric iron or dissolved thiocyanate, as the case may be, per liter of solution (molar concentrations sometimes being designated herein with the abbreviated symbol “M”). As used herein, concentration refers to molar concentration unless specifically noted otherwise. As used herein, a concentration denoted as “ppm” refers to parts per million parts on a weight basis. As will be appreciated, the ratio of the molar concentrations of dissolved ferric iron to dissolved thiocyanate is also equal to the ratio of the total moles of the dissolved ferric iron to the total moles of dissolved thiocyanate in the leach solution. The ratio of molar concentrations of components and the ratio of total moles of the components are each often referred to herein simply as a “molar ratio” of the components.
In one aspect, the invention involves a method comprising acidic pretreatment of a mineral material feed prior to a thiocyanate leach. In one implementation the mineral material feed comprises preg-robbing organic carbon, and the acidic pretreatment involves oxidative treatment to decompose and/or passivate the organic carbon to reduce the preg-robbing capability of the mineral material. In another implementation, the mineral material feed comprises precious metal locked in sulfide minerals, such as might be the situation with refractory sulfide ores and concentrates, and the acidic pretreatment involves oxidative pretreatment to decompose sulfide minerals to release precious metal prior to the thiocyanate leach. In one implementation, oxidative pretreatment may include, for example, bio-oxidation or pressure oxidation of the mineral material feed. In another implementation, the mineral material feed may include a nonferrous, nonprecious metal (such as for example one or more of copper, nickel, zinc and lead) in sufficient quantity for economic recovery, and the acidic pretreatment may involve leaching the nonferrous nonprecious metal from the mineral material feed prior to the thiocyanate leach to extract precious metal. Leaching of the nonferrous nonprecious metal may also involve decomposition of sulfide minerals, such as for example, during bio-oxidation or pressure oxidation pretreatment to decompose sulfide minerals. In one implementation, the acidic pretreatment may involve acidic leaching of a component from the mineral material feed that would otherwise interfere with or complicate precious metal recovery using the thiocyanate leach. For example, when the mineral material feed includes appreciable soluble copper, the soluble copper may be removed in an acidic preleach, such as using an acidic sulfate leach solution. This implementation may be used, for example, to remove nuisance quantities of soluble copper from the mineral material feed prior to the thiocyanate leach of the precious metals, to recover by-product copper from precious metal ores or concentrates, or to permit by-product precious metal recovery following copper recovery from copper ores or concentrates, such as in a copper dump leach operations.
In one aspect, the invention involves preparation and/or conditioning of acidic thiocyanate leach solutions involving converting dissolved cyanide to dissolved thiocyanate in an acidic aqueous liquid. This implementation may be used, for example, to initially prepare a thiocyanate solution or to compensate for thiocyanate losses during thiocyanate leaching operations.
The present invention may be used to treat refractory sulfide gold ores, mildly refractory sulfide gold ores, and/or sulfide concentrates prepared from one or more of any such ores. As will be appreciated, a sulfide concentrate will contain a higher sulfide sulfur content than the ore(s) from which the concentrate is prepared. The sulfide sulfur content of the sulfide concentrate is often at least twice as large and more often several times as large as the sulfide sulfur content of the ore materials from which the concentrate is prepared. The present invention may also be used to treat refractory gold ores and concentrates comprising significant gold not amenable to recovery by direct cyanide leaching for reasons other than or in addition to gold being bound in sulfide mineralization, such as for example because of the presence of preg-robbing organic carbon.
Referring now to FIG. 3, a generalized process block diagram is shown for one implementation of the present invention for processing refractory gold ores, concentrates prepared from such refractory gold ores and/or other gold-bearing refractory mineral material comprising gold that is not amenable to recovery by direct cyanide leaching. Reference numerals are the same as those used in FIGS. 1 and 2, except as noted. As shown in FIG. 3, a refractory mineral material feed 128, typically in particulate form, is subjected to oxidative pretreatment 130. The refractory mineral material feed 128 could be refractory due to one or multiple characteristics of the mineral material feed. For example, the refractory mineral material feed 128 could be refractory because it comprises significant gold that is bound in sulfide minerals not amenable to gold recovery by direct cyanide leaching (refractory sulfide mineral material) and/or because the refractory mineral material feed 128 comprises preg-robbing organic carbon (refractory carbonaceous mineral material). A refractory sulfide mineral material feed may comprise preg-robbing organic carbon in addition to refractory sulfide mineral material. Likewise, a refractory carbonaceous mineral material feed may comprise refractory sulfide mineral material in addition to the preg-robbing organic carbon.
Preferably the concentration of dissolved ferric iron in the acidic effluent liquid 132 is at least twice as large (and more preferably at least four times as large) as the concentration of dissolved ferric iron in the feed of thiocyanate leach solution 106. Also, the acidic effluent liquid 132 may be substantially as produced during the oxidative pretreatment 132, or may result from treatment following production in the oxidative pretreatment 132. For example, the pH of the acidic effluent liquid 132 may be adjusted up or down as desired prior to being mixed with the thiocyanate leach solution. Also, the acidic effluent liquid 132 may be a more concentrated solution formed by removal of water, such as by evaporation, from a less concentrated solution produced during the oxidative pretreatment 130. When mixed with the thiocyanate leach solution during the leach solution conditioning 112, the acidic effluent liquid 132 preferably has a pH of no larger than pH 3 and preferably no larger than ph 2.5. In one variation, the acidic effluent liquid 132, when mixed with the thiocyanate leach solution during the leach solution conditioning 112, may have a pH of pH 2 or less or even pH 1.5 or less. In one variation, the acidic effluent liquid 132 has a pH in a range of from pH 0.1 to pH 3, and preferably in a range of from pH 1 to pH3, when added to the thiocyanate leach solution during the leach solution conditioning 112.
Alternatively, the soluble copper may be present in high enough quantities to be of economic value. The copper may represent the primary value in the ore (the gold being a by-product value) or the gold may represent the primary value in the ore (the copper being a by-product value).
SCN−+RNH2+H+=(RNH3 +�SCN−)
(RNH3 +�SCN−)+Au(SCN)2 −=(RNH3�Au(SCN)2 −)+SCN−
During the solvent extraction 192, the aqueous pregnant thiocyanate leach solution 108 is contacted with an organic liquid phase containing an extractant for gold-thiocyanate complex. Gold-thiocyanate complex is transferred from the pregnant thiocyanate leach solution 108 into the organic liquid phase. The organic liquid phase loaded with gold is separated from the thiocyanate leach solution, and the barren effluent of the thiocyanate leach solution 122 is supplied to the leach solution conditioning 112 for use to prepare the feed of the thiocyanate leach solution.
The transfer of gold from gold-thiocyanate complex to gold-cyanide complex during the complex transfer 200 may advantageously be accomplished in a preferred implementation of the invention by addition to the pregnant thiocyanate leach solution 108 of only a small quantity of dissolved cyanide. A stoichiometric quantity of cyanide required for complete complexation with the gold to from gold-cyanide complex is two moles of the cyanide group CN per mole of gold, assuming all gold is solubilized as the aurocyanide ion Au(CN)2 −. The disclosed cyanide may be introduced into the pregnant thiocyanate leach solution 108 in any suitable form, such as for example in the form of sodium or potassium cyanide. Moreover, the cyanide may be introduced into the pregnant thiocyanate leach solution 108 in any convenient manner, such as for example, by dissolving a cyanide reagent (e.g. sodium or potassium cyanide) into the pregnant thiocyanate solution 108, or (preferably) by adding to the pregnant thiocyanate leach solution 108 a small quantity of a pre-prepared, concentrated cyanide solution. Also, the quantity of the cyanide added to the pregnant thiocyanate leach solution 108 will typically be at a molar ratio of the added cyanide to precious metal (and preferably of the added cyanide to gold) of no larger than 20:1 (ten times a stoichiometric quantity), preferably no larger than 10:1 (5 times a stoichiometric quantity), more preferably no larger than 5:1 (2.5 times a stoichiometric quantity) and even more preferably no larger than 4:1 (two times a stoichiometric quantity). The quantity of added cyanide will typically be at a molar ratio of cyanide to precious metal (and preferably of the added cyanide to gold) of at least 2:1 (a stoichiometric quantity). Moreover, the cyanide will typically be added to the pregnant thiocyanate leach solution 108 in a quantity that is small in comparison to the amount of dissolved thiocyanate in the pregnant thiocyanate leach solution 108. The quantity of added cyanide will typically be at a molar ratio of cyanide to dissolved thiocyanate of no larger than 1:2, preferably no larger than 1:4, more preferably no larger than 1:5, even more preferably no larger than 1:7 and still more preferably no larger than 1:10.
In one preferred variation of the implementation of FIG. 13, rapid conversion of dissolved cyanide to dissolved thiocyanate is promoted during the conversion 214 by introducing appropriate reagent(s) into the aqueous liquid during the conversion 214. Preferred reagents for converting cyanide to thiocyanate include sulfide and hydrosulfide materials. Examples of possible reagents include sodium sulfide, sodium hydrosulfide, potassium sulfide, potassium hydrosulfide, ammonium sulfide, ammonium hydrosulfide and hydrogen sulfide. Other examples of possible reagents include sulfide minerals, such as for example pyrrohotite.
As another example, some or all of the conversion of cyanide to thiocyanate could occur during thiocyanate leaching, such as due to contact with sulfide minerals, such as pyrrohotite, present in the mineral material being leached. For example, referring again to FIG. 12, some or all of cyanide introduced into the thiocyanate leach solution for the complex transfer 200 could subsequently be converted to thiocyanate during the thiocyanate leach 104 by contact with sulfide minerals, such as for example pyrrohotite, in the mineral material 102.
Weight Ratio of Final
Solution to Ore
Tests are preformed on samples of a refractory sulfide gold ore from the Lone Tree mine. A 65.8 kg sample of ore crushed to 100% passing 2 inches (50.8 mm) is subjected to bio-oxidation pretreatment in a column having an inside diameter of 11 inches (279.4 mm), to simulate bio-oxidation in a heap. Prior to placing the ore in the column, 1920 mL of a mixed culture of acidophilic iron-oxidizing bacteria, containing Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, is mixed with the ore. During bio-oxidation a nutrient solution containing 0.4 g/L (NH4)2 SO4, 0.4 g/L MgSO4.7H2O and 0.04 g/L K2HPO4, is continuously recirculated through the ore in the column at a flow rate of about 6.5 mL/min. The column is continuously aerated from the base at an air flow rate of 28.3 L/h. The bio-oxidation pretreatment is continued for 258 days at room temperature (approximately 20-22� C.). Upon termination of the bio-oxidation pretreatment, the ore is removed from the column. During the bio-oxidation pretreatment, about 35% of the sulfide sulfur is oxidized. Representative assay information for the bio-oxidized ore is shown in Table 6.
During the thiocyanate leach tests, the bottles are open to the air and solution samples are taken at time intervals. The leaching lasts for a total of about 6 hours. Solution potential, pH values, and thiocyanate concentrations are measured. Gold is analyzed by atomic absorption spectrophotometry (AAS). To overcome matrix effects, all AAS calibration standards are diluted in solutions representative of the thiocyanate leach solutions used in the particular leach tests. For some tests, gold concentration is also determined by solvent extraction with di-isobutyl ketone (containing 1% Aliquat 336) and AAS analysis. Thiocyanate concentration is determined by Volhard titration, which determines the total SCN− concentration. Total iron concentration is determined by AAS and ferrous ion concentration is determined by titration with potassium permanganate (KMnO4) or potassium dichromate (K2Cr2O7) in the presence of sulfuric acid after complete precipitation of the thiocyanate ion. The solids residue from each thiocyanate leach test is washed thoroughly with water and dried prior to analysis of a representative sample for gold using fire assay followed by digestion and AAS.
0.05 (2.9) 0.2 (11.1)
0.05 (2.9) 0.1 (5.58)
0.05 (2.9) 0.3 (16.7)
Fe3+ to Fe2+, %
A refractory sulfide gold ore from the Lone Tree mine, of a type generally as described in Example 2, is bio-oxidized. Representative assay information for the bio-oxidized ore is shown in Table 12. A portion of the bio-oxidized ore is air dried and crushed to a size of minus 10 mesh (1.68 mm) for gold extraction testing.
A portion of the bio-oxidized ore of Example 4 is air dried and crushed to a size of minus 32.8 mm for gold extraction testing. After crushing, a 13.6 kg sample of the bio-oxidized ore is loaded into each of three columns. Each column has an inside diameter of 4 inches (101.6 mm). The bio-oxidized ore sample in each column is leached with either a cyanide leach solution or a thiocyanate leach solution to extract gold. For the cyanide leach test, the bio-oxidized ore sample is agglomerated with lime at 6 kg per tonne of ore sample prior to being loaded into the column. The amount of lime addition is determined based on neutralization tests performed on the same bio-oxidized ore. Thiocyanate leach solutions are prepared at a pH of about pH 2 with ferric sulfate and potassium thiocyanate dissolved in deionized water. The cyanide leach solution is prepared at a pH between 10.5 and 11 with 0.25 g/L sodium cyanide. Properties of the prepared leach solutions are summarized in Table 14.
[Fe 3+ +] M
For each test, leach solution is applied at a rate of about 9.8 L/hr-m2 to the top of the bio-oxidized ore samples in the columns from a reservoir of leach solution having an initial volume of 1900 mL. The test continues for 17 days.
Acidic synthetic thiocyanate solutions are prepared by dissolving potassium thiocyanate, ferric sulfate and gold in deionized water. Properties of the prepared thiocyanate solutions are summarized in Table 17. Two different organic liquid phases are prepared including Armeen™312 (Akzo Nobel) extractant. Armeen™312 is a tertiary amine (trilaurylamine) extractant. The first organic phase (O-1) is a solution of 0.05 M Armeen™312 in kerosene. The second organic phase (O-2) is a mixture of 0.9 part by volume of O-1 with 0.1 part by volume decanol (0.045 M Armeen™312).
Concentrated solutions of different amine extractants are obtained and organic liquid phases including the different extractants are prepared by diluting 0.2 part by volume of the concentrated solution as received with 0.8 part by volume of xylene. An aqueous pregnant thiocyanate solution is prepared by column leaching a sample of refractory sulfide gold ore that has been pretreated by bio-oxidation. The pregnant thiocyanate leach solution from the column leach contains 2.06 ppm dissolved gold, 899 ppm dissolved thiocyanate, and 6450 ppm total dissolved iron (with 290.4 ppm of the dissolved iron being ferrous iron), a pH of 1.5 and an E of 489 mV. The extractants tested are Alamine™336 (tertiary amine, tri-C8-C10-alkylamine, from Cognis), Amberlite™LA-2 (secondary amine, lauryl-tert-alkylamine, from Cognis), Armeen™ (primary amine, dodecylamine, from Akzo Nobel), and Armeen™312 (tertiary amine, trilaurylamine, from Akzo Nobel).
A sample of Purolite™600, (Purolite Company), a gel-type, strong anionic ion exchange resin is obtained and divided into two portions. Water is removed from one portion by vacuum filtration and the dry weight of the resin is determined to provide information concerning the moisture content of the wet resin. The wet resin contains about 65.72 weight percent resin and about 34.28 weight percent water. For each test, 480 mL of a pregnant thiocyanate solution is added to a 1 L flask along with 1 g of the Purolite™ 600 resin (containing about 0.6572 g ion exchange resin), and the contents of the flask are mixed by a magnetic stirrer. Thiocyanate leach solution samples of 20 mL each are removed from the flask at the end of 1 hour, 3 hours and 7 hours and analyzed. Tests are performed using different levels of gold loading in the pregnant thiocyanate solutions containing either approximately 0.02 M thiocyanate or approximately 0.05 M thiocyanate. Gold loading on the resin (based on dry resin weight) is determined at the end of 7 hours.
Initial Prepared
Thiocyanate Solution
[NaCN]:[Au]
[Au]ppm
[Fe2+] M
(1)grams activated carbon granules per liter of prepared thiocyanate solution
Fe2+ to Fe3+ Addition
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Moscow "Metallurgy" Publisher. 1991. pp. 242-245.13Monhemius et al. Leaching of Dominican gold ores in iodide-catalysed thiocyanate solutions. Transactions of the Institute of Mining and Metallurgy (Section C). 1995. vol. 104, pp. C117-124.14Munoz, GA et al. Noncyanide leaching of an auriferous pyrite ore from Ecuador. Minerals and Metallurgical Processing. 2000. vol. 17, No. 3. pp. 198-204.Classifications U.S. Classification75/743, 423/27, 75/744International ClassificationC22B11/08, C22B3/04, C22B15/00Cooperative ClassificationC22B15/0076, C22B11/08, C22B3/0098European ClassificationC22B11/08, C22B3/00D4, C22B15/00L2A6BLegal EventsDateCodeEventDescriptionOct 29, 2014FPAYFee paymentYear of fee payment: 4Jun 28, 2011CCCertificate of correctionJun 3, 2009ASAssignmentOwner name: NEWMONT USA LIMITED, COLORADOFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:WAN, RONG YU;LEVIER, K. MARC;REEL/FRAME:022775/0801Effective date: 20031203RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services