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Cobalt Recovery from Copper Leach Solutions

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Cobalt Recovery from Copper Leach Solutions PLEASE DO NOT RE , MOVE FROM LIBRA '. £ I'.] RY RI8927 , 2 n 27 % Bureau of Mines Report of Investigations/1985 Cobalt Recovery From Copper Leach Solutions By T. H. Jeffers and M. R. Harvey UNITED STATES DEPARTMENT OF THE INTERIOR r I Report of Investigations 8927 Cobalt Recovery From Copper Leach Solutions By T. H. Jeffers and M. R. Harvey UNITED STATES DEPARTMENT OF THE INTERIOR Donald Paul Hodel, Secretary BUREAU OF MINES Robert C. Horton, Director Library of Congress Cataloging in Publication Data: Jeffers, T. H. (Thomas H.) Cobalt recovery from copper leach solutions. (Report of investigations; 8927) Bibliography: p. 12. Supt. of Docs. no.: [28.23:8927. 1. Cobalt-Metallurgy., 2. Leaching. 3. Copper. 1. Harvey, M. R. (Malcolm R.). II. Title. III. Series: Report of investigations (United SUites. Bureau of Mines) ; 8927. TN23. U43 ['fN799. C6] 6228 [66H'. 733] 84·600288 " I l' CONTENTS Abstract .•••...••••...••..•••...••..•.•..•.... !t •••••••••••••••••••••••••••••• 1 Int roduc tion •••••••••• " ...................................................... 2 Description of the resource •••••••••••••••••••••••••••••••••••••••••••••••••• 3 Resin selection •••••••••••• I) ••••••••••••••••••••••••••••••••••••• It ••••••••••• 3 Process description •••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 4 Experimental results •••••••••••••••••••••• ~ •••••••••••••••••••••••••••••••••• 5 Ion exehange ••••••••••••••• it ••••••••••••••••••••••••••••••••••••••••••••••• 5 I Res in loading •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 5 I Selective impurity removal ••••••••••••••••••••••••••••••••••••••••••••••• 7 , Res in elution ............................................................ 7 ! Iron, zinc, and aluminum impurity removal •••••••••••••••••••••••••••• ,•••••• 7 ! Preliminary tea ts ........................................................ 8 D2EHPA semi continuous circuit •••••••••••••••••••••••••••••••••••••••••••• 8 Cobalt-nickel separation ••••••••••••••••••••••••••••••••••••••••••••••••••• 9 I Preliminary tes ts ........................................................ 9 Final iron and zinc impurity removal ••••••••••••••••••••••••••••••••••••• 10 Cyanex 272 semicontinuous circuit •••••••••••••••••••••••••••••••••••••••• 10 Summary and conclua ions ................................................................. 11 References •••••• " ............................................................. 12 ILLUSTRATIONS 1. Copper dump leaching with cobalt recovery circuit •••••••••••••••••••••• 3 2. Simplified flow diagram for cobalt and nickel recovery from copper processing solution ••••••••••••••••••••••••••••••••••••••••••••••••••••• 4 3. Typical two-stage cobalt extraction profile •••••••••••••••••••••••••••••• 6 TABLES 1. Loading and elution results using XFS-4195 in 4-ft-high columns ••••••••• 5 2. Metal extractions and resin loadings using various flow rates and solu­ tion volumes in 4-ft-high columns ••••••••••••••••••••••••••••••••••••••• 6 3. Selective elution of iron, zinc, and aluminum impurities ••••••••••••••••• 7 4. Process streams resulting from recovery of cobalt from copper leach solutions .••••.••••••••.••.••.•.••.•••••..••.•.••.•••.••••.••••.••• "'.... 11 UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT ft foot mg/L milligram per liter g gram min minute giL gram per liter mL milliliter gpm/ft 2 gallon per minute per mL/min milliliter per minute square foot pct percent h hour vol pct volume percent in inch Ib pound 'I' .1 COBALT RECOVERY FROM COPPER LEACH SOLUTIONS By T. H. JeHers 1 and M. R. Harvey 1 \ I I ABSTRACT Significant amounts of cobalt, a strategic and critical metal, are present in readily accessible spent copper leach solutions. For exam­ ple, recovery of cobalt at two major u.S. copper operations could pro­ duce about 1,300,000 lb Co annually, about 13 pct of domestic consump­ tion. However, techniques such as solvent extraction and precipitation have not proven cost effective in separating and recovering the cobalt from these low-grade domestic sources. The Bureau of Mines has devised a procedure using a chelating ion­ exchange resin to extract cobalt from a pH 3.0 copper leach solution containing 30 mg/L Co. Cyclic tests in 4-ft-high by 1-in-diam columns gave an average cobalt extraction of 95 pct when 65 bed volumes of solu­ tion were processed at a flow rate of 4 gpm/ft 2 of resin area. After an impurity scrub, eluates contained, in grams per liter, 0.4 Co, 0.2 Ni, <0.001 Cu, 1.3 Fe, 2.8 Zn, and 0.008 AI. Solvent extraction procedures to remove impurities, reject nickel, and concentrate cobalt produced a cobalt sulfate solution containing 80 g/L Co, 0.05 g/L Ni, and not more than 1 mg/L Cu, Fe, Zn, or AI. Based on data from commercial electro­ winning operations, this solution appears suitable for production of metallic cobalt. 'Chemical engineer, Salt Lake City Research Center, Bureau of Mines, Salt Lake City, UT. 2 INTRODUCTION Cobalt is a strategic and critical met­ Several processing schemes utilizing al because of its use in jet engines, solvent extraction and precipitation have tool steels, and catalysts. In many ap­ been developed for recovering cobalt from plications, substitution of other metals acidic sulfate solutions. Flett and West is not possible. Currently, the United (2) used di-2-ethylhexyl phosphoric acid States does not produce any primary co­ to extract cobalt from sulfate solutions, balt and depends entirely upon imported Ogata, Namihisa, and Fujii (3) used 2- supplies and a small recycling industry. ethylhexyl hydrogen 2-ethYlhexylphosphon­ In 1982, the United States imported about ate. Solvent extraction of cobalt using 90 pct of its cobalt supply, much of it these or other reagents for the copper from Africa (l).2 leach streams would not be effective be­ cause of poor selectivity and excessive Although domestic cobalt reserves are solvent losses incurred while extracting limited, significant amounts are present cobalt from very large volumes of solu­ in some copper leach solutions produced tion. Likewise, precipitation of cobalt by sulfuric acid leaching of low-grade directly from the acidic sulfate solu­ copper ores. The total quantity of co­ tions (4-5) would be ineffective owing balt available in these solutions is not to selectivity problems and filtration known, but cobalt recovery from two recy­ requirements. cle streams located at major U.s. copper operations could produce about 1,300,000 The Bureau of Mines has investigated lb of cobalt annually. This would sat­ ion-exchange cobalt recovery from copper isfy 13 pct of domestic consumption leach solutions. The process consists of and help relieve the need for imported ion exchange to extract cobalt from the cobalt. high-volume copper leach streams, result­ ing in small volumes of cobalt-rich elu­ Presently, cost-effective technology is ates. These eluates are then processed not available to separate and recover using solvent extraction to remove coex­ cobalt from these low-grade solutions. tracted impurities and to further concen­ The complex solutions contain copper, trate the cobalt. A cobalt sulfate solu­ nickel, iron, zinc, aluminum, magnesium, tion suitable for cobalt electrowinning manganese, and other elements, in add­ is produced. This process has signif­ ition to cobalt. Although significant icant advantages compared with processes amounts of cobalt may be recoverable, recovering cobalt from primary sources. cobalt solution concentrations are only Since the cobalt in the copper leach so­ 15 to 30 mg!L. Since economic consider­ lution has already been solubilized, the ations dictate that copper leach stream often difficult and expensive dissolution i flows of several thousand gallons per step is avoided. Also, existing support minute must be processed, pH and temper­ facilities are available, and thus the ature adjustments would not be practical. initial capital investment for site de­ Also, the addition of reagents to the velopment would be minimal. streams to enhance cobalt extraction would be costly and could affect affili­ Only very limited studies have pre­ ated leaching and copper recovery viously been conducted using ion exchang­ operations. ers for cobalt-bearing solutions (6). These ion-exchange resins were generally unacceptable for use with dilute copper 2underlined numbers in parentheses re­ leach solutions because of their poor fer to items in the list of references at selectivity for cobalt and low cobalt the end of this report. loadings. 3 DESCRIPTION OF THE RESOURCE Solutions from two copper leaching op­ downward through the are, leaching out erations were studied; one contained 30 materials that accumulated in the solu­ mg/L Co and the other 15 mg/L Co. The tion. This leach liquor was then col­ 30-mg/L solution, used in the majority of lected in a reservoir and processed using the semicontinuous testing, was copper cementation with scrap iron to remove cementation plant effluent containing, in most of the copper. At this point, solu­ grams per liter, 0.03 Co, 0.035 Ni, 0.06 tion was removed for testing in the co­ Cu, 2.0 Fe, 0.2 Zn, 4.5 AI, 7.2 Mg, and balt recovery system. Because large 0.4 Mn. The solution pH was 3.0. amounts of solution were required in cer­ tain phases of the test program, synthet­ The copper leach solutions were produc­ ic solutions were sometimes used. How­ ed by dump leaching of low-grade ores ever, continual cross-checking showed with dilute sulfuric acid. A schematic similar test results regardless of wheth­ of this process is shown in figure
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