Patent Application
20140262815
The present invention relates, generally, to systems and methods for recovering metal values from metal-bearing materials, and more specifically, to systems and methods for recovering cobalt and other metal values.
Cobalt is an industrially important element that may be used in various catalysts, dyes, alloys, inks, battery additives, and other industrially beneficial products. Cobalt may be found in nature in a variety of forms and in a variety of ores. Cobalt containing ores include cobaltite, heterogenite (CoOOH), erythrite, glaucodot, and skutterudite. As found in nature, cobalt often exists in an oxidation state other than zero. For example, cobalt is often found in the form of cobalt II and cobalt III. Cobalt metal is commercially saleable, though purified forms of cobalt II and/or cobalt III, such as those in a salt form, are also commercially saleable.
In conventional processes, cobalt containing materials precipitated with magnesium oxide (MgO) and subsequently leached tend to be difficult to filter. In addition, large volumes of aqueous solution are typically employed. More efficient systems and methods for cobalt recovery would be commercially and industrially advantageous. In addition, it would be commercially and industrially advantageous to produce both cobalt metal and ionic cobalt.
Accordingly, the present invention provides systems and methods for metal value recovery, such as cobalt recovery. In various embodiments, a method is provided comprising producing a cobalt hydroxide bearing material, leaching the cobalt hydroxide bearing material to form a slurry, filtering the slurry to yield cobalt depleted solids and a cobalt bearing liquid phase, performing a solution extraction of the cobalt bearing liquid phase to yield a purified cobalt bearing liquid phase, conditioning a first portion of the purified cobalt bearing liquid phase to yield a conditioned cobalt bearing solution, and, electrowinning the conditioned cobalt bearing solution to yield cobalt metal.
Further areas of applicability will become apparent from the detailed description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present invention.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present invention, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements and wherein:
The following description is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. The description of specific examples indicated in various embodiments of the present invention are intended for purposes of illustration only and are not intended to limit the scope of the invention disclosed herein. Moreover, recitation of multiple embodiments having stated features is not intended to exclude other embodiments having additional features or other embodiments incorporating different combinations of the stated features.
Furthermore, the detailed description of various embodiments herein makes reference to the accompanying drawing figures, which show various embodiments by way of illustration. While the embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that logical and mechanical changes may be made without departing from the spirit and scope of the present invention. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, steps or functions recited in descriptions any method, system, or process, may be executed in any order and are not limited to the order presented. Moreover, any of the step or functions thereof may be outsourced to or performed by one or more third parties. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component may include a singular embodiment.
The present invention relates, generally, to systems and methods for recovering metal values from metal-bearing materials, and more specifically, to systems and methods for recovering cobalt. Various embodiments of the present invention provide a process for recovering cobalt using, among other things, a precipitation and filtration process. These improved systems and methods disclosed herein achieve an advancement in the art improving filtration, reducing acid volumes consumed, and improving recovery yields.
In particular, it has been discovered that a precipitation and filtration process, such as one using lime, tends to, in various embodiments, improve filtration of cobalt bearing materials, increase cobalt recovery yield, and/or allow for an upstream bleed that reduces solution volumes in other processes. The use of lime results in the formation of gypsum, which aids in filtering.
In conventional processes, cobalt containing materials precipitated with magnesium oxide (MgO) and subsequently leached tend to be difficult to filter. It has been found that gypsum added via lime as a precipitant in one of the process stages tends to act as a filtering aid without such negative effects.
In conventional systems, large volumes of liquor having low cobalt concentrations are processed in various metallurgical processes, such as ion exchanges and solution extraction. However, it has been found that by placing a bleed after a filtration process, solution volumes used in downstream processes may be reduced. Thus, metal recovery processes may act on lower volumes of solution than in previous systems. Accordingly, reagent cost and plant equipment cost tends to be lessened.
In addition, it has been discovered production of cobalt and ionic cobalt may be conducted using an integrated process. In that regard, recovery of cobalt and ionic cobalt may be performed concurrently, nearly concurrently, or combinations thereof, in a manner that expedites recovery from a given feed stock of cobalt bearing materials. Stated another way, an integrated approach to the production of cobalt and ionic cobalt reduces the time and resources associated with cobalt recovery. In various embodiments, integrated recovery is advantageously combined with a bleed after a filtration process. Such a configuration may, for example, reduce solution volumes in the electrolyte of an electrowinning cell.
In addition, it has been discovered that production of cobalt may be integrated with a primary leaching operation. While various embodiments of the present invention may be constructed and/or operated in any physical location, it is advantageous to operate various embodiments in close proximity to a primary metal leaching operation. A primary leaching process may comprise a leaching, process that is intended to liberate one or more metals from a metal bearing material. For example, in various embodiments, a primary leaching process comprises a leaching process to liberate copper and cobalt from a metal hearing material that comprises copper and cobalt. By operating in close proximity to a primary metal leaching operation, certain outputs of various embodiments may be forwarded to the primary leaching process. This allows metal content to be retained and further processed, decreasing net loss of metal, for example, by reducing the amount of metal sent to tails or residue.
With reference to
Cobalt bearing material 102 may be an ore (cobaltite, heterogenite (CoOOH), erythrite, glaucodot, skutterudite, other cobalt containing ores, and mixtures of cobalt containing ores with ores bearing other metal values), a concentrate, a process residue, an impure metal salt, a preprocessed cobalt bearing material, combinations thereof, or any other material from which cobalt values are present. Cobalt, whether in metal or ionic form, may be recovered from cobalt bearing material 102. In accordance with various embodiments of the present invention. Various aspects and embodiments of the present invention, however, prove especially advantageous in connection with the recovery of cobalt from a preprocessed cobalt bearing material. A preprocessed cobalt bearing material may comprise a material that has been subjected to a prior metallurgical process. For example, a metallurgical process may result in the formation of cobalt hydroxide Co(OH)2. Cobalt hydroxide may be formed by combining a cobalt bearing material with magnesium oxide (MgO) or lime. It should be appreciated that a preprocessed cobalt bearing material may contain various other constituents as impurities or coprecipitates, such as copper, zinc, manganese and/or nickel. In various embodiments, cobalt bearing material 102 comprises cobalt hydroxide. In various embodiments, cobalt bearing material 102 comprises cobalt hydroxide produced by addition of magnesium oxide to a material containing cobalt ions. In various embodiments, cobalt bearing material 102 comprises cobalt hydroxide produced by addition of lime to a material containing cobalt ions. In various embodiments, cobalt bearing material 102 comprises cobalt hydroxide produced by addition of lime or magnesium oxide. Cobalt produced using magnesium oxide is generally considered of greater quality than cobalt produced using lime, though various factors, including reagent costs, may affect the selection of an appropriate precipitating agent.
With continued reference to
In accordance with various embodiments, leaching may be conducted at any suitable pressure, temperature, and/or oxygen content. Leaching can employ one of a high temperature, a medium temperature, or a low temperature, combined with one of high pressure, or atmospheric pressure. Leaching may utilize conventional atmospheric or pressure leaching, for example, but not limited to, low, medium or high temperature pressure leaching. As used herein, the term “pressure leaching” refers to a cobalt leaching process in which a cobalt bearing material is contacted with an acidic or a basic solution and oxygen under conditions of elevated temperature and pressure. Medium or high temperature pressure leaching processes which are generally thought of as those processes operating under acidic conditions at temperatures from about 12.0° C. to about 190° C. or up to about 250° C.
Cobalt bearing leachate 105 may be directed to filtration 106. Filtration 106 may comprise any suitable filtration process. For example, vacuum filters such as a belt filter or disc filter may be used. In addition, pressure filters such as a plate and frame filter may be used.
Filtration 106 may separate the cobalt bearing leachate 105 into a solid phase and a liquid phase. The solid phase may be treated as residue. However, in various embodiments, the solid phase is sent to a primary leaching process. A primary leaching process may comprise a leaching process that is intended to liberate one or more metals from a metal bearing material. For example, in various embodiments, a primary leaching process comprises a leaching process to liberate copper and cobalt from a metal bearing material that comprises copper and cobalt. The liquid phase of cobalt bearing reactive processed material 105 comprises filtrate 107. Filtrate 107 is forwarded to solution extraction 108. Upstream bleed 122 is taken from filtrate 107.
In various embodiments, solution extraction 108 is configured to selectively extract impurities, as described in further detail herein. In various embodiments, solution extraction 108 comprises a liquid-liquid extraction. During solution extraction 108, impurities from the liquids phase may be loaded selectively into an organic phase in an extraction stage. Impurities may include one or more of copper, zinc, manganese and nickel. In various embodiments, the organic phase comprises an extracting agent, which may also be referred to as an extractant, to aid in transporting the impurities to the organic phase. For example, Di-(2-ethylhexyl)phosphoric acid (D2EHPA) may be used as an extracting agent. Cobalt is retained in the aqueous phase and Zn, Mn, and Ca are loaded in the organic phase.
The organic phase from solution extraction 108 may be then subjected to one or more wash stages and/or scrub stages in which the loaded organic phase is contacted with an aqueous phase in order to remove entrained/extracted aqueous cobalt bearing solution from the organic phase. However, in various embodiments, a wash stage is not included. The organic, phase may then be subject to a solvent stripping stage, wherein the impurities are transferred to an aqueous phase. For example, more acidic conditions may shift the equilibrium conditions to cause the impurities to migrate to the aqueous phase. The aqueous phase, which contains the impurities, may be processed in a suitable manner. The organic phase is thus purged of impurities and, in various embodiments, may be contacted again with liquids from liquid phase. Conditioned solution 118 thus comprises cobalt containing liquid from solution extraction 108.
In various embodiments, solution extraction 108 produces conditioned solution 118 and conditioned solution 117, Conditioned solution 118 may be forwarded to precipitation and filtration 112, to precipitate cobalt that was stripped from the organic phase in the wash/scrub stage.
Precipitation and filtration 112 may comprise a filtration process wherein a reagent is added to selectively precipitate cobalt. Precipitation and filtration 112 may comprise a precipitation that includes the use of a variety of precipitants, including, for example, calcium compounds such lime (calcium hydroxide and/or calcium oxide), calcium carbonate and milk of lime (certain preparations of calcium hydroxide). In various embodiments, any suitable source of lime may be used in precipitation and filtration 112. For example, lime may be added to precipitation and filtration 112 to precipitate cobalt as cobalt gypsum (“CoGyp”). Precipitation and filtration 112 thus produces precipitated cobalt 120. Precipitated cobalt 120 may be passed to leach 104.
Conditioned solution 117 may be passed to further processing 110. Further processing 110 may comprise any metal recovery process, such as ion exchange, electrowinning, solution extraction, carbon column filtering, and combinations thereof. Further processing yields cobalt metal 114.
Upstream bleed 122 comprises a portion of filtrate 107. Upstream bleed 122 may be used to bleed a portion of filtrate 107 to precipitation and filtration 112, thus bypassing solution extraction 108. As discussed above, upstream bleed 122 allows for the reduction of impurities from the circuit and for the reduction in process volumes in downstream processing. Upstream bleed 122 provides a portion of the liquid phase of filtrate 107 to precipitation and filtration 112, allowing the cobalt to be precipitated and the cobalt-depleted liquid phase with the impurities to be sent to elsewhere (e.g., to tails). Stated another way, upstream bleed 122 acts to reduce solution volumes, in turn reducing the volume of solution that is subject to other metal recovery processes. By reducing volume prior to other processing steps, the volume of solution used in the other processing steps relative to the cobalt contained therein is lower than in conventional systems. Accordingly, process equipment may be downsized as the equipment need not be sized to accommodate a large volume of low cobalt concentration liquor. The reduction in equipment size is also a cost savings over conventional systems on a per mass unit of cobalt recovered basis.
With reference to
Cobalt precipitation 204 may comprise any process by which cobalt is precipitated out of solution using reagent 202. Reagent 202 comprises a precipitating agent. In cobalt precipitation 204, any form of magnesium oxide may be used as a precipitating agent. For example, forms of magnesium oxide include solid magnesium oxide, calcined magnesium oxide and slurried, calcined magnesium oxide. Cobalt precipitation 204 may comprise multiple precipitation steps performed in parallel or in series. Cobalt precipitation 204 yields precipitated cobalt bearing material that is forwarded to leach 203.
Leach 203 is conducted in acid media under the addition of sulfur dioxide gas, though any suitable reducing agent may be used in lieu of or with sulfur dioxide gas. Sulfur dioxide addition acts to reduce cobalt III into cobalt II, which is readily dissolved into solution. Leach 203 may be performed under pressure and at temperatures above 25° C., though in various embodiments, leach 203 is conducted at atmospheric pressure and ambient temperature. In various embodiments, leach 203 is performed at atmospheric pressure and at a temperature of about 50° C. Leach 203 yields a leachate that is forwarded to leach residue filtration 106.
Leach residue filtration 106 comprises the thickening and filtering of solids from liquids of the leachate. Gypsum, which may be present in the leachate due to, for example, precipitation and filtration 112, is believed to act as a filtering aid in leach residue filtration 106. Leach residue filtration 106 produces solids 222. Solids 222 may be forwarded to, for example, a primary leaching process. In that regard, residual metals in solids 222, such as copper and cobalt, may be recovered. In various embodiments, solids 222 are sent to residue and/or neutralization 220. Neutralization 220 may comprise any suitable waste management or neutralization process. For example, lime may be added in neutralization 220 to regulate the pH of effluent prior to further processing.
The liquid portion of leach residue filtration 106 may be forwarded to Zn/Mn/Ca SX 207. Zn/Mn/Ca SX 207 comprises a solution extraction process that removes impurities such as one or more of, Zn, Mn, and Ca from the liquid portion of residue filtration 106. Cobalt is retained within the liquid portion. The aqueous phase, having its impurities partially or completely removed, may be referred to as extracted cobalt bearing solution 209. The aqueous liquid portion of leach residue filtration 106 may be contacted with an organic solution and an extractant.
Zn/Mn/Ca SX 207 uses D2EHPA as an extractant. After impurities are brought into the organic phase, the organic phase may be washed with water, though in various embodiments the organic phase is not washed. The organic phase may be scrubbed with dilute sulfuric acid to strip any cobalt that was extracted from the aqueous phase. After scrubbing, the dilute sulfuric acid, which now contains cobalt scrubbed from the organic phase, may be sent back to precipitation and filtration 112 via scrubbed cobalt solution 270. The organic phase may be stripped with an additional aqueous phase to bring impurities to the aqueous phase. The additional aqueous phase may be suitably treated, Acid for stripping the organic phase may be generated from other processes.
Extracted cobalt bearing solution 209 is then subjected to organic polishing 206. Organic polishing 206 comprises a filtration of extracted cobalt bearing solution 209 in a carbon column. A carbon column may comprise any suitable carbon media, such as, for example, activated charcoal, powdered activated carbon or granulated activated carbon, Carbon media may adsorb various impurities from extracted cobalt bearing solution 209. For example, carbon media may adsorb organic compounds from extracted cobalt bearing solution 209. Carbon media is suited for adsorption due to its high surface area, among other properties. In that regard, other media may be used in organic polishing 206 that are suitable for adsorbing or absorbing organic compounds. Carbon media may periodically be regenerated or replaced to maintain appropriate adsorbing performance. Organic polishing 206 produces polished cobalt bearing solution 211.
Polished cobalt bearing solution 209 may be forwarded to copper ion exchange (Cu IX) 208. Copper may be present at relatively low concentrations in polished cobalt bearing solution 211. Copper present in polished cobalt bearing solution 211 may exist as copper I and/or copper II. Cu IX 208 may be used to remove copper. Copper removed by Cu IX 208 may be in either metal or ionic form. Ion exchange may be accomplished in any suitable manner. For example, polished cobalt bearing solution 211 may be contacted with a surface or membrane containing ions. A surface or membrane in an ion exchange step may be comprised of a synthetic resin, a polymer, or any other suitable material. In various embodiments, for example, LEWATIT MONOPLUS TP207 resin, made by Lanxess of Birmingham, N.J. USA, is used. In further embodiments, PUROLITE S950 resin, made by Purolite, Inc, of 150 Monument Road, Bala Cynwyd, Pa. 19004, USA is used. Copper from cobalt bearing solution 211 may be exchanged with ions present on the surface or membrane, leaving copper present on the surface or membrane. The membrane or surface may be washed periodically to remove the adhered copper and increase efficacy of the ion exchange step. During such periodic washing, acid or other media may be contacted with the membrane or surface to remove the deposited copper ions. The acid or other media may be recycled into a primary leaching process to recover the copper ions washed off the membrane or surface. Cu IX 208 produces exchanged cobalt bearing solution 216. Copper removal could also be done with a suitable organic extractant using liquid liquid extraction, although in various embodiments, solvent extraction is not used for removing copper.
Exchanged cobalt hearing solution 216 is subjected to organic polishing 210. Organic polishing 210 may be conducted in the same or similar manner as organic polishing 206. For example, exchanged cobalt bearing solution 210 may be contacted with a carbon column to further remove impurities, such as organic compounds. Organic polishing 210 produces polished cobalt bearing solution 219.
Polished cobalt bearing solution 219 may be subjected to nickel ion exchange (Ni IX) 212, NiIX 212 may be accomplished in any suitable manner. For example, polished cobalt bearing solution 217 may be contacted with a surface or membrane containing ions. A surface or membrane in an ion exchange step may be comprised of a synthetic resin, a polymer, or any other suitable material. In various embodiments, for example, DOWEX M4195 resin is used. DOWEX M4195 is made by the Dow Chemical Company, Dow Water Solutions, Customer Information Center, P.O, Box 1206, Midland, Mich. 48642-1206. In further embodiments, for example, DOWEX XUS43605 resin is used. DOWEX XUS43605 is made by the Dow Chemical Company, Dow Water Solutions, Customer Information Center, P.O. Box 1206, Midland, Mich. 48642-4206. Nickel from polished cobalt bearing solution 219 may be exchanged with ions present on the surface or membrane, leaving nickel present on the surface or membrane. In various embodiments, a portion of the cobalt in polished cobalt bearing solution 219 may also become bound to the surface or membrane. NiIX 212 produces purified cobalt bearing solution 219.
The membrane or surface may be washed periodically to remove the adhered cobalt and increase efficacy of the ion exchange step. For example, Co Elution 216 comprises a regeneration or purging of the membrane or surface of NiIX 212 to remove cobalt that may have adhered to the membrane or surface. In that regard, Co Elution 212 may comprise contacting an elution medium, such as an acid medium, with the membrane or surface. The elution medium may be conducted to leach 203 to improve cobalt recovery.
The membrane or surface may be washed periodically to remove the adhered nickel and increase efficacy of the ion exchange step. Ni Elution 218 comprises a regeneration or purging of the membrane or surface of NiIX 212 to remove nickel that may have adhered to the membrane or surface. In that regard, Ni Elution 218 may comprise contacting an elution medium, such as an acid medium, with the membrane or surface. The elution medium may be conducted to tails.
Purified cobalt hearing solution 217 may be forwarded to electrowinning cell 214. Electrowinning cell 214 yields a cobalt metal cathode product 114. As those skilled in the art are aware, a variety of methods and apparatus are available for the electrowinning of cobalt and other metal values, any of which may be suitable for use in accordance with the present invention, provided the requisite process parameters for the chosen method or apparatus are satisfied.
In various embodiments, electrowinning may be performed in electrowinning cell 214 such that the anodes and cathodes are housed in separate compartments. For example, electrowinning cell 214 may comprise a cathode compartment and an anode compartment. Compartments may be formed by the placement of a hag or other barrier, whether permeable or semi-permeable, around or partially around one or more of the anodes and cathodes. For example, a bag may be placed around all or a portion of an anode. Cobalt metal may evolve at the cathode. Manganese, among others species, may evolve at the anode. Manganese and other species from the anode may be forwarded to a leach or other metal recovery processing operation. Lean electrolyte from the anode compartment may be forwarded to leach 203.
In various embodiments, electrowinning may be performed in electrowinning cell 214 such that the anodes and cathodes are not separated into compartments. In such embodiments, the anodes and cathodes are placed in the same media without a barrier and electrical current is applied. For example, electrowinning cell 214 may comprise a cathode compartment and an anode compartment. Metal values, such as cobalt, may evolve at the cathode. Manganese, among others species, may evolve at the anode.
With reference to
As discussed above, cobalt bearing material 102 may be produced in proximity to other metallurgical operations. For example, certain mining operations recover more than one metal from an ore body. Certain ore bodies comprise cobalt and copper, among other metals. Copper may be leached from an ore body in a primary leaching operation. During the processing of the leachate from such a primary leaching operation, it may be beneficial to begin cobalt recovery.
Cobalt precipitation 302 and cobalt precipitation 304 may comprise any process by which cobalt is precipitated out of solution using a precipitating agent. A precipitant or precipitating agent, used herein interchangeably, is an agent that, when added to a solution, causes at least a portion of a solute to precipitate. A variety of precipitating agents may be used to precipitate metal values. Any agent that may precipitate a metal value from an aqueous solution may be used as a precipitating agent. Precipitating agents may include various hydroxides and carbonates. More specifically, precipitating agents may include magnesium hydroxide, lime, magnesium oxide (also known in the art as magnesia), ammonium hydroxide, potassium hydroxide, calcium carbonate, ammonium sulphate, sodium carbonate, magnesium carbonate, potassium, and sodium hydroxide. In an exemplary embodiment, any form of magnesium oxide may be used as a precipitating agent. For example, forms of magnesium oxide include solid magnesium oxide, calcined magnesium oxide and slurried, calcined magnesium oxide. Each of cobalt precipitation 302 and cobalt precipitation 304 may comprise multiple precipitation steps performed in parallel or in series.
The use of one precipitant over another is determined based on a number of factors. As discussed above, cobalt produced using magnesium oxide is generally considered of greater quality than cobalt produced using lime. Generally speaking, industrially produced cobalt hydroxide using magnesium is approximately 30%-45% pure, whereas industrially produced cobalt hydroxide using lime is approximately 10%-25% pure. Cobalt hydroxide is a commercially marketable product, so the desired return on investment may be weighed using the present or predicted market price of both materials. Thus, it may be beneficial in operations that produce both products to adjust the balance of the type and amount of cobalt hydroxide that is recovered and the type and amount of cobalt hydroxide that is marketed directly.
A different precipitating agent may be used in each of cobalt precipitation 302 and cobalt precipitation 304. For example, magnesia may be added to cobalt precipitation 302 to precipitate cobalt as cobalt hydroxide. Lime may be added to cobalt precipitation 304 to precipitate cobalt as cobalt hydroxide. The precipitated cobalt hydroxide may be mixed to either in leach 104, immediately prior to leach 104, and/or combinations thereof.
With reference to
Primary leaching raffinate solution 408 is subject to cobalt precipitation 402. Cobalt precipitation 402 comprises the addition of magnesia to the primary leaching raffinate solution 408. The resultant slurry that forms in cobalt precipitation 402 is subject to solid liquid phase separation 410.
Solid liquid phase separation 410 may be accomplished in any suitable manner, including use of filtration systems, counter-current decantation (CCD) circuits, thickeners, and the like. In various embodiments, solid liquid phase separation 410 may comprise further conditioning processes such as, for example, filtration or clarification in clarifiers, to remove fine solid particles. A variety of factors, such as the process material balance, environmental regulations, residue composition, economic considerations, and the like, may affect the decision whether to employ a CCD circuit, one thickener or multiple thickeners, one filter or multiple filters, and/or any other suitable device or combination of devices in a solid liquid separation apparatus. However, it should be appreciated that any technique of conditioning the product slurry for later metal value recovery is within the scope of the present invention.
Solids from solid liquid phase separation 410 comprise a magnesium and cobalt hydroxide containing product, which may be referred to as Mg CHIP. As discussed above, Mg CHIP is regarded as a high quality cobalt bearing material.
Primary leaching raffinate solution 406 is subject to cobalt precipitation 404. Liquids from solid liquid phase separation 410 are also subject to cobalt precipitation 404. The addition of liquids from solid liquid phase separation 410 improves cobalt recovery, as unprecipitated cobalt may be retained in the liquids even after cobalt precipitation 402. Cobalt precipitation 406 comprises the addition of lime to the primary leaching raffinate solution 408 and liquids from solid liquid phase separation 410. The resultant slurry that forms in cobalt precipitation 404 is subject to solid liquid phase separation 412.
Solid liquid phase separation 412 may be accomplished in any suitable manner, such as those used in solid liquid phase separation 410, including use of filtration systems, counter-current decantation (CCD) circuits, thickeners, and the like. In various embodiments, solid liquid phase separation 412 may comprise further conditioning processes such as, for example, filtration, to remove fine solid particles. A variety of factors, such as the process material balance, environmental regulations, residue composition, economic considerations, and the like, may affect the decision whether to employ a CCD circuit, one thickener or multiple thickeners, one filter or multiple filters, and/or any other suitable device or combination of devices in a solid liquid separation apparatus. However, it should be appreciated that any technique of conditioning the product slurry for later metal value recovery is within the scope of the present invention.
Solids from solid liquid phase separation 412 comprise a lime precipitated cobalt hydroxide containing product, which may be referred to as lime CHIP. As discussed above, lime CHIP is regarded as of inferior quality to Mg CHIP. Lime CHIP is considered of lower quality because it contains gypsum due to the reaction of Ca ions in the precipitation.
The Mg CHIP and lime CHIP may be sold separately or mixed together in commercial markets. All or portions of the Mg CHIP and lime CHIP may be combined in leach 104.
With reference to
In various embodiments, electrowinning may be performed in electrowinning cell 502 such that the anodes and cathodes are housed in separate compartments. For example, electrowinning cell 502 may comprise a cathode compartment and an anode compartment.
Compartments may be formed by the placement of a bag or other barrier, whether permeable or semi-permeable, around or partially around one or more of the anodes and cathodes. For example, a bag may be placed around all or a portion of an anode. The electrolyte is thus divided into anolyte and catholyte. A bag that at least partially encloses the anode may be semi-permeable to anolyte. In that regard, analyte may be withdrawn from within the semi-permeable anode bag by the slight negative pressure created from an anolyte gas scrubber fan, thus avoiding the generation of acid mist within the electrowinning tankhouse. Bagged anodes may tend to prevent contact between the anode and cathode. Various anodes and anode coatings may be susceptible to short circuiting, thus it is beneficial to create barriers to prevent such short circuiting.
Cobalt metal may evolve at the cathode. Manganese, among others species, may evolve at the anode. Manganese and other species from the anode may be forwarded to a leach or other metal recovery processing operation. Lean electrolyte from the anode compartment may be forwarded to leach 203.
With reference to
With reference to
NiIX 212 produces polished cobalt bearing solution. Polished cobalt bearing solution may be split into two portions, portion 717 and portion 721. It should be noted that the relative size of portion 717 and portion 721 may vary over time. Portion 717 of polished cobalt bearing solution may be brought to electrowinning 502 which, as described above, comprises a bagged anode configuration. Electrowinning is conducted to yield cobalt metal 114 at the cathode.
Portion 721 of polished cobalt bearing solution may be subjected to manganese ion exchange (Mn IX) 706. Mn IX may be accomplished in any suitable manner. For example, portion 721 may be contacted with a surface or membrane containing ions. A surface or membrane in an ion exchange step may be comprised of a synthetic resin, a polymer, or any other suitable material. In various embodiments, for example, LEWATIT MONOPLUS TP207 resin, made by Lanxess of Birmingham, N.J. USA, is used. Manganese from portion 721 of polished cobalt bearing solution may be exchanged with ions present on the surface or membrane, leaving manganese present on the surface or membrane. The membrane or surface may be washed periodically to remove the adhered manganese and increase efficacy of the ion exchange step. During such periodic washing, acid or other media may be contacted with the membrane or surface to remove the deposited manganese ions. The acid or other media may be sent to neutralization 220 or other tails stream. Mn IX 706 produces exchanged cobalt bearing solution 723.
Exchanged cobalt bearing solution 723 may be subject to cobalt solution extraction 708. Solution extraction 708 may comprise any solution extraction process. In various embodiments, solution extraction 708 comprises a liquid-liquid extraction wherein cobalt is selectively loaded into an organic phase. During solution extraction 708, cobalt from exchanged cobalt bearing solution 723 may be loaded selectively into an organic phase in an extraction stage, wherein the organic phase comprises an extracting agent to aid in extracting cobalt to the organic phase and leaving impurities in the aqueous phase. For example, CYANEX 272 may be used as an extracting agent. The depleted cobalt bearing aqueous phase 716 may proceed to precipitation and filtration 112.
The organic phase from solution extraction 708 may be then subjected to one or more wash stages in which the loaded organic phase is contacted with an aqueous phase in order to remove entrained aqueous solution bearing droplets from the organic phase. The washed organic phase may then be subject to a solvent stripping stage, wherein the extracted cobalt is transferred to an aqueous phase. For example, more acidic conditions may shift the equilibrium conditions to cause the cobalt ions to migrate to the aqueous phase.
Conditioned solution 725 thus comprises cobalt containing liquid from solution extraction 708, which may also be referred to as a cobalt loaded aqueous stream.
Conditioned solution 725 is subject to cobalt salt precipitation 710. Cobalt salt precipitation 710 comprises any suitable process for precipitating ionic cobalt in a salt form. In that regard, precipitating agent 712 may comprise any suitable agent for precipitating cobalt. For example, sodium carbonate may be used in various embodiments. Cobalt salt 727 may be separated from liquids 714 by any suitable means. For example, liquids 714 may be decanted away from cobalt salt 727 or, also for example, liquids 714 may be separated by filtration, Liquids 714 may be recycled to other processes, such as leach 203.
Cobalt salt 727 may be forwarded to cobalt salt handling 718. Cobalt salt handling 718 may comprise the quantifying and/or qualifying of cobalt salt 727, Stated another way, cobalt salt 727 may be tested for quality and/or packaged for sale.
It is believed that the disclosure set forth above encompasses at least one distinct invention with independent utility. While the invention has been disclosed in the exemplary forms, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. Equivalent changes, modifications and variations of various embodiments, materials, compositions and methods may be made within the scope of the present invention, with substantially similar results. The subject matter of the inventions includes all novel and non-obvious combinations and sub combinations of the various elements, features, functions and/or properties disclosed herein.
Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any element or combination of elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of any or all the claims or the invention. Many changes and modifications within the scope of the instant invention may be made without departing from the spirit thereof, and the invention includes all such modifications. Corresponding structures, materials, acts, and equivalents of all elements in the claims below are intended to include any structure, material, or acts for performing the functions in combination with other claim elements as specifically claimed. The scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given above.
