MXPA00001588A - Chloride assisted hydrometallurgical extraction of copper from sulphide ore materials - Google Patents

Abstract

A process for the extraction of copper from a sulphide ore or concentrate comprises the steps of subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halide and sulphate ions to obtain a resulting pressure oxidation slurry. The slurry is subjected to a liquid/solid separation step to obtain a resulting pressure oxidation filtrate and a solid residue containing an insoluble basic metal sulphate salt. The basic metal sulphate salt is leached in a second leaching with an acidic sulphate solution to dissolve the basic metal salt to produce a leach liquor containing a metal sulphate, e.g. copper sulphate, in solution and a resulting solid residue. The leach liquor is separated from the solid residue and subjected to a solvent extraction process to produce metal concentrate solution and a metal depleted raffinate. At least a portion ofthe raffinate is recycled to the pressure oxidation.

Description

EXTRACTION H I DROMETALU RG ICA METAL ASSISTED BY CHLORIDE FIELD OF I NVENTION This invention relates to the hydrometallurgical treatment of concentrates or metal ores. In particular, it relates to the extraction of metals, such as copper, zinc, nickel and cobalt, from sulfide ores or other concentrates in the presence of halogen ions, such as chloride ions.

BACKGROUND OF THE I NVENTION It is known to treat hydrometrically concentrated sulphide concentrates, by which the concentrate is subjected to oxidation with pressure in the presence of chloride ions. See, for example, U.S. Patents 4, 039,406; 5,645,708; and 5,650,057. U.S. Patent 5,431,788 describes a chloride-assisted hydrologic hydrometal copper extraction process, which comprises subjecting a concentrate to oxidation with pressure to produce an insoluble copper salt and a liquor, which is recycled to oxidation with pressure, leaching the copper salt with acid sulfate solution to produce a leaching liquor containing copper sulphate in solution, subjecting the leach liquor to extraction with solvent, to produce a copper concentrate and a raffinate comprising ions of bisulfate or sulphate and protons in solution. The bisulfate ions or their phosphate and protons are then extracted from the raffinate by electrodialysis for I ss produce a solution of suff & ric acid, which is recycled to oxidation with pressure. This is continued because the acid produced during the extraction of copper solvent is very diluted, hence the electrodialysis process, by which the acid is extracted from the diluted solution, in order to produce a solution more concentrated acid. It is stated that this procedure is followed instead of simply evaporating the raffinate to remove water, because it is necessary to remove impurities in the raffinate, such as iron and zinc, and that the evaporation followed by recycling would return the impurities to the oxidation with pressure . However, it has now been found that a balance is established between the iron in solution and the hematite in the oxidation with pressure. Consequently, the return of iron to oxidation with pressure does not present a problem as expected. Due to the equilibrium that is established, the additional iron in solution is reported to the solid phase, so that the concentration of iron in solution does not increase. Because other impurities of less important metals, such as zinc, are soluble, they can be removed by taking a bleed stream from the liquor, which is recycled to oxidation with pressure.

BRIEF DESCRIPTION OF THE INVENTION According to the invention, a process is provided for the extraction of copper from a copper sulphide mineral or concentrate, comprising the steps of subjecting the ore or concentrate to oxidation with pressure in the presence of oxygen and an acid solution containing halide and sulfate ions, to obtain an oxidation paste with resultant pressure, subject the pulp to a liquid / solid separation step to obtain an oxidation filtrate with resulting pressure and a solid residue containing an insoluble basic copper sulfate salt; leaching the basic copper sulfate salt produced by oxidation with pressure with an acid sulfate solution to dissolve the basic copper salt to produce a leaching liquor containing copper sulfate in solution and a resulting solid residue; separating the leach liquor from the solid residue; subjecting the leach liquor to a solvent extraction process to produce a copper concentrate solution and a reduced copper raffinate; and recycling at least a portion of the raffinate to oxidation with pressure, characterized in that the raffinate is subjected to evaporation to remove water from it before recycling it. The term "concentrate" in this specification, refers to any material in which the metallic value content has been increased to a higher percentage by weight compared to the naturally occurring mineral, and includes artificial man-made sulfide mineral, such as, kills, and metal values precipitated as solids, such as hydroxides and sulfides. The additional objects and advantages of the invention will become apparent from the description of the preferred embodiments of the invention below.

, ¿Sa? T ~ BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow diagram of a metal hydrometallurgical extraction process according to an embodiment of the invention. Fig. 2 is a flow diagram of a metal hydrometallurgical extraction process according to another embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED MODALI DADES The mineral or concentrate fed to the process may contain one or more sulphide minerals of the base metals Cu, N i, Co and Zn, often combined with Fe and sometimes with other elements, such as , As, Sb and Ag. In Figure 1, the reference number 10 generally indicates a hydrometallurgical process according to one embodiment of the invention. The process 1 0 comprises a step of oxidation with pressure 1 2, an atmospheric leaching 14, an extraction of solvent 16, an evaporation step 20 and a neutralization 22. Before the oxidation stage with pressure 1 2, the copper concentrate it is first subjected to a regrind to reduce the particle size to approximately 2% + 325 mesh. The concentrate is subjected to oxidation with pressure 1 2 in an autoclave in the presence of an acid solution containing sulfate, chloride and, preferably, copper ions. The amount of acid introduced in the oxidation with pressure 12 is sufficient to maintain the discharge solution of the autoclave, when operated in a continuous mode, at a pH above 2.0, usually pH 2.3-3.8. The concentration of chloride ion in the solution in the autoclave is maintained at about 8-20 g / 1, preferably about 12 g / 1. The oxidation with pressure 1 2 is carried out at a temperature of about 1 1 5 ° C to about 1 75 ° C, preferably about 1 30 ° C to about 1 55 ° C, under a pressure of about 800-2,200 kPa. This is a total pressure that understands the oxygen pressure plus the vapor pressure. The retention time is approximately 0.5 - 2.5 hours and the process is normally carried out in a continuous way in the autoclave. However, the process can also be done in a batch form, if desired. In the oxidation stage with pressure 1 2, all the copper m ore are converted to their CuSO basic copper phosphate. 2 Cu (OH) 2, that is, all the copper that is recovered is reported to the solid phase in the oxidation with pressure 12. The solids content in the autoclave is maintained at approximately 12-25%, ie 1 50-300 g / l solids, as determined by the heat balance and viscosity constraints. The paste produced in the autoclave is discharged through a series of one or more instantaneous tanks (not shown) to reduce the pressure at atmospheric pressure and the temperature to approximately 90-1 00 ° C. The liquid part of the paste is referred to as the solution of -**- * - - - --- --me- - . - - ~ ^ .. product from the oxidation stage with pressure 1 2 and is indicated by the reference number 21. The paste or the instant tanks are filtered, as shown in 24, and the resulting filter cake is deeply washed to remove the trapped liquor as much as possible. The solids of the oxidation stage with pressure 1 2 after the filtration 24, are treated in the atmospheric leaching stage 14 at approximately pH 1.2 to pH 2.2, using refining of the extraction of solvent 1 6, which is acidic. , to dissolve the basic copper sulfate. The Leaching 14 takes place at a temperature of about 40 ° C for a retention time of about 1 5-60 m inutes. The percentage of solids in the feed for leaching 14 is normally about 3-1 5% or about 30-1 70 g / l, although it is possible to operate the process outside this range. The percentage of solids drops substantially during leaching 14 as basic copper sulfate dissolves. In this way, the product solids g / l can be as few as half the g / l feed solids. During the atmospheric leaching stage 14, the copper salts The basic ones dissolve almost completely, leaving very little of the iron present in the concentrate to the solution, provided that care is taken to maintain the pH in the range of 1.2 to 2.2, preferably pH 1.5 to 2.0. The paste 31 of the atmospheric leaching stage 14 is sometimes difficult, if not impossible to filter, but sits well. Given of the need to wash the leached solids very deeply, the ^^^^ j? * * * É ^ 'tt, l ^^^^ ll MM l ^ -.? J &"" wBMÉB & yesí &r, - á' # *. paste 31 is pumped to a counter-current decant washing circuit (CCD) 34. In the CCD circuit 34, the solids are fed through a series of thickeners with washing water added in the opposite direction. By this method, the solids are washed and the trapped solution is removed, along with the soluble metals dissolved in it. Approximately 3 to 7 thickeners (not shown) are required with a wash ratio (water to solids) of about 2 to 5 to reduce trapped liquor to less than 1 00 ppm Cu dissolved in the final residue. The lower flow of the thickener from the last thickener is the final residue stream 35 at about 50% solids. This can be treated for the recovery of precious metals, such as gold and silver, or it can be sent to waste. The main constituents of stream 35 are hematite and elemental sulfur, which can also be recovered by a combination of other processes, such as flotation and leaching in a sulfur-specific solvent, for example, perchlorethylene, if conditions warrant. of the market The top flow of the thickener from the first thickener is the product solution 33, which is fed to the solvent extraction stage 16, as shown. The copper is extracted from the product solution 33 in two stages (not shown) of extraction in the extraction stage with solvent 1 6 to produce a raffinate 37.

The raffinate 37 is divided, as indicated at 38, into three streams 40, 41 and 42. The stream 40, which comprises approximately 2/3 of the raffinate 37, is recycled to effect atmospheric leaching 14, as indicated above. The actual volume of 40 is determined by the acid needs of leaching 14, to dissolve the basic copper sulfate as described, and to maintain a slight excess of acid, ie, pH 1.5 - 2.0, which corresponds to about 1-5 g / l of H2SO. The acid requirements for stream 40 are less than the total acid contained in 37, and part of the remainder is used in oxidation with pressure 1 2 as a source of acid for reactions therein. This is supplied by stream 42. Any acid that is still subtracted from 37, not used by 40 or 42, is considered as excess and is neutralized. This is current 41. Normally, streams 41 and 42 are each about 1/6 of 37. Stream 41 is subjected to neutralization 22 with limestone and, after solid / solid separation 43, results in gypsum, which may be discharged, and wash water, which is recycled as wash water to the CCD washing circuit 34. The liquid 21 of the filtration 24, together with the stream 42, is subjected to evaporation 20 to remove water and produce an acid more concentrated and chloride solution 44, which is recycled to oxidation with pressure 1 2. The evaporation of the solution before recycling is problematic due to its highly corrosive nature, ie, high acidity (50 g / l of free acid ), high chloride content (1 2 g / l) and high evaporation temperature. This prevents the use of the majority, if not all, of the Jf > commercially available evaporators, which are usually based on indirect heat transfer through thin metal surfaces, such as tube and shell evaporators normally made of stainless steel. Titanium would be adequate, but it is too expensive if it is used in large quantities, which would be required for this type of application. However, the problem has been solved by direct combustion evaporation using submerged combustion of a fuel in solution 44 and using titanium material. In order to keep down the size of the evaporator, and minimize the operating and capital costs, the amount of water to be evaporated is minimized. In order to achieve this, the copper concentration in stream 31 is maintained at a more concentrated level, i.e. at about 30 to about 50 g / l, preferably about 35 g / l, compared to a value of 1. 2 g / l in the absence of evaporation. This generates, in turn, a more concentrated acid stream 42 containing approximately 48 g / l of H2SO4, instead of only 1 8 g / l of H2SO. This effectively reduces the volume of water to be evaporated by placing the same mass of acid in a smaller volume of water, thus reducing the size of the evaporator, thus justifying the use of titanium, and the fuel costs required to operate a direct combustion evaporator. The direct combustion evaporators do not have the advantage of the multiple effect of the generated steam, which can reduce, in a general way, the costs of ^^ fuel in the direct # evaporators, and thus justify evaporating a large volume of water. With reference to Figure 2, se. { our process 1 00 according to another embodiment of the invention. The process 1 00 also comprises a step of oxidation with pressure 12, atmospheric leaching 14, washing circuit CCD 34, extraction with solvent 1 6, evaporation 20 and neutralization 22. In the process 1 00, some of the metal values that are recovered are also reported to the oxidation liquid with pressure 21 in addition to the solid, said solid is subjected to atmospheric leaching 14, as described with reference to Figure 1. In Figure 2, the process steps that correspond to those in Figure 1 have the same reference numbers. The liquid 21 of the filtration 24 is subjected to a copper extraction with solvent 50, in order to recover copper values thereof. It should be noted that although step 24 is referred to as a filtration, any suitable liquid / solid separation method can be employed. Filtration 24 is the separation point between the high chloride liquid used in oxidation with 1 2 pressure, which It is recycled as indicated, and a low chloride or chloride-free liquid that goes to atmospheric leaching 14. Filtration 24 is always accompanied by a wash with water, or low water in recycled chloride, or a concentration of both for remove as much chloride from the solids (filter cake) as possible. The objective is to minimize the transfer of chloride from the circuit high in chloride to the low circuit in M - oruro, to counteract the formation of chloride in the last circuit. However, in spite of the washing of the solid residue produced by filtration 24, a small amount of about 0. 1% by weight of chloride is normally brought to atmospheric leaching 14. In this way, the concentration of chloride increases in the circuit low in chloride, because it is essentially a dead end circuit with minimal bleeding. This problem has been overcome by recycling a low-chloride circuit current to the high-chloride circuit. This current is indicated by the reference number 42 in Figure 2, to correspond to the stream 42 in Figure 1, which also comprises a recycle from the low chloride circuit to the high chloride circuit. Again, the stream 42 is subjected to evaporation 20, as described with reference to Figure 1, prior to recirculation to oxidation with pressure 12. However, in this case, there is no need to recycle acid from the low circuit in chloride because sufficient acid is generated by the extraction of copper with solvent 50 in the form of raffinate 63. In fact, it is usually necessary to neutralize some of the acid in the raffinate 63, as indicated in 64, before recycling the raffinate 63 As indicated at 65, the neutralization product is subjected to a liquid / solid separation step to produce solid gypsum, which can be discarded and a liquid 66, which is subjected to evaporation before recycling. .

Since there is no need to recycle acid from the low chloride circuit, the raffinate 37 from solvent extraction 1 6 is divided only into two streams, ie 2/3 in stream 40, which is used in atmospheric leaching 14, and 1/3 in stream 41, which is subjected to neutralization 22 and liquid / solid separation 43 to produce solid gypsum, which can be discarded and a stream 45, which is divided, as indicated in 46, to a stream that is recycled as wash water to the CCD circuit 34 and stream 42, which goes to evaporation 20 for recycling to oxidation with pressure 12 This serves to recycle chloride from the circuit low in chloride back to the circuit high in chloride. Although only the preferred embodiments of the invention have been described in detail herein, the invention is not limited thereto, and modifications may be made within the scope of the appended claims. , / aMfc ¿..? ¿¿¿¿¡¡¡¡¡¡¡¡¡^

Claims (10)

REVIVIENDS

1 . A process for extracting copper from a copper sulfide mineral or concentrate, comprising the steps of: subjecting the metal or concentrate to oxidation with pressure in the presence of oxygen and an acid solution containing sulfate and halide ions for obtaining a plating of oxidation with resulting pressure, subjecting the pulp to a liquid / solid separation step to obtain an oxidation filtrate with resulting pressure and a solid residue containing an insoluble basic copper sulfate salt; leaching the basic copper sulfate salt produced by oxidation with pressure with an acid sulfate solution to dissolve the basic copper salt, to produce a leaching liquor containing copper sulfate in solution and a resulting solid residue; separating the leach liquor from the solid residue; subjecting the leach liquor to a solvent extraction process to produce a copper concentrate solution and a reduced copper raffinate; and recycling at least a portion of the raffinate to oxidation with pressure, characterized in that the raffinate is subjected to evaporation in order to remove water therefrom before recycling it. 2. A process according to claim 1, wherein the evaporation is effected by means of a direct combustion evaporation process comprising the submerged combustion of a fuel in the raffinate to be recycled. 3. The process according to claim 1, further comprising the steps of dividing the raffinate into at least two portions, wherein one portion is recycled to oxidation under pressure and the other portion is recycled to the second leach. 4. The process according to claim 1, further comprising the step of recycling the oxidation filtrate with pressure to oxidation with pressure. 5. The process according to claim 4, further comprising the step of subjecting the oxidation filtrate with pressure to evaporation to remove water thereof, before recycling it to oxidation with pressure. 6. The process according to claim 5, wherein the evaporation is effected by means of a direct combustion evaporation process, comprising the submerged combustion of a fuel in the filtrate that is recycled. 7. A process according to claim 4, further comprising the steps of subjecting the oxidation filtrate with pressure to a solvent extraction process, before recycling the filtrate, to produce a concentrated copper solution and a reduced copper raffinate. additional, which is recycled from reduced copper raffinate additional to pressure oxidation. 8. The process according to claim 7, further comprising the step of subjecting the additional reduced copper raffinate to neutralization prior to recycling thereof to oxidation with pressure. ggH ^^ 9. The process according to claim 1, wherein the oxidation with pressure is carried out at a pH value above about 2. 10. The process according to claim 9, wherein the pH in oxidation with pressure is from about 2.3 to about 3.8. eleven . The process according to claim 1, wherein the second leaching is carried out at a pH in the range of about 1.2 to about 2.2. 2. The process according to claim 11, wherein the pH in the second leaching is from about 1.5 to about

2. 0. The process according to claim 1, wherein the oxidation paste with pressure is flared at atmospheric pressure at a temperature below the melting point of the sulfur as an element. 14. The process according to claim 1, wherein the halide is selected from chloride and bromide. 5. The process according to claim 1, wherein the concentration of copper in the leach liquor is maintained at a value from about 30 g / l to about 50 g / l. 16. The process according to claim 1, wherein the concentration of copper in the leach liquor is maintained at a value of about 35 g / l. * & fa * £ sa & amp; & amp; amp; A process for the extraction of copper from a sulfide ore or concentrate comprises the steps of subjecting the concentrate or concentrate to oxidation with pressure in the presence of oxygen and an acid solution containing sulphate and halide, for obtain an oxidation paste with resulting pressure. The paste is subjected to a liquid / solid separation step to obtain an oxidation filtrate with resulting pressure and a solid residue containing a sulphate salt of 10 basic metal nsoluble. The basic metal sulfate salt is leached in a second leach with an acid sulfate solution to dissolve the base metal salt to produce a leaching liquor containing a metal sulfate, for example, copper sulfate, in solution and a residue resulting solid. The leach liquor is separated from the solid waste and 15 subjected to a solvent extraction process to produce a concentrated metal solder and a reduced metal raffinate. At least a portion of the raffinate is recycled to pressure oxidation.