MXPA99011441A

MXPA99011441A - Method for separating and isolating precious metals from non precious metals dissolved in solutions

Info

Publication number: MXPA99011441A
Application number: MXPA/A/1999/011441A
Authority: MX
Inventors: H Green Dennis; J Mueller Jeffrey; A Lombardi John
Original assignee: H Green Dennis; Hw Process Technologies Inc; A Lombardi John; J Mueller Jeffrey
Priority date: 1997-06-09
Filing date: 1999-12-09
Publication date: 2001-05-17

Abstract

Se proporciona un método para separar oro y/o plata de cobre u otros metales contaminantes, en donde se utiliza una membrana de filtro adecuada (64), particularmente un nanofiltro, para formar un retentato (134) que contiene la mayor parte de los complejos multivalentes de metal-cianuro, y un permeado (135) que contiene la mayor parte de los complejos de metal precioso-cianuro. El proceso es particularmente aplicable a la recuperación de oro y/o plata a partir de minerales que contienen estos metales y uno o más metales contaminantes. El metal precioso posteriormente se puede recuperar a partir del permeado (135), y el metaldel complejo de metal-cianuro multivalente a partir del retentato (134).

Description

METHOD FOR SEPARATING AND ISOLATING PRECIOUS METALS FROM NON-PRECIOUS METALS DISSOLVED IN SOLUTIONS FIELD OF THE INVENTION The present invention relates in general to the processing of solutions containing precious metals, contaminated with metal, and more particularly to a method where gold ore which also contains copper and other polluting metals is treated, to effectively separate gold = from copper and other polluting metals.

BACKGROUND To recover the elemental gold (Au) of the mineral containing gold, the mineral is usually brought into contact with one or more leaching solutions containing aqueous cyanide. (or leaching). Gold and other metals dissolve in the solution, forming different complexes of metal cyanide, such as Au (CN) 2-1 and Cu (CN) 3 ~ 2. A variety of different physical methods can be used to bring the mineral into contact with the leaching solution containing cyanide. Two common methods are heap leaching and heap leaching. In heap leaching, the coarsely crushed ore is placed in a pile, which is placed on a waterproof liner. The cyanide-containing leaching solution is applied to the top of the ore pile, and allowed to travel (eg, percolate) through the pile. An impregnated leaching solution containing one or more monovalent gold-cyanide complexes, and other dissolved metal cyanide complexes, is collected on the liner at the bottom of the stack. In tank leaching, the finely ground ore is placed in a large container or "tank," together with the cyanide leaching solution, to form a paste. The solution extracts gold and other metals from the mineral that forms the impregnated leaching solution. A number of different procedures can be employed to recover the dissolved gold from the cyanide solution. Two common gold recovery methods are the Merrill-Crowe process, and the activated carbon process. In the Merrill -Crowe process, the impregnated leaching solution undergoes zinc foundation / precipitation reaction. Specifically, the impregnated leaching solution containing gold-cyanide complex, is combined with elemental zinc (Zn), to generate solid elemental gold (Au), which resides inside a reaction product of solid gold-zinc sludge. The product is removed by filtration-from the residual liquid fraction (consisting primarily of free cyanide ions [(CN) ~], and a complex of Zn (CN) 4 ~ (ac) dissolved). The product is processed to isolate and recover the elemental gold, by combining the product, after washing with water, with sulfuric acid (H2S04) in the presence of air, to dissolve the excess elemental zinc (unreacted), and other metals, including copper and cadmium.

The remaining solid material is melted in the presence of a flow to produce a highly pure gold doré. In the activated carbon process, the impregnated leaching solution is contacted with activated carbon, and the gold-cyanide complexes dissolved in solution are adsorbed onto the surface of the activated carbon. After adsorption, the gold containing carbon product is filtered to remove the residual "waste" liquid, followed by "desorption" or removal of the gold-cyanide complex from the "charged" activated carbon (for example, the carbon product). containing gold), passing an eluent solution through the carbon. It is theorized that the cyanide ions [(CN) ~] in the eluent solution, effectively replace / exchange the adsorbed aurocyanide ions (gold-cyanide complex), which are released into the eluent solution. The eluent product containing the resulting gold (which contains the desired gold species [aurocyanide ions / gold-cyanide complex]) is then processed by any suitable technique to recover the elemental gold. Regardless of the methods that are finally used to obtain elemental gold from gold-cyanide complexes, numerous technical and economic problems can occur when processing gold ore that contains substantial amounts of elemental copper and other polluting metals. These metals may have a stronger affinity for cyanide ions than gold, and form metal cyanide complexes. For example, the copper-cyanide complex (Cu (CN) 3), which is generated as a result of this reaction, is unable to extract tel gold from the gold ore to produce the desired gold-cyanide complex, and consumes 3 moles of (CN) ~. As more copper is leached into the recirculating leaching solution (which occurs during the reuse of this material and its repeated passage through the input amounts of gold ore), increasingly large amounts of cyanide are lost to this complex. These polluting metals, therefore, can cause excessive cyanide consumption, thus increasing the operating and capital expenses of the process, and substantial reductions in the operational efficiency of the entire gold production facility. In addition to the excessive consumption of cyanide, copper and other metals inside the gold ore, they can also result in an increasingly impure elemental gold product. Therefore, additional and more expensive refining procedures must be employed to solve this problem. As an example, if the Merrill-Crowe process is used, the extraneous copper materials in the solution can dramatically reduce the efficiency of the system's precipitation, causing zinc passivation, with the term "passivation" implying a process in which the zinc becomes non-reactive with the gold-cyanide complex, which prevents the gold precipitation process from taking place. Additional zinc is often required, which again increases overall production costs. Excessive contamination with polluting metal from the leaching solution can also reduce the operating efficiency of the casting process associated with this mode, resulting in prolonged casting times. For example, in systems that employ the activated carbon process, copper materials (eg, copper-cyanide complexes) will substantially inhibit the functional capabilities of activated carbon, thereby "contaminating" this material, and cause greater consumption of coal. In the same way, the energy consumption in the subsequent electrolytic extraction stages is increased if many contaminating metals are not removed from the system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for separating gold and / or silver from copper and other polluting metals in a gold and / or silver processing system, which makes possible the removal of copper and / or other metals. polluting metals of the system.

In another object of the invention provide a method for separating gold and / or silver from copper and other polluting metals in a gold and / or silver processing system, which makes it possible for the purity levels of elemental gold and / or silver to be relatively high It is a further object of the invention to provide a method for separating gold and / or silver from copper and other polluting metals in a gold and / or silver processing system, where the removal of copper and other polluting metals is carried out with a consumption relatively low cyanide and other reagents, in such a way as to improve the overall efficiency of the system. The claimed process overcomes the problems described above in a very effective way, which will become clearer from the detailed information presented below. Although specific processing systems and gold and / or silver recovery technologies will be discussed in connection with the claimed process, the present invention will not be limited to any method of extracting gold and / or silver based on particular cyanide, or to solutions leaching in general. Instead, the invention is prospectively applicable to any production system that places materials containing gold and / or silver in physical contact with solutions containing free cyanide ions [(CN) ~], so as to generate a gold-cyanide and / or silver complex as defined above, as well as any other application where solutions containing gold and / or silver contaminated by other metals are treated to recover gold and / or silver. For example, the processes of the present invention are applicable to electroplating solutions. In one embodiment of the present invention, a process for recovering a dissolved monovalent precious metal cyanide complex (e.g., Au (CN) 2) from a cyanide solution containing the monovalent precious metal cyanide complex is provided. dissolved, and one or more dissolved multivalent metal cyanide complexes (e.g., Cu (CN) 3). A complex of monovalent precious metal cyanide is a complex consisting of gold or silver with two or more cyanide ions, and therefore, has a total charge that has an absolute value of 1. A multivalent metal cyanide complex is a complex formed by a different metal of gold or silver, with three or more cyanide ions, and has a total charge that has an absolute value of two or more. The process includes the steps of: (a) passing the cyanide solution through a filter to form a retentate containing a portion of the dissolved monovalent precious metal cyanide complex and most of one or more metal cyanide complexes dissolved multivalents, and a permeate containing most of the dissolved monovalent precious metal cyanide complex; and (b) subsequently recovering the precious metal from the permeate to form a precious metal product. The retentate does not pass through the nanofiltration membrane, while the permeate passes through the membrane. The permeate typically contains more than about 50 percent of the dissolved monovalent precious metal cyanide complex, but less than about 50 percent of the dissolved multivalent metal cyanide complex. In contrast, the retentate typically contains more than about 50 percent of the dissolved multivalent metal cyanide complex, but less than about 50 percent of the monovalent precious metal cyanide complex. Accordingly, the claimed method effectively removes unwanted multivalent metal cyanide complexes (e.g., metal cyanide complexes where the metal is copper, zinc, cobalt, iron, calcium, magnesium, nickel, lead, cadmium, mercury, platinum, and palladium) in the early stages of production in a fast and efficient manner. The cyanide solution can be formed by any number of processes. Commonly, the solution is formed by contacting a precious metal containing material with an aqueous cyanide solution (eg, a leach) to extract the metal content of the material in the solution. The cyanide-containing solution will be defined to encompass a solution, preferably aqueous, comprising free cyanide ions [(CN) ~] therein, in combination with a selected counter-ion (e.g., Na +, K +, Ca + 2, and similar). Representative cyanide solutions suitable for this purpose will generally contain a dissolved cyanide compound (salt) therein, including representative examples of this material, but not limited to, sodium cyanide (NaCN), potassium cyanide (KCN), calcium cyanide (Ca (CN) 2), ammonium cyanide (NH 4 CN), organic alpha-hydroxyl cyanides (eg, lactonitrile), and mixtures thereof. The liquid product will typically include about 1x10 -1x10 weight percent gold-cyanide complex, and about 0.05-1.0 weight percent multivalent metal cyanide complexes, although these values are subject to change according to type, degree, and particular nature of the material being processed. The filter can be any suitable filtration device that is capable of selectively removing the desired multivalent metal cyanide complexes from the solution. Preferably, the filter has a pore size of about 5 to about 100 angstroms, and more preferably about 10 to 20 angstroms. Preferred filters include electrically charged filters that generally repel dissolved multivalent metal cyanide complexes while passing dissolved monovalent precious metal cyanide complexes, with a "nanofiltration type membrane" being preferred. As will be appreciated, the conditions under which the separation is effected are important for separation efficiency. In a preferred embodiment, the solution is supplied to the filter at a preferred and optimum flow rate of approximately 378-37,854 LPM (liters per minute), although this value may vary as necessary according to preliminary pilot studies involving the system particular in consideration and its global capacity. The passage of the permeate through the filtration membrane normally occurs at an optimum and non-limiting membrane flow rate of approximately 81.5-815 LMD (liters per square meter per day). The precious metal can be recovered from the permeate by any number of techniques. The term "recovery" and "recover" in connection with the recovery of gold and / or elemental silver, and / or other metals, may comprise a number of processes, and shall not be restricted to any precious or non-precious metal isolation techniques. particular. For example, the recovery method can be by foundations (eg, the Merril-Crowe process), amalgamation (eg, using an amalgamating agent, such as mercury), precipitation (eg, as a sulfide), electrolysis ( for example, electrolytic extraction), ion exchange (e.g., solvent extraction), and / or adsorption or absorption (e.g., the activated carbon process), or any combination thereof. After recovery of the precious metal, the permeate can be recycled to extract additional precious and not precious metals from the additional material. For example, the permeate can be passed through a second filter having a pore size smaller than the first filter, to form a second retentate, which includes at least most of the dissolved monovalent metal cyanide complexes remaining in the permeate after the recovery step, and a second permeate that includes at least the majority of the water in the permeate. The retentate can be subjected to additional recovery steps to recover one or more of the metals in the dissolved multivalent metal cyanide complexes and / or in the cyanide complexes. By way of example, the retentate can be contacted with a chelating agent, and subsequently the cyanide is removed from the retentate to form a retentate emptied of cyanide; the metal recovers from the retentate emptied of cyanide to form a wasteful retentate; and the wasteful retentate is passed through a filter to form a second retentate that includes at least most of the chelating agent in the waste stream, and a second permeate. The retentate can be acidified to convert the cyanide to HCN; the HCN is removed from the acidified retentate as a gas to form a cyanide drained retentate; the drained retentate is contacted with a base to form an electrolytic solution for an electrolytic extraction cell; and the metal is recovered in the electrolytic extraction cell. The retentate casting metal can be passed through a second filter to form a second retentate to be recycled to the electrolytic extraction step, and a second permeate. The retentate can be contacted with an acid to precipitate the retentate metal as a metal cyanide compound. The metal cyanide compound is dissolved in an aqueous solution to form an electrolyte solution; and the electrolyte solution is subjected to electrolytic extraction to recover the metal. Finally, the metal can be adsorbed from the retentate on a substrate (e.g., activated carbon), the metal is desorbed in an eluate solution; the eluate is passed through a second filter to form a second retentate that includes at least most of the copper and a second permeate; and the second retentate is subjected to electrolytic extraction. Alternatively, instead of processing the metal cyanide complex as described above, this material (eg, the retentate) can be disposed of in an appropriate manner. In a further embodiment of the present invention, there is provided a process for recovering the dissolved precious metal cyanide complex, where the precious metal is first recovered from the solution to form a precious metal cast solution, and the cast metal solution The precious metal is then passed through a filter to form a retentate containing at least most of the complex of dissolved multivalent metal cyanide and a permeate, which contains in general the majority of any remaining precious metal cyanide complex in the solution emptied of precious metal. The recovery step may include adsorbing the precious metal and the metal of the multivalent metal cyanide complex of the solution on a substrate; Desorb the precious metal and metal to form an eluate solution that includes dissolved precious metal and dissolved metal; and electrolytically extracting the precious metal from the eluate solution. The separation method described above can offer a number of benefits. You can more effectively use cyanide-containing species (eg, free cyanide ions [(CN) ~]), by removing multivalent metal cyanide complexes from the system, and thereby reduce production costs in relation to existing processes. The elimination of the multivalent metal-containing species (for example, the copper-cyanide complex) of the system can also prevent the interference of these metals with the subsequent processing steps, including the steps of electrolytic extraction and smelting. As a result, the "impure" precious metal ore (previously considered economically undesirable) can be processed in an effective manner for the cost. The easily applicable to a wide variety of cyanide-based treatment methods. It is highly versatile and satisfies a long-felt need in the gold processing industry. It can decrease, in relation to existing processes, the consumption of different cyanide reagents, including activated carbon and zinc (depending on the particular recovery system under consideration). It can reduce the electricity consumption in the electrolytic extraction in relation to other processes. It can conserve resources and reduce the generation of waste, which collectively provides important benefits for the environment. It can reduce, in relation to other processes, the casting time that is needed to produce an elemental gold product. You can recover non-precious metals from the precious metal ore, which can be sold at a considerable economic benefit. Finally, it can produce a highly pure precious metal product dore. BRIEF DESCRIPTION OF THE DRAWINGS - Figure 1 is a schematic flow chart illustrating a first embodiment of the present invention. Figure 2 is a schematic view partially broken away in parts of a representative nanofiltration membrane cartridge unit, which is suitable for use in the different embodiments of the invention. Figure 3 is a schematic flow diagram illustrating a second embodiment of the present invention. Figure 4 is a schematic flow diagram illustrating a third embodiment of the present invention. Figure 5 is a schematic flow diagram illustrating a fourth embodiment of the present invention. Figure 6 is a schematic flow chart illustrating a fifth embodiment of the present invention. Figure 7 is a schematic flow chart illustrating a sixth embodiment of the present invention. Figure 8 is a schematic flow diagram illustrating a seventh embodiment of the present invention. Figure 9 is a schematic flow diagram illustrating an eighth embodiment of the present invention. - Figure 10 is a schematic flow diagram illustrating a ninth embodiment of the present invention. Figure 11 is a schematic flow diagram illustrating a tenth embodiment of the present invention. Figure 12 is a schematic flow diagram illustrating a eleventh embodiment of the present invention.

DETAILED DESCRIPTION Referring to Figure 1, a first embodiment of a ore processing system 10 is illustrated. In the system, a supply of ore containing precious metal 12 is initially provided. The present invention will not be limited to any parameters , materials, components, mineral grades, and particular equipment used in connection with the leaching process and the system 10. Any leaching process based on cyanide can be used, provided that an aqueous liquid product containing a cyanide is produced. precious metal cyanide complex in it. However, this invention relates primarily to the use of precious metal ore 12 that not only contains elemental precious metals (eg, gold (Au and / or silver (Ag)), but also includes substantial amounts of elemental non-precious metals. , for example copper (Cu) In a representative and non-limiting embodiment, the most precious metal ore 12 of interest in the claimed invention will contain from about 0.0001 to 0.0005 weight percent elemental gold, and / or about 0.005 to about 0.025 weight percent elemental silver, and about 0.1 to 2 weight percent non-precious elemental metal, although the precious metal may be gold or silver (gold being the most preferred), and Non-precious metal can be any metal that forms a multivalent cyanide complex in solution (copper being the most preferred), for simplicity, the process will only be described with reference specific to copper / gold ore. As shown in the embodiment of Figure 1, the ore 12 is provided in the form of rock materials 14 which are configured in a pile or pile 16. The term "rock materials", as used herein, includes, without limitation, separate portions or "pieces" of rock having an average diameter of approximately 2.54 to 10.16 centimeters, crushed rock / powder (for example, with an average particle size (non-limiting) of standard mesh of the United States approximately 200 or less), or large sections / ore deposits, all of which are normally treated at a mine site. This invention, and the cyanide treatment processes of interest, will not be restricted to any particular physical characteristics in relation to the gold ore 12, the discussion of the rock materials 14 (and the dimensional parameters mentioned above) being provided for purposes of example. Reducing the size of the ore 12 to a desired level (for example, to create the rock materials 14 having the desired size characteristics, as described above), can be undertaken in a conventional manner, using standard equipment, including units jaw crushers, crushing mills, and / or roller crusher systems, which are known in the art for this purpose. The pile 16 of gold ore 12 is usually of a significant size. For example, representative ore piles 16 can usually be approximately 9 to 15 meters high, and will occupy approximately 0.0283 x 10 to 0.0849 x 10 cubic meters of space, although these values may vary as necessary according to the site. of mine / processing facility under consideration. In a preferred embodiment, each pile 16 of ore 12 (e.g., rock materials 14) is placed on a cushion 20 made of rubber or other composition that is substantially inert relative to the cyanide salt materials normally found in the leaching process. Subsequently, a leaching solution containing cyanide therein (for example, a "leaching solution containing cyanide" 22), which is initially held in a containment vessel 24 made of stainless steel or other inert material, is applied to the ore stack 16 by means of tubular conduit 26. Tubular conduit 26 is operably connected to a sprinkler assembly 30. Sprinkler assembly 30 can be of any conventional design, optimally having multiple nozzles 32 associated therewith (Figure 1) . Although the cyanide concentration of the solution-leach 22 may vary according to a wide variety of parameters, including the type and character of the gold ore 12 being treated, a representative and preferred leaching solution 22 will contain from about 0.1 to 2 percent by weight of compound containing dissolved cyanide. It should also be noted that the conduit 26 (as well as any of the other conduits of the system 10, as described below), may include one or more pumps in-line therein (not shown) if necessary according to the studies. preliminary pilot on the specific processing system under consideration. The particular pump that can be employed for this purpose can be of any conventional type suitable for transporting the materials under consideration, including, but not limited to, centrifugal, positive displacement pumps, and / or other pumps known in the art. In most cases, it is desirable and important, from a safety and efficiency point of view, to ensure that the pH of the leaching solution 22 is maintained at a level of about 9 to 11. At pH levels below 9, harmful gases are generated that endanger personnel. At pH levels greater than 11, the recovery of the desired gold-cyanide complex (discussed below) can be impeded. To reach this goal, as determined by preliminary and routine pilot studies, it may be necessary to periodically test and adjust the pH of the leaching solution 22 before, and / or during, the use, by the addition of a selected alkaline composition to solution 22. Preferred compounds suitable for this purpose include calcium oxide (which is also known as "lime" or CaO), as well as NaCO, and / or NaOH. The alkaline composition is shown schematically in Figure 1 in reference number 34, and is introduced into the system 10 by means of tubular conduit 36. The amount of alkaline material to be used (if necessary) will vary depending on the pH relative to the leaching solution 22, the chemical content of the ore 12 being processed, and other parameters, including the specific type of processing system under consideration. The amount of alkaline material (and the overall need for this additive), therefore, can be determined in accordance with routine testing procedures involving conventional pH analysis equipment, which provides continuous monitoring of the leaching solution 22 before and during its use. In a representative and non-limiting embodiment, normally from 0.1 to 1 gram of calcium oxide (CaO) per liter of the leaching solution 22, which is formulated as discussed above, will be used. However, it is important to emphasize that the use of alkaline materials (as well as any other additives) in the leaching solution 22 is optional, the need for these materials being again determined in accordance with the preliminary studies on the gold ore 12 I'm trying, and other factors. There is the same situation in relation to the total amount of leaching solution 22 to be used in relation to the pile or pile 16 of ore 12. However, in a representative and non-limiting mode (which is subject to variation if necessary , as a preliminary analysis is determined), normally approximately 757 to 1,893 liters of leaching solution 22 having the characteristics mentioned above will be used, per ton of ore 12 (in the form of rock or dust). The leaching solution 22 is introduced into the pile 16 of rock materials 14 (e.g., gold ore 12) at the top 40 thereof, such that the leaching solution 22 is placed in direct physical contact with the ore. 12. Subsequently, the leaching solution 22 is allowed to pass down (for example, percole) through the stack 16, extracting the gold from the rock materials 14 (ore 12), as it passes over and through the_ mineral 12. This process is facilitated by the very porous nature of the rock / ore 14 materials, as discussed above. The resulting liquid product (shown in Figure 1 in reference number 42) is collected as it leaves the stack 16 at the bottom of the stack. At this point, the liquid product 42 will contain unreacted cyanide materials therein (eg, cyanide ions [(CN) ~]), together with (1) a gold-cyanide complex; and (2) a copper-cyanide complex. The term "gold-cyanide complex" will be generally defined to encompass a monovalent chemical complex containing one or more gold ions therein, stoichiometrically combined with one or more cyanide ions [(CN) ~]. This complex will normally consist of Au (CN) 2 (also known as an "aurocyanide ion"), which is associated with one or more counterions, including, for example, Na + when NACN is used in the production of the leaching solution. 22, K + when KCN is used, and Ca when Ca (CN) 2 is involved. The complex of Au (CN) _2 has a high level of stability, with a KF of approximately 2 x 10 -. A typical reaction sequence in which a gold-cyanide complex of the type described above is produced, using a leach solution containing selected cyanide 22, is as follows: 4Au (s) + 8 (CN) - (ac) + 02 (ac) + 2H20 - 4Au (CN) "2 (ac) + 40H" (ac) The term "copper-cyanide complex", as used herein, will be defined to involve a multivalent chemical complex containing one or more copper ions stoichiometrically combined with one or more cyanide ions [(CN) -]. This complex will normally consist of Cu (CN) 3 - (also known as a "cuprocyanide ion"), which is associated with one or more counter-ions, including, for example, Na + when NaCN is used in the production of the solution leaching 22, K + when KCN is used, and Ca + 2 when Ca (CN) 2 is involved. The typical reaction that forms the copper-cyanide complex, is as follows: 2Cu (s) + 6 (CN) "(ac) - > 2Cu (CN) 3- (ac) Much "He1 copper-cyanide complex (Cu (CN) 3), which is generated as a result of this reaction, passes unaffected through the gold extraction and isolation processes described above, and ultimately resides in the materials of the solution containing cyanide "yerma", which remain after the gold-cyanide complex is removed. " This waste solution is normally reused / recycled in the treatment of the additional gold ore input quantities 12. With respect to the amount of copper-cyanide ((Cu (CN) 3) in the liquid product 42 at this point, normally it will contain from about 1 x 10 to 1 x 10 weight percent gold-cyanide complex, and from about 0.05 to 1.0 weight percent copper-cyanide complex, although the claimed process will not be restricted to a liquid product 42 having these parameters, which will vary according to the type of gold ore 12 being processed, and other extrinsic factors.The liquid product 42 can subsequently pass through the tubular conduit 46 to an optional solids filter. , which is used to remove the foreign particulate matter (e.g., residual ore or "gangue" materials) from the liquid product 42. In a preferred embodiment, the solids filter 50 will consist of a filter d e recessed washable sand bed known in the art or in another suitable system. The solid materials trapped by the solids filter 50 (schematically designated in reference number 52 in Figure 1) are finally directed out of the filter 50 and system 10 to be discarded through the tubular conduit 54. The use of a Solids filter 50 for this purpose is again optional, as determined by the preliminary pilot studies on the particular liquid product 42 under consideration, and its total solids content. After passage of the liquid product 42 through the solids filter 50 (if used), the liquid product 42 is ready for further processing. As noted, the liquid product 42 in the same manner may contain other materials therein (e.g., species containing dissolved metal derived from a number of different metals, including silver (Ag), lead (Pb), and Similar) . The type and amount of these additional materials in the liquid product 42 will depend on the particular mineral 12 being treated. The liquid product 42 can be temporarily stored in one or more large outdoor pond type structures (not shown), or it can be immediately subjected to further processing, depending on the overall capacity of the system 10, as determined by a preliminary test . Continuing with the reference to Figure 1, the liquid product 42 is directed directly from the stack 16, the solids filter 50 (if used), or a temporary containment pond (if used), towards the separation system 56 of the present invention, by the tubular conduits 60, 62. The separation system 56 generally consists of at least one, and preferably multiple, nanofiltration membrane units. In Figure 1, a single representative nanofiltration membrane unit 64 is illustrated in schematic format. Other information regarding nanofiltration, also is presented in the Patents of the United States of North America Numbers 5,476,591 and 5,310,486, which are each incorporated herein by reference. It should be noted at this point that the present invention will not be restricted to any specific configuration or number of nanofiltration membrane units or nanofiltration membranes themselves (but may include other types of filters). If multiple membrane units are used, they can be configured in series, in parallel, or in a combination of both, as discussed in more detail below (along with the specific examples). The final configuration of the nanofiltration membrane units in the separation system 56 will depend on a variety of factors, including the chemical character and content of the liquid product 42, the size / total capacity of the system 10, the flow rate of the liquid product inlet 42, the size of the nanofiltration membrane units under consideration, and other factors, as determined by a preliminary test. For example, in applications involving a liquid product 42 having a relatively high inlet flow rate (eg, exceeding about 3,785 LPM or more), the liquid product 42 is preferably divided into a plurality of portions, which are passed through a series of nanofiltration membrane units operated in parallel, followed by the passage of the liquid product 42 through a series of nanofiltration membrane units operated in series. This technique makes it possible to handle and treat relatively large initial feed currents in a faster and more efficient manner, without overloading the system 10. In addition, the final number of nanofiltration membrane units in the separation system 56 of the the same way will vary (from one to multiple units), again depending on the amount of liquid product 42 to be treated, the concentration-of the copper-cyanide complex and the gold-cyanide complex in the liquid product 42, the initial flow velocity, and other factors. As noted above, specific examples of multiple nanofiltration membrane systems that are suitable for use herein will be provided below. In the same way, the claimed invention will not be limited to any input flow velocity in relation to the liquid product 42 as it enters the separation system 56. Regardless of whether a single or multiple unit system is employed. of nanofiltration, it is preferred that the liquid product 42 is supplied to the selected separation system 56 (e.g., nanofiltration membrane units), at a representative, non-limiting flow rate of about 378 to 37,854 LPM (liters per minute) , varying this parameter as necessary according to the routine preliminary testing procedures. However, before filtering the liquid product 42 using the nanofiltration membrane separation system 56 as discussed in a substantial detail below, another important factor deserves further consideration. Specifically, at least one antifouling composition can optionally be added to the liquid product 42 prior to nanofiltration in the separation system 56. The use of an antifouling composition is preferred when the liquid product 42 contains substantial amounts of dissolved calcium or other salts sparingly soluble therein. For example, the addition of a composition against scale is desirable when the liquid product 42 contains more than about 0.1 grams / liter of calcium ions therein. The dissolved calcium within the liquid product 42 may leave the ore 12 being treated, and / or may result from the use of "hard" water when initially preparing the aqueous leaching solution. With reference to Figure 1, a supply of a selected fouling composition (discussed further below) is shown in reference numeral 66, which is supplied to the liquid product 42 prior to treatment in the nanofiltration membrane separation system 56 by means of the tubular conduit 70. The addition of at least one antifouling composition 66 (Figure 1) will prevent the formation of calcium precipitates or other sparingly soluble salts (eg, CaS04, and / or CAC03) during nanofiltration. These precipitates can clog (e.g., contaminate) the selected nanofiltration membranes in the separation system 56, thereby reducing the operational efficiency of the entire processing system. The amount of composition against scaling 66 to be employed will depend on numerous factors, including, but not limited to, the chemical character of the liquid product 42, the pH of the liquid product 42, the amount of calcium dissolved inside the product. liquid 42, and other extrinsic factors. In this regard, preliminary pilot tests on the liquid product 42 of interest can be used to determine if antifouling compositions are needed, and how many antifouling compositions should be used. However, in a representative and non-limiting embodiment involving a situation where the use of a selected fouling composition 66 is guaranteed, typically from about 1 x 10 to 1 x 10 grams of the composition selected from the incrustations will be used. per liter of the liquid product 42. Again, this value can be varied as necessary. It should also be noted that the anti-fouling composition 66 can simply be added to the liquid product 42 in the above amount as a routine practice, without conducting preliminary analyzes of the calcium ion content thereof. Numerous materials can be used in connection with the anti-scaling composition 66, and the present invention will not be limited to any particular anti-fouling material. Exemplary compounds suitable for use as anti-scaling composition 66 include, but are not limited to, sodium hexametaphosphate and sodium polyacrylate in water (commercially available from the American Cyanamid Company of Wayne, NJ (USA) under the name " Cyanamer P-70"). When the calcium content of the liquid product 42 is >; > approximately 0.1 grams / liter, it is often required to "soften" the liquid product. "Soften" - the liquid product, is the reduction of calcium content by, more commonly, but not limited to, the precipitation of soda ash (NaC03) from calcium carbonate (CaC03), or by ion exchange methods. resin. This pretreatment of the liquid product to reduce the calcium content of the liquid product to approximately 0.1 grams / liter of calcium content therein, and consequently, to prepare the solution for treatments against the standard incrustations preceding the membrane separation treatment. of nanofiltration, is commonly required when lime (CaCO) has been added to process 10 before the nanofiltration membrane separation step, as for a pH control. Nanofiltration membranes will normally prevent the passage therethrough of materials (e.g., ions, particles, and the like) having a size (average diameter) which exceeds about 10 angstroms, more typically about 15 angstroms, and very typically about 20 agnstroms, and / or which are in a cyanide complex having a multivalent charge.

A rejection is made on the combined bases of atomic radii and electrostatic interactions between the ions and the membrane. The membrane passes water, chloride, hydrogen, hydroxyl, precious monovalent metal salts, and uncharged particles less than 2 nanometers in size. In contrast, ultrafiltration membranes will normally prevent the passage therethrough of materials having a size (average diameter) exceeding about 50-200 angstroms, regardless of the valence. In this case, the substantial difference in the filtration capacity between the nanofiltration membranes and the reverse osmosis membranes is even more important. Reverse osmosis membranes will normally prevent the passage therethrough of compositions having a size (average diameter) greater than about 2 to 5 angstroms, regardless of the valence. There is a significant and substantial difference _ between nanofiltration systems and other membrane technologies, including reverse osmosis. Regarding the separation characteristics, nanofiltration is located between reverse osmosis and ultrafiltration, and fills the "gap" that exists between these two technologies. The significant differences in capacity and operational ability that exist between nanofiltration membranes and reverse osmosis membranes include many things. For example, according to the aforementioned article, the nanofiltration membranes effectively operate at lower pressures of about 1.4 MPa / 200 psi, compared to the reverse osmosis membranes which normally have operating pressure requirements greater than about 4 MPa. Most commercially available nanofiltration membranes also have a very high membrane flux which makes it possible to operate at relatively low fluid pressures (e.g., 5.25-14 kg / cm). The term "membrane flow", as used herein, is defined as the flow rate / capacity of the materials through the selected membrane, as a function of the area of the membrane, for example, in liters per meter square a day ("LMD"). There are also differences in the types of materials that can pass through these membranes. The use of one or more nanofiltration membranes in the separation system 56 of the present invention provides numerous advantages, compared to other types of membrane, including reverse osmosis. These advantages include, but are not limited to, lower required operating pressures, higher flow levels, and reduced tendencies to contamination. In the same way, it has been discovered, in accordance with the present invention, that the nanofiltration membranes are particularly suitable (compared to other types of membrane) to effectively differentiate between the copper-cyanide complex and the gold-cyanide complex in the liquid product 42 generated inside the system 10, such that these materials can be separated from each other. The high degree of separation efficiency achieved by the nanofiltration membranes that involve the copper and gold species, results from the ability of these membranes to differentiate between metal ions based on the load, the scientific basis for this being currently unknown. capacity. For this reason, nanofiltration membranes are preferred for use in the separation system 56 of the invention, and represent a unique development in the gold processing technique, especially in the treatment of gold ore containing "impure" copper. A number of different nanofiltration membrane units commercially available in the separation system 56 (e.g., such as the nanofiltration membrane unit 64 shown in Figure 1). The representative nanofiltration membrane cartridge unit suitable for use herein is produced by Desalination Systems, Inc. of Escondido, California, under the name "Desal-5". This membrane unit is normally configured in the form of an elongated cartridge which is illustrated schematically in Figure 2 in reference numeral 100. Each cartridge 100 is typically about 101.6 centimeters long, and preferably between about 10.16 and 20.32. centimeters in diameter. The cartridge 100 includes a housing 102 having a first end 104 and a second end 106. The first end 104 and the second end 106 are both open, so that the fluids can pass through the housing 102. At the center of the cartridge 100 there is an elongated conduit 110 having numerous openings 112 therethrough. Surrounding conduit 110, there are multiple spirally wound layers 114 of filter membrane material, which are proprietary in their structure and chemical composition. Also, associated with the layers 114 of filter membrane material, are the layers 116 of a porous spacer material (e.g., a plastic mesh / proprietary polymer), and the layers 120 of a porous membrane backing material example, also made of a proprietary porous plastic composition), to which the layers 114 of the filter membrane material are fixed. In use, the fluid to be treated (e.g., liquid product 42) enters the first end 104 of cartridge 100 in the direction of arrow "X". The selected fluid is not allowed to enter the elongate conduit 110, which is designed to receive the filtered permeate as described below. As a result, the inlet fluid (liquid product 42) passes between and through the layers 114 of the filter membrane material. A retentate is formed between the layers 114 of filter membrane material, which consists of materials that can not pass through the layers 114 (for example, the copper-cyanide complex in the liquid product 42, as further discussed further. ahead) . In contrast, liquids and other materials associated therewith (eg, the gold-cyanide complex of the present invention), which actually pass through layers 114 of the membrane material, layers 116 of spacer material, and the layers 120 of backing material are collectively designated as the permeate. The permeate finally enters the duct 110 through the openings 112 therethrough. It should be noted that the permeate flows inward towards the duct 110 in a "Y" direction, which is perpendicular to the direction of the "X" arrow. As a result, the permeate is allowed to exit the conduit 110 at the second end 106 of the cartridge 100 in the "arrow direction" P. "The retentate flows along and between the layers 114 of the filter membrane material, and it finally exits the cartridge 100 at the second end 106 thereof, in the direction of the "R" arrow.The retentate flow in this manner (which is conventionally characterized as "cross-flow" filtration) is facilitated by fluid pressure continuous exerted on the system by the fluid input materials (eg, the liquid product 42) As mentioned above, the cartridge 100 illustrated in Figure 2 is available from Desalination Systems, Inc. of Escondido, California, under the name "Desal-5." However, other commercially available system / cartridge units of nanofiltration may be used in connection with the present invention, including, but not limited to, those produced by Osmonic. s, Inc. of Minnetonka, MN (USA) under the product designation "TLC type B"; Hydranautics, Inc. of Oceanside, CA (USA) [model 4040-TFV-74501]; and Film Tech, Inc., of Minneapolis, MN (USA) [model NF-45]. In accordance with the foregoing, the claimed invention will not be restricted to any particular type or configuration of nanofiltration units. Furthermore, as noted above, the number of cartridges 100 that function as the nanofiltration membrane units 64 in the separation system 56 can be varied selectively, depending on the type and amount of the inlet fluid (e.g., liquid product 42). ) that will be treated. For example, if 37,854 liters of the liquid product 42 having the composition values / ranges mentioned above are to be treated at an inlet flow rate of approximately 151 LPM, optimal results will be achieved if 18 cartridges are used. "Desal-5"100 in series, each cartridge 100 being approximately 101.6 centimeters long and approximately 20.32 centimeters in diameter. Likewise, in cases involving a relatively high input flow rate (for example, exceeding about 3,785 LPM or more), the liquid product 42 is preferably divided into a plurality of portions that are passed through. of a series of nanofiltration membrane units operated in parallel, followed by the passage of the liquid product 42 through a series of nanofiltration membrane units operated in series. This technique makes it possible to handle and treat relatively large initial feed streams more quickly and efficiently, without overloading the system 10. Although a number of different configurations of nanofiltration cartridge units can be employed for this purpose (not the present invention being restricted to any specific configuration), a representative system would involve first dividing the input liquid product 42 into two equal fractions. Each fraction would then be treated in a separate "branch" or step of the nanofiltration separation system 56. In a preferred embodiment, each stage would include two cartridges 100 (eg, of the type discussed above, including the "Desal-5" cartridges). in parallel, followed by two cartridges 100 in series. The retentates and the permeated from both "stages", would then come together again at the end of the separation process for an additional treatment, et cetera. However, this particular system represents a single non-limiting mode, a number of other nanofiltration systems having different configurations of cartridge units for use herein are also suitable.

Having presented a specific discussion of nanofiltration membrane technology, and its distinctive character in relation to other types of filtration membrane, including reverse osmosis membranes and ultrafiltration membranes, the unique capabilities of nanofiltration technology will now be described in relation to the claimed process. Specifically, by supplying the liquid product 42 to the nanofiltration membrane separation system 56 (e.g., the nanofiltration membrane unit 64), a retentate 130 is generated that does not pass through the nanofiltration membranes associated with the nanofiltration system. separation 56 (membrane unit 64), and a permeate 132 is produced which in effect flows through the nanofiltration membranes associated with the separation system 56. In a representative and non-limiting embodiment involving the preferred flow rates indicated above , the permeate 132 will optimally pass through the nanofiltration membranes of the separation system 56 (eg, using a single unit or multiple nanofiltration units), at a representative membrane flow rate of approximately 81.5 to 815 LMD. In addition, it is desired that the system 10 be capable of processing at least about 378 to 37,854 liters of the liquid product 42 per minute, which can be done in accordance with the numerical parameters mentioned herein. The retentate 130 comprises at least most of the copper-cyanide complex and other multivalent non-precious metal cyanide complexes, and some of the gold-cyanide complex and other monovalent precious metal cyanide complexes, while the permeate 132 contains at least most of the desired gold-cyanide complex, and little, if any, of the copper-cyanide complex and other multivalent non-precious metal cyanide complexes, both materials being effectively separated from one another using the separation system of nanofiltration membrane 56 (e.g., the nanofiltration membrane unit 64 shown in Figure 1). The retentate preferably comprises at least about 75 percent, more preferably at least about 90 percent, and still more preferably at least about 98 percent of the multivalent metal cyanide complexes in the impregnated leaching solution. Preferably, the permeate is substantially free of these complexes, and more preferably comprises no more than about 2 percent of the multivalent metal cyanide complexes in the impregnated leaching solution. Preferably, the retentate comprises at least about 5, and more preferably at least about 50 grams / liter, and the permeate not more than about 0.25 grams / liter, more preferably not more than about 0.1 grams / liter, and still more preferably not more than about 0.01 grams / liter of multivalent metal cyanide complexes. The permeate preferably contains at least about 75 percent, and more preferably about 90 percent, of the precious metal, while the concentrate preferably contains at least about 75 percent, and more preferably about 98 percent, of the metal base. Preferably, the permeate is substantially free of the multivalent metal cyanide complex or a multivalent metal cyanide complex concentration of at most about 250 ppm, and more preferably about 20 ppm. The filtration is conducted in such a way that most of the impregnated leaching solution is contained in the permeate 132. The retentate 130 preferably comprises no more than about 50 percent of the impregnated leaching solution 42, more preferably no more about 25 percent, and still more preferably no more than about 10 percent of the impregnated leaching solution 42. In contrast, the permeate 132 preferably comprises at least about 50 percent of the impregnated leaching solution 42, more preferably at least about 75 percent, and still more preferably at least about 90 percent of the impregnated leaching solution 42. Preferably, the permeate represents as much of the volume of the impregnated leaching solution as possible to maximize the recovery of precious metals. The monovalent precious metal cyanide complexes will not only pass through the filter, but will also be removed in the retentate, generally based on the volumetric proportions of the permeate and retentate. In accordance with the above, if the permeate constitutes 70 percent of the volume of the impregnated leaching solution, approximately 70 percent of the monovalent precious metal cyanide complexes in the impregnated leaching solution will be removed in the permeate, while approximately 30 percent will be removed in the retentate. For this reason, it is important to perform the separation in such a way that as much volume as possible is removed in the permeate, removing as little volume as possible in the retentate. Preferably, the volumetric ratio of the permeate to the impregnated leaching solution is at least about 1: 2, and more preferably is about 1: 5 to about 1: 1, and the volume ratio of the retentate to the impregnated leaching solution is not greater than about 1: 2, and more preferably is from 1: 3 to about 1:10. The membrane separation process is regulated by the osmotic pressure, that is, the separation process does not start until a critical operating pressure is developed through the membrane. Osmotic pressure is the concentration of dissolved dissolved solids that is reflected in the highest operating pressures for each stage in a separation circuit (for example, the first stage could remove 1/3 of the solution as permeate of fresh water, concentrating this way the copper-based metal ions in a stream of 2/3 of the volume, which, by definition, is more concentrated, and consequently, the next step of removing 1/3 of the water will necessarily be done at a pressure of the highest crossed membrane). The operating pressure used for the filtration preferably is at least about 7 kg / cm, and more preferably is about 7 kg / cm at about 56 kg / cm, and most preferably about 21 kg / cm to about 49 kg / cm2. It should also be noted that, if desired, according to the preliminary test procedures, the permeate 132 can optionally be refiltered (for example, it can be passed through another nanofiltration step) to further improve the purity of the permeate. 132. This can be done in the embodiment of Figure 1, by redirecting the permeate 132 back to the nanofiltration separation system 56 (e.g., the membrane unit 64) by means of the tubular conduit 136 shown in dashed lines in Figure 1. In an alternative manner, in situations involving large volumes of permeate 132 that are being generated in a high capacity system (for example, characterized by flow rates of approximately 3,785.4 LPM or more), it may employ an auxiliary nanofiltration separation system [not shown] separated from the main separation system 56 for this purpose. In a representative and non-limiting embodiment, an example helper system would involve passing the permeate 132 through two nanofiltration cartridges 100 (for example, of the type discussed above, including the "Desal-5" cartridges) in parallel, followed by two 100 nanofiltration cartridges in series. However, again it is important to emphasize that the use of an auxiliary separation system as described above, is optional, and is used on a basis as needed, as determined by many factors, including the chemical content of the permeate 132, and the overall operational capacity of the entire system 10. At this stage, insulation is now performed and the collection of the gold-cyanide complex (which resides inside the permeate 132). Subsequently, the gold-cyanide complex can be treated in any known manner to collect and refine the elemental gold therefrom, the claimed invention not being restricted to any subsequent methods of gold treatment / isolation. However, to provide a full disclosure of the present invention, a number of representative gold isolation techniques will now be discussed. There are a number of different approaches that can be used to treat the membrane permeate 132, so that elemental gold can be obtained therefrom. The representative processes, not limiting, suitable for this purpose, will now be discussed. One possible approach is the Merril-Crowe process discussed above. Specifically, the permeate 132 (which primarily comprises water in combination with the gold-cyanide complex) is combined with elemental zinc (Zn) according to the following reaction: 2Au (CN) 2-1 (ac) + Zn (g) - * 2Au (g) + Zn (CN) 4"2 (ag) Different lead salts (eg, lead acetate and / or lead nitrate) may also be added to the reaction process, as necessary in order to improve the efficiency of the zinc foundation process. In a representative and non-limiting embodiment, from about 0.003 to 0.015 grams of elemental zinc powder (typically having a particle size of about 40 to 400 microns) per liter of permeate 132, which contains the gold-cyanide complex, are used. in the same. With reference to Figure 1, the Merril-Crowe process is schematically illustrated. Specifically, a powder elemental zinc supply 138, having the aforementioned characteristics, is combined with the permeate 132, by means of the tubular conduits 139, 140. The resulting solid elemental gold resides within the reaction product of solid zinc-gold 142. This material is then routed through the tubular conduit 146 to a refining system 148 (illustrated schematically in Figure 1), which is used to obtain purified elemental gold from the reaction product 142. The fraction Liquid 150 is separated from the solid portions of the reaction product 142 in the refining system 148, using mechanical filtering devices and suitable settling / settling processes, and subsequently directed out of the separation stages of the refining system 148 by means of the tubular conduit 152. Then the liquid fraction 150 is transferred by means of the tubular conduit 154 back to the initial stages of the system 10 (for example, to the container 24 containing the leaching solution 22). The resulting liquid fraction (designated in reference number 150 of Figure 1) can be reused later in the system 10 as a source of valuable cyanide ions for the treatment of entry gold 12, which contains both gold elementary like copper. Because the copper-cyanide complex (which now resides in the membrane retentate 130) is not present in the liquid fraction 150, the free cyanide ions [(CN) -] in the liquid fraction 150 are not "bound" , and can effectively be reused to treat the input quantities of gold ore 12. Because the permeate 132 actually includes only about 1 to 5 ppm of gold therein (which nonetheless is a significant amount in that amount). the gold mining industry), a correspondingly small amount of elemental zinc 138 is employed in this process. As a result, only a minor (eg, negligible) amount of the aforementioned zinc-cyanide complex is produced. According to this small amount of zinc-cyanide complex (compared to the large amounts of copper-cyanide complex previously in system 10), as well as to the chemical differences between the zinc-cyanide complex and the copper-cyanide complex cyanide, the liquid fraction 150 containing the zinc-cyanide complex can be reused without the problems caused by the copper-cyanide complex. In the embodiment of Figure 1, the liquid fraction containing the valuable cyanide 150 is redirected back to the initial stages of the system 10, to be combined with fresh amounts of the cyanide-based leaching-solution 22, thus producing considerable cost savings. The "dehydrated" reaction product 142 is subsequently processed in the refining system 148 to isolate and remove the elemental gold therefrom. Again a number of different techniques for this purpose can be employed within the refining system 148, which will not be restricted to any method. For example, after washing with water to remove residual free cyanide ions and any remaining Zn (CN) complexes, the reaction product 142 can be combined with sulfuric acid (H2SO4) in the presence of air in the refining system 148, to dissolve the excess of elemental zinc (unreacted), and other metals, including copper and cadmium. Subsequently, the remaining solid materials are washed with water again and dried. If it is determined, by preliminary experimental analysis, that the resulting solid product contains substantial amounts of mercury (Hg), then the product can be further processed in a conventional mercury retort at about 400 ° C, to release the residual mercury to a assemble condenser, which is optimally placed under water to prevent the release of vaporized mercury into the atmosphere. The sludge type reaction product 142 can be heated in place in air to form zinc oxide (ZnO) from the residual elemental zinc, which is subsequently sublimated. The solid product containing elemental gold resulting from the aforementioned processes can then be melted into the refining system 148 in combination with a selected flow composition, which is designed to oxidize any remaining elemental zinc (as well as other residual metals that do not be gold), and in this way assist in the removal of metal oxides. Representative flow compounds suitable for this purpose include, but are not limited to, "borax" (e.g., Na4B4O-7 »10H2O), and silica (e.g., SiO2) in combination. It should also be noted that, although the refining system 148 discussed above basically involves the steps of: (1) filtration ["dehydration"]; and (2) casting, the system 148 in the same manner may incorporate a number of different steps. The term "refining", as used in connection with system 148, will therefore encompass a variety of different processes that can be used to produce the final elemental gold product 156. Another method of interest in the treatment of membrane permeate 132 that has the gold-cyanide complex, is the process of activated carbon. The activated carbon process is illustrated schematically in Figure 1 within the dotted frame 170. The membrane permeate 132 containing the gold-cyanide complex is placed in direct physical contact with a supply of activated carbon 172 via the ducts. tubular 174, 176 (Figure 1). Although not shown in the schematic representation of Figure 1, this step usually occurs in large column type structures. The term "activated carbon", as used herein, involves carbon materials in particles having an amorphous character, with a large surface area, and a considerable number of pores or "activation sites." Activated carbon can be obtained from the singeing of coconut shells or peach seeds at approximately 700-800 ° C, and will normally have the following optimum parameters: (1) surface area = 1050-1150 square meter / gram; (2) bulk density = 0.48 grams / cubic centimeter; (3) particle density = 0.85 grams / cubic centimeter; (4) voids in the densely packed column = 40 percent; and (5) representative particle sizes = mesh minus 6 - plus 16, or mesh minus 12 - plus 30. However, the claimed invention (and the activated carbon adsorption processes in general), will not be restricted to these particular parameters , which are provided for example purposes only. Once the membrane permeate 132 containing the gold-cyanide complex comes into contact with the activated carbon 172, an adsorption process is presented which is not yet fully understood. Specifically, the gold-cyanide complex (which is defined herein to encompass aurocyanide ions, ie, Au (CN) 2) is adsorbed on the surface of activated carbon 172, using a number of theoretical mechanisms, including the possible presence of multiple "surface oxide sites", which make it possible for adsorption to occur. In general, the activated carbon supply 172 that is used in this method is operated in a "fluidized bed" mode, which can be achieved through the use of a representative flow rate of approximately 1.019 LPM / square meter, associated with coal-containing columns, when coal 172 of mesh minus 6-plus 16 is used. When coal 172 of mesh minus 12-plus 30 is used, a flow rate of about 611 LPM / square meter is preferred. Both parameters will normally result in a bed expansion of approximately 60 percent. Although this embodiment of the claimed invention will not be restricted to any particular amount of activated carbon 172 (which will be determined in accordance with routine preliminary testing), a representative and non-limiting example will involve the use of approximately 2.5 to 10 grams of activated carbon 172 having the physical characteristics mentioned above) per liter of the permeate 132. Regardless of which mechanism ultimately results in the adsorption of the gold-cyanide complex on the activated carbon 172, this approach effectively removes the gold-cyanide complex from the permeate 132 , and generates a carbon product containing gold 180 schematically illustrated in Figure 1. The carbon product containing gold 180 consists of coal 172 having the gold-cyanide complex combined therewith. This process also results in the generation of a "barren" (eg, separated) liquid fraction 182, which contains substantial amounts of water and free cyanide ions [(CN) ~], but which lacks a copper-cyanide complex and gold-cyanide complex in it. This liquid fraction 182 can subsequently be recycled and reused to treat the gold ore entry amounts 12. In the embodiment of Figure 1, the valuable liquid fraction containing cyanide 182 is initially separated from the gold product containing 180 gold, using conventional mechanical filtration devices or known settling / settling processes. Then the liquid fraction 182 is collected and transferred away from the carbon product containing the remaining "dehydrated" gold 180 by means of the tubular conduit 184. The liquid fraction 182 is subsequently redirected back to the initial stages of the system 10, to combined with fresh quantities of the cyanide-based leaching solution 22. As shown in Figure 1, the liquid fraction 182 is directed through the tubular conduit 186 back to the initial stages of the system 10 (eg, to the container 24). que_ contains the fresh leaching solution 22). Next, the carbon product containing "dehydrated" gold 180 is filtered again, to remove residual liquid materials therefrom, followed by "desorption" or removal of the gold-cyanide complex from the coal product 180. This is done using a selected eluent solution that is placed in direct physical contact with the carbon product containing gold 180. With reference to Figure 1, a supply of eluting solution 190 is combined with (e.g., passed through) the gold-containing carbon product 180, via tubular conduit 192. A representative eluent solution suitable for this purpose includes, but is not limited to, a, a NaOH-CaCN solution (eg, optimally from about 0.5 to 1.0 weight percent NaOH, and from about 0.1 to 0.3 weight percent NaCN containing about 20 percent ethyl alcohol) . In the same way, this solution is heated in a preferred embodiment at a temperature of about 77-120 ° C. The claimed invention will not be restricted to any particular amounts of eluent solution 190 that are determined in accordance with preliminary tests on the carbon product containing gold 180 that is being treated. However, in a representative and non-limiting embodiment, approximately 2 to 4 liters of the eluent solution 190 are typically used per kilogram of the gold product containing 180 gold (this amount being subject to adjustments, as necessary). It is theorized that the cyanide ions [(CN) ~] in the eluent solution 190 described above, effectively replace / exchange the adsorbed aurocyanide ions (gold-cyanide complex) that are released to the eluent solution 190. The eluproduct which contains resultgold 196 (which is in the form of a liquid, and comprises the gold-cyanide complex "released" therein), is then collected from the "separated" carbon product 180 by means of the tubular conduit 200, and is further processed to recover the elemental gold therefrom. The remaining "separated" carbon product (not shown) can be discarded or regenerated using conventional methods. At this point, the eluent product containing gold 196 is transferred via tubular conduit 202, to a refining system 204, which is schematically shown in Figure 1. The refining system 204 (which may involve a number of different treatment steps of conventional design), makes it possible to recover elemental gold from the eluent 196. In accordance with the foregoing, this embodiment of the invention will not be restricted to any particular methods, techniques, or processing equipment in connection with the refining system 204. For example, the isolation, collection, and recovery of gold within the refining system 204, can be performed using zinc precipitation according to the Merril-Crowe process as described above, although the conventional electrolytic extraction methods as part of the refining system 204. Once the process is finished of electrolytic extraction. Cathodes containing elemental gold are removed from the system, and treated to recover the elemental gold from them. The cathodes in this step may contain up to about 50 percent or more gold thereon (eg, up to about 6.250 grams of elemental gold per kilogram of the cathode, if steel wool is involved). To process the cathodes, they can initially be placed in contact with sulfuric acid (H2S04) in an optional pre-treatment step, which is designed to dissolve residual metals that are not gold, including copper, iron, and the like. The need for a pre-treatment step with sulfuric acid is usually determined in accordance with preliminary pilot studies on the electrolytic extraction products (eg, cathodes) under consideration. If the cathodes contain substal amounts of mercury (which will not normally be removed by the sulfuric acid treatment), they can be subjected to conventional retorting processes, as discussed above. Then the cathodes are melted in combination with one or more selected flow compositions, which are again designed to oxidize the residual metals that are not gold, and in this way, assist in the removal of metal oxides. Representative flow materials suitable for this purpose include, but are not limited to, "borax" (e.g., Na4H4O7 * 10H O) and silica (e.g., SiO2) in combination. The refining system 204 may incorporate a number of other steps. The term "refining", as used in connection with system 204, will therefore encompass a variety of different processes that can be used to produce the final elemental gold product 206. Other representative methods that can be employed to collect and isolate the gold-cyanide complexes, followed by additional purification to produce elemental gold, include: (1) solvent extraction procedures, using phosphorus alkyl esters, as well as primary, secondary, tertiary, and / or quaternary amines (alone or combined with phosphine oxide, sulfones, and / or sulfoxides) to extract the gold-cyanide complex materials from the leaching solutions; and (2) ion exchange methods and compositions (eg, resins), wherein the aurocyanide ions are extracted from the leaching solutions, including the representative elution materials suitable for use in these compositions, sodium hypochlorite, zinc cyanide. , thiocyanate, a thiocyanate / dimethyl formamide mixture ("DMF"), and the like. Exemplary ion exchange resins that can be employed for this purpose, include those sold under the trademark DOWEX, and others that are commercially available from the Dow Chemical Company of Midland, MI (USA). Both methods of gold isolation (combined with conventional electrolytic extraction and smelting processes) represent alternative methods that can be used to isolate and collect elemental gold from the membrane permeate 132. The retentate 130 is specifically directed out of the separation system 56 via the conduit tubular 134, the permeate 132 directed out of the system 56 using the tubular conduit 135. The retentate 130 can be discarded, sent to an appropriate storage facility, or (more preferably) reprocessed as discussed in substantial detail below, to recover the elemental copper of it. In this regard, the present invention will not be restricted to any particular method, process, or use in connection with the retentate 130. As shown in Figure 1, if subsequent treatment of the membrane retentate 130 is desired, it can be directed by means of the tubular conduit 210 to a refining system 212, such that a final elemental copper product 214 can be generated. The refining system 212 can involve the addition of a selected acid (eg, sulfuric acid (H2SO4) ) to membrane retentate 130, which causes a precipitation reaction to occur, where the copper-cyanide complex is precipitated as solid (stable) CuCN, the "free" cyanide ions becoming [(CN)] to HCN, acj The basic reaction associated with this process is as follows: H2S04 (AC) + Cu (CN> 2_1 (ac) - S04 ~ 2 + 2HCN (ac) + CuCN (s) This process (which involves an example of a process that can be employed within the refining system 212) is specifically discussed in U.S. Patent No. 996,170, which is incorporated herein by reference. The solid CuCN can be subsequently treated according to a number of conventional methods to obtain the final elemental copper product 214. For example, representative procedures to achieve this goal include reduction-rowing with H2 gas to produce a "copper sand". ", which merges later. Alternatively, another method that can be employed in connection with the refining system 212, involves the combination of membrane retentate 130 with a selected acid (eg, sulfuric acid [H2S04]), and sodium sulfide (Na2S) , to produce a precipitate of Cu2S according to the following reaction: Na2S (s) + 2H2S04 (ac) + 2Cu (CN) 3-2 (ac) - > 2S04"2 (ac) + Cu2S (s) + 4HCN (ac) + 2NaCN (ac) Then the Cu2S precipitate can be melted to obtain the final elemental copper product 214 (Figure 1). In another embodiment, the metal recovery process generally includes the steps of: (a) contacting a basic leaching solution with a metal-containing material to form an impregnated leaching solution containing at least a portion of the metal (e.g. copper, zinc, cobalt, iron, calcium, magnesium, nickel, lead, cadmium, mercury, platinum, and palladium, and mixtures thereof with copper, with more Zn and Ni preferred), in the form of a dissolved multivalent complex and solids suspended; (b) filtering (for example, using one or more nanofiltration membranes) the leach solution impregnated with a filter to form a retentate containing at least the majority of the multivalent metal complex in the impregnated leaching solution, and a permeate; and (c) recovering the metal from the retentate, for example, by electrodeposition methods.

The permeate can be further treated to recover the monovalent metal complexes, if any, in the permeate, or is discharged. The multivalent metal complexes are concentrated in the retentate by approximately >; 2: 1, more preferably _ > 5: 1, and more preferably > . 10: 1, to a stream of "metal". The "impregnated" stream charged with __ complex of concentrated multivalent metal (ie, retentate), can then be used as a feed for the efficient recovery of metals by means of electrolytic extraction processes (electrodeposition), by direct electrodeposition of the metal from the metal retentate stream, by acidifying the metal (or concentrated) retentate stream preceding the recovery of metal in the coal, and the subsequent electrodeposition of the metal from the carbon eluate, by acidifying the _ stream of metal concentrate to form M (CN) s ¿0 (where M is metal), and resolution of the M (CN) as a high molar concentration feed to the electrodeposition cell, or by the treatment of the metal concentrate stream with a chelating agent before the electrodeposition. Each of these options of the metal electrodeposition circuit has associated intermediate processing steps to control the amount of cyanide present in the electrodeposition cell, as a means to control the losses by cyanide electrooxidation, and to improve the utilization of the current Faradic electrical, and the efficiency of the metal electrodeposition process. Each one of the metal electrodeposition circuit options has internal potentials of the electrodeposition circuit for additional filter treatments, in order to increase the metal content of the electrolytic extraction solution, to effect a better operation of the cell. Coincidental to any of the metal electrorecovery processes, it is the recovery of a significant fraction, usually greater than 70 percent, of the cyanide complexed with the metal. The invention can be used for the recovery of metals and cyanide from electroplating rinse waters, leaching liquors from the production of primary metals, and "eluent" leaching solutions from the production of primary metals (for example, the solutions of cyanide used to separate carbon). The dissolution of copper from the minerals containing malachite, chalcocite, covellite, cuprite, and bornite, by means of basic cyanide solutions (ie, from a Ph of approximately 10.5 or more), has been known for a long time. The charged leach solutions are called "impregnated" liquors (PLS), and are typically diluted, for example, < 2 grams of Cu / liter of leaching solution. The direct electrolytic extraction of copper from solutions of this diluted is not economical, due to the large size of the installation required to process the diluted current (called the space-time factor), and the low electrical efficiency of the cell (the low efficiency of the cell leads to a large energy consumption). The indirect electrolytic extraction of metals from diluted solutions, that is, the precipitation of the metals components of the diluted stream before the redissolution of the metals to be used in cells of high ionic concentration, requires large volumes of acid for the adjustment of pH, and in general it is not economical. The process of this invention uses filter membranes to purge the basic water from an impregnated liquor stream or any other current of cyanide charged with metal, in order to effect, in a coincidental manner: (a) a reduction in the volume of the current to be treated (which reduces the size of the downstream liquid treatment units); and (b) an increase in the metal concentration in the resulting metal-loaded basic stream to be treated (i.e., concentrated) by a factor of about > . 5: 1, more preferably from > . 7: 1, and most preferably from > . 10: 1 in the case of copper (the higher concentration of Cu improves the faradic efficiency of direct electrolyte extraction; being the faradic efficiency the measure of electrical current utilization of an electrorecovery process, and largely a function of the frequency of interfacial solid-ion contacts in a printed electric field, these interfacial contacts increasing in part in proportion to the ionic concentration of the solution being treated). Furthermore, it is demonstrated that the membrane filtration process, for reasons not completely understood, but which are believed to be related to an electrostatic adsorption effect, greatly reduces the volume of acid required to effect the pH changes of the solution in relationship with the acid typically consumed in a pH adjustment of the cyanide solution, if this pH adjustment is selected as the pretreatment for an indirect electrolytic extraction process. The reduced pH is a method commonly used for the selective recovery of copper and base metals such as M (CN) s two (as noted, "M" denotes the complexed metal). M (CN) s alone can be fed into an electroplating process of the electroplating type of a nearly constant metal concentration (in the electroplating anodes, the plating bath is dissolved at the electrodeposition rate of the metals in order to maintain a constant concentration of the metal ion, in the electrodeposition process "of electroplating type" described above, the ion source of metal for the bath at constant concentration, is the salt precipitate of M (CN) s üdos) • The generation of M (CN) s6] _j_dos from the solution impregnated with membrane, therefore, is made possible economically with a reduced acid consumption. The electrorecovery process in the electroplating type electrodeposition is of high efficiency, because the M (CN) sj_icios can be dissolved in the solution of electrorecovery bath in high molar concentrations, which improves the faradic and space efficiencies -weather . In one embodiment of the invention shown in Figure 3, that of primary or secondary metal ore treatments (glues), the ore would be leached in a stack or in a tank 310 using conventional industrial practice, with cyanide solutions strong enough to dissolve the metal. The result of the leaching is an "impregnated leaching solution" (PLS) 314. The PLS 314 would be classified318, as through a filter of approximately 1 to 10 microns, and would pass, at a higher pressure than the osmotic one, through a filter membrane 322, for: (a) effecting the rejection of the copper or other multivalent metal complexes towards the reduced volume membrane "concentrate" 326, and ~ (b) passing the permeate 330 into the processing step of permeate or towards the discharge. The membrane processing step decreases the volume of the metal-loaded solution (now termed "metal impregnated"), with substantially no loss of metal to the permeate (the metal impregnated exhibits an increased metal content of 2 times to 10%). times or more, measured by the concentration in parts per million, in relation to the gross PLS). The metal impregnation can be introduced directly into the circulating catholyte of an electrolytic extraction cell 334, or it can be conditioned with acid to recover the metals (at a pH of preferably from about pH 3 to about pH 6, and more preferably at about a pH of 4), or the cyanide, and then reconditioned at a pH that is preferably from about pH 9 to about pH 11.5, and more preferably about pH 10.5, before being introduced into the circulating catholyte of electrolytic extraction cell 334, or optionally, can be conditioned with acid 338 to a pH of preferably from about pH 1 to about pH 3, and more preferably about pH 2, with or without intermediate recovery of base metal precipitates other than copper, is filtered (such as by ultra- or micro-filtration) for recovery of Cu (CN) precipitate , and the precipitate is introduced to the circulating catholyte of a cell of electroplating type (preferably operated at, or greater than, a metal concentration level 1M). The impregnated metal 26 is mixed in a circulating catholyte of a higher concentration of metals than the impregnated metal itself, or optionally, a precipitate impregnated with metal in a circulating catholyte is mixed, and flows through an electrolytic extraction cell. to effect the recovery of metals (the metal electrorecovery cell can be, but is not limited to, an extended area cathode, an anolyte catholyte cation exchange membrane, or a separate type of porous diaphragm, to minimize space-time loads and the anodic oxidation of the CN The recovery of cyanide 341 is carried out by means of the volatilization 343 of the acid-treated stream, for the removal of the dissociated CN After achieving the recovery of metals in the electrorecovery cell, a volume of catholyte 342 would be expelled from the circuit, to purge free cyanide (CN-) and the base metals (if the base metals were not purged by selective precipitation previously in the processing). In the case of direct electrolytic extraction of the metal impregnation (ie, without the intervening step of the change of state of the metal from aqueous to solid induced by the pH before the electrodeposition), the ejected volume is equal to the volume of the impregnated metal. initially introduced. Expelled volume is treated to sweep the metal, if the metal is present in the stream (the metal sweep can be, but is not limited to, by recovery with resin, by acidification and recovery of metal cyanide in coal, recovery by membrane filtration, recovery in a metal chelating agent or other metal recovery processes, for example solvent extraction). The metals recovered from the ejection stream would be introduced into the circulating catholyte. In the electrodeposition process from cell solutions in high metal concentrations, based on the constant addition of the metal cyanide precipitate, the volume of the expelled solution is much smaller than that required to be expelled when it is electrodeposited from the cells. electrolytic extraction of impregnated metal feed from lower metal concentration. Typically, less than about 5 percent of the cell solution should be expelled from the metal impregnated precipitate electroplate cells, and the expelled solutions can be redirected to the incoming metal impregnation for recovery. and metal recycling (ie, the acidification process of metal impregnation treatment serves both as the solution ejection path for controlling the cyanide: metal ratio by volatilization, as well as for metal recovery). The impregnated metal and the impregnated metal precipitates can be electroprocessed for the recovery of copper in a small space-time installation in relation to an installation designed to electroprocess the crude PLS, with an unconcentrated membrane. However, the reduced efficiency of the electrorecovery processes at high levels of CN: metal, makes impractical a recovery greater than about 10 percent to 40 percent of the metal in a single pass through a cell (in a proportion of CN: metal of approximately more than 4: 1, the electrorecovery process ceases completely, and because three moles of CN are released to the electrorecovery solution for each mol of metal recovered as electroplated metal, the proportion of the CN solution Metal accumulates rapidly during the electrorecovery process, therefore, it is more economical to introduce the metal impregnation into a volume of catholyte circulating with a higher concentration of metal ion, for example, if the circulating catholyte is of a volume equal to impregnated metal, and four (4) times higher in the concentration of metal to the mixing stream of impregnated metal input, the Total metal flow from the inlet metal impregnation stream can be gained with a high faradic efficiency in a single pass through the cell. In another embodiment shown in Figure 4, the impregnated metal 326 is acidified 345 to a pH of about a pH of 4 to about a pH of 8, to precipitate the base metals, such as Zn (CN) 2, is subjected to solid / liquid separation 347 to recover the precipitates, the liquid impregnated 348 is contacted with a base at a pH of about a pH of 9 to about a pH of 10.5, and the liquid impregnated (for the precipitation of metals and the recovery from the current) 346 is introduced into an electrolytic de-cell 350 catholyte, which is concentrated in nanofilter 354 after passing through the cell (the NF process allows at least most of the metal content of the stream is recovered towards the NF retentate to be reused in the cell, while the required volume 358 of catholyte is ejected simultaneously in the NF-permeate to maintain the water balance of the electrolytic extraction cell. The highest faradic efficiency and the smallest space-time cost for the recovery of metals by electroprocesses are evidenced by the use of M (CN) solutions? of high concentration. These solutions can be artificially constructed by dissolving M (CN) s j_id0 in appropriately concentrated CN ~ (cyanide free) solutions. Through the processes of this invention, the recovery of M (CN)? from metal impregnation by acidification, less acid is consumed by unknown processes, but it has been empirically demonstrated that, therefore, these more efficient metal electrorecovery processes can be used (M (CN) s supply) _j_¿0 to a cell operated at and / or close to the saturation levels of M (CN)).

The impregnated metal 326 is conditioned with acid 366 to a pH of preferably from about a pH of 4 to about a pH of 6, and more preferably about a pH of 5, to: (a) facilitate the recovery-volatilized of WAD CN 367, and (b) reduce the M (CN)? to a lower state (for example, complexes of Cu (CN) and Cu (CN) 4 to the Cu (CN) 2 state). The exhausted CN- and WAD CN expelled solution 368, would then be conditioned with lime to a pH of preferably from about pH 9 to about pH 11.5, and more preferably about pH 10.5, and would be passed through. a bed of activated carbon to effect the selective recovery of the metal content M (CN)? (for example, for copper such as Cu (CN) 2) (the other base metal cyanide complexes in the extruded portion of the electrolytic extraction solution are generally not recovered in the coal to any appreciable extent). The expelled solution, after being exposed to carbon, can be discarded (or reused elsewhere, as in primary leaching). The metal (ie, copper) fixed to the carbon would elute at ambient temperature and pressure with a fresh cyanide solution. The copper-loaded eluate would be re-introduced into the recirculating catholyte, or optionally reconcentrated to a high molar level, such as through a nanofilter treatment step, and the entire process of adding Cu impregnation, electrolytic extraction, and so on. , it would start again (in industrial practice, the process of the invention will be continuous). For impregnation solutions of Cu previously treated for the removal of base metals (for example, by acidification 338 and selective precipitation), the expelled volume of catholyte can be permeate 362 of a nanofilter process 354 (the WAD CN of the system would be purged). by acidification-volatilization-regeneration (AVR) of the NF concentrate). In a similar manner, the acidification of the stream impregnated with Cu for the recovery of the Cu (CN) precipitate, can effect the selective recovery of M (CN) ?. Referring to Figure 5, in yet another embodiment of the invention, the metal-impregnated or retentate 326 is conditioned with acid 504 to a pH preferably from about a pH of 4 to about a pH of 8, to precipitate the base metals , such as zinc, is subjected to solid / liquid separation 508 to remove precipitate 512 from liquid 516, is further conditioned with acid 52Q to a pH of preferably from about pH 1 to about pH 3, to precipitate others base metals, such as copper, and subjected to further solid / liquid separation 524, to form a second precipitate 528, which is preferably comprised of copper-cyanide, and a second liquid 532. The second liquid 532 can be placed in contact with a base 536 to raise the pH to about pH 9 to about pH 10.5, and recycle. The first and second precipitates can be subjected to additional recovery steps. For the copper-cyanide as the second precipitate, the second precipitate 528 is contacted with a catholyte 540 in a mixing step 544, and the rich catholyte containing dissolved copper is subjected to electrolytic extraction in an electrolytic extraction cell 548. In yet another embodiment shown in Figure 6, the impregnated metal 326 is acidified 604 to a pH preferably from about a pH of 5 to about a pH of 7, with a pH of about 6 being more preferred, to effect a change or reduction of speciation of metal cyanide (for example, for copper, from Cu (CN) 3 and Cu (CN) 4 to Cu (CN4 to Cu (CN) 2) Cyanide 612 dissociated from] metal 608 can be recovered from the acidified solution by conventional volatilization-regeneration methods for re-use (the decomposed cyanide is called WAD cyanide.) After the recovery of WAD 608 cyanide, the solution rich in M (CN)? 616 620 can be reconditioned to a pH of preferably from about pH 9 to about pH 10.5, with a pH of about 10 being more preferred, and in the case of copper like metal, it is passed through a bed of activated carbon 624 to sequester copper. The sequestered copper can be diluted from the carbon using an eluate 628 to form an impregnated eluate 632, to be used as a feed to an electrodeposition cell 636, or preferably, it is concentrated in nanofilter 640 (after solid / liquid separation). of carbon 644) before introduction to the recirculating catholyte of the electrodeposition cell 636. The retentate 636 which contains at least most of the copper in the impregnated eluate 632, is contacted with the catholyte, while the permeate is recycled 648. The spent catholyte 652 after electrolytic extraction, 656 is acidified to a pH preferably from about pH 4 to about pH 7, with a pH of 5 being more preferred to form HCN, and HCN recovered 660 dispersing the catholyte with a 664 gas, such as air. The cyanide-drained catholyte 668 is contacted with a base to raise the pH to a preferred scale of about a pH of 9 to about a pH of 10.5, with a pH of 10 being more preferred. In a further embodiment shown in Figure 7 , impregnated metal 326 is treated 704 with a suitable chelated agent 708 (e.g., EDTA (ethylenediaminetetraacetic acid)) to form a chelator-metal complex dissolved in a chelated solution 712. Cyanide displaced by metal chelation it can be recovered by acidification 716, as noted above to form HCN, by dispersing the acidified solution 720 with a gas 724 to recover the HCN 728, by contacting the drained cyanide solution 732 with a base 736 to raise the pH preferably to approximately a pH of 9 to approximately a pH of 10.5, more preferably a pH of 10 being preferred, subjecting the cyanide drained solution to electrolytic extraction in a an electrolytic extraction cell 740 to form a metal product 744 and a spent catholyte 748, and finally by subjecting the spent catholyte 748 to nanofiltration 752, to form a retentate 756 containing at least the major part of the chelator, and a permeate containing little, if any, of the chelator. The chelator in the retentate can be reused, and the permeate can be purged for maintenance of the water balance of the cell. In yet another embodiment shown in Figure 8, the impregnated metal 326 is acidified 804 as noted above, to form HCN, the acidified solution 808 is dispersed 812 with a gas 816 to recover the cyanide 820, the cyanide drained solution 824 it is contacted with a base to raise the pH preferably to about a pH of 9 to about a pH of 10.5, with a pH of 10 being more preferred, is subjected to electrolytic extraction 828 (in a diaphragm cell or in a cell that have the anodic and cathodic compartments separated by an ion exchange membrane). In the case of copper, the metal in the realcalized solution will be predominantly Cu (CN) 2. Prior to the electrolytic extraction, the real-located 832 solution is mixed with a similarly acidified-volatilized-realcalized metal-rich circulating catholyte, and passed to the electrolytic extraction cell. A portion of the metal in the feed catholyte of the mixed electrolytic extraction cell is electrodeposited, consistent with the approximately 4: 1 ratio of CN: metal (ie, copper), characteristic of electrolytic extraction from solutions of cyanide. After electrolytic extraction of the appropriate amount of metal from the solution, the spent 836 catholyte is nanofiltered 840 to a rich retentate in metal 844 and a metal-poor permeate 848. The metal-poor permeate 848 is substantially equal in volume to the metal retentate 844 originally incident in the process. The metal-rich retentate 844 is recirculated and mixed with the solution containing fresh inlet metal before acidification-volatilization-realkalization and reintroduction into the electrolytic extraction cell. This modality makes possible particularly effective leaching mining by the cost of: (1) metal ores that are base and acid consumers (acid lixiviation being the conventional state of the art for the recovery of metal from minerals of these types), - (2) assemblies of metal ore that are refractory to acid, but susceptible to dissolution with cyanide, especially calcite minerals; and (3) metal ores containing precious metals that can be dissolved by cyanide (including cleaner tails, a "waste" generated by conventional copper recovery processes by flotation which, through the process of this invention, now become a "secondary" mineral). The rating is based on efficient and effective recovery for the cost of base metals, especially copper, and base metal and cyanide complexed by direct electrolytic extraction, and indirect electroplating type electrorecovery processes (precipitation with acid-feed from precipitate cell). The rating, in all the modalities, uses this invention of membrane segregation of, and coincidental concentration of, copper and base metal ions, up to a "concentrate" of small volume membrane suitable for a direct electrolytic extraction effective for the cost. Also, in ways that are not currently understood, but that are assumed to be related to the effects of electrostatic adsorption on precipitation processes, the invention reduces the consumption of acid for the preparation of metals from membrane concentrate solutions. . The precipitates then become the solid feed of M (CN) to an electroplating type metal recovery cell. In still another embodiment, the process includes the steps of: (a) filtering (for example, through one or more nanofilters) the impregnated solution to form: (i) a permeate that contains most of the precious metal, and ( ii) a retentate (or concentrate) that contains most of the non-precious metals (or interferentes of the spectator ion); (b) subsequently removing the liquid (e.g., water) from the permeate to form (i) a second retentate or "superimpregnated" having a concentration of precious metal that is greater than the concentration of precious metal in the permeate, and (ii) ) a barren (or second permeate) solution that includes most of the liquid in the permeate; and (c) recovering the precious metal from the concentrated solution. The precious metal can be gold or silver, and mixtures thereof. The metal can be any metal that forms a multivalent complex in the impregnated solution, for example copper, cobalt, zinc, iron, lead, nickel, calcium, magnesium, cadmium, mercury, platinum, palladium, and mixtures thereof. The removal of water from the permeate can be done by passing the permeate through a filter, such as a reverse osmosis concentrating device that passes water but not the complexed precious metal. Sufficient water is removed, such that the volume ratio of the permeate to the second retentate is preferably at least about 1: 1, more preferably at least about 3: 1, and most preferably at least about 9: 1. The concentration of precious metals in the second retentate is at least about 200 percent, more preferably at least about 900 percent, and most preferably at least about 1900 percent of the concentration of precious metals in the permeate . In other words, at least about 37.5 percent, more preferably about 50 percent, and most preferably at least about 90 percent of the water in the impregnated solution is contained in the waste solution. Commonly, the concentration of precious metals in the concentrated solution is at least about 0.002 grams / liter, more preferably at least about 0.02 grams / liter, and most preferably at least about 0.1 grams / liter. In the precious metal recovery step, the concentrated solution can be treated by a variety of processes, such as electrolytic extraction, acidification / electrolytic extraction, carbon recovery, precipitation with zinc, and extraction with solvent-electrolytic extraction, preferring electrolytic extraction, acidification / electrolytic extraction, and extraction with solvent-electrolytic extraction. The retentate can be treated to form one or more base metal products by suitable methods, including precipitation techniques, electrolytic extraction, and solvent extraction-electrolyte extraction. The "permeate" of reverse osmosis, cleaned of precious metals, remaining, is passed back to the front end of the process train to be reused (for example, back to leaching), or to be discarded. The process overcomes the problem of the spectator ion found in many precious metal refining techniques, such as the recovery steps of precious zinc or carbon metals, and electrolytic extraction. The process of the present invention provides for the selective recovery of precious metals and non-precious metals from mixed non-precious-precious metal solutions. The resulting precious metal and / or non-precious metal products may have relatively high purity rates. The process is highly efficient and economical. Although the process preferably uses electrolytic extraction to recover the precious metals, the relatively small volume of the concentrated solution provides a low space-time factor / cost in the electrolytic extraction cell. (ie, a relatively small cell can be used to contain the solution in order to effect the retention time required for migration of the gold ion to the cathode). Due to the small volume of the concentrated solution, and the high concentration of precious metal in the solution, the current efficiency and recovery rates of the electrolytic extraction process are relatively high, and relatively small amounts of energy are consumed during the electrodeposition cycle. The reagent costs in the acidification / electrolyte extraction techniques are relatively low (ie, the acid and lime consumptions for the pH adjustments are relatively low), due to the relatively small volume of the concentrated solution. Finally, through the steps of filtration and water removal, the process can omit undesirable steps of intermediate carbon concentration before electrolytic extraction. In accordance with the above, the process does not suffer from loss of precious metal in intermediate steps of coal concentration. The super-impregnated is substantially free of interfering ions if the ionic separation of nanofilter membrane is 100 percent efficient. However, as is common in industrial processes, the nanofilter segregation of interfering bystanders will be less than 100 percent efficient, and some non-precious metals will contaminate the permeate of the nanofilter. The permeate loaded with precious metals and slightly contaminated with non-precious metals, after the membrane concentration of reverse osmosis, will produce a reverse osmosis concentrate (the super-impregnated) that will contain essentially all (ie, normally at least approximately the 95 percent, and more typically at least approximately 98 percent) the precious and non-precious metals present in the reverse osmosis nanofilter permeate The presence of non-precious metals in the super-impregnated will interfere with efficient production of precious metals of high purity, by the recovery processes of precious metals of zinc and coal (the difficulty of producing the pure product from the super-impregnated is a function of the degree of its contamination with non-precious metal). , the recovery with zinc and coal of the precious metals from the super-impregnated created by the Subsequent processing of solutions impregnated by the first and second filtration steps, although possible, is not the preferred path towards the development of the pure product. Rather, the preferred super-impregnated treatments are direct electrolytic extraction, acidification-extraction-electrolytic, and extraction with solvent-extraction ^ electrolytic, which allow the selective recovery of precious metals from mixed solutions of non-precious metals- precious metals. As noted, direct electrolytic extraction of precious metals from dilute, non-concentrated impregnated solutions is seldom done, because: (a) the space-time factor is excessive (ie, the large cell required for containing the solution in order to effect the retention time required for the migration of the gold ion to the cathode, results in capital costs of uneconomically large equipment), and (b) the current efficiency of the electrolytic extraction process from of diluted solutions is extremely low (eg, typically from 1 percent to 3 percent), and large amounts of energy are consumed during the electrodeposition cycle. The electrolytic extraction from an eluate after the recovery of the precious metals in, for example, coal, is a common practice in the industry. Precious metals are lost in this intermediate step of concentration in coal, and consequently, less precious metal is recovered, and the presence of interfering metal ions in the carbon eluate degrades the product quality of the electrochemical extraction. In electrolytic acidification-extraction, the base metals are selectively precipitated from an impregnated solution, such that the precious metals are fed alone to the electrolytic extraction cell. For dilute, non-concentrated impregnated solutions, the consumption of acid and lime (for downward and upward pH adjustments, respectively) by this method are uneconomically large. Also, there is still the problem of the great cost related to the space-time of the electrolytic extraction cell. By the process of this invention, that is to say, that of the separation of non-precious metal ions, and the subsequent concentration of the permeate to a super-impregnated of -small volume and high content of precious metals, the direct electrolytic extraction of the metals precious from the super-impregnated, or extraction with solvent-electrolytic extraction of precious metals from a super-impregnated solution, or acidification-electrolytic extraction of precious metals from a super-impregnated with a high content of non-precious metals (for example, for impregnated liquors that are not efficiently nanofiltered), can be used because: (1) the space-time costs for the electrolytic extraction cell are greatly reduced by concentrations highest of precious metals and the smallest volumes of solution being treated, or (2) in the case of the acidification-extraction method In contrast, the aforementioned reduction of space-time cost reduction is combined with small e-waste and lime consumption (for pH adjustment downwards and upwards, respectively), due to the small volume of solution being treated. By the preferred processes of this invention, the nanofiltration purges at least about 50 percent, and more preferably about 90 percent of the volume of the crude impregnated solution into the permeate, and the reverse osmosis process purges at least about 50 percent. percent, and more preferably at least about 80 percent of the permeate to the second permeate, to produce a super-impregnated that is about 10 percent, and more preferably about 4.5 percent or less of the volume of the impregnated solution gross diluted input. The super-impregnated also has approximately 20 times more precious metal content than the diluted impregnated inlet solution. That is, the super-impregnated typically has a precious metal content of at least about 0.002 grams / liter, more typically at least about 0.02 grams / liter, and most typically at least about 0.1 grams / liter. In combination, this volumetric reduction of the feed to, and the concentration of the value of the precious metals of the product in, the electrolytic extraction cell feed, makes direct electrolytic extraction, acidification-electrolytic extraction, and extraction with solvent-extraction electrolytically, are economically practical for the recovery of pure precious metals of high quality. Referring to Figure 9, minerals that have gold are mined, crushed, and leached 910 using a diluted cyanide solution, thereby creating an impregnated leaching solution (PLS) 914; the PLS 914 is filtered 918 through a filter of approximately 1 to 10 microns to effect the removal of dirt and debris; the filtered PLS 922 is preferably passed through a membrane separation process of nanofilter 926, to effect the recovery of the non-precious metals to an "impregnated non-precious metal" 930 of about 1/3 or less of the original volume of the PLS, or more preferably up to about 1/10 of the original volume of the PLS or less, and the precious metals up to a "precious metal impregnation" 934 of a volume approximately equal to the rest of the filtered PLS 922 (The recovery of precious metal into the stream impregnated with precious metals is in direct proportion to the proportion of the division of the "permeate" (impregnated with precious metals) / "retentate" (impregnated with non-precious metal) made by the membrane. impregnated with non-precious metals 930 can be discarded or reused in the leaching operation, if it is disposed of, a "sweeping" precious metal assembly (for example, a carbon or resin column) would be optionally used to recover the metal value precious in the stream impregnated with non-precious metals); the impregnated precious metals 934 would be treated by reverse osmosis (RO) 938 to purge at least about 75 percent of the water, and more preferably 95 percent or more of the water, of the stream impregnated with precious metals (the purged water , the reverse osmosis permeate is recycled to the operation, or discarded, this membrane treatment sequence effectively concentrates about 60 percent or more, and more preferably about 90 percent or more, of the precious metal of the flow feeding the original PLS to the "super-impregnated" stream 942 by about 1/6 or less the size of the filtered PLS 922, or more preferably up to a stream of about 1/20 or less the size of the filtered PLS 922; and the precious metal would be extracted as the refined metal by, but not limited to, direct electrolytic extraction, precipitation with acid-extraction electrolyte, or extra solvent-electrolyte extraction 946. In yet another embodiment, an eluent containing the cyanide is subjected to the following steps: (a) filtering the effluent to form a concentrate containing most of the cyanide in the effluent, and ( b) contacting the concentrate with light and an oxidant to photocatalyst the oxidation of the cyanide to a cyanate. By concentrating the cyanide before performing the photocatalyzed oxidation, the amount of oxidant consumed is significantly less than that required for the photocatalyzed oxidation of more dilute cyanide solutions. The process is not limited to the photocatalyzed oxidation of cyanide, but is applicable to any process to convert cyanide to cyanate. In the filtration step, it is preferred that the filtration be performed using a nanofilter. Filtration is generally highly selective. The concentrate preferably includes at least about 95 percent, and more preferably about 98 to about 100 percent of the cyanide (and complexing metal) in the effluent, while the permeate preferably includes no more than about 5 percent, and more preferably from about 2 percent to about 1 percent of the cyanide (and complexing metal) in the effluent. The concentrate preferably constitutes no more than about 25 percent by volume, and more preferably no more than about 10 percent by volume of the effluent. Preferably, the oxidant is hydrogen peroxide. The amount of oxidant that comes in contact with the concentrate preferably is at least about 100 percent, and more preferably is about 100 to about 200 percent of the stoichiometric amount required to react with the cyanide in the concentrate. To provide efficient cyanide filtration, cyanide, especially free cyanide, in the effluent is preferably contacted with a metal to form a multivalent metal cyanide complex. The preferred metals are selected from the group consisting of copper, zinc, nickel, iron, and mixtures thereof. The amount of metal that comes into contact with the effluent of preference is at least about 100 percent, and more preferably at least about 150 percent of the concentration of free cyanide in the effluent. The concentrate usually includes at least about 98 percent of the metal in the effluent. To adjust the calcium concentration, the effluent may be contacted with a calcium precipitant, such as soda ash, or an ion exchange resin. Calcium is removed to prevent calcium sulfate and calcium carbonate from precipitating, and clog the filter. The preferred maximum concentration of calcium in the concentrate is about 300 ppm, and in the effluent is about 10 ppm. In order to further concentrate the cyanide in solution, the concentrate can be subjected to acidification-volatilization, and in some cases neutralization. In this process, sodium sulfide (Na2S) is added to the concentrate, and the concentrate is acidified to reduce the pH to no more than about a pH of 3, which causes the cyanide to become unstable in solution, and the sulfides of metal (for example, copper sulfide) are precipitated from the solution. A gas (eg, air) is dispersed through the concentrate to form cyanide gas, which is removed from the concentrate. The cyanide gas in the outlet gas is solubilized in solution by known techniques, such as by scrubbing with sodium hydroxide or milk of lime. In this way, the concentration of the cyanide in the solution exceeds the concentration of cyanide in the concentrate, thereby providing additional reductions in the oxidant consumption. Referring to Figure 10, a waste stream 1004 contaminated with free cyanide and / or cyanide complexed with metals, 1008, is conditioned, as required, to: effect the recovery of at least most of the CN- to a complexed state with metals, by adding 1010 Cu complexing with Cn- or another cyanide complexing metal, and adjusting 1020 the calcium content of the waste stream by conventional softening with Na2CO3 (soda ash), or preceding ion exchange metals to the 1040 nanofilter concentration of the cyanide component complexed with metals from the waste stream to 15 percent or less, by volume, of the "concentrated" stream of the 1050 nanofilter process. The concentrated stream of nanofilter 1050 carries at least most, if not all, of the metals and complexed cyanide associated with the incident waste stream over the membrane circuit. Depending on the metal content of the 1050 nanofilter concentrated stream, and other site-specific operating factors (eg, site availability of solar radiation to effect the oxidation of photocatalyzed CN with sol, and availability and cost of land) for pond solutions for solar exposure, the cost of H2S04 or H202 reagents on site, etc.), the concentrated cyanide-rich membrane solution complexed with 1050 metals can be introduced directly to photocatalyzed peroxidation, or can be further concentrated in the solar pond, before photocatalyzed peroxidation. Optionally, the CN content of the solution can be concentrated, and the CN species can be changed to CN ~, through the known process of acidification-volatilization-regeneration, preceding the oxidative destruction of CN- photocatalyzed on a bed of CNO . Continuing with the reference to Figure 10, the concentrate 1050 is contacted 1052 with an acid 1054, to lower the pH preferably to about a pH of 3 or less, more preferably about a pHL of 2, and the CN is removed by acidification-volatilization to form a current of about >; 68.9 grams / liter of CN for solar photolytic peroxidation 1062. In response to the reduction in pH, copper cyanide is precipitated from the solution. The copper cyanide is removed 560 from the acidified concentrate by solid / liquid separation techniques 1060, to produce a copper-cyanide solid 1064, to be recycled, and a copper-empty concentrate (ie, the liquid component) 1066. The copper concentrate 1066 is dispersed 1070 with a suitable gas 1072, such as air, to volatilize the cyanide gas from the concentrate 1066. The dispersed concentrate 1074 is contacted 1080 with OH-üT another suitable base, to raise the pH preferably to at least about a pH of 7. The cyanide-containing 1068-containing gas is contacted with an alkaline solution 1076, such as by scrubbing, to produce a solution containing cyanide 1082. The liquid contacted with the gas Release Cyanide 1068 is basic (ie, has a pH greater than about one-pH of 10), to cause the cyanide gas to enter the solution. The cyanide-containing solution is contacted 1084 with an oxidant, such as hydrogen peroxide, and then subjected to solar photolytic peroxidation 1062 to produce clean water for discharge. The discharge of solutions containing more than trace amounts of WAD CN (ie, CN loosely bound to, for example, Cu, Zn, and Ni), or free cyanide (CN "), either directly to the environment, or to Municipal water treatment systems (eg, sewage) are illegal.The WAD and free cyanide components of the solutions must be treated to "kill" cyanide (ie, to oxidize cyanide to cyanide) before These discharges are allowed There is a class of cyanide complexed with strongly bound metals called "strong acid dissociable", or WAD CN, which is permissibly discharged when the CN content of an incident waste stream on the membrane concentrator is .> 5 grams / liter (ie 500 ppm CN), the membrane concentrate will emit approximately 30 grams / liter of total CN.Cylanide concentrations of 30 grams / liter make better use of a peroxide reagent, H202, c When peroxide is added to the waste stream of CN, to adjust the H202 content of the waste stream to H202 0.88M (30 grams / liter), and the solution is solar, or otherwise exposed to ultraviolet light. the appropriate wavelength, than the solutions with less cyanide content. The lower concentrations of cyanide can be treated photocatalytically, but with a reduced economic benefit, because the H202 reagent is in excess, and can not be diluted (ie, the destruction of photocatalyzed peroxidative CN is a phenomenon related to the concentration of H202 in solution). It is not common to find industrial waste as strong as 5 grams / liter of CN, and the photocatalyzed peroxidative destruction of CN would commonly be used on solutions of lower concentration (with the benefit of savings in reduced H202 reagent previously observed), except that the solutions of lower concentration of CN can be further reinforced by the low-cost solar evaporation preceding the photocatalyzed peroxidation. Another option for the treatment of the solutions of lower concentration of CN, is the sulfurization-acidification-volatilization-regeneration (AVR) of the CN from the waste stream, to a stream of concentrated hydroxide (content of 70 grams / liter of CN-). The sulfurization process-AVR volatilizes the content of free and complexed cyanide from a waste stream, to recover as CN-, to a hydroxide treatment tower solution. If the CN- component of the recovered hydroxide solution is high (eg, 68 grams / liter or more of CN ~), the solution can be peroxidized photocatalytically in a completely beneficial way. CN- strong and weak solutions can also be oxidized with CN- photocatalytically by exposure to sunlight, or to other ultraviolet light of the appropriate wavelength on a bed of semiconductor particles, such as ZnO. The reagent uses required for photocatalyst destruction of CN by chemical means are reduced by an order of magnitude over the reagent uses required for the destruction of gross, non-concentrated waste cyanide streams. Although the concentration of the waste stream can be reduced by means other than the nanofilter membrane method, most notably by pond and solar evaporative concentration, the creation of large bodies of waste water loaded with CN on the outside represents a risk to local and migratory wildlife, and potentially, to humans. By concentrating the waste stream in nanofilter in such a way that 85 percent of the CN effluent is purged, and suitable for immediate disposal, the size, cost, and associated responsibility of pond concentration is substantially reduced. additional solar evaporation. If the sulfurization-AVR process is used, small volumes of concentrated CN-solution can be exposed daily to sunlight in the reaction trays, and the cost and responsibility of evaporation concentration in the pond is entirely eliminated. In still another embodiment, a non-precious metal recovery process includes the step of filtering an impregnated cyanide leach solution containing the non-precious metal, to form a concentrate containing most of the non-precious metal and a permeate. Normally, the cyanide leaching solution is generated during a precious metal recovery process. When the concentrate includes a non-precious first metal, such as copper, and a second base metal, such as zinc, iron, and nickel, the process may include the additional steps of first removing the second non-precious metal from the concentrate, and second, recover the first non-precious metal from the concentrate. Referring to Figure 11, in the heap or vat leaching 1110 of the non-precious metal-precious metal ores, the impregnated leaching solution 1114 is subjected to recovery of precious metals 1122 to form a precious metal product and a solution Waste 1130. Waste solution 1130 is passed through a nanofilter membrane or other suitable filtering device 1118, to form a retentate 1138 that contains at least most of the non-precious metals. The retentate 1138 preferably represents 1/4 or less, more preferably 1/10 of the waste liquor stream. The 3/4 of the leaching solution 1134 (more preferably 9/10 of the original waste volume), not contaminated by non-precious metals, can be reused without detrimental recovery effects - and precious metals leaching index. The sequestered volume of the non-precious metal waste 1132 can be processed for the recovery of its contents of cyanide and non-precious metals and precious metals, and discarded. In still another embodiment, a recovery process of base metal and precious metals includes the steps of: (a) solubilizing at least a portion of the non-precious metal and the precious metal, if present, in the feedstock, to form the impregnated leaching solution; (b) adsorb the precious metal and the non-precious metal in the leaching solution impregnated with carbon or resin; (c) converting the precious metal and non-precious metal adsorbed to an eluent stream of carbon or resin; (d) filtering the eluent stream of carbon or resin to form a permeate containing most of the precious metal, and a concentrate containing most of the non-precious metal; and (e) recovering, by electrolytic extraction, acid precipitation, or other means, the precious metal of the permeate, and the base metals of the concentrate. Referring to Figure 12, in the carbon adsorption 1240 and in the electrolytic extraction 1246, the non-precious metals, and especially copper, are carried to the carbon solution 1242. This solution 1242 is fed to an electrolytic extraction cell. 1246 for the veneering of precious metals. Copper and other non-precious metals contaminate the cathode product of the process, unless extraordinary electrolytic extraction techniques, such as pulse tower, are used. The higher the non-precious metal component in the elution solution, the higher the degree of cathode contamination. Contaminated cathodes require large doré furnaces and more energy to produce a high quality precious metal product. The nanofiltration 1218 of the eluate or of a purge stream 1250 of the circulating elution-catholyte solution 1242, can maintain the non-precious metal-copper content of the solution sufficiently low so that the non-precious metal contamination of the metal product Precious be minimal. The non-precious metal concentrate or retentate of nanofiltration 1254 would be swept by the precious metal, and then discarded. The permeate of the nanofilter purged with non-precious metal 1258 would be re-introduced into the circulating catholyte stream. The fresh catholyte 1262, of a volume equal to the purge of the circuit as the concentrate of nanofilter 1254, would be purged to the system to maintain the equilibrium of the solution. Although various embodiments of the present invention have been described in detail, it can be seen that those skilled in the art will think about modifications and adaptations of these modalities. However, it should be expressly understood that these modifications and adaptations are within the scope of the present invention, as stipulated in the following claims.

Claims

1. A process for the recovery of a precious metal from a mineral containing the precious metal, and a metal different from the precious metal, which comprises: contacting the mineral with a leaching solution containing cyanide, to form a liquid product containing a dissolved monovalent complex of precious metal-cyanide, and one or more multivalent complexes dissolved from metal-cyanide, and having a pH of about a pH of 9 to about a pH of 11; passing at least a portion of the liquid product through a nanofiltration membrane to form a retentate containing a portion of the dissolved monovalent precious metal-cyanide complex, and at least most of the one or more multivalent dissolved complexes of metal-cyanide , and a permeate containing at least most of the dissolved monovalent precious metal-cyanide complex; and subsequently recovering the precious metal in the dissolved monovalent precious metal-cyanide complex from the permeate to form a precious metal product.

2. The process of claim 1, wherein the nanofiltration membrane has an electrical charge to repel the one or more dissolved multivalent complexes of metal-cyanide, and pass the dissolved monovalent complex of precious metal-cyanide.

The process of claim 1, wherein the one or more metal-cyanide multivalent dissolved complexes include a multivalent copper-cyanide complex, and at least the majority of the copper in the liquid product is in the form of the multivalent complex of copper-cyanide.

The process of claim 1, wherein the precious metal in the precious metal-cyanide dissolved monovalent complex is selected from the group consisting of gold, silver, and mixtures thereof.

The process of claim 1, wherein the metal in the one or more dissolved multivalent metal-cyanide complexes is selected from the group consisting of copper, zinc, cobalt, iron, calcium, magnesium, nickel, lead , cadmium, mercury, platinum, palladium, and mixtures thereof.

The process of claim 1, wherein the retentate contains more than about 50 percent of the one or more dissolved multivalent complexes of metal-cyanide.

The process of claim 1, wherein the retentate contains less than about 50 percent of the dissolved monovalent precious metal-cyanide complex.

The process of claim 1, wherein the permeate contains at least about 50 percent of the dissolved monovalent precious metal-cyanide complex.

9. The process of claim 1, wherein, in the subsequent recovery step, at least a portion of the precious metal in the precious metal-cyanide monovalent complex is recovered by at least one of the following techniques: foundations, amalgamation, precipitation , ion exchange, electrolysis, absorption, and adsorption.

The process of claim 1, which further comprises recovering at least a portion of the metal in the one or more dissolved multivalent complexes of metal-cyanide from the retentate.

The process of claim 10, which further comprises recycling at least a portion of the cyanide in the retentate after the subsequent recovery step.

The process of claim 1, wherein the permeate includes water, and wherein the subsequent recovery step comprises passing at least a portion of the permeate through a second filter having a pore size smaller than the membrane of the permeate. nanofiltration, to form a second retentate that includes at least most of the dissolved monovalent precious metal-cyanide complex, and a second permeate that includes at least most of the water.

The process of claim 1, which further comprises: contacting at least a portion of the retentate with a chelating agent; remove the cyanide from the retentate to form a retentate drained of cyanide; recover at least a portion of the metal in the one or more dissolved multivalent complexes of metal-cyanide from the retentate emptying cyanide, to form a wasteful retentate; and passing at least a portion of the wasteful retentate through a filter to form a second retentate that includes at least most of the chelating agent in the waste stream, and a second permeate.

The process of claim 1, which further comprises: passing at least a portion of the retentate through an electrolytic extraction cell, to recover at least a portion of the metal in the one or more multivalent complexes dissolved from metal-cyanide , and form a voided retentate; and passing at least a portion of the retentate emptied through a second filter, to form a second retentate, to recycle to the previous pass step, and a second permeate. - 15.

The process of claim 14, which further comprises, before passing step: contacting at least a portion of the retentate with an acid to convert the cyanide to HCN; remove the HCN from the acidified retentate, to form a retentate emptied of cyanide; and contacting at least a portion of the retentate emptied of cyanide with a base, to form an electrolytic solution for the electrolytic extraction cell.

The process of claim 1, which further comprises: precipitating at least a portion of the metal in the one or more dissolved multivalent metal-cyanide complexes from the retentate as a metal cyanide compound; subsequently, dissolving the metal cyanide compound in an aqueous solution to form an electrolyte solution; and electrolytically extracting the metal from the electrolyte solution.

The process of claim 1, which further comprises: adsorbing at least a portion of the metal from one or more dissolved multivalent complexes of metal cyanide in the retentate on a substrate; Desorb the metal in an eluate solution; passing at least a portion of the eluate solution through a second filter, to form a second retentate that includes at least most of the copper, and a second permeate; and extract electrolytically from the second retentate.

18. The process of claim 1, further comprising: contacting a cyanide-containing effluent with light to convert the cyanide thereof to a cyanate.

The process of claim 18, further comprising: contacting the effluent with a metal to convert free cyanide from the effluent to a metal-complexed state.

20. A process for recovering a precious metal from a mineral containing the precious metal, and a metal other than the precious metal, which comprises: contacting the mineral with a leaching solution containing cyanide, to form a liquid product containing a dissolved monovalent complex of precious metal-cyanide, and one or more dissolved multivalent metal-cyanide complexes, recovering the precious metal from the dissolved monovalent precious metal-cyanide complex from the liquid product, to form a solution emptied of precious metal, and pass at least a portion of the solution drained of precious metal through a nanofilter, to form a retentate containing one or more dissolved multivalent complexes of metal cyanide, and a permeate

21. The process of claiming 20, where the recovery step includes: adsorbing the precious metal and small portions of the metal from the multivalent cyanide complex e metal, from the liquid product, on a substrate; Desorb the precious metal and metal to form an eluate solution that includes dissolved precious metal and dissolved metal; and electrolytically extracting the precious metal from the eluate solution.

22. The process of claim 20, which further comprises, after the step of passing: "first recovering a first multivalent metal dissolved from the retentate, to form a partially drained retentate; and second, recovering a second dissolved multivalent metal that is different from the first dissolved multivalent metal, from the drained retentate.

23. A process for recovering a precious metal from a feedstock containing the precious metal and a metal other than the precious metal, which comprises: contacting the feedstock-with a leaching solution to form a liquid product which contains a dissolved precious metal and a non-precious metal; adsorb the precious metal and the non-precious metal in the liquid product on carbon or a resin; converting the precious metal and non-precious metal adsorbed to an eluate stream; nanofilter at least a portion of the eluate stream, to form a permeate containing the majority of the precious metal, and a concentrate containing most of the non-precious metal; and recovering the precious metal from the permeate.

24. The process of claim 23, which further comprises recovering the non-precious metal from the concentrate.