Compositions and methods are provided that provide recovery of metals such as copper, nickel, cobalt, indium, and other metals are recovered from mine tailings, in situ ore bodies, or postconsumer waste. An amine-containing lixiviant is utilized to generate an aqueous solution of the desired metal from insoluble salts present in the source material. Metals can be recovered and further purified by various processes, including extraction into an immiscible organic solvent, electrowinning, crystallization, and chemical reduction. Spent lixiviant can be regenerated and recycled back into the metal recovery process.

A vertical low-pressure reactor with stirred tank for leaching polymetal minerals and concentrates of lead, copper, zinc, iron and/or the mixtures thereof, in a solid-gas-liquid three-phase suspension system. The low-pressure vertical reactor with stirred tank consists of: a cylindrical vertical container with three or four deflectors evenly distributed across the 360; a stirring system made up of two impellers coupled to a rotary shaft, that provides adequate reaction and interaction of the metal species of interest; a space of the volume of the reactor, corresponding to 20% to 35% of the total volume of the container, located at the top of the reactor and which acts as a gas chamber that provides a continuous feed of oxygen; and a system of coils placed on the outside or inside surface of the reactor to ensure efficient heat-transfer reactions and controlled kinetics.

The invention refers to a method for recovering copper from waste fishing nets. The method of the invention includes washing of nets in a washing liquid, wherein an antifouling coating and other impurities are removed from the surface of the nets to a largest extent possible. The washing liquid is water; NaOH can also be added into the water in order to improve the efficiency of washing, such that the NaOH concentration in the water is up to 20%. The suspension of the washing liquid, sludge and other impurities, resulting from the washing step, is led to a separation step. The sludge obtained in the separation step is led to the dissolution step in an acidic medium. A strong mineral acid is selected as the acidic medium, such as H.sub.2SO.sub.4, HNO.sub.3, HCl, a mixture of strong mineral acids or a mixture of one or several strong mineral acids with H.sub.2O.sub.2. Then, the non-dissolved sludge is separated from the solution of copper ions Cu.sup.2+ in the acidic medium, the solution of copper ions Cu.sup.2+ in the acidic medium is led to electrolysis, wherein elementary copper having a purity of more than 94% is deposited on the cathode. The non-dissolved residual sludge can be optionally led to thermal treatment to the reactor, where the residual paraffins and co-polymers are removed at a temperature ranging from 500 C. to 900 C. The remaining ash may contain up to 30% by weight of copper compounds based on the weight of the ash, particularly in the form of copper(ll) oxide CuO, less in the form of copper(l) oxide Cu.sub.2O and copper phosphates Cu(H.sub.2PO.sub.4).sub.2, Na.sub.6Cu.sub.9(PO.sub.4).sub.8. This ash is then led to dissolution in the acidic medium and to further steps of the method. The proposed method of the invention improves the method for recycling waste nets, such that not only pure polyamide is obtained from the nets but also elementary copper, which has a double benefit: elementary copper in a sufficiently pure form is a useful raw material, moreover, the quantity of copper in final waste is reduced, consequently a negative impact on the environment is reduced and the cost of waste disposal of the method is reduced as well.

A method of controlling iron in a hydrometallurgical process is disclosed. The method may comprise the steps of: leaching (14, 114) a feed slurry (2, 102); forming a pregnant leach solution (12a, 12b; 112a, 112b); removing a first leach residue (18, 118) from the pregnant leach solution (12a, 12b); and sending a portion (12b, 112b) of the pregnant leach solution (12a, 12b) and/or raffinate (22, 122) produced therefrom, to an iron removal process (34, 134). According to some preferred embodiments, the iron removal process (34, 134) may comprise the steps of: sequentially processing the pregnant leach solution (12a, 12b) and/or raffinate (22, 122) produced therefrom in a first reactor (R.sub.1) a second reactor (R.sub.2), and a third reactor (R.sub.3); maintaining a pH level of the first reactor (R.sub.1) above 4, by virtue of the addition of a first base; maintaining a pH level of the second (R.sub.2) and/or third (R.sub.3) reactors above 8.5, by virtue of a second base; and forming solids (46) comprising magnetite (68). The method may further comprise the steps of performing a solid liquid separation step (36) after the iron removal process (34, 134); and performing a magnetic separation step (64) to remove magnetite (68) from said solids comprising magnetite (68), without limitation. A system for performing the method is also disclosed.

A process for recovery of one or more elements, selected from precious metals and chalcophile metals, as herein defined, from materials containing precious and/or chalcophile metal/s, said process including: (i) contacting the material with an alkaline solution containing a lixiviant comprising an amino acid, or derivative thereof, and an alkali stable transition metal complex in order to form a leachate containing the precious metal and/or chalcophile metal; and (ii) recovering the precious metal and/or chalcophile metal from the leachate.

A method of selectively leaching a metal such as nickel from an ore or ore processing intermediate comprising the metal and cobalt. The ore or ore processing intermediate is contacted with an acidic leach solution comprising an amount of an oxidising agent sufficient to oxidise a major portion of the cobalt to thereby cause it to be stabilised in the solid phase while a major portion of the metal is dissolved for subsequent recovery.

A method of leaching copper-containing ores includes leaching copper-containing ores or concentrates or tailings of the ores or concentrates with a leach liquor in the presence of an additive that enhances the dissolution of copper from copper minerals in the ores and concentrates by forming a complex between (a) sulfur, that has originated from copper minerals in the ores, and (b) the additive. A method of leaching copper-containing ores includes leaching copper-containing ores or concentrates or tailings of the ores or concentrates with a leach liquor includes leaching copper-containing ores or concentrates or tailings of the ores or concentrates with a leach liquor in the presence of a nitrogen-containing organic complexing additive that forms a complex between sulfur, that has originated from copper minerals in the ores, and the additive.

A method of leaching copper-containing ores, such as chalcopyrite ores, with a leach liquor in the presence of silver and an activation agent that activates silver whereby the silver enhances copper extraction from copper ores.

A system and method for improving leach kinetics and recovery during above-atmospheric leaching of a metal sulfide is disclosed. In some embodiments, the method may comprise the steps of: (a) producing a metal sulfide concentrate [34] via flotation; (b) moving the produced metal sulfide concentrate [34] to at least one chamber [22a] of at least one reactor such as an autoclave [20]; (c) leaching the produced metal sulfide concentrate in said at least one chamber [22a] in the presence of oxygen [82] at a pressure and/or temperature above ambient, and in the presence of partially-used [25] and/or or new [92] grinding media within the at least one chamber [22a]. Systems [10] and apparatus [20, 200] for practicing the aforementioned method are also disclosed.

A method of leaching chalcopyrite ores includes the steps of forming agglomerates of fragments of chalcopyrite ores and silver and leaching the agglomerates with suitable leach liquor.