Any metal having a low α-ray emission, the metal being any one of tin, silver, copper, zinc, or indium, wherein an emission of an α-ray after heating the metal at 100° C. in an atmosphere for six hours is 0.002 cph/cm.sup.2 or less. Any metal of tin, silver, copper, zinc and indium each including lead as an impurity is dissolved to prepare a hydrosulfate aqueous solution of the metal and lead sulfate is precipitated and removed in the solution. The lead sulfate is precipitated in the hydrosulfate aqueous solution by adding a lead nitrate aqueous solution including lead having an α-ray emission of 10 cph/cm.sup.2 or less to the hydrosulfate aqueous solution, from which the lead sulfate has been removed, and, at the same time, the solution is circulated while removing the lead sulfate to electrowinning the metal using the hydrosulfate aqueous solution as an electrolytic solution.

Methods for recovering a metal value from a metal-bearing material are provided. The method comprises agglomerating the metal-bearing material with an agglomeration solution comprising a raffinate, an oxidant, and citric acid or salts thereof to form an agglomerated metal-bearing material; leaching the agglomerated metal-bearing material with a leaching solution comprising the raffinate and the citric acid or salts thereof to produce a pregnant leaching solution and a leached material; re-oxidizing the leached material with a curing solution comprising the raffinate and the oxidant; and recovering the metal value from the pregnant leach solution to produce the raffinate.

An integrated pressure leaching, heap leaching process for recovering copper from sulphidic feed containing iron, arsenic, and copper. Aqueous feed slurry of the sulphidic feed is pressure oxidized to form a liquid phase containing free sulphuric acid and aqueous copper sulphate, and to precipitate arsenic as solid iron arsenic compounds. Treated slurry is withdrawn from the pressure vessel and the liquid phase is separated from the solids. Copper is recovered from the separated liquid phase and generates a solution enriched in acid and depleted in copper. At least a portion of this solution is neutralized in a copper heap leach to produce a PLS containing copper and reduced in acid. At least a portion of the heap leach PLS is neutralized to produce a solution further reduced in acid, and solids containing copper precipitates, followed by a liquid solid separation. The solution further reduced in acid is recycled as process solution for the pressure leach, while the solids containing copper precipitates are recycled to combine with either the treated slurry from the pressure leach, or the liquid phase from liquid solid separation, to re-dissolve copper and other metal values. The solids from the latter step are separated and the liquid phase is fed to copper recovery.

Method of biodesintegrating metal scrap with a bacterial consortium adapted to high concentrations of ferrous sulfate and ferric sulfate, access RGM 2972 of the Chilean Collection of Genetic and Microbial Resources; intermediate solution comprising it, useful in eliminating surface oxidation in metallic structure; and oxidizing solution, useful in the hydrometallurgical extraction of copper.

The invention discloses Method for whole component microwave fast digestion and precious metal extraction from ionic liquid of waste circuit board, and belongs to the field of hydrometallurgy. Based on the theory that microwaves can directly penetrate through a leaching medium to directly heat a circuit board, microwave-assisted leaching can reinforce mass transfer and heat transfer in the traditional leaching process, the leaching time is greatly shortened, and the leaching efficiency is improved. Before leaching, a waste circuit board does not need to be smashed, and environmental protection is achieved while energy is saved. The temperature rising process and reaction time of the reaction can be controlled, the whole process is conducted under the airtight condition, heat loss in the leaching process is avoided, the valuable leaching rate is high, the selectivity is high, and efficient leaching of valuable metal can be achieved. Precious metal leachate is extracted through imidazolium ionic liquid, the selectivity of the imidazolium ionic liquid to gold is high, and the co-extraction phenomenon of gold, nickel, copper and other ions is avoided. The method for extracting the precious metal leachate through ionic liquid is a green and clean recycling method, and the overall recycling rate of gold, nickel and copper can reach 99% or above.

A method for recycling lithium batteries containing the steps: (a) digesting comminuted material (10), which contains comminuted components of electrodes of lithium batteries, using concentrated sulphuric acid (12) at a digestion temperature (T.sub.A) of at least 100° C., in particular at least 140° C., so that waste gas (14) and a digestion material (16) are produced, (b) discharging the waste gas (14) and (c) wet chemical extraction of at least one metallic component of the digestion material (16).

A process for recovering copper from heap leach residues containing residual copper, includes identifying a production zone within the heap leach residues for secondary leaching, drilling wells into the heap at locations suitable for delivering leach solution into the production zone, injecting the leach solution including ferric ions through the wells and aerating the production zone to facilitate oxidative reactions within the production zone, and collecting effluent from the heap for copper recovery therefrom.

A method of improving leach kinetics and recovery during atmospheric or above-atmospheric leaching of a metal sulfide is disclosed. A system for practicing the aforementioned method is also disclosed. Apparatus for practicing the aforementioned method is also disclosed. A new composition of matter which is formed by the aforementioned method, and which may be utilized in the system and apparatus is further disclosed. The new composition of matter may exhibit improved leach kinetics, and may have some utility in the semi-conductor arts, including uses within photovoltaic materials.

A method of leaching copper from a heap of ore which includes an ore agglomeration step, an ore stacking step wherein agglomerated ore is stacked to form a heap, a curing step, a leach step, and a rinse step, wherein, during the ore agglomeration step the ore is contacted with an acidified solution, nitrates or nitrites, and chloride, to create an oxidative environment prior to the leach step.

A method of improving metal leach kinetics and recovery during atmospheric or substantially atmospheric leaching of a metal sulfide is disclosed. In some embodiments, the method may comprise the step of processing a metal sulfide concentrate in a reductive activation circuit 220 that operates at a first redox potential, to produce a reductively-activated metal sulfide concentrate. The method may further comprise the step of subsequently processing the activated metal sulfide concentrate in an oxidative leach circuit 240 to extract metal values. In some disclosed embodiments, reductive activation steps and/or oxidative dissolution steps may employ mechano-chemical and/or physico-chemical processing of particles or agglomerates thereof. Reductive activation may be made prior to heap leaching or bio-leaching operations to improve metal extraction. Systems for practicing the aforementioned methods are also disclosed.