Copper values are efficiently recovered from a copper ore, including secondary sulfides, by first crushing the ore to a particle size P-80 of about 1 to 2 inches, then grinding the so crushed ore to a particle size P-80 of between Tyler 4 mesh and 20 mesh, and then classifying the ground ore into a fines fraction of less than 65 mesh and one or more coarse fractions of more than 65 mesh. The fines are then leached or subjected to flotation to form a concentrate which is leached to form a pregnant leach solution. In parallel, the coarse fraction or fractions are leached also to form a pregnant leach solution. The leaching operations are carried out with ferric sulfate lixiviant at atmospheric pressure and elevated temperature. During leaching ferric sulfate is reduced to ferrous sulfate. The pregnant leach solutions are then subjected to solvent extraction to recover the copper values and subsequently to electrowinning to produce copper metal. During the solvent extraction operation, free sulfuric acid is produced and is then used together with oxygen to oxidize the ferrous sulfate produced during the leaching steps back to ferric sulfate with is then re-used in the leaching of the fines and coarse fractions.

A procedure to agglutinate ore concentrations, which can be of copper, on a gravel heap, to be leached on a non-flooded bed which comprises: artificially adhering the concentrate to the surface of a solid material base, which can be an artificial material, or a stony substance; the agglutinated material is stockpiled, forming a leaching pile; and is irrigated with a leaching solution containing at least Cl, Cu, and Fe ions.

A process is provided for heap leaching ore to recover nickel. The process is particularly effective for ores that have a tangible clay component (i.e., greater than about 10% by weight). The process includes sizing the ore (where necessary), forming pellets by contacting ore with a lixiviant and agglomerating. The pellets are formed into a heap and leached with sulfuric acid to extract the metal values, including nickel. The leachate may be subjected to a nickel recovery operation without the need for intermediate neutralization.

An improved method and apparatus is provided for the production of copper using a solvent extraction electrowinning process. Process streams formed during the process containing entrained liquids are fed to a cyclone to remove either organic extractant or water (aqueous solutions) from the stream. A raffinate stream fed to a cyclone removes entrained organic phase which organic phase may be recycled to the process. The separated raffinate stream would then typically be recycled to the copper ore leach step to form a pregnant leach solution without the loss of organic solvent and/or the environmental concerns associated with entrained solvent. In a preferred new process, mixers, preferably inline, are used in conjunction with cyclones to provide a solvent extraction electrowinning process which is continuous and efficient and the use of conventional mixers, and particularly settlers, are eliminated.

A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, producing a concentrate of refractory sulfide minerals from the separated fines and adding the concentrate to the heap, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometallurgically treating the bioleached ore to recover precious metal values contained therein.