The present application relates to methods for leaching and extraction of precious metals. For example, the present application relates to methods of leaching gold, palladium and/or platinum from a substance comprising gold, palladium and/or platinum (such as a gold-containing ore or a platinum group metal (PGM) concentrate) using an organic solvent that is water-miscible or partially water-miscible.

A method of separating a metal from a solution comprises adding to the solution a compound having a structure represented by Formula (I): wherein: R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently a substituted or unsubstituted aryl group or a substituted or unsubstituted C1-C8 hydrocarbyl group: and Z is a C2-C6 hydrocarbyl group or an aryl group.

Methods and compositions are described in which amine-based compounds are utilized in the recovery of rare earth elements from solution. The rare earth elements are recovered selectively and sequentially.

Hydrometallurgical compositions are described in which organic amine-based lixiviants and organic amine-based pre-lixiviants are utilized in the selective recovery of rare earth elements. The lixiviant species can be regenerated in situ, permitting the organic amine to be used in substoichiometric amounts.

Described herein are methods of recovering silver from solution to produce metallic (i.e., elemental) silver. These methods generally include a step of providing a silver-containing aqueous solution that includes cationic silver species, followed by a step of forming a reaction solution that includes an organic acid, a buffering agent, and the cationic silver species, and a step of generating a reaction product that includes metallic silver by reducing the concentration of the cationic silver species in the reaction solution. Also described herein are metallic or elemental silver produced by these methods.

The agent for selective metal recovery of the present invention includes a material derived from an alga belonging to the order Cyanidiales, which is dead cells or a cell surface layer of an alga belonging to the order Cyanidiales, or an artificial material produced by simulating the cell surface layer, or includes a porphyrin. The metal recovery method of the present invention includes an addition step of adding a material derived from an alga belonging to the order Cyanidiales, which is dead cells or a cell surface layer of an alga belonging to the order Cyanidiales, or an artificial material produced by simulating the cell surface layer, or adding a porphyrin, to a metal solution; and a recovery step of recovering a metal from the metal solution by the material derived from an alga belonging to the order Cyanidiales or the porphyrin.

The present disclosure provides an agent for selective metal recovery, a metal recovery method, and a metal elution method.