The invention relates to a method for recovering precious metals from electronic waste utilising biometallurgical techniques. In one aspect, a method of recovering one or more target metals from electronic waste, includes (a) removing at least a portion of non-target material from the electronic waste or grinding to a preselected size particle to give pre-processed electronic waste; (b) contacting the pre-processed electronic waste with a lixiviant such that at least a portion of the target metal(s) dissolve into the lixiviant to produce a pregnant solution; (c) contacting a microorganism with the pregnant solution such that at least a portion of the target metal(s) ions biosorb to the microorganism wherein the microorganism becomes metal laden and the pregnant solution becomes barren; (d) substantially separating the metal laden microorganism from the barren solution; and (e) recovery of the target metal(s) from the metal laden microorganism.

Alkaline oxidation process for treating refractory sulfide ore or concentrate particles enriched in a metal to be recovered comprising stages in which refractory ore or concentrate particles are surface-oxidized in an alkaline oxidation step in alkaline liquid phase with calcium hydroxide forming an alkaline slurry, which slurry is thereafter mechanically activated to remove passivating coatings from the surface oxidized refractory ore particles.

The present invention relates to a method for recovering metals using an adsorbent, which comprises preparing a leachate comprising metal ions and cyanides, wherein the metal ions comprise gold ions and copper ions; and in a state where the leachate has a cyanide (CN) concentration of 0.1 ppm or greater, adding to the leachate an adsorbent, which has an open circuit potential value between the open circuit potential value of the gold ions and that of the copper ions; and selectively adsorbing the copper ions to the adsorbent.

The present invention relates to a method for recovering metals using an adsorbent, which comprises preparing a leachate comprising metal ions and cyanides, wherein the metal ions comprise gold ions and copper ions; and in a state where the leachate has a cyanide (CN) concentration of 0.1 ppm or greater, adding to the leachate an adsorbent, which has an open circuit potential value between the open circuit potential value of the gold ions and that of the copper ions; and selectively adsorbing the copper ions to the adsorbent.

A method for precious metal extraction comprises contacting a precious metal-containing ore with an improved cyanide extraction agent under conditions suitable for the formation of a coated precious metal-containing ore where the extraction agent comprises (i) a cement and (ii) a cement retarder; and contacting the coated precious metal-containing ore with a cyanide solution to form soluble precious metal complexes. A composition for gold extraction comprising: (i) a cement (ii) a cement retarder and (iii) an inorganic cyanide salt.

A method for precious metal extraction comprises contacting a precious metal-containing ore with an improved cyanide extraction agent under conditions suitable for the formation of a coated precious metal-containing ore where the extraction agent comprises (i) a cement and (ii) a cement retarder; and contacting the coated precious metal-containing ore with a cyanide solution to form soluble precious metal complexes. A composition for gold extraction comprising: (i) a cement (ii) a cement retarder and (iii) an inorganic cyanide salt.

A process for the recovery of gold from carbon fines waste, which are produced, especially from carbon-in-leach (CIL) and carbon-in-pulp (CIP) processes. The gold may be eluted from carbon fines with alkaline eluent having a low oxidation reduction potential (ORP). Value added products may be obtained from the extracted carbon fines.

The present invention is intended for effectively removing copper, iron, sulfur, which are impurities, from activated carbon on which gold is adsorbed before gold eluting in the point of view of gold recovery, and is related to a method for eluting gold from an activated carbon on which at least sulfur (S) and gold (Au) are adsorbed, whereas the activated carbon is washed with an alkali solution before eluting the gold, and then the gold is eluted from the activated carbon.

The present invention is intended for effectively removing copper, iron, sulfur, which are impurities, from activated carbon on which gold is adsorbed before gold eluting in the point of view of gold recovery, and is related to a method for eluting gold from an activated carbon on which at least sulfur (S) and gold (Au) are adsorbed, whereas the activated carbon is washed with an alkali solution before eluting the gold, and then the gold is eluted from the activated carbon.

Methods for recovering gold from a refractory gold ore and concentrate are described. The method can include leaching the refractory gold ore and concentrate with the alkaline reagent under ambient or near-ambient conditions and a subsequent gold complexation. The method can optionally include separating a gold-containing leachate from a gold-unlocked solid residue obtained during the leaching step and performing a subsequent complexation on the gold-unlocked solid residue and optionally gold complexation on the gold-containing leachate. These methods can increase the gold recovery compared to conventional methods.