Patent ID: 6919030

Claim:
A process for recovering cyanide from feed material containing cyanide and copper comprising the steps of: (a) contacting said feed material with a strong base anion exchange resin whereby copper and cyanide from said feed material are adsorbed onto said resin; (b) contacting the resulting resin with an eluant solution containing free cyanide ion to elute copper and cyanide from said resin, the amount of copper removed being approximately equivalent to the amount of copper adsorbed onto said resin in step (a); (c) separating the eluted resin from the eluting solution or eluate from step (b); (d) acidifying the eluate from step (b) to precipitate copper; (e) separating the acidified solution from the precipitate in step (d) and alkalizing directly or after concentration the separated solution containing HCN; (f) contacting the eluted resin from step (b) with an acid to condition the resin and remove additional cyanide while leaving most of the copper in the resin phase; (g) converting the HCN solution formed in step (f) to cyanide ion, directly or after concentration of the HCN solution, by the addition of alkali; and (h) returning the conditioned resin from step (f) to step (a) above.