What is cyanide leaching ? Give an example.

Explanation

(i) The crushed ore of gold is leached with aerated dilute solution of sodium cyanide.
(ii) Gold is converted into a soluble cyanide complex.
(iii) The gangue, aluminosilicate remains insoluble.
`4Au_((s)) + 8CN_((aq))^(-) + O_(2(g)) + 2H_(2)O_((l)) rarr 4[Au(CN)_(2)]_((aq))^(-) + 4OH_((aq))^(-)`