Recovery of gold from computer circuit board scraps: the study of the effect of different reductants

Computer circuit boards (ccbs) are valuable because of their precious metal contents. in this regard, the recovery of gold from ccbs has attracted great interest. in this work, we report the recovery of gold from ccbs with different reductants. the ccbs were first crushed mechanically to obtain particles with sizes less than 0.1 mm. the powders were then leached with nitric acid to remove undesired metals. the remaining was then treated with aqua regia to dissolve gold ion. the dissolved gold was then precipitated from the leachate with hydrazine, ferrous sulfate or oxalic acid and the effect of these reductants on the recovery of gold was studied. we were able to recover more than 99% of gold from ccbs with purity of about 99.5%.