“Zoloto Severnogo Urala” Close Company

A. V. Novikov, Managing Director
G. L. Maksimov, Head of Central Laboratory

“Polymetal Engineering” Close Company
A. A. Fateev, Engineer
B. M. Milman, Head of Laboratory of Solutions Reprocessing
N. V. Vorobev-Desyatovskiy, Head of Hydrometallurgy Department, e-mail: Vdesjatovsky@polymetal.spb.ru

Activated carbons, saturated by cyanide complexes of gold (I) and silver (I), nonferrous metals, iron and containing insoluble compounds of calcium have been investigated. It was established that acid washing of carbons implemented before desorption of precious metal with solution of NaOH at 150 ^oС results in reducing calcium impurities from the absorbent surface but has a negative effect on desorption of gold (I) and especially silver (I). Addition of NaCN to the eluting solution slightly improves the extraction of precious metal from the activated carbons, but it is accompanied by an effective decay of NaCN under severe conditions of desorption of gold (I) and losses of silver (I). Acidic washing of carbon after the elution of gold (I) from carbon is preferable, but doesn’t solve the problem of desorption of silver (I) compounds. It shown that the disposal of acidic washing (before or after desorption) has little effect to remove the iron, nickel and zinc compounds from charcoal, and cyanide complexes of these metals in the individual state are characterized by a low sorption affinity to activated carbons. Some assumptions about the causes of their ill-eluting are made and ways to reduce the negative impact of these impurities on hydrometallurgical processes are suggested.

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