METHOD OF CLEANING OF SILVER-BEARING MATERIAL Russian patent published in 2014 - IPC C22B11/00 C22B3/06 C22B3/44 C22B7/00 

FIELD: process engineering.

SUBSTANCE: invention relates to cleaning of silver-bearing materials by hydrometallurgy processes, for example, scrap and wastes of microelectronics. Proposed method comprises dilution of silver-bearing material in nitric acid, addition of sodium nitrate to nitrate solution at mixing, extraction of silver salt precipitate and pits treatment to get metal silver. Note here that after addition of sodium nitrate the reaction mix is held for 1 hour to add sodium carbonate or bicarbonate to pulp pH of 8-10. Free silver salt precipitate as silver carbonate is separated from the solution by filtration. Sodium nitrite and carbonate or bicarbonate is added in the dry form. Note here that sodium nitrite is taken with 25% excess of stoichiometry.

EFFECT: higher purity and yield, simplified process.

2 cl, 2 ex