Process for the recovery of gold and silver from used refractory bricks

A process for the recovery of gold and silver from the used refractory brick of the Dore furnace which comprises.

• (i) grinding used refractory bricks of the Dore furnace generated during the processing of the anode slimes of copper industry or from gold production plants to 80% to 200 mesh size
• (ii) roasting the ground refractory brick powder along with sodium chloride as an additive at a temperature in the range of 400-900° C.
• (iii) leaching the said roasted powder with ammoniacal sodium thiosulphate solution at a temperature in the range of 40-90° C. for 4-10 hrs and separating the solids and liquid by filtration
• (iv) precipitating silver from the leached liquor obtained from step (iii) as silver sulphide and converting it to metallic silver by heating at a temperature in the range 600-800° C.
• (v) leaching the solid residue obtained from step (iii with ammonium sulphate solution at a temperature in the range of 40-90° C. for 4-10 hrs to remove the acid consuming gangue constituents and filtering the solution
• (vi) leaching the solid residue obtaining from (v) with acidic thiourea solution in presence of ferric sulphate at a pH of 1 to 2.5 in the temperature range of 20-50° C. for 2-6 hrs and filtering
• (vii) mixing activated charcoal with the filtered leach liquor obtained from step (vi) and agitating for 1-2 hrs for adsorbing the gold onto the activated charcoal
• (viii) filtering the activated charcoal loaded with gold and incinerating it at a temperature of 700-800° C., for 2-3 hrs
• (ix) smelting the incinerated charcoal along with the metallic silver obtained from step (iv) to get gold-silver bullion and
• (x) parting gold and silver from the gold-silver bullion.