Silver leaching from a mechanochemically pretreated complex sulfide concentrate

The intensification of thiourea leaching of silver from a silver-bearing complex sulfide concentrate (Casapalca, Peru) using mechanochemical alkaline leaching as the pretreatment step was investigated. The leaching of "as-received" concentrate in an acid thiourea solution resulted in 5% Ag dissolution. After pretreatment, 90% of the silver was leached within 10 min. The mechanochemical pretreatment resulted in up to 78% of tetrahedrite degrading and an increase in the specific surface area of the concentrate from 0.3 to a maximum of 15.7 m(2) g(-1). The pretreatment was performed in an attritor using variable milling times and sample weights. The physicochemical changes in the concentrate as a consequence of mechanochemical pretreatment had a pronounced influence on the subsequent silver extraction. (C) 2003 Elsevier Science B.V. All rights reserved.