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SELECTIVE AUTOCLAVE RECOVERY OF COPPER AND SILVER FROM WAELZ CLINKER IN AMMONIA MEDIUM

Upon processing of zinc ferrite cakes in Waelz kilns a waste product, called Waelz clinker, is obtained. The copper and silver contents in this product are comparable to those of their ores which turns it into a valuable raw material. In the present work the experimental results on selective autoclave leaching of Waelz clinker in ammonia medium are presented. The effect of main technological parameters on the degree of value metals recovery and iron precipitation is studied. It is established that the highest extend of copper and silver recovery is obtained under the following conditions: temperature 383 K, Po2 0.4 MPa, ammonia concentration 110 g l -1, ammonium sulfate concentration 70 g l-1, pulp density 100 g l-1and test duration 120 min. At these conditions 86,5 % of copper and 68,5 % of silver are solubilized, whereupon over 99 % of iron is hydrolytically precipitated. The composition of the corresponding leach solution is: 1,22 g l-1Cu, 10 mg l-1 Ag, 90 mg l-1 Zn, 30 mg l-1 Fe and 40 mg l-1 Mn.