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Selective Recovery of Base Metals and Precious Metals from Ores.
U S Patent Number 4 423 011 1983 Dec; :
Sulfide ores containing precious metals are smelted into a matte with >95% recovery of the metals. The powdered matte is leached in 2 stages for selective metal recovery: (1) separation of fe and ni with 10-40% h2so4 at 40 deg - 100 deg c; and (2) leaching of copper at 50 deg - 100 deg c by h2so4 or hcl solutions containing fe3+ or cu2+ salts for the selective oxidation of the djurlite (cu1.93S) phase. The residue contains precious metals, elemental s, and pbso4. Optionally, the leaching of pyritic ores low in cu and ni is combined for the dissolution of fe and ni with removal of h2s, followed by addition of fe3+ or cu2+ salts. Thus, a sulfide flotation concentrate was smelted with cao, caf2, and sio2 and the matte product was separated from the slag. The matte (containing fe 53, ni 10.5, Cu 7.5, and s 31.5%, With pd 41.47, Pt 15.5, and au 2.66 Oz/ton) was powdered to -200 mesh in a ball mill. The 1st- stage leach was done for 4 h at 95 deg - 100 deg c with 2.06M h2so4 to recover >99% of the ni and fe. The residue (containing cu 66, ni 1, and fe 1%, with precious metals) was leached 6 h at 70 deg c in 0.15M h2so4 600 ml containing 19.6 G fe2(so4)3, dissolved >98% of the cu. The residue solids contained pd 1,640, pt 617, au 102 oz/ton, cu 1.7, Ni 0.32, and fe 0.06%. Similar results in the 2nd- stage leach were obtained with hcl solutions containing cucl2 and nacl.
U.S. Patent Number 4,423,011 December 27, 1983