Production of electrolytic copper from dilute solutions contaminated by other metals
AssigneeEcochem Aktiengesellschaft
InventorGianni Zoppi
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Abstract
The copper is selectively precipitated in the form of a sulfide from the solutions containing it, according to the reaction: Cu.sup.2+ +S.sup.2- .fwdarw.CuS The precipitated solid, constituted by copper sulfide, is filtered, washed and then leached with a solution of ferric fluoborate and fluoboric acid, which dissolves the copper as a fluoborate while forming elemental sulfur, according to the reaction: CuS+2Fe(BF.sub.4).sub.3 .fwdarw.Cu(BF.sub.4).sub.2+2Fe(BF.sub.4).sub.2 +S.sup.o After filtering off the sulfur, the copper fluoborate solution is subjected to an electrolysis in a diaphragm cell, obtaining a deposit of pure copper at the cathode and a regenerated solution of ferric fluoborate at the anode, which is utilized to leach further copper sulfide.
Claims5
A process for producing electrolytic copper from a dilute solution containing the same in an oxidized Cu.sup.2+ form contaminated by other metals, which comprises:
- a) reacting said Cu.sup.2+ solution with a reagent, comprising H.sub.2 S, Na.sub.2 S, NaSH, CaS, Ca(SH).sub.2, BaS, alkali thiosulfates, alkaline earth thiosulfates, thiourea, or thioacetamide, or a mixture thereof, thereby precipitating CuS, and separating said CuS by filtration;
- b) leaching said CuS with a solution of ferric fluoroborate and fluoroboric acid, according to the reaction:
- CuS+2Fe(BF.sub.4).sub.3 .fwdarw.Cu(BF.sub.4).sub.2 +2Fe(BF.sub.4).sub.2 +S.sup.0 ( 1)
- and separating the elemental sulfur thus produced by filtration;
- and
- c) subjecting the copper fluoroborate and ferrous fluoroborate solution obtained in step b) to cell-diaphragm electrolysis, in accordance with the following reactions:
- at the cathode:
- Cu(BF.sub.4).sub.2 +2Fe(BF.sub.4).sub.2 +2e.sup.- .fwdarw.Cu+2Fe(BF.sub.4).sub.2 +2(BF.sub.4).sup.- ( 2)
- at the anode:
- Cu(BF.sub.4).sub.2 +2Fe(BF.sub.4).sub.2 +2(BF.sub.4).sup.-2 -e.sup.- .fwdarw.Cu(BF.sub.4).sub.2 +2Fe(BF.sub.4).sub.3 ( 3)
- overall reaction:
- Cu(BF.sub.4).sub.2 +2Fe(BF.sub.4).sub.2 .fwdarw.Cu+2Fe(BF.sub.4).sub.3( 4)
- thereby producing electrolytic copper at the cathode.
Dependencies are inferred from the claim text.