Slurry electrowinning process
AssigneeEnvirotech Corporation
InventorsRobert C. Emmett, Jr., James K. Dicksa, Bruce C. Wojcik, Frank A. Baczek
Life of this patent
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Abstract
Apparatus and process for continuous electrowinning of copper bearing slurries, including an electrowinning cell wherein a slurry composed of a suitable electrolyte and a copper-bearing solid material, is subjected to the simultaneous reactions of dissolving the copper material and plating out elemental copper as a relatively pure copper product. The apparatus and process also includes means to purify the copper-bearing material before passage to the electrowinning cell so as to prevent contamination of the electrolyte in the cell and, also, a means to recover sulfur which is released during the electrowinning and unreacted copper material.
Claims30
A method of leaching an aqueous slurry of copper-bearing solids to remove non-copper metal ions in order to produce a suitable feed of solids for an electrowinning cell which comprises the steps of:
- a. leaching said copper-bearing solids with a moderately strong aqueous acid to solubilize metal ions into solution in the aqueous acid;
- b. then adding calcium sulfite to the aqueous acid solution to reduce the copper ion concentration by forming copper-precipitate solids therein;
- c. then separating the copper-precipitate solids and any remaining portions of said copper-bearing solids from the aqueous acid solution, thereby to form a first stream comprising clear liquid and a second stream comprising a slurry containing said copper-precipitate solids and remaining portion of said copper-bearing solids.
A method of electrowinning a slurry of copper-bearing solids to produce a copper plate of high purity which comprises the steps of:
- a. introducing to a zone between electrodes including a cathode and an anode said copper-bearing solids in a slurry with electrolyte with said solids in suspension in said electrolyte, wherein said electrolyte has a sulfuric acid concentration in the range of about 70-150 grams/liter, a ferrous ion concentration of about 15-35 grams/liter, a ferric ion concentration of about 1-8 grams/liter with a ratio of ferrous to ferric of about 15-1 to 31/2-1 and a ratio of copper ion to total ferrous and ferric ions in the range of about 3-1 to 0.6-1.
- b. applying an electrical potential to said electrodes to induce a high current flow.
The method of clain 22 wherein the slurry between said cathodes and said anodes is agitated with bubbling gas.
A method of preleaching an aqueous slurry of copper-bearing solids to remove non-copper metal ions and electrowinning thereafter which comprises the steps of:
- a. leaching said copper-bearing solids with a moderately strong aqueous acid to solubilize metal ions into solution in the aqueous acid;
- b. then adding calcium sulfite to the aqueous acid solution to reduce the copper ion concentration by forming copper-precipitate solids therein;
- c. then separating the copper-precipitate solids and and remaining portions of said copper-bearing solids from the aqueous acid solution, thereby to form a first stream comprising clear liquid and a second stream comprising a slurry containing said copper-precipitate solids and remaining portion of said copper-bearing solids.
- d. introducing to a zone between electrodes including a cathode and an anode said copper-bearing solids in a slurry with electrolyte with said solids in suspension in said electrolyte, wherein said electrolyte is a strong acid and includes ferrous ion and ferric ion;
- and
- e. applying an electrical potential to said electrodes to induce a high current flow.
A method for recovering copper and sulfur values from solids separated from a slurry discharged from an electrowinning method in order that said copper values can be returned to the electrowinning method and said sulfur is available for generating sulfur acids comprising the steps of:
- a. slurrying said separated solids in aqueous solution;
- b. adding copper and sulfur collector reagents and frother agents;
- c. then separating said slurry between a first stream comprising floated copper and sulfur and solution and a second stream comprising a slurry containing the remaining solids;
- d. then separating said copper and sulfur from the solution, thereby to form a third stream of solution, and a first cake containing said copper and said sulfur;
- e. reacting said first cake in a slurry with ammonia gas and hydrogen sulfide gas to form soluble ammonium polysulfides;
- f. then separating the remaining copper solids from the solution containing ammonium polysulfides thereby to form a fourth stream comprising clear liquid containing ammonium polysulfides and a second cake containing said remaining copper solids;
- g. evaporating said fourth stream to generate ammonia gas, hydrogen sulfide gas and a slurry containing elemental sulfur.
Dependencies are inferred from the claim text.