Method of recovering metals from industrial by-products
AssigneeDowa Mining Co., Ltd.
InventorsHideki Abe, Hiroshi Tanaka
Life of this patent
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Abstract
There is disclosed a novel method of recovering valuable metals from an industrial by-product containing copper and arsenic and at least one metal selected from among lead, zinc, iron, silver and cadmium, said method comprising leaching the by-product with sulfuric acid in an SO.sub.2 gas atmosphere at a temperature of 70.degree. C. or higher in the presence of a solid sulfide to thereby precipitate copper selectively as copper sulfide while dissolving other metal or metals in the leach solution and then separating the copper containing precipitate from the leach solution, said leach solution containing substantially no copper.
Claims19
A method of recovering valuable metals from an industrial by-product that contains copper and arsenic, and at least one metal selected from the group consisting of lead, zinc, iron, silver and cadmium, at least part of said copper being present as acid-soluble copper in the form of at least one of oxides and sulfate, said method comprising the steps of:
- (1) leaching the by-product with sulfuric acid in an SO.sub.2 gas atmosphere at a temperature of at least 70.degree. C. in the presence of a solid sulfide or sulfur in an amount sufficient to precipitate all dissolved copper so as to maintain the solution substantially free of copper ions and to thereby selectively precipitate substantially all copper contained in said by-product as copper sulfide in the form of a copper-containing precipitate and to form a filtrate containing substantially no copper and having dissolved therein at least one metal selected from the group consisting of arsenic, zinc, iron and cadmium;
- (2) separating the copper-containing precipitate by filtration from the filtrate under conditions which do not cause the arsenic present in the filtrate to crystallize as arsenious acid;
- (3) cooling or concentrating the resulting filtrate to thereby precipitate crystals of arsenious acid;
- and
- (4) separating the precipitated arsenious acid crystals from the filtrate.
A method of recovering valuable metals from an industrial by-product that contains copper and arsenic, and at least one metal selected from the group consisting of lead, zinc, iron, silver and cadmium, at least part of said copper being present as acid-soluble copper in the form of at least one of oxides and sulfate, said method comprising the steps of:
- (1) leaching the by-product with sulfuric acid in an SO.sub.2 gas atmosphere at a temperature of at least 70.degree. C. in the presence of a solid sulfide or sulfur in an amount sufficient to precipitate all dissolved copper so as to maintain the solution substantially free of copper ions and to thereby selectively precipitate substantially all copper contained in said by-product as copper sulfide in the form of a copper-containing precipitate and to form a filtrate containing substantially no copper and having dissolved therein at least one metal selected from the group consisting of arsenic, zinc, iron and cadmium;
- (2) separating the copper-containing precipitate by filtration from the filtrate under conditions which do not cause the arsenic present in the filtrate to crystallize as arsenious acid;
- (3) adding hydrogen sulfide to said filtrate to thereby precipitate arsenic sulfide;
- and
- (4) separating the precipitated arsenious sulfide from said filtrate.
A method of recovering valuable metals from an industrial by-product that contains copper and arsenic, and at least one metal selected from the group consisting of lead, zinc, iron, silver and cadmium, at least part of said copper being present as acid-soluble copper in the form of at least one of oxides and sulfate, said method comprising the steps of:
- (1) leaching the by-product with sulfuric acid in an SO.sub.2 gas atmosphere at a temperature of at least 70.degree. C. in the presence of a solid sulfide or sulfur in an amount sufficient to precipitate all dissolved copper so as to maintain the solution substantially free of copper ions and to thereby selectively precipitate substantially all copper contained in said by-product as copper sulfide in the form of a copper-containing precipitate and to form a filtrate containing substantially no copper and having dissolved therein at least one metal selected from the group consisting of arsenic, zinc, iron and cadmium;
- (2) separating the copper-containing precipitate from the filtrate;
- (3) neutralizing the filtrate with a neutralizing agent so that the pH of the filtrate does not exceed 2.5 to thereby form a neutralized liquor;
- (4) adding hydrogen sulfide gas to the neutralized liquor to thereby precipitate at least one sulfide selected from zinc sulfide and cadmium sulfide;
- and
- (5) separating the precipitated sulfides from the neutralized liquor.
A method of recovering valuable metals from an industrial by-product that contains copper and arsenic, and at least one metal selected from the group consisting of lead, zinc, iron, silver and cadmium, at least part of said copper being present as acid-soluble copper in the form of at least one of oxides and sulfate, said method comprising the steps of:
- (1) leaching the by-product with sulfuric acid in an SO.sub.2 gas atmosphere at a temperature of at least 70.degree. C. in the presence of a solid sulfide or sulfur in an amount sufficient to precipitate all dissolved copper so as to maintain the solution substantially free of copper ions and to thereby selectively precipitate substantially all copper contained in said by-product as copper sulfide in the form of a copper-containing precipitate and to form a filtrate containing substantially no copper and having dissolved therein at least one metal selected from the group consisting of arsenic, zinc, iron, and cadmium;
- (2) separating the copper-containing precipitate from the filtrate;
- (3) neutralizing the filtrate with a neutralizing agent so that the pH of the filtrate does not exceed 2.5 to thereby form a neutralized liquor;
- (4) adding hydrogen sulfide gas into the first neutralized liquor to thereby precipitate at least one sulfide selected from zinc sulfide and cadmium sulfide;
- (5) separating the precipitated sulfides from the first neutralized liquor to thereby form a second neutralized liquor;
- (6) reacting the second neutralized liquor with air to thereby precipitate iron in the form of Fe.sub.3 O.sub.4 ;
- and
- (7) separating Fe.sub.3 O.sub.4 from the second neutralized liquor.
Dependencies are inferred from the claim text.