Extraction of antimony from antimony sulfides bearing solids

A method of extracting antimony from antimony sulfide bearing solids and recovering the antimony as sodium antimonate which comprises the steps of

• (a) leaching the antimony values from the solids with an aqueous basic solution containing sodium hydroxide to form an antimony-containing solution and a gangue,
• (b) separating the leach solution from the gangue,
• (c) adding a catalyst comprising a water-soluble copper salt, a quinone, a hydroquinone, or mixtures of one or more of these to the leach solution,
• (d) passing oxygen through the leach solution containing the catalyst whereby the antimony present is oxidized to pentavalent antimony and sodium antimonate precipitates from the solution, and
• (e) recovering the solid sodium antimonate.

A method of extracting antimony from antimony sulfide bearing solids and recovering pentavalent antimony as potassium antimonate which comprises the steps of

• (a) leaching the antimony values from the solids with a solution of potassium hydroxide in water to form an antimony containing solution and a gangue,
• (b) separating the leach solution from the gangue,
• (c) adding a catalyst comprising a mixture of water-soluble copper salt and a hydroquinone to the leach solution,
• (d) passing oxygen through the leach solution containing the catalyst whereby the antimony present is oxidized to pentavalent antimony and water-soluble potassium antimonate is formed.

A method of extracting antimony from antimony sulfide and arsenic bearing solids and recovering the antimony as a water-insoluble metal antimonate substantially free of arsenic which comprises the steps of

• (a) leaching the antimony values from the solids with a solution of potassium hydroxide in water to form an antimony containing solution and gangue,
• (b) adding a catalyst comprising a water-soluble copper salt, a quinone, a hydroquinone, or mixtures of one or more of these to the leach solution,
• (c) passing oxygen through the leach solution containing the catalyst whereby the antimony present is oxidized to pentavalent antimony and water-soluble potassium antimonate is formed,
• (d) separating the oxidized solution from the gangue and other solids,
• (e) adding a water-soluble metal salt, to the solution to from and precipitate the water-insoluble metal antimonate.

A method of extracting antimony from antimony sulfide bearing solids and recovering the antimony as antimony trioxide which comprises the steps of

• (a) leaching the antimony values from the solids with an aqueous basic solution containing sodium hydroxide and sodium sulfide to form an antimony-containing solution and a gangue,
• (b) separating the leach solution from the gangue,
• (c) adding a catalyst comprising a water-soluble copper salt, a quinone, a hydroquinone, or mixtures of one or more of these to the leach solution,
• (d) passing oxygen through the leach solution containing the catalyst whereby the antimony present is oxidized to pentavalent antimony and sodium antimonate precipitates from the solution,
• (e) adjusting the pH of the mixture obtained in (d) to a pH of from about 1 to about 6 by the addition of one or more acids,
• (f) stirring and heating the mixture at a temperature of from about 25.degree. C to about 75.degree. C,
• (g) separating and collecting the solids in the heated mixture, and
• (h) heating the collected solids to form antimony trioxide.