Recovery of lead and silver from minerals and process residues

In a process for gaining lead and silver values comprising the steps of (1) preparing a solution of lead chloride and silver compounds by dissolving lead sulphate and silver compounds contained in an ore or process residue in an acidic, concentrated chloride brine;

• (2) separating the solution so formed from insoluble gangue or other residue;
• (3) forming a precipitate of lead oxychloride and silver compounds by adding lime to said solution and separating said precipitate from the residual lean brine solution for recycling said lean brine for reuse in the further extraction of lead sulphate as under steps (1) and (2);
• the improvement which comprises (5) reacting the said oxychloride precipitate with oxygen and lime in a reactor at a temperature above 325.degree. C. for longer than one half hour to produce a calcine containing most of the lead as calcium plumbates and/or lead oxides and most of the silver as silver or silver compounds;
• (6) repulping said calcine in water and/or dilute chloride brine to dissolve soluble chlorides;
• (7) separating the residue obtained in step (6) from the resulting chloride brine;
• (8) recycling the brine resulting from (7) for reuse in the further extraction of lead sulphate as under steps (1) and (2);
• (9) washing said residue containing calcium plumbates and/or lead oxides, as well as silver and silver compounds resulting from step (7) with fresh water to remove residual chlorides;
• and (10) recycling the chloride brine obtained in step (9) to step (6) and/or recycling the said chloride brine for reuse in the further extraction of lead sulphate as under steps (1) and (2).

A process comprising the steps of (1) preparing a solution of lead chloride by dissolving lead sulphate contained in an ore or process residue in an acidic, concentrated chloride brine;

• (2) separating the solution so formed from insoluble gangue or other residue;
• (3) forming a precipitate of lead oxychloride by adding lime to said solution and separating said lead oxychloride precipitate from the residual lean brine solution;
• (4) reacting the said oxychloride precipitate with oxygen and lime in a reactor in an elevated temperature to produce a calcine containing most of the lead as calcium plumbates and/or lead oxides;
• (5) washing said calcine in water and/or dilute chloride brine to dissolve soluble chlorides;
• (6) separating the resulting residue obtained from the resulting chloride brine;
• and, (7) washing said residue containing calcium plumbates and/or lead oxides with fresh water to remove residual chlorides.

A process for gaining lead and silver values comprising the steps of (1) preparing a solution of lead chloride and silver compounds by dissolving lead sulphate and silver compounds contained in an ore or process residue in an acidic, concentrated chloride brine;

• (2) separating the solution so formed from insoluble gangue or other residue;
• (3) forming a precipitate of lead oxychloride and silver compounds by adding lime to said solution and separating said precipitate from the residual lean brine solution;
• (4) reacting the said oxychloride precipitate with oxygen and lime in a reactor at an elevated temperature to produce a calcine containing most of the lead as calcium plumbates and/or lead oxides and most of the silver as silver or silver compounds;
• (5) washing said calcine in water and/or dilute chloride brine to dissolve soluble chlorides;
• (6) separating the resulting residue from the resulting chloride brine;
• and, (7) washing said residue containing calcium plumbates and/or lead oxides, as well as silver and silver compounds, with fresh water to remove residual chlorides.

In a process comprising the step of (1) forming a precipitate of lead oxychloride by adding lime to a chloride brine solution containing lead chloride, and separating said lead oxychloride precipitate from the residual lean brine solution;

• the improvement which comprises (2) reacting the said oxychloride precipitate with oxygen and lime in a reactor at a temperature above 325.degree. C. for longer than 0.5 hours to produce a calcine containing most of the lead as calcium plumbates and/or lead oxides;
• (3) repulping said calcine in water and/or dilute chloride brine to dissolve soluble chlorides;
• (4) separating the residue obtained in step (3) from the resulting chloride brine;
• and (5) washing said residue containing calcium plumbates and/or lead oxides resulting from step (4) with fresh water to remove residual chlorides.