Lead, zinc and manganese recovery from aqueous solutions
AssigneeCentaur Mining Exploration Limited
InventorRobert A. Geisler
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Abstract
Aqueous solutions containing lead, zinc and manganese are treated to recover these metals by sequential solvent extraction steps. Solvent extractants are selected to extract preferentially lead, then zinc and then manganese in that order. Any interfering metals are removed (as by ion exchange) before extraction. The loaded extractant phases are stripped with selected acids and lead, zinc and manganese each recovered from the strip solutions. Optionally calcium can be recovered when present. A preferred type of extractant (for lead especially) is substituted monothiophosphinic acids. A closed loop system is described which is advantageous with leachate from sulphide and carbonate ores.
Claims20
A process for recovering lead, zinc, and manganese from an aqueous solution containing these metals, comprising:
- (a) selecting solvent extractant able to preferentially extract lead in the presence of zinc and manganese, from the solution;
- (b) providing that the solution is free of interfering metals;
- (c) extracting the interferant-free solution with selected solvent extractant in an amount sufficient to extract the lead and separating the loaded extractant phase from the solution;
- (d) selecting solvent extractant able to preferentially extract zinc in the presence of manganese;
- (e) extracting the lead-free solution with selected solvent extractant in an amount sufficient to extract the zinc and separating the loaded extractant phase from the solution;
- (f) selecting solvent extractant able to preferentially extract manganese in the presence of any residual metals;
- (g) extracting the lead- and zinc-free solution with selected solvent extractant in an amount sufficient to extract the manganese and separating the loaded extractant phase from the solution;
- (h) separately stripping each loaded extractant phase to move lead, zinc and manganese into separate aqueous acid strip solutions;
- and
- (i) recovering, in a selected form, lead, zinc and manganese from the corresponding strip solutions.
A process for recovering lead, zinc, manganese and calcium from aqueous acetate solutions containing these but free of copper, iron, cadmium and cobalt, comprising:
- (a) extracting the aqueous solution at a pH of from 0.0 to 0.5 with an organic phase comprising substituted monothiophosphinic acid to extract lead;
- (b) extracting the lead-free aqueous solution at a pH of from 1.0 to 1.2 with an organic phase comprising at least one of substituted monothiophosphinic acids, disubstituted-phosphoric and -phosphorothioic acids, and C26 H34 SN2O2 to extract zinc;
- (c) extracting the lead- and zinc-free aqueous solution at a pH of from 3.0 to 3.5 with an organic phase comprising at least one of substituted monothiophosphinic acids, disubstituted phosphinic acids, and disubstituted-phosphoric and -phosphorothioic acids to extract manganese;
- (d) stripping each of the loaded organic phases with an aqueous acid solution comprising one acid from the group consisting of acetic, nitric, hydrochloric and sulphuric except that sulphuric may be selected only for Mn stripping;
- (e) electrowinning lead, zinc and manganese from their respective strip solutions and recycling the strip acids to step (d);
- (f) treating the remaining aqueous solution containing calcium, as acetate or hydroxide, with carbon dioxide to precipitate calcium carbonate;
- (g) recovering and recycling acetic acid to form starting solution;
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- (h) recovering lead, zinc and manganese as oxides and a precipitate comprising calcium carbonate.
Dependencies are inferred from the claim text.