Recovery of zinc from geothermal brines
AssigneeMidAmerican Energy Holdings Company
InventorJohn L. Featherstone
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Abstract
Improved methods are disclosed for the efficient and cost-effective recovery of zinc metal from zinc-containing brines. Zinc is first bound to an anionic ion exchange resin (IX) which has been equilibrated with a solution containing a reducing agent, washed, and eluted with an elution solution. A reducing agent can be added to the brine prior to loading on the IX and can optionally be added to the IX after the washing step. The eluted zinc is extracted with a water-immiscible cationic organic solvent (SX), which is scrubbed, then stripped with concentrated acid. Substantially pure zinc is recovered by electrowinning the zinc-loaded concentrated acid solution.
Claims16
A method for recovering zinc metal from metal-containing brine comprising the steps of:
- (a) reducing the pH of the brine to at least 3.5 to form a pretreated brine;
- (b) loading the pretreated brine onto a zinc-binding ion exchange chromatography resin to form a zinc-charged resin;
- (c) washing the zinc-charged resin with an acidic aqueous salt solution to remove zinc-depleted brine;
- (d) eluting the zinc from the zinc-charged resin with an aqueous solution to form a zinc-containing eluant;
- (e) extracting the zinc from the zinc-containing eluant into an organic phase by mixing the zinc-containing eluant with a sufficient quantity of cationic organic solvent;
- and
- (f) removing the zinc from the organic phase by mixing the organic phase with an aqueous acidic solution.
A method for recovering zinc metal from metal-containing brine comprising the steps of:
- (a) reducing the pH of the brine to at least 3.5 to form a pretreated brine;
- (b) surrounding a zinc-binding ion exchange chromatography resin with a reducing agent;
- (c) loading the pretreated brine onto the zinc-binding ion exchange chromatography resin to form a zinc-charged resin;
- (d) washing the zinc-charged resin with an acidic aqueous salt solution to remove zinc-depleted brine;
- (e) eluting the zinc from the zinc-charged resin with an aqueous solution to form a zinc-containing eluant;
- (f) extracting the zinc from the zinc-containing eluant into an organic phase by mixing the zinc-containing eluant with a sufficient quantity of cationic organic solvent;
- and
- (g) removing the zinc from the organic phase by mixing the organic phase with an aqueous acidic solution.
Dependencies are inferred from the claim text.