Silver recovery by ion exchange
View Patent ↗The present invention according provides a method of recovering silver from silver containing halide solutions, comprising the steps of: (a) providing an ion exchange column comprising a weak anion exchange resin; (b) introducing the silver containing halide solution to the ion exchange column to absorb silver in the weak anion exchange resin; (c) washing the loaded ion exchange resin with a first washing solution to rinse off absorbed zinc and optionally at least part of copper; (d) washing the loaded ion exchange resin with a second washing solution to rinse off remaining copper; and (e) optionally washing the loaded ion exchange resin with a third washing solution to rinse off absorbed lead; and (f) eluting the loaded ion exchange resin with an eluent to remove silver from the resin and to obtain a silver containing solution.
1. A method of recovering silver from silver containing halide solutions, comprising:
(a) providing an ion exchange column comprising a weak anion exchange resin;
(b) introducing the silver containing halide solution to the ion exchange column to absorb silver in the weak anion exchange resin;
(c) washing the loaded ion exchange resin with a first washing solution to rinse off absorbed zinc and optionally at least part of copper;
(d) washing the loaded ion exchange resin with a second washing solution to rinse off remaining copper; and
(e) optionally washing the loaded ion exchange resin with a third washing solution to rinse off absorbed lead; and
(f) eluting the loaded ion exchange resin with an eluent to remove silver from the resin and to obtain a silver containing solution.
2. The method as claimed in claim 1 , further comprising:
(g) treating the ion exchange resin with an acidic solution to protonate the resin and to obtain a protonated resin.
3. The method as claimed in claim 2 , wherein the acidic solution in step (g) is a hydrochloric acid solution.
4. The method as claimed in claim 1 , wherein the silver containing halide solution comprises 0.1 to 1500 mg/L silver.
5. The method as claimed in claim 1 , wherein the silver containing halide solution comprises 100 to 300 g/L.
6. The method as claimed in claim 1 , wherein the halide is chloride.
7. The method as claimed in claim 1 , wherein the silver containing halide solution further comprises 0 to 80 g/L bromides.
8. The method as claimed in claim 1 , wherein the silver containing halide solution is obtained by leaching silver containing ore and/or concentrate with an acidic aqueous leaching liquor comprising 10 to 110 g/L Cu 2+ , 50 to 300 g/L Cl − , and 1 to 80 g/L Br − .
9. The method as claimed in claim 1 , wherein the pH of the silver containing halide solution is below 3.
10. The method as claimed in claim 1 , wherein a backbone of the weak anion exchange resin is a macroporous matrix.
11. The method as claimed in claim 10 , wherein the backbone of the weak anion exchange resin is amorphous silica.
12. The method as claimed in claim 1 , wherein the weak anion exchange resin comprises amine groups as anion-exchange functional groups.
13. The method as claimed in claim 1 , wherein the first washing solution is water or an aqueous solution comprising NaCl and/or CaCl 2 .
14. The method as claimed in claim 1 , wherein the second washing solution is an aqueous solution comprising a hydrochloric acid.
15. The method as claimed in claim 1 , wherein the third washing solution is an aqueous solution comprising an aminopolycarboxylic acid or salt thereof.
16. The method as claimed in claim 15 , wherein the aminopolycarboxylic acid is ethylenediaminetetraacetic acid (EDTA).
17. The method as claimed in claim 1 , wherein the eluent is an acidic solution comprising thiourea (SC(NH 2 ) 2 ).
18. The method as claimed in claim 17 , wherein the concentration of thiourea is from 1 to 5 wt %.
19. The method as claimed in claim 1 , wherein the eluent is an aqueous solution containing one or more thiosulfate salt and optionally Na 2 SO 3 .