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Valuable metal selective sepn. without jarosite or double salt formation - by neutralising organic extn. soln. and exchanging ammonium or alkali ions in extractant with metal ions before main extn. stage
Valuable metal selective sepn. without jarosite or double salt formation - by neutralising organic extn. soln. and exchanging ammonium or alkali ions in extractant with metal ions before main extn. stage
In the selective sepn. of valuable metals (I) in a solvent extn. stage of an acid lixiviation process, the formation of jarosite and ammonium or alkali double salts is prevented by (a) neutralising the organic extn. soln. (II) with ammonium or alkali salt before the main sepn. of (I) by solvent extn.; (b) pre-extn. of (II) by contacting the extractant (III) with an aq. soln. contg. a metal (IV) as exchange ion to replace ammonium or alkali ions in (II); and (c) contacting (II) with the aq. soln. contg. (I) in a main extn. stage. Pref. (III) is a di-(alkyl)-phosphinic acid ( IA), pref. a di-(2,4,4-trimethyl-pentyl)-phosphinic acid (IIIA-1), a monoalkyl ester of an alkylphosphonic acid or a di-(alkyl)-phosphoric acid; and (IV) is Mg. At least one (I) is more strongly extracted than (II), so that the latter is returned to the aq. soln.; and at least one (I) is more strongly extracted than other (I). The most strongly extracted (I) is Co (in mixts. with Ni) or one of Zn, Mn, Cd, Cu, Fe, V, Mo and U, esp. in mixts. in which the least strongly extracted is Cu or Mn. USE/ADVANTAGE - The process is useful in the sepn. of Co and Ni or of Zn, Mg, Cd, Cu, Fe, V, Mo or U, esp. from Cu or Mn (claimed). Removal of ammonium and alkali ions makes it possible to use higher temps. to intensify the lixiviation process and protects the environment.
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