| 摘要 |
<p>Zinc salt solns. with high purity are made from impure solns. (1), esp. contg. As and obtd. by ammoniacal leaching of materials such as fly-ash, dross, sweepings, or ball-mill dust. Solvent extn. is used in a closed circuit followed by the recovery of Zn, e.g. as oxide or carbonate. Soln. (1) is treated with Zn dust to ppte. metals which are more electropositive than zn, e.g. Cu. The ammoniacal soln. is treated with a liq. organic cation exchanger, with a min. capacity of 1 g/l for Zn, in mixer-settling units. The Zn in the organic phase is then scrubbed with a soln. (2) of NH3 + NH4NO3 for extn. of the Zn which has a high purity and is recovered in a conventional manner. The scrubbed organic phase is then recycled for liq.-liq. extn.</p> |
