Method for recovering anhydrous ZnCl{sub 2} from aqueous solutions
- Bureau of Mines, Reno, NV (United States)
To develop technology to assure an ample supply of zinc and to reduce environmental pollution, the US Bureau of Mines investigated alternatives to the roast-leach process for treating complex sulfide concentrates. Previous studies proved that low-grade zinc sulfide (ZnS) concentrates could be leached using chlorine-oxygen to produce zinc chloride (ZnCl{sub 2}). The process involves high energy requirements for evaporating the pregnant solution to produce anhydrous ZnCl{sub 2} needed for electrolytic cell feed. An efficient hydrometallurgical process would facilitate treatment of lower grade ores that can be used in conventional processing and would render roasting unnecessary. It is difficult to keep ZnCl{sub 2} anhydrous as it is hygroscopic and deliquescent. Therefore, an alternate method of producing a feed material from solution, which could be stored without absorbing H{sub 2}O, was sought. Zinc diamine chloride [Zn(NH{sub 3}){sub 2}Cl{sub 2}], was precipitated from solution by adding ammonium chloride (NH{sub 4}Cl) and sparging with ammonia (NH{sub 3}) to a pH of 6 to 7.5. The spent solution was treated with calcium hydroxide [Ca(OH){sub 2}] at 60{degrees} to 80{degrees}C for 1 to 4 h to remove remaining zinc and NH{sub 3}. The Zn(NH{sub 3}){sub 2}Cl{sub 2} was heated to 300{degrees} to 400{degrees}C to remove NH{sub 3} and produce anhydrous ZnCl{sub 2}. A possible flowsheet was devised and is presented.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 145154
- Report Number(s):
- CONF-911049-; ISSN 0149-6395; TRN: TRN: 93:000018-040
- Journal Information:
- Separation Science and Technology, Vol. 28, Issue 1-3; Conference: 7. symposium on separation science and technology for energy applications, Knoxville, TN (United States), 20-24 Oct 1991; Other Information: PBD: Jan-Feb 1993
- Country of Publication:
- United States
- Language:
- English
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