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Method for recovering anhydrous ZnCl2 from aqueous solutions.

Authors
Eichbaum-BR; Schultze-LE
Source
Reno, NV: U.S. Department of the Interior, Bureau of Mines, RI 9347, 1991 Jan; :1-10
Link
NIOSHTIC No.
10008557
Abstract
To develop technology to assure an ample supply of zinc and to reduce environmental pollution, the U.S. 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 (ZnCl2). The process involves high energy requirements for evaporating the pregnant solution to produce anhydrous ZnCl2 needed for electrolytic cell feed. An efficient hydrometallurgical process would facilitate treatment of lower grade ores than can be used in conventional processing and would render roasting unnecessary. An alternative method was devised for recovering ZnCl2 from solution. Zinc diammine chloride (Zn(NH3)2Cl2) was precipitated from solution by adding ammonium chloride (NH4Cl) and sparging with ammonia (NH3) to a pH of 6 to 7.5. The spent solution was treated with calcium hydroxide (Ca(OH)2) at 60 to 80 C for 1 to 4 h to remove remaining zinc and NH3. The Zn(NH3)2Cl2 was heated to 300 to 400 C to remove NH3 and produce anhydrous ZnCl2. A possible flowsheet was devised and is included.
Keywords
Air-pollution-abatement; Performance-evaluation; Energy-conservation; Extraction-metallurgy; Process-charting; Separation-processes; Decomposition; Leaching; Substitutes; Hydrometallurgy; Crystallization; Materials-recovery; Zinc-chlorides; Aqueous-solutions; Zinc
Publication Date
19910101
Document Type
IH; Report of Investigations
Fiscal Year
1991
NTIS Accession No.
NTIS Price
Identifying No.
RI-9347
NIOSH Division
RERC
Source Name
Reno, NV: U.S. Department of the Interior, Bureau of Mines, RI 9347
State
NV
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