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Gallium extraction from zinc plant residues by chlorination roasting
Iriarte Aguirre, Santiago
Iriarte Aguirre, Santiago
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2023
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2024-11-29
Abstract
The demand for semiconductors and the renewable energy transition has increased the demand for
gallium, indium, and germanium. The US Department of Energy considers these elements critical due to
their scarcity, lack of substitutes, and import dependence. Some sphalerite concentrates contain trace
amounts of Ga, In, and Ge. During the processing of sphalerite, Ga, In, and Ge are concentrated during
leaching. However, Ga, In, and Ge co-precipitate with the iron sulfates and other impurities during the
iron removal stage. These zinc processing residues are promising sources for Ga, In, and Ge; however, there
are technological limitations to recovering these elements. Chlorine metallurgy has been studied to recover
metals from complex ores, treat waste, or recover critical elements in waste streams. It has been evaluated
for the recovery of valuable material from sulfides, oxides, and silicate ores. Moreover, chlorine metallurgy
offers several advantages, such as opening ores, selectivity, regeneration of the chlorinating agents, and
process versatility. Thus, the following study presents chlorination roasting as a possible method to recover
gallium from domestic zinc processing residues. The study consists of chlorination roasting of two different
zinc processing residues for the recovery of gallium. The study discusses the effects of temperature and
chlorine gas concentration on the extraction via chloride fuming of Ga, Fe, Pb, and Zn. Gallium
extractions of 50%, 60 %, and 80 % were achieved from zinc processing residues. Moreover, zinc extractions
of 60% and 80% were also achieved. Selective volatilization of gallium, germanium, and indium chlorides
was studied and found to be a promising approach for refining.
A preliminary flow sheet for gallium recovery from zinc processing residues via chlorination roasting
was identified and evaluated. The preliminary techno-economic analysis found that the gallium grade in
the zinc processing residues is crucial for an economically feasible process. It was determined that
chlorination roasting is a technologically feasible process for the recovery of gallium.
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