Recovering lead from cupel waste generated in gold analysis by Pb-Fire assay.
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2016
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Because of its precision and accuracy, Pb-Fire assay is the most employed method for gold analysis in
geological materials. At the second stage of the method, namely cupellation, lead is oxidized to PbO
which is absorbed by the cupel, leading to metallic gold as a tiny bend at the bottom of the recipient.
After cupellation, cupel becomes highly contaminated with lead, making its disposal a serious risk of
environmental contamination. In the present work, a leaching process for removing lead from cupel
waste is proposed, which allowed for removing 96% of PbO by weight. After a precipitation step, 92.0% of
lead was recovered from leachates in the form of PbSO4. Lead in the solid wastes left by the extraction
was above the limit established by Brazilian legislation and these were classified as non-hazardous.
Finally, secondary effluents generated after the precipitation step presented lead content more than
twenty times lower than that of leachates from cupel waste. Tons of cupel waste are annually generated
from gold analysis by Pb-Fire assay. Thus, the proposed method can contribute to prevent the discharge
of high amounts of lead into the environment. Also, recovery of lead can help to partially meet the industrial
demand for lead compounds.
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Cupellation, Leaching
Citação
CERCEAU, C. I. et al. Recovering lead from cupel waste generated in gold analysis by Pb-Fire assay. Journal of Environmental Management, v. 183, p. 771-776, 2016. Disponível em: <http://www.sciencedirect.com/science/article/pii/S0301479716305904?via%3Dihub>. Acesso em: 15 set. 2017.