Abstract
Feeding ores and tailing slime from Pb-Zn deposits hosted in rhyolites and carbonates-rich sedimentary rocks were studied chemically by ICP/MS. The rhyolite-hosted one at Na Son is rich in Pb (Pb/Zn=4.1), and also rich in such chalcophile elements as Cd, In, Cu, Co, Ni, Bi, Ag, Sb and Se. Important pollutants of Pb, Cd and As are well decreased in the tailing slime. REEs contained as cerianite are all moved to the tailing slime.
Pb-Zn ores from the Cho Dien sedimentary area are rich in chalcophile elements such as Cd, In, As, Ag, and also Fe. Recovery rates of the flotation are high in the Zn (58%) and thus Cd (64%), and also lead (92%). Arsenic and iron are high in both the feeding ores and tailing slime, implying these are contained as arsenopyrite and transported to the tailing ponds. Pb-Zn ores from the Lang Hich sedimentary area have high Zn/Pb and Cd/Zn ratios, but are poor in chalcophile elements, and Fe and Mn. About 87 % Zn and 88 % Cd of the ores are recovered by the flotation. Arsenic and Fe are originally low with averages of 185 ppm As and 1.15 %Fe; all moved to the tailing pond.
