Abstract
Feeding ores and tailing slime from representative Pb-Zn deposits hosted in Paleozoic carbonates-rich sedimentary rocks and Triassic rhyolites were studied chemically by ICP/MS. The Pb-Zn ores from the Cho Dien sedimentary area, called Cho Dien type, 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. The Pb-Zn ores from the Lang Hich sedimentary area, Lang Hich type, 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 wt.% Fe; all moved to the tailing pond. The rhyolite-hosted ores at Na Son mine are rich in Pb (Pb/Zn=4.1), and also rich in some lithophile components (e.g., REE) and such chalcophile elements as Cd, In, Cu, Co, Ni, Bi, Ag, Sb and Se, but very low in As. Important pollutants of Pb, Cd and As are well decreased in the tailing slime.
