British Columbia Mine Reclamation Symposium

Alkaline by-products as amendments for stabilization and neutralization of oxidized sulphidic mine waste deposits Sartz, Lotta; Bäckström, Mattias; Karlsson, Stefan


Stabilization of oxidized sulphidic mine waste deposits with alkaline by-products could be a way of controlling ARD. Mixtures of alkaline by-products (10% by volume) and oxidized waste rock have been studied during six months in 30 L experimental drums. Alkaline by-products are: lime mud (LM), green liquor dreg (GLD), lime kiln dust (LKD), LD slag (LD), water work granules (WWG), carbonized fly ash (FAE) and fresh fly ash (FAF). The experiments are fed with water once a week to imitate natural precipitation. pH of the reference (no alkaline amendment) is below 3 and trace metal concentrations are 2000 mg/l, 4 mg/l and 1 mg/l for Zn, Cd and Pb respectively. LKD, LM and LD amended systems (pH 6.7-7.5) are the most efficient for Cd- and Zn-removal (reduction at least 99 % compared to the reference), while GLD (tap pH 6.5) is the most efficient for Pb-removal (99 % reduction compared to the reference). FAE amended system only reaches pH around 5 and accordingly trace metal reduction is rather low. Geochemical simulations using PHREEQC indicate equilibrium with otavite and smithsonite in the WWG and GLD systems, whereas cerrusite is at equilibrium in the LKD, WWG and GLD systems.

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