Passive dolomitic drain treatment

Passive treatment of contaminated mining water is a major challenge in Quebec. In this context, the main objective of this research project is to evaluate a passive chemical treatment approach using modular drains containing high-purity natural dolomite CaMg(CO3)2 and semi-calcined dolomite Ca(CO₃)-MgO. Passive mine effluent treatment plants are favored for their low construction, operation and maintenance costs, in addition to possible implementation in remote areas, since their operational requirements are limited. However, deployment constraints include: adapting to seasonal variations in flow and contaminant load, correctly estimating their lifespan, hydraulic problems (clogging) and terrain topography. Passive treatment of mine effluent involves processes (chemical, physical and biological) found in the environment. Chemical methods aim to increase pH and precipitate metals. The neutralizer used in this project is high-purity natural dolomite CaMg(CO3)2, an under-utilized mineral effective for the removal of : As, Cd, Co, Cu, Pb. Thermal activation of dolomite by heating for 1 hour at 700-800°C enables its partial decomposition into Ca(CO₃)-MgO, which considerably increases its effectiveness as a neutralizer and for the removal of : As, B, Ba, Co, Cr, Hg, Mn, Ni, Pb, Sn, Sr, Ti, V, Zn. Project funded under the FRQ research program “sustainable development of the mining sector-III 1st competition - 2023-2024”.