A COMPARATIVE STUDY ON THE DISSOLUTION AND SOLUBILITY OF CALCITE RHODOCHROSITE SMITHSONITE AND OTAVITE AT 25°C.

The solubility products for calcite-group minerals are very important to interpretate their behavior in natural water, which have a great influence on the migration and transformation of heavy metals in the environment. But discrepant solubility values for these minerals were reported previously. In the present work, calcite, rhodochrosite, smithsonite and otavite were prepared, and their dissolution processes lasting nine months were then experimentally investigated. After the 5040h dissolution in the airsaturated water, the aqueous concentrations of Ca, Mn, Zn and Cd attained the steady state of 0.511 ~ 0.562 mmol/L for calcite, 0.211 ~ 0.234 mmol/L for rhodochrosite, 0.277 ~ 0.314 mmol/L for smithsonite and 0.00346 ~ 0.00648 mmol/L for otavite, respectively. For the dissolution in the N2-degassed water, the air-saturated water and the CO2-saturated water Ksp) and the Gibbs free energies of formation mated to be -8.38±0.07 ~ -8.43±0.04 and -1129.27 ±0.40 ~3), -10.18±0.04 ~ -10.29±0.12 and -814.00±0.22 ~ - 3), -10.70±0.04 ~ -10.50±0.09 and -735.97±0.25 ~ -3), -11.55±0.08 ~ -11.71±0.11 and -671.40±0.46 ~ -672.30±0.64 kJ/mol for otavite CdCO3), respectively. [ABSTRACT FROM AUTHOR]