Dissolution and Solubility of the Calcite–Otavite Solid Solutions [(Ca1?xCdx)CO3] at 25 °C

A complete series of the calcite–otavite solid solutions [(Ca1?xCdx)CO3] were prepared, and their dissolution processes lasting nine months experimentally investigated. For in N2-degassed water, Ca concentrations aqueous phases increased up to steady states after 5040 h dissolution, Cd highest values then decreased gradually 0.017–6.476 ?mol/L dissolution. CO2-saturated peak 0.94–0.46 mmol/L 0.046–9.643 respectively. water at 25 °C, mean solubility products (log Ksp) Gibbs free energies formation (?Gf?) estimated be ?8.45–?8.42 ?1129.65–?1129.48 kJ/mol for calcite [CaCO3] ?11.62–?11.79 ?671.81–?672.78 otavite [CdCO3], Generally, log Ksp non-linearly, ?Gf? linearly with increasing Cd/(Ca+Cd) mole ratio (XCd) (Ca1?xCdx)CO3 solutions. In Lippmann diagrams constructed sub-regular Guggenheim coefficients a0 = ?0.84 a1 ?3.80 or ?1.12 ?3.83 dissolved incongruently, moved progressively quasi-equilibrium curves along curve from right left, approached solutus finally reached minimum stoichiometric saturation calcite. The considerably Cd-poor equilibrium CdCO3-rich phases.