Dissolution of natural serpentinite in mineral and organic acids
Abundant resources of magnesium silicates make an interesting prospect for long-term storage of CO2by mineral carbonation.
Several carbonation processes proposed in literature for CO2storage employ extraction of silicate minerals using a liquid solvent.
In this study, the dissolution of natural serpentinite in respective solutions of acids, bases and ammonium salts has been
investigated. Experiments performed at room temperature showed that H2SO4was most efficient at extracting magnesium from
serpentinite, followed by HCl, HNO3, HCOOH and CH3COOH. Experiments for determining the dissolution kinetics was
performed at temperatures of 30, 50 and 70 °C in 2 M solutions of H2SO4, HCl, and HNO3. At 70 °C temperatures all magnesium
was extracted from serpentinite in each of the three acid solutions tested during 1–2 h. Also a large part of iron in serpentinite was
extracted, while very little silicon dissolved (b4%). The dissolution rate seemed to be limited by product layer diffusion for
serpentinite particles with a size distribution of 74–125 μm. The apparent activation energies were 68 kJ mol−1for dissolution in
H2SO4, 70 kJ mol−1for dissolution in HCl, and 74 kJ mol−1for dissolution in HNO3.
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