Dissolution kinetics of fosteritic olivine at 90-150 degrees C including effects of the presence of CO2

摘要

The steady state dissolution rate of San Carlos olivine [Mg1.82Fe0.18SiO4]in dilute aqueous solutions was measured at 90, 120, and 150 degrees C and pH ranging from 2 to 12.5. Dissolution experiments were performed in a stirred flow-through reactor, under either a nitrogen or carbon dioxide atmosphere at pressures between 15 and 180 bar. Low pH values were achieved either by adding HCl to the solution or by pressurising the reactor with CO2, whereas high pH values were achieved by adding LiOH. Dissolution was stoichiometric for almost all experiments except for a brief start-up period. At all three temperatures, the dissolution rate decreases with increasing pH at acidic to neutral conditions with a slope of close to 0.5; by regressing all data for 2 <=, pH <= 8.5 and 90 degrees C <= T <=, 150 degrees C together, the following correlation for the dissolution rate in CO2-free solutions is obtained: