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4269980 
Journal Article 
Liming of acid surface waters: Effect of water constituents and material impurities on calcite dissolution kinetics 
Schipek, M; Merkel, BJ 
2012 
275-283 
WOS:000398883700031 
Using limestone instead of soda or lime as neutralizing product during lake water treatment has additional economic and ecological benefits. Dissolution kinetics of pure calcite is well investigated. However the composition of natural carbonates as well as the constituents in mine waters have strong influence on solution kinetics and may inhibit dissolution processes during lake remediation. 25 different neutralisation products were tested and investigated by XRF and SEM-EDX. The reactivity of synthetic marble powder and two industrial products (KSM Beroun, CC20) was investigated in a free-drift batch-experiment by adding different amounts of inhibiting ions.



Based on the elemental contents, no significant difference between synthetic marble powder and industrial products was found. Significant deviations from the theoretical model after Plummer et al. (1978) were noticeable during kinetic experiments with limestone in pure water. Additionally, ions typical for acid mine drainage (e.g. Mn2+, Cd2+, Fe3+, SO42-) can have different effects on the kinetics of carbonate dissolution. Manganese concentrations typical for acidic mining lakes (8.98x10(-4) mmol/L) inhibit calcite dissolution and result in 66.4% of dissolved calcium compared to the experiments without inhibitor. Supplying excess calcite (20 times excess instead of 5 times with respect to calcite carbon dioxide equilibrium) results in 92.7% of the equilibrium concentration and a significant time-shift in reaching equilibrium. Cadmium has also a significant influence on the dissolution and kinetics. Only 58.2% of the calcium concentration was reached with cadmium as inhibitor (7.65x10(-6) mmol/L) compared to the dissolution of pure water. Using 20 times more carbonate revealed a slightly higher dissolution reaction (63.8%).



Material impurities and water constituents significantly affect the dissolution kinetics of limestone. Thus, both should be considered if there are ambitious efforts to remediate acidic mining lakes by in-lake liming. 
in-lake liming; acid mine drainage; inhibition; lime; kinetics