Reaction Product Coatings On Limestone/Calcite and on Non-Reactive Minerals in Contact with Acidic Waters Containing Various Metal Ions

Ranich, Richard L. ; Aplan, Frank F. ; Hiskey, J. B. ; Scheiner, B. J. ; Thompson, Robert S.
Organization: Society for Mining, Metallurgy & Exploration
Pages: 14
Publication Date: Jan 1, 1993
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Acidic waters typified by acid mine drainage, copper dump leach solutions and steel pickle liquors will typically contain SO4-2 and cations such as Fe+3, AI+3 and for the pickle liquors, sometimes Cr+3. These acidic waters will often react with limestone, present naturally or introduced for purposes of solution neutralization, to form reaction - inhibiting coatings of gypsum and gelatinous, metal hydroxide precipi¬tates. The coating thickness, as a function of pH, was quantified for both reactive (calcite, limestone) and non-reactive (quartz, barite, fluorite) minerals, and the data were related to the hydroxy species diagrams and to solution turbidity measurements. Coatings were found on the reactive minerals at a lower bulk solution pH than on the non-reactive minerals.
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