Weathering of Biotite in<i>Acidithiobacillus ferrooxidans</i>Cultures

Abstract

The purpose of this study was to assess the weathering of biotite under conditions simulating an active bioleaching environment. Finely ground biotite was contacted with Acidithiobacillus ferrooxidans culture solutions for up to 120 days. Biotite was altered under these conditions to interstratified structures comprised of mixed layers of biotite and vermiculite. Interlayer K in biotite was released upon weathering and precipitated with ferric iron and sulfate to form jarosite. Substantial dissolution of biotite was also associated with weathering. The data demonstrate that exposed, biotite-rich rocks in mine tailings and heap and dump leaching systems can undergo acid mediated solubilization and structural changes, which are coupled with the formation of expansive, vermiculite-like minerals and jarosite precipitation.