Coal acid mine drainage treatment using cement kiln dust

Abstract

Sulphurs are present in different rocks. During mining activities and the sulphur removal processes Acid Mine Drainage (AMD) may be produced, by sulphate ions (SO4 2-) in solution. AMDs are the main source of pollution from mining operations and in Colombia their discharge into natural bodies of water must comply with national environmental regulations (pH between 5 and 9). Cement Kiln Dust (CKD), with calcium carbonate as its main component, from a Cementos Argos S.A. plant was used to neutralize an AMD generated through a coal bio-desulphurization process. Neutralized AMDs had pH values between 7.72 – 8.05 and the sulphates removal ranged from 67% to 70%. Precipitated sludge was dried and analyzed in order to determine its chemical and mineralogical composition. Moisture content was between 69% and 81%; this precipitated material was composed of gypsum with approximately 50% purity, as well as calcium carbonate. This composition makes it suitable for use in cement production.