Author(s)

A. C. Q. Ladeira & C. R. Gonçalves

Abstract

This work is aimed at the selection of an appropriate adsorbent for uranium and manganese present in acid mine water drainage. The pH of the acid water is around 2.7, the uranium concentration is in a range of 9-15mg/L, the manganese concentration approximately 170mg/L and the sulphate concentration is near 2000mg/L. The uranium in this solution, where sulphate is present in high levels, is basically in the form of UO2(SO4)3 -4 and the manganese is in the form of Mn+2. The removal of these elements has been studied using activated carbons, gibbsite, zeolite, apatite and biological adsorbent. Among all adsorbents tested, the biological material was the one which presented the best performance taking into account the necessity of removing Mn and U simultaneously. The maximum adsorption capacity varied from 10 to 14 mg U.g-1 and 83 to 123mg Mn.g-1. The results, obtained by column experiments, showed that the sulphate had a deleterious effect on the uranium recovery by the biological adsorbent. Mn removal was increased with the increase of pH from 2.6 to 7.0. Adsorption of these elements by activated carbons, gibbsite, zeolite and apatite was lower if compared to the biological material. Keywords: manganese, uranium, adsorption, removal, acid mine. 1 Introduction Acid mine drainage (AMD) is one of the main environmental problems faced by the mining industry and, once installed, may last for thousands of years. This phenomenon occurs due to the oxidation of sulphite minerals when exposed to oxygen and water, and produces dissolved metals, sulphate and acidity. As well as having distinct areas with serious AMD generation (coal and uranium mines) Brazil has other regions that deserve detailed evaluation (copper, gold and nickel

Keywords

manganese, uranium, adsorption, removal, acid mine.