Neutralização de Drenagem Ácida de Rochas com Lama Vermelha de Bauxita: Ensaios de Batelada em Laboratório

Abstract

Acid Rock Drainage (ARD) is one of the world's most challenging environmental issues. Alkaline amendments to barriers for ARD prevention or direct ARD alkaline treatment have been routinely used for ARD management. In turn, bauxite red mud (BRM) is an alkaline residue from the alumina industry, with annual average production close to 120 million tons. So the use of BRM for ARD neutralization seems to be a good alternative and must be investigated. The main objective of this experiment is to assess suitable proportions of BRM to treat ARD under the perspective of waste management procedures. So, laboratory short-term batch equilibrium tests were carried out using different volumetric and mass proportions. The use of a volumetric approach was intended to simulate the mixture of BRM pulp with the ARD liquid solutions, while the mass approach refer to the mixtures of dewatered BRM and ARD. The pH and metal removal percentage, called here as extraction, were respectively used as neutralization and treatment efficiency parameters. The results have showed that BRM was efficient for ARD neutralization on BRM volumetric proportions greater than 60% and solid (BRM):liquid(ARD) ratio of 1:1.5. This ratio result on extraction values greater than 90% for most of the ARD chemicals.