Alkalization potential of steel slag for the treatment of acid mine drainage

Mining is essential for urban, industrial and technological development, however poorly managed mining projects generate negative impacts of great severity on the environment and human health. Some of these impacts include acid mine drainage. There are a large number of physical and chemical methods for the treatment of acid mine drainage, but current trends show a greater efficiency of passive treatments, in particular those including natural or waste alkaline materials. This paper analyzes the alkalinization potential of two types of steel slag, historically considered a waste material from the metallurgical industry. The slags were analyzed to identify their chemical composition and verify that it had not been altered by environmental exposure, they were observed microscopically and their ability to neutralize acidic solutions was measured. Obtained results show great variability on the chemical composition of the slags. The studies show an alkalinization capacity of 15 H+ equiv/kg of basic oxygen converter slag and 5 H+ equiv/kg of blast furnace slag. In addition, blast furnace slags present higher hydraulicity and larger size than basic oxygen converter slags. These results demon-strate the high potential of these by-products as acid mine drainage neutralizers.