The Acid Mine Drainage (AMD) is the result of the natural oxidation of sulphide minerals when exposed to the combined action of water and oxygen. One of the technologies to prevent the AMD consists in the alkaline additive method. Thus, the aim of this work was to study, at laboratory scale, the DAM control by blending coal waste with a metallurgical slag. A coal-tailing sample was collected from a coal mine and the slag was obtained from a semi-integrated steel plant, both located in Rio Grande do Sul State, Brazil. Static tests were carried out by the acid-base account method to determine the balance between the acid producing and acid consuming (neutralizing) mineral components of the sample. Later, kinetic tests were conducted in humidity cells, following the ASTM D 5744-96 method. The results showed that the coal tailing generates DAM. However, the environmental problems can be minimized mixing the coal waste with the metallurgical slag in a 4,8:1 proportion. The kinetic experiments proved that, in this condition, the lixiviate presents a higher pH and lower concentration of acidity, metals and sulphate. Finally, it is possible to conclude the blending slag in coal tailing deposits can be a viable alternative for DAM control in coal mining.
Acid drainage of mine; slag; alkaline additives
