Heavy Metals from Acid Mine Drainage in Coal Mines-A Case Study

Acid drainage is most common problem or associated with almost all mines containing sulphide deposits and coal containing high pyrite. Acid drainage is caused when rain water and or seepage from rock formation interact with sulphur bearing minerals. It produces water of high acidity with higher metal concentration. Acid drainage is most susceptible to dissolve heavy metals particularly Iron, Zinc, Copper, Lead Mercury etc. The case study of surface coal mines of Northern Coal Fields Ltd., Singrauli is presented in this paper. Various techniques for decreasing the acidity of water in coal mine were experimented at laboratory scale. The pH value is ranging from more than 2.66 to 3.91.The ions and others content are also significantly higher than recommended permissible limit. There is waste water effluent treatments plant for arresting TSS in effluents coming from workshop. The marginal acidity in sump water is a major issue as for as water quality threat is concerned. The technique suggested in fields’ application and effective to lower the pH value and others constituents present in water. It has been concluded that along with decrease in pH value, the concentration of iron is lowered significantly. However, the deposition of iron precipitates on surface rocks decreases the neutralizing capacity of rocks overburden used as acid neutralizer. The technique suggested for acid water treatment is field applicable and along with acidity it decreases the iron content of water of coal mine also.