EIACP (PC-RP) on Environmental Problems of Mining

UTILIZATION OF FLY ASH FOR TREATMENT OF ACID MINE WATER

Alka Pradhan and Jitendra P. Deshmukh*

Motilal Vigyan Mahavidyalaya, Bhopal (INDIA)

                                    Received November 14, 2007                                          Accepted August 4, 2008

ABSTRACT

Lignite and coal are widely used in all thermal power plants and industrial processes such as boilers, furnaces etc. Both coal and lignite occurs naturally in the lithosphere and mining is carried out to extract the lignite and coal. Most of the power plants are situated either near to the mine or they have their own captive mine. There are several environmental problems associated with the opencast mining of lignite ranging from air, water and noise pollution and land degradation. The most important among the above is formation of acid mine water also known as acid mine drainage (AMD) due to the presence of pyrite in the lignite/coal. On the other hand lignite and coal consuming power plant generates Fly Ash (FA) which is a hazardous waste and needs safe disposal. There are several methods for treatment of acid mine water eg. using calcium carbonate, sodium hydroxide, sodium bicarbonate or anhydrous ammonia. These chemicals raise the pH to acceptable levels and decrease the solubility of dissolved metals but the cost of the treatment of acid mine water is very high as the acid mine water generated is of the order of 300 Kl/Day for 2,000 tones/ day or less production capacity mines. In this research work authors have tried to develop treatment method of acid mine water using fly ash. The fly ash contains alkalinity in the form of CaO and the treatment cost can be curtailed as the fly ash is a waste and it also requires safe disposal and hence needs additional cost. It is observed that fly ash containing CaO in the range of 10 -12 % can neutralize the acid mine water of pH 2.5 in 30 minutes of reaction time. For better understanding topics covered are chemistry, treatment methods, characteristics of acid mine water and fly ash and experimental procedure etc.

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