GEOCHEMISTRY OF ARSENIC AND ANTIMONY IN THAR COAL

Abstract

Thar coal is the largest coalfield of Pakistan, having 185 million tons of proven reserves. Thar coal have been analyzed for As and Sb and their environmental impact is assessed. Arsenic and antimony in coal belongs to iron sulphide association. The results show that in coal antimony (Sb) accumulates stronger than arsenic (As). Among all three blocks of Thar coalfield antimony ranges from 1.3 ppm to 3.2 ppm in Block-I; in Block-II, the concentration of Sb ranges from 1.3ppm to 3.7ppm; and in Block-III, it ranges from 1.4 ppm to 4.3 ppm. The concentration of arsenic in Block-I varies from 0.9 to 2.1ppm; in Block-II, it ranges from 0.8 to 2.7 ppm and in Block-III of Thar coalfield As ranges from 1.9 to 4.2 ppm. In Thar coal, the probable source of arsenic and antimony is either hydrothermal solutions or the organic matter or pyrite present in coal. Long-term exposure to antimony causes various health problems including respiratory effects. Exposure to arsenic may cause arsenicosis. It is therefore suggested that arsenic and antimony from Thar coal may be removed by sequential leaching process.