Removal of Sulfur and Ash from Coal Using Molten Caustic Leaching, a Case Study from Hazro Fields, Turkey

Abstract

Molten caustic leaching process is effective in reducing significant amount of ash derived from minerals, pyritic sulfur, and organic sulfur from coal. The effect of leaching coal samples from Hazro fields, situated in Southeast Anatolia region of Turkey with molten sodium hydroxide as well as followed by mild acid on demineralization and desulfurization was investigated. The effects of alkali/coal ratio, time, and temperature on the leaching efficiency were detailed and the experimental results are presented here. Chemical demineralization and desulfurization of coal samples using molten sodium hydroxide was investigated in the temperature range of 200−400°C. The percentage of demineralization and desulfurization increased with the increase in alkali/coal ratio. The removal of total sulfur and ash increases with increasing leaching temperature and time. As a result of MCL, ash content of Hazro coal was reduced from 18.31 to 6.77 %, and 70% of combustible was recovered. Total sulfur and volatile matter content was reduced from 7.54 to 1.01% and from 47.80 to 12.41%, respectively. Most of the inorganic sulfur and a significant portion of the organic sulfur were removed.