Abstarct: Coal is one of the most important energy sources which is used in production of coke. But presence of sulfur and ash in coal as impurities affect its quality and leads to environmental pollution. Thus in this thesis, effective parameters to reduce the sulfur content of East-Alborz coal concentrate using leaching methods were investigated in order to maximize the removal of sulfur. To access this purpose, initial leaching tests were performed using different leaching agents and between these agents, nitric acid had high potential to reduce sulfur. Evaluation of effective factors on sulfur reduction using design of experiments software and response surface method (RSM), indicated increase of acid concentration, temperature and reaction time are the most important factors in reducing sulfur. The results showed most of total sulfur reduction (87%) is obtained as: acid concentration 30%, temperature 80 C and 88 minutes. Also, reduction of ash from coal was studied by nitric acid and evaluating parameters is determined by reducing time and increasing temperature and acid concentration, ash removal rate increases and reaches about 30%. Finally, in order to study the kinetic of pyritic sulfur dissolution in nitric acid, shrinking core model was fitted to the experimental data. The results showed the dissolution rate of pyritic sulfur is controlled by surface chemical reaction.