Idle time in the washing and iron concentration in leachate removed: two basic parameters in the desulphurization of coal in a packed column

Column biodesulphurization of coal is at the experimental stage and is infl uenced by many variables including temperature, pH, particle size, concentr ation of iron in solution, among others. Idle time in the washing process a nd the concentration of dissolved iron in the purged leachate are two varia bles with a definite effect on the yield of the desulphurization system. In the laboratory, several trials were run with columns packed with coal for different idle times: 1, 2, 3, 5, 6 and 7 days, and for different concentra tions of iron in the purged leachate: 500 to 4,000 mg/l. The optimal values for the two variables; that is, those allowing for the highest desulphuriz ation yields, were idle times of 3 and 5 days, which give an elimination of 56% and 49% of pyritic sulphur, respectively, and 3,000 mg/l of iron conce ntration in the purged leachate, giving a decrease in pyritic sulphur in co al of 57%.