Chapter 17 - Conclusions

Abstract

This chapter discusses the developments in chemical cleaning of coal. Chemical cleaning of coal has the potential advantage of removing both inorganic and organic sulfur. Such processes are still at the research stage. Many rely on oxidation or reduction of sulfur in coal. The problem is to treat selectively the sulfur. Conditions under which significant quantities of sulfur are removed also lead to degradation of the coal. Much more fundamental research is required to determine the occurrence and nature of sulfur forms in coal and their reaction under possible desulfurization conditions. Microbiological desulfurization of coal is, at present, of only academic interest. Reaction times are of the order of several days. To process sufficient coal for a power plant would require a prohibitively large storage volume. The potential for absorption of SO 2 by a sorbent during the fluidized bed combustion of coal is widely known as one of the advantages of this combustion technique. It is found that by removing the sulfur in the form of SO 2 , the technique is not dependent on the form or chemical nature of sulfur in coal. Reductions in SO 2 emissions of greater than 90% can be achieved for most coals.