Coal Desulfurization and Deashing by Oil Agglomeration

Abstract

Coal organic matter was separated from its associated mineral matter by reducing the material to a fine-size, suspending the particles in water, selectively agglomerating with oil the particles which were largely organic, and screening the suspension to recover the agglomerates. Since particles of iron pyrites tended to be agglomerated with the coal, various means of preventing the agglomeration of pyrite were investigated. In some cases pyrite agglomeration was prevented by suspending the particles in an alkaline solution. In other cases it was prevented by pretreating the particles with a warm alkaline suspension through which air was bubbled to oxidize the surface of the pyrite. However, when this method of pretreatment was applied to several Pennsylvania coals, a considerable part of the pyritic sulfur was extracted through dissolution. An unexpected discovery revealed by scanning electron microscopy was the unusual stability of the coal microagglomerates which remained after the oil was extracted.