Oil Agglomeration of Coal in Inorganic Salt Solutions

Abstract

Coal fines were suspended in water or in salt solutions for agglomeration with either heptane or paraffin oil. Coal recovery with a limited amount of oil was found to increase markedly as the salt concentration was raised. The increase in recovery appeared due to compression of the electrical double layer surrounding individual coal particles and oil droplets. The recovery was observed to depend on the pH of the suspension with the greatest recovery occurring at the isoelectric point. When a mixture of hydrophobic coal particles and kaolin particles was suspended in 1.5 M sodium chloride and agglomerated with paraffin oil at a level of 0.065 goil/gcoal, 95% of the coal was recovered and over 90% of the kaolin was rejected. This recovery was 265% greater than the recovery achieved by suspending the mixture in water and agglomerating it with the same amount of oil. These results show that the use of salt solutions in the oil agglomeration process can result in reduced oil consumption