The mode of occurrence and origin of chlorine in Puertollano coals (Spain)

Chlorine distribution in vitrain, clarain and associated sediments from Puertollano has been studied. From the study of relationship between chlorine content, rank, petrographic and geochemical characteristics, an association of chlorine with the organic fraction of coal has been inferred. Vitrains have a higher chlorine concentration than clarains, which could be related with their microporous structure, where water has easy access. Chlorine is introduced into these coals by percolating surface water, after which it is ionically linked to coal components. The tonstein intercalated between the coal seams may be the source of chlorine compounds. In addition to the chlorine bonded to organic matter, the presence of low proportions of sodium or potassium chlorides in the mineral matter, or in solution in water, cannot be totally discarded for some samples. (C) 1999 Elsevier Science Ltd. All rights reserved.