EFFECTS OF TREATMENTS ON THE MINERAL MATTER AND ACIDIC FUNCTIONAL-GROUP CONTENTS OF TURKISH LIGNITES

Six Turkish lignites were treated with solutions of HCl or EtONa at am bient temperature or at 150 degrees C. The proximate analysis, forms o f sulfur, acidic functional groups and calcium contents of the raw and treated lignites were determined. The solutions after treatment were analysed for calcium. The effects of the treatment on certain structur al components of the lignites varied from one lignitie to another. HCl treatment was effective in ash reduction and in the transformation of carboxylate species to carboxylic acids, but not in desulfurization. The ash reduction was accompanied by an increase in combustible sulfur . EtONa treatment was effective in desulfurization but not in ash redu ction or in the removal of chelate- or salt-forming cations. The resul ts suggested that this treatment promoted selective cleavage of certai n chemical bonds, such as ester, ether or carbon-sulfur bonds, resulti ng in an increase in acidic functional groups of the lignites, desulfu rization and partial dissolution FT-i.r. spectroscopy and X-ray diffra ctometry provided some additional evidence regarding the changes in li gnite structure due to the treatments.