Determination of total fluorine in coal by the combustion-hydrolysis/fluoride-ion selective electrode method

Abstract

A rapid analytical method has been developed for the determination of fluorine in coal. Coal is mixed with quartz sand, then burnt and hydrolysed in steam and oxygen at 1100 °C, whereupon the different forms of fluoride in coal become solubilized. The fluorine is determined with a fluoride-ion selective electrode. The method proposed is not affected by the ash content of the coal. The obtained solution has a simple ion composition and a low blank value giving the method potential as a fluorine determination technique. A series of typical coals have been tested and the agreement between the proposed method and the ASTM method and alkali-fusion method is satisfactory. Two sedimentary rock standards have been analysed and the results are within permissible limits of error. The method is considered to be accurate and reliable, and is first compared with the half-fusion method.