The behaviour of sulphur, during rapid carbonisation of high-organic-sulphur New Zealand coals

Abstract

Factors relating to the release of sulphur during slow and rapid carbonisation of coals are reviewed in detail. Experiments are described in which three high-organic-sulphur coals were carbonised in fluid bed and disperse phase equipment. A linear relationship was found to exist between losses of weight and total sulphur. Attempts were made to describe devolatilisation in terms of reaction kinetics, but with no real success; rate-controlling steps are evidently of a physical, rather than a chemical nature. Hydrogenation for short periods was effective in lowering the sulphur content of chars, without appreciably affecting the yield. Analysis of the volatile products showed that most of the volatilised sulphur is present as mercaptans or high-molecular-weight tarry compounds.