REACTIVITY OF LIME AND RELATED MATERIALS WITH SULPHUR DIOXIDE

Abstract

A study has been made of reactions between some alkaline earth metal compounds and sulphur dioxide. The compounds studied included naturally-occurring forms, limestone and dolomite, and industrial products, Limbux and quick-lime. Particular attention was paid to reactions which could have proved useful in the desulphurisation of industrial flue gases. All the substances used reacted to some extent with sulphur dioxide, but often slowly. The greatest reactivity was shown by calcium-based compounds as the carbonate or hydroxide decomposed to form fresh, highly active calcium oxide. Reaction rates, below 400°C, were only appreciable for calcium oxide. The reaction products, depending upon conditions, included sulphites, sulphates, sulphides and oxides. At lower temperatures, sulphite was formed and the thermal stabilities of the alkaline earth metal sulphites were studied in greater detail.