Weathering of Fly Ash

Abstract

A CONSIDERABLE body of information is now available regarding the minerals present in fresh fly ash which are available to plants^1,2. During combustion of the coal, adventitious clay minerals such as kaolinite are broken down, and a material is produced containing all the mineral constituents of coal, but with a very low cation exchange capacity (3 m.equiv. per 100 gm.). Many metal oxides are embedded in the glassy phase of the fly ash and may be released slowly over a period of time. In considering the possibilities of establishing crops or plant cover on fly ash deposits, it seemed worth while, therefore, to obtain information on the rate of change of selected constituents. Of particular interest were the elements, for example, boron and aluminium, that are present in quantities likely to be injurious to plants. In the studies to be briefly described here determinations were also made of phosphorus, potassium, calcium and iron in order to obtain any information regarding any likely change in fertilizer requirements as the age of the ash increases.