§ Mr. Skeetasked the Secretary of State for Energy if he will identify the trace elements in coal, and identify the extent to which they remain within the combustion system or escape into the environment.
§ Mr. EadieTraces of any of the 92 naturally occurring elements are liable to be detected in coal in roughly the same proportions as they occur in the natural environment from which the coal is derived. On combustion most of the gaseous elements, together with chlorine and bromine compounds and mercury, are discharged with the waste gases. The remaining elements form solid compounds which constitute the ash, of which in a modern power station over 99 per cent. is retained in the combustion system. The rest is dispersed with the waste gases as very fine particulate matter. It may contain a slightly enhanced proportion of the more volatile elements such as antimony, arsenic, cadmium, lead, selenium and zinc, but their concentrations are nevertheless very low and the great majority of these and the other solid elements are retained in the ash.