On-Stream Ash in Coal Monitoring for Profit

When coal is irradiated by the X-rays emitted from a plutonium 238 isotope, the radiation absorbed by elements of low atomic number (carbon and hydrogen) is lower than that absorbed by elements of high atomic number (silicon, aluminium, iron) which form the ash in coal. The differences are reproducible and readily measurable, and this paper describes how this technique is used to determine the ash content of coal and to optimize measurement accuracy. Uses of the output signal are given with an example of a simple control circuit, and the advantages of instantaneous ash measurement are highlighted in terms of operational convenience and profit.