Coal and coke is ground to a fine powder prior to being blown into the kiln. The large quantities of these fuels purchased and stockpiled at a cement plant result in a very uniform feed. Liquids are accumulated in large batch tanks which are continuously agitated. Depending on feed rates and tank sizes, batches will last ten hours or more. Other fuels are accumulated and fed in large enough quantities to maintain uniform feedstream characteristics just as with the coal and coke.
Process outputs other than emissions include cement clinker and cement kiln dust.
Cement clinker by virtue of its product quality requirements is a uniform process output. Cement kiln dust is similarly uniform. Changes in process outputs that may occur as a result of sudden input changes, metal spiking as an example, typically take four to ten hours to have full effect. The large residence time for materials in the kiln combined with internal recirculating loads will necessarily result in any changes occurring over a number of hours. All samples were taken on an hourly basis.