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A large compost pile can spontaneously combust if improperly managed. Spontaneous combustion or spontaneous ignition is a type of combustion which occurs by self-heating (increase in temperature due to exothermic internal reactions), followed by thermal runaway (self heating which rapidly accelerates to high temperatures) and finally, autoignition. [1]
Coal dust suspended in air is explosive—coal dust has far more surface area per unit weight than lumps of coal, and is more susceptible to spontaneous combustion. However, five elements are needed for an explosion to occur: oxygen, an ignition source, coal dust, dispersion of the coal dust, and confinement of the dust. [4]
This "spoil tip" at the Ronchamp coal mines is colored red due to combustion. In some spoil tips, the waste resulting from industries such as coal or oil shale production can contain a relatively high proportion of hydrocarbons or coal dust. Spontaneous subterranean combustion may result, which can be followed by surface fires. In some coal ...
Spontaneous combustion is caused when coal oxidizes and airflow is insufficient to dissipate heat; this more commonly occurs in stockpiles and waste piles, rarely in bedded coal underground. Where coal fires occur, there is attendant air pollution from emission of smoke and noxious fumes into the atmosphere.
The rank of coal is correlated with its geologic history, as described in Hilt's law. In the ASTM system, any coal with more than 69% fixed carbon is classified by its content of carbon and volatiles. Coal with less than 69% fixed carbon is classified by its heating value. Volatiles and carbon are on a dry mineral free base; heating value is ...
Photomicrograph made with a scanning electron microscope and back-scatter detector: cross section of fly ash particles. Fly ash, flue ash, coal ash, or pulverised fuel ash (in the UK)—plurale tantum: coal combustion residuals (CCRs)—is a coal combustion product that is composed of the particulates that are driven out of coal-fired boilers together with the flue gases.
Typically, this method is used to determine water content levels, carbon levels, amount of organic matter levels, amount of volatile compounds. [6] LOI is also used in the cement industry which operates the furnace in the 950 °C range (e.g. cement kilns), combustion engineers also use LOI but at temperatures lower than 950 °C range. [7]
The burning of a solid material may appear to lose weight if the mass of combustion gases (such as carbon dioxide and water vapor) are not taken into account. The original mass of flammable material and the mass of the oxygen consumed (typically from the surrounding air) equals the mass of the flame products (ash, water, carbon dioxide, and ...