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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]
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.
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]
Stockpiles will also be used between the plant and the discard dump stackers. The plant will use dry screening to avoid having to pump tailings to tailings dams. [12] The waste material from the Grootegeluk mine, particularly from the lower levels, is prone to spontaneous combustion.
The autoignition temperature or self-ignition temperature, often called spontaneous ignition temperature or minimum ignition temperature (or shortly ignition temperature) and formerly also known as kindling point, of a substance is the lowest temperature at which it spontaneously ignites in a normal atmosphere without an external source of ignition, such as a flame or spark. [1]
Coal Industry Stock Outlook: Going to Get Tougher Ahead
Larger coal stockpiles have a reduced rate of heat loss, leading to a higher risk of spontaneous combustion. Travelling, luffing boom stackers that straddle a feed conveyor are commonly used to create coal stockpiles. Tunnel conveyors can be fed by a continuous slot hopper or bunker beneath the stockpile to reclaim material.
The FDA has banned red dye No. 3, as the synthetic additive is known to cause cancer. Nutritionists Ilana Muhlstein and Robin DeCicco discuss what this means for American health.