Oxidation and Rank

It is generally (bnt no totally) accepted that the mechanism of the oxidation of coal takes place in five steps, each one chemically dependent npon the temperature (Barkley, 1942 Parry, 1942 Roll, 1963)  

The coal begins to oxidize slowly until a temperature of approximately 50°C (122°F) is reached. 

At this point, the oxidation reaction increases at an increasing rate until the temperature of the coal is approximately 100°C-140°C (212°F-285°F). 

At approximately 140°C (285°F), carbon dioxide and water vapor are produced and expelled from the coal. 

Carbon dioxide liberation increases rapidly until a temperature of230 C (445°F) is reached, at which stage spontaneous ignition may occur and spontaneous combustion may take place. 

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