Explanation: In the process of carbonisation, the bituminous coal is slowly heated to remove moisture and occluded gases. Then at 270oC H2S and olefin gases are evolved. At about 450oC the liberated gases consist of hydrocarbons and at 700oC hydrogen gas is liberated.

Explanation: If the coal is free to expand at plastic stage, it produces a highly swollen open texture coke produced from strongly coking coal. If this expansion is suppressed by the retaining wall, a dense coke having fine pore structure is produced.

Explanation: Coal contains maximum carbon inside it which is not a good conductor of electricity (except graphite). Coal produces a large amount of heat on its combustion but is not a conductor of heat.

Explanation: The plastic zone so formed by the caking coal results in a considerable temperature gradient. There may be a drop of about 250 oC across half an inch thickness.

Explanation: Caking coal form a plastic zone which acts as a heat barrier. Non-caking coal does not forms this plastic material due to which it has high rates of carbonisation. Coking coals are formed by caking coals.

Explanation: Coke-ovens are used for the completion of process of carbonisation. The final product obtained by carbonisation is coke. Destructive distillation plants are used to generate charcoals.

Explanation: The temperature in this type of carbonisation varies from 700-900 oC. The yields of NH3, tar, light oils are obtained from this carbonisation. The yields of tar obtained from this process are different from the yields obtained by high temperature carbonisation.

Explanation: By pulverising the coal, the rate of combustion of coal can be easily controlled which helps in the easy formation of coke. Coal can also be briquetted for using under friable condition.

Explanation: The coke produced by this method is used as a domestic fuel. The coke formed contains 5 to 15 % of volatile matter and is not sufficiently strong for metallurgical processes.

Explanation: The by-product gas produced in this process is about 370-480 m3/tonne. Gas coke is produced at the gas works of cities. The calorific value of the coke obtained is less than that of the coke obtained by low temperature carbonisation process.