Carbonization of Coal for Metallurgical Coke Production Nov15

Carbonization of Coal for Metallurgical Coke Production...

Carbonization of Coal for Metallurgical Coke Production Carbonization of coal is also known as coking of coal. The process consists of thermal decomposition of coals either in the absence of air or in controlled atmosphere to produce a carbonaceous residue known as coke. Carbonization of coal can be carried out at the following three temperature ranges. Low temperature carbonization is normally carried out in the temperature range of 500 deg C to 700 deg C. In this type of carbonization, the yields of liquid products are higher and there is lower gaseous product yield. The coke produced is having higher volatile matter and is free burning. Medium temperature carbonization is done at temperature range of around 800 deg C. This carbonization produces smokeless soft coke. By products produced are similar in characteristics to high temperature carbonization. Medium temperature carbonization is rarely practiced these days. High temperature carbonization is carried out at a temperature which is above 900 deg C. This carbonization gives higher yield of gaseous products and lower yield of liquid products. This carbonization produces hard coke and is normally employed for the production of metallurgical coke from coking coals. Process of carbonization of coal The coal to coke transformation takes place as the coal is heated. When the state of fusing is reached, the layer of heated coal softens and fuses. From about 375 deg C to 475 deg C, the coal decomposes to form plastic layer.  Destructive distillation reactions proceed rapidly in the plastic layer with evolution of volatile products. At about 475 deg C to 600 deg C, there is a marked evolution of tar, and aromatic hydrocarbon compounds. The gas and condensable vapour are entrapped in the plastic mass and, as they expand tend to swell it. As the...

Coke making in Byproduct Coke Oven Batteries Jun01

Coke making in Byproduct Coke Oven Batteries...

Coke making in Byproduct Coke Oven Batteries  Coke causes up to 50 % of the costs during the hot metal production. The cost effective production of high quality coke is thus of prime importance for the competitive ability of the iron production. Metallurgical coke is used in iron and steel industry processes (primarily in blast furnaces) to reduce iron ore to iron. Over 90 percent of the total coke production is dedicated to blast furnace operations. Foundry coke comprises most of the balance and is used by foundries in furnaces for melting metal and in the preparation of moulds. Foundry coke production uses a different blend of coking coals, longer coking times, and lower coking temperatures relative to those used for metallurgical coke. Most coke is produced in the world using the byproduct coke oven batteries and most of the coke plants are integrated with iron and steel production facilities. The manufacture of coke by heating coal in absence of air has its origins at the start of industrial revolution when Abraham Darby used it in the smelting of iron ores in 1709 in England. The method of coke production was initially the same as for the production of charcoal, stockpiling coal in round heaps, igniting the piles, and then covering sides with clay. This laid the foundation for beehive coke making. Gradual advances led to the development of beehive, reverberatory and byproducts ovens, culminating into regenerative coke ovens with recovery of the byproducts around a century ago. Coal is converted to coke in large coke oven batteries by the destructive distillation of coal. The coking process consists of heating coal in the absence of air to drive off the volatile compounds. The resulting material is a carbon mass called coke which is a...