NON-COKING COAL (NCC)

These are coal of poor coking properties i.e. does not soften and form cake like coking coal during carbonization in the coke oven. Such coals with relatively lower ash and higher fixed carbon are used in metallurgical applications viz. COREX technology based iron (pig iron) plants, Coal based DRI Plant etc, while those with higher ash are normally used in thermal Power Plants as steam coal.

NCCs are classified into A,B,C,D,E and F grades depending upon its heat value which is a fraction of carbon and volatile matter and ash content in the coal.

COKE OVENS/ COKE OVEN BATTERY: Coking Coal is converted into Coke in coke ovens which are silica refractory lined ovens/ chambers. Coke Oven battery comprises of a large number of ovens, 50-70 in tandem. Such batteries are normally attached with By-product plant where in valuable constituents are recovered from the volatile /gaseous content of coal driven out during carbonisation. Accordingly, such coke ovens are known as By-product coke oven battery vis-a-vis Non-recovery type coke ovens, also known as Bee-hive type coke ovens.

COKING TIME: Coking time is defined as the time required for conversion of coal to coke in the coke oven which varies in the range of 1520 hrs.

YIELD OF DIFFERENT VARIETIES OF COKE: Typical yield from one tonne of dry coal charge to coke is 75%. Depending upon size ranges, coke is classified into the following categories :-

Category	Yield	Use
BF Coke (25/40-80mm)	85%	Blast Furnace
Nut Coke (15-25mm)	5%	Sinter Plant /Ferro Alloy/Pig Iron Industry
Coke breeze (0-15mm)	10%	Sinter Plant /Cement Industry

Coal Dust Injection (CDI)/ Pulverised Coal Injection (PCI) : These are technologies wherein pulverised/ granulated/ dust coal is injected into the blast furnace through the tuyers along with the Blast to replace part of the coke requirement.