Manufacture of Formed Coke by Hot-Briquetting Method (II)

Abstract

In order to develop a new process to make metallurgical coke from the blends mainly composed of non-or slightly caking, high volatile coals, hot briquetting followed by corbonisation has been carried out on a pilot scale.This paper deals with the carbonisation of hot briquettes, of which manufacture was reported previously and given here some additional explanations.The preliminary small scale tests on carbonising briquettes to seek the suitable conditions for obtaining hard fomed coke showed that the hot briquettes should be: 1) 24-32 per cent in volatile matter, 2) charged immediately into the oven without being cooled, 3) carbonised as slow as possible, until the temperature reaches about 600-700°C.Based on these results, a pilot carboniser of travelling grate type with a capacity of 100kg/hr was constructed. The hot briquettes were carbonised to about 600-700°C in 1.5-2hr on the travelling grate, which is made of mild steel and 600mm wide, 3, 000mm long. Then, semi-carbonised briquettes were turned into the high temperature chamber, where they were rapidly carbonised to about 900°C. Heat required is supplied by combustion of the gas evolved from the briquettes.The resulting formed coke has the drum index of 80% which is lower by 10% than that obtained by a small scale test.