Studies on the Manufacture of Formed Coke for Blast Furnace

Abstract

At the Government Industrial Development Laboratory, Hokkaido, the process consisting of low-temperature carbonisation and hot briquetting followed by high temperature carbonisation is being investigated to convert non-or slightly caking coals into metallurgical coke and also to develop a continuous coke-making process. It is based on the technique for making solid smokeless fuel reported previously.This paper relates to low-temperature carbonisation and hot briquetting carried out with a pilot plant of 250kg/hr.Coking coals blended with 30 to 50 per cent of slightly caking coals of 1 to 11/2 in free swelling index are crushed and carbonized at 410-450°C in a fluidized bed carbonizer provided with a stirrer. Hot fine coals are formed while still hot by a double roll press.At first air was used as a fluidizing gas and then it was replaced by hot inert gas. Bed temperature was controlled within ±5°C by means of automatic feed control. In this way, briquet coke high in strength became obtainable.Secondly, a pre-heater of fluidized bed was added in series before the carbonizer. Though the effects of shortening of residence time in the carbonizer on coke quality were little recognized, the capacity of the carbonizer was much increased. From these results, a compound fluidized carbonizer was proposed.As regards high temperature carbonisation, a fluidized medium carbonizer of horizontal type is still in the stage of laboratory scale, experimental results being briefly described.