Met coke – The Methods of Processing
There are only two proven and sure processes of manufacturing the hard coke, also known as metallurgical coke or Met coke. One is called the “by-product process” and the other one is the “beehive process”. Both processes were used in American coking industry in the early part of the twentieth century. Over the years the by-product process won the competition and the beehive process has been superseded. Formerly small quantities of air were admitted to the coking chamber to facilitate the burning of all the volatile products released from the coal. The combustion of the volatiles generated much heat which was used to bring about the coal further decomposition. The beehive process was much inefficient because of lack of the provision of recovering products other than coke. In the by-product process the coal decomposition takes place without the air access and all the heat needed to coking is furnished indirectly. In this process many valuable by-products (like tar, coke-oven gas and light oil) are recovered.
At present, the Met coke produces in US is produced almost exclusively by the by-product method. The by-products ovens have the form of narrow, long chambers made of silica-bricks and being heated by means of fuel gas externally. The fuel gas combustion takes place in the built-in flues, located in the brick walls of refractory separating all the coking chambers one from each other.