Introduction
Coking is a type of industrial refining process first developed by American chemist James Cummings and made popular by German industrial chemist Hans Bacht. Converting raw coal into coke is an energy-intensive process that eventually yields a product used in manufacturing steel as well as other industrial products. The process of coke production begins by treating raw coal with heat energy to reduce its moisture content. Heat treatment is then continued until the carbon content of the coal has been converted into a partially solid material called coke. Generally, the higher the temperature and the longer the coal is heated, the greater the potential yield of coke.
The Production Process
The converting of the raw coal into coke is a complex process that requires adequate knowledge and experience. A mixture of coal and recycled materials, such as fly ash, is fed into a coke chamber, where it is heated to a temperature of over 500 °C (900 °F). As the coke is subjected to the extreme temperatures of the coke furnace, the coal particles fuse together and some of the volatile fuel components are released and evaporated. This produces a coke oven gas which can be used for other industrial processes.
The carbonization of the coal/fly ash mixture converts the mixture into a partially solid material known as coke breeze. This product is referred to as green coke and is composed of over 90% fixed carbon. Subsequently, green coke is subjected to a further calcination process, which is designed to reduce the moisture content and remove some of the volatile materials such as tar and ammonia.
The final product is a semi-solid material composed mostly of carbon and is referred to as calcined coke. Calcined coke must have a low sulfur and phosphorus content in order to be suitable for use in the steel-making industry and other industrial processes.
Uses
The primary use for coke is in steel production, as an essential component in blast furnaces. In the steel-making process, coke is used as a fuel and a reducing agent, and is eventually transformed into pig iron, with a typical composition of about 90% iron and 3-4% carbon. Coke can also be used as a fuel source for other industrial processes, such as the manufacture of chemicals or minerals.
Conclusion
Coking is an essential industrial process that converts raw coal into coke, a fuel and a reducing agent used primarily in the steel-making industry. Utilizing strict quality control processes, coke producers are able to produce a semi-solid material composed mostly of carbon that is suitable for use in the steel-making and other industries. The production of coke is an energy-intensive process that requires adequate knowledge and a strict adherence to quality control procedures.
