New developments in coal briquetting technology

Briquetting of coal has been with us for well over a century. In the earliest applications of coal briquetting, less valuable fine coal was agglomerated into briquettes using a wide variety of binders, including coal tar, pitch and asphalt. Eventually, roll briquetters came into more widespread use, permitting the process to become a continuous one. Coal briquetting went out of favor during the 1950s in most of the industrialized world. The major reason for this decline in use was the discovery that the coal gas distillates used for binders were harmful to human health. Also, the abundance of cheap petroleum made coal briquettes a less attractive alternative as an industrial or domestic fuel. The re-emergence of coal as a primary industrial fuel and also its increased prominence as a fuel for thermal electric power stations led to a large increase in the annual volume of coal being mined worldwide. Coal preparation technology steadily improved over the years with the general exception of fine coal preparation. The processes available for treating this size range were considerably more expensive per unit mass of coal treated than coarse coal processes. Also, costly dewatering equipment was required after cleaning to remove surface moisture. Evenmore » with dewatering, the high surface area per unit mass of fine coal versus coarse coal resulted in high moisture contents. Therefore, little incentive existed to improve the performance of fine coal processes since this would only increase the amount of wet coal fines which would have to be dealt with. With such an ever-increasing volume of coal fines being created each year, there emerged an interest in recovering this valuable product. Several schemes were developed to recover coal fines discarded in abandoned tailings impoundments by previous operations.« less