Course of development of fine coal flotation process in China

Flotation process and process equipment are two core elements that form up a flotation system and determine both product quality and flotation efficiency. On the other hand, the capacity and performance of equipment, flotability of feed coal and required ash value of concentrate are important influencing factors in determination of flotation process. Along with the equipment becoming increasingly larger in size and higher in efficiency changes of coal property and market demands as well as rigid constraint of environmental protection policies, the flotation technology has seen many changes in the course of its development, such shifting from the use of thickened slurry flotation process to direct flotation process, dislimed / sized coal flotation process and to two-stage / multistage flotation process. The development of large-size flotation machines provides a basis for the use of direct flotation process to treat coal slurry water and tacking the difficulties in flotation of thickened pulp caused by accumulation of fine slime. It is noted that the use of primary flotation process can generally meet the requirements in flotation of easy-to-float coal; the one roughing + one cleaning process is generally suited to treating difficult-to-float coal with a high proportion of fine slime; with the use of one roughing + one scavenging + two / three cleaning process for treating extremely hard-to-float coal containing a high proportion of intermediate-density materials, the up-to-standard concentrate, middling and tailing products can also be obtained; and for treating the coal which has gone through sufficient liberation, the multistage closed-circuit process in higher in efficiency compared with the open-circuit one.