Reverse flotation of coal can be explained as a process where valuable minerals are depressed, while undesired and unhealthy minerals are floated with the help of some reagents. Nowadays, conventional enrichment method of coal could not achieve removing unhealthy minerals partially from internal structure of coal such as sulfur, Hg, Au, which propagate in air after burning treatment, or heavy metals such as Be, Cr, Ni, As, Cd, Co, Ni, Sb, Se, Pb, Co, Cl, Be, Ba, which involve in water and soil where habitat and human health can directly be influenced from them. In fact, reverse flotation of coal enables to remove these undesired mineral content from coal structure not only in macro size but also in micro size. On the other hand, like undesired minerals, valuable ones like vanadium, germanium, etc. are also taken from coal particles by using the same procedure. Thus, with all these respect, reverse flotation is considered as an alternative and innovative solution for coal beneficiation especially for low rank coal since low rank coal is more compatible for reverse flotation because of being more hydrophilic which means tendency to float is less. Around the world wide, most of the coal reserves belong to low rank coal, so application of reverse flotation is becoming more inevitably common in future.
Part of the book: Energy Systems and Environment