Development, testing and plant trails of single reagent system for coal flotation

Abstract

Flotation is an important means of upgrading the fine fraction of raw coal, typically particles finer than 0.5 mm. Due to increased use of highly mechanized mining techniques large quantities of fines (< 0.5 mm) are being generated. These fines presently account for approximately 20–30% of the total plant feed. More than 140 million tones of fine coals are beneficiated by flotation worldwide annually. In coal flotation, reagents are required to enhance the hydrophobicity of coal surface. In addition to hydrophobic character, the selectivity, proper froth structure, stability and less sensitive to water chemistry are important. Water insoluble hydrocarbons are widely used as collectors in coal flotation. These collectors are basically non-polar oils like diesel, kerosene, etc. along with some frothers. Thus, it is necessary to add collector and frother separately in coal flotation. It is generally accepted that in coal flotation a single reagent system is more advantageous than the present practice of two reagent system. National Metallurgical Laboratory is involved in the flotation of coal fines using alternative single collector systems to developed specially replace fuel oils and frothers. For this purpose NML has entered into an agreement with M/s Somu Organo-Chem Pvt. Ltd. (SOCPL) Bangalore, a leading reagent manufacturer. Under this collaboration M/s SOCPL developed reagents and NML evaluated their selectivity index and application in coal flotation. Among many reagents developed and evaluated one best reagent was selected and full scale plant trails were conducted. The paper deals with the results obtained with several reagents in the laboratory and the plant trails.