A study on the washability of the Azad Kashmir (Pakistan) coalfield

Pre-combustion coal cleaning is one of the most effective methods for removing unwanted minerals and pollutants. Coals are cleaned at the mine site using water-based processes to remove non-combustible minerals and to lower the concentration of pollutants such as sulfur. This paper summarizes the washability study conducted under the coal quality evaluation and beneficiation project of Azad Kashmir (Pakistan) coalfield. The aim of the study was to investigate and interpret washability characteristics of Kotli coalfields. Washability parameters such as degree of washing and washability number were also calculated and compared. The coal samples of Kashmir coalfield belong to lignite (LigB) to high volatile bituminous (hvCb) category on the basis of proximate and gross calorific value analysis containing 8.80 to 85.2% ash, 4.70 to 85.7% fixed carbon and 4.63 to 34.3%, volatile matter. The majority of coal samples under investigation were found amenable to washing using gravity separation. As a result of present investigation 21.6, 22.4, 9.0, 52.1 and 42.3% of ash in the raw coal could be reduced to 7.7, 9.2, 4.8, 5.4 and 10.0% cumulative ash for the five samples. The optimum grade recovery conditions are also discussed in this paper.

► Low-rank coal samples were investigated for washability studies.
► Majority of the samples under investigation with relatively low disintegration in water were found amenable to washing using dense media separation.
► The results showed the size reduction has significant influence for the specific gravity Vs clean coal yield relationship.