There is a shortage of coking coal used in steel plants and some part of their requirement is met by the companies from imported coking coal. Steel plants require low ash content of coal for their sustainability with respect to techno-economics as well as environmental aspects.
The overall availability of coking coal from indigenous sources is inadequate to meet the requirement of steel plants. The ash content in unwashed indigenous coking coal is typically in the range of 22-35% whereas technological requirement of ash content in coking coal for use in steel plants is normally about 10-12%.
High ash indigenous coking coal is washed in coal washeries to reduce ash content. Even after washing, indigenous coking coal typically contains about 18-20% ash.