The researchers conducted an experiment to clean coal from Pakistan, which has a lot of minerals like pyrite that make it hard to use. They found that using a specific gravity method and a certain particle size helped separate the clean coal. The best results were achieved with a 60 mesh particle size, and the clean coal yield was 86.1%. After 16 hours, the separation process didn't change much. The ash content of the clean coal was reduced from 36.38% to 11.1%, making it suitable for industrial use.