When coal is crushed into smaller pieces, it increases the amount of clean coal that can be separated from impurities during testing. By reducing the size of coal samples, the yield of clean coal can go up significantly. Large coal samples lead to lower clean coal yield. For coal samples larger than 50 mm, the clean coal yield is much better when the coal is crushed into smaller sizes. The difference in clean coal yield between large and small coal samples impacts the plant's costs significantly. Proper testing of coal samples is crucial for accurate results in determining the quality of clean coal that can be produced, which is important for the plant's efficiency and financial well-being.