The article discusses how to improve the quality of coal used in clean technologies. By re-preparing coal using two jig systems, the researchers were able to create better quality coal concentrate with less ash. This means that more valuable coal can be produced efficiently. Using secondary preparation in the jigs helps to get rid of incorrect particles, leading to a more effective separation process. With this method, it's possible to achieve lower ash content in the final coal concentrate compared to using just one jig. The study shows that using multiple jigs in coal preparation plants can significantly increase the overall production value, particularly when aiming for high-quality coal concentrate with low ash content.