Answer: Removing impurities such as ash, sulfur, and rock from coal
Notes: Coal washing or coal beneficiation is a process to remove impurities like ash, sulfur, and rock from raw coal. This is achieved through mechanical or chemical separation techniques such as dense medium separation, froth flotation, or gravity separation. The process increases the quality of coal by reducing ash content and sulfur, commonly removing 50%-80% ash and 30%-40% total sulfur.
