In general, it is not recommended to use chlorine-containing water in coal preparation plants, because chloride ions will have a negative impact on coal quality and the environment. Here are some reasons:

1. Corrosiveness: Chloride ion is very corrosive, which will cause corrosion to coal processing equipment and pipelines, leading to the risk of equipment damage and leakage.

2. Damage to coal quality: Chloride ions will react with organic substances in coal to generate harmful substances such as chloride and hydrogen chloride, which will reduce the quality and calorific value of coal.

3. Environmental pollution: The use of chlorine-containing water in coal washing process will lead to the increase of chloride concentration in wastewater, which may pollute the water ecosystem if it exceeds the environmental protection standard.

Therefore, coal washing plants generally choose to use clean water to avoid the problems caused by chloride ions.