Longwall stone dust requirement is which of the following?

• A. 100 kg/operating hr
• B. 120 kg/operating hr
• C. 150 kg/operating hr
• D. 200 kg/operating hr

Answer: (C)

Stone dusting on the longwall is an inerting measure aimed at coating and diluting coal dust to reduce explosion risk. The rate at which stone dust is applied is set to match typical face conditions and ventilation, so enough dust is deposited to achieve effective inerting without waste.

The standard rate is 150 kg per operating hour. This amount provides adequate coverage along the longwall face and in the ventilation stream under common airflows. Rates like 100 or 120 kg/h are generally too low to maintain inert conditions across the whole face, while 200 kg/h is more than necessary for standard conditions and adds unnecessary handling. So 150 kg/operating hour is the appropriate, balanced requirement.