What is the minimum air quantity that must be delivered to the intake of a pillar line?

The minimum air quantity that must be delivered to the intake of a pillar line is 9,000 cubic feet per minute. This requirement is based on the need for adequate ventilation in underground mining operations, which is crucial for maintaining air quality and ensuring the safety of miners.

The specified air quantity helps to dilute and remove harmful gases, dust, and other contaminants that may be present in the mining environment, enabling a safe working atmosphere. Adequate ventilation is not only a regulatory requirement but also a practical necessity for preventing health issues and reducing the risk of incidents related to poor air quality.

The other potential answers, while they may include significant air flow rates, do not meet the established minimum requirement outlined by safety and health regulations specific to mining operations. The choice of 9,000 cubic feet per minute aligns with industry standards aimed at providing effective ventilation in pillar extraction areas.