Optimization of Nitrogen Injection Parameters for a Partial W‑Type Ventilation Goaf at Duanwang Mine

Area of Science:

• Mining Engineering
• Chemical Engineering
• Safety Science

Background:

• Coal spontaneous combustion in goaf areas poses significant fire risks.
• Effective prevention strategies are crucial for mine safety and operational continuity.
• Nitrogen injection is a promising method for mitigating spontaneous combustion.

Purpose of the Study:

• To optimize nitrogen injection parameters for preventing coal spontaneous combustion in goaf.
• To establish a reliable oxygen criterion for the suffocation zone.
• To analyze the effects of gas drainage and nitrogen injection on oxidation zones.

Main Methods:

• Closed oxygen consumption tests were conducted.
• Field data were used to calibrate the oxygen criterion.
• A numerical model of a goaf panel with partial "W" ventilation was established.

Main Results:

• Increasing gas drainage narrowed the oxidation zone on the conveyor side but expanded it on the track side.
• Oxidation zone width decreased with injection distance up to 40m, then slightly increased.
• Optimal nitrogen injection rate was found to be 145.5 m³/h, decaying exponentially with higher rates.

Conclusions:

• The study provides practical guidance for fire prevention in goaf areas.
• An optimal nitrogen injection strategy can effectively control spontaneous combustion risks.
• Numerical modeling and experimental data are key to optimizing safety measures.