As an inert gas with non-combustible and non-oxidation-supporting characteristics, nitrogen has multiple application values in coal mine safety production. Shenger Gas (Hong Kong) Co., Ltd. is deeply involved in the field of industrial gases, providing high-purity nitrogen and nitrogen production system solutions to meet the demand for inert gases in the coal mining industry. This paper explores the main uses of nitrogen in coal mines and related technical solutions from the perspective of mine safety and production, and introduces the professional capabilities of Shenger Gas (Hong Kong) to help improve mine safety levels and production efficiency.
Nitrogen’s main role in coal mining
Mine fire prevention and fire suppression: The goafs formed after coal seam extraction often spontaneously combust due to the oxidation of legacy coal and can cause fires. Nitrogen injection technology isolates residual coal from oxygen by injecting high-purity inert nitrogen into the goaf, thereby slowing the spontaneous combustion process, inhibiting combustion and suffocating fire sources
. A large number of studies and engineering practice have shown that nitrogen injection to prevent fire is one of the more mature and effective methods. Once a fire hazard is discovered, nitrogen production equipment or liquid nitrogen vehicle can be activated to reduce the oxygen concentration in the fire area to below the combustion critical.
Gas Governance and Explosion Suppression: Mine gas (methane) is a flammable and explosive gas that poses an extreme threat to miner safety. Nitrogen can be used to depress the lower explosion limit of the gas mixture by reducing the oxygen concentration in a pipe or working face. As the US mine safety department points out, replacing the combustible environment with an inert atmosphere (mainly nitrogen) is an important means of preventing explosions
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By continuously injecting nitrogen and keeping the oxygen content in the field area below the explosive critical value (usually <12%), it can effectively suppress gas explosions and slow down spontaneous combustion of coal seams, helping to build a safe mining environment
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Inert filling and vaccination stabilization: In some high-risk mines, inert gas filling of the vaccination is an important precautionary measure. When the emptying zone is closed or sealed, liquid nitrogen or high-purity nitrogen can be passed in to form an inert protective layer that prevents oxygen penetration or coal oxidation
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. Industry codes require that the adoption of inert gas fire protection must be equipped with a dedicated conveyor piping system and meet low temperature and pressure resistant conditions
. By filling with nitrogen injection, it can not only effectively reduce the oxygen concentration in the goaf to prevent spontaneous combustion, but also reduce the impact of downhole ventilation disturbance on the confined area and maintain the stability of the field area.
Equipment protection and maintenance: In addition to safety protection against extraction systems, nitrogen can be used to protect all types of mine equipment. For example, nitrogen-filled inerting in equipment such as air separation devices, compressors, and transformers for coal mines can prevent oxidative corrosion of mechanical and electronic components and extend the life of the equipment. Nitrogen can be used as a cleaning inert medium to exclude hazardous gases during cleaning and pressure testing of pipelines and storage tanks. By implementing nitrogen protection for power systems and instrumentation equipment, it also avoids the risk of oxidative short circuits, meeting the requirements of safe production in modern mines.
Related technical solutions
Coal Mine Nitrogen Injection Systems: Nitrogen injection fire prevention requires specialized gas supply and delivery systems. Mine sites are generally configured with downhole nitrogen injection pipelines and injection pipe mouths to ensure continuous nitrogen injection
by circulating buried pipes and alternating segments. According to the requirements of the Coal Mine Safety Regulations, the use of nitrogen fire prevention and extinguishing must be equipped with a dedicated piping system and ensure nitrogen purity ≥ 97%
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. The common practice is to lay out Φ108mm steel pipes in the air inlet slot at the operating surface, using two-way nitrogen injection ports to inject alternately nitrogen to cover the entire oxidation zone.
In the specific design, it is necessary to be equipped with flow and pressure monitoring equipment, and dynamically adjust the nitrogen injection intensity according to monitoring data such as gas concentration and CO concentration, so as to achieve the goal of effective inerting.
Nitrogen Generator: The nitrogen generator is the key equipment for supplying high-purity nitrogen gas. Common industrial nitrogen generation technologies include PSA (Pressure Swing Adsorption) and membrane separation. The PSA nitrogen generator uses carbon molecular sieve as an adsorbent, featuring a simple structure, convenient operation, and high nitrogen purity, and is widely used in on-site nitrogen injection for coal mines
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. For example, a single DT-1000/6 carbon molecular sieve nitrogen generator can produce up to 1000 m³/h of nitrogen with a purity of ≥97%, meeting the continuous nitrogen injection demand of small and medium-sized mines. In explosive environments, explosion-proof electrical components must be adopted to ensure operational safety. The membrane separation nitrogen generation unit features a compact structure and high mobility, suitable for aboveground or underground emergency nitrogen injection. Whether PSA or membrane separation, the selection and installation of nitrogen generation equipment must comply with safety regulations and technical standards to ensure the purity and stability of the output gas mem.gov.cn.
Air Separation Equipment: Large mining areas can adopt cryogenic air separation units to produce liquid nitrogen or high-purity nitrogen, achieving continuous and stable gas supply. The cryogenic air separation plant utilizes low-temperature condensation principles to produce liquid nitrogen and oxygen, with an annual production capacity sufficient to meet the demand of million-ton-level coal mines. Compared with PSA systems, cryogenic air separation offers higher gas output and purity but requires greater investment and maintenance costs. Industry standards allow multiple configuration schemes, including fixed cryogenic air separation units, fixed or mobile PSA nitrogen generators, and aboveground/underground mobile membrane nitrogen systems
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, to meet the needs of different mine scales and application scenarios. Air separation systems are often equipped with backup storage tanks and supply pipelines to provide emergency nitrogen during main system maintenance or unexpected shutdowns, thereby enhancing on-site risk resistance.
On-site Integrated Solution: To ensure the safety and reliability of the nitrogen injection system, mines must also be equipped with corresponding monitoring and control devices. Modern nitrogen injection solutions usually include a complete gas monitoring system (for gases such as CO, O₂, and CH₄), pressure and flow control valves, as well as remote start control programs. Mobile liquid nitrogen pumping equipment can rapidly inject liquid nitrogen into underground areas during emergencies, while meeting the pipeline’s low-temperature and pressure-resistance requirements
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. For large-scale mines, the EPC turnkey model can provide a complete solution covering design, manufacturing, installation, and commissioning, effectively integrating nitrogen generators, air separation units, nitrogen injection pipelines, and monitoring systems to ensure overall system integrity and construction quality. Both domestic and international mining practices have proven that combining multiple fire prevention and control technologies (such as nitrogen injection, grouting, and inhibitor spraying) yields the best results
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Shenger Gas (HK) Solutions
Shenger Gas (Hong Kong) Limited, relying on the technical strength and industry experience of Zhejiang Shenger Gas, provides customized nitrogen solutions for coal mines. From equipment manufacturing to system integration, Shenger Gas possesses EPC turnkey capabilities in nitrogen generators, oxygen generators, dryers, and cryogenic air separation units, supported by a comprehensive R&D and service team
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The company designs efficient nitrogen generation systems and injection pipeline networks based on actual mine requirements, equipped with essential pipeline monitoring instruments and safety valves. As Shenger Gas (Hong Kong) continues to expand its presence in the Hong Kong and Greater Bay Area markets, it actively shares industry updates and technological achievements on LinkedIn (https://www.linkedin.com/feed/) and X (Twitter @shengergas), providing clients with the latest information.
With reliable product quality and professional service, Shenger Gas (Hong Kong) has earned the trust of thousands of enterprises domestically and abroad. The company is capable of undertaking various gas engineering projects, offering professional support for nitrogen injection and air separation gas supply in the coal mining industry.
Summarize
In summary, nitrogen is widely used in the coal mining industry as an essential inert gas medium for fire prevention and extinguishing, gas explosion suppression, inert filling, and equipment protection. Through modern nitrogen generators and air separation units, high-purity nitrogen can be produced on-site. When combined with advanced nitrogen injection technology and monitoring systems, it can significantly improve mine safety levels
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As a professional gas solution provider, Shenger Gas (Hong Kong) Limited leverages its extensive technical experience and integrated solutions to help mines achieve efficient nitrogen injection and management. In coal mine fire prevention and safety practices, it is essential to adhere to industry standards and research findings, continuously optimizing nitrogen injection and inert gas system designs to provide a solid foundation for safe mine operations.
