NIWM equipment design and operation NIWM equipment design The water mist spray technology is diverse and increasingly mature, and its application range is gradually expanding.
Fig 1. Design of NIWM goaf fire prevention and extinguishing equipment. Fig 2.
Changes in pore structure of coal caused by coal-to-gas bioconversion
Internal structure and atomisation effect of the gas—liquid two—phase flow atomising nozzle. Theoretical derivation of operating parameters of NIWM equipment. Substituting the relevant parameters into Eq 3 , 4 For a constant flow, according to the conservation of mass, 5 Eqs 1 — 5 constitute the equations for solving the gas and liquid mass flow rate of the gas-atomising nozzle. Experimental verification of NIWM equipment operating parameters.
Fig 3. Experimental system for operating parameters of NIWM fire prevention and extinguishing equipment. Fig 4. Effect of gas pressure change on gas and liquid mass flow water pressure is 2 MPa, gas pressure is 0. Fig 5. Effect of water pressure change on gas and liquid mass flow water pressure is 0. Fig 6. Effect of gas—liquid mass flow ratio on water mist particle size water pressure is 2 MPa, gas pressure is 0. Fig 7. Effect of gas-liquid mass flow ratio on water mist particle size water pressure is 0. Experimental research on NIWM fire prevention and extinguishing Experimental equipment and scheme In general, the oxidative exothermic of coal in low temperature stage is the direct cause of spontaneous combustion of coal[ 24 — 26 ].
Fig 8. Experimental setup of NIWM fire prevention and extinguishing. Inhibiting low temperature oxidation of coal by NIWM. Extinguishing high temperature combustion of coal by NIWM. Results and discussions Inhibiting low temperature oxidation of coal by NIWM In terms of self-heating of coal, the low temperature region is an important stage of coal spontaneous combustion and has always been the focus of research[ 28 , 29 , 34 — 40 ].
Fig 9. Fig Extinguish effect of NIWM on temperature of coal combustion. Design of field process flow The experiment results showed that NIWM has better effect on inhibiting spontaneous combustion and extinguishing combustion of coal. Onsite arrangement diagram of the NIWM fire prevention and extinguishing equipment in the goaf of a longwall working face.
Conclusions In this paper, the NIWM fire prevention and extinguishing technology was proposed, and the corresponding equipment was designed and manufactured. Acknowledgments The authors are very grateful to the editors and reviewers for their kind and invaluable comments. References 1. Coal mine fires and human health: What do we know?
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View Article Google Scholar Assessment of the contribution of in-situ combustion of coal to greenhouse gas emission; based on a comparison of Chinese mining information to previous remote sensing estimates. Experimental research on inhibition performances of the sand-suspended colloid for coal spontaneous combustion.
Safety Science. Fine coal covering for preventing spontaneous combustion of coal pile. Changes on the low-temperature oxidation characteristics of coal after CO 2 adsorption: a case study. Journal of Loss Prevention in the Process Industries. Aqueous three-phase foam supported by fly ash for coal spontaneous combustion prevention and control. Advanced Powder Technology. Flow characteristic investigation of inhibition foam used for fire extinguishment in the underground goaf.
Liu H. Experiment research for the prevention and control of mine goaf fire using gas-liquid two phase flow, Taiyuan, Chen Y, Wu W. Thermal Engineering-3rd Edition, Beijing, Yan C. Nukiyama S. Experiments on the atomization of liquids in an air stream, report 3, on the droplet-size distribution in a atomized jet. Trans Soc Mech Eng Japan. Spray development and droplet characteristics of high temperature single-hole gasoline spray. Malvern Instruments: new Insitec LPS provides complete solution for continuous wet particle size measurement.
Journal of Cell Science. Ceas Space Journal. The mechanism at the initial stage of the room-temperature oxidation of coal. Combustion and Flame. Taraba B, Michalec Z. Effect of longwall face advance rate on spontaneous heating process in the gob area—CFD modelling. Kuenzer C, Stracher GB. Geomorphology of coal seam fires. The fire extinguishing performances of foamed gel in coal mine. Journal of hazardous materials. An intelligent gel designed to control the spontaneous combustion of coal: fire prevention and extinguishing properties.
Smoldering combustion of coal under forced air flow: experimental investigation. Journal of Fire Sciences. Large-area goaf fires: a numerical method for locating high-temperature zones and assessing the effect of liquid nitrogen fire control.
Environmental Earth Sciences. The relationship between oxygen consumption rate and temperature during coal spontaneous combustion. Safety science. Wang H, Chen C. Experimental study on greenhouse gas emissions caused by spontaneous coal combustion. Ultrasonic extraction and oxidation characteristics of functional groups during coal spontaneous combustion. Journal of Thermal Analysis and Calorimetry. Coal oxidation at low temperatures: oxygen consumption, oxidation products, reaction mechanism and kinetic modelling.
Progress in energy and combustion science. Arisoy A, Beamish B. Reaction kinetics of coal oxidation at low temperatures. Novel authigenic gas foaming hydrogels for preventing coal spontaneous combustion. Self-heating of coal and related materials: Models, application and test methods. Preventing spontaneous combustion of coal from damaging ecological environment based on thermogravimetric analysis.
Mining Science and Technology China. A review on water in low rank coals: the existence, interaction with coal structure and effects on coal utilization. Fuel Processing Technology. Performance of water-based foams affected by chemical inhibitors to retard spontaneous combustion of coal. International journal of mining science and technology. An experimental approach to selecting chemical inhibitors to retard the spontaneous combustion of coal. More Well before , Britain had become heavily dependent upon coal for its fuel, and coalmining had taken its place among the nation's staple industries.
Authors Affiliations are at time of print publication. Print Save Cite Email Share. Show Summary Details. Subscriber Login Email Address. Library Card. View: no detail some detail full detail. Part I Towards the Age of Coal.
Chapter 1 Towards the Age of Coal. Chapter 4 Regional Developments and National Trends. Chapter 5 The Coalfields of Britain. Chapter 6 Mines and the Techniques of Mining.
Chapter 7 Ownership and Enterprise. Chapter 8 Management. Chapter 9 Labour Relations and Work Discipline. Improved coal processing also offers the potential to minimize existing environmental problems and potential future issues. Many of these piles are environmental liabilities being dealt with under the federal Abandoned Mine Land reclamation program, but a growing number are being viewed as potential opportunities for utilization.
Pennsylvania has 14 sites at which circulating. Improved coal processing also offers potential for responding to future environmental requirements. For example, the development of new or modified flotation processes permit fuel oil to be replaced as a froth flotation collector if it is prohibited because of disposal concerns. There are two technical areas where the development of improved coal processing technologies offers the greatest potential to increase resource recovery Peterson et al.
The use of improved information technology, perhaps in conjunction with improved online analysis capabilities, to optimize the performance and efficiency of existing unit operations; and. The development and deployment of better materials with which to construct vessels, separation devices, and conduits. The primary needs for research in the broad environmental area are to support the regulation of existing and future mining operations and to mitigate the effects of past mining practices.
Existing Mine Operations. There is still an incomplete understanding of how strata behave after coal is extracted from both surface and underground mines, and the hydrologic consequences of mining are not fully understood. For surface mining, the properties of the altered subsurface—particularly the leaching and permeability characteristics—are likely to be different compared to those existing prior to mining.
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For underground mining, the collapse of strata above a coal seam into the mined void can propagate all the way to the surface, damaging buildings and disrupting the quantity and quality of surface and subsurface water flows. Disposal of mine waste can be a significant problem, particularly where the coal has to be cleaned before shipment e. There is a need for enhanced understanding of the physical and chemical behavior of spoil stored in valleys or waste—from coal combustion or coal preparation plants—that is disposed in surface or underground mines. Waste management is a major problem where land either is not available or is more valuable for other productive uses.
Increased research to develop productive uses of mine waste offers considerable potential to reduce waste disposal issues. Mine Decommissioning and Closure. The major decommissioning and closure activities are 1 sealing of all access to underground mine areas, 2 removal of all surface facilities, and 3 reclamation of surface mine areas generally carried out concurrently with mining operations and the surface areas of underground mines. Underground and surface coal mines present different challenges for decommissioning and closure.
The critical factors in underground mining are the effects of subsidence and hydrology, both of which require continued monitoring and control. For surface mines, the critical factors relate to drainage and treatment of water and to erosion and sedimentation of the slopes, the waste and spoil banks, and the final pit.
Continued use of the surface mine infrastructure e. A mining plan that is well integrated with a community master plan can result in optimum post-mining use of this infrastructure. Abandoned Mined Lands.
A range of environmental issues e. This problem is particularly acute in the older coal mining districts of the eastern United States, specifically in the Appalachian hill country. Although mine closure today is a rigorously regulated process requiring detailed technical and financial analysis during the planning and operation stages for a mine—and ensuring financial and legal responsibility for post-mining closure—the nation continues to grapple with the effects of past mining practices.
Additional research is required to develop and demonstrate more effective and sustainable solutions to the problems of acid mine drainage, mine fires, and the utilization of waste piles from AML sites. In general, the scope of and motivation for research are determined by the relevance and potential impact of the problems that need to be dealt with by these various stakeholders. Industry participants in mining research include individual companies and mining company associations.
While the federal government continues to have extensive involvement in the regulation of the coal mining industry, its support for mining research has decreased substantially over the past 10 years. At present, federal research is focused primarily on health and safety. Some research is being done on environmental issues, but support for research aimed at advanced mining technologies. Engineering and Technology Development. Although not exclusively focused on extraction or on coal mining, many of the program outputs were applicable to the extraction phase of the coal fuel cycle.
Relatively little is being done by the federal government to address coal preparation issues. DOE-FE had a solid fuels program, although it tended to fund more advanced work—such as chemical coal cleaning—than processes related to conventional coal preparation. However, there has been no administration request for funding for this area in recent years, and the program is essentially defunct. Some research programs addressing a variety of mineral separation issues i. There is a low level of support for fundamental research in the earth sciences and engineering disciplines geosciences, material sciences, rock mechanics, etc.
Health and Safety. The NIOSH Mining Program has seven areas of health and safety research activity, addressing respiratory diseases, hearing loss, cumulative musculoskeletal injuries, traumatic injuries, disaster prevention, rock safety engineering, and surveillance and training. Reclamation and Rehabilitation of Abandoned Mined Lands. Among the stated purposes of SMCRA were to support research, training programs, and the establishment of research and training centers in the states on various aspects of mineral production.
Although the involvement of OSM with aspects of extraction research is minimal, OSM does have limited technical and applied science activities in support of its regulatory mission. In particular, OSM, in cooperation with the states, plays a major role with regard to the reclamation and rehabilitation of abandoned mined lands.
The environmental problems associated with active and abandoned mines and their abatement, particularly land reclamation and water quality maintenance, and the proper handling and disposal of the spoils and wastes from mining operations e. Environmental Protection Agency.
EPA is also involved in a program to promote the capture and utilization of coal bed methane. Overall, coal mining research in EPA is limited to support for its regulatory role. Mining Regulation. The Mine Safety and Health Administration, in the Department of Labor, provides technical support and training services to its personnel and to personnel from the mining industry through its Pittsburgh Safety and Health Technology Center and the National Mine Health and Safety Academy.
The direct involvement of MSHA in funding mining research is limited because of its primary regulatory role. However, MSHA undertakes field investigations, laboratory studies, and cooperative research activities on health and safety issues in support of its inspection and technical support functions. It also supports state miner training activities through its state grants program.
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State government involvement in coal mining and processing research is primarily dependent on the importance of the mining industry to each particular state. The major coal-producing states—Wyoming, West Virginia, Kentucky, Pennsylvania, Texas, Virginia, and Illinois—have or have had agencies with specific responsibilities for health, safety, and environmental issues associated with coal mining.
Further, mining industry organizations in these states work closely with state agencies to support research programs that address the specific needs of coal reserve estimation and coal mining operations. Some state governments have provided grants for coal processing research in academic departments e.
The mining industry is truly international—not only are mining operations carried out globally, but there is considerable capital, knowledge, and mined-materials flow across international boundaries to satisfy the global demand for mined and processed materials. The coal industries in different countries have much in common, particularly with regard to health, safety, and environmental issues. Because of these similarities, there is considerable exchange of research results—developments in one country are quickly incorporated into mining practices in other countries.
This global interaction is particularly facilitated by mining equipment manufacturers. The consolidation of coal mining equipment manufacturers over the past three decades and the broad applicability of equipment across a range of mining situations have led manufacturers to work with mining clients and their own suppliers to develop evolutionary improvements to their products.
In addition, equipment manufacturers invest substantial resources to improve the durability and reliability of mining equipment. Some equipment manufacturers have worked in partnership with government agencies and mining companies to develop and demonstrate new concepts e. For some equipment manufacturers, mining equipment is only one of many product lines. The applied engineering research and development work that they conduct is generally fundamental to their production and materials processes, and the research is often proprietary and not generally available to the wider industry.
Cross-industry research under the aegis of coal companies or coal industry organizations, or with support from industry organizations, appears to be minimal. There are no longer organizations such as Bituminous Coal Research, Inc. BCR that used to work on coal mining and coal preparation issues. Several coal companies work in partnership with government agencies and academic institutions on coal mining research projects. The importance to researchers of access to operating mines and input from mining company experts is particularly worth noting.
The funds are paid to Australian Coal Research Ltd. ACR , a company established by the industry to manage all aspects of the program. The research projects, which are conducted by university, industrial, and government-affiliated researchers, are monitored by industry representatives. Under this agreement, the government agrees to provide a certain level of funding each year to the CRC, and CRC participants agree to undertake certain activities and contribute specified personnel and resources.
This recognized the importance of developing research priorities for new technologies and joint sponsorships of chosen projects, and resulted in an NMA-DOE partnership that supported several roadmaps as part of the Mining IOF program. The more difficult mining conditions that will be encountered in the future will require improved methods to protect the health and safety of mine work-. A range of factors increase health and safety risks to the coal mining workforce, including the introduction of new equipment and systems; the commencement of mining in virgin areas; the infusion of new workers; and the mining of multiple seams, seams that are thinner, thicker, or deeper than those customarily mined at present and new seams that underlie or overlie previously mined-out seams.
All of these factors are likely to apply to some degree in future mines, irrespective of whether the higher production scenarios suggested in some forecasts eventuate. If they do materialize, then these risks are likely to become even more pronounced. There are major knowledge gaps and technology needs in the areas of survival, escape, communications systems both surface-to-underground and underground-to-underground , and emergency preparedness and rescue.
Additional risk factors that are likely to apply in the deeper mines of the future are the potential hazards related to methane control, dust control, ignition sources, fires, and explosions. Greater understanding and better prediction of strata behavior to prevent unanticipated 12 roof collapse, particularly problems associated with roof and side fall during thick seam extraction, are essential for maintaining and improving worker safety.
Federal support for health and safety research significantly decreased about a decade ago, and has essentially remained constant since that time. Recommendation: Health and safety research and development should be expanded to anticipate increased hazards in future coal mines. This should be coupled with improved training of the mining workforce in all aspects of mine safety. Roof collapse is anticipated during longwall mining after the coal has been removed see Appendix E.
Coal and Peat Fires: A Global Perspective
Most mining health and safety research by the federal government is carried out by the Mining Program at the National Institute for Occupational Safety and Health. Technology-related activities in the Mine Safety and Health Administration are limited to technical support and training services for its personnel and those from the mining industry. Coal mining has environmental impacts on air, water, and land. Actions taken to meet federal and state environmental regulations already respond to and ameliorate many of these effects. However, there are gaps in the knowledge base related to a range of environmental issues that need to be addressed, and future changes in environmental requirements may drive the need for new coal mining and beneficiation technology.
As mining extracts coal from deeper and operationally more difficult seams by both surface and underground methods, it is likely that many existing environmental issues and concerns will be exacerbated. New concerns, particularly related to greater disturbance of hydrologic systems, ground subsidence, and waste management at mines and preparation plants, are likely to arise.
Inadequate understanding of post-mining strata behavior and the associated hydrologic consequences of mining in both surface and underground mines affects mine permitting, mine development, environmental mitigation, and post-mining land use, including use for waste management. Research offers considerable potential to mitigate the effects of past mining practices, particularly acid mine drainage on abandoned mine lands. The regulatory environment framed by such statutes as the Clean Air and Clean Water Acts and technical support programs administered by both state and federal agencies, and implemented by mining companies through their compliance practices, are inadequately supported by existing research programs.
Recommendation: Additional research is needed to mitigate the adverse environmental impacts associated with past, existing, and future coal mining and processing. Research activities should focus particularly on developing techniques to mitigate the alteration and collapse of strata overlying mined areas, to model the hydrological impacts of coal mining, to improve mine mapping and void detection, to improve the stability of.
The committee recommends that OSM should be the lead agency in this effort, and it should coordinate closely with related EPA and state research activities. The productivity of U.