Samuel A Lolon

Interests

Research

Strategic planning for underground mine, safety-based mine design, mine ventilation, automation and drone application for mine operation

Teaching

Underground mine planning and operation, experiential-based learning, safety-based mine design, mine ventilation, mining project management

Courses

Scholarly Contributions

Journals/Publications

• Lolon, S. A., Brune, J. F., & Bogin, G. E. (2020).

  Study of Methane Outgassing and Mitigation in Longwall Coal Mines

  . Mining, Metallurgy & Exploration, 37, 1437-1449. doi:https://doi.org/10.1007/s42461-020-00287-6
• Lolon, S. A., Brune, J. F., Bogin, G. E., & Juganda, A. (2020). Study of Methane Outgassing and Mitigation in Longwall Coal Mines. Mining, Metallurgy and Exploration, 37(Issue 5). doi:10.1007/s42461-020-00287-6
  More info

  Historically, there have been many occurrences of mine fires and explosions recorded in the United States and other countries that have demonstrated the existence of explosive methane–air mixtures, herein referred to as explosive gas zones (EGZs). The risk of mine explosions can increase if the EGZs migrate out from the gob into the surrounding mine entries. Fluctuating barometric pressure is the common cause for EGZs outflowing or outgassing from the gob. Numerical analysis using a 3D computational fluid dynamics method was developed to fully understand the outgassing phenomenon. A number of simulations using various magnitudes and periods of barometric pressure changes indicated that the EGZ outgassing potentially occurs due to lags in pressure, which are strongly influenced by mine conditions and ventilation systems. An early warning system with a real-time pressure monitoring and the application of gob ventilation boreholes are recommended to detect and mitigate explosion hazards from gob outgassing.
• Lolon, S. A., Brune, J., Bogin, G., & Juganda, A. (2020).

  Study of Methane Outgassing and Mitigation in Longwall Coal Mines

  . Mining, Metallurgy & Exploration, 37, 1437-1449. doi:https://doi.org/10.1007/s42461-020-00287-6
• Lolon, S. A., Brune, J. F., Bogin, G. E., Grubb, J. W., Saki, S. A., & Juganda, A. (2017). Computational fluid dynamics simulation on the longwall gob breathing. International Journal of Mining Science and Technology, 27(Issue 2). doi:10.1016/j.ijmst.2017.01.025
  More info

  In longwall mines, atmospheric pressure fluctuations can disturb the pressure balance between the gob and the ventilated working area, resulting in a phenomenon known as “gob breathing”. Gob breathing triggers gas flows across the gob and the working areas and may result in a condition where an oxygen deficient mixture or a methane accumulation in the gob flows into the face area. Computational Fluid Dynamics (CFDs) modeling was carried out to analyze this phenomenon and its impact on the development of an explosive mixture in a bleeder-ventilated panel scheme. Simulation results indicate that the outgassing and ingassing across the gob and the formation of Explosive Gas Zones (EGZs) are directly affected by atmospheric pressure changes. In the location where methane zones interface with mine air, EGZ fringes may form along the face and in the bleeder entries. These findings help assess the methane ignition and explosion risks associated with fluctuating atmospheric pressures.
• Lolon, S. A., Brune, J., Bogin, G., Grubb, J., Saki, S., & Juganda, A. (2016).

  Computational Fluid Dynamics Simulation on the Longwall Gob Breathing

  . International Journal Mining Science and Technology, 27(2), 194-198. doi:https://dx.doi.org/10.1016/j.ijmst.2017.01.025
• Lolon, S., & Calizaya, F. (2009). Computational fluid dynamics study on hot spot location in longwall gob. Mining Engineering, 61(Issue 8).
  More info

  Spontaneous combustion is one of the main sources of fires in underground coal mines. Most of these fires are initiated in the caved area (gob). This process starts with the formation of hot spots, which may develop into the self-heating of coal. A study in volving experimental measurements and computational fluid dynamics (CFD) simulations was carried out to identify the location of these spots. Four CFD gob models of three different permeability zones were formulated and solved. Three utilized a bleeder ventilation system and the fourth a bleederless system. The simulation results showed that in a model ventilated by a bleeder system, the hot spot was located in the consolidated zone near the return side of the gob. Once the process was initiated, it propagated along the tailgate side as the gob progressed. The leakage flow through the gob played an important role in determining the size and location of the hot spot. In the model ventilated by a bleederless system, the hot spot was located by the face line. This was mainly caused by air leakage from the headgate. The study concludes with a set of ventilation schemes and recommendation to reduce the development of hot spots.

Proceedings Publications

• Lolon, S. A., Campbell, R., Edgar, I., & Haque, I. (2024, September).

  Implementation of Major Mining Strategy Changes at the Deep 
  Mill Level Zone (DMLZ) Mine, PT. Freeport Indonesia

  . In Proceedings of the 9th International Mass Mining Conference, 73-82.
• Lolon, S. A., & Brune, J. F. (2018). Barometric-induced gob breathing: Root cause, effect and recommended best practices. In 2018 SME Annual Conference and Expo and 91st Annual Meeting of the SME-MN Section - Vision, Innovation and Identity: Step Change for a Sustainable Future, 2018-.
• Juganda, A., Brune, J., Bogin, G., Grubb, J., & Lolon, S. (2017). CFD modelling of longwall tailgate ventilation conditions. In SME Annual Conference and Expo 2017: Creating Value in a Cyclical Environment.
  More info

  Face ignitions at the longwall face are a serious hazard in underground coal operation that can lead to a major mine explosion. Despite having methane monitoring system mounted on the shearer and at various locations on the longwall face, undetected accumulations of methane can still occur and result in face ignitions. With the use of Computational Fluid Dynamics (CFD), the interaction between the air flow at the longwall face and factors that contribute to the accumulation of methane around the longwall face can be modeled and visualized in great detail. The results confirm that the tailgate corner of longwall face is a critical area that is prone to face ignitions and needs to be properly monitored. The occurrence of roof falls on the tailgate entry inby the face and/or poor caving conditions behind the shields can pose a safety risk in the longwall operation. Poor gob caving can lead to insufficient face air quantity to dilute methane at the tailgate corner, while blocking of tailgate by a roof fall can carry methane contaminated air from behind the shields back into the face near the tailgate corner and pull the explosive gas zones (EGZs) inside the gob closer to the face.
• Lolon, S. A., Brune, J. F., Bogin, G. E., Grubb, J. W., & Juganda, A. (2017). Evaluation of gob pressure response due to changes in mine atmospheric pressure. In SME Annual Conference and Expo 2017: Creating Value in a Cyclical Environment.
  More info

  A longwall gob is mainly filled with broken rocks from the collapsed roof and becomes a porous medium where explosive methane-air mixtures can accumulate. In bleeder ventilation systems, this mixture can migrate out of the gob into the longwall face and other active areas in the mine during barometric or ventilation-induced pressure changes. When external pressures change, the gob does not perceive this disturbance instantly but with a delay due to air flow resistance in the porous gob material. The delay of gob response to outside pressure changes increases the pressure differential across the gob and may cause an outflow of explosive air mixtures from the gob into the adjacent bleeder entries. With computational fluid dynamics (CFD) modeling, researchers at the Colorado School of Mines have evaluated the impact of gob pressure fluctuations on the outgassing of the explosive gas zones (EGZs), the magnitudes and rates of pressure changes, the volumes as well as the potentials location of outgassing if it occurs.
• Lolon, S. A., Brune, J., Bogin, G., Grubb, J., & Juganda, A. (2017, March).

  Understanding Gob Outgassing Associated with Pressure Disturbances in Longwall Mine

  . In 16th North American Mine Ventilation Symposium, 14-17.
• Gilmore, R. C., Brune, J. F., Lolon, S. A., Juganda, A., Saki, S., Bogin, G. E., Zipf, R. K., & Grubb, J. W. (2016). Explosive gas zone formation in underground coal longwall bleeder ventilated gobs with an adjacent panel using CFD modeling. In 2016 SME Annual Conference and Expo: The Future for Mining in a Data-Driven World.
  More info

  Methane-air mixtures form explosive gas zones (EGZs) in underground longwall coal mine gob ventilation systems. Such EGZs have caused a number of fatal mine explosions, including the 2010 disaster at the Upper Big Branch mine, where 29 miners lost their lives. Researchers at the Colorado School of Mines use Computational Fluid Dynamics (CFD) modeling to predict EGZ locations. In this paper, a model of a bleeder-ventilated gob system includes two adjacent panels, an active longwall and a mined-out gob. Boundary conditions for the simulations match statutory ventilation conditions for methane concentrations and air flow rates at common measurement points throughout the mine. The modeling results predict the persistence of EGZs in the gob that may compromise the effectiveness of the bleeder ventilation system.
• Lolon, S., Brune, J., Gilmore, R., Bogin, G., Grubb, J., Saki, S., & Juganda, A. (2016). CFD studies on the phenomenon of gob breathing induced by barometric pressure fluctuations. In 2016 SME Annual Conference and Expo: The Future for Mining in a Data-Driven World.
  More info

  In longwall mines, atmospheric or barometric pressure fluctuations can disturb the pressure balance between the gob and the ventilated working area of the mine, resulting in a phenomenon known as "gob breathing". Gob breathing triggers a gas flow across the gob and the working areas and may result in a condition where a methane accumulation in the gob flows into the face area forming an explosive mixtures. This paper discusses results of Computational Fluid Dynamics (CFD) modeling carried out to analyze this phenomenon and its impact on the explosive mixture development under a bleederventilated longwall gob panel scheme. Modeling results indicate that the gas inflow and outflow across the gob and the formation of Explosive Gas Zones (EGZs) are directly affected by the barometric pressure changes. Methane gas and EGZs in the gob expand out toward the face and bleeder entries during the falling barometric pressure. Where methane zones interface with mine air, EGZ fringes may form along the face and in the bleeder entries. When the atmospheric pressure increases, an ingression of oxygen into the gob is observed that can also increase EGZs in volume. The findings from this study help assess the methane Ignition and explosion risks associated with fluctuating atmospheric pressures.
• Saki, S. A., Brune, J. F., Bogin, G. E., Grubb, J. W., Gilmore, R. C., & Lolon, S. A. (2016). Optimization of Gob ventilation boreholes completion parameters. In 2016 SME Annual Conference and Expo: The Future for Mining in a Data-Driven World.
  More info

  Gob ventilation boreholes (GVBs) are widely used in underground coal mines for longwall gob degasification purposes. GVBs are often drilled within 10 to 30 m above the top of the coal bed into the fractured zone, completed with 20 cm (8 in.) diameter casing and 60 m of slotted pipe at the bottom. The purpose of this completion strategy is to create a pressure sink to capture the emissions before they can enter into the underground workplace. For GVBs to work effectively, they must be drilled close enough to the working areas to capture methane from the fractured zone while the setting depth must be kept above the caved zone to minimize the amount of ventilation air that is drawn into the GVBs. Well completion parameters are important for creating safe working conditions. In this paper, computational fluid dynamics (CFD) studies will be presented to analyze the effect of different practices for GVBs completion parameters for methane extraction, formation of explosive gas zones in the gob and methane concentrations at the longwall face and tailgate. Authors have identified the optimum completion parameters for GVBs, which can maximize the benefit and minimize fire and explosion risk.
• Grubb, J., Brune, J., Zipf, R., Bogin, G., Marts, J., Gilmore, R., & Lolon, S. A. (2015, March).

  Managing the Risk of Spontaneous Combustion in Underground Coal Mines

  . In 15th North American Mine Ventilation Symposium, 547-554.
• Lolon, S., & Calizaya, F. (2009). CFD study on hot spot location in longwall gob. In SME Annual Meeting and Exhibit and CMA's 111th National Western Mining Conference 2009, 1.