Environmental Challenges and the Future of Mining
Pengfei Wang* and Jianan Liu
College of Mining Engineering, Taiyuan University of Technology, China
Submission: January 20, 2020; Published: February 26, 2020
*Corresponding author: Pengfei Wang, College of Mining Engineering, Taiyuan University of Technology, China
How to cite this article: Pengfei Wang, Jianan Liu. Environmental Challenges and the Future of Mining. Insights Min Sci technol.2020; 1(5): 555575. DOI:10.19080/IMST.2020.01.555575
Abstract
Great achievements have been made in mining industry to extract mineral and ore deposits. In this paper, significance of mining technology is introduced firstly. The course and history of mining technologies as well as the progresses made in the past have been summarized. Environmental issues associated with mining are discussed. The power determines the direction and propels the advance of mining technology is analyzed. It is concluded that the mining technology in the future is going to be safer, more intelligent, comprehensive, interdisciplinary and environmentally friendly. The mining objects will shift from traditional reserves to unconventional resources such as geothermal energy, methane clathrate, etc., from the earth’s crust to the earth deeper core, the deep ocean and the outer space. The intensified competition between countries on resources will expedite the advance of new mining technologies and legislation for the United Nations to protect environment of competition around the world.
Keywords: Mining technology; Environmental issues; Unconventional resources; Methane clathrate; Moon mining
Introduction
Minerals are very important in our lives. They are fundamental components of everyday items ranging from tires, concrete, cell phones, motor vehicles to toothpaste, lipstick and makeup, etc. (Figure 1). Gasoline, electricity, plastics, cosmetics, steel, glass, concrete, fertilizer, and food additives are all derivative of such raw earth materials as oil, coal, asphalt, iron, silica, limestone, phosphate, etc. [1]. Data published by The World Mineral Production show that mineral production in Europe still slightly increased from 2013 to 2017 despite the world economic downturn [2]. Mineral production as well as prospecting in other parts of the world increased significantly from 1970 to 2017 and are increasing now [3]. But we are not able to get mineral and ore deposits if it were not for the mining technologies (Figure 2).
Development of Mining Technology before 21st Century
In the pioneering days, mining was hard and hazardous manual work before invention of productive equipment and blasting agents. Mineral deposits were mined manually using pick and bars, transported by wheelbarrows in pioneering days. Mining technologies have developed considerably over past 200 years and spurred the boom of other industries. The steam engine was first used for draining coal mines. The first rail transportation, the first steam locomotive, and the first electric locomotive were all invented for coal mines. Hydraulic powered shield, armoured face conveyor, and shearer, etc. were invented in 1900s for coal mines [4]. Technical and innovative development of equipment is making mining safer and more efficient. The power is transformed from pneumatic to hydraulic, the haulage from rail bound to trackless, rock drills from handheld to rig mounted, and lately, operation from manual to computerized. Apart from the mining equipment, many advanced mining methods have been put forward. In addition to open pit mining, such high efficient underground mining methods as room and pillar method, sublevel caving, cut and fill, longwall top coal caving, solution mining (use drilled wells to dissolve the minerals with solutions), hydro-fracking, etc. are gaining great developments.
Concerns and Issues Related to Mining
Despite the development of mining technology, however, more attention has been paid to mine safety, low resource recovery, environment issues (Figure 3) including destruction of landscapes, water contamination and air pollution, etc. [5-8]. Mining activity has a profound influence on reshaping topography. Topsoil for open pit mining is removed on a large scale leading to the transformation of the landscape, deforestation, water contamination, etc. Dust at mining operations can be caused by drilling and blasting operations, trucks being driven on unsealed roads, ore crushing and wind blowing over areas disturbed by mining; Main sources of noise pollution are blasting, movement of heavy earth moving machines, drilling and handling plants [9-11].
Underground mining methods such as room and pillar method, longwall mining with coal pillars etc. give rise to wavy deformation on ground surface which is detrimental to buildings and structures [12]. Subsidence troughs over abandoned mines frequently occur when the overburden sags due to failure of remnant coal pillars or an inadequate backfill. Time-dependent failure of pillars may cause devastating disasters. 437 people were killed in Coalbrook disaster due to cascading pillar failure [13]. Room-and-pillar mining had ceased 118 years before sandstone beds collapsed abruptly over workings in Lanark, Scotland [13]. 9 percent of total potential subsidence occurred during a 6-year period after a 166-m-deep longwall face advance stopped at Peterlee, UK [14]. Many coal mines in South Africa also experienced and are experiencing severe pillar failure problems [15]. What’s more, mining and mineral-processing wastes are one of the world’s largest chronic waste concerns because several environmental problems are associated with the disposal of this waste, including contamination of streams and lakes and pronounced landscape transformation [16]. Ensuring safety and no destruction would occur or the damaged area is able to be repaired during or after mining activities is of great significance for sustainable development of mining industry as well as the society. Prevention is far better than cure. Therefore, mining technology should be safe, high recovery, and environmentally friendly or “green” oriented.
Recent Advance and Future Direction of Mining
Keep pace with the times, “green mining technologies” were proposed covering a wide spectrum including water-protectionmining, backfilling mining, gasification and liquefaction of underground ore body, partial extraction, bed separation grouting to reduce surface subsidence, underground discharge of rock refuse, simultaneous extraction of multiple resources, gradual and complete subsidence by leaving no pillars (extracting all pillars out), advanced deep mining, high recovery mining method, etc. [17-19]. In accordance with “green mining technologies”, “clean mineral” technologies are promising solution for China to meet its carbon reduction targets while still obtaining a considerable share of energy from coal. Significant progress is being made in these technologies to ensure the sound development of mining industry.
With the large amount consumption of resources of society, especially during the past several decades, easily mined deposits are being depleted. Deposits are less favorable due to rapidly increasing cover depth and larger inclination of ore bodies, reserves become more limited and precious. Due to limitation of technologies in the past, large amount of remnant natural resources are left unmined. Figure 4 shows an example of large portion of unmined remnant coal left underground. As pointed out earlier, devastating disasters may occur due to deterioration of those remnant pillars. Gob (void space or that filled by caved material after extraction of ore body) has high risk of spontaneous combustion and water inrush. Moreover, increase of cover depth gives rise to many problems in practice. Large ground pressure and severe roadway deformation are big challenges for safe mining as dynamic disasters such as rock bursts are related to depth. Some technologies have been proposed for deep mining and recovery of residual resources. Split-level longwall mining is an emerging mining method suitable for coal, trona, potash, etc. and is widely spread in China, Australia, etc. to cope with difficulties in deep mining [20]. Fluidized mining mentioned earlier is also a very promising mining method for deep resources [17].
To ensure safety, mining without a person in site or unmanned mining is a promising trend. The U.S. is well known for their small number of personnel working in mines. China now has several underground mines where no people can be seen at the working face. Thanks to the development of artificial intelligence and manufacture of machines, by constructing real-time network accompanied with remote sensing system covering whole mine, accurately controlling mining machines in the office is possible. With the depletion of conventional fossil energy resources such as oil, coal, natural gas, some unconventional, alternative and emerging energy resources such as shale gas, geothermal energy and nuclear energy are more popular. As mines go deeper, geothermal energy, a type of cutting-edge renewable energy, is gaining increasing attention. Scientists are endeavoring to use deep geothermal for generating electricity, heating and cooling buildings, etc. since it is clean and sustainable. Another concern of depletion of reserves is that the number of abandoned mines is larger. Some researchers developed methods to recover residual resources in abandoned mines [21]. Some on the other hand proposed to reuse them for tourism, refuse disposal, underground storage of water and energy, even building underground cities, etc. as well as develop ecological restoration plans for reclamation [22- 25]. In addition to resort to deep deposits underground, resources deep inside the Oceans are also a promising direction. Methane clathrate, for instance, is gaining significant attention. One cubic meter of methane clathrate releases about 160 cubic meters of gas making it a highly energy-intensive fuel. South China Sea claimed that methane clathrate had been produced continuously for 60 days, the output was over 300,000 cubic meters with 99.5% methane.
face. Thanks to the development of artificial intelligence and manufacture of machines, by constructing real-time network accompanied with remote sensing system covering whole mine, accurately controlling mining machines in the office is possible. With the depletion of conventional fossil energy resources such as oil, coal, natural gas, some unconventional, alternative and emerging energy resources such as shale gas, geothermal energy and nuclear energy are more popular. As mines go deeper, geothermal energy, a type of cutting-edge renewable energy, is gaining increasing attention. Scientists are endeavoring to use deep geothermal for generating electricity, heating and cooling buildings, etc. since it is clean and sustainable. Another concern of depletion of reserves is that the number of abandoned mines is larger. Some researchers developed methods to recover residual resources in abandoned mines [21]. Some on the other hand proposed to reuse them for tourism, refuse disposal, underground storage of water and energy, even building underground cities, etc. as well as develop ecological restoration plans for reclamation [22- 25]. In addition to resort to deep deposits underground, resources deep inside the Oceans are also a promising direction. Methane clathrate, for instance, is gaining significant attention. One cubic meter of methane clathrate releases about 160 cubic meters of gas making it a highly energy-intensive fuel. South China Sea claimed that methane clathrate had been produced continuously for 60 days, the output was over 300,000 cubic meters with 99.5% methane.
Conclusion
From the development of the mining history we can conclude that in the future, the mining technology is going to be safer, more intelligent, comprehensive, interdisciplinary and environmentally friendly. The mining objects will shift from traditional reserves to unconventional resources such as geothermal energy, methane clathrate, etc., from the Earth’s crust to deeper core, the ocean and even outer space (Figure 5).
To meet the requirement of environment and increasing demand of mineral resources for the time being and near future, many countries are developing policies as well as technologies. For instance, China is now implementing rehabilitation and restoration of mine geological environment, advocating green exploration, and comprehensively advancing the construction of green mines. China has clearly defined four support policies - mining right policy, land use policy, fiscal policy and financial policy, and established a series of typical models of green mine construction to protect our planet. In the future, the intensified competition between countries on resources in the deep underground, the ocean and even outer space will expedite the advance of new mining technologies and legislation for the United Nations to keep good environment of competition for this world.
Acknowledgement
The authors are thankful to the anonymous reviewers for their kind suggestions.
Funding
This study was funded by the National Natural Science Foundation of China, Young Scientists Fund (No. 51804209); NSFCShanxi Joint Fund for Coal-Based Low-Carbon Technology (No. U1710258), and Shanxi Applied Basic Research Programs, Science and Technology Foundation for Youths (No. 201801D221363).
References
- Loren EB (2009) Visualizing Earth History. Wiley in collaboration with the National Geographic Society.
- Brown TJ, Idoine NE, Raycraft ER, Shaw RA, Deady EA, et al. (2017) World mineral production. British geological survey. Keyworth, Nottingham.
- Ministry of Natural Resources of China (2018) China Mineral Resources. Geological publishing house, Beijing.
- Miller FP, Vandome AF, Mcbrewster J (2010) History of Coal Mining. Alphascript Publishing.
- Kenneth G, James B, Meredith F, Michael G, Charles K, et al. (2016) Reforming the U.S. coal leasing program. Science 354(6316): 1096-1098.
- El Bizri HR, Macedo JC, Paglia AP, Morcatty TQ (2016) Mining undermining Brazil's environment. Science 353(6296): 228.
- Wedding LM, Reiter SM, Smith CR, Gjerde KM, Kittinge JN, et al. (2015) Managing mining of the deep seabed. Science 349(6244): 144-145.
- David PE, William FL (2015) Preventing tropical mining disasters. Science 350(6267): 1482.
- Sosa M, Zwarteveen M (2014) The institutional regulation of the sustainability of water resources within mining contexts: accountability and plurality. Current Opinion in Environmental Sustainability 11: 19-25.
- Blanchette ML, Lund MA (2016) Pit lakes are a global legacy of mining: an integrated approach to achieving sustainable ecosystems and value for communities. Current Opinion in Environmental Sustainability 23: 28-34.
- Bogdan C, Gordon BS, Boyce MS (2016) Large Omnivore Movements in Response to Surface Mining and Mine Reclamation. Sci Rep 6(1).
- Wang P, Zhao J, Chugh YP, Wang Z (2017) A novel longwall mining layout approach for extraction of deep coal deposits. Minerals 7(4): 60.
- Malan DF, Napier JAL (2011) The design of stable pillars in the bushveld complex mines: A problem solved? The Journal of the Southern African Institute of Mining and Metallurgy 111: 821-836.
- Lee FT, Abel JF (1983) Subsidence from underground mining: Environmental analysis and planning considerations. In Publications of the Geological Survey, US Geological Survey: Reston, VA, USA.
- Merwe JNVD (2006) South African coal pillar database. Journal of the Southern African Institute of Mining & Metallurgy 106(2): 115-128.
- Bian Z, Miao X, Lei S, Chen SE, Wang W, et al. (2012) The challenges of reusing mining and mineral-processing wastes. Science 337(6095): 702-703.
- Heping X, Yang J, Shihua R, Feng G, Jianzhong L, et al. (2019) Theoretical and technological exploration of deep in situ fluidized coal mining. Frontiers in Energy, 13: 603–611.
- Qian M, Xu J, Miao X (2003) Green Technique in Coal Mining. Journal of China University of Mining & Technology 32(4): 344-348.
- Li L, Xu LJ, Chen DM (2013) Connotation and Technology System of Green Mining of Manganese Resources. Advanced Materials Research 734-737: 540-545.
- Guorui F, Pengfei W, Chugh YP (2019) Stability of the Gateroad Next to an Irregular Yield Pillar: A Case Study. Rock Mechanics and Rock Engineering 52(8): 2741-2760.
- Shengyong H, Zhang A, Guorui F, Shuwen G, Xiangqian G (2017) Impact of Coalbed Incidence Angle on Methane Enrichment Zone in Longwall Gob. Minerals 7(9): 166.
- Manca PP, Desogus P, Orru G (2014) The reuse of abandoned Acquaresi mine voids for storage of the Masua flotation tailings. International Journal of Coal Science & Technology 1(2): 213-220.
- Pudlo D, Ganzer L, Henkel S, et al. (2013) The H2STORE Project: Hydrogen Underground Storage – A Feasible Way in Storing Electrical Power in Geological Media? Clean Energy Systems in the Subsurface: Production, Storage and Conversion. Springer Berlin Heidelberg, pp. 395-412.
- Zhenqi H, Yanhua F, Wu X, Yanling Z, Tingting W (2015) Ecological restoration plan for abandoned underground coal mine site in Eastern China. International Journal of Mining, Reclamation and Environment 29(4): 316-330.
- Tan Z, Roberts AC, Christopoulos GI, et al. (2018) Working in underground spaces: Architectural parameters, perceptions and thermal comfort measurements. Tunnelling & Underground Space Technology 71: 428-439.
- Levine A (2016) Looking to space as an asteroid miner. Science.
- Jesse D (2017) Space Prospecting. Scientific American 317: 14-16.
- Andrew L (2005) Mining the Moon. Science.
- Billionaire teams up with NASA to mine the moon. Susan Caminiti, special to CNBC.com.
- Dworkin JP, Adelman LA, Ajluni T, Andronikov AV, Apont JC, et al. (2018) OSIRIS-REx Contamination Control Strategy and Implementation. Space Science Reviews 214(1).
- Yang G, Steve C (2017) Review on Space Robotics: Towards Top-Level Science through Space Exploration. Science Robotics 2(7).
- Dan L, Hodges K, Anderson RC (2017) Exploration telepresence: A strategy for optimizing scientific research at remote space destinations. Sci Robot 2(7).