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Status and prospects of underground thick coal seam mining methods
Published in Xia-Ting Feng, Rock Mechanics and Engineering, 2017
Hydraulic mining has several advantages over conventional mechanized mining methods. The advantages of hydraulic mining are: Mining layout is similar to that for conventional mechanized bord and pillar mining; however, the level of mechanical complexity is significantly reduced.Due to a reduction in the production of coal dust, the elimination of frictional ignition sources, the removal of personnel from the face area and the ability to automate equipment operation, hydraulic mining can be relatively safer than more traditional underground coal mining methods.Extraction of thin (0.3–1.5m), thick (> 4.5m) and steeply dipping seams has, in the past, challenged traditional mechanized techniques. However, hydraulic mining has had great success in such geologies.Typically the tonnages obtained from hydraulic mining operations are less than those obtained from mechanized methods. However, due to reduced manning requirements and lower capital costs, hydraulic mining is still highly productive.Hydraulic mining offers significantly lower capital and operating cost structures over conventional mines.Hydraulic mining is operationally flexible and can be used to extract areas of working mines where mechanized methods would otherwise encounter operational difficulties or would be economically unfeasible.Provided mine layout is designed appropriately, hydraulic mining can cope with large scale structural disturbances; and as a result the profitability of a hydraulic mining operation is less affected by these constraints.
Assessment of heavy metal pollution associated with tailing dam in gold mining area, southern ethiopia
Published in Geosystem Engineering, 2023
Gera Techane, Geremew Sahilu, Lena Alakangas, Worku Mulat, Helmut Kloos
The history of gold mining in southern Ethiopia dates back to the 1930s when placer gold was first discovered. Since then, placer gold has been mined in the area using panning and semi-mechanized hydraulic mining methods. Primary gold production by the open-pit mining method was commenced in the late 1980s. The gold deposit in the area is associated with pyrite (FeS2), chalcopyrite (CuFeS2), galena (PbS), sphalerite (ZnS), arsenopyrite (FeAsS), and other ores (Zenebe, 2006). Pyrite is one of the environmental problems in the mining industry because it releases heavy metal contaminants (Alvarenga et al., 2021; Ardejane et al., 2008). Especially the Legadembi gold deposit is rich in sulfide minerals including pyrite. These minerals, particularly sulfides in the ore aggregate are the major source of heavy metals in the study area (Getaneh & Alemayehu, 2006).
Environmental Alchemy: Mercury-Gold Amalgamation Mining and the Transformation of the Earth
Published in Ambix, 2023
In the global history of gold mining in the second half of the nineteenth century,53 the California gold rush offers an extreme example of the wide-ranging forms of environmental degradation and social disruption that had already circled the planet for two thousand years. To get at the gold, miners used hydraulic mining techniques that blasted away the Sierra foothills, flushed debris into streams and rivers, and destroyed aquatic and riparian habitat for all kinds of aquatic and terrestrial creatures. Hydraulic mines consumed vast quantities of timber for flumes and sluices, denuding mountainsides for tens of miles around every mining district. Lining those flumes and sluices was mercury, which amalgamated the gold while poisoning water supplies for fish, livestock, and people. By the 1860s, hydraulic mining in the California goldfields was consuming one million pounds of mercury annually – all of it dumped into streams, rivers, and nearby soils where it transformed into methylmercury, and diffused throughout the greater Sierra ecosystem.54
Quantifying blue carbon for the largest salt marsh in southern British Columbia: implications for regional coastal management
Published in Coastal Engineering Journal, 2021
Maija Gailis, Karen Elizabeth Kohfeld, Marlow G. Pellatt, Deborah Carlson
Despite historical modification of the marsh, the western portion of the Boundary Bay marsh is growing (Figure 5). Marsh expansion is a rare event in coastal marshes and is usually due to anthropogenic land changes and accumulation of debris from hydraulic mining (Watson 2008). Kellerhals and Murray (1969) hypothesized that western Boundary Bay marsh is prograding in response to tidal influence, sedimentation and vegetation growth, and ecological interactions that influence the growth of hummocks and eventual cohesion with the marsh. They surmised that the large quantities of eelgrass and algae are rafted onto hummocks and then covered with sand from strong winter storms. The new relief is then colonized with blue-green algal mats which then allow for typical sediment trapping and eventual halophyte propagation. The farthest western portion of the marsh contains a large beach ridge that was not present in the 1930s (Figure 5 and A6) (Engels and Roberts 2005). The area contained large logs and flotsam that blocked a large channel and has since been overgrown by vegetation (Kellerhalls and Murray 1969).