Small Underground Mines
Need Special Equipment
By: Maurice Deul
This country is blessed with abundant coal resources that are readily accessible by current mining methods. That does not mean that we should be profligate with our mineral wealth by increasing reliance on the highly productive large underground coal mines that use longwall mining methods.
The number of small underground coal mines is decreasing as the trend towards ever larger longwall mines continues. Such mines are important to maintaining a moderating effect on production during rising and declining markets. Small mines can shut down much more easily during a market decline and reopen quickly to meet peak demands for coal. But small mines play a much more important role: they can mine coal from reserves that cannot be recovered by longwall mining.
Any keen observer of the recent trends in the development of mining equipment could comment that the industry’s motto might be “If we can’t make it better make it bigger.” We now have continuous mining machines so large and so overpowered that they have a productive capacity of 15 tons per minute and more: all for a mining system where a production of 800 tons per eight-hour shift is attained only rarely. Most small mines are outfitted with used and reconditioned mining equipment originally owned by larger mines and the availability of these machines dictates the infrastructure needed to operate such equipment: the power supply, the transformers and cable. These small mines don’t need such oversize equipment, but usually only that is available.
The recent decline in the number of small underground mines is show in Table 1 where data for the years 1980 and 2000 are compared. Although the total number of mines had decreased by 72 percent total coal production increased by 12 percent. The largest increase was in the largest of the small mines, probably those that could make better use of the available machinery.
1 to 4
5 to 9
10 to 19
20 to 34
35 to 49
|Table 1. Coal Production From Small Underground Mines (>50 Miners) Comparing 1980 With 2000 (Data provided by MSHA, Denver Office)|
The nearly 77 million tons extracted by the 605 small mines in the year 2000 represents 21 percent of all underground coal production. In 1980 the nearly 69 million tons of coal produced by 2165 small underground mines represented 20.4 percent of total underground coal production, an almost identical percentage as in the year 2000. This is a sector of the market that should be encouraged to grow because future deep mining using longwall equipment will result in ever more reserves that cannot be mined effectively except by room and pillar methods.
Table 2 shows a different trend: there were even fewer mines operating during 2002 (-11%) and average production per mine decreased (-19%) as compared with 2000. These small mines accounted for only 17.5 percent of total underground production. This is clearly due to reduced demand for coal during the recession (an ugly term) and is an indicator of the sensitivity of these small mines to market demand for coal.
Table 2. Production From Small Underground Mines 2002
I believe that small mines in order to prosper need new equipment that is not now available from mining machinery manufacturers. Ideally such equipment, including continuous miners, loaders, shuttle cars and roof bolters should be diesel-powered thus eliminating the need for a costly high-voltage electric distribution system. This will require a radical change in the current market trend towards even bigger mining equipment for fewer but larger mines. It is questionable that a complete small-scale compatible electrical system for these special needs would be affordable.
With the need for small mines to assure recovery of mineable coal from relatively small reserve acreage adjacent to larger longwall mines it is imperative that suitable mine machinery will be available for this developing market.
Will American machinery manufacturers satisfy this need or will this be a niche that will be filled by foreign factories?
Will the National Mining Association support such an effort or will we need to await the resurrection of the US Bureau of Mines? cl
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