1、翻译部分英文原文Application of Paste Backfill in Underground Coal FiresCarsten Drebenstedt1 and Manoon Masniyom21 Technische Universitt Bergakademie Freiberg, Germany2 Prince of Songkla University, ThailandAbstract: Coal fires are known from different coalfields worldwide. China, India, USA, Australia, Indo
2、nesia and South Africa are the main countries affected by coal fires. The fires is thermally intensive and cause numerous sinkholes, large-scale subsidence, air pollution, global warming, loss of mining productivity and increasing safety risk. The Wuda Inner Mongolia coalfield has been selected as a
3、 possible test area for paste backfill. The traditional methods, executed by fire fighting teams, by covering the coal fire areas with soil, blasting burning coal outcrops and injecting water in the subsurface fire pockets are continuously improved and extended. Initiatives to introduce modern techn
4、iques, such as backfill placement at fracture and borehole, to cool down the burning coal and cut off the air supply. This study is to investigate backfill materials and techniques suited for underground coal fires. Laboratory tests were carried out on physical, chemical and mechanical properties of
5、 different backfill materials and mixtures thereof. Special attention was paid to materials generated as by-products and other cheaply available materials e.g. fly ash from power plants. There is a good chance that one of the different material mixtures investigated can be used as a technically and
6、economically viable backfill for underground coal fires.Keywords: Coal fire, backfill materials, paste backfill and fly ash1. IntroductionCoal fires are known from different coalfields worldwide. China, India, USA, Australia, Indonesia and South Africa are the main countries affected by coal fires.
7、Normally, the mineworkers and the people living in the surrounding area are affected by large amounts of aerosols and toxic gases, like carbon monoxide or sulphur oxides. But also greenhouse relevant gasses are being released in large amounts and affect the environment. Additional hazards include la
8、nd-subsidence, contamination of drinking water and damage of flora and fauna around the fires. Protecting the economically valuable coal resources and the environment is of great relevance on a national and international level (Jing et al, 2005).Enormous resources of coal are present in China. Coal
9、is one of the most important contributors to the development of the national economy. China is the largest exporter of coal in the world. However, many coal mines in China are seriously endangered by coal fire (Kuenzer, 2007). These fires occur within a region that stretches over 5,000 km east to we
10、st and 750 km north to south (Fig. 1). About 100-200 million tons of coal is being lost because of coal fires each year. The main regions in China effected by coalfield fires are: Xinjiang, Gansu, Qinghai, Ningxia, Shaanxi, Shanxi, Wuda Inner Mongolia, Sichuan, Chongqing and Fujian. The Wuda Inner M
11、ongolia coalfield is located NE of the Helan Mountain range in a desertlike environment with elevations ranging between 1,100 and 1,300 m msl. The coal layers of the Wuda coalfield belong to the Upper Carboniferous and Lower Permian Taiyuan and Shanxi Formation. The coal bearing strata was deposited
12、 in marine near coastal swamps. 24 coal seams with a thickness of 0.2 m to 6 m are exposed in a 10 km long and 4 km wide N-S striking syncline. The coal quality is in the range of medium volatile bituminous coal. The surface of the Wuda coalfield is strongly mined and mainly covered by sandstones or
13、 loose sand. Coal fires affect an area of 280,000 m2. Most coal fires occur underground and can be related to small-scale mining operations. These fires is thermally intensive and cause numerous sinkholes, large-scale subsidence, air pollution, global warming, loss of mining productivity and increas
14、ing safety risk. Currently there are 3 underground coal mines in Wuda (Huang Baici, Su Haitu and Wu Hushan).Figure 1: Localization of coal fires in China (Jing, 2005)2. Paste backfillFirst used at the Grund Mine in Germany during the 1980s, paste backfill is a uniform, low permeability, generally co
15、nsisting of high solids density mixture with about 15% minus 45 m (325 mesh) fines content (Potvin, 2005). Due to compaction, paste backfills constituent particles do not settle out of suspension at zero flow rates with the fine particles of the matrix forming an annulus around a plug of coarser par
16、ticles to act as a form of lubrication thereby greatly reducing pipeline frictional resistance (Fig. 2). Figure 2: Paste backfill (Potvin, 2005)Slurry backfill requires considerable transport water to flush it through the underground backfill distribution system and deliver the alluvial sand or tailing solids to a stope. Such excess transport water must be drained from the stope and hence, fine particles are
