Study On Environmental Impacts Of Mining-Transport-Discarding-Reclaiming Stages In An Large Opencast Coal Mine Based On Life Cycle Assessment Theory

Most large-scale open-cast mines in China are in arid and semi-arid ecologically fragile zones.Open-pit mining destroys and occupies a large amount of land.The international reclamation rate of mines has reached 60%,which is much higher than the level of reclamation in China.At the same time,environmental pollution problems such as air pollution,water pollution and solid waste pollution will occur in the stages of mining-transport-discarding-reclaiming.Nowadays,most researches focus on a special stage of mining and utilization,and it is impossible to comprehensively and systematically reflect the environmental impact of man-made activities at various stages.Life Cycle Assessment(LCA)is an effective environmental management tool,our research combined the environmental impact of open-cast mining and land reclamation,the suitability evaluation of land reclamation,the resource consumption cost and the external environmental cost analysis in mining area to construct the entire life cycle assessment system,including“peeling-transport-stacking-engineering measures-biochemical measures”.The study area was located in Anjialing open-cast mine,we quantitatively analyzed the environmental load of each environmental type in each stage and the degree of environmental impact on the whole life cycle.Our results identified major environmental problems and proposed corresponding environmental improvement measures.Our research suggested that:(1)Applying the life cycle assessment theory,the cycle stages of“peeling-transport-stacking-engineering measures-biochemical measures”in the open-cast mine was reasonably divided,and the framework of its evaluation was constructed.The rationality and scientificity of the framework system were verified by case analysis.(2)The main types of environmental impacts in the mining-transport-discarding-reclaiming stages of mining areas included:resource consumption,global warming,health hazards,acidification,eutrophication,photochemical ozone synthesis,smoke and dust,solid waste.Among them,the smoke and dust had the hugest impact on the environment.During the life cycle stages of stripping,transportation,stacking,engineering measures,and biochemical measures,the stage that had the greatest impact on the environment was the stripping stage.(3)An example of land reclamation in Anjialing open-pit coal mine showed that in the life cycle of mining-transport-discarding-reclaiming stages,the most important stage of environmental impact was the stripping stage,with a contribution rate of50.24%,followed by transportation,with a contribution rate of 45.54%.Among the environmental impact types,the environmental impact of smoke and dust was the largest,with a contribution rate of 29.66%,followed by eutrophication with a contribution rate of 25.18%.After implementing certain improvement measures,the environmental impact load was 1.01×10~4/km~2 in the open-cast mine reclaiming life cycle,which was 19.2%lower than no implementation measures(1.25×10~4/km~2).Our research about entire life cycle assessment system in mining-transport-discarding-reclaiming stages can provide some supplements and references for related fields.