Study On Mechanism Of Local Heavy Metal Pollution Caused By Sewage Wind Emission Of Lead-zinc Mine

With the development of economy and human society, the role of non-ferrous metal mine is more and more important. The world exploitation and consumption quantity of lead and zinc is increasing year by year. Problems will be caused in the process of exploitation and utilization of lead-zinc mine and the heavy metal pollution is more prominent. The dust containing heavy metal which migrate to the surrounding environment would pollute and would do harm to human health and safety in the process of the underground non-ferrous metal mining. This paper studied the mechanism of local heavy metal pollution caused by sewage wind emission of lead-zinc mine and also studied heavy metal pollution of soil that nearby exhausted ventilation shaft of a lead-zinc mine of Hunan.This paper used the method of literature retrieval and statistical analysis to summarize systematically the research status of heavy metal pollution of non-ferrous at home and abroad. The method of deductive analysis was used to analysis pollution migration influence factor of dust contained with heavy metals by the exhausted ventilation shaft in lead-zinc metal mine and77basic elements were obtained. In order to show the complex relation among every basic element, the fishbone diagram was used. Analytic hierarchy process was used in obtain the sort of structural importance of each basic event. To ensure the sort of structural importance of each basic event was correct factor analysis method was used and the two calculation results were analyzed comparatively. It shows that the results of analysis object of those two methods were uniform. One lead-zinc mine of Hunan was chosen to study heavy metal pollution of soil that nearby its exhausted ventilation shaft. Linear regression models of Zn and Pb that soil contains were obtained. Then fault tree analysis method was applied to sort structural importance of heavy metal pollution migration influence factors of Hunan lead-zinc mine. Based on the calculate results, some heavy metal pollution migration intervention approaches were put forward. The main research and conclusions in this paper are as follows:(1) To analyze the influencing factors of pollution migration of dust contained heavy metals by the exhausted shaft in non-ferrous metal mines systematically, pollution transfer media was divided into three areas, i.e. air, soil and water. Then listed influence factors that related knowledge of meteorology and agrology etc. were combined and77basic elements were obtained such as dust concentration, air humidity, free air temperature, air velocity and wind direction etc.(2)Based on dust movement rule, there were three main causes that caused local air pollution, they were dust contained heavy metal discharged from exhausted ventilation shaft, dust contained heavy metal discharged spread in the air and property of heavy metal in dust. Dust contained heavy metal settled on the soil and migrated and spread in the soil were main reasons that caused local soil pollution. Dust contained heavy metal settled on water and migrated and spread in water were main reasons that caused local water pollution. Based on these analysis and combined with analysis thought of deductive method, the fishbone diagram was used to show the complex relation among every basic element.(3)AHP was used to get the sort of structural importance of77basic events. The importance degree of heavy metal content, wind speed, the toxicity of heavy metal in dust, wind direction and air exhausting quantity were the top five, and the last five were soil texture, interaction among soil colloids, soil bulk density, heavy metal ion radius, soil parent material and vegetation condition.(4)Dates were input to factor analysis method calculation software and15dates were filtered. The comprehensive score of61preserving basic elements was matched with the result of AHP. This illustrated that AHP and factor analysis method both can be used for study influencing factors of pollution migration of dust contained heavy metals by the exhausted shaft in lead-zinc mines.(5) Linear regression models of Zn and Pb according to heavy metal content in soil around exhausted ventilation shaft of Hunan. In order to analyze basic elements quantitatively, fault tree analysis method was applied and some heavy metal pollution migration intervention approaches were proposed.