Dynamic Anlysis On Environmental Quallity Of Main River In The Dexing Copper Mine From 2002 To 2017

Dexing Copper Mine is located in Dexing City,north of Shangrao City,Jiangxi Province.It is the largest copper mine in Asia.At present,it has formed the capacity to deal with 130,000 tons per day.It is open-pit mining,flotation enrichment of copper concentrate,heap leaching to produce electrolytic copper.The mine is the first national green mine in China to pass the acceptance test.Previous studies on the mine environment of Dexing Copper Mine have been rich,but the dynamic changes of the mine water environment quality after 2012 have not been studied.This paper collects and collates the data of surface water and groundwater of major rivers(Dawu River and 4~#Tailings reservoir and downstream)in 2002,2004,2011 and 2012,collects and tests samples in 2017,compares the dynamic change characteristics of water environment quality of main rivers in Dexing Copper Mining Area from 2002 to 2017,and studies the reasons for the change.Suggestions and suggestions for water environment protection in Dexing Copper Mine are put forward.The achievements are as follows:1.The surface water pH value of the Dawu River Basin decreases from upstream to downstream,and the acidification of the Dawu River is concentrated in the middle and lower reaches.Except for the source area,the water quality of Dawu River meets the safety standard,and the excessive heavy metals are no longer the main pollution problem of Dawu River.Groundwater is not affected by mining,and the pH value and heavy metal content meet safety standards.In 2004,2011 and 2012,the average value of surface water pH value from upstream to downstream of Dawu River is less than 6.Most heavy metal elements are high in the main stream of mining area.In 2017,the water quality from upstream to downstream is better than before.2.The pH value of the 4~#Tailings reservoir and its downstream surface water is between 6.88 and 7.13,and the pH value and the heavy metal content is in line with the national water standard of Class III.The pH value of surface water from 2002 to2012 is between 6.4 and 9.3,and the content of heavy metals is not exceeding the standard.3.Through the analysis of pH value and heavy metal element content in different periods,it is found that the change trend of pH value and some element content in upstream and middle reaches of water is the same.The changing trend of water in the middle and lower reaches is the same.The reason for the improvement of water quality in 2017 is that the quality of water environment is obviously better through the construction of green mines,specifically:(1)there is no external discharge in the recovery and utilization of acid reservoir water.Therefore,it does not have an impact on the external environment;(2)the normal application of acid and alkali wastewater neutralization treatment station makes there is no sewage discharge,(3)the river course of Dawu River is cleared and silted in time,so that the heavy metals in the sediment of the riverbed are obviously reduced,and the heavy metals in the sediment of the river bed are obviously reduced.It is suggested that Dexing Copper Mine should continue to protect the water environment in accordance with the requirements of green mines,pay attention to the treatment of domestic sewage,and clear the river silt in time.