Arsenic Release From Waste Rock And Tailings Of Gold Mines In Water Environment

In recent years,the environmental problems caused by the waste rock and tailings produced in the mining of gold mines have become more frequent.The gold mines are usually accompanied by a large amount of arsenic,causing serious pollution problems when entering the water environment,affecting the health of people around the mining area and causing loss of life and property.Current research by researchers has focused on arsenic release and its bioavailability..There are many gold mines in Gansu Province,and the resulting arsenic environment may be more serious.The paper uses a combination of arsenic release and the identification of solid waste attributes.The release of arsenic in the water environment from waste rock and tailings of Huatai Gold Mine in Min County and tailings of Haotian Gold Mine in Min County as studied.In this dissertation,X-ray diffraction and X-fluorescence spectrometry techniques were used to analyze the three phases of the samples.The existence of arsenic in the samples was analyzed by Tessier’s five-step extraction method.The data shows that the main substances in the three samples are compounds of silicon,aluminum,iron and calcium,of which the silicon content is the highest.The content of arsenic in waste rock and tailings of Min County is0.07%,and the content of arsenic in tailings of Kang County is 0.02%.The presence of arsenic in the sample was analyzed μsing Tessier’s five-step extraction method.The arsenic content in the residμe was highest in all three samples.The residual arsenic content in waste rock and tailings in Min Coμnty reached more than 90%,while the residual arsenic content in tailings in Kang Coμnty was 66.75%.The more easily released arsenic in exchange-state arsenic,carbonate-bound arsenic,and Fe-Mn oxide-bound arsenic,accounted for aboμt 10% and 6%of the total waste rock and tailings in Min County,respectively,in Kang County.The proportion of tailings is relatively higher,which is 22.95%.A solid waste toxicity leaching experiment was performed on three samples,and the flip oscillation method was compared with the horizontal oscillation method.The results show that:the concentration of arsenic in the three kinds of samples leached by using the horizontal oscillation method is higher than the concentration of arsenic leached by the inversion oscillation method.In the horizontal oscillation method,the arsenic concentration reached a maximum of 111.98 μg/L at the 36 th hoμr sampling of the waste rock in Min County.Both kinds of tailings had arsenic concentration at the 18 th hour.The maximum value of tailings was 177.36μg/L,and the maximum concentration of arsenic in Kang County was 41.85μg/L.It can be judged that the leaching toxicity of arsenic μsing the horizontal oscillation method is stronger than that of the arsenic used in the inversion oscillation method.Because in the identification of solid waste attributes,the limit of arsenic in the horizontal method is 0.5mg/L,and the limit of arsenic in the inversion method is 5 mg/L,all data are beyond the limits of the two methods.The release rule of arsenic in samples at different pH,different temperatures,and different particle sizes was studied.The results show that:(1)In the range of pH 3.5 to 8.5,the concentration of arsenic in the three samples gradually increased.In the first sampling,the concentration of arsenic in the waste rock reached its maximum value:The concentration of arsenic in the solution of pH=8.5 was 232.92μg/L.The arsenic content in the tailings of two kinds of tailings is higher,so the leaching concentration is higher.The maximum valμe is396.72μg/L at the third sampling pH=8.5.The concentration of arsenic in the two kinds of tailings was gradually decreased in the sample after the three samples reached the maximum value,and the concentration of arsenic leaching stabilized after two months of the experiment.(2)In the range of 0℃ to 40℃,the concentration of arsenic in the three samples increased with increasing temperature.The maximum leaching concentration of arsenic was the arsenic concentration of 272.05μg/L at 40°C for the third sampling of the waste rock in Jixian County.(3)In the range of 6 mesh to 100 mesh,arsenic releases the largest amount of arsenic in water from 20 to 40 mesh,and the maximum value is 71.72μg/L.(4)Through experimental data analysis and comparison,the factors affecting arsenic release are: pH>temperature> particle size.The results of leaching test of waste rock in Gongxian County and Kangxian tailings show that:the dissolution of arsenic from waste rock was mainly high in the first three weeks and then decreased slightly every week.The tailings had more dissolution of the first five arsenic,and the amount of arsenic released decreased significantly in the last three weeks.In general,the lower the pH of the leachate,the smaller the arsenic elution;the pH of the leachate after filtration is neutral and alkaline.