摘要
为掌握锰矿开采产生的锰矸石向环境中排放汞状况,以某大型锰矿开采企业的锰矸石为研究对象,开展锰矸石中汞的静态浸泡和动态淋溶特征研究.静态浸泡实验分别考察不同粒径(6-20目、20-100 目、大于 100 目)、pH 值(4.0、4.8、5.6),浸泡时间(10-180 min)、固液比(1∶16、1∶8、1∶5.3、1∶4、1∶3.3、1∶2.7)、温度(25、35、45 ℃)对锰矸石中汞溶出特征影响.动态淋溶实验采取在淋溶柱内分别装入6-20目、20-100目,以及大于6目混合锰矸石样品各300g,温度为25℃,以1.0mL·min-1淋溶速度,每间隔24h连续加模拟酸雨(pH为4.0)进行淋溶实验,共计反复淋滤38d.实验结果表明:在静态浸泡实验中,锰矸石中汞的浸出量随浸泡时间增加而增加,固液比越小,浸出量越大;温度升高,浸出量增大.酸性条件有利于增加锰矸石中汞的迁移性,粒径较小的锰矸石拥有更大的比表面积,与浸泡溶液的接触面积越大,锰矸石中汞更易于溶解析出.固液比为1∶2.7时,不同粒径锰矸石中汞浸出量均为最大,表明较大的降雨量和积水量可能增加锰矸石中汞的溶出释放风险.在动态淋溶实验中,不同粒径锰矸石中淋溶汞浓度变化显著,且均在13-38 d时间范围内,呈逐渐变小的相似释放规律;淋溶后的溶液均呈现酸度增大.通过估算,每年每吨锰矸石尾矿大约溶出汞量为375.9mg,锰矿原矿开采人为活动过程均会向环境中排放大量的汞.
Abstract
To investigate the mercury emission of manganese gangue produced by manganese ore mining to the environment,this thesis was based on the research on the static immersion and dynamic leaching characteristics of manganese gangue from a large manganese mining enterprise.In static immersion experiments,the effects of different particle sizes(6-20 mesh,20-100 mesh,greater than 100 mesh),pH value(4.0,4.8,5.6),immersion time(10-180 min),solid-liquid ratio(1∶16,1∶8,1∶5.3,1∶4,1∶3.3,1∶2.7)and temperature(25,35,45 ℃)on the dissolution characteristics of mercury in manganite were investigated respectively.The dynamic leaching experiment was performed by loading 300 g of manganese gangue samples with 6-20 mesh,20-100 mesh and the mixed sample with more than 6 mesh in the leaching column at a temperature of 25 ℃ under a leaching rate of 1.0 mL·min-1,and continuously adding simulated acid rain(pH 4.0)every 24 h,for a total of 38 days of repeated leaching.The results showed that in the static immersion experiment,the leaching amount of mercury in manganese gangue increased with the increasing immersion time,and the leaching amount increased with smaller solid-liquid ratio and higher temperature.Acidic conditions were conducive to increasing the mobility of mercury in manganese.Manganese gangue with smaller particle size had a larger specific surface area,and the larger the contact area with the immersion solution,the easier it was for the mercury in the manganese gangue to dissolve and desorb.At a solid-liquid ratio of 1∶2.7,the amount of mercury leached from manganese gangue with different particle sizes was the largest,indicating that heavy rainfall and water accumulation may increase the risk of mercury dissolution and release from manganese gangue.In the dynamic leaching experiment,the concentration of leached mercury in manganese gangue of different particle sizes changed significantly,showing a similar gradually decreasing release within 13-38 d.After leaching,the solution showed increased acidity.It is estimated that the amount of mercury dissolved per ton of manganese gangue tailings per year is about 375.9 mg,and large amounts of mercury will be released into the environment during manganese raw ore mining.
基金项目
国家自然科学基金(41877384)
重庆市教委科学技术研究计划(KJQN202104501)
NETL
NSTL
万方数据