降雨pH对煤矸石中重金属和SO■释放行为的影响

以高硫煤矸石为研究对象，采用静态淋溶试验探究在模拟降雨pH分别为2、3、5、7的条件下，煤矸石中重金属Mn、Cu、Zn和SO■的释放规律及动力学行为。结果表明，酸性条件更有利于重金属和SO■释放，随时间增加表现为先快速释放后逐渐稳定的趋势。在降雨pH为3时，重金属Mn、Cu、Zn的累积释放量最大，分别达到60.40、29.11、5.86 mg/kg。在降雨pH为2时，SO■的累积释放量最大，达到了25 027.27 mg/kg。动力学结果表明，重金属释放由界面化学反应控制，而SO■由固体膜层界面和扩散混合控制，且在重金属与SO■释放的过程中产生大量H⁺,使淋出液pH<1.52。本研究结果可以从污染物源头释放的角度为煤矸石堆场重金属及SO■污染防控和监管提供理论依据。

Effect of Rainfall pH Value on Release Behavior of Heavy Metals and SO42- from Coal Gangue

The release rules and kinetic behaviors of heavy metals (Mn, Cu, Zn) and SO42- from coal gangue were investigated under the conditions of simulated rainfall pH value of 2, 3, 5 and 7 respectively using static leaching test with high sulfur coal gangue as the research object. The results show that the acidic conditions are more favorable for the release of heavy metals and SO42-, which shows a trend of rapid release followed by gradual stabilization with increasing of time. The cumulative release of Mn, Cu and Zn is the highest at rainfall pH value of 3, reaching 60.40, 29.11 and 5.86 mg/kg, respectively. The cumulative release of SO42- is biggest at the precipitation pH value of 2, reaching 25 027.27 mg/kg. The kinetics results show that heavy metals release is controlled by interfacial chemical reactions, while SO42- is controlled by interfacial and diffusive mixing of solid film layers, and a large amount of H+ is generated during the release of heavy metals and SO42-, which makes the leachate pH<1.52. The results of this study can provide a theoretical basis for heavy metals and SO42- pollution prevention, control, and regulation in coal gangue dumps from the perspective of pollutant release at source.