酸性矿山废水形成过程:来自反应运移模拟与同位素的启示  

The Generation of Acid Mine Drainage:Insights from Reactive Transport Modeling and Stable Isotope

作　　者：邱文杰 杜卓然 尹子悦 孙媛媛[1] 祝晓彬[1] 吴剑锋[1] QIU Wenjie;DU Zhuoran;YIN Ziyue;SUN Yuanyuan;ZHU Xiaobin;WU Jianfeng(School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学地球科学与工程学院,南京210023

出　　处：《高校地质学报》2025年第1期1-13,共13页Geological Journal of China Universities

基　　金：国家重点研发计划项目(2022YFC3702200);国家自然科学基金项目(U2167212)联合资助。

摘　　要：采矿活动形成的酸性矿山废水(AMD)是世界范围内的环境问题,研究AMD的产酸机制及影响重金属和硫酸盐的释放、迁移和转化等的生物地球化学过程,能够为定量预测AMD的形成过程与修复方案提供科学依据。文章基于TOUGHREACT/EOS3程序构建水—气二相流的多组分反应运移模型,模拟尾矿堆中硫化物矿物(如黄铁矿)在大气降水和氧气作用下的氧化溶解产酸过程。同时,进一步考虑相关组分在含水介质中迁移转化的物理和地球化学反应过程,反应网络包括硫化物矿物氧化溶解释放的H+、铁离子以及硫酸根迁移转化过程,主要矿物的溶解和沉淀反应引起pH缓冲过程。最后,将硫稳定同位素考虑到反应运移模型中,以识别AMD形成过程中发生的细菌硫酸盐还原过程及相应的硫同位素分馏。模型首先定量得出黄铁矿在不同氧化途径下的产酸贡献,结果表明同时考虑O_(2)(aq)和Fe^(3+)的平行氧化过程会增加产酸、铁离子和硫酸根浓度,pH受黄铁矿氧化释放的H⁺以及矿物溶解—沉淀对应的中和反应控制。稳定同位素反应运移模型结果表明,在不同分馏动力学富集系数下,δ^(34)S值变化差异较大,在开放系统中采用瑞利分馏模型则很大程度上会高估富集系数。该研究有利于理解并预测矿山环境中酸性水的形成与迁移过程,对于防治采矿活动引起的环境污染问题具有重要意义。Acid mine drainage(AMD)resulting from mining activities is a global environmental issue.Investigating the acid generation mechanisms of AMD and the biogeochemical processes affecting the release,migration,and transformation of heavy metals and sulfates provides a scientific basis for quantitatively predicting AMD formation and developing remediation strategies.In this paper,a multiphase reactive transport model for water-gas two-phase flow is constructed based on the TOUGHREACT/EOS3 code to simulate the acid generation process of sulfide minerals(such as pyrite)in tailings impoundment under the influence of atmospheric precipitation and oxygen.It further considers the physical and geochemical reaction processes of associated species in the migration and transformation within the aqueous medium.The reaction network includes the release of H⁺from the oxidation and dissolution of sulfide minerals,the migration and transformation of iron ions and sulfate,and the pH buffering processes caused by the dissolution and precipitation of major minerals.Finally,by incorporating sulfur stable isotopes into the reactive transport model,the study identifies the bacterial sulfate reduction processes and corresponding sulfur isotope fractionation occurring during the formation of AMD.The model quantitatively assesses the acid production contributions under different oxidation pathways of pyrite,revealing that simultaneously considering the parallel oxidation processes of O_(2)(aq)and Fe^(3+)increases the concentrations of acid,iron ions and sulfate.The pH is controlled by the release of H⁺from pyrite oxidation and the neutralization reactions corresponding to mineral dissolution and precipitation.Stable isotope reactive transport model indicates significant differences inδ^(34)S values under different fractionation kinetic enrichment factor,and using the Rayleigh fractionation model in an open system can greatly overestimate the enrichment factor.This research aids in understanding and predicting the formation and migration

关 键 词：酸性矿山废水 水—气二相流 反应运移模拟 硫稳定同位素 

分 类 号：P641[天文地球—地质矿产勘探]