新型钝化剂与秸秆对黄铁矿的氧化抑制效果

尾矿中硫化矿物氧化产生的酸性矿山废水（AMD）,因pH低和富含重金属离子而对周边生态环境造成巨大危害。黄铁矿作为尾矿中分布最广、含量最高的常见硫化矿物之一,其氧化是酸性矿山废水产生的一个重要因素。因此如何有效的从源头控制黄铁矿的氧化是治理AMD的根本途径。实验以黄铁矿为研究对象,合成了一种新型的钝化剂——二硫代胺基甲酸钠（DTC-TETA）,并将该钝化剂与芦苇秸秆结合,分别考察了钝化剂和钝化剂-秸秆混合物抑制黄铁矿在酸性溶液中氧化的效果。结果显示：氧化24 h后,单纯的秸秆粉末覆盖对黄铁矿氧化抑制效果并不理想;0.5%（V/V）DTC-TETA对黄铁矿氧化抑制率为59.5%,0.5%（V/V）DTC-TET和秸秆混合物可以使黄铁矿氧化抑制率增加至76.9%。可见在减少钝化剂浓度的情况下,合理的添加秸秆物质,不仅能有效的抑制黄铁矿的氧化,而且从源头上减少了化学物质的使用量,同时还充分利用了农业废弃物,从而降低钝化成本和可能的环境风险。     

生物氧化磁黄铁矿产生铁离子

从广东云浮矿山酸性废水中富集获得氧化亚铁硫杆菌(Thiobacillus ferrooxidans),利用该氧化亚铁硫杆菌研究了反应时间、pH、温度、矿浆浓度和矿物粒度对磁黄铁矿生物氧化获得铁离子的影响。结果表明,在29℃,摇床转速200 r/min,10%接种量条件下,氧化亚铁硫杆菌可以明显促进磁黄铁矿的氧化,但反应后期有黄钾铁矾沉淀生成,不利于获得铁离子;控制溶液pH值为2.00,温度在29～36℃范围,可促进生物氧化磁黄铁矿获得铁离子;铁离子量随着矿浆浓度的增大和矿物粒度的减小而增加,优化的矿浆浓度和矿物粒径分别为6%和58μm左右。     

硫酸盐还原菌和酸性矿山废水的生物处理

本文论述了硫酸盐还原菌的代谢和所需要的碳源以及硫酸盐还原的影响因素和生物处理酸性矿山废水的研究进展。     

碳酸盐岩煅烧改性处理酸性矿山废水的研究

将碳酸盐岩在不同温度下进行煅烧改性,在保持颗粒机械强度的条件下将其应用于酸性矿山废水(AMD)的处理。结果表明,碳酸盐岩在600℃下煅烧基本不产生变化,当升至750℃时,碳酸盐岩开始分解,煅烧3.0h后,烧失量为1.86%,煅烧后产物仍保持较强颗粒强度。800℃以上煅烧的碳酸盐岩则出现颗粒断裂现象,放入AMD中会立即溶解产生白色沉淀。在750℃煅烧改性后的碳酸盐岩能有效提高AMD的pH,对各种金属离子都有非常好的去除效果,尤其克服了原岩对Mn2+去除效果不佳的缺点;将750℃煅烧改性后的碳酸盐岩应用到野外AMD处理工程中,能有效减少处理构筑物的体积和占地面积,从而降低建设成本。     

硫化沉淀法处理矿山酸性废水研究

对沉淀浮选机理进行了分析，讨论了选择性沉淀一浮选技术，论述了硫化沉淀浮选法不仅能处理矿山含重金属离子废水，同时还能回收其中的有用金属。     

SAPS处理酸性矿山废水的模拟应用研究

根据硫酸盐还原菌(SRB)的生物矿化原理设计了一套连续碱度产生系统(SAPS)反应器,以市政污水处理厂的活性污泥为SRB提供源,南方常见的香芋柄为有机物碳源,选用石灰石为反应器中碱度层填充物,进行实验室模拟SAPS处理酸性矿山废水(AMD)的应用研究,实验结果表明,SAPS处理酸性矿山废水的方法是具有技术可行的:SRB利用有机碳源生长代谢,产生碱度、还原SO42-和降解COD。最终废水pH从进水4.0左右上升到出水7.0左右;出水COD降低到约200 mg/L; SO42-还原为各种硫化物,其还原率约为61%;不同金属离子在有机层和碱度层发生反应产生沉淀,其中Fe2+、Cu2+和Zn2+的去除效率分别约为76%、78.5%和82%,而主要靠物理吸附作用的Mn2+去除率较低;初次模拟SAPS运行到56 d时,系统最终因有机碳源不足而各项指标不再改变。     

硫酸盐还原菌和酸性矿山废水的生物处理

本文论述了硫酸盐还原菌的代谢和所需要的碳源以及硫酸盐还原的影响因素和生物处理酸性矿山废水的研究进展.     

Fenton氧化/高浓度泥浆法处理矿山废水

为了解决某大型铜矿废水COD不达标问题,采用Fenton氧化对原有高浓度泥浆（HDS）工艺进行改进。探讨了Fenton氧化矿山废水各指标的去除效果以及H₂O₂浓度对出水COD去除效果的影响,结果表明,Fenton氧化-电石乳中和絮凝沉淀工艺处理矿山废水是可行的,最优实验条件为：pH稳定在3.0～4.5,H₂O₂投加量0.5 mL/L,电石乳投加量8.5 g/L,PAM投加量1.5 mg/L;系统对废水COD的去除机理是加入的H₂O₂和矿山酸性废水中的Fe²⁺离子在低pH下形成Fenton试剂;系统对TFe、Zn²⁺、Cu2+ 的去除效果比Mn²⁺的去除效果更稳定。     

膨润土复合颗粒与SRB协同处理酸性矿山废水

针对酸性矿山废水（AMD）pH低、重金属含量大、处理难等问题,采用膨润土-钢渣复合颗粒吸附剂、塑料雪花片和碎石作为填料,经生活污水、鸡粪、锯末发酵液驯化的硫酸盐还原菌（SRB）优势菌悬液对填料进行挂膜,构造三组动态柱：I#动态柱采用分层填装方式、II#动态柱采用混合填装方式、III#动态柱为只含有微生物的动态柱。研究其对Fe2+、Mn2+、Cu2+、Zn2+、SO42-和H+的去除效果,并研究分层的动态柱的再生效果、揭示机理。结果表明：膨润土-钢渣复合颗粒与微生物填料分层填装的方式更利于处理酸性矿山废水（AMD）,该动态柱40 d时对Fe2+、Mn2+、Cu2+和Zn2+的去除率均能达到95%以上,对SO42-的去除效果好于其他两个动态柱,且出水pH为中性,同时SRB还原SO42-生成的S2-/H2S可以使重金属离子固定、饱和吸附剂再生。说明膨润土复合颗粒与SRB协同处理酸性矿山废水具有创新高效性,值得推广使用。     

基于氧化还原-分步沉淀法的酸性矿山废水处理效果

为降低韶关市大宝山酸性矿山废水(AMD)的处理成本,采用氧化还原-分步沉淀法对矿山废水进行处理。结果表明：将石灰石分多次投入经过还原处理的废水中,在反应时间为45 min、转速为250 r·min⁻¹、废水pH为5时,可从AMD中回收高品质石膏;继续用NaOH溶液调节废水pH至5.5,控制曝气量为4 mg·L⁻¹,曝气时间为45 min,通过氧化沉淀法和铁氧体法可分步回收废水中的Fe^2+/3+,再向废水中加入NaOH溶液,调节废水pH至9.5,可沉淀回收废水中的Zn²⁺、Cu²⁺;经过该工艺处理后,废水中各金属离子均低于国家污水综合排放标准(GB 8978-1996);该工艺处理1 t废水,可回收石膏5.4 kg(纯度85.72%),铁渣1.53 kg(w(Fe)=35.4%)、锌铜渣1.4 kg(w(Zn)=10.89%、w(Cu)=0.1%);废水中Fe^2+/3+、Zn²⁺、Cu²⁺回收率分别为84.3%、71.2%、46.2%,废水处理的药剂成本为4.1元·t⁻¹,废水产生可回收资源产品收入为3.8 元·t⁻¹。该工艺可从AMD中回收高品质石膏并分步回收废水中的金属,有效降低废水的处理成本,回收废水中的资源,实现环保与经济效益双赢的目标,并为AMD资源化处理提供理论指导。     

甲壳生物质去除酸性矿坑水中镉的性能与机制

采用低成本、可持续修复材料处理酸性矿坑水 (acid mine drainage, AMD) 具有重要的科研价值和应用前景。选取基围虾、对虾、蛎虾和梭子蟹壳4种甲壳生物质,探究其对AMD模拟水样及恒定pH的AMD水样中镉的去除性能与机制。结果表明：甲壳生物质具有良好的镉去除能力 (112.38~235.45 mg·g⁻¹) ,其含有丰富的碳酸钙对镉去除起了至关重要的作用,可通过中和作用调高AMD的pH值,降低镉的迁移能力;也可与镉离子形成碳酸镉沉淀,促进镉的固定。此外,甲壳生物质中大量的羟基、羧基等官能团可通过络合作用捕获镉离子。研究结果为甲壳生物质的资源化利用和废弃矿山AMD的低成本、可持续修复提供了理论依据。     

Numerical simulations of pyrite oxidation and acid mine drainage in unsaturated waste rock piles

Numerical simulations of layered, sulphide-bearing unsaturated waste rock piles are presented to illustrate the effect of coupled processes on the generation of acid mine drainage (AMD). The conceptual 2D systems were simulated using the HYDRUS model for flow and the POLYMIN model for reactive transport. The simulations generated low-pH AMD which was buffered by sequential mineral dissolution and precipitation. Sulphide oxidation rates throughout the pile varied by about two orders of magnitude (0.004-0.4 kg m-3 year-1) due to small changes in moisture content and grain size. In the fine-grained layers, the high reactive surface area induced high oxidation rates, even though capillary forces kept the local moisture content relatively high. In waste rock piles with horizontal layers, most of the acidity discharged through vertical preferential flow channels while with inclined fine grained layers, capillary diversion channeled the AMD to the outer slope boundary, keeping the pile interior relatively dry. The simulation approach will be useful for helping evaluate design strategies for controlling AMD from waste rock.     

Neutralization/prevention of acid rock drainage using mixtures of alkaline by-products and sulfidic mine wastes

Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system’s neutralization potential. Leachates from 1 m³ tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH?<?2) with high concentrations of As (65 mg/L), Cu (6 mg/L), and Zn (150 mg/L) after 258 days. The leachate from water-saturated waste rock had lower concentrations of As and Cu (<2 μg/L), Pb and Zn (20 μg/L and 5 mg/L), respectively, and its pH was around 6. Crushed (<6 mm) waste rock mixed with different fractions (1–5 wt %) of green liquid dregs, fly ash, mesa lime, and argon oxygen decarburization (AOD) slag was leached on a small scale for 65 day, and showed near-neutral pH values, except for mixtures of waste rock with AOD slag and fly ash (5 % w/w) which were more basic (pH?>?9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation.     

国外尾矿酸性排水和重金属淋滤作用研究进展

尾矿引起的环境问题是水 气 矿物在地表条件下发生复杂反应的综合结果。近年来 ,国外学者研究显示 ,发生在尾矿中的风化作用不仅仅有硫化物的氧化作用 ,而且还伴随有机物氧化作用 ,碳酸盐等矿物中和作用 ,次生矿物沉淀作用、结晶作用、胶结作用 ,矿物交代蚀变作用、吸附作用、离子交换作用以及生物作用。上述各种作用互相影响 ,互相制约。目前 ,最新研究表明 ,许多因素都会影响尾矿风化作用 ,这些因素主要包括 :尾矿原生矿物组成、成因、化学成分、表面积和形态 ;尾矿酸中和潜力 ;溶液pH值 ;次生矿物形成及其吸附、离子交换、胶结作用 ;溶液中Fe3+离子的浓度 ;有机物的种类和含量 ;尾矿粒度分布和空隙度 ;气候条件和尾矿的水文地质环境     

A review on the mechanism,risk evaluation,and prevention of coal spontaneous combustion in China

In recent years, the ecology, security, and sustainable development of modern mines have become the theme of coal mine development worldwide. However, spontaneous combustion of coal under conditions of oxygen supply and automatic exothermic heating during coal mining lead to coalfield fires. Coal spontaneous combustion (CSC) causes huge economic losses and casualties, with the toxic and harmful gases produced during coal combustion not only polluting the working environment, but also causing great damage to the ecological environment. China is the world’s largest coal producer and consumer; however, coal production in Chinese mines is seriously threatened by the CSC risk. Because deep underground mining methods are commonly adopted in Chinese coal mines, coupling disasters are frequent in these mines with the coalfield fires becoming increasingly serious. Therefore, in this study, we analyzed the development mechanism of CSC. The CSC risk assessment was performed from the aspects of prediction, detection, and determination of the “dangerous area” in a coal mine (i.e., the area most susceptible to fire hazards). A new geophysical method for CSC determination is proposed and analyzed. Furthermore, the main methods for CSC fire prevention and control and their advantages and disadvantages are analyzed. To eventually construct CSC prevention and control integration system, future developmental direction of CSC was given from five aspects. Our results can present a reference for the development of CSC fire prevention and control technology and promote the protection of ecological environment in China.     

TiO2光催化氧化降解乳酸的工艺及机理研究

以TiO2为催化剂、紫外灯为光源对乳酸进行光催化降解实验,考察了乳酸初始浓度、TiO2用量、反应时间、曝气方式等因素对乳酸降解率的影响,并在此基础上应用正交实验对降解条件进行优化,同时对乳酸的降解机理进行了探索研究。实验结果表明：以300 W紫外汞灯为光源,在乳酸初始浓度为0.5 g/L、TiO2量为0.20 g/L、反应时间120 min、持续通入空气鼓泡的条件下,乳酸降解效果最佳,乳酸降解率为99.9%;降解12 h总有机碳去除率达91.2%。乳酸光催化降解的反应途径为：乳酸脱羧生成乙醇,乙醇被氧化生成乙醛,进而氧化为乙酸,所有的中间产物被继续降解,最终矿化为CO2和H2O等小分子物质。     

氧化-絮凝耦合处理酸性大红废水的机理研究

用氧化-絮凝耦合法处理酸性大红GR废水,以高锰酸钾为氧化剂、聚硅硫酸铁为絮凝剂,脱色率达到94.9%,COD去除率达到55.2%.通过用倒置式生物显微镜观察絮体,对反应机理进行推测.对高锰酸钾与酸性大红之间氧化还原反应产物和氧化-絮凝耦合处理的絮体进行紫外和红外吸收光谱扫描分析,探讨了氧化-絮凝耦合的反应历程和机理:酸性大红被高锰酸钾氧化成小分子有机物而脱色,还原产物新生态水合二氧化锰胶体吸附小分子有机物,并被聚硅硫酸铁卷裹成紧密絮体,氧化与絮凝之间产生协同作用,从而有效去除了色度和COD.     

TiO2光催化氧化降解乳酸的工艺及机理研究

以TiO2为催化剂、紫外灯为光源对乳酸进行光催化降解实验,考察了乳酸初始浓度、TiO2用量、反应时间、曝气方式等因素对乳酸降解率的影响,并在此基础上应用正交实验对降解条件进行优化,同时对乳酸的降解机理进行了探索研究.实验结果表明:以300 W紫外汞灯为光源,在乳酸初始浓度为O.5 g/L、TiO2量为0.20 g/L、...     

Performance of a field-scale permeable reactive barrier based on organic substrate and zero-valent iron for in situ remediation of acid mine drainage

A permeable reactive barrier (PRB) was installed in Aznalcóllar (Spain) in order to rehabilitate the Agrio aquifer groundwater severely contaminated with acid mine drainage after a serious mining accident. The filling material of the PRB consisted of a mixture of calcite, vegetal compost and, locally, Fe⁰ and sewage sludge. Among the successes of the PRB are the continuous neutralisation of pH and the removal of metals from groundwater within the PRB (removals of >95 %). Among the shortcomings are the improper PRB design due to the complexity of the internal structure of the Agrio alluvial deposits (which resulted in an inefficient capture of the contaminated plume), the poor degradability of the compost used and the short residence time within the PRB (which hindered a complete sulphate reduction), the clogging of a section of the PRB and the heterogeneities of the filling material (which resulted in preferential flows within the PRB). Undoubtedly, it is only through accumulated experience at field-scale systems that the potentials and limits of the PRB technology can be determined.     

Studies on removal of metal ions and sulphate reduction using rice husk and Desulfotomaculum nigrificans with reference to remediation of acid mine drainage

The utility of rice husk as an adsorbent for metal ions such as iron, zinc and copper from acid mine water was assessed. The adsorption isotherms exhibited Langmuirian behavior and were endothermic in nature. The free energy values for adsorption of the chosen metal ions onto rice husk were found to be highly negative attesting to favorable interaction. Over 99% Fe(3+), 98% of Fe(2+) and Zn(2+) and 95% Cu(2+) uptake was achieved from acid mine water, with a concomitant increase in the pH value by two units using rice husk. The remediation studies carried out on acid mine water and simulated acid mine water pretreated with rice husk indicated successful growth of Desulfotomaculum nigrificans (D. nigrificans). The amount of sulphate bioreduction in acid mine water at an initial pH of 5.3 was enhanced by D. nigrificans from 21% to 40% in the presence of rice husk filtrate supplemented with carbon and nitrogen. In simulated acid mine water with fortified husk filtrate, the sulphate reduction was even more extensive, with an enhancement to 73%. Concurrently, almost 90% Fe(2+), 89% Zn(2+) and 75% Cu(2+) bioremoval was attained from simulated acid mine water. Metal adsorption by rice husk was confirmed in desorption experiments in which almost complete removal of metal ions from the rice husk was achieved after two elutions using 1M HCl. The possible mechanisms of metal ion adsorption onto rice husk and sulphate reduction using D. nigrificans are discussed.