臭葱石矿化沉砷研究现状与展望

综述了当前含砷废水臭葱石沉砷工艺的发展现状与研究动态。臭葱石沉砷法因砷渣渣量小、性质稳定等特点被认为是理想的固砷产物。详细阐述了臭葱石沉砷原理、工艺优化与调控、砷渣物相定向调控等,并对该技术的发展趋势进行展望,为有色金属行业清洁高效除砷工艺选择提供参考借鉴。     

稀贵萃余液高结晶臭葱石除砷研究

化学沉淀法处理含砷废水,产物沉砷渣通常不稳定,易导致砷泄露,对环境造成严重的危害。采用沉砷率高、固砷渣稳定的低温常压臭葱石(FeAsO₄·2H₂O)沉砷法进行除砷,并研究了初始pH、Fe/As摩尔比、Fe₂(SO₄)₃滴加速率对As、Fe去除率,FeAsO₄·2H₂O结晶度,形貌和浸出毒性的影响。结果表明：初始pH和Fe/As摩尔比的升高有利于沉砷率的提高,但会导致沉砷渣中FeAsO₄·2H₂O结晶度和含量下降。提高Fe₂(SO₄)₃滴加速率有利于反应效率,但不利于FeAsO₄·2H₂O的纯度。在初始pH为1.5,Fe/As摩尔比为1.5,Fe₂(SO₄)₃滴加速率为40 mL/h以及滴加时间为1.125 h的条件下,...     

水热臭葱石固砷过程Na+和K+的影响

水热臭葱石沉砷体系中Na⁺、K⁺碱金属离子对沉砷渣物相组成影响显著,Fe(Ⅲ)与As(Ⅴ)共沉淀生成臭葱石(FeAsO₄·2H₂O)、次水合砷酸铁(FeAsO₄·0.75H₂O)砷铁共沉淀物,同时Fe(Ⅲ)还以黄钠铁矾(NaFe₃(SO₄)₂(OH)₆)、黄钾铁矾(KFe₃(SO₄)₂(OH)₆)、碱式硫酸铁(Fe(OH)SO₄)形态竞争析出,从而影响沉砷渣的稳定性。在Na₂SO₄-(K₂SO₄)-FeSO₄-H₃AsO₄-H₂O体系中研究了Na⁺、K⁺     

臭葱石法沉砷及井下充填材料制备

针对常规化学沉淀法处理工业含砷废水后得到的含砷固废物稳定性差且无法有效处理的问题,采用臭葱石法处理含砷废水,并进行了以含砷固废物制备井下充填材料的研究。结果表明：在初始pH=2、铁砷摩尔比1.2、反应温度95 ℃、反应时间7 h的最佳条件下,砷的沉淀率为85.07%,所得沉淀物颜色为浅绿色,其中砷含量30.4%、铁含量22.7%,毒性浸出砷浓度为4.33 mg/L。在灰砂比1︰6、料浆浓度65%的最佳条件下,臭葱石的添加量为7%,充填体养护3天后的强度达到1.12 MPa,料浆坍落度约为25.3 cm,满足井下填充要求。充填体毒性浸出砷浓度为1.4 mg/L,满足排放标准。     

臭葱石的合成及其工艺应用研究进展

臭葱石(FeAsO₄·2H₂O)兼具高砷容量和高稳定性,是目前公认最环保安全的固砷材料。臭葱石沉淀法作为一种砷的固定和处置手段,广泛用于含砷废水和含砷固废的处理中。本文首先综述了近几十年发展起来的的3类臭葱石合成方法(水热合成法、常压合成法和生物合成法),并系统地阐述了这些方法的原理、适用范围和优缺点。此外,还论述了一些重要的衍生合成方法,介绍了基于4种合成方法开发的臭葱石工艺的应用。与其他合成方法相比,改进常压法具有操作简单、沉砷效率高、臭葱石颗粒尺寸大和浸出稳定性高等优势,已成为合成臭葱石的主流方法,有可能被广泛采用。     

含砷氰化尾渣的固砷试验研究

将含砷氰化尾渣经过破氰处理后,再进行固砷。考察了硫酸亚铁用量、反应时间及矿浆初始pH对固砷效果的影响。结果表明,较优的固砷条件为:每吨尾渣硫酸亚铁用量110kg、反应时间2h、矿浆初始pH=10。在此条件下,对得到的固砷渣进行了浸出毒性试验,浸出液中总砷含量0.32mg/L,小于2.5mg/L的控制限值,可进入尾矿库处置。     

高砷难处理金矿生物搅拌预氧化工艺研究

研究了矿浆浓度、氧化时间、充气量和氧化过程pH值对某高砷难处理金矿生物搅拌预氧化工艺的影响。结果表明,在矿浆浓度17%、氧化时间7 d、搅拌速度300 rpm、温度40℃、充气量0.4 m3.L-1.h-1、初始pH=2.0、细菌转接量10%,氧化过程不控制pH值时,硫化物氧化率为80.95%,金的浸出率为82.31%。氰化尾渣中硫化物包裹金占其中总金的53.53%,氧化废液中和可使各种有害金属离子达标排放。     

沸腾焙烧预氧化处理含砷金精矿工艺研究

对沸腾焙烧预氧化处理含砷金精矿的工艺过程进行了研究。考察了焙烧气氛、焙烧预处理剂等因素对焙砂表面形貌、金银浸出率及氰化尾渣中金银残留量的影响。结果表明：含砷难处理金精矿在富氧焙烧气氛下所得焙砂表面出现气孔较为均匀的形貌;对氰原（氰化原料,酸浸渣）与氰化尾渣中金银进行化学物相分析发现,硅酸盐包裹是影响金银氰化浸出的主要因素。富氧焙烧气氛下,采用NaOH︰Na2CO3=1︰2复合添加剂所得氰原中硅酸盐包裹金银占比明显下降,焙烧效果大幅改善,金、银浸出率分别提高7.27与13.6个百分点。     

含砷矿石细菌氧化液除砷实验及砷钙渣稳定性研究

以甘肃某金矿经细菌氧化提金后产生的高砷、高铁强酸性细菌氧化液为研究对象,并选择CaO作为沉淀剂进行中和除砷实验,考察pH值、温度、搅拌速度和反应时间等对中和除砷的影响,通过单因素实验确定最佳除砷条件,并探究在模拟自然环境下各因素对砷钙渣稳定性的影响。除砷实验结果表明：在pH=4~5、搅拌速度适宜及常温下反应25 min时,除砷率可达99.99%,实现了废水净化;砷钙渣定量分析结果表明：渣中As、Fe质量分数分别为4.04%和19.79%;模拟自然环境下砷钙渣稳定性影响实验结果表明：当环境pH≤1时,砷钙渣中的砷被溶出了5 mg/L,超过工业废水排放标准。通过试验发现,选择CaO作为沉淀剂对细菌氧化液进行中和除砷,可以实现废水净化,并且当含砷渣所处环境pH≥1时可以稳定存放。     

铜闪速熔炼炉渣中铁橄榄石相固砷机制研究

铜冶炼炉渣含有大量的铁橄榄石相,在闪速熔炼过程中具有较高的固砷潜力。为了厘清铁橄榄石在闪速炉中的固砷条件,以Fe,Fe₂O₃,SiO₂和CaHAsO₄为原料通过高温烧结过程研究铁橄榄石的形成过程,探讨了气氛和温度对铁橄榄石固砷行为的影响。采用X射线荧光光谱(XRF)、扫描电子显微镜(SEM-EDS)、X射线衍射(XRD)、X射线光电子能谱(XPS)和电感耦合等离子体质谱(ICP-MS)等手段对炉渣和烧结试样的成分、物相、形貌和元素化学状态进行表征,同时采用毒性浸出试验(TCLP)和第一性原理分析铁橄榄石固砷的稳定性。结果表明,Ar下烧结产物为铁橄榄石相,且当烧结温度从1000℃升高至1300℃时,铁橄榄石的砷浸出浓度从131.4 mg·L^-1降低到3.563 mg·L^-1,砷浸出率从35.04%降低到0.19%,展现出比氧化烧结后的Fe_3-xSi_xO₄相更高的固砷稳定性。XPS结果表明,空气...     

Modeling As(V) Removal in Iron Oxide Impregnated Activated Carbon Columns

Iron oxide impregnated onto an activated carbon (FeAC) has a high arsenic (As) removal capacity with the potential to be used in existing activated carbon column systems. Objectives of this research were to investigate As(V) removal from aqueous-phase systems using fixed-beds packed with FeAC and to determine if the triple layer model (TLM) with the homogeneous surface diffusion model (HSDM) could describe As(V) removal in the columns. Rapid small-scale column tests (RSSCT) were conducted at various empty bed contact times (EBCT). Effluent As(V) breakthrough (10?μg/L) was incipient for the 0.20-min EBCT experiment, whereas ～ 2300 bed volumes of water at 1-mg/L inlet concentration of As(V) was treated at an EBCT of 2.1?min before breakthrough occurred. The TLM with three As(V)-FeAC surface reactions coupled with the HSDM provided accurate prediction of As(V) removal in the RSSCT.     

As(III), As(V), Hg, and Pb Removal by Fe-Oxide Impregnated Activated Carbon

The removal of As(III), As(V), Hg(II), and Pb(II) by virgin and Fe(III) impregnated activated carbons (FeAC) was investigated. Iron-oxide impregnation increased the pHzpc of the carbon from 7.5 to about 8.2–8.7 but did not alter the surface area or the pore volume. The amount of acid or base needed to reach a given pH increased following impregnation, indicating that the FeAC was more active than its non-impregnated counterpart. Metal removal was a function of pH with removal increasing with pH for Hg(II) and Pb(II) and decreasing with pH for As(V). As(III) removal was not a strong function of pH below pH = 5, increased to a maximum at pH ≈ 7, then decreased with increasing pH. As(III) and As(V) removals were about one and two orders of magnitude higher, respectively, for the FeAC compared with the non-impregnated carbon, while Hg(II) and Pb(II) removals were only slightly higher. Fe-impregnation appears to be most effective for the anionic contaminants.     

As-NaOH-ClO~-体系脱砷试验

提出了在As-NaOH-ClO体系脱砷的方法,并以含砷镍烟灰为原料,系统研究了该体系下的脱砷效果。结果表明:在液固比L/S=10、NaClO浓度4.1%、NaOH浓度3%、反应温度50℃、反应时间1h的最优条件下,砷脱除率达到75%以上,镍损失率小于0.03%,可实现砷的无害化处理和金属镍的回收。     

重金属离子捕集法(DTCR)高效除砷技术研究

针对不同的废水对象,分别开展反应pH值、DTCR捕收剂、混凝剂优选等除砷研究,表明酸性含砷废水采用中和法即可使水中砷含量达国家环保要求,且水体中铁砷比值越大越有利于砷的去除。对碱性含砷废水同时进行扩大试验,砷去除率达99.86%,出水砷含量0.31 mg/L,低于国家环保污水外排要求。该研究结果对环保处理系统短流程及应急性除砷方面具有一定指导意义。     

Adsorption of As(V) from Water Using Nanomagnetite

This paper describes a study of the removal of arsenate [As(V)] from aqueous solutions by adsorption on commercial nanomagnetite (NM). The influences of pH, initial arsenate [As(V)] concentration, and adsorbent concentration were investigated in multiple kinetic runs. The adsorption kinetics and isotherms were investigated in batch experiments. The experimental data were determined to be best described by the pseudosecond-order kinetic model. Langmuir and Freundlich isotherms were used to fit the adsorption data from equilibrium experiments. The findings have revealed that NM has high removal efficiency for arsenate, with its capacity to reduce an initial level of 300 to <5-μg/L As(V), i.e., below the limit (10-μg/L As) set for potable water by the World Health Organization.     

Removal of Nickel(II) from Dilute Aqueous Solution by Sludge-Ash

This work examines the adsorption of Ni(II) onto sludge–ash, a waste produced from a fluidized bed incinerator combusted primarily with biosolids. Results of kinetic experiments showed that the adsorption was rapid. The kinetic adsorption data can be well described by an empirical modified Freundlich equation. The rate of adsorption decreased with either increasing surface loading and ionic strength or decreasing solution pH. The results of equilibrium studies showed that the solution pH was the key factor affecting the adsorption. The modified Langmuir model fit revealed that the hydrogen ion acts as a competitive inhibitor for the adsorption of Ni onto ash. The maximum adsorption capacity for Ni is 5.41 μmol/g. Experimental results indicate that the adsorption is favorable at higher temperature. Thermodynamic adsorption parameters for ΔG°, ΔH°, and ΔS° are ?7.41 kcal/mol, 7.25 kcal/mol, and 48.9 cal/mol?K, respectively.