Preparation of Micro-Iron Ore Tailings by Wet-Grinding and Its Application in Sulphoaluminate Cement

Herein,micro iron ore tailings(micro-IOTs)were prepared by wet-grinding and applied to improve sulphoaluminate cement(SAC)performance.The physicochemical properties of micro-IOTs were investigated by particle size analysis,XRD,and XPS.The hydrates trait and the hydration mechanism of micro-IOTs-SAC composite were studied by XRD,TGA,MIP,and SEM.The results demonstrated that micro-IOTs with an average grain diameter of 517 nm could be obtained by wet-grinding.The setting time of SAC gradually decreased with increasing micro-IOTs content.By adding 2%micro-IOTs,the compressive strengths of SAC pastes were enhanced about 22%and 10%at 4 h and 28 d,respectively.Moreover,the addition of micro-IOTs accelerated ettringite precipitation and changed its morphology,resulting in early strength improvement of the binary system.And increased later strength by micro-IOTs was closely related to the high content of AH_(3),fine pore structure,and high hydration degree of SAC.The findings suggested one new approach to utilize iron ore tailings in cementbased materials.

Treatment of naphthalene derivatives with iron-carbon micro-electrolysis

The degradation of five naphthalene derivatives in the simulated wastewater was investigated using the iron-carbon micro-electrolysis method.The optimal initial pH of solution and adsorption of iron-carbon and removal efficiency of the total organic carbon(TOC)were investigated.The results show that the removal efficiency of the naphthalene derivatives can reach 48.9%?92.6% and the removal efficiency of TOC is 42.8%?78.0% for the simulated wastewater with 200 mg/L naphthalene derivatives at optimal pH of 2.0?2.5 after 120 min treatment.The degradation of five naphthalene derivatives with the micro-electrolysis shows the apparent first-order kinetics and the order of removal efficiency of the naphthalene derivatives is sodium 2-naphthalenesulfonate,2-naphthol,2,7-dihydroxynaphthalene,1-naphthamine,1-naphthol-8-sulfonic acid in turn.It is illustrated that the substituents of the naphthalene ring can affect the removal efficiency of naphthalene due to their electron-withdrawing or electron-donating ability.

Structural parameter optimization for novel internal-loop iron–carbon micro-electrolysis reactors using computational fluid dynamics

It is generally recognized that internal-loop reactors are well-developed mass and heat-transfer multiphase flow reactors. However, the internal flow field in the internal-loop reactor is influenced by the structure parameter of the reactor, which has a great effect on the reaction efficiency. In this study, the computational fluid dynamics simulation method was used to determine the influence of reactor structure on flow field, and a volume-offluid model was employed to simulate the gas–liquid, two-phase flow of the internal-loop micro-electrolysis reactor. Hydrodynamic factors were optimized when the height-to-diameter ratio was 4:1, diameter ratio was9:1, draft-tube axial height was 90 mm. Three-dimensional simulations for the water distributor were carried out, and the results suggested that the optimal conditions are as follows: the number of water distribution pipes was four, and an inhomogeneous water distribution was used. According to the results of the simulation,the suitable structure can be used to achieve good fluid mechanical properties, such as the good liquid circulation velocity and gas holdup, which provides a good theoretical foundation for the application of the reactor.

Nitrogen removal efficiency of iron-carbon micro-electrolysis system treating high nitrate nitrogen organic pharmaceutical wastewater

The nitrate nitrogen removal efficiency of iron-carbon micro-electrolysis system was discussed in treating pharmaceutical wastewater with high nitrogen and refractory organic concentration. The results show that the granularity of fillings,pH,volume ratios of iron-carbon and gas-water,and HRT. have significant effects on the nitrogen removal efficiency of iron-carbon micro-electrolysis system. The iron-carbon micro-electrolysis system has a good removal efficiency of pharmaceutical wastewater with high nitrogen and refractory organic concentration when the influent TN,NH4+-N,NO3--N and BOD5/CODCr are 823 mg/L,30 mg/L,793 mg/L and 0.1,respectively,at the granularity of iron and carbon 0.425 mm,pH 3,iron-carbon ratio 3,gas-water ratio 5,HRT 1.5 h,and the removal rates of TN,NH4+-N and NO3--N achieve 51.5%,70% and 50.94%,respectively.

Micro-CT评价铁超载影响膝骨关节炎模型小鼠软骨类组织的变化

背景:膝骨关节炎可能与铁代谢异常有关,了解铁超载对膝骨关节炎的作用非常有意义。目的:探究铁超载对膝骨关节炎发病的影响。方法:选取30只7周龄C57B/6J野生型小鼠,采用随机数表法分为正常对照组、手术对照组与手术+右旋糖酐铁组,每组10只。8周龄时,手术+右旋糖酐铁组腹腔注射右旋糖酐铁500 mg/kg,每周1次,注射至18周龄时停止;10周龄时,手术对照组与手术+右旋糖酐铁组行左后膝内侧半月板失稳手术。18周龄时处死所有小鼠,通过Micro-CT检测胫骨微结构参数,番红O-固绿染色观察关节软骨组织病理损伤程度,普鲁士蓝染色证实铁在小鼠关节中的沉积。结果与结论:①Micro-CT检测显示,与正常对照组相比,手术对照组、手术+右旋糖酐铁组骨小梁相对体积、骨小梁厚度、骨小梁数量明显减小(P<0.05),骨小梁分离度、结构模型指数增加(P<0.05);与手术+右旋糖酐铁组比较,手术对照组骨小梁相对体积、骨小梁厚度、骨小梁数量增加(P<0.05),骨小梁分离度、结构模型指数相减小(P<0.05);②番红O染色显示,与正常对照组、手术对照组相比,手术+右旋糖酐铁组小鼠软骨表面缺损、破裂严重,表层软骨细胞数量明显减少,国际骨关节炎研究学会半定量评分更高,提示其关节炎严重程度更高;③普鲁士蓝染色显示,手术+右旋糖酐铁组小鼠滑膜中可见大量被染成深蓝色的铁沉积颗粒,正常对照组与手术对照组均无明显铁沉积颗粒;④结果显示,铁超载能够加重膝骨关节炎的严重程度,并且增加软骨蛋白多糖成分的丢失和软骨下骨的骨丢失,明确了铁超载与膝骨关节炎的关系。

Numerical Simulation of Shrinkage Cavity Formation in Spheroidal Graphite Iron Castings Based on Micro Modeling

A micro-modeling method (MM) for the quantitative prediction of the shrinkage cavity formation in SGiron castings is proposed. The mathematical models describing the volume changes during the solidification ofspheroidal graphite cast iron are established based on the models of solidification kinetics. The shrinkage cavityformation of T-shaped SG iron castings is calculated with MM method. The calculated results are compared with theexperimental results. It is shown that the predicted size, shape and distribution of shrinkage cavity by MM methodare in good agreement with the measured results.

Degradation of Nitrobenzene Wastewater via Iron/Carbon Micro-electrolysis Enhanced by Ultrasound Coupled with Hydrogen Peroxide

The zero valent iron/granular active carbon(ZVI/GAC) micro-electrolysis enhanced by ultrasound(US) coupled with hydrogen peroxide(H_2O_2) was investigated for the deep degradation of nitrobenzene-containing wastewater. The results of scanning electron microscopy-energy dispersive X-rays analysis(SEM-EDS) demonstrated that continuously accelerated regeneration of ZVI and GAC in situ by US could improve the process for converting nitrobenzene(NB) to aniline(AN). H_2O_2 was decomposed catalytically by the byproduct Fe^(2+) ions generated in the micro-electrolysis process to hydroxyl radicals and the organic pollutants in the wastewater were finally mineralized to CO2 and H2O. Effects of the ZVI dosage, the ZVI/GAC mass ratio, the initial pH value and the H_2O_2 dosage on the efficiency for degradation of NB were studied in these experiments. The optimal operating conditions covered a ZVI dosage of 15 g/L, a ZVI/GAC mass ratio of 1:2,an initial pH value of 3 and a H_2O_2 dosage of 4 mL. In this case, the NB removal efficiency reached 97.72% and the total organic carbon(TOC) removal efficiency reached 73.42% at a NB concentration of 300 mg/L. The reduction of NB by USZVI/GAC followed the pseudo-first-order kinetics model, and the pseudo-first-order rate constants were given at different initial pH values. The reaction intermediates such as AN, benzoquinonimine, p-benzoquinone, p-nitrophenol and other organic acids were detected and a probable pathway for NB degradation has been proposed.

融合石膏组分和微纳米结构“双基因”调控的铁尾矿粉无熟料固结体力学性能

为了探究超细铁尾矿粉颗粒表面非晶态SiO_(2)和Al_(2)O_(3)在石灰-石膏体系中的水化固化机理及调控因素,本工作考察了石膏掺量和铁尾矿粉中微纳米级颗粒含量之间的匹配对固结体强度的影响,利用XRD、TG-DSC、SEM和化学滴定法测试分析了固结体试样中水化产物的种类、形貌及含量的变化,研究了这些变化对固结体强度的影响及作用机理。结果表明,超细铁尾矿粉中小于1.096μm的微纳米颗粒含量显著影响着铁尾矿粉在碱溶液中Si和Al元素的溶出行为,固结体强度随着这些微纳米颗粒含量的增加而提高。固结体中的主要水化产物是铝掺杂的水化硅酸钙(C-(A)-S-H)和钙矾石(AFt)。石膏掺量与铁尾矿粉中微纳米颗粒含量的最佳匹配值对固结体的强度具有显著影响,并且微纳米颗粒含量越高,对应的石膏最佳掺量越大。石膏组分保证了AFt的生成和稳定,同时也加速了铁尾矿粉颗粒表面非晶态成分的水化。本工作探明了固结材料中最佳石膏掺量与微纳米铁尾矿粉颗粒含量的关联关系及其机理,证实了微纳米级颗粒是无熟料固结体结构中的基本活性单元,石膏的掺入对微纳米颗粒的水化起到调控作用,水化后的微纳米颗粒演变为固结体的基本结构单元,这种组分和结构的“双基因”调控机制影响着固结体的力学性能。

规整化铁碳材料的制备及降解高浓度苯酚的研究

以高浓度苯酚为研究对象,以还原铁粉、活性炭和膨润土为原料,通过高温微孔活化技术制备了一种规整化铁碳填料(Fe/C-BM)。采用SEM、XRD对其反应前后的表观形貌和晶体结构进行了表征,并考察了填料投加量,苯酚初始浓度,初始pH和曝气量对苯酚去除效果的影响,结果显示微电解反应前的Fe/C-BM填料表面凹凸不平,具有一定的孔隙结构。Fe/C-BM填料中铁以Fe^(0)和Fe_(2)O_(3)两种形式存在;反应后填料表面呈花纹状,其产物为Fe^(0)氧化后生成新的Fe_(2)O_(3)。曝气条件对微电解效果影响显著,酸性和中性溶液中去除效果优于碱性。当铁碳投加量在30 g/L,苯酚初始质量浓度为250 mg/L,初始pH=6.5,曝气量为2.4 L/min时,微电解120 min去除了83.6%的苯酚。

Fenton耦合铁碳微电解技术处理电镀废水的工艺优化

以福建某电镀厂镀镍废水为研究对象,采用Fenton耦合铁碳微电解技术对其进行处理,考察了铁投加量、铁碳质量比、初始pH值及H_(2)O_(2)投加量对COD_(Cr)去除率的影响,通过响应面法优化工艺条件,建立二次多项式预测模型,分析各因素间的交互作用,并检验模型的准确性。结果表明,各因素对COD_(Cr)去除率的影响显著性排序为:初始pH值>H_(2)O_(2)投加量>铁碳质量比>铁投加量;当铁投加量为40 g·L^(-1)、铁碳质量比为0.8、初始pH值为4.0、H_(2)O_(2)投加量为30 mmol·L^(-1)时,COD_(Cr)去除率为78.2%,与预测值(78.9%)基本吻合,说明采用响应面法优化得到的工艺条件准确可靠。

曝气位置对铁碳-沸石人工湿地污染物去除和温室气体排放的影响及微生物群落分析

为探究曝气位置与铁碳-沸石填充体积比对人工湿地污水净化及温室气体排放的影响,根据曝气位置和铁碳-沸石填料体积比不同构建了8个人工湿地,其中全程曝气处理分别为:F8T2(80%沸石+20%铁碳)、F6T4(60%沸石+40%铁碳)、F4T6(40%沸石+60%铁碳)、以及对照组F(100%沸石);半程曝气人工湿地分别对应为:F8T2-P、F6T4-P、F4T6-P和F-P。对人工湿地系统出水水质、温室气体和微生物群落进行分析测定。结果表明,与全程曝气相比,半程曝气显著提升了各人工湿地上层水中DO的含量(P<0.05),COD和NO_(3)^(-)-去除率均达到94.5%以上,F8T2-P、F6T4-P和F4T6-P出水中NH_(4)^(+)-N平均质量浓度分别显著降低了50.40%、54.18%和51.00%(P<0.05)。曝气位置对铁碳-沸石人工湿地CH_(4)排放影响并不显著,但显著减少了N_2O的排放(P<0.05)。相较于全程曝气人工湿地,F8T2-P、F6T4-P和F4T6-P中N_(2)O排放通量分别显著降低了44.03%、35.62%和44.54%(P<0.05)。添加铁碳增加了pmo A、nos Z、nir S和nir K基因丰度,降低了mcr A基因丰度,这些基因与反硝化过程和温室气体排放有关;同时,F8T2-P、F6T4-P和F4T6-P中优势菌属Micropruina、Propionicicella、Nitrospria、Thauera、Denitratisoma、Dechloromonas有利于硝化和反硝化反应的进行。半程曝气且铁碳与沸石体积比为2:8的人工湿地,具备最佳的污染物去除和温室气体减排潜能。

高镍奥氏体球墨铸铁涡壳的铸造工艺优化

介绍了高镍奥氏体球墨铸铁涡壳铸件的结构及铸造工艺,针对试制过程中出现的表面缩孔、缩松、显微缩松以及组织中的碎块状石墨、表面恶化层、碳化物等问题进行了工艺优化,最后指出:(1)高镍奥氏体球墨铸铁液态收缩量大、石墨化膨胀弱,冒口设计遵循顺序凝固原则是防止涡壳产生缩孔、缩松缺陷的有效措施;(2)涡壳厚处和舌尖易形成碎块状石墨,强化孕育可防止缺陷的产生;(3)表面恶化层超标,可通过较高的残余镁量和砂芯刷涂料进行防止;(4)由于冷却速度较慢,舌尖部位碳化物析出数量较多,良好的孕育可减少碳化物析出量,热处理也可改变碳化物体积分数及其形态。

铁碳微电解-Fenton氧化法处理石化工业有机废水

为探讨用铁碳微电解-芬顿氧化工艺处理石化工业的有机废水的最适处理效果。通过单因素实验与正交实验分别研究铁碳微电解法和Fenton氧化法的最适反应条件,基于此进行平行实验,根据实验结果分析选择采用铁碳微电解-Fenton氧化一体式联用工艺,再通过正交实验得出最佳反应条件:初始pH为2.5、铁碳投加量140 g/L、铁碳反应时间1 h、Fe^(2+)/H_(2)O_(2)投加比为1∶2.72,芬顿反应时间2 h,出水COD_(Cr)为307~327 mg/L,COD_(Cr)去除率为51%以上。影响联用工艺反应处理效果的大小顺序为:初始pH>铁碳反应时间>铁碳投加量>Fe^(2+)/H_(2)O_(2)投加比>反应时间。联用工艺相较单一实验处理废水,处理后COD_(Cr)浓度均未可达到水污染物排放标准限值中石油化工工业第二时段二级标准,处理效果仅于物理现象上有所提升,但COD_(Cr)去除率并无明显提升,处理效果不够彻底,适宜作为有机废水的预处理方法。

激光烧蚀方式对织构化球墨铸铁摩擦磨损性能的影响

[目的]为提高球墨铸铁表面的耐磨性,分析了不同激光烧蚀方式对织构化球墨铸铁摩擦磨损性能的影响。[方法]采用传统激光逐点烧蚀方法在球墨铸铁表面直接制备规则的微织构阵列,以及采用激光连续扫描的方式在球墨铸铁表面原位诱导制备不规则的微织构阵列,两种微织构阵列的平均直径和平均面密度保持相同,随后在油润滑条件下进行摩擦磨损试验。通过表面硬度、表面成分、摩擦因数、磨损率等检测,探讨了两种织构化球墨铸铁表面的减摩抗磨性能及机理。[结果]激光逐点烧蚀方式未能提升球墨铸铁的表面硬度,摩擦因数和磨损率分别比原始样件减小9.3%和75%,摩擦磨损试验后表面发生了明显氧化。激光连续扫描方式将球墨铸铁表面硬度由(273±25)HV提升至(428±36)HV,摩擦因数和磨损率分别比原始样件减小20%和78%,摩擦磨损试验后表面未发生明显氧化。[结论]相比逐点烧蚀微织构试样,激光连续扫描制备的微织构样品表面的减摩抗磨性能更优异,同时减少了摩擦时产生犁沟、塑性变形、磨损碎屑等现象,其摩擦学性能的提高归因于非织构区域表面硬度的提高,以及微织构对磨粒的捕捉、储油及动压润滑效应的协同作用。

酸化-微电解-Fenton组合工艺处理PCB显影废水中有机物的研究

印制电路板(PCB)行业产生的显影废水是一种成分复杂、难以生化降解的高浓度有机废水。本文首先采用单因素实验确定酸化、铁碳微电解、Fenton氧化反应的最佳反应条件,其中酸化pH值为2;铁碳微电解条件:铁碳质量比取2,百毫升废水药剂投加量为3 g,pH值为2,反应时间为30 min;Fenton氧化条件:初始pH值为3,H_(2)O_(2)与Fe^(2+)的摩尔比为6,百毫升废水需加入H_(2)O_(2)0.6 m L,反应时间为90 min。其次,通过酸化-铁碳微电解-Fenton氧化组合工艺处理该废水,经组合工艺处理后,废水中的COD_(Cr)浓度从原来的5 320 mg/L降至432 mg/L左右,去除率达91%左右,为工厂废水预处理提供了依据。

铁碳微电解法处理垃圾渗滤液的研究

针对当前垃圾渗滤液普遍存在的有污染物浓度高、有机污染物含量多且难降解问题,采用铁碳微电解法对该废水进行处理,以垃圾渗滤液中COD的去除率为指标,考察初始pH值、反应时间和铁碳投加量3个主要因素对废水中有机污染物去除效果的影响。结果表明:3个因素对实验结果的影响程度比较为:初始pH值>反应时间>铁碳投加量。当初始pH=3,反应时间120 min,铁碳投加量66 g/L时,垃圾渗滤液中COD的去除率可以达到53.5%。因此,铁碳微电解法处理垃圾渗滤液具有良好的效果,可以为该工艺在垃圾渗滤液治理领域中的应用提供一定的参考。

氯化钠对铁碳微电解工艺处理硝基苯废水的影响研究

为了探究铁碳微电解工艺在含盐环境下对水中污染物的去除效率和稳定性,以硝基苯作为处理对象,以氯化钠为盐分来源,构建模拟废水的连续处理装置,通过单因素试验获得反应最佳条件。研究结果表明,铁碳微电解处理硝基苯废水的最佳条件为:废水初始pH值为3,水力停留时间为2 h,曝气量为1 L/min;此条件下氯化钠对铁碳微电解降解硝基苯具有明显的强化作用,在氯化钠质量分数为0.5%~1.5%时,硝基苯去除率可提高20%~30%。

铁-碳微电解法处理铜冶炼含砷废水的实验研究

采用铁-碳微电解法处理铜冶炼含砷废水,考察了进水pH值、空气鼓入量、接触时间、振动频率、固液比(铁-碳微电解材料质量∶每分钟进水质量)等工艺参数对除砷效率的影响。结果表明,铁-碳微电解材料处理铜冶炼含砷废水时,生成的FeAsO4、Fe2O3、Fe3O4等氧化物沉积在铁-碳微电解材料表面,使铁-碳微电解材料钝化失效,导致除砷效率差,采用振动的方法可有效解决铁-碳微电解材料钝化失效问题;在进水pH值2.0、空气鼓入量5 L/min、接触时间2 min、固液比2.5∶1、振动频率每4 h振动2 min条件下,铁-碳微电解材料连续稳定处理废水90 d,除砷率达99.99%,水中砷含量降至0.033~0.036 mg/L,除砷效果理想且稳定。采用铁-碳微电解法除砷,为处理铜冶炼含砷废水提供了新思路。

不同粒径零价铁对微氧脱氮系统的影响

构建了部分硝化反硝化厌氧氨氧化(SNAD)微氧体系,并定期向体系内投加120 mg不同粒径的零价铁(ZVI),从反应器运行情况、微生物性能以及群落结构来探究不同粒径ZVI对微氧系统的影响。研究结果表明,在50 nm粒径ZVI(50 nZVI)的介导下,系统的TIN去除率最终稳定在83.591%,电子传递活性(ETSA)是接种污泥的1.48倍,均高于其他粒径ZVI的影响。越小粒径ZVI越能促进胞外聚合物的产生,有利于活性污泥结构稳定。这都源于粒径越小的ZVI更容易被微生物吸附、利用。微生物群落结构与功能分析结果表明,在粒径越小的ZVI介导下的微生物群落多样性越高,群落结构也越复杂。ZVI介导会促进对氧需求不敏感的微生物的富集,样品中主要检测出Candidatus_Brocadia和Candidatus_Kuenenia两种厌氧氨氧化菌(AnAOB),且在50 nZVI影响下丰度最高,分别为4.650%和0.692%。nZVI介导下,AnAOB与Gemmobacter和norank_f_Comamonadaceae两种兼性厌氧型反硝化菌共同作用构成SNAD的脱氮途径。而在mZVI介导下,兼性厌氧型反硝化为主要脱氮途径。

Micro-arc oxidization fabrication and ethanol sensing performance of Fe-doped TiO_2 thin films

In-situ pure TiO2 and Fe-doped TiO2 thin films were synthesized on Ti plates via the micro-arc oxidation （MAO） technique. The as-fabricated anatase TiO2 thin film-based conductometric sensors were employed to measure the gas sensitivity to ethanol. The results showed that Fe ions could be easily introduced into the MAO-TiO2 thin films by adding precursor K4（FeCN）6＇3H20 into the NaaPO4 electrolyte. The amount of doped Fe ions increased almost linearly with the concentration of Kg（FeCN）63H20 increasing, eventually affecting the ethanol sensing performances of TiO2 thin films. It was found that the enhanced sensor signals obtained had an optimal concentration of Fe dopant （1.28at%）, by which the maximal gas sensor signal to 1000 ppm ethanol was estimated to be 7.91 at 275℃. The response time was generally reduced by doped Fe ions, which could be ascribed to the increase of oxygen vacancies caused by Fe3＋ substituting for Ti4＋.