高硫铝土矿氧化钙焙烧脱硫研究

针对一水硬铝石高硫型铝土矿,以河南矿石为原料,在马弗炉进行焙烧除硫的研究,重点研究了氧化钙在焙烧过程中的作用,并通过对焙烧矿进行X射线衍射来进行理论上的探讨,在此基础上,在熔盐炉中对焙烧矿和原矿进行高压溶出试验,研究溶出液中S2-含量的变化以及焙烧过程对溶出性能的影响。研究结果表明:矿石经焙烧后,硫化物型硫含量降低,加CaO焙烧效果更好;同时CaO起到固硫的作用而降低焙烧过程散于空气中的SO2的含量,原矿在600℃,45min条件下焙烧时,硫化物型硫含量S1%为0.10%,散于空气中的硫含量S3%为0.51%,而加了1%的CaO后,则S1%下降为0.07%,S3%下降为0.31%;焙烧过程中黄铁矿发生反应生成了赤铁矿Fe2O3。原矿经焙烧后进行溶出能显著降低溶出液中S2-的含量,改善矿石的溶出性能。最佳的焙烧温度为600℃,用1%CaO焙烧矿进行溶出,此时相对溶出率为95.35%,二价硫离子含量为0.16 g/L。     

高硫铝土矿微波脱硫机理研究

采用微波焙烧高硫铝土矿脱硫。用X射线衍射仪和常规的化学分析方法分析高硫铝土矿中各种矿物物相组成特征,最主要是得出其中硫的存在形式;运用X射线衍射仪、扫描电子显微镜、高频红外碳硫仪检测仪器,分析微波脱硫后的物相组成。参阅已有的文献资料,以热力学理论分析为基础,利用化学物相分析和物理物相分析,探究了微波焙烧脱硫热力学机理,提出了脱硫机理。     

主要排硫方法简介与评述

铝土矿中通常含有各种硫化物,如黄铁矿、白铁矿等;也有的含硫酸盐,如水绿矾、石膏等。工业铝土矿中硫含量通常达1～2％。用拜耳法生产时,流程中的硫主要来自矿石,例如溶出一水硬铝石时,硫的溶出率为60％左     

高硫铝土矿输送床焙烧脱硫特征

采用输送床粉体物料悬浮态热处理实验装置,对贵州新民地区硫含量1. 29%的高硫铝土矿开展焙烧脱硫试验。考察了稀相悬浮态下焙烧温度和焙烧时间对脱硫效果的影响规律,并探讨了高硫铝土矿焙烧脱硫过程特征。结果表明:在稀相输送床中焙烧温度550℃以上能够在1～2s内实现高硫铝土矿的快速脱硫,550℃焙烧1. 6s,焙烧矿中硫化物型硫含量≤0. 05%,温度对脱硫率的影响权重最大。输送床快速焙烧可有效避免铝土矿中有害硫对后续氧化铝生产过程和产品质量的影响,可以满足氧化铝生产工艺对原料的要求。     

一水硬铝石型铝土矿焙烧碱浸脱硅新工艺(Ⅰ)

针对中、低铝硅比的一水硬铝石—高岭石型铝土矿 ,以山西铝土矿作原料 ,在回转窑上进行了焙烧脱硅工艺研究 ,结果表明 :采用回转窑焙烧铝土矿是可行的 ,其焙烧工艺条件为 :矿石粒度 0～ 2 0mm ,焙烧温度10 5 0～ 110 0℃ ,焙烧时间 15～ 2 0min。在碱浸溶出脱硅条件下焙烧矿的脱硅率达 5 5 .6 1% ,精矿铝硅比为 9.92。X射线衍射分析表明 :焙烧过程中高岭石发生热分解产生的非晶态SiO2 ,在碱浸溶出脱硅过程中溶于NaOH脱除。高压溶出试验表明 :脱硅铝精矿中Al2 O3 的溶出率比原矿要高。     

遵义高硫铝土矿工艺矿物学特征及浮选脱硫试验研究

采用偏光显微镜、X射线衍射仪及QEMSCAN矿物定量分析仪等手段对遵义高硫铝土矿进行了工艺矿物学研究,查清了矿石的物质组成、赋存状态、粒级组成及嵌布特征等工艺性质,确定了一段磨矿一粗一精两扫、扫1底流再磨再选的选矿脱硫工艺流程。工业试验结果表明,在原矿硫含量为1.59%时,取得铝精矿硫含量为0.22%,铝精矿产率为96.16%,硫脱除率为86.70%;硫精矿硫含量为35.86%的较好指标,不仅提供了满足氧化铝生产要求的优质可利用资源,同时实现了含硫矿物的高效利用,变废为宝,对于保护矿山环境,开展高硫铝土矿绿色生产氧化铝技术具有重大的环境和社会效益。     

铝土矿焙烧和溶出脱硅的X射线衍射研究

通过对高岭石和铝土矿焙烧过程物相变化的Ｘ射线衍射研究，阐明了铝土矿化学选矿预脱硅的机理。实验表明，矿石中固有的αＳｉＯ２（石英）是不能被脱除的，只有在焙烧温度高达９００℃以上、由偏高岭石分解形成的那部分非晶ＳｉＯ２才能被ＮａＯＨ溶出而脱除。此外，溶出精矿的相分析结果澄清了过去认为在低压溶出脱硅条件下高岭土是稳定存在的误解。给出了提高铝土矿铝硅比值的最佳焙烧工艺制度。     

低品位高硫铝土矿浮选脱硫工业试验

以河南某低品位高硫铝土矿为研究对象,以实验室浮选脱硫理论的基础上,进行高硫铝土矿浮选脱硫工业试验,使高硫铝土矿达到工业应用。系统考察了磨矿细度、捕收剂用量、浮选浓度及不同浮选流程等浮选条件对高硫铝土矿浮选脱硫指标的影响。试验结果表明:采用一段磨矿,一粗两扫工艺,稳定运转后铝精矿中硫含量由原矿1.87%降至0.31%,低于氧化铝工业所要求的硫含量≤0.5%标准,同时精矿氧化铝回收率达97.13%,硫脱除率达到85.34%,实现了低品位高硫铝土矿的工业应用。     

高硫铝土矿的焙烧预处理及焙烧矿的溶出性能

采用马弗炉、旋转管式炉和流化床对我国高硫铝土矿进行焙烧预处理.考察焙烧温度、焙烧时间对硫含量以及焙烧矿溶出性能的影响;利用SEM和XRD技术对焙烧矿的微观形貌及晶型结构进行表征;探讨高硫矿焙烧脱硫机理.结果表明:焙烧脱硫处理我国高硫铝土矿是可行的,焙烧预处理矿可满足我国氧化铝生产的工业要求;马弗炉、旋转管式炉焙烧预处理的合适工艺条件为:焙烧温度750 ℃,焙烧时间30 min;流化床焙烧预处理的合适工艺条件为:焙烧温度800 ℃,焙烧时间10 min;流态化焙烧矿溶出效果最好,该焙烧矿在溶出温度220 ℃、溶出配料分子比1.3、苛性碱浓度220 g/L的溶出条件下,矿石中氧化铝的相对溶出率可达到93.7%.     

硫从铝土矿向铝酸盐溶液的转移

在拜耳法溶出铝土矿过程中,含硫矿物全部或部分地被分解,致使铝酸盐溶液受到硫的污染。铝土矿中的硫转入溶液的程度与以下许多因素有关:硫化物和硫酸盐的矿物形态,溶出温度和时间,溶出用溶液的碱浓度,铝土矿中的其它杂质(其中包括硫)的含量,等等。文献的作者得出的结论是,铝土矿中的     

Recent studies of cements and concretes by synchrotron radiation crystallographic and cognate methods

The portfolio of available synchrotron radiation techniques is increasing notably for cements and pastes. Furthermore, sometimes the terminology is confusing and an overall picture highlighting similarities and differences of related techniques was lacking. Therefore, the main objective of this work is to review recent advances in synchrotron techniques providing a comprehensive overview. This work is not intended to gather all publications in cement chemistry but to give a unified picture through selected examples. Crystallographic techniques are used for structure determination, quantitative phase analyses and microstructure characterization. These studies are not only carried out in standard conditions but synchrotron techniques are especially suited to non-ambient conditions: high temperatures and pressures, hydration, etc., and combinations. Related crystallographic techniques, like Pair Distribution Function, are being used for the analysis of ill-crystalline phase(s). Furthermore, crystallographic tools are also employed in imaging techniques including scanning diffraction microscopy and tomography and coherent diffraction imaging. Other synchrotron techniques are also reviewed including X-rays absorption spectroscopy for local structure and speciation characterizations; small angle X-ray scattering for microstructure analysis and several imaging techniques for microstructure quantification: full-field soft and hard X-ray nano-tomographies; scanning infrared spectro-microscopy; scanning transmission and fluorescence X-ray tomographies. Finally, a personal outlook is provided.     

石脑油储罐导静电铜丝带腐蚀失效分析

对石脑油储罐导静电铜丝带的腐蚀失效原因进行了分析,通过腐蚀介质分析、X射线衍射定性分析、X荧光光谱定量分析和铜片腐蚀试验,对腐蚀原因和机理进行了验证。证明了铜丝带腐蚀是由石脑油中的H2S和活性硫引起的。并从设备安全运行的角度提出了改进措施。     

Selective adsorption of organic sulfur-containing compounds from diesel fuel using type-Y zeolite and γ-aluminum oxide

Samples based on type-Y zeolite and aluminum oxide (γ-Al₂O₃) with immobilized Cu(I) ions used as adsorbents of molecules of thiophene derivatives during the desulfurization of diesel fuel were investigated. An analysis of diesel fuel after the desulfurization process showed that a decrease in sulfur content caused by contacting adsorbents amounts to 40–80%. Porous structure parameters of the adsorbents before and after contacting diesel fuel were determined using adsorption isotherms of nitrogen vapor at 77K. Desulfurization processes are shown to influence the porous adsorbent structure; therefore, the specific surface and pore size decrease. According to X-ray diffraction, the data on changing the porous adsorbent structure in the desulfurization process are stipulated by the deposition of sulfur and carbon. It was ascertained that the samples based on HY/Cu(I) zeolite better adsorb sulfur-containing compounds than γ-Al₂O₃/Cu(I) do. An analysis of the IR spectra of adsorbent samples after desulfurization indicates the possibility of chemisorbing aromatic components of diesel fuel, most notably sulfur-containing compounds on the surfaces of all investigated samples with the simultaneous transformation of these compounds mainly into aliphatic-type structures.     

The mineralogy of bauxite for producing smelter-grade alumina

Aluminum-producing companies rely on low-cost, high-purity, smelter-grade alumina (aluminum oxide), and alumina production utilizes the bulk of bauxites mined world-wide. The mineralogy of the bauxites has a significant impact on the operation of the Bayer process for alumina production. Typically, the Bayer process produces smelter-grade alumina of 99.5% Al₂O₃, starting from bauxite containing 30% to 60% Al₂O₃. The main objective of the Bayer process is to extract the maximum amount of aluminum from the bauxite at as high an aluminate concentration in solution as possible, while limiting any troublesome side reactions. Only with a better understanding of the chemistry of the mineral species and a strict control of the operating/processing conditions can the Bayer process produce efficiently, a low cost, high-quality alumina with minimum detrimental environmental impact. For more information, contact M. Authier-Martin, Raw Materials R&D, Arvida Research and Development Centre, Alcan International Limited, Jonquiere, Quebec, Canada G7S 4K8; monique.authier@alcan.com.     

MULTI-PEAK MATCH INTENSITY RATIO METHOD OF QUANTITATIVE X-RAY DIFFRACTION PHASE ANALYSIS

A new method for quantitative phase analysis is proposed by using X-ray diffraction multi-peak match intensity ratio. This method can obtain the multi-peak match intensity ratio among each phase in the mixture sample by using all diffraction peak data in the mixture sample X-ray diffraction spectrum and combining the relative intensity distribution data of each phase standard peak in JCPDS card to carry on the least square method regression analysis. It is benefit to improve the precision of quantitative phase analysis that the given single line ratio which is usually adopted is taken the place of the multi-peak match intensity ratio and is used in X-ray diffraction quantitative phase analysis of the mixture sample. By analyzing four-group mixture sample, adopting multi-peak match intensity ratio and X-ray diffraction quantitative phase analysis principle of combining the adiabatic and matrix flushing method, it is tested that the experimental results are identical with theory.     

酸性气氛下钢筋混凝土结构腐蚀行为及其机理

对工业酸性气氛环境下经过10年使用的工厂钢筋混凝土采样,用EDS、XRD和SEM,以及力学性能测试等手段观测了钢筋的腐蚀产物成分和基体成分、混凝土的主要化学组成、微观形貌结构及钢筋的力学性能;另外,还定量分析了钢筋混凝土所处的大气环境中主要腐蚀性气体的含量进行了定量分析.结果表明,含S的酸性气体在箍筋表面的吸附与沉积是钢筋混凝土遭受破坏的主要原因,钢筋腐蚀的发生与C l-诱发的点蚀不同;大量酸性含S及CO2的气体导致混凝土的水泥水化产物和其微观结构发生了变化,特别是含S气体的存在对钢筋混凝土的中性化起重要作用.     

A SOLUTION OF MINIMUM NORM FOR QUANTITATIVE PHASE ANALYSIS BY STANDARDLESS X-RAY DIFFRACTION

A new expression of quantitative phase analysis by standardless X-ray diffraction has beenderived using intensity matrix of vector modulus,The criterion of standardless X-raydiffraction analysis was suggested,so as to separate the diffraction pattern of every phasefrom that of sample.The optimal solution could be obtained by the least squares regression.     

A SOLUTION OF MINIMUM NORM FOR QUANTITATIVE PHASE ANALYSIS BY STANDARDLESS X-RAY DIFFRACTION

A new expression of quantitative phase analysis by standardless X-ray diffraction has beenderived using intensity matrix of vector modulus.The criterion of standardless X-raydiffraction analysis was suggested,so as to separate the diffraction pattern of every phasefrom that of sample.The optimal solution could be obtained by the least squares regression.     

含碳、硼变质的Mg-Al合金的显微组织与力学性能

通过光学显微金相定量分析、SEM扫描电镜及EDX分析、XRD分析以及抗拉强度测试等实验手段,研究了含碳、硼元素复合添加剂的Mg-(6%￣9%)Al合金的显微组织和力学性能的影响。试验结果表明:随着合金中Al含量的增加,在伸长率基本不变的情况下,抗拉强度显著提高。合金的抗拉强度明显增加与铝的固溶强化、第二相强化以及碳、硼的晶粒细化作用有关;而合金的伸长率随着Al的增加而基本不变的主要原因是碳、硼的晶粒细化作用。     

STUDY OF MICROSTRUCTURE ON PAN-ACFS PREPARED BY DIFFERENT ACTIVATION METHODS

1. IntroductionPorous solids play an important role in the fields of separation and purification. Ac-tivated carbon fiber (ACF) is a kind of typically ndcroporous carbonaceous adsorbent,which developed from organic precursors either by physical activation or chemical activa-tion. There are many advant8ges for ACFs comparing with conventional activated carbons(AC), including very faSt adsorption/desorption rates. ACFs can be used in the fOrm ofcloth, paPer or felt and so on. Furthermore A…