热处理条件对含钛高炉渣中钙钛矿相析出行为的影响

为了实现攀钢含钛高炉渣中钛组分的有效回收,研究了将钙钛矿作为钛的富集相时,不同热处理条件对钙钛矿相选择性析出行为的影响。通过分析化学组分及矿物组成特点,结合相图理论,采用选择性析出技术,探索了Fe_2O_3加入量、结晶温度、结晶时间及降温速度对钙钛矿富集效果的影响。试验结果表明,原渣加入2.54%CaO为调整剂,经1 025℃预氧化30 min后,再与1%的Fe_2O_3混匀,在1 470℃下熔融60 min,然后以0.5℃/min降温速率降至1 320℃并恒温90 min,最终所获得的改性渣中钙钛矿结晶量为30.62%、晶粒大小为63.17μm,实现了含钛高炉渣中TiO_2的有效富集,为钙钛矿与钛辉石的浮选分离创造了条件。     

含钛炉渣碳热还原热力学计算

对含钛炉渣碳热还原过程进行了详细的热力学计算分析,结果如下:含钛炉渣碳热还原过程中Ti O_2被还原成一系列钛的低价氧化物,TiO_2转变为Ti_3O_5的开始温度为1 359 K,之后可能形成Ti_2O_3和TiC_xO_y,最终形成TiC;含钛炉渣中CaO、MgO和Al_2O_3不与C发生反应;Fe_2O_3、V_2O_5、Mn O和SiO_2可以被C还原,且还原难度依次增加;早期形成的TiC可能与TiO_2发生反应,形成Ti_3O_5等低价化合物;含钛炉渣中CaTiO_3不直接与C发生反应,CaTiO_3熔融后被C还原为TiC。热力学计算为分析含钛炉渣中各种矿物在碳热还原过程中的转变过程提供了重要依据。     

攀枝花钛渣NaOH分解-HCl浸出制备TiO2的工艺研究

以攀枝花钛渣为原料,采用NaOH分解-HCl浸出的方法制备TiO_2。通过XRD射线衍射手段分析钛渣被NaOH分解过程中的物相变化。结果表明:NaOH分解钛渣是分步进行的,即M_3O_5(M=Fe~(2+),Ti~(3+),Ti~(4+))→Fe_3Ti_3O_(10)→Fe_2TiO_5→α-NaFeO_2,Na_2TiO_3。在HCl浸出制备TiO_2的试验中,分析盐酸浓度、加铁量、溶液pH值、沉积温度和沉积时间等因素对最终样品TiO_2含量的影响。通过优化试验,确定最优工艺条件为:沉积温度45℃、沉积时间40 min、盐酸浓度5 mol/L、加铁粉量0.6 g、溶液pH=2。按照最佳条件进行验证试验,所制备样品TiO_2含量达98.36%。     

赤泥酸浸提钛实验研究

分采用硫酸、盐酸和硝酸三种浸出剂从赤泥中提取钛,考察了浸出剂种类和浓度、液固比、浸出温度及反应时间等因素对钛浸出率的影响。结果表明,硫酸作为浸出剂最为合适,在硫酸浓度40%、浸出温度100℃、液固比6∶1和反应时间60min条件下,钛浸出率可达90%。浸出过程物相变化包括赤泥中板钛矿和方解石的消失,钙钛矿、赤铁矿和钙霞石的减少以及硬石膏的出现。板钛矿和钙钛矿与硫酸发生溶解反应,使得赤泥中钛得以浸出。     

攀枝花低硅钛精矿还原试验研究

以攀枝花低硅钛精矿为研究对象,研究氧化温度和时间对钛铁矿物相结构和还原的影响,同时对预氧化钛铁矿不同温度和时间下还原失重率和金属化率变化情况进行分析。研究结果表明:钛精矿的氧化在较短时间内可完成,随着氧化温度的升高,钛精矿主要物相变化过程为FeTiO_3→Fe_2O_3+TiO_2→Fe_2TiO_5+Fe_2O_3+TiO_2;在钛铁矿的还原过程中,还原温度和时间对钛铁矿还原的金属化率影响较大,在还原温度大于1 300℃,时间大于8 h后变化不明显;显微结构分析发现,高温还原后金属铁扩散发生聚集,形成球形和棒状金属铁颗粒,其尺寸大约为10μm。     

CaH_2低温热还原TiO_2制备钛粉

以工业钛白粉和分析纯氢化钙粉为原料,探索一种在较低温度下热还原制备Ti粉新方法。结合反应热力学理论计算及试验验证,对氢化钙分解条件及分解产物还原TiO2过程进行了研究。结果表明:真空条件可降低CaH_2分解温度,初始真空度2.5 Pa,温度890.7 K,保温1 h,CaH_2分解为Ca和H_2;分解后的Ca粉对TiO_2的还原为逐级还原,在温度993 K以上、还原时间3 h,Ti_nO_(2n-1)及CaTiO_3等中间产物最终被还原为Ti;反应结束时通过蒸馏去除残余Ca可有效降低Ti粉H含量;获得的钛粉颗粒形貌为不规则块体状、中位粒径1.83μm,成分满足行业标准YS/T 654-2007 TF-2牌号要求。     

攀枝花钛精矿还原锈蚀法研究

攀枝花钛精矿经过1 000℃氧化1 h后通过H_2/CO混合气体1 000℃还原1 h得到还原钛精矿,研究还原钛精矿在NH_4Cl溶液体系下钛铁分离效果以及锈蚀产物中铁副产品的存在形式。结果表明:金属化率为92.40%的钛精矿在合适的锈蚀体系下能够将锈蚀产物中富钛料的品位提高到75.12%;锈蚀溶液中添加盐酸能够继续提高富钛料中TiO_2的品位至81.76%;锈蚀副产物铁副产品中能够得到较为纯净的Fe_3O_4,γ-FeO(OH)相或者得到由γ-FeO(OH)、α-FeO(OH)以及Fe_2O_3构成的混合物。     

钛酸钙化合物合成热力学与溶出动力学行为

对不同钛酸钙化合物Ca Ti O3、Ca4Ti3O10和Ca3Ti2O7的生成热力学和酸溶动力学进行了研究,结果表明,烧结温度在473~2 000 K时,Ca4Ti3O10、Ca3Ti2O7和Ca Ti O3均能生成;溶出温度在273~573 K时,Ca4Ti3O10、Ca3Ti2O7、Ca Ti O3的酸溶性逐渐减弱.溶出温度在338~358 K范围内,溶出过程受化学反应控制;溶出温度在403~443 K范围内,溶出过程受固膜扩散控制..     

熔渣吸收TiO2夹杂物的研究

采用旋转动力学实验方法,模拟研究了含钛不绣钢连铸时熔融保护渣吸收TiO_2夹杂物的过程,探讨了CaO-SiO_2-CaF_2-BaO系渣中,CaF_2,BaO,TiO_2,Na_2B_4O_7,碱度(CaO/SiO_2)等因素对熔渣吸收TiO_2的速度以及CaTiO_3析出倾向的影响。     

褐铁型红土镍矿硫酸熟化过程及其机制研究

以褐铁型红土镍矿为原料,研究了其硫酸熟化过程及其矿物物相转变机制。考察了熟化过程中温度、时间、硫酸量、加水量对熟化过程的影响,结果表明:Ni,Co浸出率随熟化温度的升高、硫酸用量的增加、熟化时间的延长而提高,一定的加水量有利于Ni,Co的浸出。熟化最佳工艺条件为:温度450℃、硫酸量为每吨矿500 kg、时间60 min、加水量20%,在该条件下,Ni,Co和Fe的浸出率分别为78.1%,91.1%和9.6%。采用热重-差示扫描量热法(TG-DSC)、X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)对硫酸熟化过程矿物物相转变机制进行了研究,结果表明:200℃下熟化,矿相未被破坏,以针铁矿(FeOOH)为主;250℃时,部分FeOOH转变为赤铁矿(Fe_2O_3)和不溶性的碱式硫酸铁(Fe(OH)SO_4);300~350℃时,矿物结构被有效破坏,绝大部分FeOOH转变为Fe_2O_3;升温到400℃,Fe(OH)SO_4分解为Fe_2O_3;450℃时,完全可见Fe_2O_3且其结晶度最好;500℃时,Fe(OH)SO_4转变为硫酸铁(Fe_2(SO_4)_3),但仍以Fe_2O_3为主。大部分Ni,Co矿物转化为可溶性硫酸盐,少量转变为不溶性的铁酸镍(NiFe_2O_4)、铁酸钴(CoFe_2O_4),造成Ni,Co的损失。     

高碱高钙介质黄铁矿抑制及铵盐活化机理的现状与展望

文章主要介绍了黄铁矿在高碱高钙介质中被抑制的机理及铵盐对其活化机理,CaO、Ca(0H)+、CaS04、Ca(OH)2、Fe( OH)2 、Fe( OH)3、Fe2(SO4)3、Fe2 (SO4)3 ·9H2O、FeSO4、FeS04·7H2O等亲水性物质罩盖在黄铁矿表面使其表面亲水;而铵盐活化黄铁矿的机理体现在适当降...     

Effect of different dopants on the long lasting phosphorescence behavior of CaTiO_3：Pr~（3＋）

In order to improve the luminescence properties of CaTiO3:Pr3+, a series of CaTiO3:Pr3+, such as CaTi0.97Nb0.03O3:Pr3+, Ca0.8Zn0.2TiO3: Pr3+, Ca0.8Zn0.2Ti0.97Nb0.03O3:Pr3+ and B3+-doped Ca0.8Zn0.2Ti0.97Nb0.03O3: Pr3+ were prepared through conventional solid state reaction method. The results of the photoluminescence excitation and emission spectra showed that all the samples emitted red phosphorescence at 612 nm originating from 1D2 to 3H4 emission of Pr3+ under the 337 nm excitation. When examined by the X-ray diffraction (XRD), all the samples presented a predominant phase of CaTiO3 (JCPDS# 42-423) except Zn2+-doped samples which also revealed another phase of Zn2Ti3O8 (JCPDS# 73-579). The results of the afterglow decay curves showed that co-doping Zn2+ ions, Nb5+ ions or adding a small amount of B3+ into Ca0.8Zn0.2Ti0.97Nb0.03O3:Pr3+ were effective in improving the photoluminescence properties of CaTiO3:Pr3+ phosphor. Thermoluminescence results showed that the trap existing in all the samples was the same as in CaTiO3:Pr3+ and doping singly Nb5+ or Zn2+ hardly changed the trap depth but co-doping Nb5+ and Zn2+ could modify the trapping level from 0.63 to 1.26 eV distinctively. In addition, adding a certain amount of B3+ into CTO-PZN could also deepen the trap depth.     

高温还原性气氛下TiOx-SiO2-MgO系结晶过程的研究

实验通过定组成的H2/CO2混合气控制氧分压,在温度为1873 K、1673 K、1473 K,氧分压为1.22×10-8~2.18×10-12 Pa、4.92×10-8~8.79×10-12 Pa的范围内,研究了TiOx-SiO2-MgO 系的析出相.结合XRD和EDS分析并对比汪大亚等人的研究可知,当氧分压较高（PCO∶PCO2=5∶1）时,对于初始成分TiO2∶MgO∶SiO2摩尔比为60∶25∶15的试样,在1873 K 和1673 K 时的析出相为TiO2,在1473 K 时其析出相为MgTi2O5;对于初始成分TiO2∶MgO∶SiO2摩尔比为60∶15∶25的试样,在1873 K时其析出相为TiO2,在1673 K和1473 K时析出相为MgTi2O5.而当氧分压较低（PH2∶PCO2=600∶1、300∶1、150∶1）时,2种不同成分的试样在不同温度下的析出相均为黑钛石,并且随着氧分压的降低,黑钛石中的Mg 含量逐渐减少.     

添加剂对烧成镁钙砖烧结性能的影响

研究了TiO2,Fe2O3及CeO2作为添加剂对烧成镁钙砖烧结性的影响，发现它们在一定程度上促进了镁钙砖的烧结，其中以TiO2作为添加剂的效果最好，添加TiO2,Fe2O3与CaO反应生成了CaTiO3和Ca2Fe2O5，添加CeO2与CaO不生成化合物。三种添加剂促进镁钙砖烧结的机理各不相同。     

Effects of embedding direct reduction followed by magnetic separation on recovering titanium and iron of beach titanomagnetite concentrate

Embedding direct reduction followed by magnetic separation was conducted to fully recover iron and titanium separately from beach titanomagnetite(TTM).The influences of reduction conditions,such as molar ratio of C to Fe,reduction time,and reduction temperature,were studied.The results showed that the TTM concentrate was reduced to iron and iron-titanium oxides,depending on the reduction time,and the reduction sequence at 1 200°C was suggested as follows:Fe_(2.75)Ti_(0.25)O_4→Fe_2TiO_4→FeTiO_3→FeTi_2O_5.The reduction temperature played a considerable role in the reduction of TTM concentrates.Increasing temperature from 1 100 to 1 200°C was beneficial to recovering titanium and iron,whereas the results deteriorated as temperature increased further.The results of X-ray diffraction and scanning electron microscopy analyses showed that low temperature(≤1 100°C)was unfavorable for the gasification of reductant,resulting in insufficient reducing atmosphere in the reduction process.The molten phase was formed at high temperatures of 1 250-1 300°C,which accelerated the migration rate of metallic particles and suppressed the diffusion of reduction gas,resulting in poor reduction.The optimum conditions for reducing TTM concentrate are as follows:molar ratio of C to Fe of 1.68,reduction time of 150 min,and reduction temperature of 1 200°C.Under these conditions,direct reduction iron powder,assaying 90.28 mass%TFe and 1.73 mass% TiO_2 with iron recovery of 90.85%,and titanium concentrate,assaying 46.24mass% TiO_2 with TiO_2 recovery of 91.15%,were obtained.     

碱中毒对烧结烟气SCR催化剂脱硝脱二噁英的影响

摘要：采用湿式浸渍法对商用V2O5-WO3/TiO2催化剂进行了碱金属硫酸盐（Na/K/Rb）中毒实验。在模拟铁矿烧结烟气条件下，对比了新鲜和中毒催化剂同时脱除NOx和二噁英的活性（以氯苯作为二噁英的模拟物），并通过N2吸脱附、XRD、NH3 TPD、H2 TPR和XPS等检测手段对催化剂进行了表征。结果表明：中毒催化剂的脱除NOx和催化降解氯苯活性明显降低，失活率顺序为K2SO4>Rb2SO4>Na2SO4。催化剂中毒后，碱金属离子可以占据催化剂表面化学吸附氧空位，导致表面化学吸附氧数量减少，物质的量之比n(V5+)/n(V4+)降低，V物种可还原性减弱。     

硫酸法钛白副产绿矾的利用途径及其净化提纯方法

根据文献资料,本文总结介绍了硫酸法钛白生产过程中副产绿矾（FeSO2·7H2O）的利用途径及其净化提纯方法。     

铬掺杂黄钾铁矾微球的制备及OER性能研究

采用水热合成法制备出不同微观形貌的铬掺杂黄钾铁矾纳米球(KFe3-xCrx(SO4)2(OH)6)。利用XRD、SEM、FTIR和Raman对催化剂的微观结构及物理化学性质进行了表征,使用电化学工作站对样品进行电催化析氧性能(OER)测试。结果表明,Cr3+取代部分Fe3+的位置,随着摩尔比n(Fe3+/Cr3+)的提高,黄钾铁钒由不规则的纳米颗粒转变成尺寸均一的纳米球。当n(Fe3+/Cr3+)=2时,合成的KFe2Cr1(SO4)2(OH)6表面光滑、直径约为450~550 nm。当电流密度为10 mA/cm2时,过电位为362 mV,塔菲尔斜率为73 mV dec-1;恒电位测试20 h后电压无明显变化,基本趋于稳定。说明KFe2Cr1(SO4)2(OH)6微球表现出良好的OER催化活性和稳定性,为黄钾铁矾的应用提供了新的方向。     

干湿交替环境下气体组成对低合金钢腐蚀行为的影响

参照国际海事组织(IMO)所规定的模拟货油舱上甲板(COT)试验条件,利用专门建立的模拟上甲板环境腐蚀试验装置,研究了货油舱上甲板环境中,不同气体成分对低合金钢的腐蚀行为的影响.观察了低合金钢在不同成分的气体中基体和腐蚀产物的宏观和微观形貌,测定了锈层的物相组成.研究结果显示,在干湿交替环境下,低合金钢在SO2+ CO2+O2+N2气体中的腐蚀速率是H2S+ N2气体中的5.7倍;H2S+ N2环境下腐蚀产物为FeS,SO2+CO2+ O2+ N2环境下腐蚀产物为α-FeOOH、Fe2O3、FeSO4,且基体表面存在沿晶界发生的沟渠状和酸性液滴造成的斑状腐蚀形貌.     

Patients with multidrug-resistant tuberculosis with low CD4+ T cell counts have impaired Th1 responses

Canine lingual arteries are innervated by calcitonin gene-related peptide (CGRP)-containing vasodilator nerves. Although the vascular system might be considered as the first target of oxygen-derived free radicals in some of the pathophysiological conditions, the effect of oxygen-derived free radicals on neurotransmission in CGRP nerves remains unknown. We, therefore, investigated the role of oxygen-derived free radicals generated from Fenton's reagent (3 x 10(-4) M H2O2 plus 2 x 10(-4) M FeSO4) on CGRP-mediated neurogenic relaxation of canine lingual artery ring preparations. In all experiments, endothelium-denuded preparations (which were suspended in the tissue bath for isometric tension recordings) were treated with guanethidine (5 x 10(-6) M) to block neurogenic constrictor responses. The periarterial nerve stimulation (10 V, 4-16 Hz, for 45 sec), exogenous CGRP (10(-8) M) or the ATP-sensitive K+ channel opener cromakalim (10(-6) M) produced relaxation of the rings at a stable plateau tension by the addition of norepinephrine (10(-5) M); the relaxations elicited by CGRP and cromakalim were human CGRP-(8-37)- and glibenclamide-abolishable, respectively. When the nerve stimulation, CGRP and cromakalim were given after H2O2/FeSO4 exposure (Fenton's reagent was removed from the tissue bath), the observed relaxations were markedly diminished. The effects afforded by the early exposure to H2O2/FeSO4 reaction of the preparations were significantly protected by catalase (100 U/ml, H2O2 scavenger), dimethylthiourea (1 mM, H2O2 and HO. scavenger), dimethyl sulfoxide (100 mM, HO. scavenger), deferoxamine (1 mM, a powerful iron chelator) and by a cocktail of catalase-deferoxamine. Generation of HO. from H2O2/FeSO4 was studied by electron spin resonance spectroscopy using the spintrap 5,5-dimethyl-1-pyrroline-N-oxide. We found that H2O2/ FeSO4 reaction formed a 1:2:2:1 quartet, characteristic of the HO-5,5-dimethyl-1-pyrroline-N-oxide spin adduct. After exposure to capsaicin (10(-5) M) or H2O2/FeSO4 of the artery ring preparations, the intensity of CGRP-like immunoreactivity of the periarterial nerves was reduced drastically; the relaxation caused by the nerve stimulation was nearly fully inhibited by capsaicin and H2O2/FeSO4 reaction. The relaxant response, however, to nitroglycerin (10(-5) M) in the presence of norepinephrine to induce tone was unaffected by the early H2O2/ FeSO4 exposure. The data obtained from the present study indicate that HO., rather than H2O2, is the active agent in CGRP-mediated neurogenic relaxation. It is suggested that the HO. can deplete endogenous CGRP localized prejunctionally and also damage CGRP-induced relaxation of canine lingual artery preparations that is caused by activation of ATP-sensitive K+ channels at postjunctional sites. It is also postulated that the second messenger system of the relaxation mediated, at least, by cyclic GMP may be less susceptible to HO..