Transformation of monomer aluminate ions from tetrahedron to octaheron

1　INTRODUCTIONTheBayerprocessfortheproductionofaluminafrombauxiteinvolvesa perennial gibbsite (γ Al(OH ) 3) precipitationstep ,relatingtoaninherentlyslowcrystalgrowthfromsupersaturatedsodiumalu minatesolution .Accordingtoexperimentalre sults[1,2 ] ,thetetrahedral [Al(OH ) 4]- ionisthedominantspeciesincausticaluminatesolutionwhilethebasicgrowthunitofgibbsiteprecipitatingincaus ticaluminatesolutionisoctahedral [(H2 O ) 2 Al(OH ) 4]- ,thetransformationof [Al(OH) 4]- into[(H2 O) 2 Al(…     

铝酸钠溶液中离子溶剂化作用

应用量子化学从头算密度泛函理论以及DFT/COSMO溶剂模型,基于 UHF/BLYP/DNP水平对高苛性比中等浓度铝酸钠溶液中各类离子(分子)的溶剂化作用进行研究.根据离子(分子) 的几何构型、总能量、振动频率、相关热力学数据以及相应的水合自由能,对溶液中离子(分子)的存在形式以及不同离子(分子)间的平衡转化关系进行分析.结果表明,在高苛性比中等浓度铝酸钠溶液中,铝主要是以水合Al(OH)-4离子和Na(H2O) 6Al(OH)-4离子对形式存在,同时还存在有中性水合分子Al(OH)3H2O.     

Influence of supersaturation on structure of sodium aluminate solutions with medium concentration:a solution X-ray diffraction study

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｏｕｇｈｍａｎｙ ｐｏｗｅｒｆｕｌａｎａｌｙｔｉｃａｌｔｅｃｈｎｉｑｕｅｓｗｅｒｅｐｅｒｆｏｒｍｅｄｏｎｓｏｄｉｕｍａｌｕｍｉｎａｔｅｓｏｌｕｔｉｏｎ[1～ 4 ] ,ｔｈｅｙｓｔｉｌｌｈａｄｓｏｍｅｌｉｍｉｔａｔｉｏｎ .Ｘ ｒａｙｄ     

热历史对铝酸钠溶液中含铝离子之间转化的影响

为了优化拜耳法生产氧化铝的过程,有必要明晰热历史对铝酸钠溶液中含铝离子间转化的影响。通过对不同组成铝酸钠溶液经过热处理、稀释和浓缩后其红外谱图的测定,研究溶液中含铝离子间的转化规律。结果表明：升高温度和延长保温时间有助于Al2-2O（OH）6离子向880 cm-1波数处Al—OH结构四面体聚合物和Al（OH）-4转化;稀释过程中快速发生A12O（OH）2-6和Al—OH结构四面体聚合物向Al（OH）-4的转化,但稀释后溶液可发生Al（OH）-4向Al—OH结构四面体聚合物的恢复性转化;浓缩过程则发生Al（OH）-4向Al—OH结构四面体聚合物和A122O（OH）2-6的转化,且向A12O（OH）-6的转化较困难。     

三水铝石在氢氧化钠溶液中的平衡溶解度热力学模型(英文)

针对拜耳法生产氧化铝过程中最为重要的NaAl(OH)4-NaOH-H2O体系,构建三水铝石溶解于氢氧化钠溶液的反应平衡常数的理论模型,并得出电解质NaAl(OH)4新的Pitzer模型参数和NaOH-NaAl(OH)4-H2O体系的热力学混合参数(温度范围298.15～373.15K)。将所得模型和参数对NaAl(OH)4-NaOH-H2O体系进行适用性分析。结果表明:将该理论模型用来计算三水铝石溶解反应的平衡常数是适用且准确的;电解质NaAl(OH)4的Pitzer模型参数β(0)(NaAl(OH)4)、β(1)(NaAl(OH)4)和CΦ(NaAl(OH)4),Al(OH)4-与OH-的二离子相互作用参数θ(OH-Al(OH)4-),以及Al(OH)4-与OH-和Na+的三离子相互作用参数ψ(Na+OH-Al(OH)4-)均与温度相关;当温度在298.15～373.15K时,预测三水铝石溶解于氢氧化钠溶液的平衡溶解度是可行的。     

Kinetics of crystal growth on seeded precipitation of sodium aluminate solutions with new device

A new device was designed, which can effectively avoid the undesired nucleation and agglomeration of fine particles on the experimental results during the seaded precipitation of sodium aluminate solution, and moreover, the experimental conditions are nearly kept constant during the experiment. With the new device, it is proven that a good result can be obtained on the kinetics study of the crystal growth in seeded precipitation of sodium aluminate solution. Experiments were carried out with the concentration of Na2O (Nk)170 g/L, the mole ratio of Na2O to Al2O3(ak) all between 1.52 to 2.01, at 65, 70, 75℃, respectively. And the kinetics equation of crystal growth of gibbsite was deduced.     

高苛性比铝酸钠溶液的Raman光谱研究SCIEI

用 Raman光谱方法研究高苛性比铝酸钠溶液的阴离子组成.高苛性比的铝酸钠溶液的Raman光谱在470cm^(-1)等处有特征峰.和固体Ca_3[Al(0H)_6]_2及Ba_2[Al_2-(OH)_(10)]的 Raman谱相对照,可看出高苛性比的浓铝酸钠溶液可能含有Al(OH))_6^(3-)及其聚合离子。     

种分制备超细氢氧化铝中碱含量的变化(英文)

种分氢氧化铝中碱含量变化规律关系到氢氧化铝的质量和碱耗,通过测定溶液浓度和电导率、氢氧化铝中碱含量和粒度分布以及分析粒子形貌,研究种分氢氧化铝中碱含量的变化规律。结果表明,溶液组分浓度高、球磨晶种循环、种分温度低、初始分解速率快或产品比表面积大都会导致氢氧化铝中碱含量升高;在低硅铝酸钠溶液种分过程中,粒子的附聚得到抑制,超细氢氧化铝中碱主要以晶格碱形式存在,以钠硅渣形式存在的碱含量极低;同时,升高初始分解温度,晶种老化,降低分解速率,延长种分时间,都有利于产品中碱含量的降低。结果还表明:种分过程中,Na+Al(OH)4离子可能对产品中碱含量有很大的影响。     

铝酸钠和含硅铝酸钠溶液的红外光谱和拉曼光谱

应用红外光谱和拉曼光谱系统地研究了苛性比ak＝1．55，A12O3含量分别为100g/L，150g/L和200g／L的铝酸钠溶液和含硅铝酸钠溶液。结果表明：溶液中存在A1-O—Al键，且随着A12O3含量增加而增多；SiO2的存在使得铝酸钠溶液中A1-O—Al键转化为A1-O—Si键，随着SiO2含量增加，A1-O—Si键增多。这表明A1-O—Si键比A1-O—Al键更稳定。因此，含硅铝酸钠溶液是由A1-O—Al，A1-O—Si，Si—O—si键和A1-O—H…O—Al氢键结合的成网络状无机高分子溶液，而不是过饱和的A12O3溶液。这是铝酸钠溶液稳定的原因。     

Al(OH)3种分过程的超声场强化

对超声场的处理方法，温度，功率，处理时间以及溶液浓度等一个因素进行正交实验，得出超声场强化种分反应的最佳条件和五个因素影响的顺序，在最佳的超声场强化条件，分解率为45％的分解时间由30h缩短至15h，反应的活化能由68kJ/mol降低到35kJ/mol，但是产品Al(OH)3的物相结构没有改变，另外，铝酸钠溶液的Raman光谱表明，在超声场处理后，二聚体Al2O(OH)^2-6完全解聚，部分Al(OH)^-4离子转变成了某种过渡态离子。     

RAMAN SPECTRA OF SODIUM ALUMINATE SOLUTIONS WITH HIGH-CAUSTIC RATIO AND HIGH CONCENTRATION

The constitution of high-caustic ratio and highly concentrated sodium aluminate solutions hasbeen investigated by Raman spectra method.By comparison with the Raman spectra ofcrystalline solids of Ca_3[Al(OH)_6]_2 and Ba_2[Al_2(OH)_(10)],it can be concluded thatAI(OH)_6~(3-)ion and perhaps its polymers may be formed in these solutions.     

熟料烧结过程中氧化铁反应行为的热力学分析

通过对Fe2O3与碳酸钠、氧化钙以及硅酸钙反应的热力学分析,明确Fe2O3在铝土矿炉料烧结过程中的热力学反应规律。热力学计算、分析结果表明:Fe2O3在正常烧结温度范围内能与Na2CO3或CaO发生反应,但更易与CaO反应形成2CaO.Fe2O3或CaO.Fe2O3,Fe2O3和Na2O.Fe2O3能使2CaO.SiO2和3CaO.2SiO2转变为CaO.SiO2,CaO.SiO2进一步与Na2O.Al2O3或Na2O.Fe2O3反应生成不溶的三元化合物而造成烧结法生产氧化铝过程中Na2O和Al2O3的损失。4CaO.Al2O3.Fe2O3不能由铁酸钙和铝酸钠相互反应产生,而可能是CaO、Al2O3和Fe2O3三者直接反应的产物,且在烧结条件下Na2O.Fe2O3可分解4CaO.Al2O3.Fe2O3。     

Combined effect of amino and carboxyl group in α-alanine on seeded precipitation of sodium aluminate solution

α-alanine was adopted as a new additive to elucidate the seeded precipitation mechanism of sodium aluminate solution. α-alanine has the inhibitory effect at the initial period of reaction, but the favorable effect in subsequent reaction. The combined effect of amino and carboxyl group in α-alanine was confirmed by investigating the effect of propionic acid, ethamine and the mixture of propionic acid and ethamine (mole ratio 1:1) on the precipitation of sodium aluminate solution, respectively. The inhibitory effect derives from the adsorption of amino or carboxyl group in α-alanine on the active surface sites of gibbsite, which was confirmed by the alleviating inhibitory effects of propionic acid, ethamine and α-alanine due to the double crystal seed mass. The semi-quantitative IR spectrum analysis of the relative concentrations of Al2O(OH)62- with the band at about 550 cm-1 and polynuclear aluminate ion with the bands at about 880 cm-1 and 635 cm-1, indicates that the dynamic balance among some aluminate species present in sodium aluminate solution is broken due to the addition of α-alanine, thus resulting in the change of the seeded precipitation ratio of sodium aluminate solution.     

COMPOSITION AND SPECTROSCOPIC STUDIES OF HYDRATED SODIUM ALUMINATE COMPOUNDS

ＣＯＭＰＯＳＩＴＩＯＮＡＮＤＳＰＥＣＴＲＯＳＣＯＰＩＣＳＴＵＤＩＥＳＯＦＨＹＤＲＡＴＥＤＳＯＤＩＵＭＡＬＵＭＩＮＡＴＥＣＯＭＰＯＵＮＤＳＱＩＵＧｕｏｆａｎｇ,ＤＥＮＧＨｏｎｇｍｅｉ,ＺＥＮＧＷｅｎｍｉｎｇａｎｄＣＨＥＮＨｉａｎｙｉ（ＳｈａｎｇｈａｉＩ...     

热浸锌铝合金镀层表面纳米晶腐蚀产物共沉积机理

采用XRD和TEM对热浸锌铝合金镀层在动态充气海水全浸试验时所形成的白色腐蚀产物进行了研究,结果表明：腐蚀产物主要由典型的纳米级Zn4CO3(OH)6.H2O,Zn5(OH)8Cl2和Zn6Al2CO3(OH)16.4H2O微晶组成,而这种纳米晶的形成与由吸附引起的Zn^2 和Al^3 离子的共沉积有关,镀层表面腐蚀后首先生成Al(OH)3凝胶,当凝胶吸附的锌离子超过异相核的临界过饱和度时,发生锌、铝氢氧化物的共沉淀,生成双氢氧化物,由于晶体长大速度较慢不能与沉淀形核同步进行,导致镀层表面形成了微晶状态的腐蚀产物。     

Ca2SiO4和NaFeO2的反应和铝酸盐熟料配方的优化

用X射线衍射(XRD)和红外吸收光谱(IRS)研究了Ca_2SiO_4—NaFeO_2系的反应产物,证明其中含CaFe_2O_4和Na_4Ca_8(SiO_4)_5。热力学计算表明Ca_2SiO_4-NaFeO_2不是互易系的稳定对Na_4Ca_8(SiO_4)_5和铝酸钠溶液作用生成Ca_3[Al(OH)_6]_2(或其固溶体),使熟料Al_2O_3溶出率降低。用模式识别方法从工业生产技术记录中总结出熟料配方优化数学模型,并给出理论解释。     

Relationship between Al(OH)3 solubility and particle size in synthetic Bayer liquors

Surface tension of sodium aluminate solution and the contact angle between Al(OH)₃ particles and aluminate solution were measured, then the dependence of Al(OH)₃ solubility on its particle size was calculated and thus the variation of the critical nucleus sizes was determined based on the Ostwald ripening formula. The results show that the Al(OH)₃ solubility in sodium aluminate solution decreases with the increment of particle size, and the critical nucleus sizes increase with the rise of alkali concentration, caustic ratio and precipitation temperature. The results also imply that the presence of small particles in seeded precipitation system is an important factor to limit the depth of precipitation.     

醚类添加剂B35对铝酸钠溶液晶种分角过程的影响

研究醚类添加剂B35对铝酸钠溶液晶种分解过程的影响,采用红外光谱仪分析溶液的结构,采用微电泳仪测定Al(OH)3颗粒表面的Zeta电位.结果表明:加入适量醚类添加剂可强化分解过程,当添加剂B35用量为500mg/L时,相对空白样可提高分解率4%;醚类添加剂B35对分解过程的强化不是山铝酸钠溶液结构的改变引起的;添加剂B35可使Al(OH)3晶种表面Zeta电位明显升高,说明Al(OH)3对该表面活性剂发生特性吸附,导致铝酸钠溶液在Al(OH)3颗粒表面的润湿角减小,其固液界面张力降低,从而使分解过程得以强化;此外,醚类添加剂B35使产品Al(OH)3半均粒径增大10 μm左右,而粗颗粒在溶液中的平衡溶解度较小,分解过程推动力较大,也应是强化分解过程的原因之一.     

Structure and bonding orientation of favorable growth unit Al6（OH）18（H2O）6 of gibbsite

1INTRODUCTION Thecrystalgrowthcharacteristicsofgibbsite insupersaturatedsodiumaluminatesolutionwere extensivelyinvestigated[15],butthestructureand formofthegrowthunitwerenotrelated.Firstly,Vanstratenetal[6]indicatedthatthegrowthunit transitionstateofaluminateacidradicalexistedin thecrystallizationofgibbsitefromalkalinesodiumaluminatesolution.Parkinsonetal[7]figuredout thatAl(OH)-4,Al(OH)2-5andAl(OH)3-6would belikelytobecomegrowthunitsofgibbsitefromtheviewpointofcrystalsurfacebindingene…     

柠檬酸盐水溶液中二价钴的电化学还原过程（英文）

采用循环伏安法(CV)和电化学交流阻抗法(EIS),研究不同柠檬酸盐浓度和pH下钴的电化学还原过程。结果表明:在组成为0.05 mol/L CoSO4·5H2O、0.20 mol/L Na2SO4和0~0.40 mol/L C6H5O7Na3·2H2O,pH为3~9的溶液中,二价钴以游离Co2+离子和[Co(C6H5O7)]配合物两种形态存在,并在电极表面被还原。溶液的pH对钴的电化学还原过程有显著的影响。当柠檬酸盐溶液的pH为3时,钴主要以游离Co2+离子的形态被还原;当溶液为弱酸性(pH=4~6)时,钴主要以[Co(C6H5O7)]-的形态被还原为Co0,还原过程分两步进行,中间产物在电极表面发生吸附;当柠檬酸盐水溶液的pH大于7时,形成的柠檬酸钴配合物主要是[Co(C6H5O7)]-和[Co(C6H4O7)]2-,这两种配合物非常稳定,其还原电位负于溶液的析氢电位,因此难以从该溶液中还原得到Co0。