铝酸钠溶液种分过程的粒度变化规律研究

以Master-2000型激光粒度仪测定的粒度分布为基础,考察了种分过程中2μm和20-30μm粒径粒子总质量(Wt)随时间(t)的变化关系.分析了铝酸钠溶液种分过程的二次成核与苛性比(n x)、初始晶种量以及温度的关系,发现成核过程主要在种分前期进行,后期细颗粒因长大和附聚会减少,随温度升高,75℃下溶液几乎没有明显成核;20-30μm的粒子变化在α K较低的情况下(1.3),远大于相同初始晶种量的高α x铝酸钠溶液,表明可能其主要由附聚得到.     

过饱和铝酸钠溶液结构性质与分解机理研究现状*

过饱和铝酸钠溶液分解是氧化铝生产过机理的研究是氧化铝生产过程的重要基础问题.本文对过饱和铝酸钠溶液中铝酸根离子存在的基本形态,浓度、苛性比和阳离子对铝酸钠溶液结构性质的影响,溶液中多种铝酸根离子平衡与转化规律,以及铝酸钠溶液分解机理研究的现状进行了总结和评述;分析了现有铝酸钠溶液结构性质与分解机理研究的不足;围绕强化氧化铝生产中铝酸钠溶液分解过程的目的,提出了铝酸钠溶液结构性质与分解机理研究的重点.     

电导法研究过饱和铝酸钠溶液均相成核过程

采用自行研制电导在线跟踪仪, 配套特制的传感器式电导电极, 研究铝酸钠溶液均相成核过程中溶液电导变化规律, 及溶液过饱和度对反应诱导期作用; 通过测定铝酸钠溶液均相成核过程诱导期, 结合溶液均相成核理论, 测得323 K下, 饱和度S>3.8的铝酸钠溶液均相成核过程中的表观反应级数n=4±1, 固-液界面能γ=(40.6±2.0) mJ·m-2, 并据此估算临界成核粒径rc=(1.1±0.2) nm. 研究结果与文献值吻合, 证明该套仪器具有较高的灵敏度和可靠性.     

酸碱滴定法测定铝酸钠溶液中总碱

在烧结法生产氢氧化铝工业中,从脱硅精液中析出氢氧化铝是采用向其通入二氧化碳气体即碳酸化分解的方法。分解后溶液的主要成分为碳酸钠,经蒸发或者加入适量纯碱(补碱)返回用于配制生料浆[1]。采用生产氢氧化铝的新技术[2],碳酸分解母液加入适量纯碱后,不是返回用于配制生料浆,而是作为浸取液直接用于烧结熟料的浸取。由于浸取液中碳酸钠的浓度直接影响烧结熟料中氧化铝的浸取率,为此有必要准确测定碳酸分解母液中总碱的含量,以确定补碱量,适应生产的需要。目前常用于测定铝酸钠溶液中总碱的方法是在试样溶液中加入过量的EDTA(掩蔽Al3 )及…     

铝酸钠溶液中超声诱致自由基的检测

文首次应用自由基捕获方法和电子顺磁共振技术(EPR),检测铝酸钠溶液在超声波空化作用下产生的羟自由基.本实验利用DMPO捕获羟自由基而生成寿命较长的DMPO-OH这一特性,分析了超声输出功率、超声处理时间等对DMPO-OH的自旋共振谱图中对称振动峰强弱的影响.实验结果表明:当超声输出功率达到或超过空化阈值,过饱和中等浓度铝酸钠溶液中水分子可裂解为羟自由基和氢原子自由基;同时自由基的产量与超声输出功率、超声作用时间以及溶液浓度有关.     

铝酸钠溶液的紫外吸收峰

分别用量子化学MNDO和DV-X_α方法计算了二聚铝酸离子[Al_2O(OH)_6]~(2-)和Al(OH)_4~-。结果表明前者旋转势垒很低, 只有10.08 kJ·mol~(-1), 最稳定平衡构型为C_s。用X_α过渡态理论计算获得这两个离子紫外吸收峰的理论值分别为266.6 nm和234.4 nm, 与实验值270.0 nm和230.0 nm相当接近。因此可以认为, 紫外吸收峰270.0 nm和230.0 nm分别为[Al_2O(OH)_6]~(2-)和Al(OH)_4~-离子的最高占有轨道电子向最低空轨道跃迁时产生的吸收峰。计算结果支持铝酸钠溶液中存在二聚铝酸离子的观点。     

铝酸钠溶液中析出一水软铝石过程的宏观动力学

对铝酸钠溶液中析出一水软铝石过程的宏观动力学进行了研究.在考虑主要影响因素的前提下,提出了动力学模型,并通过线性回归计算出方程的参数,给出了相应的动力学方程.研究结果表明:分解反应对A l2O3过饱和度和游离NaOH浓度的反应级数分别为2.24和-2.24,前者与大多数研究者的结论一致,而后者则说明溶液中游离NaOH是对反应影响较大的动力学制约因素;反应的表观活化能为62.248 kJ/mol.     

铝酸钠溶液的鲁米诺增强声致发光研究

Ultrasonic processing on sodium aluminate solutions was proved to have effects on the gibbsite crystallization process from sodium aluminate solution. In order to investigate the mechanism of the ultrasonic intensification, the sonofluorescence spectrum was detected by fluorescence spectrometer in sodium alumiante Luminol solutions, and the spectrum under the conditions of various ultrasonic power and different composition of sodium aluminate solutions were studied. It is found that the sodium aluminate Luminol solution can irradiate fluorescence by ultrasonic processing above the given power; the intensity of sonofluorescence are relatively low in sodium aluminate solutions with high concentration and low αk（mol ratio of Na2O/Al2O3 in sodium aluminate solution）. The relationship between the sonofluorenscence and ultrasonic intensification on gibbsite crystallization process from sodium aluminate solutions were also discussed. The conclusion that the ultrasonic effects are influenced by ultrasonic cavitation and intensity of sonofluorescence spectrum is deduced.     

超声场强化氢氧化铝结晶过程的研究

研究了超声场对拜耳法种分过程的强化效果，发现20kHz，33kHz两种频率的超声场都可以大幅度地提高种分的分解速度，将分解率为45%的时间由30h缩短至15h。不同频率的超声场对氢氧化铝结晶过程影响的具体方式不同。20kHz促进颗粒的附聚和长大过程，提高产品的平均粒度3.7μm；33kHz超声场更有利于二次成核过程。两种频率的超声场都不影响铝酸钠溶液的一次成核。     

铝酸钠和含硅铝酸钠溶液结构和性质的研究

本文通过对铝酸钠和硅铝酸钠溶液的红外光谱、拉曼光谱、粘度、表面张力、丁达尔现象和聚沉等光谱和物理化学性质的研究测定,分析了硅在铝酸钠溶液中的行为.认为硅主要是取代Al-O-Al结构中的Al,形成Al-O-Si结构和Al-O-Si-O-Al-O结构等多种形式硅氧铝键以及由氢键相连的大分子结构.这种结构直接影响其物理化学性质,表现为随硅含量增加表面张力增加,粘度上升,具有丁达尔现象等.说明含硅铝酸钠溶液中存在大分子的胶性基团,属于无机高分子溶液,这种网络状"大分子"结构是硅铝酸钠溶液稳定的原因.     

Studies on the Anionic Species of Sodium Aluminate Solutions

Raman, UV, IR and NMR spectra, activity measurement and quantum chemical calculation methods are used concurrently to study the anionic species of sodium aluminate solutions. It has been found that sodium aluminate solutions with the same composition but different preparative histories may exhibit quite different optical andNMg spectra.Sodium aluminate solutions contain a series of aluminium-containing anions including Al(OH)_4~-,Al(OH)_6~(3-) and [(HO)_3Al-O-Al(OH)_3]~(2-).They may convert into each other but the reactions may be rather slow,so that solutions with the same composition but different preparative histories may have different ratios between various anions, and exhibit different spectroscopic properties.     

SB粉水热种分过饱和铝酸钠溶液制备拟薄水铝石

A novel hydrothermal process for preparation of single-phase pseudoboehmite from supersaturated sodium aluminate solution with SB pseudoboehmite seed was presented. The process is characterized by precipitation for 3 h at temperature around 125 ℃ with a seed ratio of 1.0. Precipitation yield of Al₂O₃ over 20% could be reached and the specific surface area of precipitated products almost as high as SB seed could be obtained. The process suitable for preparing pseudoboehmite with any pseudoboehmite seed in principle comprises a highly variation of the current Bayer process and the latest boehmite process for the production of smelter grade alumina.     

溶胶-凝胶法制备纳米氢氧化铝溶胶

研究了利用铝酸钠溶液碳酸化产生的沉淀, 经胶溶作用制备出纳米氢氧化铝溶胶的过程. 分析了铝酸钠溶液滴加到大量碳酸氢钠溶液中时发生的反应. X射线衍射研究结果表明, 在纳米氢氧化铝溶胶制备过程中, 从无定形氢氧化铝沉淀到拟薄水铝石的晶型转变过程是氢氧化铝沉淀胶溶时溶解再析出的过程. 将碳酸氢钠加入到苛性比为1.7的铝酸钠溶液中, 中和至苛性比为1.3后, 溶液诱导期中的紫外光谱显示270 nm处的Al(OH)3-6吸收增强. 经与含铝原子六配位的晶体紫外光谱对比后表明, 在铝酸钠分解生成氢氧化铝的过程中, 其铝的配位结构从四配位转化为六配位. 拟薄水铝石溶胶粒子的形貌与胶溶所用的酸和分散剂有关.     

聚酰胺―胺的合成表征及对铝酸钠溶液物化性质的影响

用发散法合成以乙二胺为核的聚酰胺―胺(PAMAM 0.5～6.0代),采用元素分析、电位滴定等方法对合成产物进行表征分析,考察了不同分子代数、不同浓度的PAMAM对铝酸钠溶液表面张力和电导率等物理化学性质的影响。结果表明,该条件下合成的PAMAM具有较好的结构完整性。此外随着添加剂PAMAM的增加,铝酸钠溶液的表面张力急剧降低,半代数的PAMAM具有较好的表面活性,有望成为新一代的表面活性剂;整代数的PAMAM也有一定的表面活性。PAMAM属于非离子型表面活性剂,因此随着PAMAM的加入,铝酸钠溶液的电导率改变不大。     

Comprehensive Model of Synthetic Bayer Liquors. Part 3. Sodium Aluminate Solutions and the Solubility of Gibbsite and Boehmite

Summary. A Pitzer model representing the thermodynamics of alkaline sodium aluminate solutions is presented. It constitutes a key part of our 10-component synthetic Bayer liquor model communicated in this series of papers. The present model calculates thermodynamic properties, such as heat capacities, osmotic coefficients, and densities, of these solutions as well as the solubilities of gibbsite and boehmite over temperature and concentration ranges of industrial interest.     

Studies on the Preparation and Properties of Organic Acid Aluminate Linked Polyacrylamide

The organic acid aluminate (AlOA) was used as a linked agent to enhance the viscosity of partially hydrolyzed polyacrylamide (HPAM) solution. The influencing factors, such as HPAM concentration, pH, temperature, and salinity on the linked polymer system were probed via the investigations on rheological properties, microstructure, and location of the linked polymer systems. The result show that the scattered gelatin particles are contained in the linked polymer network structure. The system behaves as mainly elasticity, and the system belongs to the linear viscoelastic fluid. For the solution with elasticity, its subsequent fluid not only has a boost effect on the front fluid, but also the front fluid has a stronger effect of “drawing” and “dragging” on its side and subsequent fluid. Therefore, it will be important in both theory investigation and the actual oil recovery.     

硅铝酸钠溶液中27Al和29Si的核磁共振研究

本文采用原位核磁共振方法检测不同碱度硅铝酸钠溶液中²⁷Al的信号, 在比较了文献实验结果的基础上, 明确了体系中的不同铝物种的化学位移, 进一步提出了硅铝酸钠溶液中的硅铝物种的归属.