铝酸钠溶液中氧化铝的自动快速分析

采用流动注射微量滴定分析方法，通过铝酸钠溶液分析仪，研究了以碘基水扬酸（SAL）为滴定剂，NaF为络合剂及酚酞为指示剂时，自动分析铝酸钠溶液中氧化铝含量的方法，探讨了滴定剂浓度，采样体积，管道内径及长度，共存元素的影响，推测了NaF与SAL－Al(OH)3的络合比例。     

Preparation of Al(OH)3 by ion membrane electrolysis and precipitation of sodium aluminate solution with seeds

The preparation of Al(OH)3 by the ion exchange membrane electrolysis followed by the precipitation of sodium aluminate solution with seeds was made. During the process of ion membrane electrolysis, the sodium aluminate solution is rapidly acidified and the caustic ratio (aK) is decreased due to oxygen evolution in the anodic region. And the causticity of solution is increased due to hydrogen evolution in the cathode region, producing the high concentration of caustic soda solution. Regulating the acidity of the anodic solution by controlling the electric quantity in the electrolysis and subsequent decomposing the solution, Al(OH)3 could yield with very large rate and high efficiency. The experiments also indicate that the quality of aluminum hydroxide product is greatly affected by the impurity silicon.     

铝酸钠溶液添加活性晶种分解过程颗粒的演变

以碳酸氢钠诱导铝酸钠溶液分解制备活性晶种,研究了添加极少量该活性晶种铝酸钠溶液分解过程中的颗粒演变规律。结果表明:随着分解过程的进行,产品粒度先增大而后减小,其拐点对应于铝酸钠溶液过饱和度变化速率由快变慢的转折点。种分初期,产品中拜耳石含量高,并存在数量较多的附聚体,拜耳石为粘结相。种分后期,拜耳石被较高苛性比的铝酸钠溶液溶解,导致附聚体解体而使产品细化。研究结果可为研究铝酸钠溶液添加活性晶种分解过程的粒度控制技术提供借鉴。     

高苛性比铝酸钠溶液中氧化铝的回收

对加入石灰后的高苛性比铝酸钠溶液中氧化铝的回收进行了研究。热力学计算结果表明,氧化钙较氢氧化钙更容易使铝酸钠溶液中的铝酸根离子转化为水合铝酸钙,使铝酸钠溶液的平衡苛性比能达到很高的值;水合铝酸钙随着温度的升高,稳定性降低,因而能在拜尔法高温溶出过程中分解以代替石灰,并回收其中的氧化铝。实验结果表明,影响水合铝酸钙形成因素的大小顺序为：温度≈碱浓度＞ＣａＯ／Ａｌ２Ｏ３＞时间。     

Behavior of calcium oxalate in sodium aluminate solutions

The stability of calcium oxalate is critical for the removal of sodium oxalate from sodium aluminate solutions. This study investigated the behavior of calcium oxalate in sodium aluminate solution containing sodium carbonate. Results show that calcium oxalate can be converted to tricalcium aluminate hydrate (TCA) and calcium carbonate in sodium aluminate solution and sodium carbonate solution, respectively. Elevating temperature, extending residence time, or increasing caustic soda concentration enhances the conversion ratio of calcium oxalate in sodium aluminate solution; as a consequence, anti-causticisation occurs. Stability of calcium-containing compounds in sodium aluminate solution containing sodium carbonate differs from that in sodium aluminate solution or sodium carbonate solution. Na₂CO₃ in aluminate solution accelerates the transformation of calcium oxalate; thus, alumina is lost because of 4CaO·Al₂O₃·CO₂·11H₂O and TCA formation. Calcium carbonate, 4CaO·Al₂O₃·CO₂·11H₂O and calcium oxalate can change into TCA in sodium aluminate solution at elevated temperature. Calcium oxalate remains relatively stable in dilute aluminate solution within a short residence time at low temperature. Thus, a novel process for removal of sodium oxalate by lime causticisation was presented and employed in an alumina refinery in China.     

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。     

1,2-辛二醇对铝酸钠溶液种分过程的影响

研究1,2-辛二醇对铝酸钠溶液种分过程的影响。结果表明,1,2-辛二醇通过吸附在晶种表面对铝酸钠溶液种分过程产生抑制作用。1,2-辛二醇的添加浓度、实验温度以及苛碱浓度等因素对1,2-辛二醇改善铝酸钠溶液种分效果具有显著影响。添加浓度小于1.25 mmol/L时,1,2-辛二醇对铝酸钠溶液的抑制程度很小;添加浓度超过1.5 mmol/L,抑制作用非常明显。温度越低,苛碱浓度越大,1,2-辛二醇对铝酸钠溶液分解抑制作用越大。     

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     

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.     

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.     

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。     

用拉曼光谱研究超声波对铝酸钠溶液的影响

为了揭示超声强化铝酸钠溶液种分过程的机理，本文运用拉曼光谱分析研究了超声波对铝酸钠溶液结构性质的影响，用硝酸钠作外标对铝酸钠溶液经超声作用后Al（OH）4^-的变化进行了定量研究，研究表明，超声波作用可使铝酸钠溶液的结构向有利于分解的方向转变；只有在超声功率超过一定值，铝酸钠溶液的苛性碱浓度及ak（铝酸钠溶液中Na2O／Al2O3的摩尔比）在一定范围之内，超声波才能使铝酸钠溶液结构发生明显变化。     

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.     

Low-temperature phase transitions of sodium aluminate solutions

A series of low-temperature phase transitions of sodium aluminate solutions were studied by differential scanning calorimetry (DSC) and Raman spectroscopy. The results indicate that NaOH concentration is a primary impact factor for the binary eutectic point and ice melting temperature of sodium aluminate solutions with low NaOH concentration. In addition, the phase transition process of sodium aluminate solutions with low NaOH concentration from 123.15 to 283.15 K is divided into four steps: non-crystal to crystal, ternary eutectic reaction, binary eutectic reaction and ice melt. The projection phase diagram of NaOH-Al(OH)₃-H₂O system at low temperature was plotted, in which the ternary eutectic temperature for sodium aluminate solutions is 183.15 K.     

SiO_2在铝酸钠溶液中存在状态的研究SCIEI

用Raman光谱和紫外光谱研究了不同方法制备的含SiO_2的铝酸钠溶液,并与工业熟料的溶出液进行了对比。SiO_2的存在状态随制备方法而异。工业熟料的溶出液含有带Si-O-Si结构的聚硅酸离子。     

全自动温度滴定仪在氧化铝生产过程控制分析中的试验与应用

本文将利用滴定过程化学反应所产生的温度变化来确定滴定等当点的全自动温度滴定仪应用于拜耳法生产氧化铝流程铝酸钠溶液中氧化铝、全碱和苛碱含量的测定,并同人工滴定分析结果进行了对比.试验结果表明,在不同浓度下用温度滴定仪测定铝酸钠溶液成分的数据重现性均较好,完全符合正态分布,可以做显著性检验,与人工滴定分析数据没有显著性差异;对于同一种溶液样品,两种分析方法的数据对应性较好,最大差值不超过2g/l,结果符合要求,能够满足生产控制分析的需要.     

ANIONIC SPECIES OF SiO_2-CONTAINING SODIUM ALUMINATE SOLUTIONS

The anionic species of the SiO_2-containing sodium aluminate solutions prepared by differentmethods have been investigated by Raman spectra and ultraviolet spectra.It was found thatthese solutions have different SiO_2-containing anions.The solution prepared by leaching in-dustrial sinter of soda-lime sintering process contains polvsilicate ions with Si-O-Si radicals.     

Mineral transition of desilication products precipitated in synthetic sodium aluminate solution under atmospheric pressure

The liquor concentration, mineral proportion, crystal parameters and micro morphology of various desilication products (DSPs) precipitated in silica-supersaturated sodium aluminate solution at 95 °C under different reaction conditions were systematically researched. The DSPs formed under atmospheric pressure comprise amorphous phase, zeolite A, zeolite and sodalite, and the DSPs concentration and crystallinity increase with the increase of initial silica concentration, initial molar ratio of caustic Na₂O to Al₂O₃ (α_K) and desilication duration. Decreasing the initial silica concentration, initial α_K and increasing the desilication duration can reduce the proportion of zeolite A. The zeolite and sodalite are the stable DSPs, while the precipitation of zeolite A occurs at a high silica-supersaturated state in sodium aluminate solution. The DSPs are precipitated in the form of agglomerates, but the morphologies of various DSPs are quite different. Both the molar ratios of Na₂O to Al₂O₃ and SiO₂ to Al₂O₃ in DSPs increase with the increasing desilication duration, resulting in the increase of the cell volumes of various DSPs. The precipitation sequence of DSPs under atmospheric pressure is: amorphous phase→zeolite A→zeolite→sodalite.     

高白填料氢氧化铝色度影响因素

综述了各种因素,如高白氢氧化铝产品的粒度、铝酸钠溶液的质量、碳分二氧化碳气体质量、氧化铝洗涤工艺等,对高白氢氧化铝粉体色度的影响。在生产高白氢氧化铝时首先要保证原材物料的稳定和纯净,其次要制备出合适的粒度和粒度分布。     

温度对离子膜电解种分铝酸钠溶液影响的研究

本工作研究了温度对离子膜电解及种分铝酸钠溶液的影响,在研究不同温度下电解相同铝酸钠溶液的过程中,掌握了电流、电解时间与温度的关系。用相同的晶种和晶种系数种分离子膜电解的铝酸钠溶液时,发现了温度对分解率的影响规律,分析得到较佳的电解和种分温度。通过对产品粒度的分析,得出较高温度更有利于附聚,产品粒度大的结论。