响应曲面法对铝灰中AlN的水解行为

铝冶炼过程中会产生大量铝灰,铝灰中AlN对其综合利用和安全处置会产生显著影响。在系统分析AlN水解热力学基础上,以再生铝生产过程中产生的铝灰为原料,运用Design Expert软件设计二次正交旋转试验,研究铝灰中AlN的水解特征。结果表明:在303~373 K的温度范围内,铝灰中AlN的水解自发进行;液固比和水解时间对水解p H影响显著(P0.01);水解温度和液固比间的交互作用影响明显(P0.01)。水解p H值与水解温度、液固比和水解时间的二次回归方程理论预测值与试验值相对误差仅为1%,可以用来预测和指导铝灰中AlN水解行为。     

铝灰渣中AlN水解行为及其多元非线性回归分析

通过对铝灰渣水解反应过程中组分及其含量变化的研究,提出铝灰渣中AlN含量的修正公式;根据AlN含量和悬浊液pH值的测定,考察时间、温度、转速等水解参数对AlN水解速率的影响并对其进行多元非线性回归分析。结果表明:升高温度能降低铝灰渣中AlN含量并降低悬浊液pH值;延长时间可有效促进AlN的水解,同时在2h内悬浊液pH值迅速提升至高位;转速对AlN水解速率和悬浊液pH值无明显影响。总体而言,AlN含量比悬浊液pH值更能客观表征铝灰渣中AlN水解速率。对水解参数及修正后铝灰渣中AlN含量进行多元非线性回归分析并二次简化,发现理论值与实验值相对误差≤±8.65%。     

二次铝灰水解渣分质利用研究

二次铝灰是一次铝灰回收金属铝产生的危险废物,我国二次铝灰年排放量超过400万吨,目前通常采用水解技术进行脱氮预处理,但水解渣利用难度较大.针对上述问题,本文提出了二次铝灰水解渣温和碱溶-稀酸除杂-成型烧结回收活性铝并制备耐火材料骨料的利用工艺,系统考察了温和碱溶过程和稀酸除杂过程中反应时间、温度、浓度等因素对铝溶出率以...     

铝灰在铝电解槽上的添加应用研究

介绍了铝灰的成分,通过在铝电解槽的添加试验,发现了铝灰能够使铝液中硅升高、炉底沉淀增加、电压升高等问题.     

铝灰的回收利用现状及发展趋势

铝灰中含有金属铝及其它有价成分，文章对国内铝灰的回收处理方法、发展趋势及二次铝灰、弃灰的利用作了简要介绍。     

铝灰的回收利用现状及发展趋势

铝灰中含有金属铝及其它有价成分,文章对国内铝灰的回收处理方法、发展趋势及二次铝灰、弃灰的利用作了简要介绍.     

铝灰管理的艺术

人们一般认为铝灰的产生应当保持最少的数量，同时又十分看重铝灰中铝含量最大化的重要性。一些人错误地认为，低的铝含量是一件好事情。其实铝一直留在炉子中，由于冷却和铝热反应不充分，铝实际上已经损失了。     

铝循环二次铝灰生产氧化铝实验研究

铝循环过程中产生大量二次铝灰,未经妥善处理既污染环境又造成铝资源浪费.本文以铝再生熔炼过程产生的二次铝灰为原料,经水浸预处理、盐酸浸出、碱沉淀、纯化、再沉淀、焙烧等工艺制备高纯氧化铝.探讨了沉淀、纯化、焙烧的最佳条件,结果表明:加氨水调节pH至8.5,再加NaOH调至13,固液分离后,75℃下向滤液中加入聚乙二醇200...     

铝灰处理工艺研究

铝熔炼过程中产生的铝灰含铝量大约在45%-50%,有很高的利用价值。通过实验证明了通过铝灰热处理、球磨、中频炉熔炼等工艺,可回收铝灰中大部分金属铝,并将低含铝量的铝灰做成电解铝用阳极钢爪保护环,使铝灰循环利用,充分开发了铝灰的价值,减少了铝灰对环境的污染,并收到了较好的经济效益。     

Extracting aluminum from dross tailings

Aluminum dross tailings, an industrial waste, from the Egyptian Aluminium Company (Egyptalum) was used to produce two types of alums: aluminum-sulfate alum [itAl₂(SO₄)3.12H₂O]and ammonium-aluminum alum [(NH ₄)2SO₄AL₂(SO₄)3.24H₂O]. This was carried out in two processes. The first process is leaching the impurities using diluted H₂SO₄ with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of solute sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purifi ed aluminum dross tailings thus produced. The effects of temperature, time of reaction, and acid concentration on leaching and extraction processes were studied. The product alums were analyzed using x-ray diffraction and thermal analysis techniques.     

Evaluating the aluminum content of pressed dross

Pressing of skimmed hot drosses in a press is a very popular technology for cooling hot dross and obtaining the maximum in-house recovery of aluminum alloy. As a result of the pressing action, part of the molten aluminum alloy is squeezed out, while the rest of the free metal remains in the pressed skulls. Thus, pressed skulls are a valuable waste product, consisting of 30–70 wt.% free aluminum. Other constituents are aluminum oxide and oxides of alloying metals. Pressed skulls are generally valued on a free-metal recovery basis, which necessarily involves practical determination of their free aluminum content. Because most analytical methods are limited to the laboratory level and representative sub-samples, there is a practical interest in developing a routine, cost-effective, and non-destructive method to predict the free aluminum content in entire pressed skulls, based on their density. To develop such a method, a relation between the bulk density, porosity, and free aluminum content of pressed skulls was established. This article offers a review of those experiments and an analysis of their results.     

Recovering aluminum from aluminum dross in a DC electric-arc rotary furnace

The recycling of aluminum scrap and dross yields significant economic and energy savings, as well environmental benefits. The recovery of aluminum depends on many factors. The aim of this work is to experimentally investigate aluminum recovery under different conditions. In this study, aluminum dross was processed in a direct-current electric-arc rotary furnace. The presence of crushing refractory bodies during processing was found to increase the degree of aluminum recovery by about ten percent.     

Characterizing the physical and chemical properties of aluminum dross

In this article, the results of an investigation of granular and compact aluminum drosses are reported. The bulk density of granular drosses was determined according to DIN 52110-B, while DIN 52102-RE-VA was applied to compact drosses. The salt contents of the drosses were measured by applying the leaching test DIN 38414-S4; the metal contents by the salt-melting process were measured on a laboratory scale. In addition to the density data, the particle-size analysis, the distribution of elements in the different fractions, composition, metal content of recovered alloys, and gas evolution were compiled in a dross identity card characterizing each dross and simplifying the preanalysis for recovery.     

A salt-free treatment of aluminum dross using plasma heating

The plasma dross treatment process is similar in operation and equipment to the conventional RSF process, but its elimination of salt fluxes solves the problem of corrosive gas evolution, and also results in salt-free by-products (NMP), which are recyclable and are a marketable raw material for other industries. Labor and equipment demands are about the same for both processes, but the new process dispenses with the costs of salt purchase and landfilling or recycling of salt cake. The new process is the first industrial application of plasma heating technology in the aluminum industry, and greatly reduces environmental risks, while providing a closed-loop, pollution-and waste-free dross treatment method.     

Effects of AlN hydrolysis on fractal geometry characteristics of residue from secondary aluminium dross using response surface methodology

The effects of aluminium nitride (AlN) hydrolysis on fractal geometry characteristics of residue from secondary aluminium dross were studied using response surface methodology. The results show that the fractal dimensions of the residue can be significantly influenced by the AlN hydrolysis from secondary aluminium dross. The hydrolysis of AlN in the dross was spontaneous under temperatures of 303–373 K. The actual fractal dimensions of residue were significantly affected by the liquid–solid ratio (p<0.05) and changed from 1.16 to 1.80, which accurately aligned with those from the calculations. Moreover, the fractal dimensions of residue were significantly affected by the interactions between hydrolysis temperature and hydrolysis time, liquid–solid ratio and hydrolysis time, respectively (p<0.01). The minimum fractal dimensions of the residue reached 1.15 under the optimized conditions, which included a hydrolysis temperature of 30 °C, liquid–solid ratio of 5 mL/g and hydrolysis time of 10 min. The results suggest that response surface methodology can guide in optimizing the conditions of AlN hydrolysis in order to obtain the minimum fractal dimensions of residue for improving the reutilization of the dross.     

Process of aluminum dross recycling and life cycle assessment for Al-Si alloys and brown fused alumina

In 2008, around 596 000 t of aluminum dross was generated from secondary aluminum industry in China; however, it was not sufficiently recycled yet. Approximately 95% of the Al dross was land filled without innocent treatment. The purpose of this work is to investigate Al dross recycling by environmentally efficient and friendly methods. Two methods of Al dross recycling which could utilize Al dross efficiently were presented. High-quality aluminum-silicon alloys and brown fused alumina (BFA) were produced successfully by recycling Al dross. Then, life cycle assessment (LCA) was performed to evaluate environmental impact of two methods of Al dross recycling process. The results show that the two methods are reasonable and the average recovery rate of Al dross is up to 98%. As the LCA results indicate, they have some advantages such as less natural resource consumption and pollutant emissions, which efficiently relieves the burden on the environment in electrolytic aluminum and secondary aluminum industry.     

Elevated-temperature coarsening behavior in aluminum alloys

Coarsening kinetics of the equilibrium phase in the Al- rich end of the Al- Ti- Cu and Al- Ti- Ni systems have been studied using transmission electron microscopy as a function of annealing times at 698 K. The equilibrium phase in the Al- Ti- Ni system coarsens at a rate that is 6 times faster than that in the Al- Ti- Ni phase. This difference in the coarsening kinetics is related to the amount of mismatch of each of the equilibrium phases with respect to the Al- matrix.     

The behavior of aluminum in alkaline media

Polarization and impedance measurements were performed on aluminum in 0.1, l and 3 mol/l NaOH. The frequency range studied was 1×10⁻²–1×10⁴ Hz in the potential range −2 to −1 V vs. SCE. In polarization experiments the potential was extended up to 0 V vs. SCE. The behavior of the system was characterized by a high frequency capacitive loop related to the charge transfer due to dissolution of the metal, an inductive loop at medium frequency which we have attributed to surface roughening and a second capacitive loop obtained at low frequency which has been ascribed to the adjustment of the surface film to the change in potential resulting in higher charge transfer resistance.