铝灰回收加工新工艺与综合利用研究

铝熔炼过程所产生的铝灰含铝量在30％-70％之间,具有很高的利用价值,采用铝灰热回收和冷回收相结合的新工艺流程来回收铝灰中大部分的金属铝,并将低含铝量的细铝灰添加到铝电解生产中进行再生利用,成为电解槽和阳极保护环的原料,以实现废弃物的循环再利用,可充分挖掘铝灰的价值,既节能环保,也可产生良好的经济效益。     

煤气熔炼反射炉爆炸实例

用煤气熔炼反射炉熔炼铝及铝合金时,过热铝液与含硫酸根过多的烟道灰发生作用会产生恶性爆炸。文中着重分析了煤气熔炼反射炉发生爆炸的原因,叙述了爆炸的简单过程及经验教训,并提出了预防措施。     

铝灰资源综合利用

铝灰因本身含有害元素,被国家定为危险废弃物,其本身含有大量的金属铝和氧化铝,具有很高的回收价值。根据现阶段铝灰综合利用的研究进展,分析了不同工艺技术的优缺点;针对现有铝回收利用技术特点,指出冷法处理铝灰有着更多的优势;铝灰作为生产耐火材料、建筑材料和环境材料的基料,介绍了其在不同领域的应用并对铝灰的未来发展提出展望。     

降低铝熔损的炉渣处理方法

在铝合金熔炼过程中,由于铝氧化以及铝与炉壁、精炼剂相互作用而造成不可回收的金属损失叫烧损。烧损和渣中所含的金属总称为熔损。我厂采用火焰反射炉熔炼铝合金,由于炉料不同,渣量为炉料量的２％～５％,而渣中的含铝量为渣量的６０％左右。因此,正确的处理铝炉渣,回收渣中的铝来降低熔损具有重要的意义。本文结合我厂５ｔ火焰反射炉熔炼铝合金的实践,介绍处理铝炉渣来减少熔损的方法。１　减少铝炉渣的措施铝合金熔炼过程中,随着渣量增加,铝的熔损也增多,而渣量的多少与熔炼温度、炉料状态、生产工艺等因素有关。我厂从以下几方…     

废铝屑再生用熔剂及其再生工艺的研究

随着铝资源的减少,废铝再生技术越来越受重视。实验研究了熔剂配比、熔剂加入量和熔炼温度等对铸造废铝屑的回收率、合金含杂量的影响。通过正交优化和比较等方法得到了最优的熔剂配比及净化处理工艺:配方③熔剂、熔炼温度720℃、熔剂加入量4%的组合,在此条件下废铝屑的回收率为90%,合金的含杂量为0.0531%。     

铝合金液中含氢量及氧化形态的研究

讨论含锶量、熔炼温度、保温时间、炉气湿度以及氧化程度等工艺因素对铝合金液吸氢量的影响规律,并给出了铝液中的含氢量与各工艺因素之间的定量关系,同时,通过对熔液表面氧化膜形态的微观观察,解释了铝液氧化导致铝液吸氢的机理。     

铝灰综合回收利用的研究现状与进展

铝灰作为一种工业副产品,具有潜在的高价值。分析了铝灰的成分及分类,介绍了铝灰中有价值成分的回收以及铝回收设备的改进,阐述了国内外铝灰的应用,总结并展望了铝灰回收利用的发展趋势。     

废铝再生熔炼中铝渣的回收处理工艺进展

铝渣是废铝再生熔炼时不可避免的副产物,含有大量的金属铝、氧化铝、氮化铝、熔盐混合物及其他组分。对铝渣的回收处理能提高铝生产企业的经济效益并减少环境污染。综述了铝渣中金属铝的热、冷回收处理工艺以及后续铝灰中有价成分的化学法、高温法再利用技术现状,铝渣中金属铝回收工艺主要包括盐浴翻炒法、压榨法、搅拌法、离心法等热法处理工艺和破碎筛分法、电选法等冷法处理工艺;后续铝灰中有价成分再利用技术主要包括预处理工艺、化学法、高温法等再利用技术,并对国内外研究动态与发展趋势进行了分析和展望。     

废铝再生熔炼中铝渣的回收处理工艺进展

铝渣是废铝再生熔炼时不可避免的副产物,含有大量的金属铝、氧化铝、氮化铝、熔盐混合物及其他组分。对铝渣的回收处理能提高铝生产企业的经济效益并减少环境污染。综述了铝渣中金属铝的热、冷回收处理工艺以及后续铝灰中有价成分的化学法、高温法再利用技术现状,铝渣中金属铝回收工艺主要包括盐浴翻炒法、压榨法、搅拌法、离心法等热法处理工艺和破碎筛分法、电选法等冷法处理工艺;后续铝灰中有价成分再利用技术主要包括预处理工艺、化学法、高温法等再利用技术,并对国内外研究动态与发展趋势进行了分析和展望。     

铝灰综合利用现状研究与展望

铝灰是铝工业产生的一种危险固体废弃物,含有金属铝和氧化铝等成分,具有较高的回收与利用价值。铝灰的类型不同,其利用方式也不同。国内外研究显示,一次铝灰主要用于回收金属铝,二次铝灰主要用于制备聚合氯化铝和氧化铝等材料。通过总结国内外铝灰综合利用研究现状,对铝灰的研究提出建议,期待铝灰综合利用能取得进一步的发展。     

铝灰中铝资源回收工艺现状与展望

铝灰是铝工亚一种重要的副产品,其中的铝含量约占铝生产使用过程中总损失量的1%～12%.回收铝灰中的铝资源能降低成本、保护环境、节约能源和提高资源利用率,有着巨大的经济和社会效益.本文总结了铝灰的来源、分类和组成,综述了铝灰中回收金属铝的回收工艺和利用铝灰合成材料工艺,展望了铝灰回收工艺的发展前景,提出了相关建议.     

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%。     

Dross treatment in a rotary arc furnace with graphite electrodes

Aluminum baths are always covered with a layer of dross resulting from the aluminum surface oxidation. This dross represents 1–10% of the melt and may contain up to 75wt.% aluminum. Since aluminum production is highly energy intensive, dross recycling is very attractive from both energy and economic standpoints. The conventional recycling process using salt rotary furnaces is thermally inefficient and environmentally unacceptable because of the production of salt slags. Hydro-Quebec has developed a new technology using a rotary arc furnace with graphite electrodes. This process provides aluminum recovery rates of 80–90%, using a highly energy efficient, environmentally sound production method.     

Aluminum extraction from aluminum industrial wastes

Aluminum dross tailings, an industrial waste from the Egyptian Aluminum Company (Egyptalum), was used to produce two types of alums: aluminum sulfate alum (Al₂(SO₄)₃·12H₂O) and ammonium aluminum alum {(NH₄)₂SO₄AL₂ (SO₄)₃·24H₂O}. This was carried out in two processes. The first involves 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 aluminum sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purified aluminum dross tailings thus produced. This was carried out in an autoclave. The effects of temperature, time of reaction, and acid concentration on pressure leaching and extraction processes were studied in order to specify the optimum conditions to be applied in the bench scale production as well as the kinetics of leaching process.     

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.     

利用铝灰和粉煤灰铝热还原氮化制备镁铝尖晶石-刚玉-Sialon复相材料

以铝灰和粉煤灰为原料,以铝灰中的金属铝为还原剂在1550 ℃,3 h下进行原位铝热还原氮化制备镁铝尖晶石-刚玉-Sialon复合材料.采用XRD分析了不同原料配比对合成产物物相的影响,并对制备的镁铝尖晶石-刚玉-Sialon复相材料进行了显微形貌和性能表征.结果表明,当铝灰过量50%时,制备得到了镁铝尖晶石-刚玉-Sialon复合耐高温材料,其中,尖晶石为富铝尖晶石,含量为45%;刚玉含量为25%,呈板片状;Sialon的含量为26%,其Z值为4,呈柱状形貌.此时其抗折强度最大,为183 MPa,显气孔率最小,为5.3%,体积密度为2.6 g/cm~3,洛氏硬度HRB的值为123.     

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.     

Study on the Mechanical Properties of Cast 6063 Al Alloy Using a Mixture of Aluminum Dross and Green Sand as Mold

The mechanical characteristics of 6063 aluminum alloy cast in a mixture of aluminum dross and silica sand as mold have been examined. The amount of dross in the green silica sand was varied in the range of 0?C80% with bentonite as binder. In all, 40 samples were cast, and 8 of these were left in the as-cast condition for control while 32 were first homogenized at 470°C for 6?h and then rolled in a two-high mill at ambient temperature to 10% reduction in one pass. The rolled samples were solution heat treated at 515°C for 8?h followed by normalizing, annealing, and quench tempering, respectively. The samples were then simulated and tensile behavior coupled with the evaluation of microhardness and microstructures developed. The results obtained demonstrate significant improvement in mechanical properties from 50% to 80% dross in the mold. Tensile strength increased to 177?MPa and 15% elongation compared with conventional 6063-T5 aluminum alloy with 145?MPa tensile strength and 8% elongation. The improvement in mechanical properties by the quench-tempered samples can be attributed to the inducement of fine and coherent Mg₂Si crystals within the matrix. Furthermore, the overall analysis of the proportion of dross to the size of cast show that about 64% of dross generated can be utilized as mold material.     

The Nondestructive Determination of the Aluminum Content in Pressed Skulls of Aluminum Dross

During production of primary and secondary aluminum, various amounts (in some cases up to 200 kg) of aluminum dross, a mixture consisting of molten aluminum metal and different oxide compounds (the nonmetallic phase), are skimmed per tonne of molten metal. To preserve the maximum aluminum content in hot dross for further extraction, it is necessary to cool the dross immediately after skimming. One way to do this is to press the skimmed hot dross in a press. In this process, the skimmed dross is transformed into so-called pressed skulls, with characteristic geometry convenient for storage, transport, or further in-house processing. Because of its high aluminum content—usually between 30% and 70%—pressed skulls represent a valuable source of aluminum and hence are in great demand in the aluminum recycling industry. Because pressed skulls are generally valued on a free-metal recovery basis, which is influenced by the yield of recovery, or in other words, by the quality of the recycling process, it was recognized as important and useful to develop a method of fast and cost-effective nondestructive measurement of the free aluminum content in pressed skulls, independent of the technology of pressed skulls recycling. In the model developed in this work, the aluminum content in pressed skulls was expressed as a function of the pressed skulls density, the density of the nonmetallic phase, and the volume fraction of closed pores. In addition, the model demonstrated that under precisely defined conditions (i.e., skulls from the dross of the same aluminum alloy and skimmed, transported, cooled, and pressed in the same way and under the same processing conditions), when other parameters except the pressed skulls density remain constant, the aluminum content in pressed skulls can be expressed as a linear function of the pressed skulls density. Following the theoretical considerations presented in this work, a practical industrial methodology was developed for nondestructive prediction of the amount of free aluminum in pressed skulls w _Al, based on nondestructive measurement of the density ρ of the pressed skulls. The pressed skulls density is measured by a fully automatic gas displacement pyknometer with a working volume large enough to enable the insertion of the whole pressed skull sample. An additional integral part of this methodology is the set of experimentally determined linear graphs w _Al-ρ, plotted in advance for all classes of pressed skulls existing in the plant, from the experimentally collected data on pressed skulls density and aluminum recovery by melting. After selecting the proper graph w _Al-ρ, which is usually performed on an aluminum alloy basis, the pyknometric measured density of the pressed skulls can be routinely related to the aluminum content sought, within a relative error of ±5%.     

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.