基于熔融态氯化镁热解实现新镁钛联合的研究

现行的Kroll法生产海绵钛存在的问题是镁电解的投资较高,以及氯的环境污染控制要求较高。基于此,本工作提出了将还原蒸馏产生的熔融态氯化镁直接氧化热解得到高纯氧化镁及氯气,氧化镁经热还原法炼镁,实现海绵钛过程新的镁钛联合。本工作对新的镁钛联合关键环节熔融态氯化镁氧化热解过程进行了研究,通过绘制Mg-O-Cl体系优势区图,获得Mg O相稳定存在的条件;确定了适宜的反应条件:反应温度1200℃、输入氧分压0.1 MPa,反应时间为50 min,该条件下,氯化镁的热解率可达99.9%,产物中氯含量为0.00262%;XRD和SEM分析表明:氧化镁结晶度高,颗粒粒度分布均匀,分散性较好,为不规则的六面体,氧化镁颗粒的平均粒度在1μm左右。     

钛和钛白工业中低浓度氯气增浓途径的探讨

海绵钛生产是用金属镁还原精TiCl_4,得到海绵钛,副产品为MgCl_2.MgCl_2.电解产生金属镁,返回生产海绵钛,氯气送去氯化生产TiCl_4,镁钛联合企业称这种氯气叫循环氯气,一般比液氯的浓度低.氯化法钛白厂生产TiO_2是用精TiCl_4与O_2反应得到的,副产物氯气中还有O_2、N_2、CO_2等气体,通常称之为氧化尾气,也是要返回到氯化工序生产TiCl_4.这些浓度较低的     

国内外镁工业技术差距的剖析

本文根据国内外镁工业生产情况,分析了我国在电解法炼镁工艺中的无水氯化镁生产、氯化镁电解、粗镁精炼和镁锭表面处理过程中与国外生产技术上的差距.为提高 MgO 的氯化速度、提高氯气利用率,提出菱镁矿颗粒氯化应采用 CO 气体作为氯化 MgO 的还原剂;在氯化镁电解上应将有隔板镁电解槽改为无隔板镁电解槽或采用无隔板镁电解槽流水作业线来降低电能消耗、提高镁电流效率;在粗镁精炼上应采用光卤石与氯化钡熔剂或氟化物熔剂除去粗镁中金属杂质或非金属杂质来提高精镁品级,在镁锭表面处理上应将铬酸盐钝化法改为电化学钝化法或阳极氧化法来提高镁锭表面质量;提高镁锭表面抗蚀能力,以及金属镁应与其它有色金属形成系列合金(如 Mg—Mn,Mg—Al—Zn 和Mg—Zn—Zr 等合金)来提高镁厂的效益,在提高镁生产技术的基础上再进一步发展炼镁工业。     

增大蒸馏表面积对改善海绵钛蒸馏效率的影响研究

蒸馏工序是分离海绵钛和氯化镁的关键工序，蒸馏效率会影响产品罐中残留氯化镁以及过剩镁的去除，直接决定产品质量。另一方面蒸馏效率低会延长占炉周期，增加蒸馏电耗，影响生产效率。传统蒸馏工艺改善研究主要集中在控制蒸馏温度、延长蒸馏时间等方面，但对于提升蒸馏表面积的研究较少。通过还原前在反应器内插入钛棒增大海绵钛中部的蒸馏表面积，可在同等蒸馏物浓度和蒸馏温度的条件下达到提高海绵钛蒸馏效率的目的。研究表明，在保证氯化镁完全蒸馏的前提下，增大蒸馏表面积可明显提高海绵钛蒸馏效率，蒸馏时间由120 h降至105 h,降低蒸馏电耗，节约生产成本。     

对现有电解法炼镁工艺流程的改进意见

提出一种改进了的电解法炼镁的工艺流程,即以菱镁矿为原料,经盐酸液浸出,得到氯化镁溶液,然后喷雾造粒,这种卤粒经沸腾床在氯化氢气氛下进行脱水,制得无水氯化镁颗粒。用此颗粒作为电解生产金属镁的原料。电解产出的氯气与天然气燃烧,得到干燥的供沸腾炉脱水用的氯化氢、氮、一氧化碳的混合气体,沸腾炉的尾气经水洗涤成酸水,该酸水作为氯根循环返回前流程浸渍菱镁矿。该流程无“三废”、节能、省投资、降低原材料消耗,降低成本。并提出了实施该流程的有利条件和发展前景。     

还原液位控制对海绵钛生产的影响研究

分析研究了镁热还原四氯化钛制备海绵钛的生产过程中,还原液位控制对还原温度、还原周期、海绵钛质量的影响,并考察了两次加镁对还原液位控制与海绵钛质量影响。结果表明:还原炉1区温度随还原液位的升高而升高,还原液位偏高会引起海绵钛产品的布氏硬度与Cl、Fe含量增加;爬壁钛比例随还原液位降低而增加,平均增加约2.8%。     

一种以菱镁石和白云石混合矿物为原料的真空热还原法炼镁技术

提出一种以白云石和菱镁石的混合矿物为原料、以铝粉为还原剂的真空热还原炼镁,然后利用镁还原后的残渣制取氢氧化铝的工艺和技术,并进行实验研究。结果表明:以煅烧后的白云石和菱镁石混合矿物为原料的真空金属热还原炼镁,在还原温度为1 200℃、还原时间为2 h、铝粉过量系数为5%的条件下,镁的还原率可达89%以上,还原渣主要物相为CaO.2Al2O3,还原渣中Al2O3的含量为67%左右;该炼镁还原渣经碳酸钠和氢氧化钠的混合碱液浸出后,Al2O3的浸出率达到85%,浸出Al2O3后渣的主要成分为CaCO3;浸出液中的Al2O3以可溶解的铝酸钠存在于浸出液中,后经碳分分解制得氢氧化铝,氢氧化铝的白度达到97%。     

真空低温(250～400℃)下利用含镁冷凝物还原四氯化钛

本文较详细的论述了利用蒸馏副产物—含镁冷凝物还原四氯化钛工艺过程的操作方法、技术条件以及还原设备的结构特点。文中指出,往反应器中加入不少于装入总镁量的15％的冷凝镁,在真空低温(200℃)下可进行还原反应,化学反应热使镁锭熔化,致使温度上升到850～900℃。该法的特点在于:1)可直接利用回收蒸馏的大量副产物;2)节省电能消耗;3)提高海绵钛的质量;4)设备结构比较简单。同时,作者还对于反应过程的机理做了预测。     

热法还原镁的研究及液相Si-X体系还原镁的热力学分析

我国是金属镁生产和出口第一大国,皮江法热还原炼镁在我国金属镁生产中占据着绝对优势,但是其能耗高、污染大且效率低,成为影响镁行业持续绿色发展的限制因素.鉴于此,国内外针对皮江法进行了不断改进,并开发出新型炼镁工艺.液-液还原和固-液还原炼镁因其效率较高、周期短、能耗小等优点,成为热还原炼镁的重要发展方向.本研究基于固-液...     

硅热法生产镁的新法

滑铁卢大学研究成功了硅热法还原镁的新方法,并在美国取得了专利权。目前世界80%的镁是用氯化镁电解生产的,其余20%是通过硅热法直接还原制得的。所有被采用的方法都有不同的局限性。硅热还原时产生以下的反应:2Cao固+2MgO固+Si固——2Mg气+Ca_2SiO_4固反应是吸热反应,1100℃以上时反应速度大大提高。实际上目前所采用的反应温度,镁的蒸汽压都低于大气压。保证反应器内衬的可靠性,预热炉料和在低压     

Rapid plasma quenching for the production of ultrafine metal and ceramic powders

The rapid plasma quench concept used to produce ultrafine titanium hydride, magnesium, and aluminum powders involves the thermal dissociation of liquid reactants into gaseous components followed by rapid quenching of the products of the subject reaction to prevent back reactions. For example, in the case of titanium hydride powder production, titanium tetrachloride dissociates into titanium and chlorine atoms at 5,000 K. Expansion through a Delaval nozzle accelerates the gas to supersonic speed, cooling it very rapidly at rates as high as 7¹⁰ K/s. Injected hydrogen reacts with condensed titanium particles to form titanium hydride and with the chlorine to form hydrogen chloride. Titanium powder has been produced at 20 kg/h in a continuous reactor. Costs are projected to be lower than the Kroll process at a sufficiently large scale. Magnesium and aluminum production based upon the rapid plasma quench concept are also discussed. For more information, contact Alan Donaldson, Idaho Titanium Technologies, Inc., 101 Technology Drive, Idaho Falls, ID 83401; (208) 522-9909; fax (208) 523-6685; e-mail al@aljeanie226.myrf.net.     

Producing titanium by reducing TiCl<Subscript>2</Subscript>-MgCl<Subscript>2</Subscript> mixed salt with magnesium in the molten state

In the Kroll process for titanium sponge metal production, TiCl₄ gas is introduced and reacted with molten magnesium metal via a gas-liquid reduction reaction. The magnesium reduction reaction of the mixed salt of TiCl₂-MgCl₂ via a liquid-liquid reaction has been investigated and the results are reported in this article. First, the molten mixed salt was synthesized through chlorination reaction of solid titanium sponge placed in molten MgCl₂ salt, while TiCl₄ gas was bubbled at around 1,173K. Then, the TiCl₂-MgCl₂ was reacted with molten magnesium at similar temperatures. This proposed magnesium reduction reaction of the TiCl₂-MgCl₂ in the molten state may be more efficient, easier to control, and suitable for realizing continuous titanium production. For more information, contact Akio Fuwa, Waseda University, Department of Materials Science and Engineering, Faculty of Science and Engineering, Okubo 3-4-1, Shinjuku-ku, Tokyo, Japan 169-8555; +81-3-5286-3313; fax +81-3-5286-3488; e-mail akiofuwa@waseda.jp.     

利用固体透氧膜提取海绵钛的新技术

对克劳尔法、电解四氯化钛法等海绵钛传统生产方法以及在熔融CaCl2中直接电解还原二氧化钛制取钛的新工艺进行了总结和分析。针对这些方法中存在的不足,提出了一种利用固体透氧膜技术直接从含钛氧化物矿制备海绵钛的连续、低成本、无污染的绿色冶金新工艺。     

简析海绵钛生产镁还原工艺过程质量控制措施

还原工序是海绵钛生产关键工序之一,对海绵钛的质量有重要影响,针对原料、加料速度、还原温度、还原过程压力、反应带（液面）、设备尺寸、还原周期、镁利用率、反应器材质、蒸馏镁质量、设备密封性、检测设备等方面分析了镁还原工艺过程的海绵钛质量控制措施。     

Producing titanium powder by continuous vapor-phase reduction

One of the goals of the U.S. Department of Energy’s Albany Research Center is to reduce the cost of titanium parts by developing a continuous titanium process. In this work, titanium powder was produced by feeding liquid TiCl₄, with argon as a carrier gas, and magnesium wire into a shaft reactor at 1,000°C. The magnesium and TiCl₄ vaporized and reacted to produce a mixture of titanium, MgCl₂, and magnesium powder. Ti/Mg/MgCl₂ powder was removed from the argon gas stream by an electrostatic precipitator, and the titanium powder was separated from the magnesium and MgCl₂ by either vacuum distillation or leaching. Vacuum distillation produced sintered titanium powder with lower oxygen levels, but unacceptably high levels of magnesium and chlorine. Leached powder was spherical and free-flowing with low levels of magnesium and chlorine, but the oxygen content was no lower than 0.82%. The high oxygen content of the leached powder is caused by surface oxidation of the submicrometer titanium powder. For more information, contact S.J. Gerdemann, Albany Research Center-Department of Energy, 1450 Queen Avenue S.W., Albany, Oregon 97321-2198; (541) 967-5964; fax (541) 967-5868; e-mail gerdeman@alrc.doe.gov.     

Iron removal and recovery in the titanium dioxide feedstock and pigment industries

Titanium and iron are closely related in nature. Therefore, for both environmental and economic reasons, the fate of iron may be very crucial for the titanium extraction industry. Smelting of ilmenite to produce titania slag allows for the recovery of iron as high purity pig iron. However, in the production of synthetic rutile from ilmenite sands, iron is returned to the mine site as a fine oxide/hydroxide residue. Some projects to recover iron from these residues never reached the industrial scale. In the titanium dioxide (TiO₂) pigment industry, iron is deported as sulfate or chloride salt, which is usually neutralized and rejected at a considerable cost. In the past few years, ferrous sulfate heptahydrate (or copperas) and iron chloride have found a few applications, but still the demand for these iron salts is not enough to cover the production volumes. The review of some new processes currently under development clearly shows that iron recovery is essential for the long-term viability of any new ilmenite upgrading or TiO₂ pigment production process.     

熔盐电解法生产海绵钛的回顾和新技术开发

回顾了熔盐电解法生产海绵钛的研究 ,介绍了熔盐电解TiCl4生产海绵钛的工艺过程 ,重点提出一项在熔融CaCl2 中直接电解还原TiO2 生产海绵钛的新工艺。     

Ion beam analysis of corrosion films on a high magnesium alloy (Magnox Al 80)

Specific nuclear resonance reactions, ⁴He ion backscattering and ESCA have been used to investigate the depth distribution of oxygen, carbon, fluorine and magnesium in complex corrosion films formed on Magnox AL 80 after exposure to nuclear reactor coolant gas and to multi-component aqueous solutions.Results of experiments with water enriched in H₂¹⁸O have shown that magnesium hydroxide which is highly permeable to solution is formed at the metal/film interface. The oxide formed in hot CO₂ contains carbon, carbonate and traces of carbide-like material. This oxide hydrates uniformly in solutions of pH ? 11.5 but complete equilibration with solution is rather slow.In solutions containing fluoride ions which inhibit the corrosion reaction the product is a hydroxy-fluoride Mg(OH)_2?x and fluoride also exchanges to an appreciable extent with pre-formed magnesium hydroxide.     

海绵钛生产中多点加料工艺的探索与实践

在海绵钛的生产实践中，随着反应器逐渐向大型化发展，传统的单点加料工艺存在着一定的不足。而在大型反应器中采用多点加料工艺，可以降低还原反应温度，缩短还原周期，消除夹心氯化镁的存在，为提高海绵钛的产量和质量，提供了一条切实可行的生产途径。     

Synthesis of TiO<Subscript>2</Subscript> Nanoparticles from Ilmenite Through the Mechanism of Vapor-Phase Reaction Process by Thermal Plasma Technology

Synthesis of nanoparticles of TiO₂ was carried out by non-transferred arc thermal plasma reactor using ilmenite as the precursor material. The powder ilmenite was vaporized at high temperature in plasma flame and converted to a gaseous state of ions in the metastable phase. On cooling, chamber condensation process takes place on recombination of ions for the formation of nanoparticles. The top-to-bottom approach induces the disintegration of complex ilmenite phases into simpler compounds of iron oxide and titanium dioxide phases. The vapor-phase reaction mechanism was carried out in thermal plasma zone for the synthesis of nanoparticles from ilmenite compound in a plasma reactor. The easy separation of iron particles from TiO₂ was taken place in the plasma chamber with deposition of light TiO₂ particles at the top of the cooling chamber and iron particles at the bottom. The dissociation and combination process of mechanism and synthesis are studied briefly in this article. The product TiO₂ nanoparticle shows the purity with a major phase of rutile content. TiO₂ nanoparticles produced in vapor-phase reaction process shows more photo-induced capacity.