铁尾矿再选粗精矿深度还原含铁硅酸盐矿物的生成与还原

采用化学分析、XRD分析、SEM及EDS能谱分析方法,对齐大山铁尾矿再选粗精矿深度还原含铁硅酸盐矿物的生成与还原机理进行研究。研究结果表明:低温还原时,部分铁氧化物与脉石矿物发生固相反应,使含铁硅酸盐矿物中的铁(简称硅铁)占全铁的质量分数由未还原时的20.66%增加到720℃时的27.56%;当还原温度为770~930℃时,由于浮氏体大量生成和Na2CO3的加入,有大量低熔点富铁复杂硅酸盐矿物生成,使硅铁占全铁的质量分数由28.03%增加到53.18%;当升温到930℃时,大量钙铁辉石和少量铁橄榄石、钙铁橄榄石生成,由于Ca O的碱性氧化物效应,铁橄榄石不能大量稳定存在而转化为还原性更好的钙铁辉石、钙铁橄榄石。在高温还原条件下,钙铁辉石及钙铁橄榄石中的铁离子进入复杂硅酸盐相中,并迁移到复杂硅酸盐相表面进行还原,还原得到的金属铁沿着复杂硅酸盐相表面聚集连晶,形成金属铁环边产物层;当升温到1 300℃时,硅铁占全铁的质量分数可降至9.13%。     

顶吹搅拌液相流体的水模实验与数值模拟分析

采用水模型和VOF数学模型对浸没式气体顶吹搅拌液相流体分别进行实验与数值模拟,分析在不同喷吹条件下气泡在液相中的形变、运动及液相流体的流场特性。结果表明,随着气流量和喷管浸入液面深度的增加,气-液混合区域分布范围逐渐扩大,液面波动更剧烈;气流量越大、喷管浸入液面越深、液相温度越高,气泡运动对液相流体内部的搅拌作用越强,流体内部扰动越剧烈,液相流场域中的流场速度越大,其中,当气流量为2.0m3/h、喷管浸入液面深度为340mm时,其液相流场速度最大值达到1.18m/s。     

添加剂对钛精矿固相碳热还原强化作用的比较

利用热重分析法研究了硅铁、硼砂、碳酸钠三种不同添加剂对钛精矿固相碳热还原行为的影响.对这三种添加剂的TG,DTG,DSC曲线进行分析,结果表明硅铁会使钛精矿在还原过程中的失重率减少;而碳酸钠和硼砂会使钛精矿在还原过程中的失重率增加.三种添加剂都可以使达到最大反应速率时的温度降低.碳酸钠和硼砂可以显著提高其最大反应速率,分别提高了013%/min和018%/min;硅铁使最大反应速率降低.其强化还原机理为硅铁为反应提供一定热量,提高了反应体系的温度;硼砂促进还原过程中反应物的传输;碳酸钠可以增强碳的气化反应.     

示差分光光度法测定硅铁稀土合金中的硅

硅的测定至今多为重量法和容量法,手续冗长,且准确度较差。利用示差法进行硅的测定,已有过报导,结果较佳。但由于其实验仪器条件所限,致使该方法较难用于一般分析实验室中。本文的目的是将硅的示差分光光度测定法用于硅铁稀土合金中硅的测定,并探讨使用72型分光光度计的可能性。本文就试样溶解,铁干扰之消除以及被测有色液温度之控制等方面进行了研究。实验确认:用72型分光光度计进行硅铁稀土合金中硅的测定可以给出满意的结果。方法相对标准偏差为0.3％。 (一)仪器、药品仪器:72型分光光度计; 液池0.50cm。(按示差法要求进行挑选)     

Ti和Si对铁液黏度和凝固性质的影响

通过振荡杯高温熔体黏度仪对含Ti铁液的黏度进行测定,研究在冷却过程中Ti、Si对铁液黏度、黏流活化能、凝固温度以及凝固速度的影响.发现含Ti铁液在发生凝固以前,其黏度差别不大,黏流活化能为37.07～44.03 kJ.mol 1.Ti含量对铁液的凝固温度和凝固速度影响较大,Ti含量高的铁液开始凝固温度较高,而且凝固速度更快.硅含量低是钒钛铁液凝固温度低的主要原因.     

上海海晶硼硅铁有限公司

上海海晶硅铁有限公司是研制、生产非晶态金属材料原料—硼铁、硼硅铁的民营企业,具有雄厚的科研技术和一定的生产能力。公司通过多年的研制、开发,以多种独特的配方和先进炼方法,能生产出低杂质高品位的硼铁、硼硅铁,同时根据不同非晶态金属材料对含硼量的要求,生产出达到所要求比例的硼铁、硼硅铁。     

全实肋板耐压液舱结构的应力有限元分析

为讨论实肋板式耐压液舱结构中的应力分布和各种加强形式对液舱区结构应力的影响,利用ANSYS软件对相同尺寸的不同耐压液舱结构形式分别进行了有限元计算,通过对比得出:在船体壳板、液舱壳板加纵骨和在液舱壳板上加设中间支骨分别对降低耐压船体中的应力特别是轴向应力、液舱壳板的轴向应力以及周向应力效果十分显著.     

连铸坯截面尺寸对流动、凝固及溶质分布的影响

采用方坯连铸过程三维紊流、凝固传热及溶质传输的耦合模型,在其他模拟条件相同的情况下,研究铸坯截面尺寸对连铸过程的影响·结果表明,截面尺寸大者,入流速度大,更深浸入铸坯内部,带动较多钢液随之流动,在结晶器上部的紊流程度较高·对于FeC二元合金,由温度和溶质浓度共同决定了凝固坯壳的分布·小截面尺寸铸坯,溶质在各截面上偏析更为严重·其凝固坯壳也较薄,为防止拉漏,应采用长结晶器     

奥贝球铁的耐磨性能与机制

本文测试了不同合金元素加入量、经不同等温淬火工艺处理的奥贝球铁磨粒磨损性能，研究了其磨粒磨损机制，发现在低应力的疲劳磨粒磨损条件下，奥贝球铁以切削机制磨损，通过减少合金元素镍加入量、降低奥氏体化温度和等温淬火温度，都使得奥贝球铁的磨粒磨损性能提高。     

添加硅铁对钛精矿直接还原-渣铁分离的影响

利用碳热还原方法研究了硅铁添加对钛精矿还原及渣铁分离效果的影响.结界表明:硅铁可提高还原反应速率和铁的金属化率,在1 380℃还原30 min的金属化率达到84.5%.添加硅铁还可明显缩短还原球团冶炼周期,降低渣中金属铁含量,提高渣铁分离效率及钛渣品位(Ti O2的质量分数为84.75%).同时运用Fact Sage软件对钛渣液相线及黏度进行了理论计算,结果表明:添加硅铁对钛渣黏度影响不大,但可增大钛渣的液相区域,从而有利于金属铁的聚集长大及分离.理论计算很好地解释了实验结果.     

New insights into the effects of silicon content on the oxidation process in silicon-containing steels

Simultaneous thermal analysis (STA) was used to investigate the effects of silicon content on the oxidation kinetics of silicon- containing steels under an atmosphere and heating procedures similar to those used in industrial reheating furnaces for the production of hot-rolled strips. Our results show that when the heating temperature was greater than the melting point of Fe₂SiO₄, the oxidation rates of steels with different silicon contents were the same; the total mass gain decreased with increasing silicon content, whereas it increased with increasing oxygen content. The oxidation rates for steels with different silicon contents were constant with respect to time under isothermal conditions. In addition, the starting oxidation temperature, the intense oxidation temperature, and the finishing oxidation temperature increased with increasing silicon content; the intense oxidation temperature had no correlation with the melting of Fe₂SiO₄. Moreover, the silicon distributed in two forms: as Fe₂SiO₄ at the interface between the innermost layer of oxide scale and the iron matrix, and as particles containing silicon in grains and grain boundaries in the iron matrix.     

Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas

The carbothermal reduction of silica into silicon requires the use of temperatures well above the silicon melting point (> or =2,000 degrees C). Solid silicon has recently been generated directly from silica at much lower temperatures (< or =850 degrees C) via electrochemical reduction in molten salts. However, the silicon products of such electrochemical reduction did not retain the microscale morphology of the starting silica reactants. Here we demonstrate a low-temperature (650 degrees C) magnesiothermic reduction process for converting three-dimensional nanostructured silica micro-assemblies into microporous nanocrystalline silicon replicas. The intricate nanostructured silica microshells (frustules) of diatoms (unicellular algae) were converted into co-continuous, nanocrystalline mixtures of silicon and magnesia by reaction with magnesium gas. Selective magnesia dissolution then yielded an interconnected network of silicon nanocrystals that retained the starting three-dimensional frustule morphology. The silicon replicas possessed a high specific surface area (>500 m(2) g(-1)), and contained a significant population of micropores (< or =20 A). The silicon replicas were photoluminescent, and exhibited rapid changes in impedance upon exposure to gaseous nitric oxide (suggesting a possible application in microscale gas sensing). This process enables the syntheses of microporous nanocrystalline silicon micro-assemblies with multifarious three-dimensional shapes inherited from biological or synthetic silica templates for sensor, electronic, optical or biomedical applications.     

Constraints on the composition of the Earth's core from ab initio calculations

Knowledge of the composition of the Earth's core is important for understanding its melting point and therefore the temperature at the inner-core boundary and the temperature profile of the core and mantle. In addition, the partitioning of light elements between solid and liquid, as the outer core freezes at the inner-core boundary, is believed to drive compositional convection, which in turn generates the Earth's magnetic field. It is generally accepted that the liquid outer core and the solid inner core consist mainly of iron. The outer core, however, is also thought to contain a significant fraction of light elements, because its density--as deduced from seismological data and other measurements--is 6-10 per cent less than that estimated for pure liquid iron. Similar evidence indicates a smaller but still appreciable fraction of light elements in the inner core. The leading candidates for the light elements present in the core are sulphur, oxygen and silicon. Here we obtain a constraint on core composition derived from ab initio calculation of the chemical potentials of light elements dissolved in solid and liquid iron. We present results for the case of sulphur, which provide strong evidence against the proposal that the outer core is close to being a binary iron-sulphur mixture.     

反应烧结碳化硅材料的Na_2CO_3熔盐腐蚀行为研究

研究了在 10 0 0℃空气中的Na2 CO3 熔盐对反应烧结SiC材料的腐蚀行为 .研究结果表明 ,Na2 CO3 熔盐加速了材料的高温氧化失效 ,其腐蚀动力学过程主要包括 3个阶段 :第 1阶段是SiO2氧化膜快速溶解所造成的快速失重阶段 ;第 2阶段为材料表面液相膜形成所引起的快速氧化 (增重 )阶段 ;第 3阶段是由于熔体底部形成一层保护性SiO2 氧化膜所表现出的慢速氧化 (增重 )阶段 .因此 ,Na2 CO3 熔盐的作用使得材料表面形成大量蚀坑 .     

'Inverse' melting of a vortex lattice

Inverse melting is the process in which a crystal reversibly transforms into a liquid or amorphous phase when its temperature is decreased. Such a process is considered to be very rare, and the search for it is often hampered by the formation of non-equilibrium states or intermediate phases. Here we report the discovery of first-order inverse melting of the lattice formed by magnetic flux lines in a high-temperature superconductor. At low temperatures, disorder in the material pins the vortices, preventing the observation of their equilibrium properties and therefore the determination of whether a phase transition occurs. But by using a technique to 'dither' the vortices, we were able to equilibrate the lattice, which enabled us to obtain direct thermodynamic evidence of inverse melting of the ordered lattice into a disordered vortex phase as the temperature is decreased. The ordered lattice has larger entropy than the low-temperature disordered phase. The mechanism of the first-order phase transition changes gradually from thermally induced melting at high temperatures to a disorder-induced transition at low temperatures.     

高炉过共晶铁水的热分析定硅

应用热响应时间短的2型热分析样杯,使过共晶铁水按灰口凝固。通过准确测得共晶反应的最低、最高和结束温度等特征点,来预报其含硅量,预报精度满足实际生产中控制炉外喷粉增硅的精度要求。     

含碳球团的低温熔分

根据低nC/nO含碳球团直接还原-低温熔分工艺制备粒铁的技术思想,进行了低nC/nO含碳球团低温条件下的熔分实验研究.实验结果表明,1 300℃,nC/nO为0.8的含碳球团,还原熔分时间为55 min时,得到的铁粒中存有少量熔渣2FeO.SiO2;60 min时渣铁则完全分离,铁粒中几乎没有熔渣存在.nC/nO为0.8和0.85的含碳球团还原后渣相FeO质量分数较高,熔点较低,易于渣铁熔化分离.nC/nO为0.9的含碳球团渣相FeO的质量分数较低,熔点较高,需要较长时间或在较高温度下才能进行渣铁分离.在1 320℃,nC/nO为0.8,还原熔分时间为60 min时,铁的收得率可达86.1%以...     

Fe液中Bi蒸气溶解平衡及第三组元的影响

用密封反应室气液平衡法，测定了Ｂｉ蒸气在Ｆｅ液中的溶解平衡及第三组元Ｃｒ，Ｃｕ，Ｃ，Ａｌ和Ｓｉ对Ｂｉ溶解量的影响，得到Ｆｅ液中Ｂｉ蒸气溶解反应标准溶解吉布氏自由能与温度的关系式，以及１８７３Ｋ温度下Ｆｅ液中第三组元与Ｂｉ的活度相互作用系数。     

氯化硫酸亚铁的生产与应用

讨论了生产氯化硫酸亚铁的优点,通过与三氯化铁、聚合硫酸铁的比较试用,总结了氯化硫酸亚铁的净水效果、经济效益和使用情况。     

Behavior of fluxed lime iron oxide pellets in hot metal bath during melting and refining

Lump lime as a flux material in a basic oxygen furnace (BOF) often creates problems in operation due to its high melting point, poor dissolution property, hygroscopic nature, and fines generation tendency. To alleviate these problems, fluxed lime iron oxide pellets (FLIP) containing 30% CaO were developed in this study using waste iron oxide fines and lime. The suitable handling strengths of the pellet (crushing strength: 300 N; drop strength: 130 times) of FLIP were developed by treating with CO₂ or industrial waste gas at room temperature, while no separate binders were used. When the pellet was added into hot metal bath (carbon-containing molten iron), it was decomposed, melted, and transformed to produce low melting oxidizing slag, because it is a combination of main CaO and Fe₂O₃. This slag is suitable for facilitating P and C removal in refining. Furthermore, the pellet enhances waste utilization and use of CO₂ in waste gas. In this article, emphasis is given on studying the behavior of these pellets in hot metal bath during melting and refining along with thermodynamics and kinetics analysis. The observed behaviors of the pellet in hot metal bath confirm that it is suitable and beneficial for use in BOF and replaces lump lime.