高铁赤泥煤基直接还原中铁晶粒成核及晶核长大特性

讨论了高铁赤泥煤基直接还原特性及还原过程中金属铁晶粒成核及晶核长大特征。研究结果表明，由于还原过程中生成了铁橄榄石和铁尖晶石，使得金属铁晶核更加难成；新相一旦形成后，铁橄榄石和铁尖晶石充当了成核剂，使得金属铁晶粒成核位垒降低，成核进度加快，其过程系“吸附－固相反应－自动催化”。     

还原钛铁矿中金属铁锈蚀反应速率过程的强化

以攀枝花还原钛铁矿为原料,研究在NH4Cl溶液体系下盐酸和氧气对还原钛铁矿中金属铁锈蚀反应过程及钛铁分离效果的影响.研究结果表明:添加盐酸后,还原钛铁矿中金属铁的锈蚀反应有转变为浸出反应的倾向;通入氧气后,还原钛铁矿中金属铁的锈蚀反应历程没有发生变化,锈蚀反应速度显著加快,钛铁分离效果明显改善;还原钛铁矿中金属铁的锈蚀反应过程受内扩散控制,通入氧气后锈蚀反应的表观活化能由通入空气时的13.28kJ/mol降低至8.12 kJ/mol,氧气加快内扩散过程,促进还原钛铁矿中金属铁锈蚀过程的阴极反应,从而加快金属铁的锈蚀反应速率.     

Fe－C－O三元金属熔体作用浓度计算模型

根据含化合物的金属熔体结构的共存理论，推导了Ｆｅ－Ｃ－Ｏ金属熔体作用浓度计算模型。计算的Ｎｏ′与相应的实测αｏ相符合，从而证明所得模型可以反映Ｆｅ－Ｃ－Ｏ金属熔体的结构本质。     

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.     

还原剂与脱硫剂对硫酸渣直接还原焙烧同步脱硫的影响

研究了还原剂云南煤和脱硫剂SH对硫酸渣在直接还原焙烧过程中提铁降硫效果的影响.采用X射线衍射与扫描电镜方法分析了云南煤与脱硫剂SH的作用机理.结果表明:在高温还原气氛下,硫酸渣中的黄铁矿生成具有挥发性的气态单质硫和气态羰基硫、金属铁和非磁性的陨硫铁;硫酸渣中的赤铁矿和磁铁矿则被还原为金属铁;云南煤对硫酸渣在焙烧过程中的脱硫效果比较明显,但无法达到要求的指标;添加脱硫剂SH可以进一步降低还原铁中的硫,其机理是脱硫剂与硫酸渣中的黄铁矿在直接还原焙烧过程中反应生成金属铁和没有磁性的硫化钙,通过磨矿--磁选的方法将硫化钙与金属铁分离,从而达到脱硫目标.     

浸锌渣综合利用新工艺及镓的富集行为

研究了浸锌渣还原焙烧分选综合回收有价元素新工艺,并采用电子显微镜、能谱仪和扫描电镜等分析了还原焙烧渣中金属的性质.研究结果表明当还原温度为1100 ℃、还原时间为150 min时,还原焙烧渣中铁的金属化率、镓的回收率、锌的挥发率分别为95.10%,89.10%,98.42%.还原焙烧渣经破碎、磨矿、磁选分离获得的磁性产物中含Fe 90.16%,Ga的质量浓度为2164 g/t;Fe,Ga的回收率分别为87.78%,92.42%;还原焙烧渣中金属铁是镓的主要载体矿物相,镓具有明显的亲铁特性;镓在金属铁中的富集是实现浸锌渣在还原焙烧分选过程中高效分离的基础.     

FeMo－co模拟物体系的性能表征

根据蛋白键合ＦｅＭｏ－ｃｏ的Ｋ－Ｒ模型，合成了两个ＦｅＭｏ－ｃｏ模拟物的体系，这两个体系的可见光谱和Ｍｏ／Ｆｅ／Ｓ组成都接近于天然分离的ＦｅＭｏ－ｃｏ．模拟物体系经柠檬酸盐缓冲液稀释后，再与ＵＷ４５的组份１组合，都表现出高乙炔还原活性．     

氯化物熔体中钐离子在铁电极上的电还原

利用线性扫描伏安法研究了Ｓｍ（Ⅲ）在等摩尔ＭａＣｌ－ＫＣｌ熔体中铁电极上还原的电化学行为．结果表明，Ｓｍ（Ⅲ）第一步可逆还原为Ｓｍ（Ⅱ），Ｓｉｎ（Ⅱ）进一步还原并与铁形成合金．测定了Ｓｍ（Ⅲ）在氧化物熔体中的扩散系数及扩散活化能．     

钒钛磁铁精矿直接还原过程中金属铁颗粒长大特性

通过钒钛磁铁矿精矿直接还原实验,研究了不同还原剂和添加剂对还原过程金属铁颗粒长大的影响.提高还原温度能促进还原产物中金属铁颗粒的长大,金属铁颗粒中V含量也显著增加.与用无烟煤和褐煤还原产物相比,用烟煤还原产物中金属铁颗粒明显长大,这是由烟煤中高灰分含量所引起的.金属铁颗粒长大机理的研究表明:Na2CO3和Na2SiO3的熔点较低,且能破坏铁橄榄石和铁尖晶石的结构,并生成一些低熔点物质,而SiO2能与铁橄榄石形成低共熔混合物.这些低熔点物质都有助于改善金属铁相的扩散,从而促进金属铁颗粒长大.     

煤种对钛磁铁矿直接还原-磁选钛铁分离的影响

研究了烟煤和无烟煤对海滨钛磁铁矿直接还原-磁选钛铁分离的影响机理.结果表明,在试验用量范围内,两种煤对还原铁指标的影响规律相近,煤用量低时钛磁铁矿还原不充分.随煤用量增加,被还原的金属铁越来越多,但粒度较小,与其他颗粒嵌布紧密,因此还原铁Fe品位低,Ti O2品位高,铁回收率则先提高后基本不变.所有煤用量下所得金属铁颗粒均纯净.和无烟煤相比,烟煤固定碳较低,还原气氛较弱,但灰分较高,有利于金属铁颗粒的聚集长大;因此相同用量的烟煤为还原剂时,焙烧矿中金属铁颗粒较少,但粒度较大,还原铁中Fe品位较高,铁回收率较低,Ti O2品位较低.     

Monitoring of Quality of Vermicular Cast Iron from the Front of the Furnace

Vermicular cast iron is used in certain fields because of its special physical properties. However, it is difficult to control the quality from the front of the furnace owing to the narrow range of vermiculizer and other elements that can be added to the iron. A real time method was developed to monitor the vermicular- graphite ratio of the cast iron based on fast measurements of the melt surface tension. The system includes a detector and a control unit that measure the amplitude and frequency of bubbles rising in the melt. This paper describes the methodology for measuring the surface tension of the melt and test results monitoring the vermicular-graphite ratio of the vermicular cast iron from the front of the furnace. The relationship between surface tension and graphite shape has been established. The results show that this system can quickly evaluate the vermicular-graphite ratio of the cast iron.     

承钢铁水连续脱硫装置开发与结构优化

为解决承钢铁水连续脱硫问题,开发了一套设备紧凑、操作方便的脱硫装置;基于湍流模型与多相流模型的耦合,对脱硫装置内铁水流动情况进行了计算模拟;分析研究了挡墙和喷枪位置对脱硫装置内铁水流动的影响.模拟结果表明:通过对挡墙和喷枪位置的优化,增加了铁水在包内的循环流动途径,使脱硫粉剂与铁水反应时间增长;在靠近脱硫装置出口位置设置挡墙,喷枪距挡墙1/2L时,脱硫装置内流场最好,可以实现铁水与脱硫剂的充分混合,从而提高了脱硫率,同时实现了渣铁自动分离.     

稀土在离心灰铸铁管中的作用

利用光学显微镜和扫描电镜并结合电子探针和化学分析,研究了稀土在离心灰铸铁管中的作用。结果表明,在保证灰口铸铁的先决条件下,普通离心灰铸铁管的组织,尽管可随基本化学成分和铸造条件的不同而变化,但其特征是组织粗大且很不均匀,并有明显的分层现象。加入微量稀土后,无论显微组织和宏观组织都显著趋于细化和均匀化,同时,化学成分的偏析也有明显改善。     

铁矿粉液相流动性的主要液相生成特征因素解析

烧结矿是我国高炉炼铁的主要原料,烧结矿质量将直接影响高炉冶炼及炼铁工序的经济技术指标.因此,基于铁矿粉的高温特性进行优化配矿从而改善烧结矿的产质量对于炼铁工序节能增效具有十分重要的现实意义.铁矿粉的液相流动性是非常重要的烧结高温特性指标,适宜的液相流动性可以使烧结矿获得较高的固结强度.本文模拟实际烧结黏附粉层中铁矿粉颗粒与钙质熔剂质点的接触状态,采用FastSage热力学计算和微型烧结可视化试验方法研究了固定CaO配比条件下铁矿粉的液相流动性及其主要的热力学液相生成特征影响因素.研究结果表明,采用固定CaO配比与固定碱度的熔剂配加方式下,铁矿粉的液相流动性规律明显不同.铁矿粉的液相生成量是影响其液相流动性的最主要液相生成特征因素,液相生成量越多则铁矿粉的液相流动性指数越大.铁矿粉液相流动性的配合性机制是基于其液相生成量的线性叠加原则.脉石矿物含量将在一定程度上影响铁矿粉的液相流动性,随着SiO2含量的升高铁矿粉的液相生成量减少,从而导致液相流动性指数显著降低;而Al2 O3含量增加,液相流动性指数略有升高.     

Melt Quality Evaluation of Ductile Iron by Pattern Recognition of Thermal Analysis Cooling Curves

The melt quality of ductile iron can be related to the melt's thermal analysis cooling curve. The freezing zone of the thermal analysis cooling curve was found to indicate the melt quality of the ductile iron. A comprehensive difference parameter, Ω, of the thermal analysis cooling curves was found to be related to the properties of ductile iron melts such as composition, temperature, and graphite morphology. As Ω ap- proached O, the thermal analysis cooling curves were found to come together with all the properties indicat- ing melt quality about the same. A database of thermal analysis cooling curves related to the properties of the ductile iron melts was set up as a basis for a method to accurately evaluate the melt quality of ductile iron by pattern recognition of thermal analysis cooling curves. The quality of a ductile iron melt can then be immediately determined by comparing its thermal analysis cooling curve freezing zone shape to those in the database.     

高碳变质铸铁中石墨漂浮缺陷的防止

高炉铁液经变质处理后,原生铁中粗大片状石墨成为球状或蠕团状,从而使其抗拉强度由约10kg/mm~2提高至35～63kg/mm~2,但变质高炉铁液直接用于生产遇到的首要障碍是由于生铁含碳量高(4.0～4.8％)所引起的石墨漂浮缺陷。本文从分析铸铁凝固特点出发,对高碳变质铸铁中石墨漂浮的形成机理提出了新的看法,并通过工艺试验提出了防止措施。     

高磷铁矿气基还原冶炼低磷铁

针对鄂西鲕状高磷铁矿难选、难冶的特点,从该矿矿相结构分析出发,在使用HSC计算化学软件的热力学模拟和具体实验的基础上,提出了气基还原+电炉熔分冶炼高磷铁矿的新型工艺.实验结果与HSC软件模拟结果吻合.实验室含P1.28%的高磷铁矿通过CO还原后熔分,得到含P0.27%的低磷铁;通过H2还原后熔分,得到含P0.33%的低磷铁.由熔分铁的SEM和EDS结果证实,P仍以夹杂物的形态存在,可以在熔分时通过去除铁水中夹杂物的方法进一步脱磷,以满足炼钢的要求.     

Effect of carbon species on the reduction and melting behavior of boron-bearing iron concentrate/carbon composite pellets

Iron nugget and boron-rich slag can be obtained in a short time through high-temperature reduction of boronbearing iron concentrate by carbonaceous material, both of which are agglomerated together as a carbon composite pellet. This is a novel flow sheet for the comprehensive utilization of boron-bearing iron concentrate to produce a new kind of man-made boron ore. The effect of reducing agent species (i.e., carbon species) on the reduction and melting process of the composite pellet was investigated at a laboratory scale in the present work. The results show that, the reduction rate of the composite pellet increases from bituminite, anthracite, to coke at temperatures ranging from 950 to 1300℃. Reduction temperature has an important effect on the microstructure of reduced pellets. Carbon species also affects the behavior of reduced metallic iron particles. The anthracite-bearing composite pellet melts faster than the bituminitebearing composite pellet, and the coke-bearing composite pellet cannot melt due to the high fusion point of coke ash. With anthracite as the reducing agent, the recovery rates of iron and boron are 96.5% and 95.7%, respectively. This work can help us get a further understanding of the new process mechanism.     

Spin crossover and iron-rich silicate melt in the Earth's deep mantle

A melt has greater volume than a silicate solid of the same composition. But this difference diminishes at high pressure, and the possibility that a melt sufficiently enriched in the heavy element iron might then become more dense than solids at the pressures in the interior of the Earth (and other terrestrial bodies) has long been a source of considerable speculation. The occurrence of such dense silicate melts in the Earth's lowermost mantle would carry important consequences for its physical and chemical evolution and could provide a unifying model for explaining a variety of observed features in the core-mantle boundary region. Recent theoretical calculations combined with estimates of iron partitioning between (Mg,Fe)SiO(3) perovskite and melt at shallower mantle conditions suggest that melt is more dense than solids at pressures in the Earth's deepest mantle, consistent with analysis of shockwave experiments. Here we extend measurements of iron partitioning over the entire mantle pressure range, and find a precipitous change at pressures greater than ～76?GPa, resulting in strong iron enrichment in melts. Additional X-ray emission spectroscopy measurements on (Mg(0.95)Fe(0.05))SiO(3) glass indicate a spin collapse around 70?GPa, suggesting that the observed change in iron partitioning could be explained by a spin crossover of iron (from high-spin to low-spin) in silicate melt. These results imply that (Mg,Fe)SiO(3) liquid becomes more dense than coexisting solid at ～1,800?km depth in the lower mantle. Soon after the Earth's formation, the heat dissipated by accretion and internal differentiation could have produced a dense melt layer up to ～1,000?km in thickness underneath the solid mantle. We also infer that (Mg,Fe)SiO(3) perovskite is on the liquidus at deep mantle conditions, and predict that fractional crystallization of dense magma would have evolved towards an iron-rich and silicon-poor composition, consistent with seismic inferences of structures in the core-mantle boundary region.     

熔融还原型熔体对炉衬侵蚀的研究

研究了熔融还原熔体对耐火内衬的侵蚀速度，侵蚀程度和引起内衬的微观结构变化。结果表明，内衬侵蚀的主要因素是熔体与内衬中氧化物间的化学反应，侵蚀最严重的部位是渣铁界面处及渣表面处。铁氧化物浓度越高，侵蚀速度就越高，温度越高，内衬的侵蚀速度也越快。