高碳锰铁粉固相脱碳热力学研究

用CO2或H2O(g)作为脱碳剂进行高碳锰铁固态脱碳,当温度分别高于927℃或977℃时,高碳锰铁颗粒中外部的碳可被脱除.由于金属锰铁颗粒表面易被CO2或H2O2(g)所氧化,故脱碳反应又转变为颗粒内部的碳化锰和表面氧化锰之间的固-固相反应,使高碳锰铁继续脱碳.通过热力学计算证明了高碳锰铁用CO2或H2O(g)作为脱碳剂的可行性.     

微波加热与常规加热高碳铬铁粉固相脱碳效果的研究

研究了900~1200℃ 0~60 min微波加热和普通马弗炉加热两种方式,用固体脱碳剂碳酸钙(96.04%CaCO₃)对高碳铬铁粉(/%:55.79Cr,32.76Fe,8.16C,2.34Si)脱碳的影响。结果表明,试验条件下,微波加热高碳铬铁粉的固相脱碳效果较常规加热明显,而且常规加热时物料氧化程度严重,微波加热混合物料至1100℃ 60 min,铬铁粉脱碳率为79.04%,获得较好脱碳效果的同时,避免了物料的过分氧化。     

高碳锰铁粉与高碳铬铁粉微波升温特性对比

通过对比微波场中高碳锰铁粉和高碳铬铁粉的升温特性,分析了影响物料升温特性的因素。结果表明,微波场中高碳锰铁粉的升温效果优于高碳铬铁粉,高碳锰铁粉与高碳铬铁粉在微波场中的升温曲线均可分为2个阶段,高碳锰铁粉的平均升温速率为70.9和12.4℃·min-1,而高碳铬铁粉的平均升温速率为20.0和8.33℃·min-1;2.450GHz时,高碳铬铁粉的介电损耗较大,而高碳锰铁粉的磁损耗较大;反射损耗计算表明,高碳锰铁粉有较高的微波吸收率。     

微波加热高碳铬铁粉固相脱碳动力学

采用微波加热对高碳铬铁粉固相脱碳进行了动力学研究.以碳酸钙粉为固体脱碳剂,按高碳铬铁粉中碳与碳酸钙粉完全分解后产生的CO₂的摩尔比为1︰1和1︰1.4混合,在微波场中对内配碳酸钙高碳铬铁粉加热到不同温度并保温脱碳一定时间,测定其碳含量并计算固相脱碳反应的表观活化能.实验表明:提高内配碳酸钙的比例,物料的脱碳率会相应提高,但混合物料的微波加热升温速率会变小;对于脱碳摩尔比相同的物料,随着脱碳温度的提高和保温时间的延长,物料的脱碳率随之提高.当1200℃保温脱碳60 min时,两种脱碳摩尔比下物料脱碳效果最好,脱碳率分别为65.56%和82.96%.微波场能促进高碳铬铁粉中碳的活化扩散和CO₂的吸附扩散.微波加热内配碳酸钙高碳铬铁粉固相脱碳反应近似为一级反应,脱碳反应的表观活化能为68.43 kJ·mol^-1.     

微波加热内配碳酸钙高碳铬铁粉固相脱碳

高碳铬铁无渣脱碳法可避免有毒铬渣的排放,利用微波场可快速加热粉状物料的特性,在高碳铬铁粉中配加一定比例的碳酸钙粉,可实现高碳铬铁粉快速固相脱碳.实验结果表明：配加一定比例的碳酸钙粉,不会影响内配碳酸钙高碳铬铁粉混合物料的微波加热特性;提高混合物料的脱碳摩尔比、微波加热温度和保温时间,有利于高碳铬铁粉的深度脱碳,但相应加剧脱碳铬铁粉的氧化程度.合适的固相脱碳条件为：脱碳摩尔比1∶1.0~1∶1.4,微波加热温度1100℃,保温脱碳时间60 min.在上述条件下可使碳质量分数为8.16%的高碳铬铁粉脱碳至3.91%~1.71%,脱碳率为52.08%~79.04%.     

微波碳热法固相还原制备锰铁合金中影响因素的试验研究

在微波加热条件下对锰矿的固相还原反应情况进行了研究,分别就反应温度、配碳系数及添加剂对还原反应过程及渣金分离过程的影响进行了研究,并对各项参数进行了优化。本研究中,设计了一系列试验点,最终得到:反应温度在1400℃左右时,既有利于金属相还原,也有利于金属相凝聚,促进渣金分离,提高金属回收率;配碳系数为1.1时,向反应物中添加10%的添加剂时,有利于金属相凝聚成大颗粒,从而促进渣金分离,提高金属回收率。     

微波加热与常规加热硅锰粉固相脱硅动力学比较

采用微波加热和常规加热对硅锰粉和巴西粉锰的脱硅反应进行了动力学行为研究,以巴西粉锰为脱硅剂,与硅锰粉中的硅发生氧化还原反应.微波加热和常规加热分别加热到不同温度并保温一定时间,测定产物中硅含量并计算固相脱硅反应的表观活化能.实验表明：单一和混合料均可在微波场中快速升温.随着温度的升高和保温时间的延长,两种加热方式脱硅率均随之提高,在相同实验条件下,微波加热的脱硅率和反应速率均高于常规加热,微波加热可以提高固相脱硅率;微波加热固相脱硅反应的限制性环节为扩散环节,其表观活化能为102.93 kJ·mol^-1,常规加热脱硅反应的表观活化能为180 kJ·mol^-1,说明微波加热能改善固相脱硅的动力学条件,提高固相脱硅反应速率,降低脱硅反应的活化能.     

影响羰基铁粉电磁性能的几个因素

介绍了羰基铁粉的电磁性能及其影响因素,对实际生产有参考价值。     

高碳铬铁合金固相显微结构及破碎性能

为了研究高碳铬铁合金在浇注过程添加硅铁粉和铝后固相显微结构及破碎性能变化,在0.2 t多功能炼钢中试炉重熔某铁合金公司生产的高碳铬铁,浇注时分别添加硅铁粉和铝,分析重熔的常规高碳铬铁、添加铝及硅铁粉的高碳铬铁的固相显微结构,并将样品经颚式破碎机破碎。结果表明,高碳铬铁显微结构主要由(Cr,Fe)7C3固态相和(Cr,Fe)7Si固态相组成,有部分TiN、MnS和Al2O3夹杂物析出,常规高碳铬铁中未发现Al2O3夹杂物,而添加硅铁粉和铝的高碳铬铁中均析出了Al2O3及TiN夹杂物;添加铝的高碳铬铁组织致密,气孔率小,而常规高碳铬铁存在大量裂纹和孔洞,组织疏松,添加硅铁粉的高碳铬铁介于两者之间;经颚式破碎机破碎后,常规高碳铬铁、添加硅铁粉的高碳铬铁和添加铝的高碳铬铁破碎后粉末率分别为13.2%、11.7%和9.5%。     

Solid-Phase Decarburization of High-Carbon Ferromanganese Powders by Microwave Heating

The solid-phase decarburization of high-carbon ferromanganese powders (HCFPs) was investigated using calcium carbonate as the decarburizer by microwave heating and conventional heating methods to explore the differences of microwave heating and conventional heating. Experimental results show that HCFPs containing calcium carbonate were heated up to 900, 1000, 1100, and 1200 °C and held for 60 min for decarburization by microwave heating at decarburization ratios of 76. 69%, 82.90%, 84.11%, and 85.75%, respectively. These ratios arc higher than the decarburization ratios used for conventional heating under the same experimental conditions. The microwave heating can significantly improve decarburization ratio. This indicates the microwave heating field features a non-thermal effect, which in turn, visibly enhances the carbon diffusion ability of HCFPs. It also improves the kinetic conditions of solid-phase decarburization.     

Solid-phase Decarburization Kinetics of High-carbon Ferromanganese Powders by Microwave Heating

Solid-phase decarburization of high-carbon ferromanganese powders(HCFPs)was conducted using calcium carbonate powders(CCPs)as a decarburizer by microwave heating.Solid-phase decarburization kinetics was investigated by isothermal method.The results show that the HCFPs show excellent microwave absorption at a higher average heating rate of 80 ℃/min,while CCPs exhibit poor microwave absorption at a lower heating rate of 5-20℃/min;the heating characteristics are in-between when HCFPs and CCPs are mixed.The average heating rates of the mixture are 32.14,31.25,31.43,and 30.77 ℃/min when the mixture is heated up to 900,1 000,1 100,and 1 200℃,respectively.The good microwave absorption property of the mixed material lays the foundation for the solidphase decarburization of HCFPs containing CCPs.Solid-phase decarburization of HCFPs containing CCPs is a firstorder reaction by microwave heating.Apparent activation energy of solid-phase decarburization is 55.07kJ/mol,which is far less than that of ordinary carbon gasification reaction and that of solid-phase decarburization under the same decarburization condition by conventional heating.It indicates that microwave heating not only produces thermal effect,but also has non-thermal effect.     

Decarburization Thermodynamics of High-Carbon Ferromanganese Powders During Gas-Solid Fluidization Process

 Thermodynamic conditions of reactions between high-carbon ferromanganese powders and gas decarbonizers like O2, CO2 and water vapor were studied by thermodynamic calculation. In O2, CO2 and water vapor atmosphere, high-carbon ferromanganese powders were decarburized in a fluidized bed. When the temperature is respectively higher than 273, 1226 and 1312 K, the gas-solid decarburization reaction will occur between ferromanganese carbide on the surface of the high-carbon ferromanganese powders and different gas decarbonizers. Since metal manganese is easy to be oxidized by O2, CO2 or water vapor, the decarburization reaction will transfer into a solid-solid phase reaction of ferromanganese carbide and ferromanganese oxide, promoting external diffusion of carbon to achieve a further decarburization of high-carbon ferromanganese powders.     

Activation Energy of Nitriding Medium Carbon Ferromanganese Alloy

Investigation of some kinetics aspects of the reaction between nitrogen and medium carbon ferromanganese (MC-FeMn) was made. Nitriding process of fine medium carbon ferromanganese was carried out at temperature ranging from 973 to 1 223 K and time up to 480 min. Nitriding was carried out under nitrogen and hydrogen gas pressures. At temperature of 573 K, hydrogen gas was injected with pressure of about 0.2 MPa followed by injection of nitrogen gas up to 1.2 MPa. Sample mass was 35 g, nitrided in cylindrical chamber with 34 mm in inner diameter and 1 200 mm in length. The change in nitrogen pressure was taken as an indication for nitrogen pickup. The mass gain i.e. nitrogen pickup in kilograms per surface area (m2) was determined by time at different temperatures. Nitriding rate constants were calculated and the activation energy of nitriding process was derived from Arrhenius equation. The nitriding rate constant was found to be increased by increasing temperature of the reaction. The activation energy of nitriding process of fine medium carbon ferromanganese at time ranging up to 28 800 s is around 140 kJ/mol. It was found that the rate controlling step of the nitriding process of MC-FeMn is diffusion mechanism.     

微波加热含碳锰矿球团冶炼高碳锰铁的研究

对微波加热含碳锰矿球团冶炼高碳锰铁进行了试验研究,探明配碳系数、炉渣碱度对锰回收率的影响。结果表明,采用微波加热含碳锰矿料球,可以冶炼出符合要求的高碳锰铁合金。配碳系数及炉渣二元碱度对锰元素回收率影响显著,当配碳系数为1.4、炉渣二元碱度为2.0时,锰元素回收率最高可达90%以上。当配碳过量时,锰元素回收率下降明显。     

Microstructure of Solid Phase Reduction on Manganese Oxide Ore Fines Containing Coal by Microwave Heating

Microstructure of solid phase reduction on manganese oxide ore fines containing coal (MOOFCC) is one of important kinetics conditions of influencing microwave heating. On condition that an atomic molar ratio of rO∶rC in MOOFCC is 1∶1.06 as well as a molecular molar ratio of rSiO2∶rCaO is 1∶1.28,1 kg of MOOFCC is heated by microwave to reach 1000-1300℃ and hold different time respectively. Experiments show that the metal phase takes the iron-based metal compounds containing manganese as the main content. The manganese content of metal phase increases with the rise of temperature. The particle size of the metal phase is within the range from 0.01 to 0.05mm. MO2 phase in the stuff is entirely changed into MnO phase and the slag phase is mainly composed of wollastonite and manganese olivine. The stuff reduced is loose and massive as a whole and its porosity is from 30% to 45%. The low softening-melting property and the low density of the stuff impact,to some degree,the solid phase reduction of powder by microwave heating.     

高碳锰铁冶炼生产节能减排技术改进

为达到节能减排目的,针对云南省鹤庆锰业有限责任公司冶炼厂的特点,对电炉高碳锰铁生产的节能措施进行了探讨,针对设备选型和无熔剂生产工艺进行了实践,在提高成品率、节约能耗、无固废排放上取得了初步成果,同时简述了电炉炉衬、自焙电极等关键设备对节能的影响,对锰粉尘的回收和炉渣的综合利用作了探讨.     

低碳钢固态相变过程的原位观察

利用共焦激光扫描显微镜（CSLM）原位观察了低碳钢升温及降温过程中的固态相变,直接观测出升温时低温铁素体（α）到奥氏体（γ）以及奥氏体（γ）到高温铁素体（δ）的相变温度,和降温时δ到γ以及γ到α的相变温度。结果表明,随着升温速率从75℃／min升至130℃／min,α—γ相变开始温度从961．6℃升至1014．0℃、γ→δ相变开始温度从1351℃升至1386．9℃;降温时随着降温速率的增大（70℃／min增至530℃／min）,γ—α相变开始温度从871．6℃降至858．4℃。在升温速率为130℃／min的情况下,随着升温最大值的提高（1300℃至1480℃）,γ—α相变温度降低,相变开始温度从895．2℃降至858．4℃。     

电磁搅拌对高碳钢半固态组织的影响

 通过采用电磁搅拌制备高碳钢半固态流变浆料并进行半固态成形的方法,研究Cr5MoV、Cr12和Cr12V等高碳钢在电磁搅拌条件下的半固态组织演变过程。结果表明：电磁搅拌可以获得非枝晶的初生奥氏体。随着搅拌时间的增加,初生奥氏体的形貌变得愈来愈圆整。在较高固相分数的条件下搅拌,初生奥氏体固相颗粒有粘连现象。EBSD分析结果表明：粘连的固相颗粒呈不同的位向。这些不同位向的颗粒是从不同的晶核生长出来的,在电磁搅拌作用下相互撞击而粘附在一起。