钼精矿真空冶炼过程中主要杂质元素分布的研究

为提高钼精矿真空分解产品的质量,降低产品中Si、Ca、Mg、Al等杂质的含量,在冶炼过程中加入了碳粉。对钼精矿中主要杂质元素Si、Ca、Mg、Al在真空分解过程中的分布进行了研究。结果表明,在钼精矿中加入碳粉,有利于杂质SiO_2、Al_2O_3、MgO、CaO的去除。在研究的温度范围内,硅脱除率~100%,镁脱除率~99.7%,铝脱除率~78.44%,随着碳含量的增加及时间的延长,其脱除率可能会进一步提高。钙脱除率~9.8%。采用品位为48%的低品位钼精矿为原料,在加入碳粉真空冶炼的条件下,得到的金属钼中钼含量达到了92%,S含量降至0.69%,主要杂质SiO_2降至0.0021%,Cu0.005%,P0.005%,Mg降至0.001%,Al降至0.64%,Ca含量为0.51%。铁含量为4.44%,基本没有去除。     

RH真空冶炼过程中锰损

为了减少RH真空冶炼过程中钢水锰元素偏差和提高最终产品性能的稳定性,采用直读光谱仪对不同条件下RH真空冶炼镇静钢与非镇静钢锰损情况开展研究。结果表明,RH真空冶炼过程中锰损存在4种形式,与钢水中自由氧反应烧损、钢渣界面反应、合金粉末抽吸、真空锰挥发;随着钢水中锰含量增加、真空时间延长,钢水温度和氧化性提高,RH真空锰损逐渐增加;真空度小于1 000 Pa时,RH真空锰损随真空度的降低而降低,而当真空度大于1 000 Pa时,继续降低真空度,RH真空锰损几乎不变。通过降低RH真空度、进站锰含量和温度、减少RH真空处理时间等措施,RH结束目标锰的质量分数±0.01%命中率接近100%。     

Behavior of Element Vaporization and Composition Control of Fe-Ga Alloy during Vacuum Smelting

Saturated vapor pressure, critical evaporation temperature and evaporation loss rate of Fe-Ga alloy were calculated under different conditions of Ga and Fe contents with activity coefficients. The relationship between the change of Ga content and melting time was determined. The results demonstrated that saturated vapor pressure of Ga was higher than that of Fe under the same conditions. The difference value of critical evaporation temperature of Ga with and without Ar was nearly 800 K. The critical evaporation temperature of Fe was higher than that of Ga under vacuum, indicating that Ga was more volatile than Fe. At 1800 K, the evaporation rate of Ga was 84 times higher than that of Fe in the melt of Fe81Ga19 alloy. Under this condition, the change of Ga content and smelting time kept a linear relationship. The higher the temperature was, the faster the Ga content decreased, which was consistent with theoretical calculations.     

高温合金GH4065A的恒温静态氧化行为

研究了新型镍基高温合金GH4065A在650～750℃的静态氧化行为,基于对氧化动力学与氧化产物的分析,探讨了合金的氧化机制.结果表明:采用平均氧化增重速率指标评定GH4065A合金在650～750℃温度范围内均为完全抗氧化级别,试验条件下合金的抗氧化能力与典型涡轮盘材料FGH96、GH4720Li合金相当;合金的氧化产物主要为内层富铝的氧化物颗粒、外侧富铬的氧化物膜及表面金红石型TiO2颗粒,TiO2颗粒在氧化温度超过700℃后开始生成;合金的氧化动力学遵循抛物线型规律,受钛离子与铬离子穿过氧化膜的扩散过程共同控制.     

含锌电炉粉尘水浸处理-真空碳热还原工艺

根据国家对绿色冶金的倡导,对如何高效无污染回收含锌电炉粉尘中的金属锌及K、Na元素进行研究,采用水浸预处理回收粉尘中K、Na元素,再进行真空碳热还原回收金属锌。试验结果表明,水浸最佳方案为固液比为1∶10(g/ml)、搅拌速度为300 r/min、水浸时间为70 min。此条件下,K元素浸出率达91.09%,Na元素浸出率达85.68%。通过FactSage 8.0软件模拟真空碳热还原电炉粉尘在不同含碳条件下热力学行为,并结合前期探索试验表明,水浸渣添加质量分数为10%的焦炭、还原温度为950 ℃、保温时间为60 min的条件下进行真空碳热还原试验可有效分离Fe、Zn元素,获得金属锌锭(Zn质量分数为98.15%)及高品质铁精粉(Fe质量分数为61.93%)。     

含锌电炉粉尘水浸处理-真空碳热还原工艺

根据国家对绿色冶金的倡导,对如何高效无污染回收含锌电炉粉尘中的金属锌及K、Na元素进行研究,采用水浸预处理回收粉尘中K、Na元素,再进行真空碳热还原回收金属锌。试验结果表明,水浸最佳方案为固液比为1∶10(g/ml)、搅拌速度为300 r/min、水浸时间为70 min。此条件下,K元素浸出率达91.09%,Na元素浸出率达85.68%。通过FactSage 8.0软件模拟真空碳热还原电炉粉尘在不同含碳条件下热力学行为,并结合前期探索试验表明,水浸渣添加质量分数为10%的焦炭、还原温度为950℃、保温时间为60 min的条件下进行真空碳热还原试验可有效分离Fe、Zn元素,获得金属锌锭(Zn质量分数为98.15%)及高品质铁精粉(Fe质量分数为61.93%)。     

低铬钢水蒸气气氛下的氧化行为

为探究低铬元素钢材在水蒸气条件下的氧化行为,针对5 Cr和10Cr钢在水蒸气氛围下的氧化过程,采用热重分析仪(TGA)进行高温氧化试验.利用金相显微镜和XRD对试样氧化后的断面形貌和物相进行检验分析,研究了低铬含量钢在水蒸气氛围下表层氧化的机理.研究结果表明,由于基体表面氧化铁皮会因为水蒸气存在而产生孔洞和裂纹,成为了...     

锑砷合金除砷试验

研究了物料加入量、蒸馏温度、蒸馏时间和真空度对真空蒸馏分离锑砷合金的影响。在最佳试验条件下,一次蒸馏所得产物中含锑99.08%,含砷0.56%,锑回收率达到91.15%,基本实现了锑砷合金除砷的目标。砷以金属砷的形式产出,避免了二次污染。     

真空碳热还原-酸浸含钛高炉渣制备TiC

中国超过50％钛资源在高炉冶炼过程中进入炉渣,渣中TiO2的质量分数高达20％～30％,是一种高附加值二次资源,但在对该资源综合利用过程中,始终未能解决经济提取、硅钛难分,二次污染严重等问题.在热力学理论指导下进行真空碳热还原-酸浸联合工艺处理含钛高炉渣制备TiC研究.研究表明,碳热还原温度越高或相同温度下真空度越高越有利于炉渣中各成分还原;随着真空度增加碳热还原温度要求降低;当温度达到1 573K,真空度为1 Pa,可将SiO2还原得到具有高蒸气压的SiO、MgO被还原为Mg蒸气而离开体系,可实现渣中硅镁与钛彻底分离;真空碳热还原含钛高炉渣制备TiC的最佳条件:还原温度1673 K,炉渣粒度75μm占80％,渣碳质量比100∶38.     

真空法从粗铟中脱除镉锌铋铊铅的研究

介绍了采用真空法从粗铟中直接脱除镉、锌、铊、铅、铋取代传统试剂法脱除杂质的方法。从理论上分析了铟与上述杂质分离的可能性，并进行了温度、蒸馏时间、真空度、投料量等的条件实验和综合条件实验。结果表明，粗铟中镉、锌、铋、铊可除至高纯铟要求，铅可大部分除去。该方法是粗铟精炼中流程短、无污染、无中间渣、低能耗的新工艺、新技术。     

Dephosphorization of complexly alloyed nickel melts under vacuum induction melting conditions: I. Thermodynamics of dephosphorization

A thermodynamic computer simulation of the oxidation potential of a gas-melt-ceramic (80 wt% MgO, 20 wt % Al₂O₃) system under vacuum induction furnace conditions is used to find that the major contribution to this potential at temperatures ranging from 1673 to 2273 K is made by a nickel melt with additives of nickel protoxide. This provides the possibility of oxidative dephosphorization of the metallic melt. The computation of the saturated vapor pressure of phosphorus compounds with the IIA group elements shows that the data obtained for magnesium, calcium, and barium metaphosphates and europium orthophosphate at 1873 K indicate the principal possibility of melt dephosphorization by the evaporation of these compounds under oxidative conditions.     

高铬铸钢轧辊的组织及其氧化行为

轧辊氧化膜形成及剥落显著影响轧辊的辊耗及钢板的表面质量。为控制轧辊的氧化行为,采用增重法研究离心铸造高铬铸钢轧辊在大气及水蒸气环境中的氧化行为,并采用金相显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射(XRD)等方法研究了高铬铸钢组织及氧化膜的结构。结果表明,高铬铸钢组织为回火马氏体基体和共晶Cr7C3碳化物;氧化过程中基体优先被氧化,粗大碳化物表面几乎不被氧化;温度及环境对氧化膜生长及相结构都有一定的影响,高温及水蒸气环境加速氧化,并促进γ Fe2O3向γ Fe3O3转化。因此,控制轧辊的氧化,关键是控制轧辊的使用温度。     

粗（金属）砷真空蒸馏预提纯实验研究

针对含锑粗砷,计算了粗砷中各元素饱和蒸气压,计算结果表明：10-15 Pa、573-773 K条件下,真空蒸馏可以有效地分离粗砷中Fe、Mg、Zn、Pb、Cr、Sb等高于As沸点的金属元素以及沸点明显低于As的以Sx形式存在的S。同时,研究了一次真空蒸馏粗砷、铅-砷合金真空蒸馏粗砷工艺对粗砷中Sb、Bi、S等主要杂质元素的脱除效果。     

热轧不锈钢复合板界面氧化物夹杂的形成机制

 以不锈钢-低合金钢复合板为研究对象,利用光学显微镜及扫描电镜对复合界面附近的夹杂物进行了分析。研究发现,不锈钢复合板界面处夹杂物主要为氧化物,其成分与复合界面处的真空度有关。在较低的真空度下(真空度大于15Pa),氧化物夹杂的成分以硅为主,在较高的真空度下(真空度小于0.1Pa),夹杂的成分以铝为主。界面氧化物夹杂主要是由于高温下钢中的Al、Si和Mn等元素向复合界面处扩散并被氧化形成的。由试验结果也可知,随着真空度的降低,界面氧化也变得更加明显,当真空度的值从0.1Pa增加到20Pa左右时,界面氧化物的体积分数从15%提高到了50%。     

Fe-Ni-O体系中Fe/Ni的还原行为

取电阻炉实验和热重分析等手段,探讨了Fe-Ni-O体系中不同条件下的产物组成及Fe/Ni的还原行为.结果表明:五种样品的还原难度由低到高依次为NiO2O₃+Ni2O₃+NiO2O₄2O₃;Ni元素能够促进铁氧化物还原,其促进作用由Ni元素的初始状态决定,单质Ni>氧化物NiO>NiFe₂O₄中的Ni;NiFe₂O₄的还原过程中各产物由低温到高温依次出现的次序为Fe₃O₄、Ni、(Fe,Ni)、Fe和Fe_0.64Ni_0.36.根据实验结果,对五种氧化物体系的还原过程进行了探讨,并获得了活化能、控速环节等重要参数及相关反应机理.      

便携式能量色散X射线荧光仪测定矿渣中铟

采用电致冷Si PIN 型半导体探测器和241Am源作为激发源,以便携式能量色散X射线荧光快速分析仪为手段进行矿渣样品中铟的测定。讨论了样品中主要基体元素Fe、Cu、Pb、Zn等的影响,建立特散比法和一元回归相结合的数学模型对基体效应进行校正。仪器对自制样品重复测量20次,从测量结果分析来看,标准偏差为24.5 μg/g,相对标准偏差为64%,仪器处于正常工作状态。通过部分自制样品的测量结果与化学分析的结果对比分析,相对误差的最小值为0.35%,仪器测量结果为0.158%;相对误差最大值为26.06%,仪器测量结果为0.023%。     

Fe-2.2%Si钢在不同气氛下的高温氧化行为

为了探究硅元素、加热工艺参数(气氛、温度以及时间)对Fe-2.2%Si钢表面氧化铁皮形成过程的复合作用及影响机理,利用热重分析仪(TGA)研究了Fe-2.2%Si钢在600～1 150℃干燥空气和水蒸气条件下的高温氧化行为,利用试验得到的氧化增重数据计算出了氧化速率常数和氧化激活能,并建立了氧化动力学模型。此外,还明确了在2种气氛下氧化铁皮的生长机制与结瘤机理。试验结果表明,在2种不同氧化气氛下得到的氧化增重曲线均符合抛物线规律。当氧化气氛中含有水蒸气时,试验钢的氧化速率提高,氧化激活能降低,导致了试验钢的氧化增重增加。在2种氧化气氛下,试验钢的氧化产物均由氧化铁皮和氧化铁皮与基体界面处的富硅层组成,但在水蒸气下得到的试验钢的富硅层疏松多孔,且氧化铁皮中出现大量的孔洞以及裂纹。其氧化机制主要是氧化铁皮生长过程的生长应力以及水蒸气的存在导致生成的H₂向外扩散,造成氧化铁皮出现大量孔洞和裂纹,为氧化介质的扩散提供了通道,有利于气相物质扩散,进而促进了试验钢的氧化行为。此外,由于在氧化铁皮与基体界面形成的富硅层消耗了基体中的硅元素,导致基体表层出现贫硅区,氧化介质可以通...     

Liquid-vapor phase equilibrium in the stratifying thallium-zinc system

The pressure of the zinc vapor over liquid alloys with thallium at temperatures above the region of limited solubility in the liquid phase is determined by the method of stream and boiling points. The procedure of finding thermodynamic functions inside the stratifying region is based on the fact that chemical potentials at a constant temperature at the interface between the two-phase and homogeneous regions of the existence of liquid solutions are equal. The partial and integral thermodynamic characteristics of the vapor and condensed phases are determined and represented in the form of temperature-concentration dependences. This system is characterized by a positive deviation from the law of ideal solutions. The boundaries of the liquid-vapor phase transition of the Tl-Zn system under atmospheric pressure and under the rarefaction to 100 and 10 Pa are obtained by extrapolating the dependences of the vapor pressure of components on a high-temperature region. The region of coexistence of liquid alloys and vapor restricts a relatively small region of coexistence of liquid solutions from above, near the zinc edge of the phase diagram.     

Application of MIVM for Pb-Sn System in Vacuum Distillation

The activity coefficients of components of the Pb-Sn binary alloy system were calculated based on the molecular interaction volume model (MIVM). A significant advantage of this model lies in its ability to predict the thermodynamic properties of liquid alloys using only two binary infinite activity coefficients. Based on the MIVM, the vapor-liquid phase equilibrium of the Pb-Sn alloy system in vacuum distillation has been predicted using the activity coefficients of Pb and Sn. The results showed that the content of tin in the vapor phase was 0.008?wt?pct, while in the liquid phase, it was 83?wt?pct at 1173?K (900?°C); it reached 0.022?wt?pct in the vapor phase, while in the liquid phase, it was 92?wt?pct at 1223?K (950?°C); and it was 0.052?wt?pct in the vapor phase, while in the liquid phase, it was 97.88?wt?pct at 1273?K (1000?°C). The content of tin in the vapor phase increased with the distillation temperature increasing. Experimental investigations into the separation of Pb and Sn from the Pb-Sn alloy by vacuum distillation were carried out for the proper interpretation of the results of the model. The influence of the distillation time (20 to 80?minutes) and the distillation temperatures of 1173?K, 1223?K, and 1273?K (900?°C, 950?°C, and 1000?°C) on the separating effect was also studied. The experimental results showed that the content of tin in the vapor phase was 0.085?wt?pct, while in liquid phase, it was 83?wt?pct under the operational conditions of distillation temperature of 1173?K (900?°C), evaporation time of 20?minutes, and chamber pressure of 20?Pa; it reached 0.18?wt?pct in the vapor phase, while in the liquid phase, it was 92?wt?pct at 1223?K (950?°C), 20?minutes, and 20?Pa; and it was 0.35?wt?pct in the vapor phase, while in the liquid phase, it was 97.88?wt?pct at 1273?K (1000?°C), 20?minutes, and 20?Pa. In all these experiments, it was observed that the content of tin in the vapor phase increased as the distillation time and temperatures were increased. The experimental results are in good agreement with the predicted values of the MIVM for the Pb-Sn binary system.     

锑铅合金真空蒸馏规律的研究

对锑铅合金在真空条件下的挥发规律及锑铅合金真空蒸馏分离进行了实验研究,结果表明,真空蒸馏的压力、蒸馏温度、蒸馏时间对馏出锑的铅含量、锑的挥发率有显著影响,真空蒸馏的方法可以用来分离锑铅。