Extraction of vanadium from molten vanadium bearing slag by oxidation with pure oxygen in the presence of CaO

A novel process of vanadium extraction from vanadium slag in its molten state was conducted at the laboratory scale by oxidation with pure oxygen in the presence of CaO. The effect of mass ratio of CaO to V2O5 on the recovery of vanadium was studied. The sintered samples were leached by H2SO4 solution and characterized by XRD, XPS, SEM and EDS techniques. Compared with the roasting process, the energy saving effect of the proposed process was also discussed. The results showed that vanadium-rich phases were formed and vanadium mainly existed in the forms of CaV2O5 and Ca2V2O7. The formation mechanism of calcium vanadates in the molten vanadium bearing slag was explained. The XRD and XPS results implied that there was a limit to the oxidation reaction of V(IV) to V(V) under the high temperatures even though oxygen-supply was sufficient. An increase in the CaO content led to an increase in the formation of Ca2V2O7. About 90%of the vanadium recovery was obtained under optimal experiment conditions (mass ratio of CaO to V2O5 of 0.6, particle size 120 to 150μm, leaching temperature 90 °C, leaching time 2 h, H2SO4 concentration 20%, liquid to solid ratio 5:1 mL/g, stirring speed 500 r/min). The energy of 1.85×106 kJ could be saved in every 1000 kg of vanadium bearing slag using the proposed process from the theoretical calculation results. Recovery of vanadium from the molten vanadium bearing slag and utilisation of its heat energy are important not only for saving metal resources, but also for energy saving and emission reduction.

Effect of slag on oxide inclusions in carburized bearing steel during industrial electroslag remelting

Industrial experiments with three types of slags were performed to investigate the effect of slag on oxide inclusions during electroslag remelting(ESR) process. G20CrNi2Mo bearing steel was used as the consumable electrode and remelted using a 2400-kg industrial furnace. The results showed that most inclusions in the electrode were low-melting-point CaO-MgO-Al_2O_3. After ESR, all the inclusions in ingots were located outside the liquid region. When the slag consisted of 65.70 wt% CaF_2, 28.58 wt% Al_2O_3, and 4.42 wt% CaO was used, pure Al_2O_3 were the dominant inclusions in ingot, some of which presented a clear trend of agglomeration. When the ingot was remelted by a multi-component slag with 16.83 wt% CaO, a certain amount of sphere CaAl_4O_7 inclusions larger than 5 μm were generated in ingot. The slag with 8.18 wt% CaO exhibited greater capacity to control the inclusion characteristics. Thermodynamic calculations indicated that the total Ca and Mg in ingots were attributed from the relics in electrode and strongly influenced by the slag composition. The formation of ingot inclusions was calculated by FactSage^(TM) 7.0, and the results were basically in accordance with the observed inclusions, indicating that a quasi-thermodynamic equilibrium could be obtained in the metal pool.

Effect of oxidization on enrichment behavior of TiO_2 in titanium-bearing slag

Due to the dispersed distribution of the titanium component in various mineral phases and very fine grain size, it is difficult to recover the titanium component from the slag. In order to utilize titanium resources, selective enriching and selective growing of the titanium component from the molten slag is expected. In this paper, the selection of the best titanium enrichment phase and the effect of oxidization on the enrichment of titanium by blowing air into the molten slag were studied. The results showed that through oxidizing the slag, the content of the perovskite phase increases while that of the other titanium-bearing mineral phases decreases until they disappear. Most titania resources were enriched into the perovskite phase and increase in size. The process of enrichment and growth is easily carried out.

Selective enrichment of TiO_2 and precipitation behavior of perovskite phase in titania bearing slag

The effects of additive agents and growth behavior of perovskite phase as well as temperature change of slag at semi industry scale test were studied. The results show that the increase of steel slag does good to titania enrichment, however, it isn’t useful for the growth and coarsening of the perovskite phase. The additive Si-Fe powder can promote titania enrichment and make perovskite phase grow up easily. While air is blown into the molten slag, the reduced components in slag are oxidized and the released heat raises the temperature of slag.

Effects of the continuous cooling process conditions on the crystallization and liberation characteristics of anosovite in Ti-bearing titanomagnetite smelting slag

This study involved the investigation of the effects of the continuous cooling process conditions on the crystallization and liberation characteristics of anosovite in Ti-bearing titanomagnetite smelting slag. The samples were heated until melting and then the temperature was held at 1650℃ for nearly 0.5 h;subsequently, the samples were cooled at different cooling rates to different temperatures and water-quenched after being held for different times at these temperatures. Last, the obtained crystallized samples were used to analyze the crystallization and liberation characteristics. It was found that, during the continuous cooling process, anosovite particles were found to initially precipitate in the slag at a relatively high crystallization temperature, showing the characteristics of euhedral crystal. The precipitation and growth of anosovite grain is strong and the morphology of anosovite was basically not affected by the continuous cooling conditions. From the morphology perspective, the formed anosovite is an excellent Ti-rich phase to be selective separated. The formation of spinel and diopside is negative for the liberation and selective separation of the anosovite phase. The crystallization diagrams of TiO2-MgO-CaO-SiO2-Al2O3-FeO slag undergoing different continuous cooling processes were constructed to help to determine the optimal continuous cooling–quenching condition for selective separation of anosovite. Moreover, the addition of B2O3 can enlarge the range of the optimal continuous cooling–quenching conditions for selective separation of anosovite.

Isothermal precipitation and growth process of perovskite phase in oxidized titanium bearing slag

The isothermal precipitating behavior of perovskite phase in oxidized titanium bearing slag was studied by quenching method.The kinetics of precipitating process and crystal growth of perovskite phase was analyzed.The results show that the precipitating and growth of perovskite are non-equilibrium process at the beginning of isothermal treatment.There are two factors influencing the growth rate of perovskite phase on non-equilibrium condition,one is the supersaturation concentration of perovskite and the other is the coarsening arising from the growth of larger perovskite at the expense of smaller ones.The precipitation kinetics of perovskite phase can be nearly described by the JMAK equation.

Numerical simulation of the temperature field of titania-bearing BF slag heated in a microwave oven

Considering the characteristic of selective heating of microwave and the treatment of titania-bearing BF slag, a mathematical model for the heating of a slag specimen is developed. The temperature distribution in the specimen is studied by numerical simulation. The temperature in the center of the cylindrical slag specimen is the highest and the temperature decreases when the radius increases rapidly. In this case, the temperature rising rate decreases with heating time rapidly, and it tends to zero when the heating time is up to 150 s.

Antibacterial Properties of V-doped Titanium-bearing Blast Furnace Slag Prepared at Different Calcination Temperatures

Perovskite-type V-doped titanium-bearing blast furnace slag (VTBBFS) photocatalyst was prepared by high-temperature solid phase method.The influence of calcination temperature on the photocatalytic and antibacterial properties of VTBBFS was studied in details.Its composition and microstructure were evaluated by X-ray diffractometer,ultraviolet-visible absorption spectrometer,Fourier transform infrared spectrometer and scanning electron microscope.The antibacterial properties of VTBBFS to Candida albicans were investigated by flask oscillation method.The results showed that the optical absorption and antibacterial properties of VTBBFS were the best with 10%(ω) doping of vanadium,prepared at 800℃ for 2 h,and its sterilization rate was close to 100% to Candida albicans (ATCC10231).The minimum inhibitory and minimum bactericidal concentrations were 25 and 50 mg/mL.When the concentration was 0.2 μg/mL,the catalyst had the least toxic toxicity.

Slag Resistance of Magnesite-chrome Brick Impregnated with Chrome-bearing Sols

Cr2O3 has eminent slag corrosion resistance. So, the magnesite -chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world. After chromebearing sols being prepared by sol-gel method, single sol （ Cr（ OH）3） and mixed sol （ Mg（ OH）2 - Cr（ OH）3） were impregnated into magnesite - chrome bricks by vacuum impregnation. The corrosion resistance of the impregnated bricks to silicon steel slag was studied by porosimetric analysis and fractal dimension calculation. The results showed that the corrosion resistance of impregnated magnesite -chrome brick was better than that of the unimpregnated brick and the brick impregnated by MgSO4 solution, and the one which has surface-treated by Mg（ OH）2 -Cr（OH）3 sol was the best, mainly because of lower apparent porosity, smaller pores diameter and their smoother inner sarface.

Kinetics of non-isothermal precipitation process of perovskite phase in oxidized Ti-bearing blast furnace slag

Kinetics of non-isothermal precipitation process and crystal growth of perovskite phase in oxidized Ti-bearing slag were investigated. The oxidized slag was obtained by blowing the air into the molten Ti-bearing blast furnace slag through a lance. The experimental results show that the cooling rate has important effect on precipitation and growth of perovskite phase in oxidized slag;the lower cooling rate is in favor of not only the increase of the volume fraction of perovskite phase,but also the growth of perovskite phase grain sizes. The particle coarsening in non-isothermal process has important effect on the crystal growth of perovskite phase. The relative volume fraction of perovskite phase could be approximately described by JMAK equation,and the experiential expression of the average crystal radius of perovskite phase was also obtained.

Experimental Crystallization of Synthetic V-bearing Steelmaking Slag with Al_2O_3 Doped

The phenomenon of crystallization was implemented in the synthetic V-bearing steelwork slag based on the composition of factory slag from the Masteel Co., and the possibility of undercooling as a technique to precipitate V-concentration phase was demonstrated. The effect of 20wt% Al_2O_3 additive introduced into the slag on intensifing the precipitation was also investigated. X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) were used to investigate the slag after heat treatment. It is demonstrated that gehlenite and grossite are the major crystalline phases. Whitlockite with a high content of V_2O_5 (called V-concentration phase hereafter) nucleates homogeneously and hetergeneously and grows with decreasing undercooling. At 1548 K, the crystals of V-concentration phase grow up as the duration of time, with a medium grain size of 25 μm at 300 min holding time.

Electrorheological effect of Ti-bearing blast furnace slag with different TiC contents at 1500°C

The electrorheological properties of CaO–SiO2–Al2O3–MgO–TiO2–Ti C slags were investigated to enhance understanding of the effect of TiC addition on the viscosity, yield stress, and fluid pattern of Ti-bearing slags in a direct-current electric field. The viscosities and shear stresses of 4wt% and 8wt% Ti C slags were found to increase substantially with increasing electric field intensity, whereas virtually no rheological changes were observed in the 0wt% TiC slag. The Herschel–Bulkley model was applied to demonstrate that the fluid pattern of the 4wt% TiC slag was converted from that of a Newtonian fluid to that of a Bingham fluid in response to the applied electric field; and the static yield stress increased linearly with the square of the electric field intensity.

Beneficiation of Titanium Oxides From Ilmenite by Self-Reduction of Coal Bearing Pellets

The study on the beneficiation of titanium oxides from Panzhihua ilmenites by reduction of coal bearing pellets was carried out. The iron oxides in pellets were efficiently reduced to metal iron, and titanium oxide slag beneficiated was separated from metal iron. The effect of temperature, flux and coal blending ratio on the reduction and separation was investigated, and rational parameters were determined. A new process for the beneficiation of titanium oxides by rotary hearth furnace （RHF） was proposed.

Modification of Inclusions in ESR Bearing Steel

Electroslag remelting (ESR) process using consumable electrode deoxidized with Ca-Si and Fe-Si instead of Al, and acid slag (CaF_2SiO_2Al_2O_3CaO) instead of universal slag ANF_6(CaF_2. 70 %+A1_2O_3.30 %) could change brittle inclusion (alumina) to ductile inclusion (silicate) in remelted steel. Fatigue life of bearing steel could be increased significantly in this way.

Recovery of Titanium from the Rich Titanium Slag by H2SO4 Method

The blast furnace slag bearing Ti02 in Panzhihua, China, is an important resource to be utilized. In the present paper, the effects of the ratio of slag to H2S04, the reaction temperature, the particle size of the slag, and the concentration of H2S04 on the reaction rate and the acidolysis ratio of Ti were studied. The results indicated that the maximum acidolysis ratio reached 98%, which can serve as an experimental basis for the production of titania from the slag.

Valorization of Metallurgical Waste in Technical Road： Case of Blast Furnace Slags

The main objective of this paper is to study the mechanical properties of a material formulated in the laboratory which is a GS （gravel slag） based on crushed aggregates treated with metallurgical waste which is the blast furnace slag. The authors show in particular, as a road application, the treatment of gravel slag provides mechanical properties allowing its use in road construction. We will introduce different contents of slag （10%, 15%, 20%, 25% and 30%） and test the mechanical properties of the mixtures obtained through CBR Punching tests, simple compression test and tensile test. This work is in the context of the valorization of blast furnace slag, which is found in large quantities as waste dumps that came to disturb the environment.

Basicity for blast furnace-type slag containing B_2O_3 and high MgO

There is quite abundant resource of ludwigite ore in Liaoning Province of China. Content of MgO in the slag of pyrometallurgical separation of boron from iron is much higher than that in the ordinary slags. Through the equilibrium partition ratio of sulfur L S between the metal and the slag in an atmosphere of CO N 2, the acidic coefficients for B 2O 3 and the basic coefficients for MgO were estimated. The basic formulae were given for the blast furnace type slag containing B 2O 3 and high MgO.

钛渣熔体结构及传输性质分子动力学模拟研究进展

高品位钛渣(TiO_(2)含量≥90%)的高效制备不仅是高品质钛产品生产的关键,而且已成为我国钛冶金行业发展的迫切需要。钛铁矿还原熔炼过程钛渣熔体传输性质的调控是实现高品位钛渣高效制备的关键。国内外学者采用分子动力学模拟的方法,开展钛渣熔体结构演变及传输性质的研究,取得了显著的进展,证实了分子动力学模拟的方法在钛渣熔体研究中的有效性。分子动力学模拟的方法在研究钛渣熔体结构和性质方面具有显著的优势,不但能考察钛渣熔体结构参数、传输性质及相关微观细节,而且不受试验条件(高温、高腐蚀性、高化学活性)的限制。通过分子动力学模拟能够获取钛渣熔体丰富的结构信息和重要的传输性质,避免了钛渣熔体结构及物理性质试验测试中存在的难题。最后,结合冶金熔体成分和结构的复杂性,总结存在的问题,对分子动力学模拟在熔体结构及传输性质研究中的应用进行了展望。

含钛高炉渣氯化铵焙烧活化试验

针对钒钛磁铁矿高炉冶炼副产的含钛高炉渣成分复杂、难以处理特点,采用氯化铵焙烧活化—浸出提质处理工艺进行钙铝镁等杂质金属元素的脱除,获得钛富集物。考察焙烧和浸出过程中各参数对杂质脱除的影响。结果表明,在焙烧温度450℃、焙烧时间1 h、氯化铵配比40%、原料-0.074 mm占比83%,盐酸浓度9%、液固比5、浸出时间4 h、浸出温度90℃的优化条件下,含钛高炉渣中钙、铝、镁脱除率分别达到73.22%、90.04%、91.39%,钛损失率仅有0.34%,达到选择性脱除炉渣中杂质元素,提高含钛高炉渣品质的目的。

空气和钛精矿对含钛混合熔渣钙钛矿富集行为的影响

采用XRD、SEM、EDS、Image-J等分析手段,探讨空气和钛精矿对含钛熔渣中钛资源富集行为的影响。通过对含钛混合熔渣改性,熔渣中钙钛矿晶体形状发生变化,降低钙钛矿晶体运动阻力,方便上部钙钛矿晶体向下部迁移和富集,得到高品位人造钙钛矿精矿。结果表明:合适的氧化时间有利于熔渣中的低价钛向高价钛转化,适量的添加钛精矿有利于促进钙钛矿晶体的成核,以球形晶体析出。因此,在较佳氧化时间2 min和较佳钛精矿添加量12%共同作用下,Ti组分以球形钙钛矿晶体富集于改性渣底部,钙钛矿体积分数由25.12%增加到61.50%。