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By Linfeng Zhou, Rong Sun, Guanghui Li, Zhiwei Peng, Tao Jiang

The effects of microwave roasting on separation of rhenium (Re) and molybdenum (Mo) from a molybdenite concentrate have been investigated based on evaluation of the heating characteristics of the concentrate in the microwave field. The results show that a variety of operating variables, namely microwave power, sample weight, sample geometry, roasting temperature, roasting time and atmosphere significantly impact on the volatilization rates of Re and Mo. The optimum conditions for Re-Mo separation are microwave power 1300 W, sample weight 20 g, sample geometry pellets, temperature 600 oC, time 1.5 h, and atmosphere 20%O2. Under these experimental conditions, the volatilization rate of Re reaches 88.12%, while that of Mo is just 5.15%. Microwave-assisted roasting provides an alternative route to separating Re and Mo from molybdenite concentrate.

Jan 1, 2016

By Pengcheng Li, Wei-Tong Du, Yu Wang, Gang Wen

Carbon dioxide could be utilized as a weak oxidant and a kind of coolant to oxidize elements, meanwhile, helping control the temperature during the converter vanadium extraction process. However, the optimum content of CO2 and the cooling effect of CO2 at low content have not been reported. In this study, experimental research based on the influence of different CO2 contents from 0% to 25% injected to the vanadium-containing hot metal was carried out, as well as contrast experiments of O2-N2 mixed blowing. The results indicated that the optimum content of CO2 was 15%. Under the optimum condition, the oxidation of [C] was the lowest and the oxidation rate of [V] was 96.9%, while the temperature was also lower than the O2-N2 mixed blowing. This paper provide a potential property for utilizing CO2 during the converter vanadium extraction process.

Jan 1, 2016

By Jintao Gao, Zhancheng Guo, Chong Li

A new approach to enrich MFe and RO phase from the converter slag by super gravity was investigated. The samples obtained by the gravity coefficient G=600 and cooling rate V=5K/min from 1623K to 1373K appeared significant stratification and the MFe gathered at the bottom of sample. With the help of metallographic microscopy and X-ray diffraction, it is found that large quantity of white RO phase gathered at the lower part of the sample as the concentrate, with volume fraction appearing gradient distribution along the direction of super gravity, while the upper part was mainly composed of dicalcium silicate as the tailing. The mass fractions of the FeO, MgO and MnO in the concentrate are up to 40.46%, 6.9% and 3.91%, while that in the tailing are just 11.65%, 2.15% and 1.55%. The recovery ratios of FeO, MgO and MnO in the concentrate are 60.35%, 58.45% and 72.24%, respectively.

Jan 1, 2016

By Liangju He, Peixuan Ouyang, Peijie Li

Single-pulse laser ablation of aluminum and titanium alloys under glass confinement is investigated. Processing parameters such as laser intensity and gap width between targets and glass are varied. Surface morphologies and crater profiles of the alloys after laser ablation are studied by SEM and white-light interferometric microscope, respectively. The effects of gap width and laser intensity on surface morphologies and crater profiles of targets are systematically analyzed. In addition, the generation of porous surface structures in Ti target is regarded as the result of phase explosion in the molten surface layer of targets and the thermodynamic condition in our experiment for phase explosion is evaluated.

Jan 1, 2016

By Guangliang Wu, Dongchang Huang, Xinbin Liu

Oxidation Kinetics of SPHC was analyzed by TGA, and the curve of oxidation weight gain with different temperature was acquired. It is found that, when the oxidation temperature is between 500 and 600 , all the curves are linear; when the oxidation temperature is above 700 , the curves are close to parabolic. At the temperature of 900 , the oxidation weight gain increases dramatically. The TGA results indicate that the activation energy of SPHC steel is 146.19 kJ/mol at the temperature of 500 900 , and an oxidation kinetic model was set up for variable temperature. Based on the temperature change during rolling process, numerical simulation of oxide scales evolution was carried out for SPHC steel, and the simulation result agreed well with measured ones. It can provide a basis for estimating the scale growth and controlling the temperature on site.

Jan 1, 2016

By Hans Jürgen Maier, Gregory Gerstein, Florian Nürnberger

Microstructural analysis to support the development of material models provides valuable information to design complex forming operations. Damage models such as e.g. by Gurson consider spherical voids only. However, investigations of bcc steels by scanning electron microscopy reveal that voids exhibit an ellipsoidal shape with progressing deformation. The material’s weakening in the Gurson model is taken into account by the void volume fraction. Therefore, a three-dimensional characterization of the void shape offers important data for modelling. Thus, information on the anisotropy of the process of void evolution and accordingly, about the anisotropy of the deformation process is provided. Application of the information regarding the void shape anisotropy within the Gurson model is discussed.

Jan 1, 2016

By Jiang Diao, Yong Qiao, Xuan Liu, Tao Zhang, Bing Xie

Adding CaO into the vanadium extraction converter is an effective way to decrease the dephosphorization burden in subsequent steelmaking process. The crystallisation process of spinel is one of the most decisive factors in the subsequent extraction. The theoretical calculation results show that the temperature of the peak total crystallization rate will decrease 5K with basicity increasing 0.1. The relation between cooling conditions and grain size of spinels is also discussed. It is found that low cooling rate and high basicity benefit spinel crystal growth. And the non-isothermal crystallization kinetics results indicated that the restriction factors of spinel growth is that solid crystals accept new components from liquid-solid interfacial. While the sample was cooled down to 1250 (1523K) at cooling rate of 5K/min, the crystal growth is consistent with Ostwald coarsening grew up law, and controlled by diffusion of particle.

Jan 1, 2016

By Fuqiang Zheng, Feng Chen, Wenting Duan, Yufeng Guo, Tao Jiang

High-quality titanium-rich material is of significance in the development of titanium industry as it is the main raw material to produce sponge titanium and titanium white using chloride process. Activation roasting of titanium slag with high Ca and Mg contents as adding H3PO4 followed by acid leaching was investigated to prepare titanium-rich material. The effects of H3PO4 dosage, roasting temperature and time, hydrochloric acid quantity, acid leaching temperature and time on TiO2 grade and removal of impurities were studied. The results show that after the finely ground titanium slag roasted with 8% H3PO4 at 1000 for 2h, most Mg impurities in anosovite solid solution structure were converted into simple acid–soluble compounds. The impurities such as Ca and Mg obviously decreased when the hydrochloric acid concentration was 20%, leaching at 100 °C for 2h, from which a titanium-rich material containing 82.56% TiO2 and 1.15% (CaO+MgO) was obtained.

Jan 1, 2016

By Zhigang Zak Fang, Michael L. Free, Jaehun Cho, Syamantak Roy, Amarchand Sathyapalan

Leaching characteristics of impurity removal from the Upgraded Titania Slag (UGS) using hydrochloric and boric acids has been investigated. Specifically, this study has focused on removal of iron oxides from the UGS that has been reduced by hydrogen gas and magnesium at 750oC for 5 hours. Reduced UGS is mainly composed of titanium hydride and impurities like iron oxides, silicon oxide, aluminum oxide, and magnesium oxide. The concentration of hydrochloric and boric acids and the leaching temperature have been chosen as the prime variables to identify the optimum conditions and leaching characteristics for removal of iron oxides. It was observed that under the constraint that 1 wt % of titanium hydride loss is the maximum amount tolerable, 0.1M HCl with 1M boric acid and 90oC are the most effective parameters for iron removal from the reduced UGS. Also, the overall rate of reaction seems to follow interfacial reaction controlled kinetics. The calculated activation energy of the reaction is 73.90kJ/mol.

Jan 1, 2016

By Yuanbo Zhang, Huanpeng Mi, Guanghui Li, Binjun Liang, Zhiwei Peng, Tao Jiang

Ludwigite ore has not yet been utilized on an industrial scale due to its complex mineralogy and fine mineral dissemination. In this study, sodium salts were employed to enhance the separation of iron and boron by reductive roasting-magnetic separation. It was found that the separation of iron and boron as well as the iron grade and recovery were significantly improved b y the addition of Na2SO4 or Na2CO3. Under the reduction temperature of 1050 °C, reduction time of 60 min and magnetic intensity of 0.1T. Compared with the inexistence of sodium salts, the iron grade and recovery of the magnetic concentrate increased from 83.3% and 88.6% to 93.2% and 95.1%, respectively, by adding 6% Na2CO3. The XRD and microstructure analyses indicated that the iron oxides were transformed into metallic iron and the average metallic iron grains were grown to over 40μm which was beneficial for separation of metallic iron from gangue.

Jan 1, 2016

By Katia Vutova, Vania Vassileva

Investigations and results on the refining of tungsten scrap applying electron beam melting (EBM) in vacuum are presented and discussed. In this work EB melting experiments were performed in single or double-melt operations with different power inputs and refining times for tungsten purification and recovery of multiple metals (including refractory and other metals such as Mo, Nb, Cu, Zn, etc.), which are alloyed elements or impurities with high concentrations in the initial materials. Evaluations for extraction of some valuable metals, generated in the condensate at their removal from the liquid metal during the refining process are provided. Efficient technological regimes for e-beam melting and refining that enable the simultaneous production of pure metal ingots and condensates that can be used directly or can be used for subsequent extraction of expensive and valuable metals are presented.

Jan 1, 2016

By Fiseha Tesfaye, Pekka Taskinen, Daniel Lindberg

Due to increasing complexities of raw materials for base metals production the conventional pyrometallurgical processes are challenged. To make the appropriate modifications, thorough evaluations of the thermal stabilities of phases and phase assemblages which are commonly encountered in these processes are essential. In this work, phase relations and thermal stabilities of equilibrium phases in the Cu-Ni-S system have been reviewed. The calculated phase diagram of Cu-Ni system has been validated. At T < 630 K, in the Ni-rich corner, large scatter in data has been observed and discussed in detail. The other binary systems, Cu-S and Ni-S, have been also critically reviewed together with the ternary Cu-Ni-S system. The reviews were focused on compiling and discussing phase relations and thermal stabilities of the selected systems in the pyrometallurgical processes of Cu and Ni productions.

Jan 1, 2016

By Shengli Wu, Mingyin Kou, Laixin Wang, Xinliang Liu, Zhennan Qi, Yujue Wang

Softening and melting experiments were conducted on four kinds of imported lump ores named A-D, under different temperature intervals within the self-developed visualization high temperature furnace. By calculating the reduction and shrinking degree under different intervals, softening and melting indexes were determined. These ores all expanded firstly followed by shrinkage with the temperature increasing. The difference of lump ore’s own characteristic led to different softening and melting behavior. The results showed that the looser the structure was, the better the reducibility will be. The compact structure and good reducibility led to high expansion rate. The beginning softening temperature declined and the ending softening temperature increased because of high porosity, which resulted in wide softening temperature interval. The charging ratio of lump ore A should be improved. Lump ore B should be distributed in the center of the blast furnace. Lump ores C and D should be used less.

Jan 1, 2016

By S. Redik, C. Wenzl, D. Gregurek, A. Spanring

Zinc is a component of many input materials used in various pyrometallurgical processes, for example primary lead and zinc production from Pb/Zn ores and recycling processes dealing with zinc-containing residues (e.g., copper recycling, WAELZ process). Hence, zinc and its compounds are present in the respective metallurgical vessels and interact with the refractory lining. In the present work the zinc attack on the refractories out of various primary and secondary furnaces is briefly introduced and discussed. At the prevailing processing temperatures in the metallurgical vessels, zinc oxide is highly corrosive for the brick components. The knowledge of the wear behavior is based not only on a detailed chemical and mineralogical characterization carried out on provided post mortem samples, but also on FactSage calculations. This together with results obtained by practical testing in the RHI pilot plant represents an important prerequisite for product development and brick selection for the individual customer application.

Jan 1, 2016

By Shengli Wu, Mingyin Kou, Feng Chang, Laixin Wang, Hua Lu, Jianliang Zhang

Sintering dust has been regarded as an important secondary resource in a modern steel plant. Sintering dust was mechanically treated using different milling machines and experimental conditions in air atmosphere. The changes in phase constitution, particle size, specific surface area, particle morphology, and lattice parameters of activated sintering dust were determined. It was found that the agglomeration of the particles take place during extended dry milling with accessible pores for Nitrogen gas. The maximum specific BET surface area in the stirring wet grinding and planetary wet grinding increases to 43.06 and 46.45 m2/g after activated 360 min respectively. With the increasing of energy input, the intensity of diffraction peaks of dolomite and hematite gradually decreased. Furthermore, the previous phase almost disappeared eventually under any experimental conditions. In addition, Fourier transform infrared spectroscopy indicates that organic matter and carbonate decompose easier than other phases, especially under stirring wet milling.

Jan 1, 2016

By Xuemei Zheng, Aiyuan Ma, Chao Liu, Guojiang Li, Chenyu Sun, Jinhui Peng, Libo Zhang, Yongguang Luo

In this paper, the removal of fluorides and chlorides from blast furnace dusts by water vapor enhanced microwave roasting was investigated, combined with the advantages of microwave selective heating and based on a thermodynamic analysis of zinc and lead halides. According to proposed reactions in the process, detailed experiments were systematically conducted to study the effect of roasting temperature, holding time, air flow, water vapor flow rates, and stirring speed on the efficiency of the removal of F and Cl. The results show that 97.26% of F and 64.23% of Cl could be separated when the condition of the roasting temperature of 650°C, stirring speed of 80 rpm, holding time at 60 min, air flow of 350 L/h and water vapor flow rate of 8 mL/min was optimized.

Jan 1, 2016

By Yousef Mohassab, Manoranjan Misra, Monalisa Panda, Eman Wahbah

This work studies the removal of arsenic (V), arsenate, and arsenic (III), arsenite, from aqueous solution using calcined Quintinite-3T. The two adsorbents Quintinite-3T was prepared, calcined at different temperatures, and characterized by XRD, BET, and SEM. The surface area of the calcined Quintinite-3T was 193.4 m2/g. The particles size ranged from 12 to 56 nm for the uncalcined Quintinite-3T and from 24 to 42 nm for the calcined Quintinite-3T. Kinetic analysis, adsorption isotherm, and factors affecting the adsorption were investigated. Calcined Quintinite- 3T retained As(v) and did not release it back to water even after an entire month.

Jan 1, 2016

By Oscar Jaime Restrepo, Juan Camilo Restrepo, Jorge Ivan Tóbon

Portland cement is obtained by a conventional synthesis process from a mixture of limestone and clay at high temperature (1450 °C). This work reports the possibility to obtain cement silicates via alternative methods like Solution Combustion Synthesis (SCS), which optimize both time and temperature, and the consequences to energy efficiency and mitigation of CO2 emissions. The production of one ton of cement emits between 0.62 and 0.97 tons of CO2 into the atmosphere. In this process the CO2 emissions are between 21 and 59%. The combustion methods are chemical redox processes in which, at high temperature, a self-sustaining and fast wave is generated from using chemical precursors and organic fuels.

Jan 1, 2016

By S. Eckert, G. Gerbeth, K. Timmel, B. Willers, T. Wondrak, N. Shevchenko, M. Röder

The quality of the produced steel in the continuous casting process is significantly governed by the melt flow in the mold. However, direct flow measurements in liquid metals are still rather scarce. In order to investigate these flow phenomena, three experimental facilities operating with low melting liquid metals were installed at Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The melt flow in the models is measured by the Ultrasonic Doppler Velocimetry (UDV) or the Contactless Inductive Flow Tomography (CIFT), multi-phase flows can be visualized by X-ray imaging. The obtained measurement results are primarily used for validation of numerical models. In this paper we will investigate the fluid flow in the mold and the behavior of the surface of the liquid metal using flow measurements by UDV and surface profile measurement by a laser scanner, respectively. Strong fluctuations and deviations of the free surface were observed in case of a static magnetic field

Jan 1, 2016

By Cong Wang, Siyang Long, Pengcheng Zhang, Haibin Zuo

The present study describes central segregation of the High-carbon steel billets of 150mm square and its heredity to the following hot-rolled wire rods, whose sizes are 10mm and 6.5mm in diameter separately. The relationship between center segregation of the billets and solute element distribution of rods, the mechanical properties and microstructure of rods were studied experimentally. The results show that segregation index of C is higher than that of Mn. With the increase of central segregation, the stability of the mechanical property of the rods becomes worse. The formation of carbide network and central martensite in the rolled products can be attributed to the heredity of the as-cast central segregation. The 6.5mm-diameter-rod has higher tensile strength than that of 10mm diameter which might be due to bigger reduction ratio. Thermo Mechanical Control Process (TMCP) should be used together with Billet Centersegregation- controlling (BCSC) to improve the overall properties of rolled products effectively.

Jan 1, 2016