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By Sheng-ping He, Zhuo Chen, Qian Wang, Kun-peng Xu

During the continuous casting (CC) process of Ti-Stabilized Stainless Steel, the nozzle clogging or even the crusts composed of TiN, Al2O3, TixOy and the complex inclusions MgOAl2O3, Al2O3 is often occurred. The main objective of the present study is to research the reaction between refining slag or mold flux and Ti-Stabilized Stainless Steel by thermodynamic calculation. A suitable refining slag composition was sought to absorb Al2O3, Tix Oy inclusions, and the reactions between different mold flux and steel was calculated and compared. It was found that a suitable refining slag was difficult to adjust aluminum and titanium to meet requirement simultaneously. The target refined slag is composited of 3–8.7% SiO2, 56–59% CaO, 33–38% Al2O3 and 4% MgO with low melting point and high absorption capacity of inclusions for in the refining of the 321 stainless steel. SiO2, Fe2O3, Na2O and B2O3 of mold flux would react with titanium in the steel. The CaO–SiO2 based mold flux had a strong reactivity than CaO–SiO2–Al2O3 and CaO–Al2O3 based mold flux.

Mar 1, 2017

By Leizhang Gao, Zhengfeng Qu, Pingsheng Lai, Chenguang Bai, Meilong Hu

FFC process could be used to prepare titanium foams. The mixed oxides CaO-TiO2 with mole ratio 1:2 were sintered into CaTiO3-TiO2 mixture. CaTiO3-TiO2 was then used as cathode and electrolyzed in molten CaCl2 to prepare porous titanium. The porous titanium with the porosity of about 72.15% was first fabricated. The internal pores are in the presence of circular cavities and the pore size is in the range of 50–100 lm. Compared with the powder metallurgy technique using the space-holder this method promises to be lower cost and less processing. It is potential to fabricate titanium foams using FFC process.

Mar 1, 2018

By Mohammad Mokmeli, Colin Oloman, Rod McElroy, William McWilliam, Bruce Downing, David Trueman, David Dreisinger

Lithium is anticipated to be a key, strategic material in the clean tech- nology economy. The majority of lithium reserves are contained in continental brines and sea water (>60%). Currently the most economical approach to recover lithium from such resources is through selective adsorption. Spinel type lithium manganese oxide and lithium titanium oxide have demonstrated to be excellent candidate materials (after de-lithiation). However, due to the small size of the powders, they have limited industrial application and require immobilization. In this work, we examine the application of novel manganese oxide nanowire composites for the extraction of lithium from dilute solutions. Manganese oxide nanowires were synthesized and simultaneously immobilized on diatomaceous earth via hydrothermal method. Lithium manganese oxide were then formed by solid-state reaction, de-lithiated and tested for lithium ion adsorption.

Mar 1, 2018

By Timothy W. Ellis, John A. Howes, Roger D. Feldman

The new generation of more powerful, energy-intensive devices for communications, industrial production, energy storage and other purposes is creating new challenges to guard against environmental harm and protect national security. Many devices are designed, used and disposed of in a linear, rather than circular manner. This causes scientific, legal and economic issues because the life-cycle costs of components are not adequately considered. Dealing with these issues in isolation from each other can lead to unintended consequences. New models to confront these issues are being defined. This paper suggests a fundamental tool for dealing with material science issues while taking into account the engineering, economic and policy perspectives. That tool is the development of a true, levelized cost of energy storage model with a wide spectrum of inputs for comprehensive analysis. This paper will discuss inputs and the process which can yield meaningful, useful comparisons among batteries and energy-intensive products.

Mar 1, 2018

By James C. Withers

There is no production of rare earth metals in the U.S. in spite that the U.S. is the largest consumer of rare earths in some form that includes consumer and Department of Defense (DoD) devices. The one U.S. mine has been purchased by the Chinese that even enhances their monopoly on rare earths. A research effort has demonstrated rare earth oxides can be extracted from bastnaesite ore as well as coal ash at efficiencies in the upper 90s percent. The rare earth oxide can be carbothermically treated to produce an oxycarbide which is highly electrically conductive. The rare earth oxycarbide can be used as an anode in anhydrous fused salts electrolysis to produce a highly purified rare earth powdered metal. It is also possible to electrofractionate the individual metals which can be combined with co-deposition of iron and boron to produce the highly magnetic alloy Nd2Fe14B.

Mar 1, 2018

By Henrik Gudbrandsen, Anne Støre, Ana Maria Martinez, Karen Sende Osen, Ole Kjos

The light rare earth metals Nd, Pr, La, Ce as well as some alloys with Fe, are today produced in China by electrolysis in molten fluorides using oxide raw materials. A major challenge is to obtain a good cell operation without de-composing the electrolyte leading to emissions of per fluorinated carbon (PFC) green-house gases to the atmosphere. This work is focused on understanding the fundamental requirements to run the electrolysis cells for DyFe alloy production in an ef ficient and environmental friendly way. Electrolysis experiments was carried out in DyF 3-LiF melts at 1050 °C. A Fe rod was used as consumable cathode and the (consumable) anode was made of graphite. To establish at which anode potential PFC occurred and thus enabling optimisation of the oxide batch feed rate, analysis of the anode gases was performed with Fourier Transform Infrared Spectrometer (FTIR). The produced DyFe alloy was characterised by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS).

Mar 1, 2017

By I. Filzwieser, S. Wallner, M. B. Hanel, A. Filzwieser

Whenever thinking about increasing tankhouse performance two major aspects has to be considered, the technological feasibility as well as the economical impact. For meeting the requirement of an increased current density leading to an increased productivity, Mettop has developed the METTOP-BRX Technology, which allows the introduction of fresh electrolyte between each pair of anode and cathode. As an example of a green field approach the installation at Xiangguang Copper Co., Ltd will be described. Since the start up in 2011, Xiangguang Copper Co., Ltd operates one of their two copper refining tankhouse with a current density of 420 A/m2 and a current efficiency above 98% in average. At Montanwerke Brixlegg Ag, as an example of a brownfield installation, the annual production could be increased by 50%. Although for many years a total of two industrial applications are in operation, the successful implementation of this technology that result in significant operational and economic advantages has not been fully accepted within the industry due to misunderstandings, incorrect interpretations and lack of awareness. It is intended with this paper to create a better understanding about the parallel flow technology and help to eliminate worries and concerns.

Mar 1, 2017

By Jilai Xue, Shuming Huang, Zengie Wang

The corrosion behaviors of chrome corundum/magnesia in laterite nickel slag were investigated by static crucible method. The results show that the molten slag can penetrate into chrome corundum or magnesia which are used as lining materials in smelter furnace, and the corrosion can occur at the slag-refractory interface and the inner area of the refractories as well. Both the penetrated amount of slag and the penetration depth of Fe, Si increase with increasing FeO content (10–25 wt%) in slag. Such penetration in magnesia is stronger than that in chrome corundum under the same corrosion conditions, as more pores in magnesia may provide channels for slag penetration and corrosion product transportation. A damage of the refractory linings and short service life of smelter furnace may happen during metallurgical processing slag with high FeO content.

Mar 1, 2017

By Kevin Trumble, David Johnson, Kyungjean Min

The electrolytic manganese dioxide (EMD) production through electrodeposition from manganese nodules by reduction leaching in H2SO4 medium using sucrose as reductant followed by purification through 2-stage precipitation methods is described. The purified leach liquor was the starting solution for electrodeposition. Influence of in situ addition of a cationic surfactant Cetyltri-methylammonium bromide (CTAB) (0–500 mg dm −3) on the surface morphology and electrochemical properties of the EMD was examined. The XRD patterns of the deposited material were indexed to the c-MnO2 phase. FESEM results demonstrated that in the presence of CTAB uniform nanofibrous type grains were formed. Higher concentration of CTAB in the electrolytic bath however, drastically decreased the current efficiency (CE) and increased the energy consumption (EC) during electrodeposition. Under the optimum CTAB concentration of 100 mg dm −3 the obtained CE and EC values were 87.64% and 1.70 kWh/Kg respectively.

Mar 1, 2018

By Wei-Tong Du, Xiao-Ping Liang, Yu Wang

The structural properties for ternary molten CaO–SiO2–B2O3 system with varying B2O3/SiO2 ratios at a fixed CaO content were calculated by molecular dynamics (MD) simulation. The simulation results revealed that with the increasing of B2O3/SiO2 mol ratio, the bond length of B-O was approximately constant at 1.35 Å, and the coordination number for B (CNB-O) was observed to vary from 3.40 to 3.51, and the average angle of O-B-O increases from 105° to nearly 120°, implying that the geometric stability of structure is reducing sharply. AlsoQ3 andQ4 tetrahedral species (tetrahedron with three and four bridging oxygens respectively) decrease with the increasing of B2O3/SiO2 mol ratio, and the proportion of (Q3 + Q4) decrease linearly from 0.6 to nearly 0, suggesting that B2O3 may behave as a network-breaking basic oxide in the CaO–SiO2–B2O3 system.

Mar 1, 2017

By Ming Li, Li Ma, Yunqing Tian, Haoyu Cai, Luyao Zhao, Wenwang Liu, Wenbin Huang, Gele Qing, Yan Zhang

In this paper, study on the in fluences of different Ti-bearing materials on MgO-bearing pellets metallurgical properties was carried out. The results show that, pellets compression strength will decrease while using ilmenite. However, TiO2 reagents help to improve pellets compression strength. The reduction swelling decreases while using TiO2 reagents, but different ilmenites have diverse impacts on the reduction swelling. Pellets compression strength will decrease and reduction swelling will be improved while adding magnesium additives. In order to produce qualified Magnesium-Titanium bearing pellets, the firing temperature should be no less than 1270 °C.

Mar 1, 2018

By P. Kim, M. Tangstad, T. Larssen, R. Kawamoto

The reduction rates of MnO and SiO2 were investigated for various charge compositions. The empirical activation energies of MnO and SiO2 reduction from SiMn slags were calculated between 1500 and 1650 °C under CO atmospheric pressure. The amounts of metal produced at different temperatures were compared, and the Arrhenius plots were described for each slag A, slag B and synthetic slag, which shows that the raw material have significant influence on the reduction rate. The rate of Mn-produced in slag A was faster than slag B despite of the relatively lower driving force. The lower rate constant in slag B implies that other kinetic factors, such as viscosity, affects the reduction rate. The estimated activation energies of MnO were 920, 304 and 975 kJ/mol MnO for slag A, slag B and synthetic slag, respectively. The rates of Si-produced were similar and slow for all slag types. However, the different activation energies of SiO2 between industrial ores and synthetic materials implied that the trace elements can have catalytic effects toward SiO2 reduction in SiMn slags. The estimated activation energies of SiO2 reduction were around 800 kJ/mol for slag A and slag B.

Mar 1, 2017

By S. Niyomwas, T. Chanadee

The influence of flux CaO2–Al ratio on the Self propagating high temperature synthesis (SHS)-casting reaction products in WO3–Si–Al system has been investigated in this study. Incorporation of CaO2–Al amounting to 1–5 wt% of total charge has been found to be adequate to form WSi2 intermetallic with a maximum hard-W5Si3 secondary phase. The micro-hardness of tungsten silicides intermetallic product increased significantly with CaO2–Al ratio. The as-SHS-casting products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersive x-ray (EDX) technique.

Mar 1, 2017

By Fabiano A. C. M. Passos, Vanessa P. R. Silva, Lillian M. B. Domingos, Fernanda A. N. G. Silva, Zuleica C. Castilhos, Roberto B. Faria

Wastes from gold mining need to be monitored from the beginning of mining activities until to the mine closure. Wastes from tailings dam were characterized by XRD, XRF, elemental analysis of carbon and sulfur and ICP-OES. In flotation waste (FW) were observed quartz, dolomite, pyrite, muscovite and chamosite were observed. Meanwhile, in cyanidation waste (CW), besides those described in FW, minerals such as sphalerite, galena, pyrrhotite, microcline and albite were detected, indicating a higher concentration of sulfide minerals in the cyanidation waste. In relation to C and S content, to FW and CW, they were 2.5 and 0.0% and 0.64 and 15.4%, respectively, confirming the majority of sulfides at CW sample and indicating the absence of the flotation organic reagents at the cyanidation waste. The analysis by ICP-OES indicated As, Zn, Pb, Cr and Cd content for FW and CW: 13.30 and 343 mg/kg; 399 and 7,900 mg/kg; 136 and 13,000 mg/kg; 130 and 260 mg/kg; 3.60 and 84.60 mg/kg, respectively. It was also verified significant levels of heavy metals, which indicates the necessity of performing wastes toxicity tests.

Mar 1, 2017

By Shengfan Zhou, XUEWEN WANG, Fuhong Xie, Qi Ge, Bianfang Chen, Biao Liu, Mingyu Wang, Sheng Huang

To recover iron, titanium, vanadium and chromium from vanadium bearing titanomagnetite, a process of direct reduction has been proposed. After magnetic separation, a material containing titanium, vanadium and chromium was obtained. In this paper, a salt-roasting process was proposed to extract vanadium and chromium from the material containing titanium, vanadium and chromium. The effects of the several parameters that included roasting temperature, roasting time and the addition of sodium carbonate were investigated. Under the most suitable conditions including a roasting temperature of 900 °C, roasting time of 2 h and sodium carbonate addition of 33 wt%, the leaching of vanadium and chromium reached 91.2 and 68.4%, respectively. After leaching, the leach residue can be used as the raw material for extraction of titanium.

Mar 1, 2018

By Yungang Li, Hui Li, Ramana G. Reddy, Jinglong Liang

High solid corrosion protective coatings were prepared by the dust of the converter with an average particle size of 59.33 μm. The effect of different amount of benzyl alcohol diluent on the performance of high solid anti-corrosion coatings was studied. With the increase of the amount of diluent, the viscosity of high solid anti-corrosion coatings reducing, the film apparent bubble content decreasing, and film resistant to salt water corrosion ability decreased, while acid corrosion capacity enhancement. When the dosage of diluents is 15%, the coating film is more resistant to acid corrosion.

Mar 1, 2017

By Zheng-qi Guo, De-qing Zhu, Feng Zhang, Jian Pan

Iron mainly exists as the magnetite and fayalite, while copper is primarily dispersed in the form of fine matte particles in the copper slag, which is difficult to recover by conventional separation techniques. In this paper, the feasibility of an integrated technological route to improve beneficiation of copper and iron components from copper slag through the modification of molten slag was investigated, and the results shows that: the copper grade of rougher copper concentrate was increased from 6.43 to 11.04%, iron recovery from magnetic separation was increased significantly from 32.40 to 63.36%, and other evaluation indexes were changed slightly, in comparison with unmodified copper slag. Meanwhile, the grains of the target minerals in the modified slag grew considerably to a mean size >50 lm after slow cooling. Ultimately, the beneficiation efficiency of copper and iron was improved because of the ease with which the target minerals were liberated.

Mar 1, 2017

By He Jing, Wang Changhong, Chen Yongming, Wu Yanzeng, Yang Xiyun, Tang Chaobo, Yang Shenghai

Pitting of Hf in Et4NBr t-butanol and acetonitrile (ACN) solutions was studied by means of cyclic voltammetry, potentiodynamic anodic polarization,galvanostatic, potentiostatic and impedance techniques. The potentiodynamic anodic polarization curves did not exhibit an active dissolution region near corrosion potential due to the presence of an oxide film on the electrode surface, which was followed by pitting corrosion resulting from the passivity breakdown by the aggressive attack of bromide (Br−) ion. The pitting potential (Epit) increased with increasing potential scanning rate but decreased with increasing temperature and Br− concentration. Cyclic voltammetry and galvanostatic measurements allowed the pitting potential (Epit) and the repassivation potential (Ep) to be determined. Analysis of the potential/time transients revealed that the applied anodic current density had a significant influence on the values of Epit. On the other hand, the Ep values were independent on the applied current density. The current/time transients indicated that the incubation time (ti) for passivity breakdown decreased slightly with increasing potential and solution temperature. The impedance spectra showed that the resistance of passive layer decreased with increasing potential.

Mar 1, 2017

By Metehan Erdogan, Mustafa Serdal Aras, Sedef Cift Karagul, Ishak Karakaya, Esra Karakaya, Merve Kolay Ersoy

Pickling is the treatment of metal surfaces by removing oxide layer, rust, scale, inorganic contaminants or other impurities from ferrous metals, copper or precious metals. A strong inorganic acid such as hydrochloric acid is used for plain carbon or low alloy steel pickling. When the concentration of copper in the pickling solution exceeds about 100 mg/L, reversion may take place and randomly plating of copper onto the steel strips which causes visual incompatibility occur. Furthermore, efficiency of pickling decreases with the increase of copper content. The reversion may be delayed to higher Cu concentrations by adding fresh acid to the line. Increased acid consumption only delays the time to discard the solution but increases the cost and hazardous nature effect on the environment. An experimental electrochemical procedure has been conducted to remove copper from pickling solution to reduce the concentration below 100 mg/L. Within this scope, effects of applied current density, copper concentration and electrolysis duration on copper deposition were studied. Current density was determined as the most effective parameter to remove copper from the regenerated pickling solutions of steel plants.

Mar 1, 2018

By Naiyang Ma

Along with steel production, various steelmaking slags are constantly generated at considerably high rates. In general, steelmaking slags are not categorized into hazardous materials and do not cause any environmental issues. Therefore, recycling of steelmaking slags is often aimed at creating values by using the slags to replace high-cost raw materials. Chemical compositions and particle size distributions of slag products from steelmaking slags will determine what raw materials the slag products can replace. Consequently, maximizing the values of steelmaking slags will require to produce slag products with the highest values and to process the slags with the lowest costs. In this paper, several slag processing processes are assessed based on maximization of the values of the steelmaking slags.

Mar 1, 2017