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By Lingling Zhang, Daqiang Cang, Guizhou Zhao

Pilot trial ofthe detoxification ofchromium slag in cyclonefurnace and the preparation of glass-ceramics were investigated in a power plant in China. 10wt.%chromiumslagweremixedwithpulverizedbituminouscoalandlimestone as the raw materials of the cyclone furnace. Cr(VI) in chromium slag was reduced toCr O insidethecyclonefurnace.Themeltwaswater-quenchedintofritandthen 2 3 fired into glass-ceramics with a laboratory ceramicrollerkiln. The preparation and crystallization behavior of glass-ceramics were investigated with differential ther- mal analysis (DTA), physical and mechanical properties testing, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optimal flexural strength exceeding 90 MPa were achieved in firing temperature zone of 1170–1200 °C. Anorthite (CaAl Si O ) and diopside [Ca(Mg, Fe)Si O ] can be identified in the 2 2 8 2 6 glass-ceramicsandCaAl Si O isthepredominantcrystalphase.Fineparticleswith 2 2 8 average diameter of 200 nm distributed uniformly in the glass-ceramics. Granular crystals are intensively interconnected and constituted a crystal skeleton soaked in theglassmatrix.LeachingtoxicitytestdetectedCr(VI)of0.016and0.010 mg/Lof the water-quenched frit and glass-ceramics, respectively. This method provides an effective and comprehensive technique for the detoxification and utilization of chromium slag at low cost and large-scale. (cid:1) (cid:1)

Mar 1, 2018

By Jiongtian Liu, Guihong Han, Shuzhen Yang, Yanfang Huang

Binder, as a necessary functional material of electrode in lithium ion battery, has a vital influence on the electrochemical performance. The humics, coupled with polyacrylamide (PAM) and sodium carboxymethyl cellulose (CMC), were used as a water-soluble binder for LiFePO4 (LFP) cathode using in lithium ion battery. The techniques of cyclic voltammetry (CV) and galvanostatic charge-discharge were conducted to evaluate the performance of humics binder in LFP electrode. The reversible specific capacity of LFP (HA + PAM + CMC) electrode can reach to 142 mAh g−1 after 50th cycling (100 mAh g−1) on conditions of raw materials with 1 wt% PAM addition, humics and CMC with a mass ratio of 3:1 in binder, and the raw materials mixed in an interval order. Humics has the potential to be used as a novel, eco-friendly and high-efficient binder for lithium-ion battery.

Mar 1, 2018

By Manuela Castaneda, Henry A. Colorado

This paper is about the use and stabilization of iron oxide based powders with arsenic contents coming from the purification of water. Cement paste samples with 0.0, 2.5, 10 and 20wt% of waste were fabricated by mixing mechanically all components. There are two main positive impacts of using this waste, first, this waste is produced in large amounts worldwide, and therefore the stabilization has a significant impact for the environment. Second, the waste can be used as an admixture and filler for cement, and therefore reduce the amount of cement in the concrete, which has a major impact in the CO2 footprint since cement industry produces a lot of this gas. Compressive strength and density tests were tested after 28 days. Microstructure was analyzed with scanning electron microscopy and x-ray diffraction. Results show that compressive strengths greater than 20 MPa were obtained and the samples had calcite, portlandite and ettringite phases.

Mar 1, 2018

By Marcel Magnusson, Guozhu Ye, Pekka Vaananen, Yang Tian

The most used technology for recycling of spent alkaline batteries consists of crushing, magnetic separation and processing of the nonmagnetic fraction, black mass, using a rotary kiln. In the process only zinc is recovered and all manganese in the black mass is lost. According to the EU regulation for recycling of batteries, more than 50% of batteries should be recovered. To meet the demand, Swerea MEFOS has together with a major battery recycler IsoLogistics in Finland and Sweden developed technologies for efficient recovery of zinc and manganese aiming for >50% recovery. This paper will focus on a treatment process using a DC furnace to produce a ZnO- and a MnO-product. The process has been demonstrated in pilot scale, 1 ton/h. The major outcomes will be highlighted. Another approach by using thermal vacuum technology for distillation of zinc metal has also been demonstrated in laboratory scale which is also reported in this paper.

Mar 1, 2018

By Guozhi Lyu, Ting-an ZHANG, Biyu Long, Yajing Tian, Xuejiao Cao, Weiguang Zhang

Aim to the separation problem of high concentration V–Fe in stronger acidic leaching solution of vanadium slag, a novel chelating extraction system is proposed to separate V and Fe. Influence factors including initial pH value, the extractant concentration, the phase ratio, temperature and time are investigated. The experiment results show that single extraction rate of V and Fe reach 85.57 and 0.39% respectively, when pH value is −0.4, organic phase composition is 30% Mextral 973H + 70% sulfonated kerosene oil, O:A = 1:1, stirring time is 10 min, extraction temperature is 30 °C. The industrial experiment results of three levels countercurrent extraction show that the total extraction rate of vanadium and iron can reach 97.44 and 0.23%, separation factor is 6410. The effective separation of V and Fe in high acid and high iron solution can be accomplished.

Mar 1, 2018

By Wufeng Jiang, Jiann-Yang Hwang, Suju Hao, Yuzhu Zhang

Magnetite powder and coke powder were used as experimental materials and H2 as reducing agent in a high temperature vacuum tube furnace. The change rules of magnetite powder (MP), mixed coke powder and magnetite powder (MCMP), and carbon coated magnetite powder (CCMP) in the process of reduction were studied. The samples were determined by field emission scanning electron microscopy and X-ray diffraction. The results show that, with the increase of reduction time, the reduction degree of magnetite powder is improved. Under the same reduction conditions, the addition of coke powder improves the reduction rate. Compared with MP, when the reduction time was 120 min, the reduction degree of MCMP was 30% greater; and the reduction degree of CCMP was 39% greater. The mixed grinding of magnetite powder and coke powder is a better way to add carbon. Under the same reduction conditions, compared with MCMP, the reduction degree of CCMP was 9% greater when the reduction time was 120 min. After the reduction of CCMP, the number of pores in the sample increased and the structure was loose. The results of this study have some reference value for improving the reduction rate of magnetite powder.

Mar 1, 2018

By Chen Qizhou, Wang Yun, Zhu Rong

SiO2 and Al2O3 in the metallurgical slag of nickel laterite ore have great recycling values. In this work, Si and Al were extracted from the slag in NaOH based molten salts through alkali roasting and water leaching process for preparing zeolite materials. The extraction ratio of SiO2 increases with increased temperature and appropriately prolonged time, and more than 80% SiO2 can be recycled from the slag after roasting at 550°C. Si and Al from the slag are in the filtered liquor for producing zeolite materials, while Mg, Ca, Fe and other impurities remain in the leached residues. Adding Na2CO3 into the alkalin-slag roasting process can reduce the amount of pure NaOH used with minor decrease in extraction ratio of SiO2, while make better separation of Ca to avoid it getting into the filtered liquor. Adding Al2O3 into the alkalin roasting process can replace part of more expensive NaAlO2 addition that is required for preparing zeotite material, which may bring out a minor decrease in extraction ratio of SiO2 due to formation of NaAlSiO4 in the filtered residues. Quality X zeolite and 4A zeolite materials can be made from the starting liquor containing Si and Al recycled from the laterite nickel slag through alkali roasting and water leaching process.

Mar 1, 2018

By Jun Li, Lingling Zhang, Daqiang Cang, Guizhou Zhao

Pilot trial of direct modification of molten blast furnace slag and production of high acidity coefficient slag wool fibers were investigated nearby a blast furnace. Molten blast furnace slag discharged from blast furnace and then directly flow into specialized modification furnace and quartz was simultaneously added into the molten slag as modification agent. The modified molten slag was electric heated to 1500–1550 °C and then the melt was produced into slag wool fibers through high-speed centrifugation method. Melt with acidity coefficient of 1.2, 1.4, 1.6 and 1.8 were investigated and fibers with corresponding acidity coefficient were produced. Slag wool fibers with shot content of 5.5, 5.8, 6.2, 6.8% and average diameter of 4.5, 4.9, 5.6, 6.4 lm for four samples were successfully produced, respectively. Total energy consumption and production costs decreased by 50–70% compared to traditional cupola furnace method. This method provides an energy-saving and emission-reduction technology for the direct utilization of molten blast furnace slag.

Mar 1, 2018

By Guihong Han, Wei Wang, Chaolei Lv, Yongsheng Zhang

Silica aerogels are promising in many applications because of their excellent properties. However, the real applications of pure silica aerogels are limited because of their fragile network structure. We have prepared silica aerogel composites using humic acid as a composite material for improving the performance of silica aerogels and valorization of humic acid. The silica hydrogel composite was prepared using sodium silicate as a precursor and humic acid as a composite material by acid-base catalysis and sol-gel method. The hydrogel was followed by freeze-drying to obtain composite aerogel. The microstructures, specific surface area, and functional groups of silica and composite aerogel were characterized using scanning electron microscope (SEM), brunauer-emmett-teller (BET) and fourier transform infrared spectrometer (FTIR). The results demonstrated that the specific surface area of the silica composite aerogel was 307 m2/g under the condition of pH at 6, the mass ratio of silicon to humic acid (HA) at 3.82 and the molar ratio of N, N-dimethylformamide (DMF) to silicon at 0.9. X-ray diffraction (XRD) showed that the silica (composite) aerogels were amorphous. Thermogravimetric analysis (TGA) revealed that the silica aerogels lost weight from 150 to 250 °C and humic acid decomposed between 350 and 500 °C, and then the mass of the sample remained stable.

Mar 1, 2018

By Keiji Watanabe, Hiroyuki Tobo, Yasutaka Ta, Hisahiro Matsunaga

Recently, effective utilization of by-product slag as aggregate for concrete has been expected from the viewpoints of depletion of natural crushed stone and suppression of environmental loads. We developed a new process for continuous solidification of blast furnace slag as coarse aggregate. In this process, molten slag is continuously poured into molds, and the slag is solidified at the thickness of 20–30 mm. The flow rate of the molten slag is 1 t/min, and maximum production per ladle is about 30 t. After solidification, blast furnace slag coarse aggregate (BFG) is produced by crushing and adjusting the particle size of the solidified slag. The new BFG has water absorption of less than 1%, and concrete containing the BFG has the same fresh property and compressive strength after 28 day as concrete using natural crushed stone aggregate.

Mar 1, 2018

By Chengyi Ding, Xuewei Lv, Senwei Xuan, Chenguang Bai, Kai Tang, Gang Li

Sinter is an important iron-bearing material charged into blast furnace. Calcium ferrite (CF) is one of the most significant liquid phases in fluxed sinter. The isothermal reduction kinetics of CF and CF8M (n(CaO):n(Fe2O3) = 1, wt%(MgO) = 8) with 30% CO and 70% N2 gas mixtures at 1123, 1173, and 1223 K were investigated through thermogravimetric analysis in this study. Rate analysis illuminates that the reduction processes of CF and CF8M are mainly expressed as a typical two-stage reaction. Sharp analysis indicates that CF and CF8M reduction is expressed by the Avrami–Erofeev equation presenting a 2D shrinking layer reaction. The apparent activation energy values of CF and CF8M reduction are 46.9 and 31.8 kJ mol−1 individually based on model-free method.

Mar 1, 2018

By Yunqing Tian, Wenbin Huang, Weidong Zhang, Xiaopeng Wang, Gele Qing, Xiangjuan Duan

Pellet production requires iron ore concentrates have fine particle size, high specific surface area and good balling performance, so iron ore concentrates appropriate for pelletizing is limited compared to sintering. In order to extend the iron ore resources for pelletizing, the iron ore fines for sinter are studied in this paper.The effect of grinded iron ores o npelletizing, roasting and pellet quality were studied in this paper. The bond grinding index of iron ore fine is between 12.5 and 16.98 kwh/t. The grinded iron ore fine has good balling performance, the drop number and compressive strength of green pellet were improved with increase of grinded iron ore fine ratio. The compressive strength of roasted pellets were decreased with increase of grinded iron ore fine ratio, however it can be reached 2500 N.P −1 while proportioned with more than 80% of magnetite iron ore concentrate.

Mar 1, 2018

By Bowen Li, Canhua Li, Mingsheng He

Steelmaking slag is a by-product in considerable volume and a valuable material for various applications. In general, steelmaking slag is an alkaline compound of CaO, Fe2O3, and SiO2. However, its characteristics varies depending on the feedstocks, steelmaking process and cooling method of the slag. To utilize this by-product effectively, this study investigated the characteristics of steelmaking slags taken from Wuhan Iron & Steel Co. Ltd. The results showed that the slags mainly consist of the oxides of calcium, iron, and silicon, with low contents of magnesia, alumina, and manganese oxide with a feature of high alkalinity and lime saturation factor. The major mineral phases include belite, calcium ferrite, calcium hydroxide, wustite, quartz, and small amount of elite. Thermogravimetric analysis indicated the weight loss from ambient temperature to 800 °C is 8% in total. Melting test showed the glass transition temperature is between 1300 and 1350 °C, flow temperature is about 1400 °C. The slag samples investigated in this study can be considered as a typical glass-ceramic composite.

Mar 1, 2018

By Kristine Bruce Wanderley, Denise Crocce Romano Espinosa, Jorge Alberto Soares Tenorio

Magnesium is present in nickels leach liquor and it is often disposed in waste barriers. However, new technologies with the aim of recuperating magnesium and other metals in the liquor have proven that it is possible to reduce the amount of metal lost during nickel ore processing. In this context, high temperature crystallization removes magnesium, with a concentration of 8 g/L, as MgSO4 H2O from the leach liquor. Kinetic studies of this process are needed to evaluate the thermodynamics of the growth of crystals. Thus, this work aims to study the crystallization kinetics of MgSO4 H2O. Temperatures of 230, 210 and 200 °C were investigated in a batch crystallization system in solutions with pH2. Aliquots were taken at each hour up to 5 h of time residence and analysed by ion chromatography for magnesium concentration. The reaction mechanism as well as rate constant and activation energy for each reaction temperature were obtained

Mar 1, 2018

By Thomas Boundy, PATRICK TAYLOR

Indium recovery from liquid crystal display (LCD) waste has been the subject of over 50 peer reviewed publications over the last decade; however, the first commercial recycling facilities are just beginning to be built. The low value of indium in the LCD screen material has posed a major challenge to would-be recyclers. Uncommon material combinations and geometries have further challenged development. A review of published literature regarding extraction of indium from LCDs will be presented and themes of advantageous processes will be highlighted. Barriers to rapid expansion of any recycling technology in the form of manufacturin gpractices, environmental regulations, and geographic constraints will be discussed.

Mar 1, 2018

By Chengyi Ding, Xuewei Lv, Senwei Xuan, Chenguang Bai, Kai Tang, Gang Li, Yang Xu

Perovskite easily forms during sintering of vanadium titanium magnetite (VTM) and is unfavorable for the following blast furnace. Steelmaking can concomitantly produce a great quantity of oxidized scale composed mainly of FeO and Fe3O4. Calcium ferrite (CaOFe2O3, CF) can be formed by oxidized scale with lime in air atmosphere and then added to the VTM during sintering. X-ray diffraction (XRD) results indicated that perovskite is not generated at low temperature but only when the temperature increases to 1473 K in the CF–TiO2 system. Therefore, VTM sintering can be performed with a low-temperature process with doping of CF. Perovskite formation is mainly divided into two steps. First, CF melts and produces CaO. TiO2 and CaO then combine to produce perovskite. This paper also discussed the reaction mechanism of CaO–Fe2O3–TiO2 ternary system to compare the generation routes of perovskite.

Mar 1, 2018

By Deng Ma

In order to obtain the solubility of carbon in vanadium-bearing hot metal, graphite powder is used for the carburization experiments. The other kinds of carburizers, namely low nitrogen carburizer, anthracite and coke are used for carburization of vanadium-bearing hot metal weighing 500 g at temperature of 1450, 1500 and 1550 °C respectively. Carbon increments of low nitrogen carburizer, anthracite and coke fall in descending order. It was found by comprehensive analysis that anthracite is the most cost-effective carburizer among three carburizers. Magnitude of apparent rate constant of carburization reactions is 10−4s−1. It is found that the carburization rate increase with temperature.

Mar 1, 2018

By Juliana Augusto Molari, Deborah Dibbern Brunelli, Leonardo G. de Andrade e Silva, Patricia N. S. Poveda

There are several additives aimed on improving the processing characteristics as well as mechanical properties of the plastic materials. Being polypropylene is one of the main polymers used in the plastic processing industry due to its easy processability and application versatility, was chosen as the base resin for this study. Additives can aid the processing of polypropylene, either by promoting a better slip between the chains (lubricants), or by contributing to nucleation and crystallinity (nucleating). In this study, the raw materials copolymer polypropylene, lubricant (internal and external action), organic nucleating agent (metallic salt) and inorganic nucleating agent (metallic oxide) were considered. Mechanical tensile tests, Charpy impact and spiral flow to verify melt index were performed to characterize the samples with additives and standard (copolymer polypropylene). The interference of these additives with polymeric matrix was observed.

Mar 1, 2018

By Shengli Wu, Jiacong Zhang, Kai Gu, Bingjie Wen, Heng Zhou

In practical production process, the average of silicon content in hot metal (HM) of COREX process (the average is 1.58%) is obviously higher than that in blast furnace (the value is below 0.6%), which leads to an increase in the cost of steelmaking. In this work, the factors affecting and impact mechanism of silicon content in HM were investigated by statistical analysis using actual operating data. The analysis indicates that the fuel rate, binary basicity of slag and the temperature of HM are positively correlated with the silicon content, while the sulfur content of HM and binary basicity of burden are negatively correlated with the silicon content. On this basis, a back propagation neural network was developed to predict and control the silicon content in HM. All the findings of this work are useful for guiding and optimizing the COREX operation.

Mar 1, 2018

By Wangzhi Zhou, Jian Xu, Jing Zhang, Xuecheng Gong, Mingsheng He, Guohua Xie

Graphite, which has a unique stack structure that enables a small friction coefficient, is used as one kind of the best hearth rolls to support and convey silicon steel strip in continuous annealing furnace. However, the buildup formation in/on the surface of carbon sleeve has always been a worldwide difficulty in the silicon steel industry. Based on the analysis of the microstructure, topography and composition of the buildups, combined with simulation experiments, the mechanism of forming buildups is discussed. The results show that buildups experience the process from nucleating to growing-up, and buildups are formed by nano liquid phase sintering (NLPS). Meanwhile, some countermeasures to reduce or prevent the formation of the buildups are proposed.

Mar 1, 2018