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By Guangliang Wu, Dong-chang Huang, Xin-bin Liu

High temperature mechanical properties of 50Cr5MoV roll steel was investigated by Gleeble 1500 thermal simulator testing machine The morphology, composition and microstructure of fracture surface were observed and analyzed by OM, SEM and EDS The results are indicative of that, there are two brittle temperature zones of 50Cr5MoV roll steel at the temperature of 600°C~950°C and 1300°C~1450°C, respectively. The section shrinkage rate is less than 60% The fracture mode changes from mixed ones dominated by intergranular to toughness transgranular one with the increase of temperature at the range of 650°C~1300°C. The fracture is along the solid--liquid phase at the range of 1300°C~ melting point It is crucial to formulate the 50Cr5MoV casting technology, to prevent the cracks and improve the quality of 50Cr5MoV roll steel.

Jan 1, 2016

By Baozhong Ma, Qian Li, Yonggang Wei, Shiwei Zhou, Bo Li, Chengyan Wang, Hua Wang

The magnesium-rich nickel oxide ore (w (Ni) =1.09 %, w (MgO)=29.08 %) mixed with 6 % and 8 % anthracite were roasted at different temperatures. XRD and SEM/EDS techniques were utilized to characterize the phase and microstructure transformation of the ores. The results show that lizardite and chrysotile of raw ore were converted into forsterite and enstatite during reduction roasting process. Simultaneously, iron and nickel oxide were reduced and migrated from the initial magnesium silicate. Fe3Si were formed when the roasting temperature went up to 1300 ℃ and 1350 ℃, and a small amount of Ni was observed in it. Temperatures got too high were not benefit to the polymerization of ferronickel.

Jan 1, 2015

By Lijun Lu, Honghui Fang

This article carried out the experimental study on using desulfurization ash in steel slag composite material. This was done by investigating the desulfurization ash content in formula one and formula two samples on the influence of setting time and strength of mortar. Through this study the following conclusions were reached for formula one: (1) a setting time of more than 10 hours is required, (2) a dosage of desulfurization ash of 1 ~ 2% is optimal, where flexural strength is reduced by 10% ~ 23% and compressive strength reduced by 5.7% ~ 16.4%. The conclusions of formula two were: (1) when the dosage of desulfurization ash is within 5%, the setting time is within 10 hours; (2) when the dosage of desulfurization ash is 1 ~ 2%, the flexural strength is increased by 5 ~ 7% and the compressive strength is reduced by 1 ~ 2%. The results show that the formula two is better.

Jan 1, 2015

By Shengfan Zhou, XUEWEN WANG, Bianfang Chen, Mingyu Wang

Vanadium was leached from roasted stone coal by NaOH solution, and the effect of leaching temperature, leaching time, addition of NaOH, liquid to solid ratio, the grinding fineness of stone coal, and stirring speed on the vanadium leaching rate was studied. The kinetics analysis for the process is presented by the shrinking core model. The results show that the vanadium leaching ratio of roasted stone coal can be beyond 75% at the 6% NaOH addition, leaching temperature of 95°C, leaching time of 7h, liquid to solid ratio of 1.2mL/g, and grinding fineness of 0.111mm. The leaching process is controlled by interfacial reaction kinetics and the apparent activation energy was 59.36kJ/mol.

Jan 1, 2016

By V. B. Telles, J. A. S. Tenorio, J. O. Alves, D. C. R. Espinosa

"The world production of crude steel in 2009 reached 1.2 billion tons. For each ton of steel produced, 150 kg of steelmaking slag and 20 kg of steelmaking dust are generated. These are wastes with considerable production and limited applications, therefore this work studied the recovery of these wastes into useful sub-products. The slag was used as raw material in the production of rock wool (a thermo-acoustic insulator) and the dust was inserted in the iron ore sintering process. Results showed that produced materials have exceptional proprieties, therefore the recovery of these wastes can contribute to decrease extraction of non-renewable resources, reduce the costs and impact of disposals, and aggregate value to the slag and dust.1. IntroductionSteel production using Eletric Arc Furnace (EAF) has grown over 119 million tones in the last years. In 2008 30.7% of all steel produced, was obtained through EAF. In United States of America (USA) the percentage of this process in the production of steel was about 58% in 2008, while in 2000 this percentage was only 47% [1]."

Jan 1, 2011

By A. Galvan

High rate compressible media filter (CMF) tests produced exceptional total suspended solids (TSS) removal at hydraulic loading rates ranging from 97.8 to 122.2 m/h. The compressible media is manufactured from a robust resin fiber that can withstand low pH and temperatures up to 149 °C. The media porosity can be varied by applying compression onto the media. At 40% compression, the CMF can remove particles greater than 4 μ. Three synthetic test-samples were generated by Hazen Research Inc., (Golden, Colorado) to simulate the copper Pregnant Leach Solution (PLS), Raffinate and Electrolyte solutions used for the testwork conducted at their facility. The preliminary results showed that the CMF was very effective in removing TSS without the use of chemical conditioning from the above test-solutions with efficiencies of 98%, 97%, and 96%, respectively. Given the remarkably high hydraulic loading rates, the industrial equipment footprint would be minimized appreciably over conventional clarification and alternative filtration systems.

By Toshiaki Akahoshi

Keywords: Wasted catalyst, Hydrodesulfurization, Ammonium vanadate, Ammonium molyb-date, Hydrometallurgical process. The fundamental reactions have been investigated in order to develop a hydrometallurgical process for recovery of molybdenum and vanadium from wasted catalysts generated in the hy-drotreating desulfurization of heavy oil. The principal steps of the process are a mild oxidation roasting of the waste catalysts at temperature around 500°C, leaching of the target metal components with dilute ammoniacal aqueous leachates, selective precipitation of vanadic acid, and ammonium molybdate precipitation. The selective recovery of vanadium as vanadic acid is successfully performed using ammonium sulfate as a salting-out agent. Recovery of ammonium molybdate is based on large dependence of solubility of ammonium molybdate in ammoniacal solutions upon temperature and ammonium salt concentration. In this process, the solution after recovery of vanadium and molybdenum is recycled to the leaching stage of the roasted materials, and the ammonium salts in the process liquor is in the repeated use. Employment of am-moniacal system makes it possible to operate the roasting at much lower temperature than that for the currently operating process.

Jan 1, 2005

By Wei Gao, Qing-cai Liu, Cun-fang Lu, Huimin Zheng, Jian Yang, Chun-ling Yao

"Mercury in flue gas of coal-fired plants was concerned as another serious pollution when sulfur dioxide pollution was controlled now. The adsorbent made from fly ash by thermal precipitation sulfur to remove mercury in fuel gas from coal combustion plant, SEM, BET, TGA and other measurement methods were used to characterize the effect on surface morphology, sulfur distribution and specific surface. High temperature deposition furnace was applied to increase sulfur content in fly ash based adsorbents produced in lab. The study found that sulfur attached to the adsorbent surface, mesopore and microporous structure, increasing its sulfur content of adsorbent. Sulfur was filled in interspace as small molecule S2, S5, increased their surface area and enhanced their adsorption capacity. The specific surface area increased by thermal precipitation sulfur, and specific surface area which increased with increasing temperature.1. IntroductionThe mercury emission caused by human activity has accounted for 10%-30% of total mercury emission all over the world[11, and the emission from coal-fired power plant have a huge proportion of these emission caused by human activity. Active carbon microstructure and surface morphology play an important role in its adsorption capability, which offers the potential for controlling environmental pollutant, such as sewage, fuel gas, atmosphere and et al [2,31, because it is a material with high specific surface area that long been considered as an excellent adsorbent. At present, include activated carbon, fly ash, calcium-based sorbents and other novel adsorbents. The adsorption capacity and production cost were very important in the process of mercury removal by adsorbents, so the mercury removal has focus on developing adsorbents of highly-efficient. In particular, the waste of metallurgical from coal combustion and the others have a significant advantage about the cost, and they have the highly-efficient in mercury removal after modified to enhance their adsorption capacity, such as fly ash of coal-fired. Apart from specific surface area, element content, pore structure, and surface morphology of activated carbon have great effect on its adsorption ability. Compared to adsorbents without modification, active carbon impregnated with other elements, such as chlorine, sulfur, bromine and et al. had more excellent characteristics to remove specific pollutants."

Jan 1, 2011

By V. I. Lakshmanan, R. Roy

Base metals and PGMs are currently recovered from sulfide concentrates using pyrometallurgical processes. These processes suffer from several limitations such as being capital intensive, scaling problems, S02 emissions and long delay in value recognition. Alternative hydrometallurgical technologies have so far not been successful and currently total pressure oxidation and partial pressure oxidation hydrometallurgical technologies are being evaluated. Process Research ORTECH has developed a unique hydrometallurgical process to recover base metals and precious metals using mixed chloride technology. In a first stage leach, base metals are recovered and elemental sulfur is liberated from hydrogen sulfide formed during this leaching stage. During second stage leach, precious metals are recovered using proven separation technologies. Some of the advantages of the process are the recovery of elemental sulfur from sulfide sulfur, recycle of the chloride lixiviant thereby eliminating effluent treatment steps and use of excess energy from the Claus reactor for the pyrohydrolysis step.

Jan 1, 2011

By S. N. Monteiro, C. M. F. Vieira, M. M. Ribeiro

"This work has as its objective to evaluate the effect of incorporation of the powder waste retained in the eletrostatic precipitator of the sintering stage from an integrated steel making plant on the physical and mechanical properties of a red ceramic. Formulations were prepared with incorporation of the waste in amounts up to 20 wt.% into a kaolinitic clay. Rectangular specimens were prepared by uniaxial mold-press at 20 MPa and then fired at 750, 900 and 1050°C. The evaluated physical and mechanical properties were: linear shrinkage, water absorption and flexural rupture strength. The results showed that the waste has a potential to be used into red ceramics. The incorporation of the waste enhanced the properties of the ceramic, decreasing the water absorption and increasing the mechanical strength at all investigated temperatures.IntroductionThe sintering stage of an integrated steel-making plant is dedicated to the agglomeration of a mixture of iron ore, coke or coal, fluxes and water [1]. It is a common practice in this stage to use of solid wastes with great amounts of iron in the form of sludge and powder. One of the atmospheric pollutants generated during the sintering process is the particulate material, which is normally retained in an equipment denote as electrostatic precipitator. This equipment retains very small particulates, present in the gaseous emissions by application of an electrical potential difference in between the plates that the fluid is forced to go through. [2]."

Jan 1, 2011

By Wen Liangying, Zou Chong, Tan Xiuqin, Bai Chenguang, Zhang Shengfu

"Eight typical metallurgical byproducts containing iron were selected based on the effect of the chemical composition, particle size, additives on the burnout degree of pulverized coal. Effect of three typical byproducts including fine iron ore, BOF dust and BOF sludge on combustion reactivity and combustion efficiency were investigated using TG-DSC method. The results indicated that the three additives have obvious catalytic effects on pulverized coal. By comparison, the relative active sequence of byproducts to the catalytic combustion can be described as follows: BOF dust>BOF sludge>fine iron ore. Moreover, adding BOF dust as component of additives also shows significant catalytic effects on combustion efficiency during rapid heating process.IntroductionChina is the largest producer in the world with an annual output reaching over 6 billion tons. Solid wastes arising from iron and steel making increases the environment pressure in recently years. For instance, annual output of dust during the production of iron and steel making in China reach up to 5 million tons, which is close to 8%~15% of the amount of steel [1]. Another characteristic of these byproducts is they are finer particle which are just harder to deal with. Since some of solid wastes, including dusts, scales, and sludge, usually contain high iron content, sintering plants have traditionally been used to recycle byproducts in integrated steel plants in China. However these byproducts also have noticeable effects on sinter quality, sinter strength and productivity and, therefore, waste recycling is limited depending on the analysis of the waste materials [2]. Another method which is pre-treatment of byproducts in pelletizing process, increases of energy consumption and production cost. In addition, metallurgical byproducts often contain heavy metals and alkalis. For these reasons, recycling rate of the byproducts in China is very low. Therefore, how to recycle the byproducts in iron and steel making process is an important subject."

Jan 1, 2012

By Gerardo Fuentes

The stoichiometry and kinetics of the hydrothermal reaction of enargite in copper sulphate solutions was investigated in the range 140–300 °C, and particle size under 15 and 50 μm. The stoichiometric experiment was performed at 300 °C, using one gram of sample (96% enargite, 4% tennantite) and 100 mL of copper sulphate solution (10 gpl) at 1.2 pH. Enargite reacted completely after 80 min. A solid product was obtained and characterized by XRD. The main product was chalcocite (M) and some traces of djurleite and chalcocite (Q). Tennantite did not react under these conditions. The kinetic experiments were conducted at 140 °C, 190 °C, 250 °C and 300 °C. From fitted data and Arrhenius equation the calculated activation energy (Ea) was 51 kJ/mol. According to the hydrothermal transformations studied, the reactivity of different phases found in the copper concentrates was bornite > chalcopyrite > covellite > sphalerite > pyrite > enargite > tennantite.

By Donghai Li, Cheng Pan, Pan Chen, Xuewei Lv, Mei Liu

"Chromite concentrate after beneficiation can not be directly used in the electric furnace. Therefore sintering is one of the effective way to agglomeration, by which the chromite concentrate can be utilized and the power cost of ferrochrome smelting can be reduced. The properties of raw materials and the sintering process of chromite concentrate were studied in this work. The results showed that chromite concentrate used can hardly granulated alone, while chlorite addition can improve the effect of granulation. Moisture plays an important role in sintering process. The granulation effect is optimal when the amount of water addition is 12%. Strength and abrasion index are the evaluation indexes of sinter quality. It was found that the strength of sinter increased with coke dosage increasing to 12%, and then decreased when it continuously increased. Opposite regularities were found for the abrasion index of the sinter.1 IntroductionChromium is a very important metal element which is mostly used in the production of stainless steel. In the earth, it is always formed compound with iron as ferrochromium spinel (FeO.Cr203), and its mineralogical name is chromite.[1] Currently, the global production of chrome ore is about 20 million tonnage every year , in which fine ore (less than 8 mm) accounted for about 80% [2] Although the price of the fine ore is cheaper than the lump one, too much fines will lead to the poor permeability and causes increased electricity consumption while producing ferrochrome. Therefore, the agglomeration process of chrome ore is one of the effective measures to increase the usage ratio of fine ore."

Jan 1, 2013

By Yuan-bo Zhang, Gui-hong Han, Yan-fang Huang, Tao Jiang, Guang-hui Li

"Under isothermal conditions, the reduction behavior of oxidized pellets balled with bentonite was investigated with CO-CO2gas mixers in the temperature range from 900°C to 1100°C. The whole reduction of oxidized pellets was followed up by means of weight-loss technique. And the swelling index of pellets was examined by visualizing physical changes of pellet in a horizontal tube furnace. The results present that the reduction rate of oxidized pellets is increased with the increase of reduction temperature. While the swelling index is firstly increased and then decreased with the increase of reduction time and reduction extent, which can be ascribed to the disruptive stresses induced during the transformation of hematite to magnetite. The maximum swelling index is gradually increased with the increase of reduction temperature and CO content.IntroductionWith the rapidly development of iron and steel industry, direct reduction iron has been considered as one kind of high quality burdens in electric furnace steelmaking [1]. At present, ""Two-step"" coal-based direct reduction process, which employs oxidized pellets as raw materials, has been used in industrial production [2]. The reduction behavior of iron ore oxidized pellets has been becoming one of the most frequently studied topics in extractive metallurgy[3]. The heat and mass transfer in direct reduction processes results in a series of stepwise reduction reaction (hematite--magnetite--wustite--iron), accompany with the volumetric swelling of pellets[4]. A lot of literatures have been reported on the reduction model of ferrous oxides and swelling behavior of pellets. A. A. El-Geassy K, et.al [5-7] revealed that the reduction process was controlled by chemical reaction at early stage by employing pure Fe203 as raw materials and CO as reduction gas. Chen Y [8] made research on the reduction kinetics of porous oxidized pellets and obtained the rate constant and activation energy of at different reduction stage. In addition, the swelling and disintegration of iron ore pellets was affected by chemical composition of pellet and reducing parameters, which have been studied by numerous investigators [3,9, 1O]."

Jan 1, 2013

By J. Grogan

Leaching of galvanized steel coatings allows the steel substrate to be used as a zinc-free scrap source to steel and iron furnaces. In this study the behaviors of sulfuric acid leaching solutions are investigated. The ranked significance of the variables are shown to be acid concentration > temperature > zinc concentration. Examination of the leaching mechanism finds the rate-limiting step to be the cathodic hydrogen reduction reaction. This rate is not only influenced by acid concentration, but also by the hydrogen reduction exchange current density. Dezincing leaching rates are improved by taking advantage of the higher exchange current density of the iron substrate versus the zinc coating. This is accomplished in practice by increasing the exposed interfacial zinc:iron surface area through shredding. Also, a leach control mechanism is proposed through online monitoring of the zinc-iron couple mixed potential.

By Denise Cristina de O. Nascimento

Natural lignocellulosic fibers are increasingly being used as polymeric matrix composite reinforcement owing to economical and environmental advantages as renewable and biodegradable materials. Among these, the piassava fiber extracted from a palm tree native of South America stands as one of the most rigid with a potential to be used as composite reinforcement. Therefore, the present work investigates the notch toughness behavior, by Izod impact tests, of epoxy composites reinforced with up to 40 % in volume of continuous and aligned piassava fibers. It was found that the incorporation of piassava fibers results in significant increase in the impact energy of the composite. Scanning electron microscopy analysis showed that the nature of the piassava fiber interface with the epoxy matrix is the major responsible for the superior toughness of the composite.

Jan 1, 2009

By Hebi Yin

A coupled cellular automaton (CA) - finite element (FE) model was developed to calculate the growth of dendrites during the solidification of cubic and hexagonal metals. The model solves the conservation equations of mass, energy and solutes in order to calculate the temperature field, solute concentration and the growth morphology of dendrites, including the grain structure and the dendritic microstructure. Validation of the model was performed by comparing the simulation results with calculation results from previously published works, showing qualitatively good agreement in the dendritic morphology. Application to magnesium alloy AZ91 illustrates the difficulty of modeling dendrite growth in hexagonal systems, observed as deviations in growth direction caused by mesh-induced anisotropy. The model was applied to the simulation of small specimens with single- and multiple- equiaxed grain growths and columnar grain growth in directional solidification. The influence of cooling rate and some kinetics parameters on the grain morphology are also discussed.

Jan 1, 2009

By Artur R. P. Junior Sergio, Pedro A. Netto, N. Monteiro, Foluke S. de Assis, Frederico M. Margem

Synthetic fibers are being replaced gradually by natural materials such as lignocellulosic fibers. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as environmental and economic. So there is a growing international interest in the use of those fibers. The banana fiber presents significant properties to be studied, but until now few thermal properties on banana fiber as reinforcement of polyester matrix were performed. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity for polyester composites reinforced with banana fibers. In the polyester matrix will be added up to 30% in volume of continuous and aligned banana fibers. These values show that the incorporation of banana fibers in the polyester matrix changes its thermal properties.

Jan 1, 2015

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 Qiang Zhong, Qian Li, Yongbin Yang, Tao Jiang

Thermogravimetric analysis (TGA) has been used to research the pyrolysis and combustion processes of coal used in rotary kiln of iron ore oxide pellet. Furthermore, the effects of air flow and oxygen concentration on the combustion behavior of coal were examined with TGA. The results showed that two individual stages can be distinguished for the pyrolysis of coal, the water evaporation stage and the de-volatilization stage. And the information on ignition and burnout characteristics can be obtained from the combustion process analyzed by TGA. Large air flow almost has no effect to the combustion process except that it enhances combustion intensity. However, the combustion process is further accelerated under oxygen-enriched conditions. With all experimental results, it could provide an attractive approach of analyzing coal for the rotary kiln process.

Jan 1, 2016