Search Documents

By C. E. Abbey, M. S. Moats

It is well known that the addition of cobalt to copper sulfate — sulfuric acid electrolytes decreases the overpotential for oxygen evolution and decreases the rate of corrosion of Pb–Ca–Sn anodes. This effect, however, has not been ade- quately quanti fied in the presence of iron and manganese in this type of electrolyte. This work provides quanti fiable data on the effect of cobalt concentration in the range of 0 –0.6 g/L in synthetic electrowinning electrolytes with and without the presence of iron. The effect of cobalt on anode potential was determined using 2 and 24 h chronopotentiometry experiments. As expected, Pb–Ca–Sn potentials increased with decreasing cobalt concentration over the range of 0–0.6 g/L Co with and without the presence of Fe. Two regression models were developed to allow plant operations the ability to predict anode potentials as a function of cobalt concentration with or without iron in the electrolyte.

Mar 1, 2017

By B. M. Satish

The aim of the present work is to study the effect of annealing on the vibration damping capacity of high-chromium (16%) ferromagnetic steel. The alloys were prepared from raw materials of 99.9% purity melted in a high frequency induction furnace under high vacuum. The samples were heat-treated in vacuum at various temperatures (800 to 1200°C) for 1 hour followed by slow cooling (120°C/h). The inverted torsional pendulum method was used to evaluate the vibration damping capacity. The results indicated that the vibration damping capacity of the alloys is influenced by annealing and there exists a critical annealing temperature after 1000°C. The damping capacity increases quickly below the critical temperature since the magnetic domains move more easily.

Jan 1, 2009

By Jun Chang, Jin-hui Peng, Jing Chen, Li-bo Zhang

The leaching of indium from refractory zinc oxide flue dust(ZOFD) is attempted to utilize microwave sulfating roasting process, followed by water leaching. The ZOFD and roasted product were characterized by XRD and SEM/EDS analysis. The effects of various roasting parameters, such as roasting temperature/duration, the proportion of sulfuric acid, as well as the leaching parameters such as the leaching duration and liquid/solid ratio, were assessed. The results indicate that nearly 97% of indium could be leached under the following conditions: mass ratio of concentrated sulfuric acid to ZOFD to be 0.5, roasting temperature of 150 ℃ and duration of 1.5 hours; while the optimal leaching conditions hold at temperature of 25 ℃ for 1 hour, with 4:1 of liquid/solid ratio. The indium leaching rate by the microwave roasting increased by 8% as compared with the conventional roasting process under identical conditions.

Jan 1, 2015

By Marcos V. F. Fonseca, Djalma Souza, Luiz G. X. Borges, Sergio Monteiro, Caroline G. de Oliveira, Ygor M. de Moraes, Janine F. de Deus, Frederico M. Margem

Recently, the natural fibers have been studied as alternative reinforcement material to the use of synthetic fibers. Aiming to improve the properties of natural fibers composites, it is investigated the use of natural fibers fabrics, since they provide multidirectional reinforcement and enables the introduction of a larger fiber volume fraction. In this work, it was investigated the tensile behavior of the epoxy matrix composites reinforced with different volumefractions offabric made of Ramie, a highly resistant lignocellulosic fiber. The specimens were made by pressing the fabric with liquid resin to guarantee total impregnation, and then cutting the fabric in the mold format. Finally ,the fabric layers were placed into the mold with the liquid resin and catalyst. They were cured for 24 h and tested. The results revealed an increase in the tensile strength and almost no effect in the elastic modulus with the increase of fabric volume fraction.

Mar 1, 2017

By Xueming Lv, Xuewei Lv, Jie Qiu, Lunwei Wang

Non-isothermal multiple scanning rate analysis method was used to analyse the solid-state reduction of nickel laterite by carbon. According to the TG curves, the activation energies were calculated and the most probable mechanism functions were determined by the Malek method. The results show that the process can be divided into three stages according to the reaction degree (a): 0–40%, 40–70%, 70–100%, respectively. In the stage of 0 a 0.40, the most probable mechanism function fits the chemical reaction order function. In the stage of 0.40 a 0.70 and 0.70 a 1.0, the process may not be exactly described by one mechanism function.

Mar 1, 2017

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

By Xun Hu, Jian Pan, Hongbin Yu, Deqing Zhu, Yanhong Luo

Lump ores are one kind of important burdens for blast furnace (BF), their metallurgical properties have significant influence on BF performance. In this paper, the relationships between the mineralogy of five natural lump ores and the metallurgical performance have been studied. The mineralogy study includes mineral compositions, microstructure and porosity, and the metallurgical performance covers reducibility index (RI), low-temperature reduction degradation index (RDI) and decrepitation index (DI). The results show that the complex lump containing hematite, and goethite has better overall metallurgical performance. For single lump, the RI of goetihte ores is higher, the RDI and the DI is strongly influenced by porosity. The hematite and magnetite ores have good anti-decrepitation and anti-RDI, but generally the RI is lower due to lower porosity, and the RI is related to the grain size, the smaller grain size is, the better reduction will be.

Jan 1, 2015

By Lucio Fabio Cassiano Nascimento, Luis Henrique Leme Louro, Sérgio Neves Monteiro, Jheison Lopes dos Santos, Fernanda Santos da Luz, Fábio Oliveira Braga, Rubens Lincoln Santana Blazutti Marçal, Hugo Concolato de Oliveira Freitas, Édio Pereira Lima Júnior

Epoxy matrix composites reinforced with up to 10, 20 and 30 vol% of continuous and aligned natural mallow fibers and 30 vol% of mallow and jute hybrid fabric were for the first time ballistic tested as personal armor against class III 7.62 mm FMJ ammunition. The ballistic efficiency of these composites was assessed by measuring the dissipated energy and residual velocity after the bullet perforation. The results were compared with that in similar tests of aramid fabric (Kevlar™) commonly used in vests for personal protections. Visual inspection and scanning electron microscopy analysis of impact-fractured samples revealed failure mechanisms associated with fiber pullout, rupture and layers delamination. When compared to Kevlar™, the mallow fiber and hybrid fabric composite displayed practically the same ballistic efficiency. However, there is a reduction in both weight and cost, which makes both, mallow fiber and hybrid fabric composites, a promising material for personal ballistic protection.

Mar 1, 2018

By Ho-Sang Sohn

The kinetic study on desulfurization of copper matte by gas bubbling was designed under the presumptions of lower FeO activity and of no slag formation, Copper matte with 59% Cu and 22.6% S in weight was oxidized at 1523K by bubbling of Ar + O2 gas through a submerged nozzle. The effects of oxygen partial pressure and flow rate of gas on the oxidation rate of matte were discussed. The desulfurization rate and the evolution rate of SO2 gas of copper matte were significantly influenced by the oxygen partial pressure, but the dependence on gas flow rate was rather complicated. The desulfurization rate and evolution rate of SO2 gas of copper matte were described by the mass transfer rate through the gas film around the rising gas bubbles. Thermodynamic correlation equations between the partial pressure of gaseous species and matte composition were incorporated to the kinetic calculation, The present model shows that the reaction path starts to transiently cross over an isobar line of PSO2 to asymptotically approach to the particular isobar line drawn in a matte composition plane of %S and %O.

Jan 1, 2003

By Ryokichi Shimpo, Akio Fuwa

"In order to elucidate the present status of process-control technology, survey study has been made on the present process control schemes of representative copper smelting and converting processes in Japan. Conceptual control flow diagrams have been deduced and shown on respective functional reactors, i.e. drying, smelting, converting and fire-refining units, where the objective OUTPUT items are correlated to the INPUT variables through respective CAUSE-AND-EFFECT RELATIONSHIPSFuture view has been also discussed on several feasible and desirable improvement and refinement ~n measurements and control system for better copper smelting and converting operations.INTRODUCTIONIn other to seek for the better and efficient operation in copper smelting and converting process, survey study has been first conducted on the present process-control schemes of respective functional unit processes, i.e. drying, smelting, converting and refining unit processes, of representative copper production processes in Japan. Conceptual process flow chart of control scheme has been then deduced where output items are correlated to input items through the respective cause-and-effect relationships.After this survey study, future view has been discussed on the feasible and desirable improvement and refinement in the measurement and control system in these processes. Emphasis has been placed on the better and precise measurements of temperature, oxygen partial pressures in respective furnaces and end-point in converting and refining unit operations."

Jan 1, 1989

By Mim Li, Huimin Lu, Lisha Yang

"CuInS2 thin films solar cells have drawn much attention for their low-cost, stability and high conversion efficiency. The electrodeposition of Cu-In precursor films, as the first step in making CuinS2 solar cells electrochemically in the air-and water-stable ionic liquid based on choline chloride/urea eutectic mixture has been investigated at constant potential. Compared with aqueous electrolytes, the large electrochemical window as well as the high thermal stability of this ionic liquid allow the direct electrodeposition of Cu-In precursor films. Then the precursor films were sulfuretted in a tube furnace at different sulfurization temperatures to optimize the films properties. The films obtained were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS).IntroductionCuInS2 is one of the most prospective absorber materials for low cost thin film solar cells, with a high conversion efficiency that exceeds 32% in terms of theory and nearly 13% in laboratory level [1-2]. In addition to its long-term stability, CuinS2 has a band gap energy Eg ranging from 1.3 to 1.55 eV and an optimal optical absorption coefficient reaching 105cm-1 [3-4]. CuinS2 thin films have been prepared by several methods such as spray pyrolysis [5-6], r.f.sputtering [7], vacuum evaporation [8-9] and electrodeposition. Comparing with vacuum methods, electrodeposition has lots of advantages such as less energy consumption, preparation big area thin film, stable system and enabling cheaper films.The electrodeposition of most technologically important metals has been shown to be possible from a wide range of ionic liquids. These ionic liquids are currently applied in a wide variety area. It is reported that the cell efficiency of chalcopyrite absorber layer (CIS, CISeS, and CIGS) via an electrodeposition route in laboratory condition has reached 11.3% [10]. Copper and indium alloy film is regarded as important precursor for the production of compound semiconductors with sulfur. The electrodeposition of the alloy film from room temperature ionic liquid (RTIL) has not been widely investigated. Only few alloy films, such as ZnTe, CdTe, GaAs and AlSb have been electrodeposited."

Jan 1, 2011

By David R. Brosnahan

Increased Cu grades due to chalcopyrite-rich ore from The Doe Run Company's new Casteel Mine prompted a program to increase Cu recovery. Preliminary tests indicated that prohibitive quantities of FeS2 float with chalcopyrite. Point counting of mill stream samples showed that locking was not a major problem, although grinding to finer particle size enhanced the floatability of both chalcopyrite and marcasite. Backscattered electron images and microprobe analyses of FeSz minerals revealed the presence of Pb which appears to occur as solid solution in marcasite, and as a sub-micron particulate Pb phase in pyrite.

Jan 1, 1987

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 G. E. S. Lima, I. K. R. Andrade, N. G. Viana, R. O. G. Martins, L. M. Sathler, L. G. Pedroti, C. M. M. E. Torres, W. E. H. Fernandes, C. M. Silva, M. A. Caetano

In Brazil, kraft pulp mills are rapidly expanding and industrial waste generation is increasing. Technical feasibility of using solid wastes from kraft pulp mills as raw material in other industries may be an interesting approach to manage environmental and economic aspects of the industry. This paper proposes the incorporation, in different proportions (0, 2.5, 5 and 7.5%), of alkaline solid wastes from pulp mills, namely dregs and grits, to clinker in the Portland cement industry. The research was carried out in two steps: (i) characterization of dregs, grits and clinker; (ii) laboratory testing (determination of soundness by the Le Chatelier method, determination of setting times, determination of water content of the paste with normal consistency, determination of compressive strength and static modulus of elasticity). The results showed that the addition of dregs and grits to the clinker up to 2.5% were feasible according to the Portland cement Brazilian standards.

Mar 1, 2017

By Donggen Fang, Liu Xuan, Jilai Xue

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 NaAlSiO 4 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 Ying Wang, Min Chen, Cuihuan Huang, Haohua Deng, Nan Wang, Ming Chen

Adding limestone directly into converter is considered to be favorable to energy conservation and emission reduction by transferring the decomposition reaction of limestone from the shaft or rotary kiln to the converter. In this paper, the kinetics of limestone decomposing in early converter slag was studied at 1300–1400 °C, and the effects of slag temperature and stirring speed introduced to the slag bath were examined. The kinetic results based on shrinking core model analysis showed that the limestone decomposition was a mixed rate control of chemical reaction and heat conduction through the lime layer, which could be promoted at higher slag temperature by supplying more heat to the converter bath. In addition, the chemical reaction rate constant and effective thermal conductivity were determined.

Mar 1, 2018

By Shengli Tao, Hongxu Li, Hao Bai, Yu Chen, Daqiang Cang

"China is the world's largest steel producer, in order to give environment load comprehensive analysis of steel and iron industry in china using LCA method, the life cycle inventory was compiled and assessment model based on Gabi software was also established. Environmental impact of two different routes ofBF-BOF and the EAF were analyzed respectively and intercompared. The results show that the modem EAF route is superior to the traditional BFBOF route on almost all the environmental impact indexes, which including acidification potential, eutrification potential, global warming potential, ozone depletion potential, etc. In the whole life cycle ofBF-BOF route in China, the transporting process ranks the biggest contribution part to the overall global warming potential, which can be explained by the fossil fuel burning of transporting vehicles during the long distance from Australia to China as the iron ore used are mainly imported from Australia. Apart from transporting process, Coking, blast furnace and iron mining processes could induce great environmental problems, while for the EAF route, the electricity consumption is considerable, which causing large amount ofC02 emission indirectly. Based on the analysis, several further countermeasures were proposed. Key words: Iron and steel industry, LCA, Gabi software, C02 emissionIntroductionCrude steel of china which reached 101.24 million tons in 1999 ranked the first column in the world since1999, So far has been to keep the world's largest steel output. At the year of2009, China crude steel output of 568 million tons, accounting for 46.6% of the global crude steel production, more than the total sum of crude steel production produced by 20 countries ranked behind. In 2011, China's crude steel production which is expected to be or close to 700 million tons, an increase of 12% than last year, will account for half of the global steel production.The steel industry, however, is intensive resources industry with huge consumptions of energy and water together with mineral resources. Energy consumption of the iron and steel industry has been about 10% of the total energy consumption since 1980. Coal dominants, power next and other energies share least in the energy consumption structure, for example coal accounts for 72.19%, power 23.52% and other total sums less than 5% in the steel energy consumption at year of 2002[2,3]. The consumption of coal discharges much emission of CO2, yet emissions of C02 in China steel industry, secondary only to the power and cement industry, ranked the third, and the coal dominant energy structure and its process have a close relationship. The aim of this research is to target steel production of typical blast furnace-converter (BFBOF) and electric furnace, using GABI software to evaluate and analyze resources and environment influence of LCA, directing at the existing problems in the development of China steel as well as finding the possible way to improve ability of reducing pollution and energy consumption in order to realize the sustainable development of the steel industry [ 4-7]."

Jan 1, 2012

By Guohua Bai, Yuanbo Zhang, Guihong Han, Zijian Su, Daoyuan Zhang

"Specularite ores have poor hydrophilicity and ballability as well as inferior high-temperature reactivity, which restrict the large-scale application of them in the pelletizing and sintering production. Modified humic acid (MHA) organic binders are firstly used for pellet preparation from specularite in this paper. The results show that the drop strength of green pellets is 3.7 times/0.5m and compression strength is 12.5 N/P by using 1.0 wt% MHA as binder. Under the optimal experimental conditions of preheating temperature 980 °C, preheating time 12 min, roasting temperature 1280 °C and roasting time 10 min, the preheated pellets have the compression strength more than 400 N/P, and that of roasted pellets is 2747 N/P. The strength of finished pellets meets the requirements of blast furnace iron-making. MHA is a kind of more effective organic binder for specularite pellets compared with the inorganic bentonite.IntroductionAcid Pellets have advantages of good strength, uniformity particle size, high iron grade and good reducibility, which can be used as high-quality burdens for blast furnaces [1]. With fast development of Chinese iron and steel industry domestic magnetite concentrates with high grade of iron and good firing performances become shortage.Imported specularite ores have advantages of low price and high grade of iron (generally above 67 wt%), so the application of them in pellets is an effective way for sustainable development of pellet industry in China. However, the specularites have not been utilized in pelletizing and sintering at present because of the poor ballability and high-temperature reactivity [2, 3]. Most of the pellet plants use bentonite as binders, the amount of which is about 2~3 wt%. The pellet production practice shows that 90 wt% bentonite is still residual in finished pellets and reduces the iron grade [3]. Developing a new organic binder instead of bentonite is very important to the high-quality pellet production. On one hand, the consumption of bentonite is obviously reduced, resulting in decreasing the ironmaking coke ratio and slag discharge; On the other hand, the iron grade of finished pellets are improved, which brings the benefit for the ironmaking production."

Jan 1, 2011

By Lucas L. da Costa, Sergio N. Monteiro, Romulo L. Loiola, Tammy G. Rodrigues Portela

"The fibers extracted from the petiole of the buriti palm tree are relatively strong as compared to other lignocelluloses fibers, with a potential for composite reinforcement. In this work, polyester matrix composites incorporated with these fibers were investigated for their flexural behavior. Specimens with up to 40% in volume of continuous and aligned buriti petiole fibers were bendtested until rupture. The results showed an increase in both the composite mechanical strength and the stiffness with incorporation of these fibers. A fractograph analysis by SEM disclosed a moderate adhesion mechanism between the buriti petiole fiber and the polyester matrix. This mechanism is apparently responsible for the improved performance of the composites.IntroductionIn recent years, the substitution of energy-intensive synthetic materials for natural ones is being considered in many industrial sectors including automobile, packing and textile [1]. A typical case is that of natural fibers, mainly those obtained from cellulose-based plants also known as lignocelluloses fibers. They have being investigated in the past two decades, aiming to replace synthetic fibers, particularly the glass fiber, commonly used as polymer composite reinforcement [2-8]. From the engineering point of view, lignocellulosic fibers present today important environmental, economical, societal and technological advantages already discussed [7-8]. Moreover, several lignocellulosic fibers are known since the beginning of our civilization and still cultivated or naturally extracted all over temperate and tropical regions of the world. According to Kalia et al [1 ], these fibers can be classified by their origin, as shown in Table 1."

Jan 1, 2011

By Xiaolong Lin, Yuanbo Zhang, Guanghui Li, Zhizhong Li, Zhiwei Peng, Tao Jiang, Yan Zhang, Yutian Ma

Pyrometallurgical processes for recovering platinum group metals (PGMs) from spent catalyst have been the focus of current research for many years. They suffer from high energy consumption, large trapping agent consumption and huge slag production. Because of versatility of PGMs-containing spent catalysts, comprehensive recovery of valuable metals from these catalysts from an experimental point of view remains a challenge. In this study, thermodynamic analysis of pyrometallurgical smelting process in the presence of various additives for ef ficient recovery of PGMs was performed. It showed that addition of sodium salts would promote the migration and separation of the precious metals from carrier of the spent catalyst. By replacing calcium oxide with sodium carbonate and sodium borate, the smelting temperature could be reduced by more than 200 °C, which agreed well with the experimental findings.

Mar 1, 2018