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By Jan Pan, Deqing Zhu, Xianlin Zhou, Yanhong Luo, Zixing Xue

"Magnetic roasting process, aiming at obtaining magnetite concentrate, is the principle method of exploiting siderite as a raw material in iron and steel industry. Study on preparing DRI from siderite through coal based reduction technology is sporadic. To make the process of how siderite is reduced to iron clear, roasted ore reduced from siderite by lignite under different time periods were analyzed. The results indicated that: at the temperature of 1050°C, siderite was rapidly decomposed into magnetite, and further reduced as Fe30r?FeO?Fe, the later step was slower than the previous one. A fracture of particles was found during the process of thermal decomposition and the reduction of newly formed magnetite. As the reduction proceeded, metallization rate of products increased, and the iron grain grew along with time.IntroductionWith the rapid development of economy, China demands more and more iron ores for the iron and steel industry. China has rich iron ore resources, but 97% of them are below 30% in iron grade, many are refractory and unutilized [1], therefore large quantities of imported iron ores are in a desperate need. China imported 686 million tons of iron ore in 2011 (data from the China Customs), accounting for nearly 60% of the total consumption. To guarantee the healthy development of iron and steel industry, domestic refractory iron ores have to be utilized both economically and environmentally."

Jan 1, 2013

By S. C. Flood, J. D. Hunt

"The columnar-equiaxed transition (CET) has been studied numerically under unsteady-state conditions using mathematical models that: (i) include a non-equilibrium undercooling at the columnar front;and(ii) describe the simultaneous evolution of the columnar and equiaxed zones.The results are discussed and compared with those produced by a steady-state analysis.IntroductionThe majority of the previous work on the columnar-equiaxed transition (CET) has concentrated on the production of equiaxed nuclei, regarding this as being the critical step in the formation of an equiaxed zone. Recently, the growth of equiaxed grains has been considered and this is not unreasonable because, for an equiaxed zone to be present, the grains must grow as well as nucleate. Since the growth rate of the grains will be determined by the thermal environment at and ahead of the columnar tips, it was decided to model the liberation and flow of heat during solidification to discover whether the various trends in the columnar range might be explained by their effect on the temperature profile throughout the casting. The models presented here for the solidification of a casting are the first to include the latent heat liberated ahead of the columnar front. Burden and Hunt (1) consider its effect only qualitatively, and although Lipton et al (2) adopt a criterion for the CET which is based on the thermal interaction of the columnar and equiaxed grains, they do not actually include the latent heat in their calculations.It can be argued that the latent heat liberated by the equiaxed grains in the bulk will retard the columnar dendrites in a casting: once the equiaxed grains are sufficiently well-established, the latent heat that they evolve could slow down the columnar growth to such an extent that the equi axed would dominate. Alternatively, the latent heat produced by the equiaxed grains might suppress further equiaxed solidification by raising the bulk temperature. The nature of the thermal interaction between columnar and equiaxed growth is not obvious, and because it is dependent on the material parameters and the dimensions of the system, it cannot be considered effectively in a qualitative way but has to be studied quantitatively: hence the need for the mathematical models discussed in the following pages. The results of the models are discussed in the light of a steady state analysis."

Jan 1, 1986

By Shoukun Wei, Cong Wang, Lin Cheng, Zhiyu Qiao, Jingkui Liang, Weidong Zhuang

"The subsolidus phase relations in the Sm2O3-CeO2-CuO ternary system sintered at 1000°C in air have been investigated by X-ray powder diffraction. The system can be divided into two ternary phase regions and three binary phase regions. Solid solution Sm2-xCexCuO4-y is the only ternary phase in the system. The maximum solid solubility was confirmed to be x = 0.2. The crystal structure, oxygen content and superconductivity of the solid solution Sm2-xCexCuO4-y have been investigated.I. INTRODUCTIONAfter the first discovery of the superconducting ceramic system La-Ba -Cu-O[l] with Tc = 30 to 40K, other families of cuprate-based ceramics have been synthesized with higher critical temperature. These oxides include the R-Ba-Cu-O (R: rare earth) systems (Tc=90K or so)[2,3], the Pb-Sr-(R,Ca)-Cu-O systems (T c = 50 to 100K), the Bi-Sr-Ca-Cu-O systems (Tc=80 to 105K)[4], the T1-Ba-Ca-Cu-O systems (Tc=85 to 125K)[5], the Hg-Ba-Ca-Cu-O systems (Tc=90 to 150K)[6,7], and some others. The improvement of Tc is very rapid. The measurement of the Hall and Seebeck coefficients shows that they all are p-type superconductors. In 1989, Tokura et al.[8] discovered the superconductors R2_XCexCU04_y(R = Nd, Pr, Sm) with Tc=20 to 24K (onset) and found that the charge carrier is electron in contrast to their hole doped counterparts. This discovery increases the fundamental understanding of the cuprate-based superconductors by comparing their characteristics and mechanisms to those of the p-type superconductors.One of the outstanding features of these n-type superconductors is the difficulty in obtaining samples in good charactors, such as the difficulty in obtaining zero resistivity state in single crystal or bulk samples; the semi-conductivity of bulk samples in ordinary state (opposite to the superconducting state) and a reducing reaction involved before the superconductivity has been found[9]. Therefore, it is necessary to optimize the sample preparation of the n-type superconductors. All the n-type superconductors have been found· considerable solid solubility. The compositional variations play a governing role in the carrier doping of the superconducting phases. Also, it is vital to the ceramic processing of superconductors to identify the compatible phases in the phase diagram. Finally, there is always the possibility of finding additional compounds, both superconducting and non-superconducting, in an unexplored system."

Jan 1, 1996

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 Jorge A. S. Tenorio, Chuanwei Zhuo, Joner O. Alves, Yiannis A. Levendis

"Reduction of combustion-emitted greenhouse gases, which are associated with global warming, may be achieved by use of CO2-neutral alternative fuels, such as bio-ethanol. Distillers Dried Grains with Solubles (DDGS) are the main co-products of the com-grain-based ethanol industries. In 2009, the North American production of ethanol from com was about 38 billion liters, which generated approximately 31.5 million tons of DDGS. Samples of DDGS were pyrolysed at temperatures of 600-1000 °C in a two-stage laminar-flow horizontal furnace, and a catalyst system was used to synthesize nanomaterials. This work presents a microstructural characterization of these nanomaterials by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results showed that the nanomaterials produced from pyrolysis of DDGS were in the form of long, entangled, rope-like structures with rugged walls, lengths in the tens of microns, and axially non-uniform diameters in the range of 100-300 nm.IntroductionThe interest in ethanol has increased considerably worldwide due to the necessity of finding renewable and cleaner energy resources [1, 2]. According to the Renewable Fuels Association (RF A), the world ethanol production in 2008 was approximately 65.7 billion liters (17.3 billion gallons), which figure represented a 24% increase in the production over that in the previous year [3]. The major producers of ethanol are the USA and Brazil, which together account for 90% of world production. The main feedstock for ethanol in USA is com grain, whereas sugarcane predominates in Brazil [2-4]."

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 Batric Pesic

The interactions of mineral-pyrite with T. ferrooxidans were studied by using a cyclic voltametry technique. The interactions with bacteria were examined during the entire growth stage of bacteria (fermentation), The pyrite ?surface invariably drastically changed ' its. properties at the second day of fermentation. Beyond two .. days of fermentation, the cyclic voltamograms were insensitive to convective diffusion produced by stirring. The product layer was examined by SEM,. X-ray diffraction and chemical analysis. The SEM study revealed that bacteria populated the pyrite surface at an extremely high density levels. The high density of bacteria, and the solid reaction products formed on the pyrite surface created conditions for pore diffusion which explained why the CVs became .insensitive to convective diffusion in solution (stirring). The x-r:ay diffraction study confirmed jarosite as a product layer. A mechanism of T. ferrooxidans cells serving as nucleation sites for jiarosite formation is proposed.

Jan 1, 1991

By M. Goto, T., Matsutani, T. Igarashi

"PT. Smelting was established in February 1996 as a company to· construct the first copper Smelter and Refinery in Indonesia with US$500 million direct construction cost and operate it. The plant is located in Gresik, East Java, Indonesia and 20km northwest from Surabaya, 2nd largest city in Indonesia. The site was selected due to following .advantages.1. Adjacent PT: Petrokimia Gresik, - a fertilizer company, purchases all sulfuric acid produced through pipeline.2. Facing on the seashore of the Madura Strait, it is possible to unload copper concentrate from West Papua (3,000km from Gresik) and load granulated slag to the market.3. Close to the good harbor facilities at Surabaya for export the products.4. Gresik Industrial Area has adequate infrastructure.5. Surabaya is a quite nice city to live for people from abroad.The shareholder of PT. Smelting are Mitsubishi Materials Corporation (60.5%), PT. Freeport Indonesia (25:0%), Mitsubishi Corporation (9.5%) and Nippon Mining and Metals Co. Ltd. (4.5%).The Gresik Copper Smelter and Refinery is designed to produce 200,000 tpy of copper cathode from 660,000 tpy of copper concentrates supplied 100% by 'Grasberg Mine of PT. Freeport, Indonesia in West Papua (former Irian Jaya). Other by products are 600,000 tpy of sulfuric acid, 30,000 tpy of gypsum, 509 tpy of precious metal slime and 400,000 tpy of granulated slag. These are sold to domestic and international markets.This project adopted the Mitsubishi Continuous Copper Smelting and Converting Process in the Smelter for anode casting, Contilanod process comprising Hazelett twin belt caster and a Mannesmann's travelling shear were selected. ISA stainless steel cathode process is applied in refinery. The combination of contilanod anode and stainless steel cathode ensured good cathode quality from the very beginning of start-up SO2 gas generated from Smelter is treated by Lurgi-Mitsubishi double contact/absorption acid plant. All contact. wastewater from the plant is treated in multistage wastewater treatment plant.Electricity and oxygen are ·supplied ""over the fence"" by a company which is located in the site of the Gresik Smelter and Refinery."

Jan 1, 2000

By James M. Fragomeni

"The mechanical behavior of an Al-Li alloy was studied and related to the extrusion processing parameters, the plastic metal flow during defonnation, the anisotropy, and the microstructure. The extrusion temperatures, strain rates, extrusion ratios, billet temperatures, and extrusion geometries were varied during processing and correlated with the microstructure and properties. The extrusion processing variables were related to the mechariicar behavior, anisotropy, and microstructure through the ZenerHollomon parameter i.e., the temperature compensated strain rate. Based on optical and electron microscopy studies it was found that regardless of the extrusion conditions, the various microstructures for the most part were unrecrystallized for both the as-extruded and the solution heat-treated conditions. Smaller grain sizes were correlated to larger Zener-Hollomon parameters. The extrusion temperature and ratio did not significantly affect the strength or ductility as did the section geometry, which had a large affect on these mechanical properties. The anisotropy of the properties varied substantially when comparing the extruded longitudinal versus transverse grain orientations.IntroductionThe extrusion process also has a substantial influence on: the microsfructure and mechanical properties of a material that is Athens, Ohio, 45701 fonned The plastic defonnation that occurs during the extrusion process alters the grain size, crystallographic texture, anisotropy, subgrain size, dislocation density and various other microstructural features. Often the material being extruded is not homogeneous, therefore variations in the microstructure and properties occur across the cross-section of the final extruded product. The mechanical properties and microstructure can also vary with length since it is hard to maintain a constant temperature throughout the extrusion process. The extrusion temperature often varies from the heat generated during the extrusion process. The demonstration material that was extruded for this .study was an aluminum alloy containing 2.6wt, % lithium and 0.09wt.% zirconium. This alloy was strengthened by heat treatment causing nucleation, growth, and coarsening of coherent metastable o' (Al3Li) precipitates in the microstructure. The ? precipitates which are a consequence 9f artificially aging the AlLi alloy, are spherical, ordered, and coherent with the aluminum matrix and impede the dislocation glide inotion during plastic defonnation. Theo particles grow homogeneously in the matrix, and have the Cu3Au (L 12)"" superlattice crystal structure. Aluminum-lithium alloys are used primarily for aerospace structural applications since they have attractive properties such as a lower density and higher elastic modulus than conventional 2XXX and 7XXX alloys."

Jan 1, 2000

By Philip Arthur

The ISASMELT process is making a significant contribution to the global metals industry. ISASMELT furnaces are now operating successfully in eight different countries and treating approximately 3 million tonnes of concentrates and secondary materials per year. The process is currently used in both lead and copper smelting. The most recently commissioned plants were in Germany and China, one for treating scrap copper and the other treating low-grade copper concentrates. The Copper ISASMEL T furnace ("CIF") at Mount Isa Mines Limited (UMIM") has continued to set new operational records, with throughput of more than I million tonnes of concentrate per year and very low operating costs. This paper summarises the latest operational data from the Mount Isa Copper ISASMEL T plant and outlines the successful approach to industrial R&D taken by MIM in the development of the ISASMEL T process.

Jan 1, 2003

By Michael L. Sorokin

The various methods of converter slag cleaning operation are analysed from the thermodynamk point of view: cleaning using coal, cleaning using combustion products of natural gas and cleaning in presence of matte. All calculations were done, applying the developing computer procedure based on the free energy minimisation algorithm. Three-suffix Margules equations were used to calculate thermodynamic properties of melts; The calculations resulted in recommendations for the practical appliance.

Jan 1, 1995

By Charles H. Buclmam

"Environmental regulatory requirements for discharge of solutions and closure of operations for the gold mineral processing industry have been gradually lowered and in certain instances have been targeted to USEP A inorganic drinking water standards for dissolved ions in solution. The use of jar tests for water treatment process development is suitable for preliminary scoping work to be conducted in the research laboratory, as well as for optimization studies at the site of the treatment requirement. This paper will describe experimental methods which were performed using standard jar test equipment in efforts to produce solutions which meet USEP A inorganic drinking water standards after chemical treatment of cyanide solutions. The materials tested included gold bearing pregnant solutions from heap leaching operations, gold plant barren solutions from the Merrill-Crowe zinc cementation gold recovery process and gold heap leach wash solutions after carbon-in-column gold recovery. Experiments included cyanide destruction with sodium hypochlorite and arsenic and selenium co-precipitation coupled with mercury precipitation.IntroductionCyanide leaching solutions are used to selectively dissolve metallic gold from commercially viable mineral deposits. The heap leaching process involves stacking of gold bearing ores on specially designed solution containment pads and percolating alkaline cyanide solutions through the ore to dissolve the gold. Pregnant solutions containing the dissolved gold are collected and sent through a gold recovery process. After selective recovery of the gold, the barren solutions are recycled to the gold extraction process after adjustment of the solution alkalinity and available cyanide concentrations."

Jan 1, 1997

By Zhihua Wang

Through metallurgical calculation and process analysis based on metallurgical theory, it is aimed to raise the concentration of smelting oxygen and improve the update speed of reaction interface, accelerate the reaction and achieve a high-intensity smelting at the stage of converting. The PM plant has launched a theoretical research on model of high-intensity converting aiming at increasing the oxygen concentration of converting, carried out transformation of Kaldo furnace converting system, performed a series of industrial trial operations, conducted multiple rounds of tracking test and data comparison in reducing the furnace cycle, lowering the unit consumption of fuel and stabilizing the furnace lining life. The move has practically tested and verified the correctness of high-intensity smelting theory.

By Rafael Colás

Computer visualization can be employed in industry as an aid to the understanding of the complex interactions between variables encountered in production. The examples of ingot casting of rimming steel and that of hot rolling of low carbon steel strip are presented. Both processes are mathematically modeled, and their results are presented in a graphical way. Such models have been proven to be an asset in quality improvements and increase of productivity as the personnel involved get a better understanding of their job.

Jan 1, 1993

By Y. Suzuki, J. Nagao, Y. Ueda, K. Shimokawa

"A Ti- Ni intermetallic compound could be formed rapidly from Ti and Ni powder compact with SHS process. Microgravity experiments using a drop shaft are carried out, This report shows the effect of microgravity or high gravity on formability of an intermetallic compound. It is concluded that the specimen forms a porous and nearly amorphous alloy by rapid cooling under microgravity but with rapid cooling under high gravity after microgravity, the specimen forms a uniform and dense structure with better crystallinity.IntroductionTi - Ni inter1etallic co1pounds have been produced and have beco1e si1ilar to the a1orphous and porous structure as a result of the SHS (Self Propagating High-te1perature Synthesis) process under 1icrogravity. SHS process is being applied to the synthesis of cera1ics and inter1etallic co1pounds (1). The technique is characterized by a large a1ount of heat being emitted within a very short ti1e interval as regards the sistering reaction. One SHS process, acco1panying 1elting by a reaction was observed, and that was due to the quick heating of a Ni-Ti co1pact containing 50 ato1ic percent of Ti under a low pressure (2-4). In this report, we have researched the use a drop shaft which is 1ore effective during a short ti1e under 1icrogravity and high-gravity, so as to obtain high dense speci1ens with the exception of porous specimens (5). Mechanical properties of each specimen were esti1ated from these 1icro-structures with a discussion about the effect of changing gravity regarding 1elting and solidification of the Ti-Ni intermetallic comounds."

Jan 1, 1996

By Norihiro Murayama

Syntheses of zeolitic materials were carried out from coal fly ash by alkali hydrothermal treatment as part of the reuse and recycle technologies of coal ash, For the obtained zeolites, the cation exchange capacity and acid resistance, which are very important in the practical use of cation exchanger in aqueous solution, are investigated during this stufY, The cation exchange amounts of the NaP, CaP and K-CHA zeolites are measured for various cations such as K+, Na +, NH4+ Ca2+, Mg2+, Pb2+, Cd2+ and so on. The change in crystallization degree are researched as a function of pH. The simultaneous removal ability of NH4+ and PO43- in solution is examined for an example of the water purification with CaP zeolite. From these results, the characteristic and its mechanism of cation exchange are clarified for the various zeolitic materials obtained from coal fly ash.

Jan 1, 2003

By D. J. Murdock

Cominco Ltd. has developed a number of innovative technologies for electrowinning. The paper discusses the application of these technologies to the copper industry. Tankhouse and cell design will be discussed in addition to anode cleaning and cathode handling. Specific examples of the application of this technology to the copper industry are cited.

Jan 1, 1987

By G. Diáz

A basic technology coping with a wide range of secondary zinc sources has been developed. The process combines an electrowinning stage, a solvent-extraction unit and a leaching procedure. The acidity generated in zinc electrowinning, transferred by the organic solvent to the aqueous raffinate, is reused to leach the zinc secondary materials. The basic process recovering zinc is described in detail. The route recovering other valuable metals such as copper, cadmium and lead associated with zinc is also described. This non-ferrous metals recovery route is advisable for either ecological and/or economical reasons. Main results of an experimental program aiming at the demonstration of the suitability of the process for several feed materials are summarized. Waelz oxides, galvanizing ashes and EAFD coming from different sources were tested in laboratory and continuous pilot plant campaigns. High zinc recovery, low reagents and utilities consumption, and effluents meeting environmental regulation were confirmed. The paper also includes the main results of a feasibility study of an industrial "base case". A mixed raw material and Spanish EAFD and 20,000 ta of zinc ingots production were chosen. The SGH zinc recovery from secondary raw material by means of the clean, safe and profitable Modified Zincex Process has been demonstrated. This reliable technology is ready for industrial application.

Jan 1, 1995

By Uchil Jayagopal, P. V. Krupakara, S. Manjunath

"This paper deals with the corrosion characterization of quartz particlate ZA-27 alloy metal matrix composites (MMCs). Quartz particles of size 50-80 microns are used as reinforcement. MMC's are prepared according to ASTM standards. Composites containing. 2, 4, and -6% by weight of quartz and unreinforced matrix were tested using 1 -N hydrochloric acid: The composite was found to be more corrosive resistant than matrix alloy. In each test the corrosion resistance of both alloy and composites were found to decrease with the exposure time.1. IntroductionMetal matrix composites- (MMCs) offer designers many added benefits, as they are particularly suited for applications requiring good strength at high temperature, good structural rigidity, dimensional stability, and light weight 1-5. The trend is towards safe usage of the MMC parts in the automobile engine, which work particularly at high temperature and pressure environments Particles reinforced MMCs has been the most popular over the last two decades.ZA alloy MMCs have most popular families being represented by. ZA-27 alloy reinforced with ceramic particulate. Although the incorporation of the second phase into a matrix material can enhance the physical and mechanical properties of the base metal, it could also significantly change the corrosion behavior.ZA alloys have been used extensively in industry. This is attributed to their excellent fludity, castability and good mechanical properties. Among the zinc-based foundry alloys, the ZA family of alloy have been widely used during the past few years. ZA alloys have many advantage over aluminium based ones, especially high strength with a low casting temperature 8."

Jan 1, 2000

By Dimitrios Fillippou

Magnesium hydroxide is used in a number of industrial applications, from the neutralisation of acid effluents to the production of pharmaceuticals. High-quality magnesium hydroxide powders can be produced by hydrating slow-reacting magnesia in dilute magnesium acetate solutions. The process of magnesia hydration shows many similarities with a typical hydrometallurgical leaching operation; however, its kinetics are crucial not only for process design and control, but also for the production of powders with a desirable particle morphology. This article shows the results of an experimental work whereby industrial heavily-burned magnesia powders were hydrated in 0.01 to 0.1 mol/L magnesium acetate solutions at temperatures ranging between 333 and 363 K. Examination of the magnesium hydroxide produced and the analysis of the kinetic data suggest that the hydration of heavily-burned magnesia in magnesium acetate solutions is a dissolution-precipitation process controlled by the dissolution of magnesia particles. The activation energy was estimated to be 60 kJ/mol, while the reaction order with respect to magnesium acetate concentration was found to be about one.

Jan 1, 1999