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By Dai Yongnian

The methods of treating zinc crust and its development in the last hundred years are compared and reviewed. There are better effects from normal pressure metallurgy turned into vacuum metallurgy. The traditional methods dezinc only. But we must consider that delead on further step. From lab tests to industrial scale experiment are researched. The first step-dezinc, second-delead, crude ,metal of, zinc, lead and silver are produced, The flowsheet of treating zinc crust are simplified, material consumption reduced, work condition improved, environment protect mended. This method is pointed out that its application can be expanded.

Jan 1, 1992

By L. J. Cabri

The level of mineral exploration activity for platinum in recent years, especially in North America, has ranged widely. Exploration programs have been based on a variety of ore deposit models and deposit types. These range from the classic magmatic model for sulfide/oxide deposits and their associated placers, through hydrothennal models for bonanza-type deposits, to low-grade mineralization potentially amenable to lower cost bulk mining methods. The platinum-group element (PGE) distribution in these different deposit types is not well-known however, and PGE determination is fraught with analytical difficulties. To properly assess a prospect or to achieve effective recovery by mineral processing, it is important to determine the mineralogical distribution of the PGE.

Jan 1, 1988

By C. D. Mishra

The recycling potential for any gainful utilisation of the waste products is dictated by their quality, especially the chemical characterisation. The methods commonly used for the analysis of fly ash e.g. wet chemical, AAS, ICP-AES etc are time consuming. The paper describes a rapid XRF-based method for routine analysis of fly ash which involves preparation of local standards, optimisation of sample preparation technique and use of a simple PC-based software to account for interelement effects. The matrix corrected values are found to agree well with the wet chemical data.

Jan 1, 1992

By J. D. Sloop

This paper discusses the current state of EAF dust recycling at AmeriSteel's Dust Processing Division in Jackson, Tennessee. Included are a brief history of the plant, a description of the facility, a description of the process, and operating data.

Jan 1, 2000

By Laurence Whitty-Léveillé

Proper handling of the radioactive fraction associated with the production of rare earth elements (REEs) in the mining industry is essential for a sustainable environment and human health. Actinides, such as uranium and thorium, have similar chemical properties to REEs, and are often co-dissolved in current hydrometallurgical processes. This causes radioactive contamination of the infrastructure through the extraction cycle. The present study optimizes, through experimental design, a sequential leaching procedure with Na2CO3/NaHCO3 and HCl for the rapid and selective dissolution of REEs and actinides. Optimization focuses on the main operating parameters (time, temperature, and concentration); different types of minerals, REE composites, and ores; on achieving maximal leaching yield; and on minimizing dissolution of the gangue metals (Fe, Si, and Ca). The final sequential procedure was rapid (1 h), effective, and led to the segregation of Th, U, and REEs with limited dissolution of the gangue metals.

By Jinfu Xu, Youqing Cao, Yuting Lv, Hang You, Peng Jiang

"In present work, we reported the fabrication of composites consisted of M42 powder metallurgy high speed steel and 45 steel at one step via spark plasma sintering (SPS) technology. The interface microstructure, compositions and microhardness with the interface forming mechanism were investigated. The results show that the morphology and microhardness within the M42/45 steel interfaces exhibit a gradient distribution. The interfaces possessed a transition layer up to 10.2 ?m with few distortions and microcracks. The formation of M42/45 steel interfaces were driven by both fusion and diffusion processes. The former one was primary at the early sintering process, while the later one becomes dominant over the followed sintering process.IntroductionPowder high-speed steels have been widely used in cutting tools, cold-hot tools and dies, as well as in cut materials and structure parts with wear resistance and high-temperature resistance, due to its high hardness, good wear resistance, desirable cutting toughness and favorable hot hardness [1-2]. For materials of some parts in practical production, not only the favorable toughness is required to resist the impact action, but also the high hardness and exceptional wear resistance are demanded. According to the functional requirements and working conditions, bimetal composite materials are prepared in a certain mode, proportion and distribution, by designing two metals with different chemical and physical properties [3-6]. Considering the composites exhibit different properties in different positions of the parts with a combination of the advantages of two metals, they can obtain enhanced properties that the single one can not achieve."

Jan 1, 2012

By Sevinc Yildirim, Cigdem Oruclus

"Metal-Porous Silicon (PS) based structures dipped in water show the direct hydrogen fuel cell behavior. The effect of the thickness of the cupper (Cu) film on the electrical properties of direct hydrogen fuel cell is studied by fabricating Cu/Porous Silicon/n-Silicon/Indium structures. PS samples were produced electrochemical etching of n-type single crystalline silicon with a resistivity of 1,25 Ocm and (111) orientation. The thin films of Cu with different thickness between 200 and 600 nm were deposited on PS surface by electron-beam technique. Investigation of the effect of Cu layer on the performance of the structure indicates that the performance parameters such as open circuit voltage (Voc) and short circuit current (Isc) strongly depend on the Cu layer thickness. It was observed that the divice with an 350 nm Cu layer exhibits the highest open circuit voltage (0,5 V), short circuit current (0,01 mA) and power density (10 W.m-2).IntroductionHydrogen is the most attractive and ultimate candidate for a future fuel and an energy carrier. Hydrogen is recognized as the environmentally desirable clean fuel of the future since it can be used directly in different types of hydrogen fuel cells [1]. In the past years, the rise in portable electronics requires the development of miniature fuel cells compatible with standard silicon micro fabrication technology. Most silicon micro-fuel cells have used the polyperfluo-rosulfonic acid membranes (Nafion R) as a proton exchange membranes (PEM) that is not really integrated with standard micro fabrication techniques [2-5]. The composite materials such as inorganicorganic hybrid materials (Nafion-silica, Nafion-borosiloxane etc) are next generation of proton conducting membrane [4-8]. But, fuel cells run on pure hydrogen gas, which can be produced with other energy resources. Hydrogen smallest atom and thus the H2 gas can leak easiliy. The application of hydrogen for power sources has been greatly restrained due to the lack of safe and convenient generation and storage methods.A kind of hydrogen fuel cells Metal-PS-Si structures used as an energy water directly. There is no need pure hydrogen. Cu-PS-Si Schottky-type fuel cells with as proton-conducting membrane and the thin-film cupper catalist and water as fuel, which are interesting for fabrication of lowcost miniature fuel cells. Generation of the open-circuit voltage and short-circuit current has been observed by Cu-PS-Si structure dipping in different hydrogen-containing solution."

Jan 1, 2014

By Dieter Wanner

Off-gas cleaning from metallurgical? plants, requires in many cases very low dust contents which are, difficult to achieve with conventional scrubbers, even with high energy input. Lurgi has developed a scrubber which improves the separation of the fine dust by electrical charge prior to the scrubbing zone,, An Electrostatic Scrubber has been successfully installed for the off-gas cleaning from slag granulation after a waelz kiln achieving less than l mg/m3 in the clean gas.

Jan 1, 1992

By Fumito Tanaka

The Mitsubishi process is the sole pyrometallurgical process for the continuous production of blister copper from copper concentrates and has been successfully operated around the world. The development of calcium ferrite slag (CaO-FeOx-Cu20), the so-called "C-slag", has enabled continuous converting from matte to blister copper in the commercial scale operations. Commercial interests in the slag led to many papers over the CaO-FeOx slag. However, CU2O- bearing slag has not been studied well due to experimental difficulties. The authors have quantified the thermodynamic properties ofthe CaO-FeOx-Cu2O system. The results have been utilized to analyze various issues related to the converting furnace, such as the magnetite precipitation from the slag or from blister copper and to develop better controlling criteria for the continuous converting operation.

Jan 1, 2003

By H. Castillo

This paper describes the computer simulation of thermal stress fields generated in the quenching of the ns 415 H Steel automotive parts (Valve Lifters), running the ANSYS Multiphysics software of finite element (FEM). Simulation was performed introducing residual stress measurements on specific values areas, like internal pressure condition in the material. The stress condition effect in the material and the properties as temperature function data, were introduced to the FEM software. The thermal stress simulation was made on the 2D system. The parts were austenized to 850 900 °C and then oil quenched, tempered at 150 -200°C, and air cooled. The X-Ray diffraction technique was made to take measurements from residual stresses on valve lifters surfaces. The results analysis showed the ideal stress condition necessary in raw material to reduce the scrap percent in grind operations after hardening heat treating process. Keywords: Thermal Stresses, Temperature profile, Computer Simulation, Finite element analysis, Quenching of steel, Residual Stresses

Jan 1, 2003

By Zhijing Zhang

The management of hazardous wastes is important in a society which is increasingly concerned with environmental issues. Incinerators such as the slagging rotary kiln are widely used in the treatment of hazardous wastes. However, in order to assure a smooth operation of the rotary kiln, the melt should have both a low melting point and high fluidity. In this study, the fluidity of various hazardous waste rotary kiln slags was measured in terms of length of flow using the crucible test technique. It was found that the slags have melting points ranging from 1372 to 1424°C while their fluidities varied from 61-102 mm. The effect of addition of oxides on the fluidity of a slag containing 47 wt% SiO2 was also investigated. For this slag, additions of SiO2 (up to 56 wt%), FeO and Na20 increased fluidity, whereas the addition of CaO and A1203 resulted in lower fluidity values.

Jan 1, 2002

By Hui-Gai Li

The fine Ti oxide inclusions precipitated during solidification are favorable for intragranular ferrite nucleation. The oxygen content before solidification affects the composition and size of inclusions. The composition of precipitated inclusions in Mn-Ti alloyed steel was studied by means of thermodynamic calculation and experiment in this paper. The micro-segregation of Mn, Ti and O during solidification was considered in calculation and unidirectional solidification apparatus was employed in experiment to ensure that alloy elements diffused along solidification direction. The results showed that: inclusions are mainly Ti oxide when oxygen content is 10ppm; they are Ti oxide and Mn-Ti oxide when it is 20ppm; Mn-Ti oxide dominates when it is 30ppm. With the increase of oxygen content, the size of inclusions increases. The maximum oxides size is about 3µm from statistical results of experiment.

Jan 1, 2008

By Levente Becze

The zinc bottom dross is obtained as a by-product from hot dip galvanizing operations and contains at least 92 % zinc, which is recycled mainly by pyrometallurgical processes. The overall costs of such a treatment, however, are often relatively high, and the very strict environmental protection regulations might also cause additional difficulties for the high temperature procedures in the future. Therefore, a novel hydro-electrometallurgical process has been developed in our laboratory, by which one can reclaim zinc of high purity, while attempting to achieve low energy consumption and making allowances for all the environmental restrictions. This aqueous processing technique, based on electrolytic refining in a cell equipped with anion-exchange membrane to separate the anode and cathode compartments, allows the indirect purification of the anolyte. Zinc is dissolved from the anode along with some of the impurity elements, while the intermetallic compounds (Fe-Zn, Fe-AI- Zn) are accumulated in the anode slime.

Jan 1, 2003

By Tracy Lucas, Ian Hamill

"Issues of importance in the area of continuous casting centre around product quality. This can be affected by particle inclusions transported into the mould from upstream processes and by draw-down of particles from the meniscus. Turbulence of the meniscus can increase the latter and is also detrimental to product surface quality.Suitably validated Computational Fluid Dynamics (CFD) modelling can provide the operator with an efficient tool with which to investigate the effects of changes to the design and operation of the caster and associated plant.In this paper, examples are presented of the use of the CFD software, CFX, to simulate:•,free-surface shape and turbulence in the mould using deforming meshes•,solidification in the mould using a fixed-grid, source-based method•,argon gas injection through a submerged entry nozzle using a full multiphase model•,inclusion motion and removal in tundishes using an algebraic slip model.The CFD simulations of the free surface shape are complemented by detailed Particle Image Velocimetry measurements performed on a full-size water model of a thin-slab mould and upper strand. Close agreement is demonstrated between the predictions and experiments."

Jan 1, 1999

By Patricia Negrini Siqueira

Abstract. Polymers are susceptible to changes in their chemical structures that affect their mechanical properties under weather condition. Exposure of plastics to UV radiation causes a loss in their mechanical properties and/or change in appearance, including reduced ductility, color changes, yellowing and cracking. Today, there are several additive systems (light stabilizers) developed to work according to resin, final application, type of cultivation, and other characteristics. This study evaluates the different additive systems (Hindered Amine Light Stabilizer - HALS, nano calcium carbonate - NPCC, nZnO and nTiO2), applied 0.75% (in weight) in linear low density polyethylene (LLDPE). The samples were mixed by high rotation homogenizer and extrusion. Later, the samples were molded by injection and aged in QUV-B simulating 6 months of exposure to weather. Tests of FT-IR and tensile strength comparing to the non-aged samples were carried out in order to evaluate the performance of several additive systems.

Jan 1, 2015

By Katsunori Yamaguchi

A new technique for the removal of tramp-elements from steel scrap has been required from the viewpoint of saving energy and protection of environment. In order to obtain fundamental information on the removal of copper, tin and zinc from molten iron, the extraction method by using of phase separation in the liquid Fe-Pb-C system was investigated at 1453K. A mixture of iron, lead and carbon melted in a carbon crucible separates into two phases of lead and iron containing carbon. The compositions on the miscibility gap in the Fe-Pb-C system are 95.4%Fe-4.5%C-0.1 %Pb and 99.9%Pb-0.I%Fe. The distribution ratios of copper, tin and zinc between the lead and the iron phases, Lx [mass%X in molten Pb]/(mass%X in molten Fe), are 2.2, 2.2 and 1.4, respectively. Seventy percent of copper and tin from iron scrap can be eliminated with comparable lead addition. Gold, silver and palladium are enriched in the lead rich phase, on the contrary platinum and rhodium are more distributed to the iron rich phase than to the lead phase.

Jan 1, 2003

By Xu Zhang, Xuewei Lv, Guibao Qiu

Slag foaming phenomenon is of vital importance to the mass and energy transfer in metallurgical processes. A considerable extensively studies carried out via out-gas in the past cannot simulate well the foaming phenomenon formed in the blast furnace where high TiO2 iron ore is used. A gas reaction was designed in the water-glycerol system to simulate the inner-gas system. This study investigated the influences of solution viscosity, particle concentration and particle size on foaming caused by endogenetic gas. The results show that the foaming height decreases with the increase of solution viscosity, which means reduced foaming ability, more difficult foaming elimination process and prolonged time for natural defoaming. With increasing the solid particle content, the foam height presents a trend which increases firstly and then decreases. Under a certain solid particle content, foaming height decreases with the increase of solid particle size, indicating a weak foaming ability.

Jan 1, 2015

By D. G. C. Robertson

The thermodynamics and kinetics of the reactions involved in fuming zinc from oxide slags using coal or coke were first studied in 1955 and have been the subject of many investigations since that time. The key reaction is ZnO(in slag) + CO Zn(g) + COl. This paper will review the some of the recent work, and will add new insights obtained in experiments carried out by the authors. In the first series of experiments it was shown that the reaction 2Fe2+ + ZnO = 2Fe3+ + Zn(g) or 2FeO + ZnO = Fe2O3 + Zn(g) does not occur at an appreciable rate, as is expected from thermodynamic considerations. In the second series of experiments it was shown that zinc does not fume from the slag at a significant rate unless a reductant has been added. This again is in accord with thermodynamic considerations, but is in contradiction to some of the experimental results reported in the literature. A third series of experiments was carried out with excess coke being present, so that the rate of supply of reductant was not in any way controlling the rate. The kinetics of zinc oxide reaction were then found to be independent of the zinc oxide concentration, but increased with increasing basicity, and temperature. The presence of high concentrations of FeO in the slag also improves the kinetics. At low zinc oxide concentrations iron oxide reduction occurred in parallel with zinc oxide reduction. We propose that (under the conditions of this work) the kinetics were controlled by a chemical step, namely the rate of desorption of an adsorbed CO2 species. This is the same mechanism as reported by Belton and co-workers for the kinetics of the reduction of FeO. This explains why the reduction of metal oxides in slags by hydrogen is often faster than by CO.

Jan 1, 2003

By Bemd. E. Langner

At Norddeutsche AfFmerie the CollaMat is an important instrument for controlling the activity of glue in copper electrolyte. Thanks to on-line measuring of the glue activity appropriate action can to taken in the event of sudden changes, such as an intemption in the glue supply, as well as long-term trends, such as continuously decreasing glue activity over days or weeks. Laboratory tests on the dependence of glue degradation on temperature have shown that relatively small increases in temperature of only 3OC cause the half change value of the glue degradation to reduce by 25 %. It is a similar picture with the sulphuric acid concentration in electrolyte. An increase in the acid concentration from 160 g/l to 200 g/l can - depending on the temperature - likewise result in a decrease in the half change value of up to 25 %.

Jan 1, 1995

By K. Sanjay

Factorial optimisation technique has been used to develop regression equations at different time intervals for extraction of manganese from precipitated manganese oxide/hydroxide in sulphuric acid using charcoal as the reductant. The three parameters chosen for a 23 full factorial design were : acid concentration, amount of carbon and temperature. The regression equations were used to predict >> 90% extractions as well as kinetic data.

Jan 1, 1996