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By M. I. Kalashnikova

Results of investigations concerning precipitation of heavy non-ferrous metals from solutions using precipitators based on elemental sulphur and lime with gypsum transfer to a separate product are given.

Jan 1, 2003

By C. Ek

In bismuth metallurgy, low-copper high-sodium mattes are by-produced. Different charges containing mixtures- of crude mattes, oxidized matte, and/or copper sulfide concentrate and/or copper silicate ore have been smelted to give a rich matte and a disposable slag, then converted to obtain blister copper with high recovery and a rich slag to be recycled.

Jan 1, 1983

By V. M. Paretsky

The basic work conducted by Prof. A.Yazawa has demonstrated that in order to ensure single- stage white metal production by autogenous smelting of copper sulfide raw materials, it is most favorable to use highly basic slags, in particular oxide systems CaO-FeO-Fe2O3-SiO2. The special studies have been conducted in the Gintsvetrnet Institute to investigate the composition and structure of slags produced on a semi-commercial scale when testing the KFP and FBP processes for white metal smelting. as well as the slag obtained in a full-scale KFP furnace at the Almalyk copper smelter. The investigations conducted have demonstrated why production of high-grade matte or white metal is associated with lower loss of copper in slag in a series: silicate slag I silicate-calcium slag I ferrite-calcium slag.

Jan 1, 2003

By J. B. See

Emeritus Professor David Robertson of the Missouri University of Science and Technology was born in Dublin Ireland on 29 December 1941. His father was a merchant navy Captain who served during WWII and during David’s early years his family lived in Dublin and Donegal where David went to the local elementary school. In 1954 he moved to London with his parents and attended Highgate School before commencing metallurgy at the Royal School of Mines, Imperial College, London in 1960.

Jan 1, 2014

By F. Garcia-Carcedo

This research aimed to develop a clean technology for the production of ZnO from residues generated by the steel making industry. Scientific and technologic parameters were both investigated in order to define an industrial methodology allowing the integral recycling of EAF dusts. A reengineering of the Waelz process was perform,~d, aiming to produce a clean fraction of ZnO, fluorine free, as well as a slag enriched in metallic iron, which can be recycled in electric arc furnaces. The technical conditions used to produce the ultra pure fraction of ZnO are described. The magnetic separation of the EAF dust allowing the production of a phase high in iron and recyclable to the electric arc furnace is also discussed. Thermodynamic of the volatilization of all the elements contained in the EAF dust was performed in order to better control the thermal process in the rotary kiln. Tests were run using different reducing agents, weakly or highly reactive, aiming to determine their specific efficiency.

Jan 1, 2000

By Hani Henein

Recent innovations in atomization of molten metals have occurred in the area of single fluid atomization. Impulse Atomization (IA), one of the single fluid techniques, provides unique capabilities to study different regimes of atomization in a controlled environment. By changing processing variables, a mono-dispersed distribution of droplets above one millimeter in diameter can be produced. This is accomplished through proper characterization of the forces influencing the process and in particular the flow of melt through the orifice. This paper will discuss the approach and illustrate results with molten aluminum and cobalt.

Jan 1, 2006

By Sanaz Mosadeghsedghi

The feasibility of the application of electrodialysis in separation of light and heavy rare earth elements (REE) in synthetic solutions was investigated. The experiments were carried out using single and binary solutions of a light (cerium) and heavy (ytterbium) REE. The effects of electrical voltage, electrical current, and the addition of complexing agent (EDTA) to increase the separation selectivity were investigated. Separation of Ce and Yb was achieved in binary solutions with and without the addition of EDTA. Higher degrees of separation were seen at higher voltages. Ce–Yb separation was more significant in the presence of EDTA. The separation factor of Ce–Yb and Ce–Yb-EDTA were 1.44 and 2.60, respectively.

By Claudia Gasparrini

Uranium occurs in a variety of minerals, the more common primary ones of which are uraninite-pitchblende, coffinite and a group known as the complex multiple oxides. Identification and description of the uranium-bearing and associated minerals in ore samples may give a preliminary indication of the potential economic importance of the deposit and may also suggest initial approaches to metal extraction. The present paper reviews the common uranium minerals, describes their manner of occurrence and compares the types of deposits with which they are associated. Methods and techniques for their identification are described and their leaching characteristics discussed.

Jan 1, 1981

By Zhigang Liang

Effects of the configuration parameters of submerged entry nozzle on the flow field in slab mold were investigated through a water modeling. The experimental results showed, when the original submerged entry nozzle was applied, there was an appreciable level fluctuation in the mold with obviously naked surface and entrapment of mold flux at higher casting speed. By increasing the outlet area of submerged entry nozzle, without any change of other configuration parameters and submergence depth, a proper fluid field with active surface and good covering of mold flux can be obtained, which is proper to meet the requirement for increasing the casting speed and improving the slab quality simultaneously.

Jan 1, 2009

By Z. Jing, L. Qihou, C. Jun, L. Hui, Z. Yumeng

Three phases of Bi2O3 were first synthesized by extraction-stripping precipitation and post decomposition from BiCl3 leaching solution. The as-prepared Bi2O3 were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning and transmission electron microscopy (SEM, TEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), Brunauer-Emmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS). The photocatalytic performances of the oxides were investigated by decomposing rhodamine B (RB) under visible irradiation. It shows that the Bi2O3 with different crystal structures and morphology were obtained under different decomposition temperature. The band gaps of as-prepared samples were 2.36, 2.41, and 2.78 eV for b-Bi2O3, a-Bi2O3, and d-Bi2O3, respectively, and the photocatalytic activities followed the order: b-Bi2O3 > a-Bi2O3 > d-Bi2O3, which was in good accordance with the photoluminescence spectra measurement results. The b-Bi2O3 exhibited the best photocatalytic performance which can effectively degrade 99.23% RB within 240 min.

Mar 1, 2018

By T. T. Nguyen, D. R. Gunasegaram, D. Celentano

"Heat transfer rates at the casting-mold interface are believed to be substantially reduced by the formation of an interfacial gap during the course of solidification of aluminum alloys in permanent molds. In the current work, the effect of force-cooling a permanent composite mold on (i) the initiation and growth characteristics of the gap and (ii) interfacial heat transfer rates are studied. Interesting comparisons are made with the case where no cooling is employed. Casting and mold displacements are measured using L VDTs, and the mold is force-cooled by air jets.IntroductionIn a gravity casting situation where an aluminum alloy solidifies in a permanent mold, a gap initiates and grows between the shrinking casting and the expanding mold (1). It is widely believed that the formation of this gap, customarily referred to as an 'air gap', results in a substantial reduction in the heat transfer coefficient at the casting-mold interface (2), and hence is an important factor in solidification studies.The nature of the air gap formation process is thermo-mechanical. The rate of heat loss from the casting first determines the rate of solidification, which, in turn, decides when the gap initiates. The reason for this is the requirement for the solidified casting surface 'skin' to gain sufficient thickness, and hence strength, to be self-supporting. Once the gap initiates, the gap width controls the rate of heat loss from the casting, which, again, determines the rate at which the gap expands."

Jan 1, 1997

By B. Q. Li, S. P. Song

"Numerical models are developed to represent complex electromagnetic, free surface deformation and fluid flow phenomena in floating zone refining processes with radio frequency inductive heating. The computational methodology is based on the coupled finite/boundary element method for the electromagnetic field distribution and the Galerkin finite element method for magnetically driven fluid flow and free surface profiles of the molten zone. With the models, the complex transport and free surface phenomena in a floating zone system can be studied as a function of various operating conditions including applied current, frequency, inductor position and shape, surface tension, floating zone diameter and height. Results show that the equilibrium shape is sensitive to the height of the molten zone and that the free surface shapes can have a significant effect on the melt flow in the molten zone. Our extensive simulations also suggest that to ensure accurate results, the same mesh should be used, whenever possible, for both the electromagnetic forces and fluid flow calculations.1. IntroductionThe floating zone processes have been widely used in the materials industry to grow ultra-pure rare earth metal or semiconductor single crystals for sensor or electronic applications that have a tough demand on purity. Developed based on the principle of magnetic melting/levitation, the processes possess a main advantage that the molten zone is supported in air by the electromagnetic forces generated by the coil (see Figure 1), and therefore is free from contamination from a container. Consequently, the final products made from the floating zone processes have higher inherent purity than those by other techniques [1-4].Complex physical phenomena occur in the floating zone processing of materials. These include free surface deformation, magnetically-driven melt flow, which may be turbulent or mildly turbulent [5] depending on the applied conditions, and solidification. Thermal stresses also develop in the single crystals, which are affected by the flow and temperature field and which can have direct implications to qualities of single crystals [6]. An understanding of the fundamentals governing these physical phenomena can be of critical value in elucidating the physics that controls the properties of the metal or semiconductor crystals being produced, thereby providing a rational basis for process improvement and quality control."

Jan 1, 1997

By Neil Smith

Mineral processing plants typically procure a range of industrial services from contractors. Their satisfaction and value received is directly affected by how the services are procured, rationalized and delivered. Conventional purchasing strategies often focus on price rather than on optimizing the service relationship between supplier and customer. The nature of this relationship may have the greatest potential to reduce costs and enhance production. It has been documented that a service involves simultaneous production and consumption. A high degree of customer involvement is often necessary for a successful outcome and the expectations and attitudes of the customer can positively or negatively affect delivery of the service. This indicates that the customer can enhance or diminish their own satisfaction and value received and the supplier cannot act alone for best results. The Optimax? Program for industrial services is a service delivery framework whereby a customer and supplier work together to raise the efficiency of the service exchange. The Optimax? Program is intended to help the customer optimize costs and maximize production by connecting the customer and supplier through shared information and objectives. This paper will review the basic nature of services, provide a couple of examples of conventional procurement strategies for services and outline the features of the Optimax? Program. A Case Study showing recent results from implementing the Optimax? Program will be included.

Jan 1, 2006

By Mei Song, Qingyu Deng, Xuewei Lv, Lu Liu, Chenguang Bai, Meilong Hu

"The carbochlorination of several silica materials was carried out in the temperature range from 900 °C to 1200 °C. In this study, silica oxides and gaseous chlorine with carbon as reductant were used. The optimal carbon silica mole ratio in different temperature was calculated by Factsage software and the results showed that the optimal values are 1.2, 1.4, 1.6, 1.8 at 900 °C, 1000 °C, 1100 °C, 1200 °C, respectively. According to the experiments, the chlorination ratios of several silica materials were increased with temperature increasing. In the same temperature, the chlorination ratio of diatomite is the maximum and the chlorination ratio reaches 79%% when C/SiO2 reaches 3 at 1100 °C.1, IntroductionPolycrystalline silicon is the main material to manufacture the silicon polished section, solar battery[1] and high purity silicon wafers[2], also which is the most basic function material of semi-conductor industry, electronic information industry and solar photovoltaic battery industry[3]. The conventional manufacturing process of polycrystalline silicon would be divided into three parts: the improved Siemens method, which was introduced and became the main process to produce the polysilicon products in China. Silane method and fluidized bed method. Silicon tetrachloride and chlorosilans have been employed as by-products in several fields like electronic, telecounications and metallurgy[4-6]• At present, the main applications of silicon tetrachloride include production of trichlorosilane by catalytic hydrogenation, synthesis of fumed silica and ethyl orthosilicate, production of optical fiber grade silicon tetrachloride.The conventional routes for the silicon tetrachloride production have been reported, including the direct chlorination and the chlorination process of ferrosilicon, abandon catalyst and silica[7]."

Jan 1, 2013

By F. Z. Utyashev

The present work considers the essence of fragmentation: on the level of a simple model as a material response to the curvature accumulated by it at large deformations. It is on this basis that the correlation between curvature and fragment sizes is determined. It is shown that at deformation the area of curvature center inevitably changes. It is revealed that a specific value of variation of center surface area, i.e. ^As parameter, is numerically equal to the value of curvature acquired by a material. Minimum sizes of fragments and grains depending on ^As have been estimated, and the dependence of this parameter on strain has been established. Besides, the present paper considers the effects exerted by curvature center geometry, material distortion, directions of deformation and thermal warming up in the localization zones on structure refinement when various techniques are applied.

Jan 1, 2006

By Ann M. Hagni

Electric arc furnace (EAF) dust from the secondary steel industry contains lead, cadmium, and chromium that causes it to be classified as a hazardous waste. Pyrometallurgical treatment of EAF dust is directed at recovering zinc and simultaneously rendering the dust non-hazardous. The mineralogy of the EAF dust is important in determining the occurrence and phase relationships of the zinc, lead, cadmium, and chromium contents. The principle phases in EAF dust as determined by reflected light microscopy, SEM-EDS, and XRD are solid solutions of the iron spinels (franklinite, magnetite, and jacobsite), zincite, hematite, and Ca-Fe-Si glass. Chromium is present in small amounts in solid solution in the spinels. Cyclone sizing of the minus 53 pm particles shows that more than 50% of this size fraction are less than 10 pm in diameter. The <I0 pm particles contain zinc as both franklinite in solid solution with magnetite and jacobsite, and zincite as determined by transmission electron microscopy and XRD. Auger electron spectroscopy did not detect coatings of volatile phases on the surfaces of EAF dust particles.

Jan 1, 1994

By O. M. Popoola, A. P. I. Popoola, D. O. Okanigbe, A. A. Adeleke

The physical, chemical, mineralogical and morphological characteristic of the waste copper smelter dust (CSD) from Palabora Copper (PTY), Limpopo, South Africa, has been reported in the open literature. The bulk of this material falls within the −53 μm particle size fraction with a copper weight percent of 18.02 as determined with the XRF. The high presence of reactive gangue minerals such as mullite (42.97 wt%) and quartz (11.45 wt%) necessitates that the waste CSD be first upgraded of its copper value in the falcon gravity concentrator before subsequent hydrometallurgical treatment. As an initial step, a sample preparation was carried out to make the sample amenable to both real density determination and copper upgrade experiment, thus resulting in 97% of the particles passing the 300 μm sieve aperture (d97 = 300). The laser particle size analyzer (LPSA) was used to analyze the d97 = 300 and the results showed a %change from 90.82% to 95.59%, with a real density of 2.830 for the waste CSD. The result of the copper upgrade showed that test 8 with treatment combination of 80 rpm and 4.5 l/min gave the highest % copper grade of 1.37 which is still less than the %grade of copper in the feed (1.49%). It thus lead to the recommendation that another type of centrifugal separator that will allow the introduction of the feed as slurry so that the pulp density and feed rate can factored into the whole upgrade experiment, consequently reducing the significant amount of losses and the chances of an improved grade and recovery of copper from this waste CSD.

Mar 1, 2018

By James T. Staley

Quenching and aging are critical processing steps used to produce precipitation hardenable aluminum alloy products. This work describes personal computer programs that employ models to predict certain properties after quenching and aging and graphically display them. One of the programs allows the user to predict the attainable strength and toughness of aluminum alloy products after an arbitrary quench. Another program simulates the changes in strength and electrical conductivity occurring during second-step aging alloy 7050-T7X products as a function of thickness, furnace temperature set point, and furnace characteristics.

Jan 1, 1993

In this study, the method of chemical co-precipitation?reduction?diffusion was developed for the preparation of magnetic SmCo5 alloy. In the chemical co-precipitation process, the effects of solution pH, the reactant concentration, the dispersant on the process were investigated. The optimum conditions of the process were determined, and the SmCo5 alloy oxide precursor particles with fine crystalline structure, narrow size distribution was obtained. Then, by reduction-diffusion treatment of the precursor particles, the SmCo5 alloy with high quality was produced. It is anticipated that the co-precipitation-reduction-diffusion is a novel method available for SmCo5 alloy production.

Jan 1, 2006

By K. B. Shedd

Questions regarding possible adverse health effects from exposure to zeolites arose when the inhabitants of two villages in Turkey were found to have high incidences of mesothelioma, a disease generally identified with exposure to asbestos. No asbestos deposits are known in the area, but some fibrous zeolites have been found. Further investigations have resulted in conflicting opinions as to whether fibrous zeolites are related to the high incidence of mesothelioma in Turkey. The U.S. Department of the Interior, Bureau of Mines examined the habits of domestic zeolites by scanning and transmission electron microscopy. Only erionite and mordenite particles possessed acicular to fibrous habits. With the exception of a rarely occurring woolly erionite sample, the fibrous zeolites were not dimensionally equivalent to asbestos.

Jan 1, 1982