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By Ray Y. Lin, Sunil G. Warrier

"Low cost processing of metal matrix composites is an essential requirement for this class of materials to be acceptable in commercial application. In an effort to reduce the cost of processing of metal matrix composites, an infrared pressureless liquid infiltration technique has been developed. The salient features of infrared infiltration are that it is rapid, simple and a low cost process. The rapid processing capability causes very little oxide formation on the alloy resulting in both improved wetting and flow characteristics and reduced oxygen contamination in the composite. Thus, vacuum is normally not required. Using infrared inflltration, aluminum and titanium matrix composites have been prepared under an ambient argon atmosphere. Reinforcements in these composites include carbon fibers, silicon carbide Nicalon fibers and Textron's SCS fibers. Microstructural and mechanical test results indicate that completely consolidated composites with good fiber distribution, limited interfacial reaction and high mechanical properties can be manufactured by this process. IntroductionAluminum and titanium matrix composites reinforced with ceramic reinforcements are strong candidates for numerous applications in the aerospace and automotive industries. Aluminum matrix composites are commonly fabricated by either solid state vacuum hot pressing, liquid state pressure infiltration or squeeze casting [1]. Although liquid state pressure infiltration and squeeze casting has significant advantages over solid state processes, the requirement for pressure makes these composites uneconomical for large scale industrial application. Titanium matrix composites are primarily fabricated by solid state diffusion bonding [2]. Pressureless liquid infiltration can significantly reduce the cost of fabrication in both the composite systems. However, during pressureless infiltration processes, several complications concerning the wetting characteristics and chemical compatibility arise."

Jan 1, 1994

By F. L. Marley

Small and medium-sized flotation plants with no assaying instrumentation still depend much upon the art of the operator to produce acceptable and consistent results. Improved performance can be accomplished by the use of the simple microscope set up as a control device. The visual recognition of products in the circuit does much to eliminate uncertain shift operating decisions and is an easy technique to acquire. Mineral staining methods further assist in the determination of components within the mill products. Simple mounting upon scotch tape and other adhesives is rapid and convenient. The microscope also has a practical role for the plant metallurgist or laboratory technician when evaluating middling products, and their routing within the circuit. Examples are reviewed where the microscope has been used for operational control in both sulfide and nonmetallic mineral flotation plants.

Jan 1, 1981

By Thomas Havlik

It is proposed to realise the direct leaching, during which will be generated elemental sulfur and not sulfate or sulfuric acid as end product, under conditions that sulfur will not cover the leaching surface and Hot hinder the leaching course. The following improvements have been considered: -use of organic sulfur solvents -ultra high-frequency leaching -ultrasonic leaching -use of surface detergents or surfactants in leaching processes -simultaneously crushing and leaching These proposals are under investigation and preliminary results are promising

Jan 1, 1996

By H. -Peter Sattler

The laser sorting technique for replacing the handpicking of the non-ferrous metal scrap from auto shredders was first introduced 1990, The process is based on the use of atomic emission spectroscopy induced by lasers to identify the scrap particles and sort them with adequate systems into main fractions of Al-, Zn-and Cu-alloys, stainless steel and lead, In the meantime the handling technique for the scrap, i.e. the singling and sorting technique as well as the analytical detector were further developed for more efficiency and higher reliability, i,e. less maintenance, minor sorting errors etc. These developments were mainly based, on and initiated by operational experiences from the startup phase of a first production plant. Part of the on going research work was the development of an ,aluminium detector which makes it the first time possible to sort mixed aluminium scrap automatically into specific alloy fractions.

Jan 1, 1995

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 Wenbo Luo, Jilai Xue, Tiepeng Li, Jun Zhu

Sodium silicate solutions for producing silica have been ultrasound treated to enhance the precipitation process in laboratory scale. Higher precipitation rate was found with ultrasound treated solutions than those without ultrasound. The obtained SiO2 powder products were characterized using XRD, SEM, BET and laser particle size analyzer. The particle size distribution and the specific surface area of the powder products varied with the power input level and the processing time of the ultrasonic treatment. The results indicate that the efficiency of the precipitation process can be improved optimally when the ultrasound is conducted into the solutions before the nucleation stage.

Jan 1, 2015

By Hua-qing Li

Electromagnetic stirring process effectively improves the casting quality of metals. In this paper, the physical simulation experiment, in which the molten copper is displaced by mercury, was designed. The factory test parameters were determined according the simulated data. The flow behavior of the mercury to be stirred as well as the relations between the microstructure of plate blanks and the current parameters were analyzed. With an appropriate electromagnetic stirring, the inverse segregation of tin for C51900 alloy plant blank reduces from 15 % ~ 30 % to about 5 %, and the proportion of equiaxed grain rises to larger than 30%.

Jan 1, 2009

By T. P. R. de Jong

Dual energy X-ray transmission imaging is extensively applied for safety luggage inspection. Its advantages are its rapid scanning rate (25 to 100 cm/sec) at approximately I mm resolution and simultaneous thickness independent metal identification. This is especially advantageous for secondary scrap metal inspection and automatic sorting. Other applications include metal product inspection, bale control, and waste processing. Recent progress in development of an automatic on-line sorter for bulk solids is presented and discussed. Besides various non-metal applications (solid fuels, wastes etc.) it appeared particularly effective in light metal sorting. As inspection tool better control of difficult to monitor solid bulk streams, batteries, bales and other related metals becomes possible.

Jan 1, 2003

By M. J. Collins

Pressure leaching of zinc sulphide concentrates has been practiced commercially for nearly two decades. The process, which includes direct leaching of concentrate with spent electrolyte in an autoclave, has been commercialized at four separate locations to date. In pilot studies carried out in the Dynatec lab in Fort Saskatchewan, dozens of additional zinc concentrates have been shown to be amenable to pressure leaching. This paper highlights recent improvements in zinc pressure leaching that have been identified through process development studies, and how the experience gained in these studies has been utilized in the development of a new copper pressure leach process.

Jan 1, 2000

By C. Burton Clark

The important role of the petrographic microscope in the petrology of refractories is discussed, based on 45 years of industrial experience by the author. Highlights of his career are used to illustrate improvements in equipment and techniques during the period. Two specific investigations are described which emphasize the interrelated use of the petrographic microscope with other instruments such as the x-ray diffractometer and scanning electron microscope. Emphasis is placed on the use of phase equilibrium diagrams for guidance in predicting and interpreting reactions that occur under non-equilibrium conditions in the manufacture and use of refractories.

Jan 1, 1982

By Guiming Yang, Xiaoxian Huang, Zhiyun Ji, Min Gan, Lishun Yuan, Xiaohui Fan, Zhiyuan Yu

"The roasting characteristics of hematite pellets containing MgO were studied where magnesia powder, serpentine and magnesite were used as magnesium-additives respectively. The mechanical strength of both preheated and roasted pellets decreased when MgO content increased, which implied the addition of MgO had an adverse effect on pellet consolidation. By adding flux containing CaO, the mechanical strength of both preheated and roasted pellets were improved. The addition of calcium flux facilitated the formation of calcium ferrite and provided a certain amount of liquid phase, resulting in faster diffusion ofMg2+ and Fe3+. The result showed that diffusing speed of Mg2+ was enhanced by 1.48 times, and rate constant of Fe203 crystalline growth was enhanced by 62% when basicity was around 0.4. Improvement of mineralization degree and recrystallization of Fe203 assisted in consolidation of hematite pellets containing MgO.IntroductionOxidized pellets are ideal iron-bearing burdens in blast furnace. At present, magnetite is the main raw material for oxidized pellet production in China. However, as the rapid development of iron and steel industry, resources of magnetite have been depleted and cannot satisfy the requirement of pellet production. Using hematite concentrates to produce oxidized pellets has become a trend [1, 2]. Many pellet enterprises abroad nowadays have adopted high proportions of hematite concentrates when producing oxidized pellets, e.g. the percentage is 100% in a lot of Brazilian factories [3, 4]. But high proportion of hematite concentrates will lead to low mechanical strength and high reduction swelling index of pellets. Some studies show that Mg-bearing pellets have excellent metallurgical properties, and the reduction swelling phenomenon can be solved by adding fluxes containing MgO [5, 7]. However, there are problems such as low pellet strength and bad roasting characteristics for MgO-bearing pellets, which remains an obstacle in pellet industry. Hence, it's vital to undertake the study on strengthening measures for indurations of Mg-bearing hematite pellets."

Jan 1, 2013

By J. D. Miller

Air-sparged hydrocyclone (ASH) flotation is a high-capacity flotation technology originally developed in the Department of Metallurgical Engineering at the University of Utah for processing mineral resources. However, the technology has been found to be useful in industrial waste processing, in the recycle of secondary resources, and in remediation of environmental problems. For example, areas in which the ASH technology is expected to have potential application include cleaning of waste coal fines, air stripping to remove volatile organics from drinking and process water, water disinfection by ozone or chlorine sparging, dispersed oil removal from water, and contaminated soil remediation. Recently, the ASH has been studied extensively for deinking flotation in the wastepaper recycling industry and has been shown to have excellent efficiency/capacity. In fact, a 20-million-dollar plant has been in operation since June 1992. The ASH technology can provide a specific capacity hundreds of times more than that which can be achieved with conventional flotation equipment and in certain instances is expected to provide superior separation efficiencies when compared to other technologies. The design and principles of ASH flotation are described. Experimental data for fine coal flotation, volatile organics stripping, and deinking flotation for paper recycle are presented and discussed. Finally, other potential areas of application for environmental technology are considered.

Jan 1, 1993

By Marco V. Ginatta

Current world production, 60'000 ton/y, is exceedingly too small for titanium's extraordinary combination of favorable properties; it should be 1,000,000 ton/y (7% of stainless-steel). Prices that competitively sustain that sales volume are achievable only with electrolytic production, as it is for all other commercial nonferrous metals. But titanium does not have its commercial electrolytic plants yet, because of producers decisions and strategies, scientists works, industrial problems with chloride process, lack of consumers sponsors. Fluoride high temperature process has the advantages of aluminum electrolysis, plus other favorable characteristics specific to titanium and its feed material. One electrolytic titanium potroom replaces several different plants used for sponge production. Production of titanium ingots with zero defect is achieved. The solidified cathode rectangular slabs are suitable for direct rolling.

Jan 1, 2001

By Signe Kjelstrup, Leiv Kolbeinsen, Marit Takla, Odne Burheim

"This paper presents a Seebeck-type solid state thermoelectric power generator unit, designed to investigate the possible recovery of radiant waste heat at a silicon plant in Norway where roughly 703 of the total input energy leaves the process as waste heat. The unit is 0.5 m x 0.5 m and is built of 36 commercially available thermoelectric devices based on bismuth telluride p - and n - type semiconductors. Thermoelectric devices directly convert fractions of a heat flux into an electric current (and vice versa) and may therefore be convenient for recovery of waste heat when the heat source is discontinuously available. The purpose of the thermoelectric unit is to give a proof of principle of direct thermoelectric energy conversion on a large scale. We present the initial test results for the generator. At an average temperature difference between the heat reservoir and the heat sink of 98°C, we measured an open ciruit potential of 23.44 ± 0.06 V and the matched load power output was 39.4 W. At a temperature difference of 220°C, we predict the generator open circuit potential to be 40.8 V, which corresponds to an efficient Seebeck coefficient of 242 µV /K, and matched load power output to be 120 W.IntroductionThe world's power demand increases, driven by population growth and increase in living standards and simultaneously global warming is recognized as one of our most serious environmental problems. According to the International Energy Agency[l], the industrial sector accounted for approximately one third of the total global power consumption in 2005. Increasing the energy efficiency of industrial processes thus represents a benign and substantial route for addressing environmental concerns and energy security.In accordance with the second law of thermodynamics, all real processes are associated with lost work which is energy being dissipated as heat to the surroundings[2]. Improving the energy efficiency of industrial processes is about finding the process path associated with a minimum of lost work. The more evenly the losses are distributed, the smaller are the losses [3, 4]. In addition, exploiting the unavoidable waste heat will contribute to improve the energy efficiency. The waste heat may be utilized for heating purposes and/or it can be upgraded to work for instance via some sort of heat engine."

Jan 1, 2012

By Arsenio Enriquez, Adrian Deneys

"Rio Tinto through its subsidiary Kennecott Utah Copper Corporation (KUC) and Praxair have implemented the CoJet® gas injection system for copper anode refining. The system provides the capability to melt on average 60 to 70 tons of scrap copper per heat (with acceptable NOx emissions). The system has demonstrated the potential for tuyere-less sulfur and oxygen removal using coherent jet technology.This paper describes the process concept, system development, laboratory testing, implementation, current operation and ongoing developments."

Jan 1, 2009

By Camila Martini Matos, Maria das Graças da Silva Valenzuela, Francisco Rolando Valenzuela Diaz, Lucy Gomes de Sant' Anna, Orley de Oliveira Magalhães, Flavio M. S. Carvalho, Isaac Jamil Sayeg

"Kaolin clays are widely used in various industry segments. Its main properties are fine granulometry, chemical inertness and whiteness. In general, kaolins are not easily organophiilized as a result of its 1: 1 structure. The aim of this paper is to describe the modification of a Brazilian kaolin sample, in order to obtain an organophilic kaolin of high performance. The clay as received was identified by X-ray diffraction and characterized by optical microscopy, cation exchange capacity and swelling tests for observation of their performance in water and organic solvents. Then, the sample was treated with a 10% sodium carbonate solution and with ammonium quaternary, washed several times with distilled water, dried at 60°C, and characterized by XRD and swelling assays. Our results show that the clay was organophiilized and its ability to swell in organic solvents has increased.IntroductionThe kaolin clay, also known as ""china clay"" is chemically a hydrated aluminum silicate characterized as a very fine powder and lamellar structure (1:1), being constituted mainly by kaolinite [l]. Kaolin is a mineral extremely used as raw material. Its properties such as color, softness, small particle size and chemical inertness make it a suitable material for several industrial applications. The desired properties of kaolin varies widely for each application, beginning with its largest use in the paper industry until minor uses in the sectors of cosmetics and pharmaceutics. These two last applications require purified kaolin with defined functionality [2]. To find improvements in the functionality of kaolin for specific applications is important for many industrial uses. Sometimes the way to find these improvements might be modification of the kaolin clay by treatment with a chemical substance as ammonium quaternary, causing surface modifications [3,4]. In this work is described the modification of a Brazilian kaolin sample by treatment with cetyl trimethylammonium chloride (CTAC). The properties of the modified kaolin are being assessed by characterization and essays to understand its functionality and industrial application."

Jan 1, 2013

By Jared Ball, Darren Snashall, Paul Telford, Pengfu Tan, Ben Hogg

"The foamed converter charges were up to 3 8 per month in Xstrata Copper Smelter at Mount Isa. The issue of high converter foamover frequency had remained unsolved for many decades in Mount Isa. A thermodynamic model of copper P-S converter and a viscosity model of converter slag have been developed to simulate the slag blow and copper blow, in order to understand the mechanism of converter foamover. The model predicts the chemistry and viscosity of slag during slag blow and copper blow. The effects of oxygen potential, charge of dirty reverts, slag carryover, under-blowing, over-blowing, and temperature on the foamover and viscosity of slag in copper blow have been discussed. A theory has been developed to understand the mechanism of converter foamover. The practical solutions have also been developed and implemented in Mount Isa Copper Smelter. Some improvements of the industrial operations have been presented. After a series of improvements, the number of foamed charges per month in the converter operations has been decreased significantly from 35 in Aug 2008 to only one per month in 2009/2010.1. IntroductionThe Copper Smelter in Mount Isa receives the concentrate containing about 25% copper and produces anode copper that contains about 99% copper. There are several stages in the process. The first stage carries out in the ISASMELT™ furnace. The ISASMELT™ process produces a molten copper matte containing about 60% copper. An iron-silica slag and a sulfur dioxidebearing off-gas are the by-products of the process. The slag is taken to the slag dams for cooling before it is recycled through the Mount Isa Copper Concentrator.The matte is sent to Peirce-Smith converters. The converters further remove iron and sulphur to produce blister copper which contains about 97% copper. The anode furnaces remove any remaining sulphur and oxygen to produce anode copper that is about 99. 7% pure. This is cast into anodes and sent to the Xstrata Copper Refinery in Townsville for final refining.In the copper pyrometallurgical industrials, slag foaming is an important phenomena which occurs when the gas bubbles have stability and not rupture. Foaming greatly increases the interfacial area between matte, slag and gas and is essential for the operation of high intensity smelting processes. However, foaming or foamover is undesirable in P-S converter since it can damage the equipment and injure the operators. Figure 1 shows that the whole process of a foamover development in a converter."

Jan 1, 2011

By R. Luo, R. V. Kumar

"The co-deposition of cobalt and nickel as a binary alloy has been studied by both cyclic voltammetry and long-period controlled-potential electrolysis. Cyclic voltammetry experiments showed that the cathodic current density for the mixed Co-Ni (Co-Ni=1:3) electrolyte is noticeably higher than that obtained on electrolyte containing single CO2+ or Ni2+ (II) salt of the same ionic strength. The onset potential observed for the mixed salts electrolyte was also less cathodic (negative) than that for the single metal salts, respectively. The effects of a number of operational and compositional parameters on the co-deposition of cobalt and nickel were studied. The parameters under investigation include cathode (deposition) potential, temperature, CI-/Sol ratio in the electrolyte, the amount of additives such as H3B03, and acidity of the electrolyte.Optimum operational conditions were established for the deposition of cobalt and nickel binary alloy. These results are discussed with respect to feasibility of reclaiming cobalt, nickel and chromium from mixed superalloy scraps by melt-refining (under nitrogen and/or ammonia), followed by electrorerining of cast anode for co-depositing Co/Ni and thermal decomposition of chromium nitride for recovering chromium metal."

Jan 1, 1997

By R. Gordon Bloomquist

The economic benefits of the co-production of minerals from geothermal brines far exceeds the potential revenue stream from the sale of marketable by-products such as silica, zinc, manganese, lithium and a number of rare earths. Extraction of silica can avoid scaling problems often associated with many geothermal power projects and may allow for additional power production through the use of bottoming cycles or the use of the brine in direct use applications now impractical due to scaling problems. An additional benefit of silica removal is the opportunity to use the geothermal brine as a source of water for enhanced evaporative cooling ? a technique that can significantly improve the summer power output from binary power plants employing air cooling for condensing the working fluid.

Jan 1, 2006

By S. Kurama

Incorporation of de-watering sieve waste of borax (TSW) from Etibor Kirka Borax Company (Turkey) on the mechanical and physical properties of a commercial floor tile composition was investigated. In order to achieve this aim, TSW was partially employed in place of feldspar in the standard composition up to 20 wt %. The formulated compositions were wet milled, dried, shaped and then fired at 1190C for a total firing time of 38 minutes (from cold to cold) under industrial conditions. It was found that using of TSW up to 15 wt % improved the physical and mechanical properties of final product. The results indicated a good prospect for TSW as a co-flux in floor tile formulations.

Jan 1, 2006