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By P. Halsall

Smelters of medium or low grade tin concentrates must recover a high proportion of tin from iron-bearing slags or concentrates; the volatility of tin sulphide makes possible the production of iron-free tin fume. Laboratory work defined conditions which would promote the sulphidisation of tin slags and concentrates melted with them, to result in tin recovery as fume, and a residue of less than 0.5% Sn content, which could be controlled to vary with the value of tin. Subsequently pilot-plant work on 6-tonne and 15-tonne scale led to a commercial plant of 45 tonne. capacity (1962), for melting and fuming primary and secondary low-grade tin materials by submerged combustion. Some factors contributing to the rate of Working expressed in terms of the 'half-life and the amount of work done, the 'half-life-tonne' are studied, leading to the design and operation (1972) of the 100-tonne water-jacketed unit, presently in use, treating a wide range of slags and low tin-content ores and residues.

Jan 1, 1983

By Atinuke Oladoye, David Esezobor

"Particulate Copper Silicon carbide (Cu-SiCp) composites find application as wear and heat resistant materials in electrical sliding contacts such as in homopolar machines, railway overhead current collector systems where high electrical/thermal conductivity combined with good wear properties is required. However, challenges occur during machining due to the presence of hard reinforcement in the matrix. This may lead to high turnover of tool wear and poor surface finish. The adoption of near-net shape technology to produce such hard-to-machine metal matrix composites and subsequent finish machining with its attendant cost has reported limited success. This paper critically appraises the challenges and opportunities in the improvement of tribological characteristics of particulate Cu-SiC composites and identifies low cost reinforcement material that could be used to improve its tribological characteristics.IntroductionTribology consideration is increasingly becoming a decisive factor in the design and selection of materials for applications involving interacting surfaces in relative motion. The consideration is mainly on the combined effects of friction and lubrication on material's wear integrity and performance amongst other. Annual losses due to tribology in the US industries are estimated at between 1-2% of the Gross National Income [1], in Russia it is about 1-4% of the GDP [2]. Thus, the attributes of tribology has become imperative in modem machinery especially those applications involving sliding and rolling surfaces, and electrical contacts [3- 8].These are readily found in homopolar machines, internal combustion engines, aircraft engines, gears, cams, seals and railway overhead current collector systems [9-12]. In these systems, the dissipation of frictional heat arising from the interacting surfaces as quickly as possible imposes constraints on the choice of materials for such application to prevent softening, plastic and shear flow and the transfer of metal as wear debris onto the interacting surfaces. If these possibilities occur, system performance is compromised and premature failure may result. Materials for these systems are expected to possess high electrical and thermal conductivities, low coefficient of thermal expansion, good corrosion resistance and high melting point [3-8, 13]."

Jan 1, 2011

By C. B. Piazzarollo

Ceramic materials exhibit dispersion results after being subjected to various levels of stress, from the point of view of mechanical strength. With the focus on sustainable development and to improve the strength of these material, was incorporated ornamental rock waste into clay in up to 10% in mass to conform some samples, that was fired to 750ºC, 850ºC and 950ºC and submitted to technological tests. This paper presents an analysis of the technological properties of the samples through the use of Weibull statistic to determine which the best firing temperature for these red ceramic materials. The Weibull Modulus indicates a greater homogeneity for samples with 10R at 950ºC.

Jan 1, 2015

By T. T. Chen

Canadian Electrolytic Zinc has developed the "cement-stabilization of jarosite residue" Garofix) process to stabilize zinc plant jarosite residues for disposal. The cement-jarosite mixtures cure quickly, have good mechanical strength and low hydraulic permeability; they possess good neutralizing capability and chemical stability. In the jarofix process, Portland cement partly decomposes jarosite to form (SO4MOH)12.nH2O, ferric hydroxide and an alkali sulphate. Approximately 40% of the jarosite reacts in mixtures containing 30% cement. The jarofix product also contains various Ca-Al-Fesilicate-sulphate-hydrate phases and gypsum, which bond the individual particles together imparting mechanical strength and reducing the permeability. Most of the reactions take place in the first few hours of curing. Ammonium jarosite is slightly more reactive than sodium jarosite but releases NH3 gas; water-soluble Zn in the jarosite residue is stabilized in the cement reaction products.

Jan 1, 1996

By Zhang Yongzhu

In hydrometallurgical processes of PGMs separation and refining, differences between 1-PGMs (Ru;Rh;Pd) and h-PGMs(Os;Ir;Pt) in thermodynamics and kinetics have been observed. The successful practice in the separation and refining of PGMs in China, is mainly based on the following two kinetically extraction sequences of: (1) for the extraction of PGMs complexes in different configurations with coordination mechanism (AuCI,) -> (MCl6)2-> (MCl4 )2-> (MCI6) 3- , and the substitution rate for h-PGMs complexes with higher effective nuclear charge Z' is much more slow than that of I-PGMs. and (2) for the extraction of PGMs in different configurations with oxonium (or ion -exchange) mechanism (AuCl4)-> (MCl4)2--> (MCl6)2-> (MCl6)3- and the extraction of h-PGMs complexes with low surface charge density is more fast than that of I-PGMs complexes. In view of atomic structure theory, the similarity of atomic radii and chemical properties and difficult separation of PGMs resulted from the Lanthanide Contruction between 5th period (1-PGMs) and 6th period (h-PGMs). The differences between h-PGMs and 1-PGMs are due to the loss shielding of 4f subshells on 5d electrons for h-PGMs with higher nuclear number, which makes h-PGMs have a higher Z' (effective nuclear charge) and strong attraction for outer space electrons. As a result, h-PGMs metals and complexes are thermodynamically more stable and kinetically more inert than the corresponding 1-PGMs. The differences between h-PGMs and 1 -PGMs in aspects of elements properties, complexes, hydration, substitution and redox reactions , are discussed.

Jan 1, 1993

By Lloyd R. Nelson

Selective carbothermic reduction is the preferred method of treatment of electric arc furnace (EAF) dust (listed hazardous waste, K061). The process maximizes the recovery of recyclable constituents by concurrent production of saleable zinc metal (directly condensed from the furnace off-gases), an innocuous, disposable iron oxide-rich slag, and some metallic iron. Results of a mineralogical investigation of a foaming slag produced during selective carbothermic reduction treatment of EAF dusts are presented. Wiistite and tricalcium silicate were identified by reflected light microscopy as the primary crystalline phases contained in a glassy matrix, but this technique failed to reveal any solid phases that could have significantly contributed to foam stability. It was concluded therefore, that the foam had been unstable, and had been primarily generated by copious gas evolution associated with the sudden reduction of the slag by an inadvertent addition of carbonaceous reductant. This is consistent with the susceptibility to foaming, when subjected to sudden excesses of carbon, of the slags produced by selective carbothermic reduction, because they still contain unreduced components such as iron oxide.

Jan 1, 1994

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 C. P. Snyman

Three independent methods of coal classification can be distinguished, namely on the basis of grade, type and rank. The latter two can be determined accurately and unambiguously only by means of microscopical techniques. These three independent variables affect all the coal properties and therefore also the technological behaviour of a particular coal. The influence of the inorganic constituents of coal on the fusibility of the ash and on the length of the slag, and also on fouling and slagging, is discussed. The fractionation of the ash-forming constituents during combustion and gasification of pulverised coal shows that fouling and slagging are not related directly to the fusibility and composition of ash of the coal as a whole. The results of combustion experiments using a drop furnace technique indicate that the ignition temperatures of the light volatiles in the coal, and of the formed char, as well as the burn-out time of the char are more dependent on the rank than on the type or grade of the original coal. High-ash coals, however, apparently ignite at lower temperatures and are more reactive than low-ash coals of similar type and rank. The surface properties of coal, which are important in froth flotation and oil agglomeration, correlate well with the inherent moisture content (and by inference with the heat of wetting and the calorific value) and therefore with the type and rank of the coal. In coal exploration, variations of rank offer the possibility of predicting the presence of an intrusion near the seam, thus contributing to more effective exploration and mine planning.

Jan 1, 1991

By Larry G. Twidwell, Jannette L. Chorney, Bryce D. Ruffier, Katelyn M. Lyons, Daniel W. Gaede, Ryan J. Foy, Jerome P. Downey

The Metallurgical and Materials Engineering Department at Montana Tech is investigating various methods of extracting and refining rare earth elements from mineral ores and concentrates. As part of this research, an elevated temperature “roasting” process has been evaluated as a means of converting the rare earth elements contained in various matrices to bromides as a pretreatment step in preparation for downstream rare earth element extraction and recovery operations. Laboratory and bench-scale experiments have been performed to assess the effects of varying temperature (150 to 400° C), time (1 to 4 h), and the ammonium bromide to rare earth oxide molar ratio (6 to 24) in the roaster charge. The results show that nearly complete bromination of the rare earth oxide is achievable when the roast is performed under optimum conditions.

Jan 1, 2015

By H. H. Kellogg

The thermochemical properties of molten solutions in the binaries Cu-Bi, Cu-Sb and Bi-Sb, as well as the ternary Cu-Bi-Sb, have been correlated and described in mathematical form by use of the associated species concept combined with the three-suffix Margules equations to account for the non-idea 1 behavior of the solution species. Agreement of the correlations with experimental data is excellent (relative deviation of less than 2.5% in the values of the activity coefficients) in most cases. The correlations are applicable over the entire composition range of each system, and in the temperature range 700°-1250°C.

Jan 1, 1985

By H. H. Kellogg

The Process Fuel Equivalent (PFE) for nine different flowsheets for production of anode copper from sulfide concentrates has been evaluated and compared for a set of uniform conditions and a "standard" concentrate analysis. The processes considered are: reverberatory smelting, (wet-charge and hot-calcine charge), electric furnace smelting, Outokumpu flash smelting (2 versions), mom flash smelting, Noranda Continuous Process (2 versions), and the Mitsubishi Continuous Process. The energy required for the numerous processes auxiliary to the principal smelting processes-¬roasting, drying, air compression, gas handling, dust collection, slag cleaning, acid manufacture, etc.--are separately evaluated and incor¬porated into the process comparisons. The factors in process design that lead to important energy savings are: use of fuel rather than electric energy; use of oil or coal rather than natural gas; maximum use of oxygen enrichment of the process air; drying of charge before smelting, or, even better, drying and preheating of charge by partial roasting in a fluid-bed; recovery of waste heat from all major hot process gases.

Jan 1, 1976

By Katri Avarmaa

Aluminum and copper are large volume metals in electronic appliances, while tin and indium exist as common minor elements. All of these non-ferrous metals are aimed to be separated and recycled from the end-of-life electronics into non-ferrous scrap fraction(s), and further through pyrometallurgical and/or hydrometallurgical processes to pure metals. Depending on the mechanical pre-treatment processes, aluminum and copper liberation from each other varies. This study focuses on the influence of alumina on indium and tin distributions between copper alloy and iron silicate slags with 0, 9 and ∼16 wt% of Al2O3. The experiments were executed with an equilibration-quenching-EPMA technique in an oxygen pressure range of 10−10–10−5 atm at 1300 °C. The metal-slag distribution coefficient of indium remains constant as a function of alumina in slag, while that of tin increases. Therefore, aluminum in feed or alumina addition to the slag improves the recovery of tin into copper. Nevertheless, oxygen pressure has clearly more significant influence on the behavior of both the metals in the smelting conditions.

By A. Kontopoulos

The Olympias Mine in Northern Greece is producing an extremely refractory gold-bearing arsenical pyrite concentrate, containing on the average 41 3 S, 40 3 Fe, 10-12 3 As, 25 ppm Au and 35 ppm Ag. During the process selection stage, more than a dozen alternative technologies? were considered and an in-depth analysis was prepared for the three most promising, ie roasting, pressure oxidation and biological oxidation. Detailed capital and operating cost estimates were prepared, based, where appropriate, on laboratory and pilot-plant tests. A number of criteria was used for process evaluation and selection, including capital and operating costs; environmental impact, gold' recovery, stage of development, etc. Based on the above evaluation, the Sherritt Pressure Oxidation Process was finally selected. A detailed description of the process selection stage, supported with laboratory and pilot-plant test results on many of the processes considered, will be? presented.

Jan 1, 1989

By Frederic Pineau

Semisolid metal alloys have a special microstructure of globular grains suspended in a liquid metal matrix. This particular physical state of the matter can be exploited to produce near-net- shape parts with improved mechanical properties. However, the behavior of the slurry is strongly influenced by the local solid fraction and state of agglomeration. Different flow instabilities ·associated with the combined flow and solidification process result, which make difficult the application of semi-solid processing in the casting industry. Moreover, the rheology of semisolid materials is not well understood. Most of the theory has been derived from experimental data, which are somewhat difficult to measure. A model that accounts for the multiphase nature of semisolid slurries is required to get more insight into such complex flows. This paper describes a mixture model for semisolid slurries. It assumes that the mixture of liquid-solid components behaves as a single fluid as far as overall mass and momentum balances are concerned. The coupling force between the phases is derived on the assumption that the slurry is a fluid saturated isotropic media. The proposed methodology is implemented in a finite element code. The model is then applied to the the filling of an industrial-scale capillary flow viscometer. Segregation patterns are obtained and discussed.

Jan 1, 2001

By Minting Li, Hailong Yang, ChangWei, Cunxiong Li, Gang Fan, Xingbin Li, ZhiganDeng

The filtration problems on acid leaching sludge of high silicon zinc ore have been paid extensive attention in zinc hydrometallurgy. It was found that soluble silica can be effectively converted into silica precipitate with good settling, filtration and washing properties, and the filtration rate can be in excess of 800 L/m2 · h under certain leaching conditions. According to investigating on the filtration rate, viscosity and concentration of silica of leaching sludge or liquor, the filtering temperature can tremendously improve the filtration property of pulp. At the same time, the experimental data indicated that the viscosity of leaching liquor was the key factor influencing filtration property of leaching sludge.

Jan 1, 2016

By Larry M. Southwick

Steel mill electric arc furnace dust is a RCRA listed hazardous waste and its treatment and/or disposal are regulated by a complex set of rules. These regulations were originally established to encourage recovery and recycling of valuable components. For EAF dust, the more valuable constituents include zinc, lead, cadmium and iron. In fact, current trends are in the opposite direction, as the regulations have complicated the ability to commercialize new treatment technologies and created substantial roadblocks and liabilities for processors. As a result, almost half of the EAF dust generated in 1997 will be landfilled. The problems are compounded by difficult processing requirements, less than sterling examples of technology development and mechanical and operating problems. This paper explores some options to simplify the processing requirements and thereby easing difficulties in commercializing new technologies and expediting the recycling of recovered metals. Dust processing usually includes a simple step followed by two complicated steps. The simple step is fuming of heavy metals away from iron and other residues. The complex steps are (1) separating and purifying the heavy metals and (2) upgrading the iron residue. The first complex step can be simplified by producing an intermediate product that is amenable to processing by zinc refiners. This route benefits from the currently underutilized (by dust processors) resource offered by refiners, who have experience in and existing processes for separation and purification of zinc-based heavy metals. Various processes and their associated product options are reviewed and compared. Future directions for dust processing developments are suggested.

Jan 1, 1998

By Farhang Hedjazi

Anglo Asian Mining have recently installed an industrial-scale UF/RO plant to treat process liquors from the integrated heap leach/agitation leach/ resin-in-pulp gold ore treatment facilities at their Gedabek gold-copper mine in Azerbaijan. The UF/RO plant is designed to treat 60 m3/h of leach solution to produce discharge quality water. The RO concentrate, which contains elevated concentrations of copper, silver and cyanide, is sent to the company’s SART plant for the recovery of the metal values as a precipitated sulphide concentrate and the cyanide, which is recycled to leaching. The new water treatment plant improves the sustainability of the operations at Gedabek by enabling replacement of fresh water input with RO permeate and safe discharge of permeate to the environment, during periods of excess water balance. The paper includes pilot plant data and early results from the full-scale plant.

By Sen-xiang Yang, Xin-teng Liang, Gui-jun Li, Jian-hua Zeng, Yong Chen

"This research is based on PANSTEEL 120t steelmaking converter technology to have the quantitative description of the time needed in uniform mixing of molten steel in the converter with the computer. In present work, the numerical simulation approach is used to analyze oxygen lance nozzle, the flow condition of oxygen and flow status of molten steel in the converter. The various oxygen jet flows that come out from different angles and the flow status of all kinds of jet flows in the converter have also been simulated. All of the simulation parameters are based on the specifically practical conditions according to the physical conditions of PANSTEEL 120 t steelmaking converter. Through numerical simulation, the angle parameter of the oxygen lance nozzle is 16 °. The optimized oxygen lance 536-16 has a good performance in industrial application. This kind of phenomenon shows that the ways and processes of numerical simulation in this research are right.IntroductionThe oxygen lance system is the significant process in semi-steel making converter. It's related to whether the converter or even the whole system can function well. While in actual production, many problems emerge in the process of using the former oxygen lance, such as re-drying, slopping, high lance position, dead burning and even blowing out. In continuous fast-paced process, the unstableness of oxygen lance will lead to speed droop or even stop pouring. Analysis shows that all these problems are not only related to the raw materials but also the design of oxygen lance. Bad oxygen lance's scorification kinetics condition and low content of FeOn in early slag are the direct factors that we cannot easily control in steelmaking at present [l]. Therefore, the good scorification kinetics condition which is related to nozzle has good influence on BOF steel making."

Jan 1, 2013

By Darrin Wikoff

"The data, compiled by the Department of Energy (DOE), indicates that the average industrial plant could reduce its total energy cost by 14.8% by implementing effective Life Cycle Asset Management processes. The actual savings varies by industrial classification, but in all cases the potential is substantial and could have a marked impact on the operating profit of the company.Improvements geared towards improving equipment reliability have distinctive linkages to environmental performance, such as reducing the amount of product and raw material waste through routine monitoring of system parameters through predictive technologies, and preventing interruptions to production cycles with a focus on Overall Equipment Effectiveness (OEE).Alcoa successfully reduced solvent disposal costs by more than 40% and GE reduced greenhouse gas emissions by more than 250,000 metric tons. This presentation will show you how companies have successfully reduced energy and disposal costs through a focused effort on manufacturing process reliability.IntroductionSmelter in the ParkThe quaint town of Portland, Victoria protrudes outward towards Antarctica from Australia’s southeastern coastline. Portland is a quiet rural community surrounded by agriculture that draws tourists by the thousands to the southernmost edge of Victoria by way of breathtaking cliff top views of the majestic Southern Ocean, the intrigue of shipwreck coves along the Great Ocean Road, and what most will call the eighth wonder of the modern world, the “Smelter in the Park”. Integrated within Portland’s beautiful landscape is a 356,000 ton/year aluminum smelter that stands as a symbol of collaboration between nature and industry. Nestled atop a ridge which faces “Sail Rock”, a popular destination of local and visiting fisherman, the smelter is engulfed in a mix of brush and wetland preserves that are home to many of Australia’s feathered and fourlegged natives. Also within its interior you’ll find parks and natural landscapes abundant where man and machines coexist with the native inhabitants."

Jan 1, 2009

By Harovel G. Wheat

It has been shown that the incorporation of fly ash into concrete as a replacement for part of the cement can be beneficial. In some cases, the strength of the concrete can be increased and the permeability can be decreased. This latter property can lead to a reduction in the migration and/or penetration of aggressive species into reinforced concrete. Some of these species, such as chlorides from deicing salts or marine environments, can subsequently result in accelerated corrosion of the steel reinforcement, a loss of the protection provided by the passive film on steel, and a loss of structural integrity of the concrete. Care has to be taken so that the appropriate compositions of the components of the fly ash are utilized in order to ensure maximum benefit to the concrete structures. This will be discussed as it relates to fly ash generation and treatment.

Jan 1, 2002