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By D. McConchie

Management of caustic red mud wastes at the QAL bauxite refinery uses an innovative approach . involving neutralising the red mud with seawater; solids settle in a Red Mud Dam and residual water (pH = 8.6) is discharged to a tidal inlet. A survey of 18 trace elements in sediment, water, mangroves and molluscs, and an ecological survey of benthic fauna in the inlet, and at near-pristine control sites, revealed no significant trends that were linked to the discharge, except for the concentration of Al which was slightly elevated within 100m of the outfall. Trace element concentrations in water samples were close to, or below, world average seawater values and oysters collected near the outfall were acceptable for human consumption. The impact of discharges is minimised by a high tidal range, >60% flushing of the inlet in each tidal cycle, and the very high trace element binding capacity of sediment in the dam (> 100meq/ 100g dry mud).

Jan 1, 1996

By D. J. Cassidy

This document discusses commercial strategies and applications of specialty processing plants for the recycling of nickel, copper, zinc and cobalt bearing by-products. For this discussion, I will focus on materials originating from the metal plating, electronic circuit board· and chemical industries. The review of select processes and the required service, sourcing, material handling, processing and marketing strategies necessary for a successful recycling program are highlighted. Materials discussed in this summary include filtercakes, filters, dusts, spent catalysts, spent solutions and solids. Both pyrometallurgical and hyrometallurgical applications to these materials are addressed. A comparison of targeted finished markets, including smelter feeds and value added products are also reviewed.

Jan 1, 2000

By Keith Rozenburg, Ivar Reimanis, Jesus Chapa

"Experiments in conjunction with finite element analysis (FEA) are used to better predict crack propagation in ductile/brittle graded composites. Cu/W graded composites were fabricated by stacking discrete layers of powders and hot pressing. Crack propagation was studied by loading a notched beam in four point bending and examining the subsequent crack deflection. The notch was placed within a particular composition of material, oriented in a direction perpendicular to the gradient direction. Elastic and plastic mismatch between different constituents in the graded composite induce shifts in the phase angle of loading, thereby causing the crack to deflect. FEA indicates that thermal residual stress has a negligible ""influence on the crack path. The combined FEA and experimental results suggest that elastic mismatch is the single most important material property-related factor in controlling crack deflection.IntroductionMany 'applications would benefit or may even require materials whose performance or functionality must vary spatially. While the concept of functionally graded materials has existed for nearly one hundred years, it is only within the last fifteen years, that research efforts have focused on generic issues in processing, properties and performance of functionally graded materials. This generic research effort has brought together scientists and engineers from traditionally different disciplines to address common issues with graded composites. The current work focuses on issues in structural joining. A wide variety of applications require some type of joining between dissimilar materials. Examples include thermal barrier coatings for turbine engines, wear resistant coatings for tools, ceramic engine parts, and microeiectronic devices, as well as many traditional applications involving metallic welding. The joints may either be discrete, involving a single interface, or they may· be spatially graded in composition. Extensive theoretical and experimental information exists on discrete bimaterial and trimaterial joints, but relatively little exists for graded joints or composites"

Jan 1, 2000

By A. Hasko

Phytoremediation is a new low cost alternative technique for remediation of contaminated soils from heavy metals that are emitted by ferrous and nonferrous mining and extracting processes. It is based on the possibility to use several plants that accumulate high level of metals in order to remove metallic pollutants from soils and render them harmless. Phytoextraction is an adjacent new technique that uses these hyper-accumulator plants in order to extract the metals from them using even the conventional smelting or refming processes. In our previous work, an extensive investigation of about 150 plants have been carried and several species were identified that could be used for nickel phytoremediation and phytoextraction because of their high accumulation of nickel. It has been found that five taxa from Alyssum genus specie had the highest ability to accumulate nickel with concentrations more than 10000 ug/g (dry weight) or 1%. The taxa showing the highest accumulation of this metal is Alyssum murale var. chlorocarpum with 28 600 ug/g or 2.86%, a good candidate for Phytoextraction. In this work, in order to optimize the phytoremediation and phytoextraction processes further Absorption Spectrometry measurements and biological studies were carried out to determine the parts of the plants that accumulate the highest amount of nickel and the best biological cycle during which they accumulate the highest amount. The results show that the greatest accumulation of nickel occurred in the leaf material (2.86%) and the least in the roots (0.43%). The investigation of the biological cycle of the genus Alyssum showed that: (1) the seeds germinated between 50 C to 30 0 C and more in 25 0 C; (2) 62.9 % of seeds germinated at A.m. var. chlorocarpum; (3) the emergence is almost continue from March to April; (4) the anthesis occurs from May to July; (5) the ripening of the fruit takes place 30 days after flowering; (6) the dissemination of fruits occurs from September to October. Due to these special characteristics it is reaffirmed that Alyssum murale var. chlorocarpum, as a nickel hyperaccumulator, is the most promising plant to be used for feasible phytoremedation and phytoextraction purposes. Keywords: Key words: Phytoextraction, PhytoRemediation, Nickel accumulators, Alyssum sp., Biological cycle

Jan 1, 2003

By R. C. Nascimento

It was investigated the effect of the addition of bentonite on the physical propertiesof pellets produced from fines of manganese ores. Cold-bonded pellets were produced. Pellets bearing up to 1 wt% of bentonite were submitted to strength compression resistance tests, fatigue of pellets to impact and maximum height of fall tests. A correlation of resistance of the pellets and time for curing were stablished. The produced pellets match the conditions for raw materials used in electric smelting hrnaces to produce manganese based ferro-alloys.

Jan 1, 1995

By G. Cifuentes

It's know that the cathodic purity and the electrolyte treatment is affect for the solid present in the electrolyte. Anodic slimes properties (f.e.: chemical composition, crystalline composition, sedimentation) was studied in copper electrorefining, this properties were modify through by anodic composition and current density. In this paper will be present only the preliminary anodic slimes relationship at different lead anodic composition. The anodic material was doped during the poured process with lead at different composition. It's confirm the apparition of the (Bindheimitte) SMbz07. The specific gravity of this specie is approximately 7.3 - 7.5, with this values is biggest the probability of sedimentation and smaller the slimes not sedimentabel.

Jan 1, 1999

By W. Kunda

A laboratory study was carried out on the treatment of sulphidic copper concentrates in aqueous chloride systems under elevated temperatures and oxygen overpressure. Exploratory tests showed that chalcopyriteoxidizes with various chloride salts to form, depending upon the pH of the system, soluble copper chloride or insoluble copper oxychloride salts; the copper can then readily be recovered from the solution or residues respectively. During the leaching, iron was oxidized to iron oxide and remained in the leach residue while the bulk of the sulphide sulphur was oxidized to the elemental form with a minor portion oxidized further to sulphate. The presence of metal chloride salts in the system increased the oxidation rates of chalcopyrite and depressed the solubilization of iron in the system. A systematic oxidation leach study carried out in (1) ammonium chloride and (2) sodium chloride systems showed that the former system required little or no HC1 addition while the latter required 2 mol of HC1 per mol of dissolved copper (plus zinc). The copper was recovered from the cuprous or cupric chloride leach solutions by cementation with iron. Extractions of 99% copper and zinc, 97% silver, and negligible iron were obtained. Sulphur was oxidized to the elemental or sulphate form; the relative proportions of the total sulphur were 60 and 30% for system (1) and 80 and 10% for system (2). A flowsheet for a conceptual process with minimal reagent requirements was proposed.

Jan 1, 1976

By C. Peter Hayes

The world continues to change and with it the supply of minerals and metals, the location of centres of production of primary metal and the increasing levels of metals and materials recycling. New technologies are being developed to meet the ongoing search by industry for lower costs, cleaner production and new markets. To keep abreast with these changes, and to utilise fully, the potential benefits of these technical advances, the industry will need a professional workforce having different knowledge, skills and professional attributes than in the previous millennium. What are these skills and attributes? How to best attract and develop the metallurgists of the future, and provide for the ongoing educational and research needs of the industry?

By S. L. Pohlman

Physical characteristics of possible importance in the acid leaching of Chrysocolla have been evaluated. Surface area studies and pore size distribution indicate: 1) a large surface area (350 m /gm); 2) an average pore size of 13 or 16 Å , depending upon use of the adsorption, or desorption, branch of the Type IV isotherm in the evaluation; ) the presence of a significant fraction of pores of size less than 15 Å determined by the accumulation surface area method. The initial structure is micro- crystalline on the basis of x-ray powder patterns; the silica leach residue is amorphous and has only 24 m2 /gm surface area, and loses integrity when dry. However, readsorption of copper onto the wet leach residue gives a product with integrity and 100 m2 /gm surface area. Visual observation of the leach residues supports evidence of a non-protective diffusion mechanism of leaching which is well correlated by the shrinking core model previously presented.

Jan 1, 1976

By I. M. S. Moraes

Caraiba Metais has a plant for the purification and the cristallization of the crude nickel sulfate removed from its copper electrolyte purification system. In November 1994, an interdepartmental group was formed to study the Q.F.D. method, through its application on the improvement of the quality of the nickel sulphate hexahydrate. The team, formed with representatives of the following areas : production, technology, marketing, sales, maintenance, laboratory and TQC office, had also the task of checking the applicability of the method to other products of the comp any. This paper describes the main steps such as the survey of customer's demands, the preparation o1 the quality matrix, stablishing the planned quality matrix, the planned and the designed quality, and the consequent identification of the engineering bottlenecks. It is also shown how these bottllenecks were studied and solved. The application of the method allowed the team to identify means of increasing the production capacity by 40%, to improve the intrinsic quality of the product (including packaging), and to increase the reliability of the process.

Jan 1, 1997

By Lloyd Robert Nelson

The historical progression in installed electric furnace smelting capacity of some 1650 calcium, chromium, manganese, nickel and silicon ferro-alloys furnaces is reviewed. Key increases in the inherent installed electrical capacity, often achieved through uprating furnaces, are identified. Possible factors facilitating such advances are explored, including: specific process engineering and pyrometallurgical enhancements (e.g., improved control over the consistency, size and chemical form of raw materials, extents of preheating and pre-reduction delivered into the furnace; and patterns of feed distribution); furnace electrical configuration (AC or DC; immersed, submerged-, shielded- or open-arc); form of electrode (graphite, self-baking or composite); furnace configuration (circular or rectangular; closed or open and 1-, 3- or 6- electrodes); better engineering and equipment designs (e.g., high-intensity cooling) and state of furnace electrical and metallurgical control systems. A view is presented on the prevailing state of evolution of the Mega-scale in ferro-alloy smelting and opportunities for still further improvements.

Jan 1, 2014

By Arpad E. Torma

The identification and characterization of lithographic iron and sulfur oxidizing bacteria in the 1940' s. opened up new possibilities and challenges for the mining and metallurgical industries. These were exploited during the 1950's and' 1960's, when it was demonstrated' that mining wastes and complex unused mineral resources could be economically treated by bacterially assisted heap and dump leaching processes?. During the 1970's this technology grew into a more structured discipline called "biohydrometallurgy". In the l980's efforts were devoted to the identification of a variety of organisms involved in naturally occurring leaching processes. Further efforts dealt with the elucidation, of leaching mechanisms; the leach ability of nickel, coban, zinc, and precious metals; the desulfurization of coal; and diverse biosorpion phenomena. The application of genetic engineering techniques for the improvement of microbial performance was also initiated?. Current trends in biohydrometallurgy include improvement of many of the techniques noted above, as well as application of leaching. technolog.ies to. environmental remediation scenarios. These activities afford considerable opportunities for research in the 1990's. For example, bioremectiation of abandoned mining and processing sites requires development of new and economically viable technologies capable of removing low concentrations of toxic metals from high volumes of solid and/or liquid wastes.

Jan 1, 1991

By Daniel K. Lindberg, Fiseha Tesfaye

To reduce the use of fossil fuels and increase self-sufficiency in energy, nowadays, there is an increasing interest to produce heat, power and transportation fuels from renewable resources. Solid biomass is one of the most important renewable energy sources for meeting this target. However, fouling, slagging, and corrosion threaten long-term operation availability and costs of biomass power plants. Slags accumulated on the surfaces of superheaters, which decrease thermal efficiency, often constitute a considerable percentage of complex inorganic phases. However, thermodynamic properties of the complex inorganic phases and their combined effect, which will help to deal with the slag related problems during high-temperature biomass combustion processes, are not well known. In the present paper, thermodynamic properties of K-, Ca-, and Na-based inorganic phases and their mixtures under different gas conditions are both critically reviewed and experimentally studied. The obtained results are presented and discussed.

Mar 1, 2017

By Fernando Aracati Botelho, Jose Antonio Silva Souza, Luis Alves Venancio, Emanuel Negrão Macedo

"1 AbstractThe production of alumina from bauxite using the Bayer process generates 0.7 to 2.0 ton of the residue known as red mud and about 800 kg of CO2 per ton of alumina. The direct use of exhaust gases to react and neutralize the bauxite residue may allow a double gain: open a wide range of new applications for bauxite residue reducing its reactivity and sequester from 3 8 to 107 kg of CO2 per ton of alumina. This paper shows a pilot scale reaction of a suspension of bauxite residue-water with flue gas produced from direct burning oil, similar to the exhaust gases of a refinery. Two different types of reactors are used, a spray tower and a packed column. The inlet and exhaust gases are analyzed using electrochemical cells and non-dispersive infrared sensors. The pH of the suspension is monitored during the reaction and after to evaluate the buffer effect. 2 IntroductionThe production of millions of tons per year of alumina around the world generates from 0. 7 to 2.0 ton of the residue known as red mud (RM) per ton of alumina. The vast majority of the red mud is stored in large sealed lakes. Due to the high reactivity this material is considered dangerous and currently there is no operating process capable of reusing all the material produced at any refinery. These lakes after filled of solid material eventually have the surface revegetated [4]. In any case they will remain as an environmental passive and needs monitoring for decades. The search of a industrial process that combines the reduction of the CO2 emission and the reduction the pH of the red mud opening the possibility of large scale and economically viable ways is the main objective of this work.The use of the exhaust gases of the refmeries to neutralize the bauxite residue may allow a double gain: Open a large array of new applications for the residue with the reduction of its reactivity and sequester millions of tones ofCO2 plus other gases like SO2 [7] and NOx. This project studies the reaction of the exhaust gases from a boiler burning diesel with RM in different reactor types and conditions in order to obtain parameters to design equipment capable of process this reaction on a larger scale. With these objective compositions of red mud were processed with flue gas at concentration similar to the exhaust gases of the calcination process and boilers of the refmeries."

Jan 1, 2012

By John T. Berry, Robert D. Pehlke, Michael J. Beffel

"Pattern making and metal casting organizations are currently adopting CAD/CAM systems and implementing this technology in design and production. Al though significant progress has been reported, these systems generally are based on two or two and one half dimensional analyses. Very few are based on solid geometric modelers.The present paper emphasizes the need for solid geometric modeling of the casting and rigging system and linkage with a solidification simulator. The nature of some of the technological challenges which have slowed this development are discussed, including accurate description of complex surfaces and their intersections and the bridging of computer encoded information with NC technologies and with FEM-based simulators for stress and thermal analyses. A recently prepared modular-structured FEM simulation code implemented on a micro computer is described.Construction of a solid geometric model of the casting and rigging and validation of the combination for optimum characteristics of soundness, quality and yield by solidification simulation are I inked as key elements in the foundry of the future. Data base support for this CAD/CAM system is rapidly being developed throughout the world.INTRODUCTIONThe simulation of shaped casting solidification using the digital computer, goes back to at least the early nineteen-sixties when Forsund (1) in Denmark applied the technique to the problems of casting surface quality.Prior to that time, the work of Paschkis and co-workers using the analog computer ranges back to the nineteen-forties, when work sponsored by the AFS Heat Transfer Committee at Columbia University revealed many hitherto unknown or only partly anticipated aspects of casting solidification (2).Three reviews of the various historical aspects of simulation should be referenced. Firstly, the AFS monograph by one of the present writers (RDP) and his colleagues - describing background and later work, again sponsored by the AFS Heat Transfer Committee at the University of Michigan (3). Secondly, a review prepared by Durham and Berry (4) which discusses broad aspects of casting solidification simulation. Thirdly, a review by Erickson (5) which contains an excellent bibliography to 1980. In addition to these papers, the publications lists of the CADCAST project* and the proceedings of the two Engineering Foundation Conferences of Casting and Welding Modeling, published by ASME, are also most notable (6) •"

Jan 1, 1986

By Frank A. Stephens

The process of converting iron ore (principally Fe,03 or Fe30,) into iron carbide (Fe,C) to be used as feedstock for steel-making yields complex mixtures of several Fe-containing compounds as a function of processing conditions. In addition to the above compounds (hematite, magnetite and cementite), the mixtures typically contain wustite (FeO) and metallic iron(Fe). Mossbauer spectroscopy has been developed into aquantitative analytical method for monitoring the degree of conversion to carbide from samples periodically extracted from a fluidized bed reactor type of pilot plant. Calibration of absolute quantities of the above five compounds is based on standards prepared from known mixtures of the high purity individual phases. The PC-based spectrometer allows fitting of the well-known spectral components of each of the five phases, the resulting spectral areas then being compared with the calibration curves via PC software to yield the weight fraction of each. Emphasis has been placed on standardizing and simplifying the analysis procedure for routine use in an industrial environment.

Jan 1, 1993

By Kazuyuki Kikuta

MMAJ, a govemmental organization in Japan, has carried out a 4 year project for the development of the decontamination and metals recovering technology for the fly ashes from municipal waste incineration. Heavy metals (zinc, lead and copper) are recovered as raw materials for the non-ferrous metals production, without formation of any waste materials to be disposed. More than 500 thousands tonnes a year of fly ashes generation from the municipal waste incineration has been one of the main social issues in Japan, because most of them need to be disposed to the registered areas after decontamination, and occupy 5% of the municipal wastes disposed. The segregation, flotation and chemical process are applied to the treatment of the primary fly ash from municipal waste incineration, and MF (Mitsui-type blast furnace) Process after the chlorine removal to the secondary fly ash. The main results of experiments are -About 90% of heavy metals, zinc, lead and copper, can be recovered from the primary and the secondary fly ashes to the products for the non-ferrous metals production. -Both of the leaching residue from the primary fly ash treatment and the slag from the secondary fly ash treatment can be used as a raw material for the cement production, meaning that the decontamination technology for the ashes without the landfill has been established. -Dioxins in the primary ash can be decomposed satisfactorily, and the dioxins content in the segregation furnace gas is less than O.lng-TEQ/Nm3 without any gas cleaning system

Jan 1, 2003

By Adrien Antenen, Didier Villette

CITRON has developed a new process for the recycling of hydroxide sludge, household batteries, catalysts, automobile shredding residues, grinding sludge and other metal containing organic and inorganic waste. A pilot plant with a capacity of 1,000 tons per year has started operations in April 1998. In August 1999, an industrial plant became operational with an initial treatment capacity of 23,000 tons.

Jan 1, 2000

By C. S. Griffith

Lithium Australia NL (ASX:LIT) and ANSTO Minerals have been working together since 2015 on the development of halide accelerated leaching for the extraction of lithium from lithium-bearing micas, spodumene and clays. This technology has been termed SiLeach® process. The driving force behind development of the SiLeach® process, initially, was to develop a hydrometallurgical process to extract lithium from micas and spodumene without the need for the energy intensive, high temperature processing conventionally applied to lithium extraction. This driving force remains today and continues to hold promise in realising the value of previously under-utilised lithium resources. A comprehensive understanding of the technology and its applicability to the processing of micas and spodumene currently exists, and the flowsheet has been rigorously piloted. Production of battery grade lithium carbonate has been demonstrate

By Jong-Jip Kim, J. G. Byrne, W. Kim, In-Ok Shim, John E. Flinn

"Two rapid solidification processes for 304 stainless steel were studied: centrifugal atomization (CA) in a helium atmosphere and atomization by exposing argon-containing melt to vacuum (VGA). Positron annihilation and x-ray line broadening measurements of explosively consolidated monoliths were used to clarify microhardness measurements as a function of annealing temperature. Interesting differences in positron response between CA and VGA materials are ascribed to more carbide formation in the CA material than in the VGA material in the 600 0C range. In addition, hot isostatic pressing of the CA material was examined as to the relations between mechanical behavior, pore shape, and relative density. A variable stress concentration factor is introduced into the theory to allow for changing pore shape as relative density increases.IntroductionThere are many potential advantages of rapid solidification processing (RSP), such as a high degree of matrix supersaturation, finely dispersed microstructures, improved chemical homogeneity, and retention of metastable phases, which have been studied extensively. To consolidate rapidly solidified material which is in powder form into useful shapes often requires subjecting the material to elevated temperature for extended periods of time under mechanical forces, as in hot isostatic pressing or hot extrusion. In such cases, some of the characteristics of the rapid-cooling step can be strongly affected. An alternative is dynamic consolidation (1), for example by explosive forming, where the time frame at least is extremely short.In the present work, effects of the consolidation processes of hot isostatic pressing (HIP) and explosive forming in a die are examined. The particular material is 304 stainless steel. The characteristics of both RS and VGA 304 stainless-steel powders were described by Wright, Flinn, and Korth (2) earlier."

Jan 1, 1988