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By Robert L. Opila

Negative electrodes for alkaline nickel-metal hydride batteries composed of MmNi3.5Al0.8Co0.7, where Mm is misch metal, have been characterized electrochermically and using x-ray photoelectron spectroscopy. The stability and rapid hydriding and dehydriding kinetics of the alloy in KOH are attibuted to a surface film. The protective surface film is shown to consist of an porous, outer hydrated layer and a dense, inner oxide layer. In addition, metallic nickel and cobalt are found throughout the film, and are presumed to form a conductive, percolative network that permits rapid electron transfer from the bulk to the solution, allowing rapid electrochemical formation of atomic hydrogen.

Jan 1, 1997

By D. D. Rodier

Most zinc concentrates contain some silver and varying amounts of such valuable trace elements as gold, indium, germanium and gallium. With increasing similarities in plant installations, the predominance of electrolyte process and the increasing environmental constraints on iron disposal, it is essential that zinc smelters optimize the recovery of any valuable elements in their feed stocks. The process options, to date, of smelting, flotation or leaching of silver-rich leach residues cannot be applied economically to all installations. It is therefore necessary that new innovative processes, to recover silver and other valuable metals from relatively low grade feeds, be developed. This paper attempts to place this strategy in the context of today's constraints and will also provide a simple evaluation tool for any process alternatives.

Jan 1, 1990

By Rajashekhar Marti, York R. Smith

Lithium is anticipated to be a key, strategic material in the clean technology economy. The majority of lithium reserves are contained in continental brines and sea water (>60%). Currently the most economical approach to recover lithium from such resources is through selective adsorption. Spinel type lithium manganese oxide and lithium titanium oxide have demonstrated to be excellent candidate materials (after de-lithiation). However, due to the small size of the powders, they have limited industrial application and require immobilization. In this work, we examine the application of novel manganese oxide nanowire composites for the extraction of lithium from dilute solutions. Manganese oxide nanowires were synthesized and simultaneously immobilized on diatomaceous earth via hydrothermal method. Lithium manganese oxide were then formed by solid-state reaction, de-lithiated and tested for lithium ion adsorption.

Mar 1, 2018

By K. Narayana Swamy

Experimental results of 3-phase mixing in a physical model of a CCRL for metals refining, at high levels of bottom gas injection (up to a superfIcial gas velocity (Us) of 12.5 cm/min), are presented. A thermal tracer technique was used to elucidate both longitudinal mixing and interphase heat transfer. The results indicate that even under conditions of significant bottom gas injection, it should be possible to maintain acceptably low longitudinal mixing (D. < 20 cm2/s and D/uL < 0.1) in the CCRL. Interphase mass-transfer coefficients of the order of 0.02 cm/s and higher, are predicted from the measured interphase heat transfer coefficients using the mass and heat transfer analogy. Adequate performance is likely to be possible for an industrial CCRL, based on extrapolation of these results to full-scale conditions.

Jan 1, 1996

By Ji-He Wei

The ESR of Cu-Cr-Zr alloy has been experimentally investigated. The remelting experiments have been carried out with different slag fluxes in the Cal, + Nal, CaF2 + ZrO2 and CaF2 + NaF + ZrO2 systems on an ESR furnace of 25kg capacity; using a water-cooled copper mould of 96.5 mm diameter, with the forged square bar electrodes of 50x50 mm2. The slag amount was taken to be 1.5 kg. The remelting current and voltage used were 1600-1800A and !5-25K, respectively. The influence of the slag composition on the stability of the remelting process and the losses of alloying elements (2r and Cr) has been considered and examined. The technologies of hot working and heat treatment of the ES ingot have been described and discussed. Some physical properties of the slag in a CuF2 + NaF + ZrO2 system and the remelted Cu-Cr-Zr alloy have been determined. The results indicated that with the slag flux of CaF2 + NaF + l0 mass % ZrO2 and the other operation parameters employed, a high quality ingot of Cu-Cr-Zr alloy may be obtained at the considerably high yields of Zr and Cr by means of ESR. For the remelted Cu-Cr-Zr alloy with a specified composition of 0.5 mass % Cr and 0.1 mass % Zr, the appropriate electrical conductivity, hardness and softening temperature are as high as 45-46S/m, HRB 82-84 and 550°C. respectively. The properties of the Cu-Cr-Zr alloy products are in accordance with and superior to the requirements and specifications of ISO5l82-l99l(E).

Jan 1, 2000

By E. N. Mounsey

Ausmelt Technology was selected by Bindura Nickel Corporation (BNC) as the basis for a new copper circuit to process nickel plant copper leach residue to blister, anode and finally cathode copper and recover PGM values at the Bindura Smelter Refinery (BSR). The process selected, based on Ausmelt Technology to smelt and convert the residue to matte and blister copper and produce a discard slag, is novel incorporating smelting, converting and slag reduction process steps in a single Ausmelt vessel. The process demands a high quality blister copper product with low levels of arsenic and nickel. This paper reviews the project and the initial operational results to the end of 1997 of the Ausmelt Top Submerged Lancing (TSL) smelter and discusses the implications for the wider TSL converter market.

Jan 1, 1998

By A. J. Williams, T. N. Croft, M. Cross

"The computational modelling of extrusion and forging processes is now well established. In this work a novel approach is described which utilises finite volume methods on unstructured meshes. This technique can be used to solve simultaneously for fluid flow, heat transfer and non-linear solid mechanics and their interactions. The approach involves the solution of free surface non-Newtonian fluid flow equations in an Eulerian context to track the behaviour of the workpiece and its extrusion/forging, and the solution of the solid mechanics equations in the Lagrangian context to predict the deformation/stress behaviour of the die. Some preliminary examples of this approach will be discussed.IntroductionThe computational modelling of extrusion and forging processes is now well established. Within the last 20 years the finite element method has become the most commonly used technique to simulate metal forming processes [1]-[4]. The Lagrangian and Eulerian type of formulation have been the two major approaches to this problem.Lagrangian methods are efficient and suitable for handling non-linear problems in which small strains prevail, boundary conditions do not change with the course of deformation, and where mesh distortion is not a critical factor in the analysis. Unfortunately, the above points are essential to any accurate metal forming analysis. The problems of mesh distortion and element entanglement pose a serious drawback on the use of such methods. Some automatic remeshing techniques have been developed for Lagrangian finite element analyses of metal forming problems [5]-[7]. However, these methods are not robust and efficient enough to remedy the mesh distortion problems in general. An alternative is to update the mesh manually but this is not always possible, and even when it is feasible it involves major interaction by the user. In addition, remeshing is usually applied to the whole domain which is not necessary and increases CPU time. The complexities associated with remeshing also affect the ability to parallelise the code."

Jan 1, 2001

By Liang Sha

In this study, adsorption of copper by chemically modified orange peel was investigated. A conspicuous change occurs in the surface morphology of the biomass due to modification, which is depicted by SEM images. Equilibrium isotherms and kinetics were obtained and the effects of various factors, including solution pH, contact time, initial metal ions concentration and temperature, were studied by batch experiments. Kinetics was found to be best-fit pseudosecond- order equations. Equilibrium was better described by Langermuir isotherms rather than Freudlich isotherms. At 25?, pH5.30, the maximum adsorption capacity was 70.67mg?g-1 . With increase of temperature, adsorption efficiency decreased. The biosorbent was suitable for repeated use for more than five cycles.

Jan 1, 2009

By Richard A. Heckman

Destructive Thermal Technology (DTT) is used in the management of various waste streams. DTT includes Destructive Distillation, Pyrolysis and Classical Incineration. Recent work has more clearly defined the differences in these technologies based upon a more rigorous thermochemical approach. The U.S. Environmental Protection Agency (EPA) has chosen Classical Incineration as the Best Developed Available Technology (BDAT) for the management of hazardous organic wastes. Municipal Solid Wastes (MSW) and Sewage Sludges (SS) are also managed using Classical Incineration. Three environmental problems plague the use of Classical Incineration. Destructive Distillation, on the other hand, avoids these problems. It is an environmentally benign DTT for managing a wide variety of organic waste streams, including hazardous wastes. Thermochemical analysis of the available data on the performance of three types of DTT will be discussed.

Jan 1, 1994

By Tullio Corsini

Scrap battery recovery process, developed by Engitec Impianti S.p.A., is improved transforming batches operations in continuous. Benefits expected: constant and better quality of the products; easier and more reliable control of the operating parameters, reduction of manpower requirements. Paste will content less sulfate, particularly in soluble form. Sodium sulphate is obtained with higher and constant purity.

Jan 1, 1993

By Derek J. Fray

"A need exists for fast and accurate analysis of species in various phases at elevated temperatures. Although modern analytical techniques are very efficient, the equipment is usually situated some distance from the industrial operation and time is spent taking the sample and sending it to the analytical facility. Several minutes can easily lapse and, during this time, heat must be supplied in order to keep the system molten and, if the composition is changing rapidly due to a refining process or reaction with the environment, the information may only be of retrospective use. Perhaps more important reasons for the use of on-line sensors are that instantaneous analysis gives better control, process optimisation and the minimisation of energy losses and pollution. To date oxygen has been the only element which is measured widely using solid electrolytes. However, the analysis of many more elements is required and possible electrolytes for other species are discussed. For some elements, ~here is no suitable conducting electrolyte and, therefore, a different approach is adopted where the electrolyte, in which one species is mobile, comes to equilibrium with another species. IntroductionThere is an ever increasing demand for the development of sensors for on-line measurements in most areas of technology and, in particular, metal processing. This is especially relevant in situations where greater control can be achieved by monitoring the chemical composition of the melt during processing and where a minor constituent in the melt can have a major effect on the properties of the finished alloy. Although modern analytical techniques are fast and reliable, the equipment due to its complexity, is frequently situated away from the process area and valuable time may be spent in sampling and transportation. During this period, heat may have to be supplied to prevent solidification and the refining reactions may be continuing, and, therefore, the analytical information may not be of direct use."

Jan 1, 1988

By R. J. McClincy

The potential techniques for the direct smelting of copper sulfide concentrates to blister copper were evaluated from the standpoint of commercial application. Many existing smelters are adaptable to direct smelting practice but only with improved control of metallurgical performance. Modified and innovative procedures for slag cleaning and metal refining, prerequisites to direct smelting, are presented and discussed. The ability to smelt directly to blister copper using existing equipment and eliminating the need to convert matte offers ,significant advantages to traditional smelting practice from the viewpoint of cost, &apos;S02 control, and process simplicity.

Jan 1, 1983

By Ali Akbar Mottahedi

Chromate conversion coating is a process for making a complex layer at the surface of zinc galvanized steel which makes the metal more resistant to corrosion, especially at marine atmosphere, and increases the adhesiveness of color. In this work the influences of various compositions on commercial zinc galvanized steel sheet to the color of chromate conversion coating has been investigated at normal temperature and the factors that affect the control and optimization of the process have been determined. A bath composition of 20 g/liter Cr203 and 10 g/liter NaOH and a dipping time of 50 seconds at room temperature (25-30°C) make a desirable color of chromate coating. A slow agitation at a constant pH of I (with additions of NaOH or H2SO4) assures a constant bath condition and develops the color. This kind of coating has more corrosion resistance and this bath condition and composition are also more economical.

Jan 1, 2003

By P. J. Mackey, J. B. See, D. G. C. Robertson

The production of iron and steel and non-ferrous metals by pyrometallurgical processes will remain a critical element in meeting the demand for materials in both developed and developing nations. Given the important need to reduce and minimise greenhouse gas emissions the technological focus of future pyrometallurgical R&D by universities and industry alike must concentrate on sustainability issues such as improved energy efficiency, recycling and waste minimization. Continued efforts are also needed on process optimization and new process development with a view to reducing capital and operating costs of the new large “mega” plants. Using the academic and industrial backgrounds of the authors, the present paper reviews the current status of R&D in pyrometallurgy in university departments with a particular emphasis on sustainability issues. The role of industry and government laboratories is also reviewed although primarily for developed countries. The paper also includes comments and suggestions on the future requirements for education and R&D in pyrometallurgy in developed countries to maximise sustainability. It is also suggested that future R&D in pyrometallurgy will be even more concentrated in developing countries – most notably China.

Jan 1, 2014

By A. Elizabet Serna

The weak acid is a by product obtained in a pre-treatment of gases from a copper smelter prior to sulfuric acid manufacture and the main components of this weak acid are: sulfuric acid. copper, arsenic. antimony, bismuth and iron. Usually, this effluent is neutralized with lime and the solid residues are stored in a landfill as a hazardous waste. This work was directed at determining the optimal conditions to recover copper from weak acid using a cementation process before the neutralization of the effluent. The variables investigated are: Effluent temperature, iron scrap amount and acid concentration versus reaction time. The results of these experiments show that the cementation process of copper and the co-cementation of impurities such as arsenic, antimony and bismuth were in accord with the theory of the electrode potentials.

Jan 1, 1996

By Berndt Moeller

Mercury-cell chlor-alkali production plants generate mercury contaminated wastewater streams from which mercury must be precipitated and filtered, resulting in a sludge containing 2% mercury (designated KI06) that cannot be landfilled in the United States without treatment. REMERC is a chemical treatment process used to recover 99% of the mercury from wastewater sludge generated at these plants. The process uses leaching to oxidize mercury compounds to mercuric chloride, washing and filtration to separate mercuric chloride from the treated sludge, and cementation to reduce the mercuric chloride to metallic mercury. Mercury not recovered in cementation is recycled to the wastewater process for precipitation and filtration. Treated sludge contains less than 260 ppm total mercury and 0.2 ppm TCLP, meeting the USEPA low mercury subcategory specifications that allow landfill disposal. REMERC uses readily available chemicals, is straightforward to control and inexpensive to operate, has no mercury emissions to air, and recovers metallic mercury. REMERC enabled significant cost savings including lower solids disposal costs, recovery and reuse of metallic mercury in the chlor-alkali process, and ability to treat non-wastewater sludge. No new EPA permits were required. REMERC was shown to be a viable process for recovery of metallic mercury from K106 designated sludge.

Jan 1, 2003

By Peter G. Mason

Over the last 15 years numerous Pressure Oxidation and Pressure Leach plants have been installed throughout the world. The technology is no longer regarded with awe and trepidation as plants designed to treat a wide range of feedstocks continue to be successfully brought on line. Important aspects of the design of such plants include feed preparation, slurry pumping, heating and heat recovery, pressure control and let-down, vessel design, safety and provision of associated services.

Jan 1, 1999

By Makoto Suzuki

After hot rolling, stainless steel strip is processed by the Hot Rolled Annealing and Pickling line (HAP) , where H2SO4 or mixed acid of HNO3 and HF is normally used. In the pickling bath, metal oxide accumulates in the form of sludge, which should be removed from the bath regularly. A new automatic continuous sludge disposal system has been introduced at Chiba Works of Kawasaki Steel Corporation to increase sludge removal efficiency and improve the working environment. The elements of the equipment are as follows. a. Ejectors in pickling bath: to carry the mixed acid into the circulation tank through the piping system. b. Sedimentation bath : to sediment sludge out of the bath. c. Skip conveyer : to convey a specified volume of sludge into a kneading for device for neutralizing. The sludge removal efficiency of this system is very high. and the volume of sludge accumulation in the pickling bath has substantially decreased.

Jan 1, 1996

By Yasuo Kudo, Wu, Hayato Sato, Hiroshi Nakazawa, Shouming

"In order to recover copper from a waste nickel condenser powder, bioleaching experiments were carried out using Thiobacillus ferrooxidans in a shaking flask. The content of nickel and copper in the waste nickel condenser powder in this study were 8.0% and 3.5%. X ray analysis showed the peak of barium titanate. In the preliminary study using metal nickel and copper powders , the dissolutions of nickel and especially copper were accelerated with the addition of ferric iron in the bioleaching of nickel and copper powders while not in the absence of ferric iron. Ferric iron oxidizes both metals, and Thiobacillusferrooxidans oxidizes ferrous iron resulting from the oxidation of metals, whereby the dissolutions of metals proceeds. The dissolution rates of nickel and copper increased with increase in the concentration of ferric iron in the bioleaching of the waste nickel condenser powder.1. IntroductionNickel condensers rejected from manufacturing plants are crushed and landfilled. Waste nickel condensers contain nickel and copper and could be considered as nickel and copper ores. Since the capacity of landfills is diminishing, it is required to recycle metals of waste nickel condensers in order to reduce the amount of wastes landfilled. Conventionally, metals in the waste were recovered by dry metallurgy after the incineration.Nickel has been refined by solvent extraction - electrowinning method (SX-EW method). Recently the amount of copper refined by SX-EW method has increased (Takahashi, et al. 1994). This method is cleaner and consumes less energy than conventional methods. Nickel dissolved well in acid solutions, but copper is not. If copper is leached efficiently from a waste nickel condenser powder, SX-EW method will be applied to recover copper from them"

Jan 1, 2000

By J. Rajesh Kumar

The extraction equilibrium study of tetravalent platinum was carried out using tri-octyl/decyl amine (Alamine 336) and bis(2,4,4-trimethylpentyl) monothiophosphinic acid (Cyanex 302) in kerosene from hydrochloric acid media to investigate their extraction capacity, since they have different donor atoms, ?N? and ?S?. Their distribution equlibria were studied as a function of acid, extractant, diluents and temperature. The title metal shows the inverse behavior at higher acid concentrations. Extraction of tetravalent platinum increases with increase of extractant concentration. The plot of log D vs. log [Extractant], mol.L-1 is linear with slopes 1±0.3, indicating the association of one mole of extractant with the extracted metal species. Stripping of metal from the loaded organic (LO) with mineral acids and bases such as hydrochloric, sulphuric, nitric acids and ammonia, hydrogen peroxide, sodium hydroxide, thio- urea were studied. Regeneration and recycling capacity of Alamine 336/Cyanex 302 and extraction behavior of associated elements was also studied.

Jan 1, 2009