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By Donna L. Bodine

The ability of oxidized Upper Freeport bituminous coal to adsorb Cu2+, Cd2+ and Mn(VII) from very dilute aqueous solutions has been studied. Low-rank coal is known to adsorb heavy metal ions from dilute, aqueous solutions, probably by ion exchange and/or chelation by acidic functional groups on the coal surface. However, it would be advantageous to use higher rank coals for water treatment. Coal samples were oxidized thermally or by 30% H202 to increase the surface concentration of phenolic and carboxylic groups, then portions were shaken with Cu2+ and Cd2+ solutions. Acidic KMnO4 was also used to oxidize coal, with concurrent sorption of the resulting Mn(IV) and Mn(ll). The effect of oxidation treatment, metal ion concentration, and solution pH on metal uptake kinetics was investigated. Potential applications for treating effluents, especially those containing oxidizing ions, are discussed, along with possible flowsheet options.

Jan 1, 1995

By I. A. H. Schneiderl

Eichhornia crassipes approaches being a scourge in many parts of the world, .choking waterways and hindering transport upon them. At the same time it is known to readily abstract heavy metal ions from water and, thus, aids in the removal of heavy metals found in such waters. This paper considers the possibility of using specific parts of the plant as an inexpensive adsorbent for the removal of heavy metals from contaminated chemical and mining industry waste waters. In particular the root of the plant was found to be an excellent accumulator of 'heavy metal ions including uranium from solution. It is. also suggested that dried roots of the plant ?might be placed in simple bags and used in a very low cost metal ion removal system.

Jan 1, 1995

By John J. Mortvedt

Application of some by-products of the metals industry which contain plant nutrients to agricultural lands could constitute resource recovery instead of costly disposal. Some industrial by-products contain appreciable concentrations of heavy metal contaminants, such as Cd, Cr, Ni, and Pb. After land application, these metals may be absorbed by plants and enter the human food chain or be leached to groundwaters. Plant uptake of these heavy metals varies with plant species:, soil pH, soil texture, and the particular metal. Certain leafy vegetables can absorb significant amounts of heavy metals, while absorbed metals are usually poorly translocated to cereal grains. Allowable heavy metal concentrations in fertilizers now are not regulated, but EPA is considering such regulations. Heavy metal impurities in animal feed supplements are regulated by the states; so some by-products may not be permitted for this use.

Jan 1, 1992

By Mick O'Meara

Metal Organic Chemical Vapour Deposition (MOCVD) is used in the production of computer circuit boards and metal shapes in nickel, gold, copper, cobalt, etc. All varieties of .MOCVD use the decomposition of a vapour of organometallic compounds to produce different forms of ultra-pure metals, or alloys. CVD Manufacturing's proprietary MOCVD process has been adapted and developed to produce commercially ultra-pure metal shapes, metal powders, and metal foams. Therefore, it is a purification process. The typical process has three steps. First, a volatile metal organic compound is produced from volumetrically contaminated metals, metal oxides, etc. Typical feed materials are metal powders, ores, concentrates, or a slurry of metals and contaminants. Secondly, the volatile. metal organic compound is purified by fractional distillation. Thirdly, the purified metal organic compound is decomposed into different forms of ultra-pure metals, such as net shapes, powders, or metal foams. A mixture of metals can be purified either by the selective production of volatile materials, or a separation can be achieved during the second step, in the fractional distillation stage. The purification and recycling of metals by the MOCVD process will be discussed, particularly with regard to nickel, aluminum, gold, the platinum group and other metals.

Jan 1, 2000

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 Mark Cross, Andrew P. Campbell, Koulis A. Pericleous

"Computational Fluid Dynamics (CFD) modelling is being used to simulate the freeze layers formed within direct smelting processes. There has been some concern whether water-cooled elements can withstand the p~ocess conditions and in particular abnormal cases where they may be splashed in molten metal.To validate the models being developed, two cases from literature have been modelled for solidification and stress analysis. The solidification case is presented in detail and is for hot molten metal flowing through a cylindrical pipe. The walls are at a temperature below the melting point for the metal. The resulting solid (or freeze) layer is within 3% of the value calculated by Sampson & Gibson9 •Preliminary modelling of the refractory-slag interactions is presented. Although three basic mechanisms: Penetration; Corrosion; and Erosion will eventually be modelled, only the penetration is considered here. The corrosion mechanism is to be modelled by tracking the time that the penetrated refractory is at the required temperature.Future work, after adding all the required physics, will focus on the modelling of a water-cooled element placed lower in the smelter. Process perturbations will be simulated to examine what these elements will withstand."

Jan 1, 2001

By R. G. Haire

Studies of the f-elements under pressure provide important insights into their solid state chemistry and physics. From such studies, of the elements and their alloys, it has been established that the normally localized f- electrons of several of these elements can become, involved in bonding under pressure. The electronic behavior of f-element compounds under pressure tend to be more difficult to interpret, due to the variety and the nature of electronic orbitals that are present. The 4f-elements and some 60% of the 5f-elements have been studied under The systematic comparisons that have been established for these materials are discussed.

Jan 1, 1992

By S. G. Galbraith

We have used the principles of supramolecular chemistry to develop reagents to transport metal salts. These reagents have separated charged "compartments" which recognize a metal cation and its attendant anion(s). They are easy to manufacture as they are structurally related to the commercial hydroxy-oxime extractants for copper. Efficient protocols for loading and stripping of these extractants depend on the novel feature that they bind the metal salt in a zwitterionic form of the ligand. Transfer of the phenolic protons to the pendant amines generates the charged "compartments" to accommodate the metal cation and its attendant anion(s). This paper focuses on how these types of reagent can be used to recover base metals from sulfate and chloride media in flowsheets in which solvent extraction effects separation and concentration operations, interfacing between conventional leach and electrowin/reduction processes. Work on the development of reagents that have high selectivity for metal chloride/sulfate transport, convenient stripping protocols and appropriate hydrolytic stability will be described.

Jan 1, 2003

By Michael E. Stout

M.A. Industries, Inc. has developed and is now offering on a commercially available basis, complete systems to recover and recycle lead from spent SLI batteries. The system begins with the breaking and separation of the component parts of the batteries and subsequent treatment of the effluent water produced by this operation. The recyclable materials recovered from this process are metallic lead, lead paste and polypropylene. The lead paste is introduced into a process to convert it from a lead sulfate to a lead carbonate. The process also regenerates the salt solutions into reusable carbonate. The lead carbonate is then leached into an acid bath where it is later recovered by a proprietary electrolytic process. The metallic lead is recovered in a short rotary furnace producing metal for further refining and alloying. The polypropylene is further washed and then introduced to a reclaim extruder along with the proper modifiers and additives. The resulting resin can then be sold on the open market to injection molding processors. This complete system greatly reduces the amount of waste to be disposed of and completely complies with all applicable EPA guidelines.

Jan 1, 1993

By Young-Sool Jin, Heung Nam Han, Hong Joon Kim, Jae Kon Lee

A mathematical model was developed considering non-symmetric cooling' and stress distribution in both thickness and width direction of strip on a run-out table of hot strip mill. In order to solve a transient heat transfer equation including the heat evolved from phase transformation, a finite element method coupled with thermodynamic and kinetic analyses was applied. The heat capacity of each phase and heat evolution due to phase transformation were obtained from the thermodynamic analysis of the Fe-C-Mn-Si system based on a sub lattice model. The phase transformation kinetics of the steels was derived by using an inverse additivity technique with continuous cooling experiments. Heat transfer coefficients of strips on the run-out table were, by applying an inverse method, determined from the actual mill data under various cooling conditions. As for the stress analysis, the density change of strip due to cooling and phase transformation, and the transformation superplasticity were considered. A 90nstitutive equation for the transformation superplasticity, which is related to the phase transformation kinetics and the internal stress due to the density change of strip, was applied. A finite element method was adopted to calculate the deformation behaviour of strip on a run-out table of hot strip mill. Using the models, the temperature-phase-deformation history and distribution of a strip on the run-outtable was calculated.

Jan 1, 2001

By Patricia A. Wells

In the remelting of scrap, the ultimate goal is to produce clean aluminum while minimizing metal losses. Recently, it has become more difficult to make significant recovery improvements in Reynolds' Reclamation Plants since metal recoveries were nearing the theoretical maximum. In an effort to gain a better understanding of the factors impacting Reynolds remelting process, a series of experiments using a Taguchi-type design was performed. Specifically, the critical variables and interactions affecting metal recovery of shredded, delacquered Used Beverage Containers (UBC) melted in a side-well reverbatory furnace were examined. This furnace was equipped with plunger-style puddlers and metal circulation. Both delacquecing and melting processes operated continuously with downtime only for necessary mechanical repairs. The experimental design consisted of an orthogonal array with eight trials, each using nominal 500;000 lb shred charge volumes. Final recovery results included molten output and metal easily recovered from dross generated during the test.

Jan 1, 1995

By Leonardo Mota, Lucas L. da Costa, Milton B. Filho, Sergio N. Monteiro, Helion Vargas, Tammy G. R. Portela da Silva

"A natural biofoam extracted from the buriti palm tree has shown characteristics for potential substitution of synthetic foams. In the present work, a photoacoustic thermal characterization was performed on buriti biofoam samples. An open photoacoustic cell technique and a photothermal rise method performed under continuous laser illumination were employed in order to determine the thermal diffusivity and the specific heat capacity of such material. In addition to their intrinsic values (finger print), these physical parameters represent the light-into-heat conversion efficiency and the amount of heat stored per unit volume, respectively. The results showed that the buriti biofoam presents thermal properties that permit its use as an effective insulation material.IntroductionSolid foams are very light materials with increasing engineering applications [1]. A natural biofoam obtained from the petiole of the buriti palm tree (Mauritia flexuosa) has been recently investigated [2-4]. The evaluation of the buriti biofoam properties and the characterization of its microstructural aspects have shown that this biofoam has a potential as a new engineering material with very low density. Additionally, its reduced open porosity and low absorbed humidity revealed a promising material for packing and floating applications. In fact, this buriti biofoam, extracted from the palm tree natural of the north region of Brazil, is being used by the low income population as a modest substitute for Styrofoam® [1].As a potential insulating material, the buriti foam needs to be characterized in terms of its thermal and acoustic properties. A preliminary investigation [3] on the thermal behavior of this natural biofoam by thermogravimetric analysis, TGA, and its derivative, DTG, as well as differential scanning calorimetry, DSC, revealed parametric conditions associated with water loss and structural decomposition. Both the surface humidity and the release of hydration water were determined. Different decomposition events were attributed to both, more rigid as well as to more flexible molecular segments. Table 1 depicts technical data obtained so far for the buriti biofoam. These data are compared to those corresponding to Styrofoam®."

Jan 1, 2011

By E. Fockedey

he destruction of free cyanide on a Co3O4 doped carbon felt was studied. The experiments were done with an eiectrochemical filter press cell on dilute alkaline solutions containing 250 mg/l NaCN. No chloride ions were added to the solutions. The cobalt oxide protects the felt against corrosion and has a catalytic effect on the degradation of the cyanide. This kind of electrode allows working with current density as high as 1200 Aim without any visible degradation of the felt. The most interesting results were obtained with a current density of 400 Aim' at which the cyanide concentration can be lowered to 5 mg/l with a current efficiency of more than 70 % and a specific energy consumption of about 10 kWh/ kg CN.

Jan 1, 1998

By John Wallace

"Monitoring compound semiconductor crystal growth using multifrequency eddy currents for sensing illustrates some of the extreme problems of measurement and interpretation that are not often seen in metallic systems. Using sensor arrays and scanning sensors have produced a qualitative and quantitative understanding of some of the high temperature electrical conductivity mechanisms in several compound systems. A detailed review of the CdTe/CdZnTe data is presented showing some of the complexity in the data as opposed to what is found in elemental semiconductors.HistoryThe most common goal in the use of eddy current measurement in crystal growth is to deter-mine the curvature of the liquid solid interface during growth to test if the heat transfer estimates of the thermal design were adequate for single crystal growth[l]. This aim could be met but represented only a small fraction of the data that was produced observing a growth cycle. A secondary consideration was what could be discovered in the recorded data about the growth and subsequent heat treatment as the boule cooled. This is usually a more difficult task because a crystal growth process is not a controlled experiment so much as a process that continually sees modification. Using a sensor arrays or a scanning loop has produced a qualitative and quantitative basis for understanding some of the high temperature electrical conductivity mechanisms. The implication of the these measurements of electrical conductivity variations are important in that they reflect the complex defect states that will occur on cooling and heat treatment following crystal growth. In contrast to the complex behavior of the conductivity of these compound semiconductors in the solid and liquid state we have the very well characterized system silicon to compare. Initially the interest on using eddy currents to monitor compound semiconductors came from G. Westphal at the Texas; Instruments Company in 1987 to monitor aspects of growth and compounding of GaAs. This was followed by work on solution growth of HgCdTe with D. Witter. The initial interest in the use of eddy cur-rents for monitoring CdTe crystal growth came from Prof. Wilcox at Clarkson University in the practical interest to determine and control the crystal interface curvature during vertical brigdeman growth. The first actual work was done by one of his former students. G. Neuge-bauer at the II-VI Corporation which was carried on by G. Rosen at Clarkson and R. Shetty at II-VI Corporation and with A. Socha at Johnson-Matthey Electronics. The work on CdTe extends over four years and yielded sufficient data to allow one to evaluate the utility of the information produced as compared to what could be obtained from monitoring an elemental semiconductor such as silicon."

Jan 1, 1997

By Animesh Jha

The carbothermic reduction of chalcopyrite has been studied in the temperature range 1073 to 1273K in presence of lime. The role of lime during the reduction process is explained and the phase equilibria leading to the metallisation of copper and iron are discussed. The effect of coal and carbon monoxide on the reduction process have been studied and the rate governing steps are identified. This investigation also cites examples of possible mechanisms of physical separation of metallic Cu from iron during the reduction process.

Jan 1, 1992

By Kazuyoshi Shimakage, Shinji Hirai, Kenji Wada

"An amorphous zirconium oxide coating was prepared by the sol-gel process using zirconium tetra-n-butoxide on the surface of aluminum to improve the corrosion resistance to salt, acid and alkaline attacks. The coating films formed on the smooth aluminum substrates under UV-irradiation indicated an excellent corrosion resistance for salt, acid and alkaline attack tests. For example, the corroded area of coating film in salt attack test for 3600ks in the order of sol-gel coating· film< chromate film <boehmite film, and the sol-gel coating film had the best corrosion resistance. The coating film prepared on the coarse aluminum substrate by a boiling treatment after heat treatment at 573K also had greater corrosion resistance, and a water-avid surface appeared a contact angle of approximately 3°.IntroductionAs given in a previous paper1; a composite film consisting of a porous layer of anodically grown aluminum oxide filled with amorphous zirconium oxide and an amorphous zirconium oxide coating layer deposited thereon via the sol-gel process utilizing the dip-coating technique, was prepared to improve the alkaline corrosion resistance of aluminum. The alkaline corrosion resistance of these composite films was increased in the range of 24 to 50 times those of conventional anodic oxide films anodized in sulfuric acid. As a result, it was proved that heat treatment at 573K after dip-coating was an important process to .remove organic component from gel film and to accelerate the densification of coating layer. Furthermore, the effect of ultraviolet (UV) irradiation at ambient temperature on the densification of coating layer was also examined to lower the heat-treatment temperature2.Then, a sol-gel film prepared by UV irradiation at ambient temperature indicated that alkaline corrosion resistance of aluminum was superior in the range of 2.4 times to 2. 6 times that of the conventional composite film heated at 573K."

Jan 1, 2000

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 B. J. Jody

At Argonne National Laboratory, we have been developing a potentially economical process to recycle automobile shredder residue (ASR). We identified three potentially marketable materials that can be recovered from ASR and developed technologies to recover and upgrade these materials. We built and tested a field-demonstration plant for recycling polyurethane foam and produced about 2,000 lb (907 kg) of recycled foam. Several 300-lb (I36-kg) samples were sent for evaluation and were found to be of marketable quality. We are also preparing for a large-scale test in which about 200 tons (181 tonnes) of ASR-derived fines «0.25 in. [<0.62 cm]) will be used as a raw material in cement making. A major cement company has evaluated small samples of fines prepared in the laboratory and found that they meet its requirements as a substitute for iron ore or mill scale. We also produced about 50 lb (23 kg) of recycled acrylonitrile butadiene styrene (ABS) from obsolete automobiles and found that it has properties that could be readily upgraded to meet the specifications of the automotive industry. In this paper, we briefly discuss the process as a whole and summarize the results obtained from the field work on foam and fines recycling.

Jan 1, 1996

By Masami Taguchi

"It is found that lead monoxide, PbO, has an ionic conductivity, and the all solid-state electrochemical cell using this oxide as an electrolyte has attracted the attention of battery researchers. In this study, thin film PbO2/PbO/Pb solid cells were produced on glass substrates and their discharge properties were investigated. The acti.ve material for the positive electrode, PbO2, was obtained by reactive sputtering of a Pb target in oxygen plasma. The PbO electrolyte and the active material for the negative electrode, Pb, were vacuum evaporated from /3 -PbO powder and a Pb block, respectively. The open-circuit voltage of the cell agreed with the theoretical value based on the thermodynamic data, and the close-circuit voltage was improved by the addition of a univalent impurity such as sodium or potassium to the PbO electrolyte. The connection of the cells in series and in parallel produced a higher electromotive force and a larger capacity. Also, the charge-discharge cycling test revealed that the cell could be charged and function as a storage battery.IntroductionGenerally, the ionic conductivity of a solid-state electrolyte is lower than that of a liquid electrolyte near room temperature. This has been a serious obstacle to using such electrolytes in an electrochemical cell. However, some solid-state electrolytes, which can preferentially pass a specified ion and have high ionic conductivity, have been found. Lead monoxide, PbO, which is an oxygen ion conductor, is such an example (1)(2). If a solid-state electrolyte is adopted for use in an electrochemical cell the problem associated with a liquid electrolyte such as leakage can be alleviated. The cell structure also can be simplified, because the electrolyte plays the role of separator to prevent the active materials from mixing. Thus, physical vapor deposition technology may make it possible to develop a very thin film cell, which consists of only solid phases (3)(4). In this study, the thin film PbO2/PbO/Pb solid cell with a thickness· of only a few micrometers, in which all the constituents were systematically deposited on a glass substrate by reactive sputtering and vacuum evaporation, has been produced and the charge-discharge properties were investigated. An attempt was made to improve the discharge properties by doping impurities such as Na2CO3 and Sb2O3 into the PbO electrolyte. Moreover, the connection of the cells in series and in parallel to get a higher electromotive force and a larger capacity, and the charge-discharge cycling test to determine its use as a storage battery were carried out."

Jan 1, 2000

By B. R. Adams

This paper discusses the use of a reacting CFD model to determine chalcopyrite kinetics in a drop tube furnace and to predict the reaction of a chalcopyrite concentrate in the reaction shaft of an industrial smelter. Reacting CFD codes can be applied to determine the consequences of the interaction of gas with particles and therefore improve the ability to derive kinetic parameters that take into account the temperature and oxidation histories that different particles will see. This paper describes the application of such a model to derive improved kinetic parameters for the pyrolysis and oxidation of chalcopyrite. The reaction shaft model includes the effects of turbulent fluid mechanics, entrained flow mixing, turbulent particle dispersion, heterogeneous particle reactions, radiative and convective heat transfer, and&apos; surface and bath deposition rates. Particle reaction and composition characteristics are predicted as a function of particle trajectory and deposition and are used to aid in evaluating shaft performance.

Jan 1, 1999