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By W. L. Dalmijn

The processing of scrap and scrap cars starts with size reduction by a hammermill, or shredder. After the liberation the magnetic fraction is removed. The remaining non¬magnetic fraction mixed with other materials is screened and each fraction is processed separately. The increased use of plastic has a negative effect on the recovery of metals and waste production. At Huron Valley, Belleville Michigen, USA, the non-ferrous fraction from 5 million obsolete cars per year, containing 200,000 tons of non-ferrous metal, is processed. Aluminium Is recovered with a heavy medium separation process and concentrated with eddy current separators. The remaining heavy non-ferrous fraction is concentrated by a new combination of eddy current separation and image processing. After this separation process the zinc fraction is melted and refined and the copper, brass, stainless steel and other high-quality concentrates are sold to the secondary industries. The recycling of car scrap has become an important source of metals and materials for the secondary. materials processing industry.

Jan 1, 1995

By James A. Voigt

"The efficient separation of metal species from aqueous streams by precipitation techniques requires a fundamental understanding of the various processes that occur during precipitation. These processes include particle nucleation, particle growth by solute deposition, agglomerate formation, and agglomerate break-up. The application of the population balance approach has been used to develop a kinetic model that accounts for these competing kinetic processes. The usefulness of the model is illustrated through its application to the precipitation of yttrium hydroxynitrate, YHN. The kinetic parameters calculated from the model equations and system specific solution chemistry are used to describe several aspects of the effect of pH on the precipitation of the YHN. Implications with respect to the simultaneous precipitation of more than one cation type are also discussed through use of example systems. The effects of solution chemistry, precipitator design, and solvent choice are considered.IntroductionThe application of precipitation technologies to the separation of metals from solution is widely used. Regardless of its application, be it in such diverse areas as the preparation of metal oxide powders for use in commercial products or as a unit operation in the removal of trace metals during wastewater clean up, the fundamental processes involved are the same. These processes include: nucleation from solution, either homogeneous or heterogeneous; growth from solution with chemical reaction either in solution or at the precipitate/solution interface; growth by particle agglomeration; and particle break-up by collisional or shear forces. The effectiveness of the operation and the properties of the precipitate formed, or ""quality"" of the product, are determined by the competing kinetics of the different processes. The kinetics of the processes, in tum, are determined by system-specific solution chemistries and the conditions used to carry out the precipitation operation. For example, generally, when system conditions are such that the supersaturation driving force for precipitation is very high, growth species normally do not have the time to organize themselves with a high degree of crystallographic order and the precipitate is amorphous. In this case nucleation rates are invariably extremely high and the primary mechanism for growth is the agglomeration of nuclei. Conversely, when the supersaturation levels for the same system are reduced, the kinetics of the nucleation and growth processes also are greatly reduced, and a crystalline precipitate can be formed, since the growth species have time to order on particle surfaces."

Jan 1, 1996

By R. G. Reddy

Industrial copper reverberatory furnace slags were treated by high temperature techniques (sulfide and carbothermic reduction) to recover copper in alloy or matte phase at 1473K. Recovery was investigated for the condi¬tions of varying amounts of metallic sulfide, carbon and CaO additions. The results showed that recovery of copper increased with increasing amounts of carbon addition, and also is strongly dependent on the initial concentration of copper in the slags. Copper recovery for both carbothermic reduction and sulfide treatment were modeled with linear relationships as follows: for carbothermic reduction (%Cu recovery) = 9.0 (%Cu in slag)initial 73.8 and for sulfide (%Cu recovery) = 7.1 (%Cu in slag)initial 82.2 Higher copper recovery was obtained with sulfide treatment than with carbothermic reduction of slags.

Jan 1, 1983

By Mathilde Guilpain

A wide variety of plants are able to extract nickel (Ni) from soils and accumulate this metal in their foliage. Hydrometallurgical processes have been developed to recover Ni in the form of metal or salts, starting from the plant A. murale. They include: (1) a combustion step, to obtain ash containing 15–20% Ni; (2) a leaching step; and (3) purification. That whole flowsheet has been thoroughly investigated, and the processes scaled up to the pilot scale. Another strategy is presented here, consisting of recovering Ni without burning the plant. Ni can be extracted from the dry plant by water leaching, but the leachate is a multi-element solution from which Ni has to be separated. Selective precipitation of Ni hydroxide is not possible since Ni is bound to organic ligands. In this work, the plant leachate is processed by adsorption on the chelating resin DOWEXTM M4195. The results showed that Ni was selectively retained whereas the other main cations were not. Nickel could be recovered at the elution step. This methodology needs to be further investigated but these initial results are very encouraging and open the possibility of Ni recovery by agromining.

By Anette Mueller, Thomas Schnellert, Sérgio C. Angulo

"The use of automatically sorting technique, to separate gypsum components from recycled material of processed construction and demolition waste (C&DW), is motivated by environmental and economical aspects. Only if the gypsum can be separated the aggregates can fulfill the environmental requirements and also the structural characteristics according to the standards. Furthermore, the separation of red brick can also improve the quality of the aggregates.This paper aims at analyzing the separation of gypsum components and red brick by using the color sorting technique. The impacts on the composition and the envelope density of recycled aggregates are described. Depending on the gypsum content the application of two processing stages (rougher-cleaner) can be necessary to produce aggregates with sufficiently low gypsum content. Additionally, the separation of red brick and concrete is successful. So, the color sorting may be a promising technique to upgrade the quality of mixed C&DW aggregates.IntroductionConstruction and demolition waste (C&DW) is a mixture of different materials. Such mixtures can be used only in low grade applications. If the material is used as certified material for road construction or as aggregate in concrete the concrete particles must be separated from the other building materials. This paper aims at analyzing the separation of gypsum components and red brick by optical sorting. The needed stages of sorting for getting a product quality according to the German Standards are deduced.Gypsum is a building material that is increasingly used for interior works in Germany like it is shown in figure 1 [1]. At present the content of gypsum in C&DW is estimated at about 1 %. Assessments on the basis of material streams of gypsum and concrete and their life spans show that higher gypsum contents of about 3 % must be expected in future [2]. Also in other countries the use of gypsum has grown considerably in the last decades. From the characterization of C&DW available in some cities in Brazil, 4 to 15 % of total amount of C&DW that may arrive at the recycling plant to be processed is excessively contaminated by gypsum. In one of these cities, the average content of gypsum in the C&DW before processing was as high as 2.1 % [3]."

Jan 1, 2008

By Xiangwen Wang

Electrodeposition of lead metal from high purity brine electrolytes containing lead chloride (PbCI,) was conducted so as to assess the feasibility of electrowinning lead-metal directly from aqueous chloride electrolytes. Tests were performed at 65 and 80°C (338 and 353°K). Characteristic features of the deposits, on both lead and graphite substrates, were correlated to operating parameters associated with: electrolyte temperature, current density and total lead- concentration. Photomicrographs of these morphological features were obtained by use of Scanning Electron Microscopy (SEM).

Jan 1, 1993

By Deming Wang, R. A. Overfelt

"The oscillating cup viscometer has become a dominant technique to measure the viscosities of high temperature molten metals. Unfortunately, the viscosity estimation model from the observed logarithmic decrement and period of the oscillation is very complicated. There are still large discrepancies of viscosity estimation values between using different measurement facilities and using different viscosity estimation models for a same molten metal. The purpose of the paper is to evaluate the accuracy of an oscillating cup viscometer in Auburn University. Two well known viscosity estimation models, Roscoe's and Torklep's equations, are compared and discussed. The theoretical literature for the fluid flow inside an oscillating cup is reviewed and a more accurate working equation for the Auburn oscillating cup viscometer is developed. Some design parameters of the oscillating cup viscometer, which directly affect the accuracy of viscosity estimation by using the working equation, are discussed. In addition, applications and experimental measuring data are presented in the paper for several different commercial alloys, such as aluminum alloys: A319, A356 and A201, nickel-base super alloys: In713 and In718, and casting irons, C40 Gray Iron and Ductile Iron.1 IntroductionThe oscillating cup viscometer is the most important and has been most frequently used in viscosity measurement for high temperature liquids [1-4]. The principal advantages of this technique over others are its mechanical simplicity and the ability to measure the time period and amplitude decay with great precision. In the viscometer, a high temperature liquid (such as a molten metal) is contained within a crucible suspended by a wire to form a torsional pendulum, which induces torsional oscillation motion. This motion is damped primarily by viscous dissipation within the viscous liquid inside the cup. The viscosity of the liquid can be calculated by an analytical or numerical solution ofthe equations of motion of the oscillating cup system."

Jan 1, 2001

By D. Van Dooren

The final goal of the research project is to develop a 3D FEM model that is able to predict the kinetics and micro-structural evolution during the bainitic transformation. The input parameters consist of thermodynamic and atomic mobility data obtained from the ThermoCalc and mCTRA databases combined with structural mechanics data extracted from the stress-strain curves of the fcc and bee phases. In this paper the general principles of the model are outlined and some interesting preliminary results are shown and commented. The full implementation of the model has presently not been achieved yet. In the model the bainitic transformation is considered as a sequence of martensitic (re)nucleation and growth of a ferritic subunit followed by the carbon rejection into the surrounding austenite. The (re)nucleation of the subunits will be described through a non-classical martensitic nucleation criterion. Once a nucleus has been activated at a specific location in the material, a full-sized subunit is instantaneously formed through a displacive mechanism. The stress state in the system that arises due to the transformation strain can be calculated by a 3D FEM programming code. Immediately after the formation of the subunit, another 3D FEM programming code calculates the carbon diffusion from the supersaturated ferrite into the surrounding austenite. The resulting stress state and carbon profiles will be used to determine where and when a new subunit will nucleate based on a renucleation criterion. Keywords: Bainitic Transformation, Modeling, Eshelby, Carbon Diffusion

Jan 1, 2003

By Irshad A. Rana

In a modern copper smelter, the capital cost of a sulfuric acid plant constitutes the largest single cost item of the total investment. It is thus essential to properly size the acid plant in order to reduce its capital cost and enhance the economic viability of a new smelter project. Whereas the off-gas from a smelting furnace is continuous and generally uniform, the gas flow from the Peirce-Smith converters is intermittent with significant fluctuations. The converters off-gas volume is dependent upon a number of interrelating factors. The most significant factors are the matte feed grade, the system air infiltration, the converter's size and blowing rate, the maximum number of converters simultaneously blowing and the gas cooling system employed. The acid plant size, therefore, is heavily influenced by the converter off-gases. Several of these factors are discussed, and their impact in determining the acid plant size is explored.

Jan 1, 1993

By N. V. Gorelikova

A new type of zirconium mineralization has been recognized in the Devonian volcanic rocks from an orogenic depression in the Central Kazakhstan. The most characteristic features of this deposit are the fine-grained nature of the zirconium mineralization, an unusual texture of the zirconium ores, and a close association of zirconium with phosphorus in the ores. Zircon grains form fine globular aggregates with the features of hexagonal crystal habit. In addition to crystalline zircon, the ores contain metacolloidal zircon, similar to hydrozircon. The morphological and textural features of the zirconium ores suggest that the deposition of ore deposits took place at a low temperature from colloidal solutions. It is believed that this deposit should be considered to be a new type of zirconium mineralization that is related to low-temperature hydrothermal processes.

Jan 1, 1995

By R. H. Hanewald

The INMETCO process has been modified so as to recover nickel. chromium and Iron from a wide variety of metal containing waste-streams. This now includes the recovery of metals from spent acid solutions such as chromic acid etching I1quids. nJcke1 and chromium plating solutions; stainless and superalloy pickling solutions. etc. In addition. hazardous electric furnace stainless steel and. superalloy baghouse bags can be processed so as to recover the valuable metall1cs. A detailed review of the above new recovery techniques w1ll be discussed as well as the current operating methods used at INMETCO.

Jan 1, 1992

By Yoshifumi Abe, Akinori Toraiwa

"Nippon Mining & Metals started a new copper anode slime treatment plant that processes slimes in a chloride media. The basic plan of the process was proposed by Mr. James E. Hoffmann and Nippon Mining & Metals modified and advanced to produce precious metals in acceptable qualities for the company. The process has a wet chlorination stage of decopperized slimes, a solvent extraction and a reduction stages of gold, a silver chloride reduction stage and separative reduction stage of its gold extraction raffinate. The new plant of this process started in 1997 and has been operated in good condition.IntroductionThe old anode slime treatment plant of Nippon Mining & Metals, located in it's Hitachi Refinery, processed anode slimes through a combination of pyrometarllurgical processing and electrorefining. There was a need to plan a future of the plant because the maintenance cost increased year by year and a new selenium registration was going to be applied to the plant. Some plans were discussed and the result was that the process proposed by Mr. Hoffmann was superior among them.Nippon Mining & Metals started 'to examine the process and the experimental result showed that the process had an ability to be its new process but further research should be necessary to produce precious metals in acceptable qualities. The final process flow has some modified and additional stages to be suitable for its requirement. Silver processing stage is quite changed. Gold extraction stage has a new step to polish gold loading DBC. Gold extraction raffinate treatment stage is advanced to be able to recover precious metals, selenium and tellurium, separately. Aeration under atmospheric pressure is employed in decopperizing stage.The basic design of the new plant started in 1995 and finished in 1997. The construction of the new plant began in April 1997 and finished in October. The plant has been operating well after the four months test operation."

Jan 1, 2000

By Kaixi Jiang, Lan Li, Bang Wei, Haibei Wang, Yaping Feng

"China is currently the world's largest copper producer. In the last five years, 950 kt/y of smelting capacity was commissioned. Currently, about 1200 kt/y smelting capacity is under construction and about 2000 kt/y smelting capacity is under feasibility study. Ausmelt/ISA smelting and flash smelting technologies were commonly adopted in China. After the double-flash-smelter was first adopted in 2004, three new double-flash-smelters are scheduled. Recently, two new copper smelting technologies were developed in China. One is an improved bath side-blown smelting process, and another is the SK.S bottom blowing process. Both technologies have been in practice for over three years and have achieved good technical performance. Approximately 500 kt/y new smelting capacity in China and India will adopt these technologies. Both technologies have the advantages of low investment cost, low energy consumption and high flexibility for complex raw materials. This paper reviews ""green"" copper smelting projects in China and introduces the practices of the two new Chinese smelting technologies.IntroductionPresently, China is the largest copper producer in the world. As far as the smelting of copper is concerned, there are many smelting processes applied in industrial production, such as flash smelting, Noranda smelting, Ausmelt smelting, Isa smelting, the Mitsubishi process, Vanukov smelting, silver copper-smelting, SKS smelting, both side-blown smelting, traditional blast furnace smelting, electric furnace smelting, reverberatery smelting and so on . Except the last three traditional processes that are eliminated because of their failure to meet the requirements for environmental protection, all of the other above-mentioned methods are advanced smelting processes adopted nowadays."

Jan 1, 2012

By Markus Aspiala, Fiseha Tesfaye, Pekka Taskinen

In this paper, the standard thermodynamic properties of Ag3Sb and Ag6Sb intermetallic compounds have been studied by the solid state EMF-method, using Ag+ ion conducting β- alumina and AgI. The intermetallic compounds were synthesized from pure substances in evacuated silica ampoules and their formation were confirmed by the SEM-EDS analyses. The EMF measurements were made on electrochemical cells of the type [Ag | β-alumina | Ag-Sb] and [Ag | AgI | Ag-Sb]. The usage of β-alumina electrolyte, in this study, enabled thermodynamic measurements of the Ag-Sb-intermetallic compounds above 710 K, hitherto unreported. Based on the new experimental data, thermodynamic properties of the Ag-Sb-intermetallic compounds have been determined. The obtained experimental values have been compared with the available literature data.

Jan 1, 2015

By S. Niyomwas, R. G. Reddy

"A mathematical model was developed to describe the plasma gas and particle dynamics and conversion yields. The velocity and temperature fields in the plasma were calculated by solving 1 the Navier-Stokes equations and the thermal energy balance equations. Conservation equations for the system species consider the multi-component diffusion and chemical reactions. Through the application of this model, temperature distribution, flow fields, and production rates were computed. The model was used to study the thermal decomposition of ilmenite in the non-transferred arc plasma reactor. The computed production rates of TiN from ilmenite using nitrogen and methane gas mixtures, are in the range of 5 to 100 x 104 kg/m3/s at 2500 KIntroductionThe widespread interest in thermal plasma processing has stimulated a great deal of research effort into the various aspects of this process, including plasma' spraying, thermal plasma chemical vapor deposition, plasma synthesis of fine powders, thermal plasma decomposition, plasma melting, and plasma extractive metallurgy.In the plasma synthesis of fine powders, the earlier experimental and theoretical studies aimed at predicting the final products1-5. Then it was followed by more recent investigation concerning the profile of plasma gas velocity, plasma temperature and concentration. In this regard, useful plasma processing models have been reported by numerous investigation6 -11 which were increased by both theoretical analysis and measurement.As a result of this work a reasonable plasma-processing model is proposed. It is to be noted that all the thermal analysis that has been made neglected the fluid -flow effects. Also, in the analysis aimed at the quantitative description of the fluid-flow field, the effect of heat transfer was not taken into account."

Jan 1, 2000

By Kenneth L. Nash

The control of solubility of waste actinide ions, by conversion to highly insoluble mineral phases has been demonstrated in the laboratory. Actinide metal ions are removed from neutral pH solutions by a combined ion exchange-decomposition-mineralization process based on the application of the naturally-occurring hydrolytically unstable.polyphosphate organic compound phytic acid.

Jan 1, 1999

By T. Shibasaki

Purification of copper electrolyte at Naoshima is carried out by two stage liberation to completely depress copper and impurity ions followed by concentration of the solution to produce crude nikel sulfate as by-product. A new nickel recovering process has been developed and pilot tested recently. It consists of the following process steps.; neutralization of spent electrolyte from liberation section to remove free acid and most part of remaining impurity ions, refining and nickel concentration by solvent extraction, and crystallization of pure nickel sulfate from concentrated strip solution. This paper describes the results of laboratory and pilot plant tests, then briefly discusses feasibility of the proposed process.

Jan 1, 1987

By S. E. James

EAF dust has been listed as a "hazardous waste" due to the presence of lead and cadmium, and at times chromium. The 550,00 tpy production of . .EA]' dust, estimated for the United States alone, contains more than 10,000 tpy of lead and about 250 tpy of cadmium in addition to nearly 1'00,000 tpy zinc. Even though the listing of .EAF dust as a hazardous material stimulated extractive metallurgical work worldwide, process development efforts have focused only on the recycle of the potentially-valuable zinc units. However, the recycle of the lead and cadmium, while not lucrative, is the more critical effort. Horsehead Resource Development Company, Inc. (HRD), in conjunction with its sister company, Zinc Corporation of America (ZCA), has taken a unique approach to total recycle of the toxic heavy metals found in the EAF dust. Impure oxide, produced by either a Waelz kiln or FLAME REACTOR Process and containing the lead and cadmium, is calcined in a rotary kiln at Palmerton, Pennsylvania, to produce a refined zinc-rich intermediate for ZCA's electrothermic zinc plant at Monaca, Pennsylvania. During the calcining operation, lead and cadmium are concentrated in a fume product and shipped to ZCA's electrolytic plant at Bartlesville, Oklahoma. At Bartlesville, a new hydrometallurgical circuit has been constructed and the existing cadmium plant expanded. The combined facilities permit the total recovery of cadmium to refined metal and the lead to .a silver-rich intermediate, which is sold to lead smelters. In this paper the Waelzing, calcining and new leaching facilities will be described.

Jan 1, 1990

By Larry M. Southwick

There is much ongoing work in research and development of new processes for the recovery and recycling of met.a.ls and other materials from various waste and scrap streams. Commercialization of such new technologies requires the bringing together and successful execution of a considerable effort involving a variety of activities. These include process conceptualization, research and development, detailed design and construction, and then plant startup and operation. Processes evolve through all of these steps by engineering due diligence, making objective and critical analyses of results, and troubleshooting processing steps to, hopefully, arrive at a sequence that has the best chance to succeed operationally and economically. After a summary review of the above steps, several processes will be described in more detail that provide mostly successful examples of the above procedures. Finally, some observations will be made on areas that will become critical in the near future to the success of new processes for wastes and residues.

Jan 1, 2000

By I. Hilerio

Chromium Nitride (CrN) thin films were deposited on AISI steel 316 substrates by means of the reactive magnetron sputtering method. CrN films were produced under two different conditions. In the first one, the substrate was heated by a DC source. For the second coating a negative substrate bias voltage was applied. X ray diffraction, quantitative energy dispersion and scanning electron microscope were employed to characterize the two different phases, their chemical composition as well as their microstructure. In addition, a microhardness test was carried out. The results show that a better phase formation of CrN thin films was achieved when a heating source was present (first case). Both coatings presented homogeneous surface. Their compositions show differences even when the gases flowing are the same in composition. Regarding to the hardness test results, there can be found a higher value when using a heating source.

Jan 1, 2009