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By LuisW. Pommier

The industrial wastes generated by the plating industry, the circuit board manufacturing industries and other related industries normally contain high concentrations of metals, which make them hazardous. The extraction of the contained metals and their separation may be achieved by both pyro and hydro metallurgical processes. Some of the industrial wastes, those rich in some metals like nickel for instance, are being treated like mine ore concentrates and are being fed to smelting furnaces. The slags from these smelter operations are hazardous. They have, however, special environmental dispensations issued by the regulatory authorities. Hydro-metallurflcal processes have been reported. They also generate a residue which is hazardous because not all the valuable metals are leached out and also, because "non valuable" components, like chromium, are less readily leached. Residues from the plating industry, containing nickel, copper. zinc, iron and chromium as the major constituents and also sodium and calcium, together with cadmium, cobalt, lead. manganese, magnesium, molybdenum, and potassium, have been processed for the extraction of the valuable components. The generation of electrolytic nickel, copper and zinc and also of ferric chloride and chromium oxide is reported. The operation is achieved by a caustic leach for the extraction of zinc, followed by a sulfuric acid leach for the extraction of nickel and copper. This acid leach also extracts the iron and some chromium. The nickel copper and zinc are rendered pure by electrolysis, the iron is oxidized for the production of ferric chloride and the chromium is recovered as an oxide. The leaching operation is performed in two stages, first at a pH of 2.5 to generate an electrolyte for the partial recovery of the metals and then at a pH of 0.5 for the complete extraction of the metals. This leaching operation generates a residue, which although small in volume compared to the initial feed, still contains traces of the valuable metals and a portion of the chromium which makes it hazardous. Additional leaching with hydrochloric acid or nitric acid is required for its complete dissolution. The other minor constituents mentioned are present in concentrations each of less than 0.1% and are handled as impurities in the process. The metals which are soluble at a pH 0.5 and precipitate between 0.5 and 2.0 are bled off. Other impurities will concentrate on the raffinate from the solvent extraction operations from whence they are bled off. These bleeding streams are hazardous and the "impurity metals" are now present in concentrations which would make them valuable, however, the size of these streams is so small that they do not warrant their processing, however they could be marketed to specialized smelters. The extraction of the valuable metals, of the hazardous constituents, the generation of a marketable mixture of minor constituents and the production of a non-hazardous residue for declassification is profitably achieved.

Jan 1, 1998

By Michael E. Stout

The recovery of the constituent components of spent lead acid batteries was pioneered in the early 1970's by M.A. Industries, Inc. MA's main reason for research and development in this area was to recover the polypropylene casings for use as feed stock in their injection molding plants. At that time spent and reject casings were either disposed of or being fed with the lead 'bearing materials into the ,smelting process. M.A. has since developed, built and operated plant for the conversion of scrap casing into reusable copolymer resins. The system is composed, of washing, .sizing, extrusion and pelletizing the polymer into a form which is ready to be injection molded into new products.

Jan 1, 1995

By R. G. Hilton

This paper deals with application of Super Detox? stabilization technology to the treatment of electric arc furnace dust (US-EPA listed hazardous waste KO61 ). The process has been used on approximately 170,000 tons of electric arc furnace dust. In addition to the nearly four years of commercial experience at Sterling, Illinois, the process is now being permitted for application at two other locations. The process was originally developed by the Bethlehem Steel Corporation and then further improved by Conversion Systems, Inc. (Bethlehem Steel's Licensee). The treatment process offers many unique bases for its selection, including: A) Low cost compared to the treatment alternatives; B) Lowest available TCLP leachate levels for any process treating K061. Many other processes leave some residue that represents a disposal requirement, although often not addressed; C) Produces minimized final waste disposed, including the fact that the total volume of dust generated and less than the volume occupied by the residue slag from HTMR; and, D) Opportunities for the beneficial utilization of part or all of the waste stream through the development of chemical and physical characteristics. Each of these aspects will be specifically discussed in the paper, including that status of the operations now under permit.

Jan 1, 1994

By O. Nakai

In the copper electrorefining process, the quality of the starting sheet is one of the basic factors for producing high quality copper cathodes. A highly automated and advanced facility for the production of copper starting sheets was constructed at the Toyo Copper Refinery in 1992, bringing various improvements into an automatic stripping system using stainless steel mother blanks. In 1998, the refinery expanded the tankhouse by another 128 commercial cells, and introduced 64 polymer concrete cells in a first stage conversion. As a result, the Toyo Copper Refinery now has the capacity to produce 103,200 t/y of cathode copper. Construction has led to great improvements in the materials handling facilities and computer associated short-circuit detection technology. This report summarizes the improvements made in the quality of the cathodes and in plant productivity.

Jan 1, 1999

By Ting Lei, Mingjun Rao, Guanghui Li, Tao Jiang

"With the rapid development of iron and steel industry, the supply of iron ores can not meet the present demand for iron and steel industry in China. Large reserves of oolitic hematite have been discovered with low iron grade (30% ~ 45%) and high phosphorus content (0.4% ~ 1.8%). Traditional processes for utilization of this ore are characterized as either high cost or low dephosphorization. In this study, sodium salts-modified paigeite (SSMP) was added to enhance on the dephosphorization of high-phosphorus oolitic hematite by using reduction roasting followed by magnetic separation. Various parameters, including the amount of SSMP, reduction time,reduction temperature, grinding fineness and the magnetic field intensity were investigated. As a consequence, a magnetic concentrate of metallic iron powder with total iron grade of 93.2% and phosphorus content of 0.08% was obtained under the optimal conditions. The results also provide a potential avenue for the comprehensive utilization of paigeite ore.IntroductionOolitic hematite is currently recognized as one of the most refractory iron ore resources in the world. Over 4.0 billion tons of reserves of such resources have been found in China, and more than 10 billion tons in the long-term. This kind of ore is characterized as low iron grade (30%~45% TFe) and high phosphorus content (0.4%~1.8% P), as well as fine particle size distribution of ferrous minerals (the size distribution varies from 5~30 µm, even less than 2 µm) and the complex association between iron and other gangue elements [1~5]. The unique structural characteristics of the high phosphorus oolitic hematite make it difficult to obtain high iron recovery and good dephosphorization efficiency by using the conventional processes [1,2]. Traditional processes are characterized as high cost and low dephosphorization for oolitic hematite beneficiation [9~15]."

Jan 1, 2012

By John L. Sundstrom

Complete systems were designed -and are in operation to recycle the effluent streams and to remove impurities from tankhouse. electrolyte, Heavy em¬phasis was placed on making usable products from as many streams as poss¬ible at minimum capital and operating costs. Almost complete recycling: and reuse of water and sulfuric acid were paramount. Techniques used in-clude solvent extraction - electrowinning, evaporation - crystallization and filtration.

Jan 1, 1992

By Alan DonaldsoN

Plasma Quench production of titanium is the thermal dissociation of titanium tetrachloride into gaseous titanium and chlorine followed by rapid quenching to prevent back reactions. Titanium tetrachloride dissociates into titanium and chlorine atoms at 5000 K. Expansion through a Delaval nozzle accelerates the gas to supersonic speed cooling it very rapidly. Cooling rates are as high as 7exp 1 0 Kelvins per second. Injected hydrogen reacts with condensed titanium particles to form titanium hydride and with the chlorine to form hydrogen chloride. We have produced titanium powder at 20 kglh in a continuous reactor. Costs are projected to be lower than the Kroll Process at large enough scale. Most of the cost reduction would result from elimination of magnesium as a reducing agent and much lower capital costs.

Jan 1, 2001

By R. S. Celmer

The distributions of cobalt, molybdenum, copper, and selenium between nickel matte and silica-saturated iron silicate slag have been determined in the region of the metallic saturation boundary, at 1523 K. Results are given as a function of the composition of the coexisting Fe-Ni alloy and the activity of iron in the system. Under strongly reducing conditions, these minor elements display a marked preferential accumulation in the sulphide phase. It is shown that the dissolution of cobalt and molybdenum in slag follows an oxidative mechanism, and distribution equilibria are correlated with the oxygen potential. From these data, the thermodynamic properties of cobalt in nickel matte are computed. Further, comparisons of minor element partitions are made between the nickel and copper matte smelting cases under metal saturation conditions.

Jan 1, 1988

By A. F. Sidorov

A method of improving mineral recoveries from ores by modifying the physical and chemical properties of minerals using radioisotope radiation was tested. It was observed that irradiation modifies mineral cell sizes, changes the crystal structure of some minerals, reduces the sulfur content 1 to 1.5 % in sulfides, changes the zeta potential, alters the surface properties of mineral grains I and produces other changes. Preliminary tests indicate that accelerated electron treatment of ores in connection with mineral processing has a potential for improving mineral recoveries by flotation and by magnetic separations.

Jan 1, 1989

By M. A. Barron, D. Y. Medina, R. T. Hernandez, I. Hilerio

"Chromium Nitride (CrN) thin fihns were deposited on steel AISI 316 substrates with reactive magnetron sputtering method. CrN films were produced under two different conditions. In the first one, the substrate was heated by a d.c. source. At the second coating was applied a negative substrate bias voltage. X ray diffraction, quantitative energy dispersive and scanning electron microscope, were employed to characterize their phases, chemical composition and microstructure. Additionally microhardness was evaluated using a microhardness tester. The results show that the phase formation of CrN thin films in the first case (with temperature) is better. Both coatings presented homogeneous surface. Their compositions shows differences though that gases flow are same. In attention to their hardness, presents an increment if it's compared with hardness substrate.Nomenclature.P Ar =Argon gas pressure during coating.PN2 = Nitrogen gas pressure during coating.Ts = Substrate temperature during coating.T f = Coating melting temperature. (CrN = 1050°C).E=Potential difference.t =Coating time.P=Target power (Cr) in magnetron sputtering de.HV = Vickers hardness.F = Applied charge.d= Average length of longitude of the two diagonals (mm)Introduction.Wear causes losses in materials surface, generating that components of mechanical systems suffer irreversible changes in their properties, causing a faulty operation of the system. It is important to control their effects, measuring and interpreting their causes clearly."

Jan 1, 2013

By O. Chemezov, Yu Zaikov, A. Apisarov, A. Isakov

"Silicon deposits containing 99,9 wt.% of main component were obtained by SiO2 electrolysis from chloride-fluoride melts. The operating temperature was varied from 973 up to 1073 K. The conditions for obtaining crystalline fibrous micro- or nanodeposits were determined. The deposits were investigated by ESM methodIntroductionThere are large reserves of natural quartz of high purity in Russia. Processing of this raw material by electrolysis in molten salts produces silicon containing 99.9 weight percent of basic substance.[1]This method is less energy-consuming in comparison to existing methods for producing high purity silicon from gas phase.Another advantage of the electrolytic method for producing silicon from its oxide in molten salts is the possibility of production of high-purity silicon under air atmosphere. It dramatically reduces costs of the electrolytic cell construction, and the operating costs at electrolysis.On our opinion, the main advantage of the electrolytic production from SiO2 in molten salts is a unique opportunity to obtain micro-and nanostructures of silicon deposits. In particular, it is possible to obtain fibrous structures of silicon. The electrolytic method allows smoothly adjusting the thickness and length of silicon micro- and nano-wires by varying the cathode current density and temperature of the process."

Jan 1, 2012

By I. G. L. Sinclair

The Selbaie deposit is located in northern Quebec. It is comprised of three distinct, but genetically related, Cu-Zn-Ag ore bodies which also contain economically significant amounts of Au. The deposits are Archean in age and volcanogenic in origin. At Selbaie, ore microscopy has been employed to aid in planning of ore beneficiation methods and to monitor the ongoing performance of the concentrator. Examples of both types of study are described. Early in the life of the mine, excessive amounts of Zn appearing were found to be appearing in the Cu concentrate. Microscopic examination of concentrates showed that this was being caused by the presence of coatings of supergene chalcocite on sphalerite grains. Fine coatings of supergene galena and chalcopyrite were also observed on some sphalerite grains. The presence of Ag and Au in the ores makes an important contribution to the revenue of the mine. The various modes of occurrence and mineralogical relationship of these two metals are described and discussed. Monitoring of the ongoing concentrating process at selbaie is done by qua-litative and quantitative examination of products collected at various points along the circuit. Causes of such problems as excessive loss of metals to the tailings or inefficient recovery of individual metals, can often be identified and possible solutions proposed.

Jan 1, 1989

By Dengfu Chen, Yunwei Huang, Mujun Long, Kui Lv, Pei Xu, Lin Bai

The surface temperature of continuous casting slab in the secondary cooling zone is a key parameter of production control. However, the accuracy of radiation temperature measurement of high temperature casting slab is greatly affected by the environmental factors, such as water vapor, spray, water film and other participational medias during continuous casting process. In this paper, the radiation characteristics of water vapor and its influences to radiation temperature measurement of continuous casting slab were investigated. Based on the database HITRAN 2004 and the measuring principle of monochrome thermometer & colorimetric thermometer, the measuring errors under different operating infrared spectral wavelength were compared. Results showed that spectral region with wavelength nearby 1.0μm or 1.6μm would be the optimum for high temperature infrared thermometer used under the conditions with moist steam, water spray and water film at the secondary cooling zone in steel continuous casting.

Jan 1, 2016

By F. Raupp-Pereira, G. G. Cunto, J. A. Junkes, D. Hotza, V. P. Della

"The present work investigated the valorization of wastes as alternative raw materials for ceramic industries. Different industrial wastes based on the SiO2-Al2O3-CaO system and classified as non-hazardous were selected: sludge from varvite cutting process, sludge from gneiss breaks processes, sludge from filtration/clarification of potable water and a clay classified also as waste. All as-received residues were characterized by X-ray fluorescence, differential thermal analysis, thermogravimetry and particle size distribution. The applicability of these materials in ceramic formulations was then evaluated. The formulated mixtures were subjected to forming by pressing and extrusion followed by thermal treatment. After optimization of the processing conditions, the properties of the samples sintered at different temperatures were also evaluated. The waste materials studied proved to be alternative raw materials to natural mineral resources for the ceramic industry.IntroductionOne of the most important problems that have accompanied the humanity in recent decades is the environment’s degradation. In the same context, the natural resources exploration and technological development are phenomena which, if aren’t controlled, can cause ecological disequilibrium with unpredictable consequences [1]. It is in this perspective that recycling of various wastes assumes relevant importance.The recycling, understood here as the waste process reuse, is a common practice in the First World countries, where the raw materials have strategic aspects and the disposal techniques of solid wastes have considerable economic costs. In Brazil, the ecological conscience begins to be aroused due to, in the last ten years, the implementation of stricter laws for environmental control, in general, and licensing of waste generating from industrial activities, in special. The terms “residue” or “waste” are normally used to describe what remains of a production process; when an application for this material is not found. When wastes or residues are susceptible to be incorporated as raw materials or energy sources in a new material production, they can be understood as by-products [2].The valorization of industrial wastes is important, due to the need to pollute less and give an ecologically correct destination for wastes. The waste recycling, independent of its kind, presents several advantages in relation to using primary natural resources, such as reduction in the volume of raw materials extraction, lower energy consumption, lower levels of pollutant emissions and improvement of the health and safety of the population. The most visible advantage of recycling is the preservation of natural resources, extending its life and reducing the destruction of landscape and ecosystems [3]."

Jan 1, 2008

By F. Kongoli

Nonferrous and ferrous smelting industries have recently faced the unavoidable necessity of changing and/or improving the smelting technologies as a result of the use of new raw materials which are becoming available from different geographical areas. These new feed materials usually contain different ore composition and higher level of minor components, which adversely affect the smelting process. Due to the problems encountered in several processes as a result of this feed diversification some work has been undertaken in order to make uniform the feed and avoid later surprises in the smelting process. However this has proven to be very difficult and sometimes almost impossible. In this work a more viable approach is undertaken to deal with this problem. It consists of controlling not the cause of the problem i.e. the feed composition but instead the results of this feed change, i.e. the end-point of smelting technologies. It is shown that this approach, when carried out through advances physicochemical modeling and simulation tools is not only easier and less costly but it also helps the control optimization and automation of the smelting processes. Several examples are given and future work is underlined.

Jan 1, 2003

By D. Valic

In 1997, 9.2 million tonnes of mined, recoverable copper was produced, of which, 1.8 million tonnes or 19.4% was produced by leaching, solvent extraction and electrowinning. The amount of copper produced by this method grew faster than those attained from concentrate smelting, signifying the growing importance of this low-cost production method. Statistical experimental design, unlike traditional approaches, allows for proper distribution of experiments within the boundaries of factors being studied such that the number of experiments required to develop a sound relationship between the factors and a response is minimized. In the past, very little use has been made of statistical experimental design in copper electrowinning studies. Traditional one- variable-at-a-time approaches are widely employed for this purpose. The present study employs a factorial experimental design to relate current efficiency with current density (180 and 300 A/m2), copper concentration (25 and 65 gL), and temperature (40 and 60 °C). Pure synthetic electrolyte with a constant acid concentration of 180 g/L was used throughout the study. The designed study produced a linear relationship where the independent variables of current density, copper concentration, and temperature, and their interactions, were found statistically significant. It was shown that current efficiency could not solely be used as a predictor of copper cathode quality. The quality of the deposit is difficult to be incorporated into a model or relation. It was determined that other measures, such as cathode morphology and crystal structure should be considered. This was done through XRD and SEM analysis.

Jan 1, 1999

By Maurizio Marezio Bertini

Ammonia - ammonium sulfate solutions were sparged in a glass reactor with a SO2/O2 gas mixture (2% SO2 and 98% O2) to leach copper from pure chalcopyrite and chalcopyrite concentrate. The SO2/O2 mixture produces higher and faster extractions than O2 by itself. The effect of temperature, particle size and free ammonia concentration was investigated. The fastest and highest recoveries were obtained at 80 oC from a chalcopyrite concentrate with a d80equal to 13 m, with about 83 gpl free ammonia, an average pH equal to 8.75 and a stirring speed of 500 rpm. The extraction process was controlled by diffusion through a product layer, according to the shrinking core model, with an activation energy of 41 kJ/mole.

Jan 1, 2003

By G. Kugler, M. Tercelj

"The use of the up-to date light alloys and their development are in the sharp ascent especially in transportation industry. In the last years the use of the magnesium alloys for the various purposes was strongly increased. The aim of present research was to study the influence of solidification rate on hot workability and on obtained mechanical properties of AM60 magnesium alloy. The study was also focused on possibility to omit prior homogenisation process which would result in cost reduction. The solidification of gravity cast alloy has been investigated with various methods of the thermal analysis: in situ simple thermal analysis and simultaneous thermal analysis. In order to reveal optimal hot working conditions the deformation behaviour was studied in the temperature range 200-450°C and strain rates between 0.001-lOs-1. Mechanical properties have been studied with tensile and impact toughness testing.IntroductionIn recent years, the increased demand for magnesium alloys has been mainly driven by the need of automotive and transportation industry to reduce the weight, as this is the most important parameter to reduce the energy consumption. Beside their very low weight in comparison to other metals, the magnesium alloys are characterized by good machinability, corrosion resistance and good mechanical properties, and can thus compete with aluminium alloys and for some applications even with steels. Due their decreased workabilty they are typically used as cast alloys, but in recent years also the research of their wrought state has become more extensive [1-7]. Decreased hot workability of magnesium alloys originates from their hexagonal close-packed structure. One of the most popular magnesium alloys with great potential for many applications is AM60 (MgA16Mn), which is predominately used for casting. But its application could be increased if the mechanical properties, could be improved. This can be done by hot working. Namely it is well known that wrought microstructure is characterized by better mechanical properties in comparison to as-cast state. On the other hand due to its low hot workability the homogenization process is required prior hot deformation, which results in increased production costs. Thus the aim of the present research was to study the influence of solidification rate on hot workability of AM60 alloy in order to improve its mechanical properties and to check the possibility of producing near-net-shape casting products omitting homogenisation process by employing small additional deformations after casting. Within the framework of this research the solidification of gravity cast AM60 alloy has been investigated with various methods of the thermal analysis."

Jan 1, 2011

By V. A. Shumsky, I. P. Polyakov, N. M. Ospanov, M. A. Lyamina, N. N. Ushakov

Studies on the kinetics of the competitive processes of PbS volatilization and PbS oxidation, as applied to the heat and mass transfer conditions in the flame of the Kivcet furnace, revealed that the rate-determining factor is the supply of heat. Therefore, low yields of fume in the autogenous flash smelting of lead sulphide feeds are noted despite the high volatility of PbS at 1,300-1,400°C. Dust formation in the autogenous flash smelting of Kivcet-smelters does not exceed 5-7%, of which fumes amount to ~ 80%. Using extra fuel during autogenous smelting involves the mismatch of the sulphide oxidation rate and the release of heat in the flame, and increases the fume yield. This is a major cause of the high dust formation in pilot plant trials. The analysis of dust formation in the Kivcet smelting of oxidized lead feeds in an industrialscale smelter shows an overall increase of dust formation (up to 10% of the feed), with fumes constituting ~ 80% of the dust. A pronounced increase of the zinc component of the fumes is also noted. Lead

Jan 1, 2000

By Veneta Groudeva

A pyritic ore containing zinc, lead and copper as? the relevant primary sulfide minerals, .as well as gold and silver finely disseminated in the sulfide matrix, was? leached in percolation columns. Each column contained 30 kg of ore crushed to minus 10 mm. Firstly, zinc and copper were efficiently leached by means of chemolithothrophic bacteria? in acidic sulfate bearing medium. Zinc was leached more rapidly than copper but the final extractions of these metals were similar (about 75% in 300 days). A part of the galena was oxidized to the. insoluble lead sulfate during the leaching. The pyr:ite was, however, relatively slightly attacked. The ore was then leached by means of FeC11 - HCl solutions both in the presence and in the absence of bacteria to solubilize the lead. The chemolithotrophic bacteria grew in media containing both chloride and sulfat~ ions and maintained a high ferric to ferrous ion ratio in the percoiating solutions. The chemical leaching was, however, more efficient since ft was possible to carry it out at higher chloride ion concentrations. About 10% of the lead was leached in this way in 90 days. Finally, the ore was leached by thiourea in the presence of a gold-oxidant (oxone) to extract the gold and silver. Over 60% of the gold and over 55% of the silver were extracted from the ore in 150 days, while. the extractions of these precious metals from an untreated ore sample were lower than 25%.

Jan 1, 1991