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By Dr. -Ing. Wolfgang Pietsch

Many primary metallurgical wastes are in the sh.-ape of turnings; borings, chips, dusts, and other particuletes. While such. materials can be easily segregated and/or upgraded to yield high quality ?secondary metals with often known composition for easy recirculation into the production? process; their particulate nature results in various problems. Roller presses are used in an ever increasing number for size enlargement and densification of primary particulate metallurgical wastes for secondary metal recycling. The paper will mention the areas of application from A(luminum) to Z(ink), also including Brass; Cast Iron, lead, and Stainless Steel, as well as dusts from all types of melting and ladle furnaces or converters. Typical systems using roller presses for size enlargement. will be discussed.

Jan 1, 1995

By Chengyi Ding, Xuewei Lv, Senwei Xuan, Chenguang Bai, Kai Tang, Gang Li

Sinter is an important iron-bearing material charged into blast furnace. Calcium ferrite (CF) is one of the most significant liquid phases in fluxed sinter. The isothermal reduction kinetics of CF and CF8M (n(CaO):n(Fe2O3) = 1, wt%(MgO) = 8) with 30% CO and 70% N2 gas mixtures at 1123, 1173, and 1223 K were investigated through thermogravimetric analysis in this study. Rate analysis illuminates that the reduction processes of CF and CF8M are mainly expressed as a typical two-stage reaction. Sharp analysis indicates that CF and CF8M reduction is expressed by the Avrami–Erofeev equation presenting a 2D shrinking layer reaction. The apparent activation energy values of CF and CF8M reduction are 46.9 and 31.8 kJ mol−1 individually based on model-free method.

Mar 1, 2018

By M. L. Apel

A conceptual approach to the bioremediation of uranium mill tailings (UMT) is presented., This approach focuses on, biosorption to remediate the. effluent solution and bioleaching remediate the. solid fraction. Comparative biosorption studies were performed with synthetic single metal solutions using a commercially available biopolymer. The maximum rate of metal sorption by calcium alginate was found to be 5.43, 6,39, 6.48, and 9.74 mg dm-3 min-1 for U022*, Ba2+, Cd2+ and Zn2+, respectively. Activation energy (AEa) for barium uptake by calcium alginate beads was determined to be 11.5 kJ, indicating a diffusion controlled reaction mechanism. Thermodynamic values (AG+ AH+ and ASt) of the metal-alginate activated complex, as reported in the literature, were found to be in agreement with those calculated from this research. Results show that this biopolymer can be effectively applied in the removal of select metals prevalent in uranium mill tailing effluents and associated waste streams.

Jan 1, 1991

By Minna Rämä

Iron containing leach residues like jarosite and goethite from electrolytic zinc production contain many valuable metals and harmful substances. These metals and substances should be removed in order to obtain an acceptable, stable and reusable product, and maximize economic feasibility as well as minimize environmental footprint. In this work, the processing of jarosite leach residue was studied in laboratory scale experiments under oxidizing and reducing conditions at high temperatures. First, the pretreated material was melted and oxidized to produce a melt of metal oxides. Second, the oxide melt was reduced in CO–CO2 atmosphere. Target after the reduction step was to obtain a clean slag and a liquid metal or speiss phase that collects the valuable metals, such as silver. The kinetics of the thermal processing were studied for determining optimal times and conditions for the aforementioned process steps. The preliminary results show that the process is thermodynamically feasible, and the desired phases can be obtained in the experimental conditions investigated.

By Christine Wenzl, Christoph Wagner, Christoph Sagadin, Stefan Luidold

Corrosion mechanisms have been investigated between MgO refractory substrates and synthetic FeNi slags. The materials taken into consideration comprised a simple synthetically mixed slag with specific oxides of slags from a ferroalloy producer. The MgO refractory substrates with the slag specimens on it were heated in a hot stage microscope to two different characteristic temperatures, 1350 and 1650 °C. The experiments proceeded under a controlled gas atmosphere that simulates the relevant process conditions. The corrosion mechanisms of each system were determined by SEM analyses. The obtained results showed that slag corrosion is dominating with a pronounced partial dissolution of refractory. It was also observed that iron oxide present in the slag diffused into the coarse refractory grains forming the relative low melting magnesia wuestite. Finally,the comparison of these findings with those predicted by thermodynamic calculation (FactSage) indicated the corrosion mechanisms and draw implications for improving the refractory performance and lifetime.

Mar 1, 2017

By Pengfu Tan

NiModel, a thermodynamic model, database and computer program, has been developed to predict the distribution behavior of Ni, Cu, Co, Fe, S, O, As, Sb and Bi, and heat balance in the nickel pyrometallurgical processes such as Outokumpu flash smelting, Outokumpu direct high-grade matte smelting, INCO flash smelting, and Peirce-Smith converting processes. In this model, as much as 16 elements (Ni, Cu, Co, Fe, As, Sb, Bi, S, O, Al, Ca, Mg, Si, N, C and H) are considered. The compositions of matte, slag and gaseous phases, and heat balance are calculated using the thermodynamic data and the activity coefficients of the components derived from the experimental data. The model predictions were compared with the known industrial data from Kalgoorlie Nickel Smelter in Australia, Outokumpu Harjavalta Nickel Smelter in Finland and INCO Metals Company in Canada, and an excellent agreement was obtained. In this paper, the applications of NiModel in the nickel pyrometallurgical industries have been presented. NiModel has been used by Jinchuan Group Limited in China.

Jan 1, 2004

By Duclerc Fernandes Parra, Vijaya Kumar Rangari, Washington Luiz Oliani, Danilo Marin Fermino, Ademar Benevolo Lugao, Nilton Lincopan, Luiz Gustavo Hiroki Komatsu

Polyethylene is widely used for packing applications. Different grades of polyethylene, LLDPE and LDPE play a major role in the film blowing industry. The use of nanoclay in polymer matrices (non-polar) requires the use of a compatibilizer agent, ethylene graft maleic anhydride copolymer (PE-g-MA), which acts as a bridge for nanoclay-matrix-interaction. In our study, blown films of LLDPE, LDPE, and their blends were produced using a twin screw extruder. The combination of PEs as matrix, montmorillonite (MMT) and silver nanoparticles (AgNPs) intended to improve mechanical and thermal properties. Nanocomposites films with 1 wt% of montmorillonite and 0.5–1.0 wt% silver nanoparticles were prepared by blow extrusion and evaluated. Nanoclay intercalation/exfoliation degree was investigated by X-ray diffraction spectroscopy (XRD) and scanning electron microscopy (SEM). Mechanical and thermal properties were evaluated. The results showed optimum dispersion at intercalation/exfoliation levels for polyethylene nanocomposite (PENC), slight increasing in mechanical and especially improvement in thermal properties.

Mar 1, 2017

By Mark Jolly, Xiaojun Dai

"Foundry engineers in the traditional foundry usually regard the quality of casting component as the most important issue and leave the energy saving or energy efficiency as the subsidiary one. This frequently causes disproportionate energy consumption as a result of the inefficient casting processes used and increases the production costs. This paper presents the novel CRIMSON aluminium casting process and compares its facility and melting process with traditional melt furnaces and aluminium alloy melting process. A real example is investigated to demonstrate quantitatively how the traditional foundry wastes energy and what the improvement of energy efficiency can be achieved using the new CRIMSON method. The results of this investigation will help the foundry engineer recognize the importance of energy saving and demonstrate how to use this new technology to reduce production costs and carbon footprint without decreasing the quality of the cast component.IntroductionAluminium melting in metal casting industry is an energy intensive process where it is estimated that the energy consumption is in the order of 1,700 ~ 4,700 kWh tonne-1 in using crucible and natural gas [1]. Different countries may use different energy resources for aluminium melting: in US the main energy resources are natural gas, electricity and coke [2] and in UK most of the foundry use electricity, gas and oil as energy resources [3]. Due to the pressure of rising energy price and the strict environment law, it is anticipated that under the right socioeconomic conditions, the efficiency optimisation of industrial process can be an important step toward increased industrial sustainability [4]. In metal casting industry the energy efficiency of a casting facility depends largely on the efficiency of its melting and heat treating performance. In association with the two performances, over 60 % of the total process energy costs are represented in a typical casting facility [5] where there are huge opportunities for metal casting industry to adopt the best energy practices for potential energy saving. How to ameliorate the current processes for increasing energy efficiency will have a vital effect on reducing the production costs and increasing the competitiveness. For instance, by implementing some state of the art technologies such as the CRIMSON method in aluminium alloy casting will make use of such opportunities."

Jan 1, 2011

By David Hughes

The paper covers the utilization of on-line analysis in process control of solvent extraction in nickel leach solvent extraction processes in Finland and Australia and in copper heap-leach and solvent extraction in Chile. The goals of and requirements for controlling the solvent extraction stages of the processes are reviewed. The applications at three plants are compared. The development of the technology used is reviewed and design considerations are discussed. Requirements for on-line control and analyzer performance are compared. A new generation of analyzers and its effect on the set-up process of a project is introduced.

Jan 1, 2003

By Guan-Yong SHI, Cong Wang, Zhi-he DOU, Ting-an ZHANG, Shi-gang FAN

Based on the pre-works, this paper proposed a new short stage process of the intensify aluminothermy reduction by the stage to prepare high titanium ferroalloy with low O and Al contents. We investigated the effects of Al and Ca and Si combination reduction agent, slag type and step-up reduction conditions on the Al content and distribution in the alloy. The results show that the step-up reduction can not only reduce effectively the oxygen content in the alloy, but also reduce effectively Al content. For instance, the oxygen content in high titanium ferroalloy is within 1%~4%, and the Al content is within 1%~5%. Its quality reaches the requirement of high titanium ferroalloy prepared by remelting process.

Jan 1, 2015

By Neng-Wen Yu, Miao Wang, Ji-He Wei

The mass transfer characteristic between powder particles and liquid steel in the RH-PTB (Powder Top Blowing) refining has been investigated in a water model of 1/5 scale for a 90t RH degasser. The sodium chloride powder with analytical purity has been used as the flux for blowing. The mass transfer coefficient of the liquid side has been determined under the conditions of RH-PTB process. The influences of the main technological and structural parameters on the mass transfer rate have been examined. The results indicated that under the conditions of the present work, the mass transfer coefficient on the liquid side increases with raising the lifting gas blowing rate, inner diameter of the up-snorkel, circulation rate of the liquid and particle size of powder flux. And it decreases with an increase in the inner diameter of the down-snorkel. It is in the range of (l.36-7.30) x 10·4 mis, the appropriate dimensionless relationships have been obtained as follows:

Jan 1, 2000

By Egil Aukrust

"An American Iron and Steel Institute Task Force evaluated developing direct steelmaking technology worldwide to seek a replacement for the coke-oven, blast-furnace, basic-oxygen process technology now in use. To remain internationally competitive it is essential to move away from the traditional series of batch processes towards continuous processing and the associated energy savings which are possible with high technology process control systems. The group identified in-bath smelting of iron ore pellets or fines with coal as the process most sui table for domestic raw materials (including abundant scrap) and called for research to study operation with varying degrees of preheat and prereduction of the ore by the gases generated from the coal and various degrees of combustion of these gases above the melt.A coordinated, 3-year, $27 million, direct steelmaking research program is proposed. Concurrent projects include design, construction, and experimental operation of an in-bath smelting pilot plant; modeling, simulations, and laboratory-scale experiments at universities on slag-phase and metallicphase reactions and interactions; and large-scale heat transfer and reaction rate trials. Also included are modeling studies and pilot plant trials of on-stream decarbonization and desulfurization; application of circulating fluid bed technology to fine ore reduction and hot gas cleanup; and specific heat transfer and fluid flow research projects.IntroductionThe American Iron and Steel Institute (AISI), based on the Task Force studying direct steelmaking, believes strongly that a coordinated program of research on the reduction of domestic raw materials to liquid steel should be undertaken as part of the Steel Initiative program. To specify the steelmaking process for development best suited to the American steel industry and domestic raw materials, it was important to determine the state-of-the-art of direct steelmaking worldwide, both as practiced and under development, and then, by expert analysis of the processes and their potentials, to choose the process most likely to provide a domestic competitive edge."

Jan 1, 1988

By Flávia Paulucci Cianga Silvas, Otávio da Fonseca Martins Gomes, Viviane Tavares de Moraes, Denise Crocce Romano Espinosa, Jorge Alberto Soares Tenorio, Guilherme Apostólico Bortolini, Stoyan Gaydardzhiev

"Printed circuit boards (PCB) are particularly problematic to recycle because of the heterogeneous mix of organic materials, metals, and glass fiber. PCBs are found in almost every electroelectronic equipment and their recycling process involves a pre-treatment to separate the products which contain targeted metals. In this work, a physical processing involving sequential shredding and hanuner milling were used to obtain a comminuted sample from scrap printers PCBs. The thus prepared sample was analyzed for particle size distribution and by optical microscopy as well was subjected to pyrolysis, leachabilty and chemical composition determination by XRF. The metals concentration was determined by ICP and AAS. The PCBs have been also analyzed by SEM-EDS (micro-analysis and X-ray mapping). The results show that the studied PCBs are lead free, multilayer with 4 copper layers, have 45% of metals and the copper is present in significantly higher concentration than the rest of the metals.IntroductionThe global generation of e-waste (electrical and electronic equipment waste - WEEEs) grows at a rate of about 40 millions of tons per year [ l].Among this e-waste there are PCBs that are present in almost all electronic equipment. Their composition is heterogeneous and varies according to several factors, including: kind of EEE, when and where it was produced, fabrication technology [2], etc. In printers, the PCBs represent about 6.6- 8 wt.% [3].The PCBs treatment may include physical, pyrometallurgical, hydrometallurgical, ectrometallurgical and more recently bio-hydrometallurgical process. Normally there is a combination between these processes [2, 4, 5, 6, 7, 8, 9, 10].The diversity between the different PCBs composition complicates the recycling process since the composition of metal and others materials can vary according to the models. So characterization is an indispensable step before any processing of PCB to begin. Owing to the above said, the main goal of this work has been set to characterize representative samples of PCBs from printers through physical, chemical and microstructural analyses."

Jan 1, 2014

By B. Mishra

Several reactive metal purification processes using molten salts generate effluent from which significant quantities of metal can be recovered prior to discardinglrecycling the salt. A Salt-scrub [SS] process has been applied where the reactive metals are recovered as a metal-gallium alloy by calciothermic reduction of the metal compounds. The SS alloy compositions were produced by mixing, pressing and sintering the metal-powders. Measurement of metal recovery has been studied for cerium, silver, tin and lead. The process has been optimized for variables such as the metal quantity per kg of effluent salt, amount of excess calcium over stoichiometry, stirring rate and time and holding time at reduction temperature. Over ninety-seven percent metal recovery has been obtained under optimized conditions. The development of an alloy for efficient Salt Scrub processing reduces a major contaminated waste disposal problem as well as recovering the valuable reactive metal. Surrogate metals have been used in this work to study the behavior of plutonium.

Jan 1, 1994

By Zhao Hengxian

We studied the phase diagram of Na3AlFe-ZrO system, reduction of ZrO2 by aluminium and electrochemical behaviours of ZrO2 in the system. The results show that Na3ALF6-ZrO2 system is a simle eutectic one, that the velocity of reduction of ZrO2 in the system is rapid al 960'C and that the Zr content in the alloy abtained can reach as high as 2.5wt%. Potential scanning shows that there exist new current peaks on the potential scanning plats except for the cuurent peaks corresponding to the oxidation of aluminium. The method of making Al-Zr alloy in our paper has advantages over the traditional method of mixing metals.

Jan 1, 1992

By Michael A. Krstich

A soil washing pilot plant to treat soils at the U.S. Department of Energy (DOE) owned Fernald Environmental Management Project (FEMP), was designed based on extensive bench-scale testing. The system's design incorporated a combination of physical separation and' chemical extraction processes and was tested on two soils. The textural composition of the two soils was approximately 20 percent sand, 60 percent silt, and 20 percent clay. Since this grain size distribution was not considered optimum for physical separation techniques, thesoil washing pilot plant had to be designed with selected equipment to provide specific soil size fractions during processing operations. A trommel, vibrating screen deck, centrifuge, and attrition scrubber were used in the system to selectively separate specific soil size fractions at 4.75, 2, 0.3, and 0.02 millimeters (mm). The trammel used high pressure water [1000 pounds per square inch (psi)] during the initial step of the process to reduce soil aggregates to single grain composition, separate out greater than 4.75 mm gravel, and dislodge chemical contaminants from the individual soil particles. The vibrating double-screen deck provided 2 - 4.75 and 0.3 - 2 mm soil fractions that, when combined, averaged greater than 75 percent solids for both soils. The centrifuge was designed to take the less than 0.3 mm soil slurry from the screen deck and produce a particle size of 0.02 mm. The centrifuge produced a high solids stream that averaged greater than 70 percent solids for both soils. These 0.02 to 0.3 mm soil solids from the centrifuge were combined with the 0.3 to 4.75 mm soil solids from the screen deck and processed through the attrition scrubber. The data collected from the pilot-plant operation was used to aid in the design of a full-scale system and was instrumental in formulating full-scale process operations and the selection of equipment.

Jan 1, 1995

By Zhang Chuanfu, Tan Pengfu

"A thermodynamic model is developed to simulate nickel flash smelting process. In the nickel flash furnace, oxidation of concentrate occurs at one end, and reduction of slag occurs at the other. The model makes use two zones, namely the reaction shaft/settler zone and the appendage zone and accounts for 6 phases (matte, slag, silica, magnetite, Cu-Ni alloy and gaseous phase), 13 elements (Ni, Co, Cu, Fe, S, 0, N, C, H, Si, Al, Mg and Ca) and 33 chemical components in nickel flash smelting system. The compositions of matte, slag and gaseous phases in equilibrium are calculated by using the data of free energies of formation and activity coefficients of components. Two nickel sulfide species are used to allow for the modeling of sulfur-deficient mattes. The model predictions are compared with the known industrail data from Kalgoorlie Nickel Smelter, and excellent agreement is obtained. The model can be a very useful tool for monitoring and optimizing the actual industrial operations of nickel smelting process. The distribution behaviors of Ni, Co, Cu, Fe, S and 0 in the nickel smelting furnace depend on the process parameters such as smelting temperature, volumes of air, the content of the elements~ charge and oil.1. IntroductionThe nickel flash smelting furnace essentially consists of a reaction shaft where nickel sulfide concentrate is partially oxidized with air, a settle zone where matte and slag are allowed to separate, and a slag cleaning end where coke is added to provide for the reduction of the oxidized nickel from slag, and electrodes are used to provide heat.The theoretical model to consider a mass balance for copper flash furnace is developed by S. Goto and R. Shimpo[1][2J. However, this can not be true for nickel flash furnace as a whole since oxidation of concentrate occurs at one end (in the reaction shaft/settler), and reduction of slag occurs at the other (in the appendage). Despite these limitations, an acceptable pseudo-thermodynamic description of the furnace can be achieved using essentially two zones, namely the reaction shaft/settler zone and the appendage zone. Compositions of gas, slag and matte in two zones are calculated."

Jan 1, 1998

By K. Yamada, T. Takaoka, A. Ozeki, M. Yamaga, Y. Kawai, S. Nishioka, Y. Kikuchi

"Recently, smelting reduction of chromium ore in BOF has been actively investigated as a key unit process for an innovative future stainless steelmaking. The prominent feature of this new process route is energy and process saving, and production cost saving. The development is already in the midst of application to the commercial production, however there still remain the following key technologies to be established for the full use of the process. One is a speed up of the reduction of chromium ore to match with sequential continuous casting, and the other is efficient combustion of carbonaceous materials in BOF to reduce their consumption, and hence to assure the steel quality. High degree of post combustion technology and new charging technology, i.e., ore-coal-flux-oxygen mixed injection, could be effective for those two subjects. In 2000 or beyond, the new process would have become quite popular owing to the establishment of those key technologies.Introduction Since stainless steel was invented, its production has continued to expand because of its attractive combinations of functions of excellent corrosion resistance, good formability, a pleasing appearance, and a wide range of strength levels. New types of stainless steels as well as new applications are continually being developed.Compared to the production of ordinary steels (1), stainless steel production (2,3) shows steady growth worldwide, while the former production remains on the same level, as Figure 1 shows. It can be estimated that future production would show further growth since materials consumer demands are more fashionable, or more functional, which could be satisfied by stainless steels.Thus market needs would be met, if it could be produced with reasonable production cost. The emergence of an innovative production technology is then potentially requested as VOD and AOD processes have emerged, which has saved substantial production cost. This paper describes a possibility of a future stainless steelmaking process, which uses the in-bath smelting reduction of chromium ore in BOF, and which would save production as well as energy cost."

Jan 1, 1988

By Yufeng Guo, Tao Jiang, Jianjun Fan, Haizheng Hao

"Function of High Pressure Roll Grinding (HPRG) in production of oxidized pellets from magnetite concentrate as raw material was systematically studied. It was found that bentonite dosage decreased from 1.3% to 0.8% if specific surface area of magnetite concentrate pretreated by HPRG was up to 2553.41cm2.g-1. The green ball quality improved obviously due to the increase of specific surface area and fine particles content, and the improvements of size distribution and the ballability of pretreated materials. However, the decrease of pellet porosity accelerated the primary solid phase reaction and oxidation reaction, which made the pellets surface form compacted layer that handicapped the diffusion and migration of oxygen, promoting the formation of double layer structure of finished pellet. Consequently, the compression strength of preheated and roasted pellets was not markedly improved by HPRG.IntroductionWith the increase of proportion of pellets in the BF recently, the technical-economic index of BF has obviously been improved. Consequently, the production and the quality of BF pellet are given more attention [1]. However, with the decrease of the quality of iron ore concentrate, the problems such as poor ballability, high bentonite dosage, high preheating and roasting temperature are becoming the great challenges to not only the quality of finished pellets, but also the energy consumption [2, 3]. In order to overcome these problems, mechanical pretreating technologies such as the High Pressure Roll Grinding (HPRG) and Damp-grinding are widely applied. HPRG has a number of advantages such as low energy consumption, high productivity and easy-maintaining. It is more economic and environmentally friendly than the Damp-grinding technology [4, 5]. A great number of experiments have revealed that HPRG can improve the quality of hematite pellets. Although there are some studies of function of HPRG in the magnetite oxidized pellet production, they are not comprehensive and systematic, especially to the preheating and roasting system [1, 2, 6, 7]. Accordingly, the influence of HPRG on the pelletizing system and the preheating and roasting system are systematically studied in production of magnetite oxidized pellets in this article."

Jan 1, 2011

By M. B. Sizgoric

Quantitative mineralogy is used in a study done on an Inco Metals Company nickel sulfide occurrence from 'the Thompson area in Northern Manitoba. The study included: a) determination of the variations in chemical composition of the ore minerals; b) determination of the liberation of the ore minerals for the various types of ore and for different feed grinds; c) assessment of the preliminary mill test results by comparing the mineral distribution in the different tailings. Preliminary mill test results had outlined three main problem areas: 1) unacceptabiy low grade concentrate with, 2) very high weight recovery and, 3) low pyrrhotite rejection resulting in a high sulfur concentrate. The mineralogical study readily explained these results by showing that: 1) between 20 and 40% of the nickel in the feeds and 55 and 75% of the nickel lost in the tailings is associated with pyrrhotite. This accounts in part for the low grade of the concentrates obtained at high recoveries: 2) hexagonal nonmagnetic pyrrhotite constitutes over 90 percent of pyrrhotite. Since hexagonal pyrrhotite floats more readily than monoclinic pyrrhotite, this could be part of the reason for the undesirable high pyrrhotite recoveries into the concentrates. Further test work to establish both the optimal grind and the best conditions for pyrrhotite rejection is therefore mandatory.

Jan 1, 1981