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By Pinakin Chaubal

An analysis of the blast furnace and the low-pressure shaft DR furnace is carried out by redefining the reaction zones. The concept of a characteristic reaction gas temperature (CRGT) is introduced and the two reactors are compared and contrasted using some recent process developments with an aim to develop a platform for further synergistic innovations.

Jan 1, 2006

By M. -V. Wang

Hydrotreating and hydrorefining (HT and HDS) spent catalysts contain molybdenum, vanadium, nickel or cobalt at concentration levels that can make metals recovery economically viable. Quanzhou Jing-Tai of China has developed, through many years of operating experience in metal recovery from spent catalysts, a simple process for recovery of these metals and the production of environmentally benign residues. The process first subjects the catalysts to a low-temperature calcination step, followed by grinding of the calcine. The ground material is then leached with 10-20% v/v hydrogen peroxide to recover metals such as Mo, V and Ni or Co. This step has a selectivity that is greater than 95% for the metals. The undissovled residue, which contains mainly Ah03 and Si02, can be dewaterd and used in the production of masonry bricks. The pH of the rich liquor is then adjusted to between 0.5 and 2.5 by adding dilute sulfuric acid to co-precipitate Mo and V, with a recovery rate of greater than 99%. The lean liquor contains mostly dissolved Ni or Co, which can be recovered through precipitation at a pH of between 8.5 and 9.5 by caustic additions. The final liquor is then sent to an ion exchange step for final recovery and cleanup of residual metals. The effluent is then discharged after a simple wastewater treatment process, which has been found to meet all environmental requirements. The entire process has been found to be simple, cost-effective with minimal environmental impacts while achieving the goal of complete resource recovery from spent catalysts commercially.

Jan 1, 2000

By Ibrahim Yusufoglu, Ahmet Orkun Kalpakli, Cem Kahruman, Sedat Ilhan

"The effects of oxalic acid concentration, temperature, stirring rate and particle size on the dissolution rate of synthetically prepared calcium molybdate were investigated. Dissolution of calcium molybdate in oxalic acid solutions takes place as a series - parallel type reaction. In the first reaction step, which proceeds according to the ""Langmuir - Hinshelwood Mechanism"", calcium aqua oxalato molybdate is formed as a complex chelate intermediate product. In the second reaction step, molybdic acid is formed during the slow hydrolysis of calcium aqua oxalato molybdate, and it reacts rapidly with oxalic acid to form the polymeric hydrogen oxalate dimolybdate chelate as an end product. Activation energies were calculated as 41.4 and 49.9 kJ mol-1 for the first and zero order reactions. The fractional conversion versus time relationship can be given by the following equation.IntroductionMolybdenum is used widely in electric-electronic, metal working, aerospace and aeronautic, nuclear, glass and petrochemical industries because of its high melting temperature and resistance against chemical effects. However, the largest molybdenum consumers are the iron-steel and super alloy industries where molybdenum is used as an alloying element. Industrially important molybdenum minerals are limited to molybdenite (M0S2), powellite (CaMo04) and wulfenite (PbMo04), which are considered as primary molybdenum resources. Secondary molybdenum resources are spent catalysts and scrap [1-4].Molybdenum has been produced by pyrometallurgical processes in the past. Since it is possible to process low grade molybdenum ores and industrial wastes by hydrometallurgical processes, which are more environmentally friendly than pyrometallurgical processes, the importance of the use of hydrometallurgical processes has increased in the molybdenum production industry."

Jan 1, 2012

By Norbert Hort, Karl Ulrich Kainer, Carsten Blawert, Daniel Fechner

"With the development of new heat resistant magnesium alloys, the automotive industry has introduced several parts to the drive train. The rising number of large magnesium components will result in a higher quantity of automotive post consumer scrap and the changing legislation will force car manufacturers to take magnesium recycling into consideration. So far post consumer scrap has not been used for magnesium alloy production. Quite a reasonable amount of automotive scrap is likely to end up in a mixed light metal shredder fraction. The separation of mixed magnesium scrap according to several alloys is complex. Therefore secondary magnesium alloys made from blended post consumer scrap would be useful. For this work a matrix of potential recycling alloys was prepared by chill casting and high pressure die casting. The materials were investigated for their microstructure, mechanical properties, heat resistance and corrosion properties. The results will be presented in this paper.IntroductionWithin the last ten to fifteen years several heavy magnesium parts have been assembled in passenger cars, such as gear box housings and crank cases [1, 2]. Reasons are the lately developed new heat resistant alloys and the increasing responsibility of automotive manufacturers to reduce the vehicles weight and thereby CO2 emissions. The latter is pushed by international legislation [3, 4]. The rising quantity of magnesium in automobiles will result in an increasing amount of so called post consumer scrap at the end of the vehicles life.So far magnesium recycling was done only for clean scrap that is free from impurities, contaminations and sorted according to a chemical composition or a single alloy respectively [5- 15]. The latter is also called class 1 scrap and mainly consists of sprues and runners from magnesium die casters [15, 16]. For the upcoming automotive post consumer scrap the materials quality strongly depends on the way end of life vehicles are treated. By proper dismantling of old cars, the bigger magnesium components could be collected and possibly treated similar to class 1 scrap [15]. Up to date automotive manufacturers have no uniform recycling system for end of live vehicles. Most probably a considerable quantity of old cars will be shredded. The resulting light metal shredder fraction will contain aluminium and magnesium scrap, both from several alloys. A separation of mixed magnesium and aluminium scrap is feasible according to [17]. Other authors claimed that the grade of separation of magnesium from aluminium is still not sufficient for a proper industrial recycling process of magnesium post consumer scrap [15, 16]. If an automatic sorting is possible it will probably be very expensive [18]. Therefore, so far the main use of post consumer scrap has been the steel desulphurisation and aluminium production [15]. The use of post consumer scrap for magnesium alloy production has been considered already by [15] and [16] but some problems have to be approached."

Jan 1, 2008

By Edmundo Manilla, Merete Tangstad, Daniel Davila, Eli Ringdalen

FeMn alloys are typically produced with lumpy ore or sinters. Minara Autlan, the Mexican FeMn producer, is however making Mn-nodules as a raw material for Mn-alloy production. The Mn nodules have been characterized by XRF, XRD, by wet chemical methods and by EPMA. The Mn/Fe ratio is somewhat lower compared to commercial Mn ore on the marked. The basicity of the ore is however close to 1, and additional fluxes may not be used. The Mn-nodules will be in a state of manganosite (MnO), tephroite ((Mn, Ca)2SiO4) and galaxite ((Mn,Mg)Al2O4). This leads to a low melting temperature area. A low porosity and low amount of higher Mn-oxides gives a high thermal strength to the nodules.

Jan 1, 2016

By ZhiLong ZHAO, Lin Lin, Zhancheng Guo, Jingtao GAO, Huiqing Tang

Grain sticking often occurs in the fluidized bed reduction of f ine iron ore, which is closely related to the precipitation morphology of metallic iron on the surface of ore particles. In this work, simulating the gas-solid reduction process of iron ore, in situ observations were carried out to investigate effects of doping mineral oxides on the precipitation morphology evolution of metallic iron during reduction of iron oxides with CO. Results indicate that the precipitation morphology of metallic iron is related to the quantity of doped mineral oxides. The minimum mole fraction of doped oxide ( xyOA N ) that can inhibit the growth of iron whiskers is related to its cation radius ( Ax r ), extranuclear electronic layers ( Ax n ) and valence electrons ( Ax q ). Their relation can be expressed as:

Jan 1, 2016

By K. Yarnaguchi

In the Mitsubishi Continuous Copper Converting Furnace, calcium femte slag is used. Due to its extremely high basicity, the improvement of corrosion resistance of the refractory lining is in need. In order to clarify the corrosion mechanism and to search for a new corrosion resistant material, first, the surface snuctures of bricks corroded in molten slags were observed by EPMA. Second, the dissolution behaviors of sintered MgO-based pellets containing various oxide additives were examined. It was found that the formation and the dissolution of magnesiofemte at the surface of the bricks play an important role in their corrosion and an addition of NiO, Mn02, or Ti02 to MgO is effective in stabilizing the magnesio-femte and improving the corrosion resistance of MgO.

Jan 1, 1994

By Luis G. S. Sobral, Gabrielle N. Bard

Copper sulphides Concentrates, from the flotation process of copper primary ore; contain, commonly, small amounts of precious metals, such as gold and silver. During the smelting process of those concentrate all gold and silver are practically in the blister copper, which is cast into anodes. Those copper anodes are electrorefined in an electrolytic system, where the electrolyte is an acid copper sulphate solution, where a high purity electrolytic copper is produced (>999,9/1000). The slime when submitted to an oxidative leaching process, using sodium hypochlorite and hydrogen peroxide as oxidizing agents, turn those metals into solution. This research practical work, apart from concentrating effort on the digestion of the anode slime, aims at evaluating the efficiency of the cementation process of the metals of interest for the separation of them to take place. 141

Jan 1, 2008

By Benjamin Vidales

Copper in concentrations above 0.5 weight percent in iron and steel causes hot shortness. This tendency is intensified in the presence of dissolved tin above 0.05 weight percent in the alloy. The understanding of the mechanism of removal of copper from molten iron and steel is of industrial importance. In this investigation, we present the experimental results of the removal of copper from molten iron using sulphide flux in the temperature range 1000°-1500°C. The solution thermodynamic properties of binary sulphide melts have been estimated by using the relevant phase diagrams and the behaviour of copper sulphide in these melts is discussed. The kinetics and thermodynamics of the removal reaction are also explained and, the experimental results are also reported showing the equilibrium distribution of copper and sulphur in molten iron.

Jan 1, 1995

By M. M. Sadawy

"The increased rate of exploitation of iron ores has resulted in a rapid depletion of high-grade iron ore deposits in Egypt. New iron reserves have to be discovered to secure the iron ore for steel production. This paper aims to study the characterization and magnetic separation of low grade Aswan iron ore. The results showed that Aswan iron ore is composed of oolitic hematite, goethite, quartz and kaolinite. The screen analysis indicated that Aswan iron ore had a uniform distribution of iron and silica in the different particle size fractions and there is no any particle size has high amount of iron or low content of silica. On the other hand the results of dry high intensity magnetic separation illustrated that this technique is not suitable for upgrading this ore.IntroductionIron is one of the common metals used in industry, as well as being the fundamental raw material used in iron-steel industry; products are wide spread even in daily uses. The total iron ore reserves of the world have been estimated as 3 70 billion tones; 160 billion tones is classified as economical, while 210 billion tones as potentially economical [1]. An estimated 98% of the iron ore exploited in the world is used in the manufacture of pig iron and steel, which are non-substitutable backbones of modem society. The rapid increase of world steel production over the last few years have required an equal increase in iron ore production, from 876.8 Mt in 2006 to 948.1 Mt in 2007 [2]. The increased rate of exploitation of iron ores has resulted in a rapid depletion of known high-grade iron ore deposits. This, in turn, has led to a dramatic increase of prices. In the absence of any major new discoveries of high-grade iron ore deposits, mining companies have turned to lower-grade materials to assess their beneficiation potential to expand their production base and beneficiation capacity, in order to satisfy future demand. Egypt is going to face shortage in iron production, consequently new iron reserves have to be discovered to secure the iron needed for the country [3]. Exploitation of low grade ores requires special equipments and techniques for recovery of minerals values. High gradient magnetic separators offer promise and great potential of application both technologically and economically in the processing of fine particles containing weakly or feebly paramagnetic components [4-6]. Within this existing framework, this research was initiated to assess the beneficiation potential of low-grade Aswan iron ore by high intensity magnetic separation."

Jan 1, 2013

By Ehsan Vahidi, Fereshteh Rashchi, Amirhossein Shahnazi

"The pig iron from steel manufacturing plants contains a high concentration of vanadium-bearing materials smelted with iron ore. During the oxidation process of the molten pig iron with oxygen lances, vanadium transfers to the slag. In this research, recovery of vanadium from LD (Linz-Donawitz) converter slag of steelmaking plant was investigated. The leaching residue was characterized by XRD and XRF techniques. The maximum vanadium recovery was achieved at optimum leaching conditions of 70 °C, S/L: 1/15, sodium hydroxide concentration: 3 M and leaching time: 150 minutes. The dissolution rate increased with rising sodium hydroxide concentration and temperature and decreasing particle size. The experimental data are treated graphically to explain the kinetics of the vanadium recovery process using shrinking core model (SCM). As a result, the controlling regimes in the SCM were analyzed separately using liquid film diffusion control, solid product diffusion control, and reaction control mechanisms.IntroductionVanadium is commercially important as a constituent of several alloys and catalysts. Nowadays, vanadium is mostly recovered as a by-product from secondary sources or from industrial waste streams such as titaniferrous magnetite, fly ash, spent catalysts, and petroleum coke. Steelmaking operations are specifically concerned by this problem due to the production of a huge quantity of by-products [1]. These by-products, including LD converter slag, sludge, fly ash, spent catalyst, ash, and alloyed scrap, contain a notable amount of heavy metals which may cause environmental problems. Solvent extraction is one of the techniques being increasingly used for the recovery of vanadium [2]. Apart from vanadium ore, secondary resources such as titanmagnetite, ilmenite and slag from the ferrous industry are a major source of supply. The pig iron from steel manufacturing contains a majority of vanadium-bearing materials smelted with iron ore. In a heat resistant shaking ladle the molten pig iron is oxidized with oxygen lances, causing the vanadium to be transferred to the slag. Normally, the vanadium in LD converter steel slag (coming from Linz-Donawitz steelmaking process) is ca. 5% as vanadium pentoxide (V2O5). This slag is the world's principal raw material for vanadium production [3, 4]. Moskalyk and Alfantazi [4] reported that a roast-leach process is used in South Africa for the production of vanadium oxides from magnetite ores while some of the slag was converted to ferrovanadium. A portion of the slag was exported to Europe for the production of vanadium oxide. The researchers mentioned that alkaline roasting was the main process at that time employed to extract vanadium pentoxide from vanadium slags."

Jan 1, 2012

The copper concentrate market is becoming increasingly unstable. In the early 1990s large concentrate stocks were built up and the glut was cleared only after treatment charges rose so sharply that 'non-traditional' custom smelter capacity, such as in Kazakhstan, could be employed, By 1994 the market had shifted and Western smelters were unable to secure enough concentrates to operate full out. The reason for these sharp swings in the market balance is that virtllally all the recent mine development has been non-integrated. With different companies developing new mine . and smelter capacity, it is inevitable that the pace of expansion in the two sectors will not be coordinated. For many years the Japanese smelters were the major buyers from the new mm-integrated mines. However, Japanese smelter capacity is unlikely to increase appreciably in the future and this stabilizing influence will be very difficult to replace. This paper will examine the likely concentrate/smelter balance over the next five years and will forecast the likely direction of? treatment charges. It will also touch on the critical variables in assessing the viability of new greenfield custom smelter capacity, such as proximity to concentrate sources, by-product sulfuric acid prices and, most importantly, tariff protection.

Jan 1, 1995

By A. S. Mustafinova, A. A. Zharmenov

"Production of electrolytic copper is characterized by large volumes of acidic spent solutions the utilization of which requires considerable expenditures of neutralizing agents. At present, an economically substantiated technology does not exist for treatment of sulfuric acid rinse solutions and spent copper electrolyte which will allow for repeated use of the acid and the metal salts. Therefore, for this aim the most advantageous is the use of electromembrane methods. In the paper there is stated the essence of developed technologies which are distinguished by low waste and provide the extraction from the solutions of metallic copper, nickel and sulphuric acid. There are also considered methods of copper electrolyte processing allowing to regulate its composition by that or another component (H2S04, Cu, Ni, As).On the base of the detailed study of the behaviour of various types of ion- exchanger membranes in copper-, nickel-, zinc-, arsenic- bearing sulphate solutions there is realized the selection of the most suitable membranes (MK -401, MA-411, MB-2 and MKL-l/MAL-2).Some variants of electro membrane processing of spent solutions of the hydrometallurgy process have passed productions tests on a number of copper-electrolyte enterprises of the countries of CIS (cooperation of Independent States). These tests showed high efficiency of developed methods."

Jan 1, 1997

By Tracy Morris, Weldon Read, Luis Navarro

"Bismuth is a recognized contaminant in the electrolytic refining of copper that can render many cathodes to be outside ASTM standards and unsuitable for copper rod and other downstream products if not carefully controlled. This paper portrays the performance of Molecular Recognition Technology (MRT) for bismuth removal at the Amarillo Copper Refinery (ACR) and describes how the highly selectivity gel has been successfully used to achieve good bismuth removal and how many pit falls and draw backs have been overcome.IntroductionASARCO operates one of the largest copper refineries in the world at Amarillo, Texas. The main feed for this refinery is produced at the Hayden smelter in Arizona. During the operation of this smelter a variety of metals are carried as impurities in the copper anodes because of the diversity of concentrates and residue products used as raw materials in the smelter feed mix. Even though the impurities are concentrated enough to be detected at the smelter, it is difficult to remove them completely. A simple way to control impurities at the smelter is to minimize the addition of material with a high concentration of impurities to the charge in order to reduce the output of this metal species. All this leads us to have a ""refinery problem"" [1,2,3]."

Jan 1, 2012

By W. L. Dalmijn, E. A. Schokker, N. Fraunholcz, P. C. Rem

Many processes developed for the mechanical processing of Automotive Shredder Residue (ASR) suffer from high processing costs. We offer a distinct concept for low-cost mechanical processing still allowing high value-added recycling of the recovered materials. The basic idea behind this approach is to produce saleable pre-concentrates at the lowest possible costs that can be further processed in existing separation facilities. Our process includes screening, size reduction and magnetic separation. Preliminary studies showed that fibers in ASR are magnetic due to adhering rust particles allowing separation into a fiber fraction and a non-magnetic rigid fraction by high-intensity magnetic separation. The fiber fraction is most suited for thermal processing. The rigid fraction mainly consists of plastics and rubbers with up to 10 wt.-% of non-ferrous metals, some inert material and copper wires. This fraction is very well suited for mechanical processing by, e.g., sink-float separation in existing metal separation plants. The non-metal fraction can be processed further to recover the plastics and rubbers. The process proposed in this study is expected to be substantially cheaper than full thermal processing. In addition, as it mainly relies on existing separation facilities, it can be applied in the short term.

Jan 1, 2000

By He De-wen

The increasing population and living standard in urban areas, have been accompanied with the growing quantity and composition complexity of rubbish, which are causing well-known social effects of pollution, while rubbish (solid waste) is a recyclable resource. To convert rubbish into useful materials, the essential measure is to carry out sorted collection of rubbish. The preconditions of implementing sorted collection are presented in the paper. 1 Characteristics of rubbish composition and amounts of recyclable contents are basic condition to implement sorted collection. 2 The existing available technologies of recycling, economic benefit from recycling, and disposal scheme of residual rubbish are restrained condition for sorted collection. 3 Public understanding and support to sorted collection are the key to success. 4 The government policies to be favorable for sorted collection is the pledge of success. 5 The establishment of a steady solid waste recycling market is also a guarantee to implement sorted collection continuously. 6 To establish management system of rubbish recycling as soon as possible. Further, the methods and procedure of sorted collection are discussed in detail and beneficial comments and theoretical basis to promote sorted collection of rubbish in urban area are presented; it will contribute reference value to municipal solid waste management.

Jan 1, 2006

By Maria Cristina Ruiz

The removal of iron from the leaching circuits is a common problem in the hydrometallurgical processing of non ferrous metals. Among the currently available processes, hematite precipitation is the most recommendable from an environmental point of view. This paper is concerned with the batch precipitation of hematite from ferrous sulfate solutions. One of the main objectives of the study was to determine the effect of the experimental conditions on the extent of iron precipitation as well as the purity and the particle size distribution of the precipitates. The main variables studied were temperature (180 to 220 ºC), concentration of sulfuric acid (1 to 10 gpl), initial iron concentration (1 to 15 gpl) and partial pressure of oxygen (3 to 7 atm). The results showed that increasing the oxygen partial pressure from 3 to 7 atm produced a very small increase on the rate of hematite precipitation indicating that a large partial pressure of oxygen is not needed for an effective ferrous to ferric oxidation. An increase in the temperature produced finer precipitates with lower sulfur contents. On the other hand, an increase in sulfuric acid concentration and initial iron concentration produced precipitates with larger particle sizes and higher sulfur contents.

Jan 1, 2006

By G. A. Brooks

The problem of treating concentrates with increasingly higher levels of arsenic and antimony is compounded by the trend to stricter environmental guidelines regarding the disposal of smelter wastes. Much of the arsenic and antimony from non-ferrous processes is recovered as oxide fume. The options for handling these fumes include recycling them to the smelter, stabilising and disposing of them, and recovering values from them. Whilst arsenic oxide has little value, there is a market for antimony oxide and this provides an incentive for devising techniques for separating antimony oxide from arsenic oxide before disposal of the arsenic oxide. Arsenic can be separated from antimony oxide by selectively volatilising the more volatile arsenic trioxide from a mixed oxide sample or by selectively condensing the less volatile antimony tetroxide at high temperatures, leaving arsenic trioxide to condense out at lower temperatures. The results of selective volatilisation experiments at 379 to 587 °C indicate that it is difficult to achieve an arsenic content below 5.0 wt.% using air or nitrogen as carrier gas due to the formation of solid solutions between the two oxides. Injection of oxygen into a mixed vapor stream improved separation by selective condensation and antimony tetroxide containing as low as 0.23 wt.% was obtained in laboratory experiments.

Jan 1, 1994

By J. E. Dutrizac

Mineralogical studies were carried out on nodulated copper cathodes from three primary refineries to characterize the nodular growths and to elucidate the causes of the nodulation. Nodulation is often initiated at the surface of the starter sheet or the stainless steel plating blank, although a layer of smooth copper sometimes is deposited before nodulation commences. In some instances, the "roots" of the nodules exhibit a pronounced dendritic texture that is associated with an abundance of cavities. Slimes particles are not usually associated with these growth features which lead to a globular surface deposit. The globules sometimes develop into larger nodules, and this type of nodulation is likely caused by improper addition agent concentrations. The nodules on most cathodes, however, exhibit "roots" at the contact with the substrate that are associated with microcavities and large clusters (>40 µm) of slimes particles. The slimes constituents are commonly Ag powder, PbSO4 and Cu2(Se,Te) but not AgCu(Se,Te) or Ag,(Se,Te). The size of the slimes clusters, rather than their composition, appears to be the important factor causing the copper to grow into nodules. Tiny individual slimes particles themselves do not appear to cause cathode nodulation.

Jan 1, 1999

By Dirce H. Jacomo, Jaciele G. Teixeira, Anibal Y. Abreu Castillo, EsperidianaA. B. Moura, Yalquiria A. Silva, Rene R. Oliveira, Michelle G. Gomes

"Composites consisting of poly(vinyl alcohol), starch and sugarcane bagasse ashes, using glycerol as plasticizer agent, were prepared by solution casting method. Composites prepared were subjected to electron-beam radiation treatments, at radiation dose of 50 and 80 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The composite samples obtained were evaluated for their water absorption, mechanical and morphological properties.1. IntroductionThe potential of biodegradable polymers and more specifically of biocomposites obtained from agro-resources have long been well established [1-3]. Starch, derivate from variety of botanical sources (cereals, legumes, and tubers) is widely available raw material and one of the most studied and promising agro-resources for the production of biodegradable polymers as matrices for biocomposite applications. However, starch itself is very brittle, hydrophilic and its mechanical properties are very poor for many applications [3 - 5]. The blending of starch with conventional polymers is a promising approach to improve its drawbacks. Recently, many efforts have been made to blend starch with biodegradable synthetic polymers [5, 6]. Polyvinyl alcohol (PYA) is a particularly well-suited synthetic polymer for the formulation of blends with natural polymers, as it is highly polar and can also be manipulated in water solutions, and depending upon its grade, in functional organic solvents as well [3, 7]. PY A has been reported to be an option to blend with starch. Most of the starch/PY A composites have been prepared by casting. However, it is well known that starch/PY A composites has poor in water resistance and mechanical properties after absorbing water [3,8]. Attempts to improve the mechanical properties and to decrease the water absorption property of the starch/PY A composites are made by adding the cross-linkers and plasticizers. Park et al. prepared starch/PY A/citric acid films by the casting method. They also studied the effect of (spell out) citric acid on the mechanical properties and water resistance of composites [9]. Zhai et al. prepared the starch/PY A hydrogels using electron-beam radiation [10]. Different kinds of lignocellulosic fibers have been investigated in blends for formulation of biocomposites."

Jan 1, 2013