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By K. A. Dudley

Basic solvent extraction theory indicates that pH initiates the basis of an oxime's metal complex formation and therefore its selectivity toward certain metal species. The recommended optimum pH for some of the commercial copper reagents is in a range that should maximise copper loading of the oxime. However, this pH range also tends to maximise iron(III) loading under certain operational conditions resulting in low selectivity values. Recent operational parameters at Girilambone Copper Company have highlighted some of these conditions that have a major influence on the oxime's selectivity for copper over iron(III) in the leach solutions. The result is that the pH for maximum copper extraction is no longer within the optimum range to maximise oxime selectivity. Therefore, specific copper and iron(III) pH isotherms have been determined on-site for the changing leach solutions that are fed to the solvent extraction plant in order to optimise oxime selectivity. The influences of solvent extraction plant configurations are also discussed as a controlling parameter.

Jan 1, 1999

Four slag types covering the range of Fe-Ca-Si-O compositions and two iron blast furnace slags were melted at 1300 °C and doped with 1% of arsenic, antimony, cadmium, zinc and chromium. The melts were either slow cooled or quenched and the solidified slags were leached according to TCLP procedures. The morphology of the solidified slags was characterised using XRD, optical and electron microprobe techniques. Theoretical considerations showed that the capacity of the molten slag to hold the above toxic elements depended upon slag basicity and this was confirmed in practice. The experiments showed that the leaching of the toxic elements was a function of surface area and the phases present, both of which were affected by the mode of cooling. Iron silicate slags produced in nonferrous smelting operations and blast furnace slag from ferrous smelting operations both show promise of being suitable media for immobilising low levels of toxic elements and complying with current regulatory requirements.

Jan 1, 1994

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By M. Okido, O. Takai, Z. Zhao, M. Ishikawa, R. Ichino, K. Kuroda

"Electrolytic method was applied to calcium phosphate coating on titanium plates as an excellent technique for high density and intensive contact of coated films on biomaterials. The effect of H2O 2 as oxidation reagent on coating characteristics was examined to obtain biomineral films. Solution was containing 7.0 X 10·3 mol/dm3 ofCaC12 and 3.0 X 10·2 of Ca(H2PO4)z, kept at 55 ""C. All deposits were hydroxyapatite (HAp) in this study, independent of H2O 2 concentration, applied cathodic potential and solution pH. In the case of H2O 2 addition, an increase in cathode current started at the low potential, namely, ca. -0.2 V (vs. SCE). In contrast, the current increased at more than ca. -1.4 V in the solution without H2O 2 addition. H2O 2 appeared to be an effective reagent for increasing nucleation density and improving adhesion of deposits on titanium plates.IntroductionIn recent years, many researches have been undertaken to develop the techniques of calcium phosphate coating on titanium or bioglass for medical implantation. High density and intensive adhesion of coating are necessary for adding bioaffinity to these materials and for inducing bone morphogenesis on them when implanted in human body.1) Electrolytic deposition has been a newly developed method as high-speed deposition process. By this method, the supersaturation of calcium phosphate can be increased just in the vicinity of metal substrates and the heterogeneous nucleation is promoted on them. In this process, H2O is reduced according to eq. (1) on the cathodically polarized electrode"

Jan 1, 2000

By G. Cifuentes

The kinetics of the electrolytic oxidation of cyanide to cyanate on PbO2-coated stainless steel anodes have been studied by both experimental and theoretical means. The anodes were based on 316 steel and performed in a satisfactory fashion. The pH of the studied KCN solutions exhibited a constant value about 11. Values for all the kinetic parameters have been determined and a mechanism for the studied reaction is proposed.

Jan 1, 1999

By Fu-Shen Zhang, Mengjun Chen, Jianxin Zhu

"A novel approach for foam glass preparation, namely vacuum-aided powder sintering technique, was preliminarily investigated in the present communication. The key point of which was to prepare foam glass at a negative pressure. Compared to normal powder sintering process, the new approach could benefit the foaming process by shorting the holding time, reducing the amount of foaming agent and especially decreasing relative density of the product. Optimum conditions were 750 °C, 1000 Pa, 5 min and 1 wt.% foaming agent, respectively.IntroductionFoam glass represents a highly valuable solution for thermal and acoustic insulation, since it possesses a generally higher mechanical, chemical and thermal stability than other foams'1'. The first industrial processing for foam glass production, the direct introduction of gases (""blowing"") into the special molten glass, can be dated back to the end of 1930s'2'. At present, almost all foam glasses is prepared by powder sintering technique instead of blowing,3 since it reduces the temperature by several hundred degrees. Moreover, as fine glass powders or similar powders can be used to substitute corresponding glasses by this technique, considerable attention has been focused on the production of foam glass by considering fully recycled glasses, coal fly ash, or other solid wastes as raw materials,4 especially CRT glasses'3' 5', on the point of environmental protection.In a previous report'6', when discussing the lead removal and recovery from CRT funnel glass by a pyrovacuum process, we found that foam glass could be prepared at a negative pressure. Therefore, in this communication, the similarities and differences between the powder sintering process for foam glass at normal and negative pressure was preliminarily discussed."

Jan 1, 2011

By B. R. Adams

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

Jan 1, 1999

By Zhenbo Zhao

The processes and equipment for INLRFH (Isothermal Normalizing by Utilizing the Residual Forged Heat) of alloy carburizing steel products are presented. It is shown that four key parameters: namely (I) cooling rate before isothermal normalizing, (IT) the lowest cooling temperature before isothermal normalizing, (111) isothermal normalizing temperature and (IV) isothermal normalizing time, should be controlled. The prediction and calculation of these parameters can be achieved on the basis of components treated and the technical requirements of the steel parts by an on-line expert system. The cost-reductions due to the energy savings resulting from implementing this system for automotive parts heat-treatment are most promising.

Jan 1, 1999

By Zhijing Zhang

The management of hazardous wastes is important in a society which is increasingly concerned with environmental issues. Incinerators such as the slagging rotary kiln are widely used in the treatment of hazardous wastes. However, in order to assure a smooth operation of the rotary kiln, the melt should have both a low melting point and high fluidity. In this study, the fluidity of various hazardous waste rotary kiln slags was measured in terms of length of flow using the crucible test technique. It was found that the slags have melting points ranging from 1372 to 1424°C while their fluidities varied from 61-102 mm. The effect of addition of oxides on the fluidity of a slag containing 47 wt% SiO2 was also investigated. For this slag, additions of SiO2 (up to 56 wt%), FeO and Na20 increased fluidity, whereas the addition of CaO and A1203 resulted in lower fluidity values.

Jan 1, 2002

By Yuanbo Zhang, Huanpeng Mi, Guanghui Li, Binjun Liang, Zhiwei Peng, Tao Jiang

Ludwigite ore has not yet been utilized on an industrial scale due to its complex mineralogy and fine mineral dissemination. In this study, sodium salts were employed to enhance the separation of iron and boron by reductive roasting-magnetic separation. It was found that the separation of iron and boron as well as the iron grade and recovery were significantly improved b y the addition of Na2SO4 or Na2CO3. Under the reduction temperature of 1050 °C, reduction time of 60 min and magnetic intensity of 0.1T. Compared with the inexistence of sodium salts, the iron grade and recovery of the magnetic concentrate increased from 83.3% and 88.6% to 93.2% and 95.1%, respectively, by adding 6% Na2CO3. The XRD and microstructure analyses indicated that the iron oxides were transformed into metallic iron and the average metallic iron grains were grown to over 40μm which was beneficial for separation of metallic iron from gangue.

Jan 1, 2016

By M. Kobashi, T. Choh, N. Kanetake

"A new processing route, which enables the cost-effective and energy- saving fabrication of metal matrix composites, have been proposed. The pressureless infiltration of the reactive powder blend with molten aluminum was investigated in this work. The molten aluminum infiltrated into the [Ti + C] powder blend spontaneously, whereas the spontaneous infiltration into the TIC powder phase did not occur under the same experimental condition. The processing time was shortened and· the processing temperature was .lowered by adding the aluminum powder in the [Ti + C] powder. The differential thermal analysis revealed that the aluminum powder in the powder blend melted at 933K and then ignited the reaction between titanium and ·carbon. However there was an .optimum additional amount of aluminum in the powder blend. The TiC formed in situ had three-dimensionally continuous morphologyIntroductionThe squeeze casting process has been used as one of the processing routes for aluminum matrix composites. [1, 2]. Non-reactive metal-ceramic systems have been, generally, used in this technique in order to prevent the degradation of the ceramic phase. Materials obtained by this process basically consist of a continuous metal matrix and discontinuously dispersed ceramic particles. Reactive systems have begun to be introduced into the infiltration process· recently [3A]. Since the ceramics are synthesized in-situ, this process can provide a continuous ceramic matrix [5]. This is one of the outstanding features of this technique in that a bulk ceramic-can be synthesized at relatively lower temperatures in a short time. Another advantage is that the highly reactive combination of a ceramic with a molten metal is in many cases wettable [6], which enables a spontaneous infiltration."

Jan 1, 2000

By Gordon Irons, Kevin Graham, Krishnakumar Krishnapisharody

Ladle or secondary metallurgy in steelmaking is an essential process step for the production of high-quality steel. Professor David Robertson was a pioneer in the modeling of these processes, in particular gas-metal fluid dynamic interactions and the rates of slag-metal reactions. This is now a highly active area of research, and some of the recent developments in this area will be reviewed.

Jan 1, 2014

By Alwin Frei, Aldo Steinfeld, Peter G. Loutzenhiser, Enrico Guglielmini

"Using concentrated solar radiation as the energy source of high-temperature process heat, the carbothermal reductions of Al2O3 to Al and SiO2 to Si were examined thermodynamically and demonstrated experimentally at vacuum pressures. Reducing the system pressure favors Al(g) and Si(g) formation, enabling their vacuum distillation and avoiding contamination by carbides and/or oxycarbides. Exploratory experimentation in a solar reactor was performed with mixtures of charcoal with alumina and silica in the ranges of 1300-2000 K and 1997–2263 K, respectively, at 10-3 bar by direct exposure to concentrated thermal radiation. Distilled samples contained up to 19 wt% of Al in Al-Al2O3 mixtures and 79 wt% of Si in Si-SiO2 mixtures. When the reducing agent is derived from a biomass source, the solar-driven carbothermal processes are CO2 neutral.IntroductionMetallurgical extractive processes for producing Al1-2 from Al2O3 and Si3-6 from SiO2 are characterized by their high specific energy consumption and concomitant emissions. Alternatively, concentrated solar energy can be used as a high-temperature heat source to drive the carbothermal reductions and, thus, avoid greenhouse gas emissions and other pollutants derived from fossil-fuel-based processes7-12. When the reducing agent is biomass charcoal, the solar-driven carbothermal reduction is CO2 neutral. The carbothermal reductions of Al2O3 and SiO2 are represented by the simplified overall stoichiometric reactions:"

Jan 1, 2011

By Hiroyuki Sano

A closed recycling process for the low-grade scrap of Al-based composite materials was developed. In this process flux treatment with water-soluble halide is a key technique. In the present work, flux treatment conditions were discussed from the viewpoint of the separation and the recovery of the base material, reinforcement and flux. Optimum separation condition was obtained for the NaCl-KCI-KF flux treatment. The recovered aluminum alloy can be recycled for various usages. The recovered SiC particles cannot be reused as reinforcement because of the coexistence of the contamination, therefore it is necessary to eliminate these contaminates or to find another use. The recovered flux is reusable with supplemental addition of fluoride.

Jan 1, 2003

By Jianhong Dong, Min Chen, Cuihuan Huang, Bo Li, Nan Wang

"Scale layer can be formed on the slab surface in the areas of secondary cooling and strand discharge during continuous casting process. From 1000 °C -1200 °C, the influence of steel composition on the stable oxide phases inside scale layer, particularly the types of alloying elements including aluminum, silicon and chromium, is investigated under different partial pressures of water vapor by the calculated predominance diagrams of iron oxide as well as its intermediate compounds formed with other metal oxides, and the stable oxide phase composition within scale layer under the working condition of secondary cooling is discussed. At lower partial pressure of water vapor, only a iron spinel (or ferrosilicate) phase is the stable phase with any alloying element contents in steel composition, whereas the stable phases are FeO and iron spine! (or ferrosilicate) inside the scale layer at higher partial pressures of water vapor .IntroductionOxide scale formation on the surface of cast and rolled products because of oxidation by the surrounding oxidizing atmosphere is a significant disturbance factor in steelmaking. The yield loss of iron because of scale formation is considerable during continuous casting and hot rolling process. Surface quality more often is impaired by scale property, which increasing the difficulty of quality assurance, dimensional accuracy and performance control. Furthermore, a potential source for subsequent surface cracking (hot shortness) can be caused by the enrichment of scrap residuals (Cu, As and Sn) at the steel substrate surface as a result of steel oxidation [1-2]. In flat products manufacture via thin slab casting technologies, these phenomena are particularly pronounced and require enhanced development efforts in descaling efficiency [3].Compared with the scale formation in continuous casting, the quantity of scale formed during hot rolling and reheating in the rolling mill is larger, and control of scale formation and descaling is a long-established task in hot rolling. Therefore, extensive research and development work have been carried out, including the effects of heating and rolling temperature on the thickness and microstructure of scale layer, heating time and furnace atmosphere, cooling mode, and steel composition on the scale formation, more attention has been given to the control of scale formation during reheating and hot-rolling process. On the other hand, hardly any specific efforts and countermeasures are taken in continuous casting, and very less research has been done despite the network-type crack on the as-cast strand surface caused by the subscale enrichment of scrap residuals [ 4-7]."

Jan 1, 2014

By Yoshihiko Maeda

It is said that the 21 st century will be an era of the remedy of the global environment. In order to reserve natural resources for the future and to avoid the dispersion of heavy metals after usage and to avoid pollution problems, it is extremely important to recycle heavy metals as much as possible by reasonable recovery procedures. The nonferrous metal industry is expected to play a important role in the recycling of heavy metals that are originally their products. From the depressed metal price experienced in Japan in 1980th due to the sudden change in current exchange rate between US dollar and Japanese yen, one of major nonferrous metal company, Dowa Mining, has diversified its business area not only to the so-called down stream, but also to the environmental business including metal recycling, industrial waste treatment and soil remediation by utilizing technologies and facilities once used or still used for mining and smelting of copper, zinc, lead and precious metals. In this paper some of these applications will be presented.

Jan 1, 2003

By Jan Yaozhong

The composition and the possible utilization of Ti bearing blast furnace from a titanomagnetite blast furnace smelter were studied. The slag contained about 20% Ti02 and trace Sc. The mineralogical analysis indicated that Ti in the slag is mainly as perovskite. By means of magnetite separation, the Ti containing phase could not be enriched. An effective hydrometallurgical approach was proposed with sulphuric acid leaching. The method proposed for processing the studied slag renders product Ti02 and SC203. Besides the recovery ofTiO2 and SC2O3' the leaching process yields fine grained residues which can used as additives for making cement.

Jan 1, 1996

By John O. Burckle

For years, the measurement of fugitive emissions from the primary copper converter has defied all attempts based on inferential measurements, It has been concluded by virtually all investigators that the only dependable tech¬nique to measure these emissions would be to completely enclose an operating converter to permit the capture and measurement of all emissions. However, complete enclosure with a metal hood is difficult; many of the most serious fugitive emissions result during periods when the converter must be attended with crane-operated equipment. This approach would require either opening of the enclosure to permit the entry of large items of equipment or completely new methods for charging and tapping converters' The installation of the air curtain hooding system at ASARCO's Tacoma smelter has permitted a quantitative approach to the direct measurement of the fugitive for the first time. In this program, the fugitives captured by the air curtain were measured at a downstream sampling point in the exhaust side of the air curtain system during the various portions of the converter cycle. Emission factors were established for sulfur dioxide, filterable particulate (method 5), inhalable particulate, and selected trace elements.

Jan 1, 1983

By Itavahn Alves da Silva, Izabela Diniz Duarte, Carlos Antonio da Silva, Varadarajan Seshadri

Mathematical modeling using computational fluid dynamics has been employed to assess the thermal losses in a steelmaking ladle. Thermal losses lead to thermal stratification and convective flow inside the ladle. The effects of preheating, mineralogical and physical characteristics of the lining as well as thickness of slag cover have been studied and the results obtained from application of the model have been discussed.

Jan 1, 2016