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By C. A. Landolt

Inco pioneered the use of tonnage oxygen in non ferrous metallurgy when it commissioned the first industrial oxygen f1ash smelting process for the treatment of copper concentrates in the ear 1y fifties. This techno logica1 innovation was followed by other applications of technical oxygen. Inco is currently implementjng a Sulfur Dioxide Abatement Program designed to reduce SO2 emissions from the smelter by 60% in 1994. The new flowsheet includes new equipment for the oxygen flash smelting of Cu-Ni concentrates and for flash conversion of chalcocite. Oxygen smelting and converting technology will lead to a substantial decrease in use of fossil fuels and to generation of high strength S02 off gases suitable for efficient fixation in a new acid plant.

Jan 1, 1992

By C. A. Landolt

Inco pioneered the use of tonnage oxygen in non ferrous metallurgy when it commissioned the first .industrial oxygen flash smelting process for the treatment of copper concentrates in the early fifties. This technological innovation was followed by other applications of technical oxygen. Inco is currently implementing a Sulfur Dioxide Abatement Program designed to reduce S02 emissions from the smelter by 60% in 1994. The new flowsheet includes new equipment for the oxygen flash smelting of Cu-Ni concentrates and for flash conversion of chalcocite. Oxygen smelting and converting technology will lead to a substantial decrease in use of fossil fuels and to generation of high strength S02 off gases suitable for efficient fixation in a new acid plant.

Jan 1, 1992

The purpose of this study was to investigate the immobilization as a host for metallic pollutants (Cr, Cu, Pb, and Zn) by ettringite phase. Ettringite phase is produced through hydration reaction of calcium aluminate with gypsum. From the XRD patterns, it is known that the distance between spaces in 010 planes in ettringite crystal increase with an increase of ionic radius of heavy metal except Pb; no big difference is shown. For this reason, the d-value of 010 planes in ettringite crystal increased with the substitution of Cr, Cu and Zn having a big Al ironic radius. But in case of Pb, because the substitution occurred at calcium site, it does not influence to increase d-value of 010 planes.

Jan 1, 2006

By Xiaowen Liu

The DSC/TG, IR and XRD analysis were used to characterize the heating phase transformation of illite, which came from Ouhai deposit, China. It was discovered that the dehydration and de-hydroxylation of illite carried out stage by stage during heating. The adsorptive water and layer-inter water were dehydrated from room temperature to 500°C; and dehydroxylated in the range 500°C~800°C. In these stages of process, illite?s layer structure kept almost unchanged. After 800°Cillite began to change into disorder structure. At about 1100°C, the layer structure of illite had been destroyed, and amorphous SiO2 and mullite crystallite appeared. At about 1200°C the structure of illite completely destroyed and mullite crystal phase had become perfect..

Jan 1, 2006

By Jilai Xue

Fe-Ni alloys can be used as raw material in making stainless steel. Laterite nickel ore is one of mineral resources for producing nickel alloys. In this work, the laterite ore after dehydration at 800 °C and the anthracite as reducing agent were mixed for pre-reduction at 900 °C, and then reduced to form Fe-Ni alloys at 1550-1620 °C through carbon-thermal reduction process. A high Ni-content alloy component in the metallurgical mixture can be formed through pre-reduction. Better separation of the resulting metals from the slag is found with lower Ni-content alloys produced or higher temperatures during reduction. An effective processing of Fe-Ni alloys needs further understanding of the process fundamentals and optimizing of the process parameters.

Jan 1, 2010

By Cheng Gong-jin, Chu Man-sheng, Liu Zheng-gen, Zhang Yong, Liu Jian-xing, Xue Xiang-xin

"High chromium vanadium-titanium magnetite is one kind of Fe-V-Ti-Cr composite ore resources, which owes high utilization value. Owing to lacking systematic study on the sintering of this ore home and abroad, effects of carbon addition and basicity on sintering process and sinter metallurgical properties, such as sinter yield, vertical sintering speed, tumbler strength, sinter machine utilization coefficient, and low temperature reduction degradation were investigated systematically under laboratory conditions in the paper. The results shows that, when high chromium vanadium-titanium magnetite proportion is kept unchanged as 13% in sintering feeds, sintering process index and metallurgical properties are the optimum under carbon addition 5.0% and basicity 2.70, which meets the requirements of blast furnace burdens. This research provides technical parameters for practical sintering production of high chromium vanadium-titanium magnetite.IntroductionHigh chromium vanadium-titanium magnetite (hereinafter abbreviated as hi§h-Cr V-Ti magnetite), in which Fe is closely symbiotic with Ti and isomorphous with V and Cr1'- l, is one kind of typical vanadium-titanium magnetite resources with high comprehensive utilization value but the difficulties are extremely high due to complex chemical composition and mineral structure. At present, the feasible and mainstream utilization process of high-Cr V-Ti magnetite should be the route of agglomeration-blast furnace smelting. Thus, sintering production is the foundation for high-Cr V-Ti magnetite utilization. However, till now there are few research documentations on high-Cr V-Ti magnetite sintering home and abroad. Under the above background, this study focused on detailed researches of high-Cr V-Ti magnetite sintering. Sintering process uses the powders or fine iron ores to produce artificial rich ore with good metallurgical properties 4l Solid fuel provides 90% heat requirement during sintering15J. The appropriate amount of fuel and flux should be added during sintering in order to provide necessary heat and maintain the desired basicity16l. That is to say, carbon addition and basicity are two key factors affecting metallurgical properties of sintering products17J. Therefore, the effects of carbon addition and basicity on sintering process and metallurgical properties, including sinter yield, vertical sintering speed, tumbler strength, sinter machine utilization coefficient, and low temperature reduction degradation, are systemically investigated under laboratory conditions in the study, on purpose to achieve the optimization of sintering process for high-Cr V-Ti magnetite."

Jan 1, 2013

By Frank Field, Elsa Olivetti, Randolph Kirchain, Elisa Alonso, Gabrielle Gaustad

"The primary technological challenge to increased use of secondary raw materials is the presence of undesirable elemental species in scrap streams. Recent literature indicates that this may become exacerbated by accumulation of impurities over time. Devising strategies to mitigate this problem depends upon understanding the mechanisms of accumulation. This paper takes a first step at characterizing the extent of this issue by presenting a simple analytical model of recycling rate for materials experiencing exponential growth. Low potential recycling rates limit accumulation due to dilution. Empirical analysis of several major materials indicates that, even for current recovery rates, theoretical recycling rates can reach above 60%, making accumulation issues a possibility.IntroductionIt is well known that recycling of secondary materials can provide significant environmental and economic benefits. Energy savings, in particular, can be quite large when substituting secondary materials for primary. Nevertheless, over the past decade, the recycling rates within the U.S. of many materials appear to not be increasing as rapidly as one would predict or even at all (Figure 1). While many barriers exist to increasing materials recycling, one that is cited consistently by the literature and producers[1-3] is compositional limitations; that is the mismatch between the characteristics of secondary materials and those desired for the finished goods into which they would be transformed..One particular aspect of compositional limitations that is receiving increasing attention is the potential for progressive deterioration of the quality of secondary raw materials streams. For some materials, for example paper or polymers, this phenomenon is inherent and relatively rapid[4, 5]. As such, it is well documented and plays a significant role in recycling decision-making even for prompt or in-house material recycling. Conceptually, this issue can manifest in other secondary materials as well, albeit through a different mechanism.As materials are mixed, used, and reprocessed during recycling, they come into contact with and often pick up other elements. The presence of these, so-called, tramp elements alters the original known composition, possibly requiring additional measurement and processing and may even preclude economic, productive reuse; ultimately, this unintentional pick up is unwanted. A growing number of studies and literature would suggest that accumulation of unwanted elements is an emerging problem, in most recycled material streams. Table I provides a brief literature review of various recycled material streams and the accumulated elements noted as problematic by various authors"

Jan 1, 2008

By Robert F. Jenkins, King G. Robertson

This paper presents a practical approach for utilizing a computer model to determine the mass balance for a typical UBC recycling complex - starting with raw materials input, through scrap preparation, delacquering, melting, alloy adjustment and casting. This model is especially concerned with metal unit losses throughout the recycling complex with emphasis on metal losses at the melting furnace. The model also addresses the application of hardener alloys, metallurgical salts, chlorine for demagging, and reagents for acid gas emissions control. Other issues addressed are dross generation, acid gas emissions and dirt and fines to landfill. One benefit of the model is the conversion of annual production objectives to hourly production rates and resource requirements taking into account production schedules, maintenance downtime, and operations inefficiencies.

Jan 1, 2000

By He De-wen

The influence of coal desulphurization by fungus was experimentally studied. The present results suggest that fungus can effectively remove inorganic and organic sulfur in coal. The main factors that influence the desulphurization by fungus such as pH value, temperature, coal slurry concentration and coal granularity are studied by orthodox experiment and the optimal experimental conditions are as follows: pH value 6, temperature 45 C, coal slurry concentration 10% and coal granularity 100 m. Under the above conditions, fungus can remove up to 44.96 total sulfur and 54.87 inorganic sulfur within two days and their desulphurization rates will increase along with time. Compared to sulfolobas, desulphurization by fungus is steady and more effective and has the advantage of high speed.

Jan 1, 2006

By M. F. Chambers

Neodymium metal was electrowon from a molten-chloride electrolyte at 650° C using a molten-metal cathode. A 50 mol pct NdC13-50 mol pct KC1 mixture served as the electrolyte. Binary metal alloys of 'Mg with Zn and Mg with Cd were used as molten cathodes. Under the best conditions, current efficiencies were 90 pct with a Mg-Zn cathode and 80 pct with a Mg-Cd cathode. Vacuum distillation was performed at 1,100° C for 30 min under a vacuum of 10-3 to separate the cathode metals from the neodymium. Neodymium metal of 99.9+ pct purity was recovered from the Mg-Cd alloy cathode. Almost 2 pct zinc remained in the neodymium recovered from the Mg-Zn alloy.

Jan 1, 1989

By J. Murphy

The economics of microbial coal desulfurization are affected significantly by the proper selection of the plant site and by maintenance of variables at suitable levels. High sulfur coal particles below 200 mesh show sulfate production rates triple those with 150 mesh coal but grinding costs are greater. Slurry solids density increases from 5% to 20% reduced the rate constant by a factor of 10. Coal added to a batch reactor in the stationary phase resulted in a sudden second exponential sulfate production phase indicating feasibility of lower cost continuous operation. Successful operation in the absence of beef broth, yeast or added nutrients at non-sterile conditions enhanced projected economics. Finally, the need for adequate agitation and aeration was well established.

Jan 1, 1985

By Yonggang Liu

Microstructure and precipitates in hot rolled low carbon steel sheet by CSP were investigated in this paper. It is pointed out the precipitates in low carbon steel sheet by CSP are different with that by traditional hot rolling. The bainites were found in CSP hot rolled steel sheet by TEM testing and these bainites could maintain in the sheets even after batch annealing. The selected area electron diffraction analyzing indicated that there were many CrB2BN and FeB4BN phases precipitated in hot rolled steel sheet and no AlN grains precipitated. The nitrides forming can limit AlN grains precipitating during the batch annealing processing, and this could do harm to the texture pipeline along orientation line forming with formed properties.

Jan 1, 2006

By Ian Baker, Xavier Pierron

"Iron aluminides hold great promise for intermediate temperature applications (to ~ 600°C) because of their excellent oxidation and sulphidation resistance and good strength. However, they have poor low temperature ductility, a feature which is exacerbated by water-containing environments. This paper presents an overview of the effects of environment on the ductility of iron aluminides, including the effects of iron aluminum ratio; ternary alloying additions, particularly boron; strain rate; and temperature. The mechanisms involved in water-induced embrittlement are discussed.IntroductionOver the last few years, it has became increasingly evident that the ductility and fracture toughness of many intermetallic compounds, particularly aluminides, are reduced dramatically if they are mechanically tested in either air or in hydrogen-containing atmospheres (1-5). For FeAI and Fe3AI, it has been shown that water vapor, for example in air at room temperature, can form atomic hydrogen by reacting with the Al atoms (1, 2). As a result in iron aluminides, the environmental embrittlement process is quite similar to traditional hydrogen embrittlement. This can be easily demonstrated by either testing an iron aluminide in an environment free of the deleterious species or by testing at high strain rates, both of which result in greater ductility. The purpose of this paper is to review recent progress in understanding environmental embrittlement in FeAI and Fe3AI, and to consider possible environmental embrittlement mechanisms. Greater understanding of this phenomenon will lead ultimately to remedies to this problem which is a major reason for preventing the practical application of these materials. First, some background on the iron-rich aluminides."

Jan 1, 1996

By Zhang Chuanfu, Tan Pengfu

"A thermodynamic model is developed to predict the distribution behaviors of Ni, Co, Sn, Pb, Zn, As, Sb, Bi, Au and Ag in copper pyrometallurgical process. In this model, as more as 21 elements (Cu, S, Fe, Ni, Co, Sn, As, Sb, Bi, Pb, Zn, Au, Ag, 0, N, C, H, Ca, Mg, Al, and Si) and 72 compounds (in fayalite-slag-making system) or 74 compounds (in ferrite-slag-making system) are considered. Accessory-element behavior is studied for two types of slag , fayalite and ferrite, and two levels of oxidation. The allowance is also made to account for physical entrainment in the melts.-Model simulations are carried out to study the effects of controllable process parameters such as feed composition, smelting temperature, degree of oxygen enrichment and volume of oxygen enriched air. The model can be used in copper flash process, Mitsubishi process and Noranda process. The predictions by the present computer model are compared with the known industrial data from Gui Xi Smelter in China, Home Smelter in Canada and Naoshima Smelter in Japan and excellent agreement between calculations and industrial data is obtained. In this paper, the effects of oxygen enrichment, matte grade, smelting temperature, and types of slag on accessory-element behavior among matte, slag and gaseous phase have been elucidated.I . IntroductionThe presence of trace quantities of minor elements such as As, Sb and Bi in copper significantly reduces its ductility, electrical conductivity, and lowers its thermal conductivity. Embrittlement of copper also occurs due to impurity-phase precipitates at the copper grain boundary interfaces. They deteriorate not only the electrical conductivity of copper but its workability in hot working."

Jan 1, 1998

By Yongzhong Xiao, Tiejun Chun, Jian Pan, Deqing Zhu

"An innovative process of reverse floatation-direct reduction-low intensity magnetic separation was developed to effectively beneficiate the superfine run-of-mine (ROM) ore mined from Hunan Province, China. Mineralogy was measured that the ROM ore is of superfine low grade hematite ore type, assaying 27.2wt%Fetotal and with main valuable minerals of hematite occurring at size between 3 to 5µm. The upgrading results show that the final iron concentrate, assaying 88.3wt%Fe total and 94.5% metallization degree was obtained at an overall iron recovery of 69.9% under the following conditions: rough concentration by grinding of ROM up to 88.7% passing 0.074 mm and reverse flotation at pH=9.4, 100 g/t starch and 200 g/t dodecylamine (DDA), and coal reducing the rough concentrate pellets containing 12% calcium containing complex additive at 1200 oC for 120 min, and finally magnetic separation of the reduced pellets by grinding up to 89.2% passing 0.043 mm at 0.08 T field intensity.IntroductionWith the rapid development of iron and steel industry in China, there has been a soaring demand for iron ores in the past decade. The imports of iron ores have increased from 148 million ton in 2003 to 628 million ton in 2009 [1]. Iron making industries increasingly demand for high grade raw materials to improve product quality and reduce operation cost. However, availability of high grade natural ores is limited and enrichment of lower grade ores is necessary to meet the demand. Therefore, large quantities of superfine low grade iron resources are necessary to utilize in China at the moment."

Jan 1, 2011

By Wen Chen, Xinghua Liu, Zeyou Peng, Qiulin Wang

"Limonite is a collective for iron hydroxide argillaceous materials. It is very difficult to be treated due to the wide variation in specific gravity and magnetism and the high argillization rate in the course of grinding and beneficiation. The iron ore in Huangmei, Hubei, China is the typical representative of limonite. If the limonite is processed using conventional physical beneficiation methods (e.g. magnetic separation, gravity separation, flocculation-desliming-flotation, or a combined process of the three), it can only be obtained an iron concentrate grade of 51.98% and an iron metal recovery of 86.64%. However, the technique of flash magnetic roasting-magnetic separation can improve the concentrate grade to 61.03%, iron recovery to 91.17%. This paper describes the tests of recovering limonite by flash magnetic roasting in detail.IntroductionLimonite (mFe2O3, nH2O)[1] is a general designation for hydrous iron hydroxides and argillaceous matters. Limonite is hard to be separated because of its complicated geneses, comparatively weak magnetism, nonuniform grain size and being easily slimed during grinding. So most small and medium enterprises sell deslimed limonite product which was dealt with just by simple methods of washing, magnetic separation or gravity separation and so on. In recent years with the iron ore prices soaring, significant progress was made in mineral processing research of limonite. Laboratory research and industrial test results showed that flocculation-desliming-flotation process and roasting-magnetic separation process are the two best methods to recover limonite till now. To compare these two methods, roasting-magnetic separation process is superior to flocculation-desliming-flotation process in aspects of beneficiation indexes and industrial stability."

Jan 1, 2012

By Alex Luyima, Honglan Shi, Lifeng Zhang, Yongqing Jiang

"Leaching process has been suggested to recover most metals from waste PWBs. In this study, the leaching behavior of most metals present in waste PWBs is evaluated before and thermal treatment. Different leaching acids: hydrochloric acid (HCl), nitric acid (HNO3) and aqua regia are compared. The effects of acid concentration, particle size of sample, leaching time and temperature are examined. Results revealed that most metals are present in small particle size and sequential leaching of PWBs with a combination of HCl acid and aqua regia is capable of dissolving most of the metals content of PWBs. Leaching of thermally treated PWBs produced the highest leaching percentages for similar leaching conditions.IntroductionApproximately 20–50 million tonnes of electronic waste (e-waste) is produced globally per year. Waste Electrical and Electronic Equipment (WEEE) or E-waste is one of the fastest growing waste streams in the world. In developed countries, it equals 1% of total solid waste on an average [1]. The growing stockpile of used and obsolete consumer electronics has been called the “largest toxic waste problem of the 21st century [2]. Printed wiring boards (PWBs) is an essential part of almost all WEEE, and accounts approximately 3% of all WEEE by weight [3]. PWBs are a platform upon which microelectronic components are mounted. PWBs contain metals (~40 wt. %), ceramics (~30 wt. %) and plastics (~30 wt. %) [4]. The metallic part includes; Cu, Pb, Zn, Fe, Cd, Be, Cr, Au, Pt, Pd, Ag, etc. The plastic part of the PWBs is mostly epoxy resins. These plastic resins also contain very toxic halogenated flame retardants (HFRs) [5]."

Jan 1, 2012

By Taiping Lou

The coarsening process of precipitates in non-equilibrium systems was studied, and then a physical model of coarsening was proposed. The coarsening process of CaO'TiO2 in MgO-TiO2-Al2O3-SiO2-CaO-CaF system was investigated. It is shown that the coarsening process by the model predicting is agreed with the experimental results.

Jan 1, 2000

By R. G. Robins

The effective removal of arsenic(V) from process streams and waste waters by precipitation with excess iron(II1) is sometimes attributed to the formation of basic ferric arsenates. The authors have investigated this system extensively using a variety of techniques and conclude that the solid phase produced is iron(II1) oxyhydroxide (ferrihydrite) with arsenic(V) adsorptively bound to the 2-3 nm particles.

Jan 1, 1992

By Julian Szekely

Transport phenomena, that is heat transfer, mass transfer and fluid flow, play a critical part in the operation of metallurgical reactors. In this paper, we shall present a review of our current state of ability to model these systems mathematically, with emphasis on the use of computational codes that are generally accessible to the public and on the comparison of the theoretical predictions with measurements.

Jan 1, 1993