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By K. Alibhai

Greek laterites, which generally had nickel concentrations of < 1 %, are amenable to chemical leaching,. although there is considerable variability in the ease of leaching with different ore types. With low grade ores(< 1 % Ni content); >70% of the nickel was leached in columns with a strong selectivity for nickel over iron. Heterotrophic microbially assisted leaching could be a viable alternative to classical hydrometallurgical and/or pyrometallurgical techniques, with a very high recovery (greater than 80% ) being found with some of these mineral microbial interactions. Critic acid was probably the effective chelating agent.

Jan 1, 1991

By Sergio N. Monteiro

Polymer matrix composites have been applied in components such as helmets and shielding for which toughness is a major requirement. Natural fiber presents interfacial characteristics with polymeric matrices that favor a high impact energy absorption by the composite structure. The objective of this work was then to assess the Izod impact resistance of polymeric composites reinforced with different amounts, up to 30% in volume, of a promising high strength natural fiber from the Amazon region known as curaua. The results showed a remarkable increase in the notch toughness with the amount of incorporated curaua fibers. This can be attributed to a preferential debonding of the fiber/matrix interface, which contributes to an elevated absorbed energy.

Jan 1, 2009

By Xiaowen Liu

The thermal decomposition of diaspore was investigated by thermogravimetry (TG),differential scanning calorimetry (DSC), X-ray power diffraction(XRD),infrared (IR)spectrain this paper. The thermal decomposition mechanism of diaspore was discussed according to Coat-Redfer equation. It was found that the decomposition of diaspore was carried out at 500?,and the peak temperature was 530?. The electrovalent balance of diaspore was destroyed. The previous crystal structure was changed. a- Al2O3 was obtained after thermal decomposition. The activation energy is 287KJ/mol.

Jan 1, 2006

By Guo Chang Jiang

In order to improve the IIAZ toughness of X-60 pipe steel, the intragranular ferrite plate (IFP) technology was used. The characteristics of IFP is claimed to be much fine ferrite plates appear inside the original austenite grains. By means of suitable Re, Zr, Ti additions in a bath with a higher initial oxygen potential, a good control of the peak temperature and the cooling rate during welding simulation, one can get a %IFP in volume over 50%, and the toughness gets up from 55 J to 160 J. It was found that the inclusions most effective in nucleating IFP are some deformable complex silicates which either entrap Re, Zr, Ti oxides or contain these elements. The greater the number of the evenly distributed and effectively nucleating inclusions, the more the %IFP in volume, and the finer the microstructure of the HAZ, so the better the relevant toughness. Generally, these silicates bahave as fine spheres along a line. The present authors revealed that these fine spheres result from the remelting of the shuttle- like silicates due to heating in the process of welding simulation. These silicates used to get a higher sulphur capacity, so MnS deposits might be observed on the periphery of the silicates. IFP was proved to be directly rooted in the [Mn] depleting zone which locates beside MnS deposits.

Jan 1, 1997

By Agnes Y. Lee

he U.S. Bureau of Mines developed a method to treat lead-contaminated soil and ebonite battery casing wastes to produce a nonhazardous material. The cleanup procedure involves wet screening to separate a minus 18-mesh soil fraction; removal of metal1ic lead, rocks, wood, etc. ; carbonation to change lead sulfate to acid-soluble lead carbonate; size reduction; acid leaching; and rinsing. The casing wastes undergo size reduction and washing to remove the lead sulfate sludge before carbonation. Similarly, the minus 18-mesh soil is carbonated, then acid leached and rinsed. In leaching, fluosilicic acid (H SiF,) and hydrogen peroxide (H20,) are used to dissolve lead compounds. An electrowinning method is employed to strip lead from the lead-rich leachate. The acid content in the leachate is replenished with fresh H,SiF, acid prior to recycling. Treated casing wastes and soils pass the Toxicity Characteristic Leaching Procedure (TCLP) test and can be reclassified as nonhazardous materia1s. Based on this process, a conceptual pilot plant has been designed which will be demonstrated on wastes from two Superfund sites.

Jan 1, 1993

By A. Kar

A mathematical model is presented for pure titaqium deposition from titanium tetrabromide on a stainless-steel (SS 304) substrate. Five three-dimensional, transient, and nonlinear partial differential equations are used to account for the diffusion of various species inside the deposition chamber and the thermal decomposition of titanium tetrabromide, titanium dibromide, and titanium monobromide at the surface of the substrate in order to determine the thickness of the titanium film deposited on the substrate. The effects of various process parameters on the deposition and shape of titanium films are examined, and under certain conditions, the deposited titanium films are found to have volcanic profiles.

Jan 1, 1992

By Rejane Tubino Geyer

The volume of electric arc furnace (EAF) plus oxygen (BOF) slag produced yearly in the world is about 84 million ton. Because of this, the study of recycling processes as a way to solve the storage problem of these slags rise in importance. There are, however, some inconvenients on using this byproduct: lime, which takes part of the process of steel production, remains as a non-reactive raw product in the slag. Since lime reacts in presence of humidity, forming expansive compounds, slag use is strongly limited. There are some utilizations for the electric arc furnace and oxygen slag in the Civil Construction Industry, mainly as base, subbase and asphalt covering in highways. However, independently of the type of recycling, a period of "cure" of about six months is necessary. Because of this slow cure process this byproduct may turn non-competitive in some regions if compared, for example, with the natural aggregate. The objective of this work is to present the flowsheet of the slags production as a residue both at the electric and oxygen steel plants and, through a bibliographic review, to analize the possibilities and limiting factors for the use of steelmaking slags in the Civil Construction Industry.

Jan 1, 1996

By Yong Kuk Park

The horizontal cold chamber die casting process can produce a wide range of near-net shape, non-ferrous castings with small dimensional variation, excellent surface finish and very complex geometries. However, top quality die castings can be achieved only when optimal performance of the cold chamber and plunger is maintained during the molten metal injection phase of the process. Cold chambers (shot sleeves) are known to deteriorate fast and sometimes fail catastrophically because of poor design. Catastrophic fracture and wear due to deformation are leading causes to degrade quality, increase downtime and thereby decrease productivity and profitability. Therefore, a systematic approach to minimize irregular and adverse conditions which prevent an intended injection profile, is highly desirable. To eliminate them, design criteria for shot sleeves were developed using analytical tools and available experimental data. The correlation between design and mechanical failures of shot sleeves was shown by the data obtained from the die casting industry. Also, the relationship between die casting process parameters and deterioration/ failure mechanisms were carefully evaluated.

Jan 1, 1996

By George Oprea, Tom Troczynski, Joe A. Rigby, Waiman Lo

The refractory lining of the tuyere line in Peirce Smith converters have usually much shorter life in service than the rest of the lining, above or below it. There are already recognized chemical, thermal and mechanical factors which contribute to the wear of the lining. Our study presents the experimental results on microstructural changes occurring on these tuyere line bricks in a nickelcopper converter. The experimental bricks, after use at the tuyere line, were investigated using SEM/EDS and XRD techniques, to identify the mineralogical changes due to interactions with the nickel-copper matte or fayalite type slag at the process temperatures. The microstructural changes were correlated with physical and mechanical properties of the brick before and after use and a wear mechanism was suggested. Although the matte does not theoretically react with the mineralogical components of the brick, a partial oxidation of the Ni-Cu sulphides was identified using a line analysis by SEM/EDS in the densified layer at the hot face, which allows for mineralogical changes at the matte-refractory interfaces, with a high probability of microcrack formation due to the thermal cycling during use. These microcracks were also identified to open through inter-granular fractures parallel to the hot face, which appeared to be the main cause of lost lining during use. The reactions between the fayalite slag and refractory brick could eventually play a role in chemical dissolution of the brick only in the superficial layer at the hot face, as no slag components were identified deep into the brick.

Jan 1, 2009

By Jun Sugiyama, Hiroyuki Sano, Toshiharu Fujisawa, Hideki Takeuchi, Chikabiuni Yamauchi

"The solid .state electrotransport (SSE) is one of the most promising methods for the elimination of gaseous impurities from chemically active metals, such as rare earth metals. . In the present work, the SSE process was applied for the oxygen removal from praseodymium. The SSE factors, such as effective valence, were measured under the various temperatures, electric field intensities and initial oxygen contents, and the effects of those conditions on the SSE process were discussed. Furthermore, the solubility of oxygen in .solid praseodyillium was also measured·, by using the SSE method and metal-oxide equilibrium method.IntroductionWhen a direct current is passed through a solid alloy, not only electrons but also solute atoms are transported as charge carriers toward the anode or cathode. This phenomenon is referred to as an electrotransport or electromigration. The solid state electrotransport (SSE) is the application technique, based on this principle, to the pUrification of the solid metallic materials.Rare earth metals are used for various functional materials, such as magnetic, optical or electronic materials, therefore their high purity metals are required [l ,2]. However, rare earth metals are chemically active and have a strong affinity with gaseous elements (e.g. oxygen, nitrogen, hydrogen and carbon). In many cases, eliminating operations of gaseous elements have not been always made commercially, because these impurity elements could not be eliminated by usual treatments applied to the purification of ·common metals. As an alternative method, authors have proposed the· application of the SSE process to the elimination of gaseous impurities from rare earth metals. Investigations have been carried out on the yttrium-oxygen and neodymium-oxygen systems and the results were already reported[3,4]."

Jan 1, 2000

By Qingyu Deng, Shiwei Ma, Wang Hua, Guibao Qiu

"The flow properties of the blast furnace slag bearing high TiO2 at high temperature like the viscocity may change a lot due to the formation of the carbonitride inside, causing serious problems on the separation between the metal and the slag. Therefore, the critical condition of the formation of Ti(C,N) in blast furnace is vital importance for the ironmaking process with iron ore bearing titania. In this study, the formation of Ti(C,N) in blast furnace and the influences of various factors on the Ti(C,N) formation are investigated by FactSage. It is found that the mass of Ti(C,N) would reach the maximum at 1480 oC, and the product is mainly TiN below 1620 oC, while it is mainly TiC above 1620oC. The order of the factors by the importance from strong to weak was: temperature, the content of TiO2 in slag, basicity of slag, the content of MgO and Al2O3.IntroductionThe titanium dioxide (TiO2) in iron ore bearing titania will be partly reduced by carbon to titanium carbonitride (Ti(C,N)) in blast furnace, causing serious problems on the separation between the metal and the slag because of the change of flow property. Therefore, the critical condition of the formation of Ti(C,N) in blast furnace is vital importance for the ironmaking process, especially for the smelting of iron ore bearing titania. Extensive experimental data in regard to the formation of Ti(C,N) has been reported in numerous papers[1-6]. However, only some discrete data can be obtained by experiment, and it is difficult to detect the mass of Ti(C,N) in slag. In addition, the experiment is difficult to be proceeded when the temperature is above 1600oC. Therefore, it is very difficult to make clear the critical condition of the formation of Ti(C,N) by experiment."

Jan 1, 2012

By M. Potesser

One of the main targets in the automotive mass industry and supplying industry is the weight reduction of the vehicle for decrease of the fuel consumption. For that reason combinations of different kinds of materials and connections of, for example, steel and aluminium are developed or are already successfully field-tested. A determining factor concerning the quality assessment of the welded joint during hybrid welding is the characterization of the intermetallic Fe-Al layer regarding strength, hardness, morphology and mainly the different phases in which Fe occurs together with the Aluminum (FeAl, Fe2Al5, FeAl3.). A combination of conventional light microscopy, SEM - EDX - analysis, the usage of an atomic force microscope including a Nanoindenter and theoretical thermodynamic calculations turned out to be highly effective. Based on the attained results, the constitution of the intermetallic FeAl layer, influenced by silicon, manganese and zinc, can be predicted.

Jan 1, 2006

By Jun Lu, Min Chen, Wei-jian Su, Jian-zhong Luo, Yu-tao Lei

"In the case of treating phosphatizing wastewater containing zinc, zinc had an impact on the solution chemistry, especially on pH. Fe2(SO4)3 and CaCl2 were used as precipitators to remove phosphate from zincic phosphatizing wastewater and the optimum pH was investigated. Zinc ion had a significant effect on the optimum pH. The optimum pH ranges were 12.10(inlet concentration of 15.67mg/L, outlet concentration of 9.53mg/L), 3.04-5.50(inlet concentration of 11.97mg/L, outlet concentration of 0.44-0.26mg/L), and more than 10.72(inlet concentration of 12.24mg/L, outlet concentration of less than 0.47mg/L) under the conditions without precipitator, with Fe2(SO4)3 and with CaCl2 respectively.Introduction Phosphate coating is commonly used for protective coating of machine elements. Including oil removal by caustic washing, rust removal by acid washing, phosphatization and inactivation, the phosphatization process produces wastewater containing inorganic salt of high concentration, especially the phosphate, beyond the environmental standards and polluting environment seriously. What’s more, the wastewater from zincic phosphatizing technology also contains another pollutant, zinc. At present, Chemical Precipitation (CP) and Biological Nutrient Removal (BNR) are two of most common technologies of phosphate removal. BNR, such as A/O, A2/O and UCT technology, is suited for wastewater containing organ phosphorus of low concentration and CP for wastewater with phosphate of high concentration [1]. Researches on CP treating wastewater containing phosphate of high concentration, mainly focus on adding quantity of precipitators[2-5] and coagulants[2-4] and the choice of technologies[3-9]."

Jan 1, 2008

By R. Tunold, Y. J. Zhang

"The cathodic kinetics of aluminum deposition from aluminum chloridealkali chloride melts was studied by use of electro-cnemical transient techniques at 700 °C. Aluminum deposited as an insoluble product on a glassy carbon electrode and as a partly soluble product on a tungsten electrode. The deposition was found to be a simple diffusion controlled process involving the exchange of three electrons. The diffusion coefficient of aluminum chloride was calculated - 4.sx10-s cm2 ·S-I in AlCl3 -NaCl-LiCl melts and 2.6x10-s cm2 ·S-' in AlCl3 -NaCl-KCl melts. For AlCl3 -NaCl-CsCl system the diffusion coefficient exhibited some uncertainty due to nucleation. The determined rate constant of aluminum deposition reaction was on the order of 10-' -10-2 cm'S:' Constant potential electrolysis was carried out. TiB2 was well wetted by aluminum. The species of melts penetrated into graphite and glassy carbon but not into tungsten. The diffusion coefficient of species in glassy carbon was evaluated.IntroductionAluminum chloride electrolysis is attractive for its power saving of 30%. Different process to circumvent the conventional chlorization to obtain aluminum chloride economically, such as directly chlorizating mixture of Al~03 and C in a cell with A-shaped laminated bipolar electrodes by rising chlorine (1), or by use of a composite anode (2), will promote the electrolysis technology to be realized industrially. With the appearance of the Alcoa process periodically there are studies on the kinetics of aluminum deposition. Some discrepancies seem to exist on the mechanism of aluminum deposition. Borne studies (3,4,5) showed that the deposition of aluminum was hindered by diffusion process in the melts. M.Gabco et a1. (6) claimed a preceding dissociation of a complex being the rate controlled step. This paper presents our results on the mechanism of aluminum deposition from the study by use of transient techniques and some results from constant potential electrolysis."

Jan 1, 1988

By Richard P. Roberts

This paper will discuss the methods for the cooling of aluminum melting furnace? dross .and their impact on the environment. Also discussed will be a case history of an AROS Dross Processor installation, which is designed to maximize the recovery of metal content of the dross in a manner which is not only environmentally cleaner, but which also prepares the output in such a way as to facilitate downstream processes. Handling of the discharged material will be discussed in regards to the recycling of the preserved metal content and deposition of the unusable-materials.

Jan 1, 1992

By Yuanbo Zhang

Zinc leach residues produced by hydrometallurgical zinc plants contain many valuable elements (zinc, iron, lead, gallium, indium silver, etc), while they have not been utilized effectively hitherto. In this paper, a new process of flotation-reduction roasting-magnetic separation to recover these valuable elements from zinc leach residues is developed on a basis of mineralogy investigations of them. The results show that silver concentrate with grade of 4321.6 g/t and recovery of 80.69% have been obtained, using 1750 g/t Na2S as conditioner, 750 g/t ammonium dibutyl dithiophosphate and SN-9 (assistant collector) as combined collector and 100 g/t terpenic oil as frother, if zinc leach residues with 523 g/t silver are floated at pH = 5.0. When the flotation tailings are subjected to reduction roasting at 1100? for 2 h, the volatilizations of zinc, lead and indium are over 96%. After roasted products are treated by wet-grinding and magnetic separation, the grade of gallium and gallium in the concentrates achieved respectively reaches 1805 g/t and 1536g/t, and the recovery of them is high to 94.67% and 93.20%, respectively.

Jan 1, 2006

By Hans Jürgen Maier, Hans-Bernward Besserer, Gregory Gerstein, Florian Nürnberger

The formation and development of voids in both the single-phase ferritic steel DC04 and the dual-phase ferritic-martensitic steel DP600 are discussed. Various mechanisms and kinetics of void formation are considered regarding the influence of dislocation glide, precipitates and other parameters. Different characteristic locations in the microstructure are investigated at which strain concentrations during plastic deformation can occur and cause the formation of voids and microcracks. For the specimen preparation ion slope cutting is applied. Voids and cracks revealing ductile damage are analyzed by Scanning Electron Microscopy (SEM). Stress concentrations in consequence of plastic deformation could be shown by extinction contours on images recorded by Transmission Electron Microscopy (TEM).

Jan 1, 2015

By E. V. Redin, B. A. Dubrovsky, E. V. Knyazev, A. I. Starikov

"Ti-V magnetite is one of the most abundant composite ore resources in the world. This ore cannot be fully processed via blast furnace technology because of high content of Ti02. According to the investigations carried out in the USA and Japan ITmk3 RHF (Rotary Hearth Furnace) technology is a breakthrough in Ironmaking. Reduction, melting and slag removal can be achieved in just 10 min. The main objective of the investigation is to establish optimum operation conditions for the production of iron nuggets from Ti-V magnetite ore via the ITmk3 by means of the lab scale testing. Samples of ore from the Maly Kuybas deposit (Southern Ural), carbon reductant and fluxes were chemically analyzed. Green pellets were processed via a lab chamber furnace to simulate RHF conditions. The nuggets and slag were chemically analyzed. This preliminary test work provides valuable information which may be used for large-scale testing in a commercially sized RHF.IntroductionThe ITmk3 process upon which this paper focuses was developed by Kobe Steel in its research facilities [l]. After pilot testing at Kobe Steel's Kakogava Works in 1999-2004 the pilot demonstration plant was built and operations were successfully carried out by Mesabi Nugget joint venture in 2002-2004. Steel Dynamics put into operation the commercial plant at the Mesabi Nugget site in Hoyt Lakes (Minnesota) in 2010. Results were consistent with nugget characteristics confirming ITmk3' s flexibility with respect to raw material inputs. At the same time, no research in the field of nugget from the Ti-V magnetite bearing ore with high content of Ti02 and Alz03 has been done. It is well known, if a lot of Ti02 and Alz03 enter the blast furnace, slag becomes viscous. The viscous slag is obstacle for stable operation of the blast furnace. Besides, high content of Alz03 raises the melting temperature of gangue minerals disturbing the coalescence of reduced iron to the nuggets."

Jan 1, 2013

By R. B. Nourse

The depressed market for Ferrochrome worldwide has forced most producers in this industry to scale down production. Inevitably, many furnaces have been mothballed for prolonged periods, awaiting an upturn in the Ferrochrome market. In contrast, the Platinum industry is experiencing relative stability combined with good prices and they have been looking for cash cows to take advantage of these market conditions. It is, therefore, rather convenient that Platinum and Ferrochrome producers are virtually neighbours in the Bushveld complex of South Afiica, since there is an abundance of spare furnace capacity around (albeit for Ferrochrome). Against this backdrop, Pyromet Technologies (Pty) Ltd, who are currently designing a slag cleaning furnace for Anglo Platinum, was requested to perform pilot scale testwork on a 200kW furnace, in order to establish the suitability to process platinum concentrate and converter slag in a furnace designed for Ferrochrome. This paper provides an overview of the configuration, test conditions, operation and results achieved during the testwork. It also discusses the critical issues, such as refractory consumption, copper cooling and electrical parameters that need to be addressed when converting a Ferrochrome Smelter into a Sulphide Smelter.

Jan 1, 2002

By Feng Liu

A thermal upgrading process by which nickel value can be concentrated in a ferronickel alloy is a possible alternative to treat Sudbury pyrrhotite (Po) tailings with nickel content of 0.5–1.5 wt%. The basis of this process is precipitation of Ni from Po at high temperature once Fe/S ratio in the iron-deficient Po is shifted towards stoichiometric or near stoichiometric FeS (troilite) either by the addition of iron and/or the removal of sulfur. For the iron addition route, the reaction between elemental iron and nickeliferous pyrrhotite to produce ferronickel alloy and Ni-depleted iron sulfide phase plays a critical rule. In this paper, the formation mechanism of ferronickel alloy was investigated using the diffusion couple technique to better understand the nickel diffusion behavior in the iron and sulfide phases.