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By Guo Chen, Jin Chen, Jinhui Peng

In this study, the influences of the green evaluation variables on the characterization of microwave shaft furnaces were systematically investigated. These variables include: resource consumption, environment impact, production cost, processing time and quality of microwave shaft furnaces. A greenness evaluation index, evaluation system and evaluation model of microwave shaft furnaces were established. The analytic hierarchy process and fuzzy comprehensive evaluation were applied to the evaluation process. Resource consumption and environment impact had a statistically significant effect on the green evaluation of microwave shaft furnaces. The results indicated that green evaluation techniques can be applied effectively and efficiently to the process manufacturing of microwave shaft furnaces.

Jan 1, 2015

By Cui Wang, Kexin Jiao, Qiuye Cai, Jianliang Zhang

Prolonging the campaign life of the blast furnace has been an important task for iron makers, and it has been studied for decades. Adding titanium-bearing materials is a generally agreed and effective technique to protect the blast furnace hearth. Titanium from titania additions in the burden or tuyere injection react with carbon and nitrogen and form scaffolds on the hearth surface to protect the hearth from subsequent erosion. In this article, the progress on blast furnace hearth protection of titania additions in Chinese steel companies and research institutions is investigated, and the difficulties in the operation and production, such as little effect after adding titaniumbearing materials and the property deterioration of liquid iron and slags, are analyzed. The future research for protection in Chinese blast furnace is proposed, and a comprehensive process which combines protection of titanium bearing materials with reasonable thermal balance and slagmaking regimes should be established.

Jan 1, 2015

By Zhijing Zhang

Sodium borosilicate is the basic composition of coating materials, Vycor and Pyrex glasses. In the present study, viscosities of Na2O-Si02-B2O3 ternary melts were measured under various compositions and temperatures. Experiments were carried out using rotary viscometer and graphite components. Our experimental results were compared with those in literature. Based on present experimental results, the previous structure based viscosity model was modified. The predicted viscosity results are in excellent agreement with the present experimental data in the temperature range with molten state samples. The fitting ranges of the model cover the composition of XB2O3 from 0.1 to 0.6 combined with xSio2 / xNa2O = 0.5, 1,2 and 5 respectively.

Jan 1, 1998

By V. Ramachandran

In view of the increasing environmental regulations that have been promulgated in the last 30 years, non-ferrous smelters and refineries have learnt to handle effectively the process waste streams that need to be bled from the system for impurities' control. The cations of concern are copper, lead, zinc, cadmium, mercury, thallium, nickel, silver, sodium and potassium. Anionic species of arsenic and selenium also need to be addressed, Sulfates and chlorides-not a major concern at present-have come under scrutiny in the recent past. The current paper reviews several treatment options with reference to a) types of waste streams processed b)process chemistry c )discharge options and recovery of treated water and d) sludge disposal. The long term goal of any smelter and/or refinery should be to achieve zero liquid discharge from the plant. Methods to obtain zero discharge are discussed.

Jan 1, 2003

By A. E. Clark

Rare earth compounds are widely known as possessing many extraordinary magnetic properties. In this paper, we focus on the huge magnetically induced displacements (magnetostrictions) which characterize the compounds of terbium with iron (Terfenol). Materials prepared commercially by both free-standing-zone (FSZ) and modified Bridgman (MB) techniques have now become available in large sizes and shapes. Prior to the development of the Terfenol alloys, it was possible to achieve giant magnetostrictions only at cryogenic temperatures. In the cubic Laves phase TbFe2 compound, saturation strains exceed 3000 x 10-6 at room temperature and above. Large magnetization 'jumps' can occur, causing huge spontaneous magnetostrictions with small triggering magnetic fields.

Jan 1, 1992

By Huaming Yang

The vanadium-doped SnO2 nanoparticle was synthesized by the co-precipitation reaction and subsequent calcination from the vanadium(III) chloride and tin(IV) chloride. The crystal size, pore size distribution, micrograph and properties of the nanocrystalline powders were examined by differential thermal analysis (DTA). thermogravimetric analysis (TGA). X-ray diffraction (XRD), desorption isotherm (Barrett-Joyner-Halenda method) and transmission electron microscopy (TEM). Thermal treatment of the precipitate powder at 600'C led to the formation of crystal0nmincrystal size. Most of the pores in the narmparticle are about 5~15nm in diameter. Effect of doped vanadium on the crystal size of the nanoparticle was discussed.

Jan 1, 2003

By G. H. Khoe

Although some hydrometallurgical process liquors contain significant amounts of ferrous and arsenate ions, no reliable thermochemical data for the aqueous complexes and the solubility of the ferrous arsenate precipitate are available. The complexation of iron(11) with arsenate has been investigated using the potentiomemc titration method. The results indicated that virtually no complexation of iron(@ with arsenate has been observed. This is in contrast to the significant complexing reported for iron(1n) with arsenate. The solubility product of the precipitate was calculated using the concentrations of appropriate arsenate species pertaining to the observed precipitation pH's. The fit of the observed precipitation points on the solubility curve of the computed stability diagram was used to assess the appropriateness of the equilibrium model.

Jan 1, 1991

By A. Valenzuela

During the last years, Chile has been the largest copper producer, either as concentrates or cathodes. Copper obtained via pyrometallurgy is produced by seven smelters, which have carried out modernization plans to increase smelting capacity or to achieve environmental regulations established in the Chilean legislation. Thus, the present work updates technological innovations in smelters, environmental regulations and presents solutions for S02 handling, particulate matter and arsenic. Also, the authors emphasize the important role of CODELCO Chile, the most important state-owned copper company, in developing technologies such as El Teniente Converter and El Teniente Slag Cleaning Furnace.

Jan 1, 2003

By R. A. Masumura, C. S. Pande, D. Agassi

"Grain size has a different effects on the critical current density (Jc) of high and low transition temperature (Tc) superconductors. In high Tc superconductors, the critical current density Jc across grain boundaries depends sensitively on the misorientation 8. It was pointed out by Pande that this dependence is directly related to dislocation structure of the grain boundaries i.e., it is due to dislocation cores and stresses. These ideas are developed further in this paper leading to a relation between Jc and 8. The analytical result is compared with the experimental results on bicrystals and used to explain the difference in behavior between high and low Tc superconductors.IntroductionThe grain size distribution and its evolution with time and temperature is important in determining the properties of high and low transition temperature (T c) superconductors. The distribution is a convenient function to characterize the processing of a high Tc material during sintering. For example, it is known that the maximum density of ceramic materials is obtained when the grain growth is reduced but grain boundaries are still mobile. For practical superconductors, the processing parameters are selected to achieve optimum properties: highest possible T c and maximum critical current (Jc). In terms of an average grain size, the requirements for optimum T c and Jc are sometime in conflict. In A15 type superconductors and even in NbTi, larger Jc have been measured in smaller rather than larger grain sized material. Conversely, in a high Tc materials like YBa2Cu307, higher Jc have been found in larger grain sized or single crystal specimens.Extended defects such as grain boundaries in low T c superconductors can be effective pinning agents for magnetic flux lines, thereby increasing the transport critical current density of these materials [1]. On the other hand, the transport critical currents in polycrystals of high Tc superconductors such as YBa2Cu307 is found to be relatively small (much smaller than those in single crystals of the same material) [2]. It is now known that grain boundaries in high Tc polycrystals can in many cases form ""weak links"" reducing the critical current density across them. This phenomenon can be studied more precisely by experiments on bicrystals, where there is only one grain boundary. It is found that the critical current density is quite sensitive to the misorientation angle of the bicrystal [3,4]. Although the original experiments were conducted on YBa2Cu307, other Tc superconductors have been shown to give the same result [5]."

Jan 1, 1994

By Julian Szekely

A review is given of the current metals processing operations, where electromagnetic forces play an important part in affecting the performance of the system. These include arc furnaces, plasmas, the Hall Cell, electromagnetic stirring and others. These considerations will be extended to discuss what new frontiers may be breached by the intelligent application of electromagnetic phenomena. The topics discussed will include magnetic flow control, levitation melting and cold crucible melting and refining.

Jan 1, 1988

By Huaming Yang

The vanadium-doped SnO2 nanoparticle was synthesized by the co-precipitation reaction and subsequent calcination from the vanadium(III) chloride and tin(IV) chloride. The crystal size, pore size distribution, micrograph and properties of the nanocrystalline powders were examined by differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction (XRD), desorption isotherm (Barrett-Joyner-Halenda method) and transmission electron microscopy(TEM). Thermal treatment of the precipitate powder at 600°C led to the formation of V -SnO2 nanoparticle of -10mm in crystal size. Most of the pores in the nanoparticle are about 5~15nm in diameter. Effect of doped vanadium on the crystal size of the nanopartic1e was discussed.

Jan 1, 2003

By M. Nishikawa

The Hachinohe Smelter employs the Imperial Smelting Furnace (ISF) for production of zinc and lead and handles a large number of concentrates and recycled materials. In recent years, recycled materials such as zinc-bearing materials, lead sludge and Waelz oxide have provided up to 30% of the feed materials at the plant. To allow for a satisfactory operation using such a wide range of recycled materials, the Hot Briquetting Plant was built in 1986 and started its operation in January 1987. In April 1988 the zinc production capacity of the ISP was increased from 81,000 to 101,000 tonnes per year. The additional production in the ISP has been attributed to the utilization of the hot briquetting process. This paper describes the various facts of the smelter, concentrating on hot briquetting operations and treatment of hot briquettes in the ISF.

Jan 1, 1991

By James T. Staley

Quenching and aging are critical processing steps used to produce precipitation hardenable aluminum alloy products. This work describes personal computer programs that employ models to predict certain properties after quenching and aging and graphically display them. One of the programs allows the user to predict the attainable strength and toughness of aluminum alloy products after an arbitrary quench. Another program simulates the changes in strength and electrical conductivity occurring during second-step aging alloy 7050-T7X products as a function of thickness, furnace temperature set point, and furnace characteristics.

Jan 1, 1993

By R. M. G. S. Berezowsky

Treatment of Hudson Bay Mining and Smelting Co. Ltd. (HBM&S) zinc concentrate in the Sherritt zinc pressure leach process produces a residue containing elemental sulphur, residual sulphides, precipitated iron species, si1ver and gold. Flotation of the residue recovers most of the elemental sulphur and residual sulphides to the concentrate, leaving iron oxides and bask sulphates in the tailings. The tailings also contain most of the sflver and some gold. Direct cyantde leaching of the oxide tailings (220 g/t Ag, 1.4 g/t Au) was capable of leaching most of the gold, but only a minor portion of the silver. This paper reports testwork, conducted by Sherritt on behalf of HBM&S, to define a process for a high recovery of the precious metals from the oxide tailings. A si1ver enhancement treatment, consisting basically of digestion of the residue with lime at 90°C to render the silver amenable to enhanced recovery by subsequent cyanidation, was selected as the most promising approach. Batch silver enhancement and cyanidation tests showed that treatment of the oxide residue with 80 kg/t CaO at 90°C for 1 to 2 h increased the silver extractability in subsequent cyanidation from <20% to 96%. A 96 h continuous miniplant test (1 kg/h solids feed rate), of a circuit including a silver enhancement treatment step followed by conventional cyanidation and carbon in pulp silver and gold recovery, confirmed metal recoveries to the carbon of 90% Au and 96% Ag. Reagent consumption rates were 1ess than 100 ?kg/t CaO and 5 kg/t NaCN.

Jan 1, 1990

By Heimo Thalhammer

During the refining of lead, copper or other metals the furnaces used in the process · often produce waste gases. This paper illustrates how these waste gases can be successfully treated and destroyed by CTP 2-bed or multi-bed compact systems, modified for the additional reduction of dioxins and furans. The CTP regenerative thermal oxidizer also destroys voes (organic compounds and odours) using ceramic blocks as a heat exchanging media. The raw gas is forced through the ceramic beds where it is heated up to the oxidation temperature level. The voes, dioxins and furans are destroyed in the combustion chamber, subsequently generating water, eo2 and heat. The hot purified gas heats up a second ceramic bed, which is used to preheat the raw gas after the valves have been switched. This process does not produce any secondary waste such as contaminated water, polluted air or any other products that have to be disposed of.

Jan 1, 2000

By R. P. King

The linear intercept distributions provide unambiguous and accurate characterizations of the texture of mineralogical materials. The relation between the measured linear intercept distributions and the spatial correlation function is shown to be given by: in the Laplace Transform domain. The linear intercept distributions of the two phases in a low- grade chromite-serpentinite ore were measured. and the spatial correlation functions for both phases were evaluated using the above relation. The correlation functions are the primary relations for integral geometric models of mineralogical texture and this work demonstrates the relation between the 10 stereological model and the 3D integral geometry model for mineral liberation.

Jan 1, 1991

By Yongfeng Jia

Lime neutralization and co-precipitation of As(V) with iron(III) is the most widely used and most economical method for the removal of arsenic from mineral processing solutions and effluents. However, the arsenate fixation mechanism in the coprecipitated solids is not fully understood. It was suggested by various researchers to be a ferrihydrite precipitation process during which arsenate is removed by adsorption on ferrihydrite. In this study, XRD, EXAFS and microprobe were employed for the speciation of arsenic and the effect of various factors on arsenic solubility was also investigated. The results indicate that coprecipitation is a more complicated process than simple adsorption resulting in lower arsenic solubilities. Poorly crystalline ferric arsenate was observed for the first time to be present in the coprecipitated solids. In case of lime as base, there exists some type of Ca-Fe-arsenate association. A general term ?coprecipitate? is suggested to describe the precipitated arsenic-bearing solids instead of those widely used specific terms ?arsenical ferrihydrite? or ?arsenic-bearing ferrihydrite?.

Jan 1, 2005

By F. Qian

An impinging gas jet on a liquid surface is found in many industrial process systems such as electric arc furnace, welding, steel-making operation and others. Fundamental understanding of the interaction of a gas jet on a liquid pool can provide important insights into process behavior resulting in improved efficiency. A numerical model is developed for solving the flow fields of both impinging gas jet region and liquid pool below, in which the deformed interface shape is predicted simultaneously. Using curvilinear coordinates, the Navier-Stokes equations of each phase are solved separately through coupling of static pressure, shear stress and velocity at the interface. Several cases for jet distances and flowrates were investigated both numerically and experimentally with an air-water model. Favorable comparison of numerical results with experimental data confirms the validity of the present numerical approach. An existing phenomenological model for &apos;penetration depth&apos; prediction was extended for smaller 3et exit height to jet diameter&apos; ratios.

Jan 1, 1995

By Nobuhiro Kuriyama

Electrochemical activation behavior of an AB2-Laves-phase type hydrogen storage alloy, Zr0,9Ti0.lNi1.lCo0.1Mn0.6V0.2 was studied to make clear activation process of pellet-type metal hydride electrodes. An alkaline treatment of the electrodes with heated alkaline solution gave alloy surface enriched with nickel, and the treated electrode was more easily activated. The treated electrode desorbed more hydrogen during the first charge-discharge cycle, and was activated without induction period. A cross sectional view of the activated electrode showed finer pulverization of alloy particles than the annealed alloy, and impedance spectroscopy indicated larger surface area of the electrode using the as-cast alloy. Since the as-cast alloy contains inhomogeneities, multi-phase microstructure and stress in the particle, the finer pulverization of alloy particles with hydrogenation are considered to increase surface area in an earlier cycle in the case of the as-cast alloy, which leads larger reaction area and faster activation of the as-cast alloy electrode.

Jan 1, 2002

By H. H. Law

Large amounts of waste material in the form of flue dust are generated in the operation of copper smelter furnaces. As a result of increasingly stringent disposal, it has become important to develop methods for treating such metallurgical wastes to extract metals and convert them into salable products. A two-step closed-loop hydrometallurgical process, has been developed: (1) extraction with sulfuric acid removes about 90% of zinc and decreases the dust volume by 50%; (2) extraction with hydrochloric acid dissolves the lead and further decrease the dust volume by 75%. A process scheme for generating salable products is proposed.

Jan 1, 1992