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By A. J. Maselli, E. C. Cemak

Hartford Steel Technologies (HST) has a pyrometallurgical and hydrometaliurgical process capable of reclaiming valuable metals from a hazardous waste· stream such as EAF Dust. The HST Process effectively addresses the growing environmental concerns surrounding the increasing production of EAF Dust without producing any hazardous waste material as byproducts. Currently EAF Dust production levels are exceeding the 1,000,000 metric tons per year mark. The HST Process is designed to separate iron, zinc, lead, cadmium, copper, and silver metals using a two-phased process. The Pyrometallurgical side of the Process utilizes a Rotary Hearth Furnace to separate the iron metal from the remaining metals. These remaining metals are further separated, using a Hydrometallurgical Process, in a series of digestion tanks. The individual metals are then collected in saleable form.

Jan 1, 2000

By Marisa Di Sabatino, Michael Phan Knudson, Mari Juel, Eivind Øvrelid

"A p-type Czochralski silicon ingot doped with boron was characterized for resistivity, minority carrier lifetime, interstitial oxygen, and metallic impurities. Analyses show a peak in resistivity and a dip in lifetime both occur 5 cm from the top of the ingot crown. This peak in resistivity deviates from the expected trend based on Scheil's equation for boron distribution. High concentration of interstitial oxygen in this area suggests that other oxygen-related defects, such as thermal donors and precipitates, may also be present here, and the observed peak in resistivity and dip in lifetime could be attributed to such defects. The low lifetime of 15-30 µs at minority carrier density of 7.5 x 1014 cm-3 is likely due to copper contamination.IntroductionSolar energy resources vastly exceed all other alternative energy resources, ensuring that solar power must play a crucial role in the evolving energy market. The economic viability of solar power in competition with other energy resources depends upon finding efficient, cost-effective, reliable, and controlled methods for solar cell production. In this regard, minimizing waste (such as material with unsuitable electrical properties that hinder solar cell performance) is a vital component of making solar cell manufacturing cost-effective. Impurities affect electrical properties of solar cell silicon in different ways (i.e. [1, 2, 3, 4, 5, 6]). In this work we focus on the role of oxygen and metallic impurities. Understanding oxygen impurities in silicon is critical to solar cell development because oxygen has been attributed with influencing critical electrical properties including resistivity and minority carrier lifetime and thereby potentially hindering solar cell performance or rendering material unsuitable for solar cells.[1, 2] Furthermore, oxygen is a common impurity in the standard type of solar cell silicon, Czochralski (CZ) silicon, due to diffusion of oxygen from the silica crucible into the melt during crystallization. [7] This study investigates the effects oxygen impurities have on the electrical properties of p-type CZ silicon."

Jan 1, 2013

By Lei Zhang, Shining Chen, Lina Wang, Pu Liu, Benquan Fu, Jiannyang Hwang

The present status of wastewater advanced treatment and reuse in iron and steel enterprise is discussed, and the membrane technology used in wastewater advanced treatment and reuse from iron and steel enterprise was investigated. Its advantages, disadvantages and the development tendency were discussed and some advice and prospects of membrane technology for the reuse of wastewater treatment in iron and steel enterprise were pointed out.

Mar 1, 2017

By G. G. Richards

The zinc slag fuming process is used to recover zinc from molten iron-calcium silicate slags by treatment with pulverized coal and air. The rate of zinc fuming is controlled by the complex interaction of several kinetic factors including the rate of entrainment of coal in the slag, the extent of the coal-slag reaction and the rate of ferrous oxide oxidation to ferric oxide. This paper briefly outlines the mechanism of fuming and, on this basis, optimization of process parameters is discussed. Modelling analysis and recent industrial trials at Cominco show that coal entrainment in the slag, bath temperature, and bath depth are critical variables affecting process rate and efficiency. The first step in process optimization is to assess coal bypass of the bath. In general, changes which promote operation at a higher temperature, greater coal entrainment in the slag and extended residence time of the coal in the bath increase fuming performance. Coal entrainment is controlled by injection conditions whereas bath temperature is a function of coal combustion and ferrous oxide oxidation. Residence time of the coal is largely a function of bath depth. The implication of model predictions for continuous fuming is shown.

Jan 1, 1994

By Zhenglong Li

A process has been developed to recover titanium from a blast-furnace slag which contains about 20-25% Ti02 and 12% Fe. In this process. "hot" slag from the blast furnace is directed to a separate furnace where it is reheated with additives to form two simple slag phases: one is titanium enriched anosovite (Ti3O5) and the other is a titanium lean non-crystal glass phase. The modified slag is then processed by conventional beneficiation techniques to produce a marketable titanium concentrate and a usable slag material. This paper focus on separating anosovite from glass by electrostatic separation and froth flotation.

Jan 1, 1996

By Yong Li, Tao Jiang, Xiangxin Xue, He Yang

"In this paper, we describe the current status and research progress on the utilization of typical industrial solid wastes in China. We propose a creative method called “eco-utilizing wastes” with an aim of both integration and increment but without second-time waste and pollution, in terms of the characteristics of typical industrial solid wastes, such as titanium-bearing blast furnace slag, high-silicon iron tailing and boron-enriched slag as well as oil shale.Situation of Typical Industrial Solid Wastes in ChinaThough mineral resources in China are abundant, most of these are low grade ores. Moreover, the distribution of mineral resources is asymmetric, which causes the increase of cost and decrease of the economic benefit. Over-exploitation of mineral resources results in a large number of solid wastes. The accumulation of solid wastes not only means the waste of valuable resources, but also causes environment deterioration. There exist some problems in the current practice of the disposal of industrial solid waste, such as only emphasizing the final results and causing new pollution and waste [1]. So the research and development of a high value-added method has a high practical relevance to our nation. Based on the present status and research progress of industrial solid wastes in China, a creative new idea and method for eco-utilization of solid wastes is proposed in this paper."

Jan 1, 2012

By A. S. Usmani

The flow associated with the pouring of molten metal into moulds has been modelled on the basis of certain simplifying assumptions. A finite element based Navier-Stokes equation solver has been used to analyse the flow. The velocities obtained from the Navier-Stokes equation solver are used to advect a pseudo-concentration function for modelling the fluid front. A simple problem with a known analytical solution is solved first to test the model. Subsequently, several more examples with varied geometrical configurations are modelled, including one with curved flow boundaries.

Jan 1, 1992

By Chengyi Ding, Xuewei Lv, Changyang Ji, Rende Zhang, Xiangwei Zheng

Inexpensive and high-quality sinter has an extraordinary position in iron making, and there are many factors influencing the sintering. This research takes the basicity and coal dosage as research subjects to do the experiments based on cost analysis with sinter pot experiment system. Linear program is taken to make the schemes of ore blending. During the experiments of changing basicity from 1.6 to 2.3, the properties and microstructures of the sinter are studied. It comes to a conclusion that increasing the basicity is beneficial to sinter quality but leads to higher cost. To further ascertain the cost of sinter and the potential of saving coke, the work of improving coal dosage is taken on the basis of experiments of changing basicity. Through analyzing the results, a formula (Y=1849+261.1R-130.6C) is proposed which indicates the relation among the cost, basicity and fixed carbon content. And it works well for actual production.

Jan 1, 2015

By Miao Tian

Large quantities of copper complex resources are produced globally and urgent to be cleanly processed. This article presents a thermodynamic analysis of mixed smelting process including low-grade polymetallic copper sulfide concentrates, high copper content sulfide concentrates, metallurgical by-products (copper removal slag from lead metallurgy), and copper powder from electronic waste. A top blown smelting reactor to simulate mixed smelting process is developed using a metallurgical process simulator, METSIM. Reactor parameters, heat loss and phase distributions are estimated from actual plant data. The proper proportion between complicated primary and secondary copper resources is determined by analyzing the influence of the feed rates of various resources, oxygen, silica flux and revert on the smelting performance. Autogenous smelting process is built by optimized matching materials of copper complex resources, in terms of the reactor temperature, copper content in matte and slag, and the percentage of magnetite in slag.

By L. M. . Chia

The successful treatment of waste materials to recover metals with acceptable purity is often hampered by the presence of undesirable impurities. The problem is further complicated by the need to insure that any residues or solutions generated are environmentally acceptable. Hydrometallurgical processes involving leaching- solvent extraction-electrowinning offer some attractive features which address many of these problems. However, in certain instances trace impurities that contaminate the organics are difficult to chemically strip and interfere with the overall process efficiency. A new processing scheme has been developed which appears to provide some attractive alternatives for impurity removal from organics. It has been shown that many ionic impurities can be electrochemically removed from the organic by spontaneous direct reduction using solid metals. A variety of metal ion impurities have been removed from selected common organic extractants such as D2EHPA and TBP using different metals as the reducing agents. The results and probable mechanisms involved in the reactions are discussed.

Jan 1, 1994

By Patrik Fredriksson

Thermodynamic data concerning FeO-containing slags is of importance in ladle refining of steel. With a view to generate a set of reliable and self-consistent thermodynamic data for these slags, experimental determination of the activities of FeO in binary and ternary slags was carried out using the gas equilibration method involving CO-C02-Ar gas mixtures at steelmaking temperatures. The slag samples in Pt crucibles were quenched after the equilibration and subjected to chemical analysis. The thermodynamic activities of "FeO" in the slags were calculated from the experimental data. The results are incorporated into a thermodynamic description of silicate melts in the present laboratory. The model is based on a Temkin-Lumsden approach and is able to compute the thermodynamics of higher order systems from the lower order ones.

Jan 1, 2003

By Linfeng Zhou, Rong Sun, Guanghui Li, Zhiwei Peng, Tao Jiang

Dust, or airborne particulate matter, from metal smelting can be either mechanically or thermally generated and it negatively affects the indoor air quality as well as the fugitive emissions from the plant. The thermally generated dust is often referred to as fume and it is typically generated whenever liquid metal comes into contact with air. For practical reasons, such as vehicle access, etc. it is often difficult to collect 100% of the fume. It is therefore highly desirable to develop processes and optimize operational procedures so that fuming can be kept to a minimum. In this series of experiments, the mechanism of active oxidation and fume formation from liquid silicomanganese under an impinging air jet in the temperature range 1400-1600°C has been explored. Characteristic properties of the fume have been established; particle diameter, shape, size distribution, and elemental composition are reported. The oxidation process is described in terms of vaporization, oxidation and agglomeration. In the boundary layer, two competing mechanisms seem to be operative in parallel: a direct oxidation of Mn vapor, and a two-step oxidation of silicon. The thermodynamic and kinetic conditions governing the two mechanisms are discussed.

Jan 1, 2016

By Neng-Wen Yu, Shau-Jun Zhu, Ji-He Wei

The desulfurization process by powder injection and blowing in the RH refining of molten steel and its mechanism have been considered and analyzed. Based on the two-resistance mass transfer theory and the mass balance of sulfur in the system, a kinetic model for the process has been developed. The related parameters of the model, including the mass transfer coefficients and the effective amount of powder in the molten steel being treated for desulfurization, have been more reasonably determined. Modeling and predictions of the process of injecting and blowing the lime-based powder flux under assumed operating modes with the different initial contents of sulfur and amounts of powder injected and blown in a RH degasser of 300 t capacity have been carried out using the model. The relevant circulation rate of the liquid steel and the powder injection and blowing rate were taken to be 100 t/min and 150 kg/min, respectively. The initial contents of sulfur in the liquid steel to be treated and the amounts of powder injection and blowing were respectively assumed to be 0.007, 0.006, 0.005, 0.004, 0.003, 0.002 mass-% and 10, 8, 6, 5, 4, 3 kg/t-steel. The total treatment time for desulfurization under each mode was set up at 24 min, equivalent to eight circulation cycles of the liquid steel to be treated. The results indicated that the predictions made with this model are in good agreement with some data of the industrial experiments and practice. Injecting and blowing the lime-based powder flux with the composition of 85 mass-% lime (CaO) + 15 mass-% fluorspar (CaF2) of 3-5 kg/t-steel, it is possible to decrease the sulfur content in the molten steel to ultralow level below (5-10)x10·4 mass-% from (60-80)x 10·4 mass-%. The total treatment time needed will appropriately be 12-20 min. Intensifying the powder injection and blowing operation and increasing the circulation rate of the liquid steel may effectively' raise the rate of the process in RH refining. The model may be expected to offer some useful information and a reliable basis for determining the reasonable process parameters and help in optimizing the technology of desulfurization by powder injection and blowing in the RH refining of molten steel.

Jan 1, 2000

Laminated ceramics have received widely scientific and commercial attention because their properties, such as mechanical properties and electrical properties, can be tailored by adjusting the structure, thickness and composition of the different layers. For example, ferroelectric Bi4T13O12 (BIT) which has a positive temperature coefficient of dielectric constant (TE) can be used to modify the negative of typical microwave dielectric ceramic BaNd2Ti4O12(BMT). However, BaNd2Ti4O12/Bi4Ti3O12/BaNd1Ti4O12 (BNT/BIT/BNT) laminated ceramics could not be prepared by the general method because the optimal sintering temperature of BaNd2Ti4O12 ceramic (around 1350°C was much higher than that of Bi4Ti3O12 ceramic (around /1100°C). in this research, a new method of spark plasma sintering (SPS) combined with post-sintering was successfully proposed to prepare BNT/BIT/BNT laminated divided proposed to prepare ceramics. It was divided into three steps. In first step, the BaNd2Ti4O12 ceramics were prepared by conventional sintering method. In second mop, the calcined and pre-pressed Bi4Ti3O12 powders were sandwiched between BaNd2Ti1O12 ceramic pellets and spark plasma sintered at 900'C for 10min to synthesize BNT/BIT/BNT composite ceramics. In the last step, a post-sintering was employed to reoxidize the partially reduced BNT/BIT/BNT composite ceramics. The results of scanning electron microscopy (SEM) and electron probe mircoanalysis (EPMA) showed that BNT layer and BIT layer were well bonded and no significant interfacial infiltration between them was observed. The sandwiched BNT/B1T/BNT ceramic with 10.7% BIT in volume has a dielectric constant of 92.8, a low dielectric loss of 0.0068 and a small temperature coefficient of dielectric constant v/35 ppm/C at 1 MHz.

Jan 1, 2003

By Yong .. Jun Wu

Laminated ceramics have received widely scientific and commercial attention because their properties, such as mechanical properties and electrical properties, can be tailored by adjusting the structure, thickness and composition of the different layers. For example, ferroelectric Bi4Ti3O12 (BIT) which has a positive temperature coefficient of dielectric constant (,E) can be used to modify the negative tE of typical microwave dielectric ceramic BaNd2Ti4O12(BNT), However, BaNd2Ti4O12/Bi4TiO12/Bi4Ti3O12/BaNd2Ti4O12 (BNT/BIT/BNT) laminated ceramics could not be prepared by the general method because the optimal sintering temperature of BaNd2Ti4O12 ceramic (around 1350°C) was much higher than that of Bi4Ti3O12 ceramic (around 1100°C). In this research, a new method of spark plasma sintering (SPS) combined with post-sintering was successfully proposed to prepare BNT/BIT/BNT laminated ceramics. It was divided into three steps. In first step, the BaNd2Ti4O12 ceramics were prepared by conventional sintering method. In second step, the calcined and pre-pressed Bi4Ti3O12 powders were sandwiched between BaNd2Ti4O12 ceramic pellets and spark plasma sintered at 900°C for 10min to synthesize BNT/BIT/BNT composite ceramics. In the last step, a post-sintering was employed to reoxidize the partially reduced BNT/BIT/BNT composite ceramics. The results of scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) showed that BNT layer and BIT layer were well bonded and no significant interfacial infiltration between them was observed. The sandwiched BNT/BIT/BNT ceramic with 10.7% BIT in volume has a dielectric constant of 92.85, a low dielectric loss of 01068 and a small temperature coefficient of dielectric constant of 35 ppm/°C at MHz.

Jan 1, 2003

By Merete Tangstad, Ragnar Tronstad

Ferromanganese production in electrical furnaces is quite an old process. However, as the furnaces are getting bigger, the requirements of cost, yield, product quality, emissions and security are raised. With the increased expectations, the fundamental knowledge must follow. Within the last 25 years there has been a great effort both in the industry as well as the academic environment to push the limits of this process. This article will show some examples of improvements within fundamental data, reaction mechanisms and emissions over this time period.

Jan 1, 2014

By Pengfu Tan

NiModel, a thermodynamic model, database and computer program, has been developed to predict the distribution behavior of Ni, Cu, Co, Fe, S, O, As, Sb and Bi, and heat balance in the nickel pyrometallurgical processes such as Outokumpu flash smelting, Outokumpu direct high-grade matte smelting, INCO flash smelting, and Peirce-Smith converting processes. In this model, as much as 16 elements (Ni, Cu, Co, Fe, As, Sb, Bi, S, O, Al, Ca, Mg, Si, N, C and H) are considered. The compositions of matte, slag and gaseous phases, and heat balance are calculated using the thermodynamic data and the activity coefficients of the components derived from the experimental data. The model predictions were compared with the known industrial data from Kalgoorlie Nickel Smelter in Australia, Outokumpu Harjavalta Nickel Smelter in Finland and INCO Metals Company in Canada, and an excellent agreement was obtained. In this paper, the applications of NiModel in the nickel pyrometallurgical industries have been presented. NiModel has been used by Jinchuan Group Limited in China.

Jan 1, 2004

By Gus Van Weert

This paper describes the results of autoclave testwork where ferric nitrate was hydrolysed in the presence of certain cations and anions and the resulting hematite analyzed for foreign constituents. For the cations Zn++, Ni++, Cu++, and AI+++, selectivity factors of over 107 were found. Magnesium gave 3.106. These factors are calculated as Me/Fe in solution over Me/Fe in the hematite; Me representing the metal in ion added. As-a result of the testwork at Delft University of Technology, BUDELCO (the Netherlands electrolytic zinc producer) ran a series of ferric nitrate hydrolysis tests in the presence of 10 additional trace elements. Impurity levels were prejudiced on Me2 EPHA extraction of iron from their zinc circuit, followed by HNO3 stripping. Good selectivity against base metals was confirmed, but trace elements forming anions (As. Sb) and sulphate were incorporated in the hematite. These BUDELCO results are also presented.

Jan 1, 1995

By Lijun Lu, Honghui Fang

This article carried out the experimental study on using desulfurization ash in steel slag composite material. This was done by investigating the desulfurization ash content in formula one and formula two samples on the influence of setting time and strength of mortar. Through this study the following conclusions were reached for formula one: (1) a setting time of more than 10 hours is required, (2) a dosage of desulfurization ash of 1 ~ 2% is optimal, where flexural strength is reduced by 10% ~ 23% and compressive strength reduced by 5.7% ~ 16.4%. The conclusions of formula two were: (1) when the dosage of desulfurization ash is within 5%, the setting time is within 10 hours; (2) when the dosage of desulfurization ash is 1 ~ 2%, the flexural strength is increased by 5 ~ 7% and the compressive strength is reduced by 1 ~ 2%. The results show that the formula two is better.

Jan 1, 2015

By Frederick T. Wallenberger

"Laser assisted chemical vapor deposition (LCVD) is a new containerless fiber process whereby growth of small diameter fibers or microstructures (microsprings, microsolenoids) occurs directly from the vapor phase. The laser beam has a focal point adjusted to coincide with the tip of the growing fiber inside the reaction chamber. Since the growing fiber is not in contact with reactor walls or foreign materials, it is chemically pure, and suitable for optical uses and uses requiring high structural uniformity. Continuous fibers and multifilament yams are possible. The use -of high reaction chamber pressures (1-10 bar) and a small wavelength Nd-YAG laser made it possible to fabricate small diameter fibers at growth rates >1 mm/s. This paper describes the synthesis of single crystal, polycrystalline and amorphous fibers by LCVD, and provides a comprehensive analysis of phase transformations occurring during their fabrication.IntroductionLaser assisted chemical vapor deposition (LCVD) is a new containerless fiber process [1-10] whereby growth of small diameter fibers or microstructures occurs directly from the vapor phase. The laser beam has a focal point adjusted to coincide with the tip of the growing fiber in the reaction chamber (Figure 1). The diameter of the growing fiber corresponds to that of the laser focus. Depending primarily on the laser energy (Le., the temperature at the growing fiber tip), it is possible to obtain single crystal, poly crystalline or amorphous fibers by this method.Since the growing fiber is not in contact with reactor walls or foreign materials, it is chemically pure, and suitable for optical uses and uses requiring high structural uniformity. Laser assisted CVD is a potentially continuous process; continuous fibers and multifilament yams are possible."

Jan 1, 1994