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By Chuanfu Zhang, Jinliang Wang

"Brickless reaction shaft is the latest progress for flash smelting furnace. However, there are many factors influence the melting point of the freeze slag inside brickless reaction shaft, and their variational regularities are not obvious, thus, it is difficult for conventional methods to analyze accurately the complex data. In this research, the experiment data of slag melting point were processed based on optimal discrimination plane. For this method, two orthogonal vectors were firstly built up based on the Fisher's criterion, and then the experiment data were projected onto the two vectors, thus, two-dimensional feature vectors were extracted as criteria to determine the factors effect degree on the slag melting point. Results show that the CaO content is the greatest factor to the melting point of the freeze slag inside brickless reaction shaft, the content of Fe3O4, SiO2, Cu2 O and MgO is the second, and the FeO content is the last.IntroductionBrickless reaction shaft is the latest progress of flash smelting furnace reaction shaft. To research the influence factors on the slag melting point inside the brickless reaction shaft is significant to form freeze slag with compact structure, good heat insulation, certain intensity, appropriate thickness and reasonable distribution, to extend furnace life, to reduce energy consumption, and to promote safe production.However, due to the complex components, there are many factors influence the melting points of the freeze slag inside brickless reaction shaft, and their variational regularities are not obvious. Therefore, it is difficult for conventional methods, such as variance analysis, data fitting, etc., to analyze accurately the complex experiment data.Pattern recognition can easily classify information, even if there are many influencing factors. For pattern recognition, there are some sub-disciplines such as discriminant analysis, feature extraction, error estimation, cluster analysis (together sometimes called statistical pattern recognition), grammatical inference, parsing and matching (sometimes called syntactical and structural pattern recognition) [1, 2]."

Jan 1, 2012

By Makoto Ohlsuka

The ternary Ni2MnGa intermetallic compound is an intelligent material which has both a ferromagnetic property and a shape memory effect (SME). The use of the shape memory alloy films for an actuator of micro-machines is very attractive because of its large recovery force. The purpose of the present study is to investigate the effects of fabrication conditions and to clarify the relationships between these properties and fabrication conditions of the Ni-Mn-Ga films. The Ni-Mn-Ga films with a thickness of nearly 5 um were deposited with a radio-frequency magnetron sputtering apparatus using a Ni50Mn25Ga25 or Ni52Mn24Ga24 target. They were heat-treated at various temperatures between 873 and 1273 K for homogenization and ordering and then cooled in a furnace. The composition of the films depended on the sputtering power. The as-deposited films were crystalline and had columnar grains. After the heat treatment the grains widened and the grain boundary became indistinct with the increasing heat treatment temperature. The martensitic transformation temperature of the heat-treated films increased with increasing nickel content. Furthermore the effect of plastic deformation and constraint aging on SME is also investigated. After plastic deformation, the two-way SME was shown through the martensitie transformation and its reversion, The intensity of X-ray diffraction peaks from stress-induced martensitie phase was found. The constraint-aged films also showed the two-way 3ME by thermal cycling.

Jan 1, 2003

By Baozhong Zhao

Laboratory experiments have been conducted on the removal of As, Sb and Bi from molten copper by SF 6 injection. The results showed that the impurities can be removed by SF6 injection in the? sequence of Sb >As >,Bi and the rate of Bi removal is affected significantly by the concentration levels of As and Sb in the copper melt. Analysis of the experimental data indicates that the impurity removal process is under chemical reaction control rather than by mass transfer of impurity through the molten copper phase. On the basis of experimental results, a kinetic model was developed and the order of chemical reaction and the volumetric chemical reaction rate coefficients of impurity removal were determined.

Jan 1, 1996

By Grégory Miette

The paper deals with a process that allows the recycling in a cupola of EAF dusts with 18 % Zn. It produces dusts with zinc grade higher than 50 - 55 % and commercial cast iron with less than 200 ppm Zn, 50 ppm Pb, 0.15 % S. The paper focuses mainly on lab tests made with the aim to develop an effective formulation of self reducing - melting pellets. With such a formulation, agglomerates develop a breaking load higher than 125 - 150 kg without any thermal treatment. Zinc and lead are volatilized in the cupola with yields higher than 95 % at 1200 OC, before any melting. Sulphur is transfemed into gas and slag. All these conditions allow to lower zinc, lead and sulphur grades below the cast iron specifications. Results of first bench scale tests performed at Fonderie Piret to validate the process will be presented.

Jan 1, 2002

By Shuqiang Guo, Xionggang Lu, Yuyang Bian, Weizhong Ding, Lan Jiang, Kai Tang, Changyuan Lu

For recovery of rare earth elements from the NdFeB based permanent magnet scraps, a high temperature process was used. Permanent magnets scraps were firstly oxidized in air. The optimal oxidation conditions under air are at temperature of 700oC holding for 30min. After the oxidation process, the oxides were reduced by graphite crucible at 1500oC under Ar atmosphere. By this way, the rare earth elements were recovered in the form of oxides, and Fe was separated to the metal phase. Boron distributed in both the rare earth oxides (REO) containing slag and the metal phase. In order to reduce the boron contents in the rare earth oxides, the carbon saturated iron bath and NdFeB added carbon saturated iron bath were used to refine the slag. By this process, the rare earth oxides with a comparatively high purity of 98.2% were gotten.

Jan 1, 2015

By R. L. Player

"The Copper Isasmelt process has been developed over the past 15 years by Mount Isa Mines Limited (MIM) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The first two commercial plants were commissioned in mid 1992.The results of four heat balances on the Mount Isa plant are presented. At a smelting rate of 98 t/hr of chalcopyrite concentrate plus 14 t/hr reverts, the total heat generated was -91MW. Approximately 39% of this energy came from coal, while 50% of the energy reported to the process waste gas. To a first approximation the furnace is near chemical equilibrium.The impurity distribution in the Mount Isa plant was presented. Approximately 91 % As, 85% Cd, 75% Bi, 68% Zn, 60% Sb and Tl, 45% Pb and 30% Te in concentrate was eliminated from the matte.The ""bubble"" frequency of the gas cavity below the foot of the lance was measured at -2. 1Hz. Side bands displaced by -l.lHz modulated the bubble frequency. This was consistent with radial gravity wave motion in the slag bath. The two processes, gas bubbling and wave motion appeared to be coupled together; the bubble frequency was twice the slop wave frequency. IntroductionCopper Isasmelt has been developed over the past 15 years by Mount Isa Mines Limited and the Commonwealth Scientific and Industrial Research Organisation. The process is based on the Sirosmelt lance, invented by researchers at the then Division of Mineral"" and ProcessEngineering ofCSIRO in 1973.The first two commercial scale copper furnaces were commissioned at Mount Isa and the Cyprus Miami Mining Corporation smelter at Miami, Arizona in August and June 1992 respectively.The process concept, the history of the development, and the Mount Isa plant have been described (1, 2, 3).This paper sununarises heat balances obtained on the furnace, the impurity distribution among the output streams and lance injection characteristics."

Jan 1, 1996

By S. Seetharaman

In the processing of molten metals, it is extremely important to monitor continuously the concentration levels of various minor elements, In the production of common metals like copper, iron and aluminium electrochemical sensors involving solid, as well as liquid electrolytes are being increasingly used to measure the concentrations of minor elements The present paper deals with the electrochemical principles underlying these measurements and the possible errors involved. One of the major difficulties in the case of the solid electrolytes is to correct for the consequences oldie electronic contribution to the conduction of the electrolyte. The application of the electrochemical sensors for molten metals processing involves designing of these probes to withstand the industrial operating conditions. In this respect, significant achievements have been made with respect to the design of oxygen probes for liquid metals in general and liquid copper in particular. Some of the salient design features are discussed in the paper, The application of auxiliary electrodes for impurities in molten metals like phosphorus in copper and silicon in iron are taken up. The development of oxygen sensors for slags is given special attention. Recent developments' in the field of sensor technology, as applied to metals processing are highlighted.

Jan 1, 1996

By Mototsugu Matsuno

A new process has been developed to treat fly ash generated from municipal incinerators, which contains not only toxic metals such as lead and cadmium, but also dioxins. The process includes the following steps; fly ash is formed into green pellets with some additives and the pellets are then roasted to eliminate or stabilize the toxic metals and to decompose dioxins. A pilot plant with a capacity of approximately 100 kg/hr was used to test the process, The tests verified that heavy metals were either volatilized or stabilized and dioxins were decomposed by high-temperature roasting. The pelletized ash was found to be non-toxic, so that it can be recycled as artificial lightweight aggregate. It was also found that volatilized metals collected as secondary ash can be recycled as smelting resources.

Jan 1, 2003

By Helfried Nafe

"For about a century thermodynamically absurd facts have been propagated in conjunction with the iron-carbon phase diagram. These facts concern fundamental relationships of chemical thermodynamics. Attention is turned here to the discussion of only one of the relevant aspects of the subject, i.e. the definition of the thermodynamic activity of the solute and its implications for the iron-carbon solution.IntroductionThe view on the iron-carbon solution is characterized by the assumption that the solute may appear in two different forms, i.e. graphite and cementite. Accordingly, two carbon solubilities are differentiated, on the one hand for graphite and, on the other hand, for cementite. As a consequence, two versions of the phase diagram exist simultaneously, the application of which depends on the prevailing conditions, (i) the so-called stable phase diagram with graphite as solute and (ii) the metastable one that is based on the cementite-in-iron solution. These diagrams are joined together in the double phase diagram that originates from Heyn [l ], with the first ideas mainly going back to Stansfield [2] and Charpy [3].Thermodynamically, the most inadequate implication of the Fe-C double phase diagram is that the carbon activity may take values larger than unity. With the standard state of the activity being that of the pure substance, i.e. the Raoultian one, such a value implies the nonsensical existence ofa state purer than pure. The explanation of this physical state, ifthere is any, vaguely refers to supersaturation and, in the wider sense, to the physico-chemical phenomenon of metastability. Other aspects of chemical thermodynamics are likewise involved. Therefore, the comprehensive investigation into the present subject requires more topics to be considered than only one separate issue. Not only should the criticism of the present view be in the focus but also the discussion of new ideas capable of reconciling the experimental facts, known about the F e-C system, with the fundaments of chemical thermodynamics. All this, however, cannot be provided here because of the limited space available. As a consequence, in what follows only a part of the whole problem is under scrutiny, i.e. the definition of the thermodynamic activity and its role for the interpretation ofrelevant experimental facts."

Jan 1, 2014

By Zhitong Sui

Based on several case studies on the precipitating behavior of valuable nonferrous metal compounds (VNMC) in molten slags a green technology for the recovery of VNMC from molten slags was proposed. This technology involves three steps: (I) The selective enrichment of the dispersed VNMC into the designed mineral phase in the molten slag; (2) The selective coarsening of the designed mineral phase to a critical grain size in the molten slag; (3) The selective separation from tailing of the grown mineral phase in the solidified slag by dressing or hydrometallurgy processes. This is a clean and low cost technique and has a great capacity to deal with a large quantity of slags. The utilization of the recovered VNMC such as Titanium, Boron, Vanadium compounds was summarized as examples of application. It was confirmed by experiments that the precipitating behavior of the designed mineral phases like Perovskite(CaTiO3), Suanite(2MgO*B2O3) and Sincosite(CaOoV2O5*P2O5) in molten slags is obviously affected by operation factors such as temperature, chemical composition, heat-treatment, additives and so on. The precipitating kinetics and mechanism of the VNMC from molten slags during solidification processes were also investigated.

Jan 1, 2003

By P. A. Botha

Most sinter producers prefer to use a range of iron ores with the aim to optimize their sinter blends. ISCOR is however limited to the use of ore from two deposits, namely Sishen and Thabazimbi. Only sinter produced from Sishen ore is described in this report. The Sishen iron ore deposit provides high-grade hematite ore with a mean iron content of 65 per cent. Three major ore types are developed: massive, laminated and conglomeratic. The main ore mineral is hematite with minor to trace amounts of quartz, mica, phosphates and, in places, carbonates. A sinter product is characterized by its mineralogical composition and metallurgical properties. The production rate also plays an important role in the economic evaluation of sinter quality. Sinter-pot tests were conducted with varying basicities, given as the ratio of CaO to SiO:< and coke content. The results of these tests were characterized by mineralogical and metallurgical methods. Basicity of a sinter mix directly influences the mineralogical composition and metallurgical properties. The content of calcium ferrite and calcium silicate increases with increasing basicity, thereby increasing the reducibility and cold strength of the sinter product. Experiments performed during this study provided a model for the optimization of the sinter mix with respect to its mineralogical and metallurgical parameters.

Jan 1, 1991

By Arsenio Enriquez, Adrian Deneys

"Rio Tinto through its subsidiary Kennecott Utah Copper Corporation (KUC) and Praxair have implemented the CoJet® gas injection system for copper anode refining. The system provides the capability to melt on average 60 to 70 tons of scrap copper per heat (with acceptable NOx emissions). The system has demonstrated the potential for tuyere-less sulfur and oxygen removal using coherent jet technology.This paper describes the process concept, system development, laboratory testing, implementation, current operation and ongoing developments."

Jan 1, 2009

By K. Osseo-Asare

Aqueous stability diagrams (25°C) are presented for the systems M-H2O and M-Oxalate-H2O where M=Sm, Nd, Co, and Fe. With the aid of these diagrams (i.e., Eh-pH and log[Metal]- log[Oxalate]), the solution-chemical constraints on metal dissolution and precipitation are identified. By comparing the corresponding stability diagrams, conceptual flowsheets are developed for metal recovery from Sm-Co and Nd-Fe-B magnet scrap.

Jan 1, 1997

By H. Cui

Rapid technological development has caused an increase in the demand for rare earths. Ancylite, a strontium rare earth carbonate, is a potentially significant source of rare earths. In this research paper, essential aspects of the magnetic separation and flotation processes for Bear Lodge ore are presented. A flowsheet is proposed based on an optimization of the variables and flotation simulation. The economic feasibility of the proposed processing operation is analyzed.

By R. M. Lamya

A considerable part of gold encapsulated in some refractory sulphides can be dissolved during sulphide matrix decomposition in non-complexing aqueous media. This has been concluded from laboratory results of gold extraction from pyritic and arsenopyritic concentrate containing 172.8ppm Au, into 10% hydrochloric, sulphuric and nitric acids. The degree of sulphides decomposition in the non-oxidative acids limits the gold extraction from this specific concentrate to about 10%. In the case of nitric acid, the gold dissolution follows the rapid decomposition of sulphides, reaching 32 to 42% of extraction at almost total decomposition of the sulphidic minerals. Accumulation of gold in this acidic and non-complexing solution to several ppm was not affected by the soluble products of the sulphides decomposition. An attempt to explain this gold behaviour is undertaken and some practical implications are discussed. In the investigated concentrate the "soluble gold" is mostly associated with arsenopyrite. This is consistent with the latest findings of other authors that gold disseminated in arsenopyrite can occur as cation Au3+. In a comparative test the gold extraction into highly concentrated chloride solution, in the same oxidative conditions, amounted to 92.34%.

Jan 1, 1995

By A. E. Isaacson

The U.S. Bureau of Mines is studying the effect of supercritical water, at 400&apos; C and 3,500 psi, and subcritical water, at lower temperatures and pressures, on mixtures of minerals and metals to determine the possible applications of water at high temperature and pressure for processing these materials. This research was conducted using a flow-through bench-scale system. Copper-bearing minerals studied were chalcocite, chalcopyrite, covellite, and cuprite. In general, mixtures of copper minerals and pyrite reacted to form bornite. Intermediate phases formed were chalcopyrite and digenite. Similar reactions occurred between pyrite and metallic copper. A mixture of chalcopyrite and pyrite was inert in supercritical water&apos;. The reaction between cuprite and metallic zinc yielded metallic copper. The cuprite was reduced by hydrogen generated by the reaction between metallic zinc and water. None of the reactions occurred exclusively in supercritical water, but also occurred in water at high temperature and pressure below the critical point. &apos;Experimental results did show that a dual-reaction process, consisting of solid-state diffusion and fluid transport, was occurring.

Jan 1, 1989

By Mansoor Barati

The present paper is based on a term project for final year undergraduate students, requiring them to evaluate a process for producing silicon from rice husk. The traditional method for production of silicon involves carbothermal reduction of quartz in electric arc furnaces at temperatures exceeding 2000 °C. The technology consumes a considerable amount of electrical energy as well as fossil fuels, resulting in significant CO2 emissions. A flowsheet for production of silicon metal from rice husk is laid out in this paper. The technology will consist of combustors, which will generate steam using the rice husk biomass, power generator, and electric furnace for reduction of the rice husk. Materials and energy balance calculations presented here indicate that such process can be operated independent of external electricity.

Jan 1, 2014

By George E. Cook, Peter C. Levick, Francis M. Wells

"Relationships are established between the peak current of a pulsed, rectangular current waveform and the pulse current duty cycle under conditions of constant arc power. By appropriate choice of these interrelated parameters, it is shown that the arc pressure may be varied over a wide range even though the arc power is held constant. The methodology is suggested as a means of countering the effect of gravity in 5-G welding, while maintaining constant heat input to the weld. Combined with appropriate penetration sensors, the methodology is additionally suggested as a means of controlling penetration. IntroductionBoth low frequency pulsation (typically 0.1 - 20 Hz) and high frequency pulsation (> 100 Hz) are often used with GTA welding. Benefits derived from pulsing include improved weld quality and better process control.Advantages cited for low frequency pulsation include claims that the total heat input to the weld is reduced, the weld bead size is reduced, weld penetration is increased, grain size is reduced, porosity is reduced, weld distortion is reduced, thinner materials can be welded successfully, and the tolerance of the welding process to material and production variations is improved (1-16). With respect to the latter, pulsing aids control of weld bead penetration by increasing the tolerance to component dimensions and joint fit-up. It also reduces the sensitivity to disparities in heat sink, and it helps to reduce distortion in thin section material or distortion attributable to poor clamping. In certain materials it can reduce the sensitivity to surface oxides and to cast to cast compositional variations (16). Low frequency pulsation is also useful in welding thick materials mated by a prepared groove. In these applications the low frequency pulsation is used to obtain proper sidewall fusion as the tungsten electrode is weaved from one side of the groove to the other. In this case the weld current pulsation is synchronized with the cross seam weave pattern, such that the high current pulses occur at each sidewall. This type of low frequency pulsation has proven particularly useful in welding with narrow width groove designs (17-21). Finally, Ecer (22) has shown that the pulsed current arc is more stable against magnetic disturbances than an equivalent constant current arc."

Jan 1, 1986

By A. McLean, Y. Uchida, M. Iwase, M. Myochin, K. Wiikimoto

"Phase diagrams of FeO-containing ternary systems could be derived from experimental data for the activities of FeO. The systems investigated are CaO-CaF2-FeO, SrO-SrF2-FeO; BaO-BaF2-FeO, CaO-CaCl2-FeO, SrO-SrC12-FeO, BaO-BaC12-FeO, CaO-A12O3-FeO and BaO-SiO2-FeO.IntroductionThe importance of phase diagram cannot be overemphasized. In a book, ""Alloy Phase Equilibria""[l], the author, Professor A Prince, states, ""A metallurgist has been defined as a person who thinks in terms of phase diagram"". Whether one accepts this statement or not, it is self-evident that an ability to interpret phase equilibria is essential to the professional metallurgists.The physical chemistry studies of iron and steelmaking process often require phase diagrams of FeO-containing slags. Iso-thermal section of the phase· diagrams of such systems can be derived from experimental data for chemical potentials of FeO. Due to the recent developments in the area of solid state electrochemistry, rapid determinations of the FeO activities have become possible. The present paper is aimed at documenting the derivation of the phase diagrams of FeO containing slags.Experimental AspectsAn electrochemical method incorporating stabilized zirconia can be used for the measurements of the activities of FeO in various slags and fluxes[2]. For the details of the experimental technique, reference should be made to reference 2"

Jan 1, 2000

By Kafui Nyavor

Acid mine drainage (AMD) is presently the biggest single environmental problem facing the mining industry. New and expanding metal mines in most parts of the world have to demonstrate their ability to contain this problem to obtain operating permits. Conventional methods of controlling acid mine drainage have primarily been limited to collecting the drainage and neutralizing with alkaline materials which do not provide a permanent solution to the AMD problem. Since acid mine drainage results from the oxidation of sulfides in the presence of oxygen, water and iron-oxidizing bacteria, controlling any of these three factors contributing to pyrite oxidation provides a potential at-source remedy for reducing or preventing acid mine drainage formation. Physical properties such as hydrophobicity also play an important role in the attachment of bacteria, adsorption of oxygen, water, and other ions that subsequently lead to the oxidation of pyrite. In this communication, the suppression of pyrite oxidation by treatment with fatty acid amines (FAA) was investigated. The FAA treated pyrite samples were tested at various conditions of temperature and pressure. At an elevated oxygen pressure of 500 psi and a temperature of 600 C, less than 0.2% oxidation was obtained for the FAA treated pyrite samples, while over 1.2% oxidation was obtained for the untreated samples in 10 hours of oxidation time. Accelerated column oxidation tests at ambient condition showed that FAA mated samples reduced pyrite oxidation by at least 75% in 81 days.

Jan 1, 1994