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By lonkion M. Font

Due to the known disadvantages of the use of iron silicate slag in the nickel converting stage, i.e., high metal losses, high magnetite content, and low fixation of impurities in the slag, the development of the new proposed "ferrous calcium silicate slag" for smelting and converting processes of nickel is very promising. Hence, considering the successful experimental results of using CaO base slag for the nickel smelting process, a study based on a detailed comparison for the phase equilibrium, and the minor elements distribution between the NilS2-FeS matte with either FeOx-CaO or FeOx-Si02 base slag was investigated. The main results are summarized as: no difference in the nickel losses between both slags was found at high nickel content in the matte, and the fractional distribution analysis for arsenic and antimony pointed out their preferential fixation in the calcium ferrite slag rather than in the iron silicate slag. Considering the energy and pollution issues, the technical feasibility of using calcium ferrite slag in a converting process of the Bessemer matte will have a prominent future for the nickel industry.

Jan 1, 2003

By D. Y. Wang, G. Y. Sha, X. L. Shen, D. R. Gu

The study of the volatilization kinetics of zinc and lead in pellets made of zinc-leadbearing dust mixed with coal powder, in a nitrogen atmosphere and at a temperature range between 1100 °C and 1300 °C, shows that the reduction temperature has a significant effect on the volatilization rates of zinc and lead, and that both the particle size of the coal powder and the extra carbon content has no effect on the volatilization rates. The obtained activation energies for the volatilization of zinc and lead are 79.42kJ/mol and 88.74kJ/mol respectively. The volatilization rate of zinc is controlled by the reaction between the zinc oxide and carbon monoxide while that of lead is controlled by the lead evaporation reaction, and the diffusion of gaseous lead through the gas boundary layer covering the surface of the reduced liquid lead.

Jan 1, 2000

By R. Hurman Eric

The dew-point technique of activity measurements take advantage of the volatility of a component in solution. The pressure of the volatile component over a sample is determined from observations of the temperature at which condensation of the vapor occurs. The method is applicable best when the vapor pressure of the components would differ by about two to three orders of magnitude. Experimentally, this is a closed system involving the use of evacuated and sealed transparent quartz sample probes. Furthermore reliable vapor pressure data of the volatile component is essential along with a specialized high temperature furnace capable of giving reproducible results. In this context, the vertical Dew-Point Furnace (DPF) was designed and built after elaborate trails until enough proficiency was gained for reproducible results. Over the years the DPF was modified and improved. The DPF developed was versatile and could easily be used for activity measurements in the isopiestic mode (another method of measuring activities of a volatile component in a solution). The necessary ancillary systems; namely evacuation-flushing-evacuation followed by sealing of quartz sample probes under vacuum were also perfected over the years. As and when necessary the dew-point technique was supplemented by classical equilibration-quenching method employed on the sealed quartz sample probes to reveal necessary phase equilibrium information. The following were studied utilizing the above technique: (i) Activities in CU2S-PbS and FeS-PbS binaries and CU2S-FeS- PbS ternary at 1200°C; (ii) Activities in Cu2S-SnS and FeS-SnS binaries and Cu2S-FeS-SnS ternary at I200°C; (iii) Phase equilibria and thermodynamic in Cu-Pb-S, Fe-Pb-S, Fe-Sn-S, Cu-Sn-S and Ag-Sn-S systems. Most recently the following systems have been tackled: (i) Phase equilibria and thermodynamics in the Ag-Pb-S and Sn-Pb-S systems; and (ii) Activities in Ag2S-FeS-CuzS-PbS quaternary at 1200°C.

Jan 1, 2003

In accordance with the new concept described in the paper presented at the TMS annual meeting in 1989, 1 a new zinc cellhouse was constructed and successfully operated. The new concept was proposed in order to reduce energy requirements and to mechanize the electrode handling in the cellhouse. Major modifications involved the use of an electrode unit consistfog of assembled anodes and cathodes with frame bodies between each cathode and anode. The space between a cathode and an anode could be halved by this unit structure. In this paper actual operation data are summarized and discussed in comparison with the calculated figures.

Jan 1, 1990

By L. Filip

The roast-leach-electrowinning (RLE) process for zinc was modified to treat two typical complex concentrates containing zinc, lead, copper, gold and silver. Laboratory testwork results indicated that the optimum roasting temperature ranged from 700 to 800°C, in order to produce acceptable residual sulfur levels. The calcined concentrate was subjected to a three-stage leach sequence. The resulting leach solution was purified by hematitic precipitation and directed to the recovery of copper and zinc by solvent extraction and electrolysis. Alkaline smelting and subsequent electrolytic purification recovered the lead and precious metals from the leach residue. A flowsheet was developed based on the laboratory testwork results, and demonstrated in a large-scale pilot plant. The recoveries produced during the pilot plant operation ranged from 90 to 92% for zinc and copper, 85% for lead and 90% for gold and silver, respectively.

Jan 1, 1999

By Gus Van Weert

Hydrometallurgical oxidation of sulphides is capital and energy intensive, with autoclave and bio-technology competing for lowest overall cost status. The use of surface aerators instead of stirred tank reactors could provide lower costs for bio-oxidation of concentrates. With this in mind, the Delft Inclined Plate reactor was designed with inclined plates above a settler shaped reactor to continuously return slurry from the lowest point in the settler to the surface of the liquid. The multiplate superstructure overcomes the scale-up restriction of the standard circular surface aeration patterns. DIP aerator energy and volume requirements for oxygen transfer from air will be presented in terms of kg O2/kWh and kg O2/m3/h transferred as a function of wt % sand in the slurry and compared to stirred tank performance. Scale up from the 4 m3 pilot unit will be discussed.

Jan 1, 1996

By Alexey T. Kovalev, Irina A. Khabarova, Valentine A. Chanturiya, Igor Zh. Bunin, Elizaveta V. Koporulina

"The paper presents new theoretical and experimental results about mechanisms of disintegration of mineral complexes and structural transformations of the sulfide surface under high-power nanosecond electromagnetic pulses (HPEMP). The heated gas outflow from nanosecond breakdown channels of sulfide minerals under HPEMP is considered. It is shown that the gas outflow from channels can be an additional destructive factor in the processes of the electric pulse discharge disintegration of mineral complexes. It is shown that the effect of HPEMP changes chemical surface composition and, respectively, technological properties of pyrrhotite and pentlandite. Morphology and elementary composition of new micro- and nanoformations on mineral surface of pentlandite and pyrrhotite have been investigated using up-to-date methods of SEM/EDX and Scanning Probe Microscopy. Preliminary electropulse effect on mineral products before flotation allows producing optimal conditions for flotation separation of pentlandite and pyrrhotite owing to forming the new nanophases and defects on the surface of sulfides.IntroductionThe effectiveness of High-Power Nanosecond Pulses in the disintegration and liberation of fine disseminated mineral complexes and the recovery of micro- and nanoparticles of precious metals from refractory ores was demonstrated in [1, 2]. Possible mechanisms of selective disintegration were considered in [1-3]. It has been shown both theoretically and experimentally that electric breakdowns can play an important role in the nanosecond pulsed treatment of milled minerals (e.g., semiconductor sulfides and quartz with particle sizes of 100 µm to 2-3 mm) that are carriers of finely disseminated gold and other valuable components. Electric discharges in such minerals are accompanied by a destruction of integrity in the form of breakdown channels and the formation of a system of cracks around these channels [3]. The development of the domains of induced cracks around the channels is determined by the pressure of evaporated material in the breakdown channel. Upon an instantaneous energy release in a channel (nanosecond discharges), the change in its transverse size and in the gas density and pressure in the channel is determined by (i) the radial motion of the evaporation wave, (ii) the radial expansion of the channel, and (iii) the heated gas outflow from the channel. The evaporation wave moves with a speed on the same order of magnitude as the speed of sound (or greater) and travels a distance of around the initial channel radius, i.e., a much smaller distance than the breakdown channel length."

Jan 1, 2011

By John A. Vallomy

"The CONSTEEL Process introduces a new concept in electric steelmaking by continuously feeding-preheating-melting and refining ferrous scrap or direct reduced iron. The process uses the furnace off-gas and fuel to preheat the scrap in a specially designed preheater. Thermal incineration of the flue gas reduces the carbon monoxide level to the more stringent requirements. Hot water or steam production from heat of flue gas is optional. The tap-to-tap time is set to match the cycle of the caster. The steel is treated via ladle metallurgy. The environment inside and outside of the steelplant is improved by decreasing levels of noise and hazardous emissions. Energy consumption decreases and disturbance to the electric network is eliminated. A CONSTEEL prototype was tested at Nucor Steel, Darlington, SC. A greenfield project is in the completion stage at the Florida Steel plant of Charlotte, NC, USA. The Process PhilosophyThe philosophy of the CONSTEEL Process is not solely to enhance efficiency; this was just a natural result of the change from a batch to a continuous practice. The primary objective in development was four-fold:1) 100% process control2) Rational use of available energy3) Improved environment inside and outside the plant4) Stability of energy input from the power systemIt was to make electric steelmaking more a science than an art and amenable to modern automation.The Basic Concept of CONSTEELThe concept of the process is shown in figure and includes basically a continuous feeding system, a preheater and a melting - refining furnace. A pre-established amount of heat is introduced into the scrap while traveling through the preheater using the sensible and chemical heat contained in the furnace off-gas and additional fuel. Melting-refining is carried out in the electric furnace. Slag formers, slag foaming additions and oxygen are injected to refine the melted steel continuously, to minimize the refractory erosion, to shield the arc, thus optimizing the transfer to the metal bath of the heat generated in the arc, to keep the bath homogeneous in composition and temperature and to produce carbon monoxide (CO) which is fuel for the preheater."

Jan 1, 1988

By Matthias Merzkirch, Volker Schulze, Kay Andre Weidenmann

"Unidirectionally reinforced light weight compounds based on light metals such as the aluminium alloy EN A W-6082 are adequate materials for the future use in transportation means like automobiles and airplanes. Due to the occurring cyclic loads knowledge about the crack growth behaviour of such composites is needed. The investigations at a load ratio of R = 0.18 show that the crack growth rate of the aluminium matrix is reduced if reinforced by spring steel wire with a reinforcing ratio of only about 1 Vol.-%. Additionally, the acoustic emission analysis allows detecting crack growth within the matrix material, crack propagation along the interface wire/matrix and crack closure which could also be determined with the help of a self designed capacitive displacement measuring gauge. The damage behaviour could be verified by metallographic and SEM investigations.IntroductionIn the field of lightweight structures for transportation means the need for light, strong and stiff materials, in particular composite materials, is increasing in order to save resources and costs. Lightweight materials such as aluminium and magnesium alloys are highly efficient candidates to be used in the composite extrusion process [1] which allows for a simple production of unidirectionally reinforced profiles with a large diversity of geometries at low costs. Figure 1 depicts the principle of the composite extrusion process; within the first part of the tool the billet material is split into several strands whereas the middle part of the tool allows the supply of the reinforcing elements. The third part of the tool rejoins the matrix material and the reinforcing elements and defines the final shape of the profile."

Jan 1, 2011

By Zhen Zhang, Jiang Diao, Xuan Liu, Tao Zhang, Bing Xie, Hong-Yi Li

Extracting vanadium from vanadium containing hot metal by LD process has been proven an effective solution for the utilization of vanadium-titanium magnetite ore, but the systematic analyses of vanadium extraction rate and mechanism by basic slag are seldom reported. In this study, mathematical model of vanadium transfer from metal to slag was formulated and the rates of vanadium extraction of hot metal with basic slag were investigated. The results indicated that the apparent vanadium extraction rate constant, kp, were in the range of 1.33~9.07×10-4g/(cm3·s). And the rate constant was increased with the increase of final slag basicity, reaction temperature and stirring gas flow. The apparent of mass transfer parameter decreases significantly from 0.13 cm3/ s to 0 cm3/ s in 20min, and the data changed as negative due to the decrease of slag oxidation and recovery of vanadium from slag to metal.

Jan 1, 2015

By Run-boWang, Fan-yi Meng, Jian-Liang Zhang, ZheWang

To elucidate the influence of high Al2O3 content on sinter softening and melting behavior, heating-up reduction test under load was carried out. In addition, microstructure study of sinter bed structure change at a different temperature was also made and the mechanism that the effect of Al2O3 content on sinter softening and melting property was discovered. SEM results showed that the increase of Al2O3 content favored the formation of Al2O3-rich slag phase, such as the eutectic (2CaO·SiO2-2CaO·Al2O3·SiO2-FeO) and gehlenite (2CaO·Al2O3·SiO2), resulting in the decrease of sinter Ts temperature. Further, high Al2O3 content improved the concentration of metallic iron and lowered the dripping temperature due to the decrease of slag liquidus temperature and viscosity. At a fixed basicity, it was indicated that there was a relationship between Al2O3 content and sinter softening-melting property. Based on the results, counter strategies to cope with the adverse effect of high Al2O3 content on the cohesive zone property were also proposed. It could provide guidance for the blast furnace operation of sinter with high Al2O3 content.

Jan 1, 2015

By Xiaojian Zuo, Yihua Han, Qingguo Xue, Jingsong Wang, Lintao Wang, Rongzong Lan

"Using the facility of reduction experiment, the low temperature reduction pulverization and reduction behavior of sinter in oxygen blast furnace (OBF) were studied. Through analyzing the results, the difference of pulverization and reduction behavior of sinter in OBF and conventional blast furnace (BF) were discussed. Furthermore, the effect laws of reduction temperature and the content of CO and H2 on reduction behavior of sinter were studied. Also the controlling step of iron oxide reduction was discussed. Compared with BF, the low temperature reduction pulverization of sinter became serious at 773 K; reduction rate became faster at 1173 K; reduction time became less and final reduction degree was increased in OBF. With increasing of H2 and CO contents, the reduction of sinter was promoted. The reduction process was controlled by interface chemical reaction at the earlier stage and by interface chemical reaction and internal diffusion at the final stage.IntroductionThe new ironmaking technology of Oxygen Blast Furnace (OBF) is most likely to be used in large-scale application process. The concept relies on the removal of the CO2 contained in the top gas of the blast furnace. Therefore the useful components, i.e. CO+H2, can be recycled back into the furnace and reused as reducing agents. In addition, injecting oxygen (O2) into the furnace instead of preheated air, removes unwanted nitrogen (N2) from the gas. Under the pressure of CO2 emissions in iron and steel making, the growing international shortage of coking coal resources and the rising price of coke, OBF has attracted attentions of both domestic and foreign researchers, because it has so many advantages such as high productivity, high PCI rate, low coke rate, high gas reducing capability and high top gas calorific value, etc [1-7]. As a result of recycling most of the top gas after CO2 removal and injecting oxygen into the furnace, the reduction capacity of blast furnace gas will be increased, so the metallurgical behavior of OBF's iron burden is different from traditional blast furnace. Therefore, it is one of the keys to develop this technology, which studies the metallurgical behavior of sinter in OBF. The purpose of this paper is to study the low temperature reduction pulverization and reduction behavior of sinter at the atmosphere of OBF, which includes the difference of low temperature reduction pulverization and reduction behavior of sinter in oxygen blast furnace and conventional Blast Furnace (BF). It will provide theoretical basis for the development of OBF."

Jan 1, 2012

By Michael A. Markowitz, Alok Singh

"Molecular self-assembly of phospholipids and other amphipathic molecules offers a versatile approach to form self-organized microstructures in various morphologies. Stabilization of microstructures in specific morphologies by polymerization renders them useful for practical applications in areas ranging from controlled release technology to template mediated synthesis of metals. Our efforts are focussed on the development of polymerizable biomembranes derived from phospholipids, their properties and utility e.g., as stable templates for studying chemistry at the lipid interface. Polymerized vesicles formed from mixtures of 1,2-bis(tricosa-1 O,12-diynoyl)-sn-glycero-3-phosphocholine, 1, with corresponding lipids having phosphohydroxyethanol,2, or -hydroxypropanol,3, headgroups have been used in electroless metal plating of vesicle surface with gold utilizing selective binding of Pd(NH3)4 2 + to 2 or 3. The surface bound palladium ion served as catalyst for metalization. Metalization of polymerized vesicles constructed from charge neutral diacetylenic phosphocholine,1, did not occur using this process. The headgroup structure of the negatively charged phospholipids and the degree of vesicle polymerization had an effect on the stability of the vesicles after metalization. Vesicles formed from a mixture of 1 with polymerizable diacetylenic phosphatidic acid, nonpolymerizable 1,2- dipalmitoyl phosphohydroxyethanol or 1,2-diacyl phosphohydroxyethanol (from soy lecithin) were not stable to metalization process. The metal coating of the vesicles was examined by electron diffraction and revealed that the gold metal on vesicles was polycrystalline and face centered cubic. The results demonstrate the utility of polymerized synthetic membranes as template for easy and efficient synthesis of nanoparticles. IntroductionPhospholipids, synthetic or natural, provide a simple and straight forward route to construct membranes in a variety of morphologies due to their inherent property of selforganization in the presence of water[1]. Vesicles are closed spherical structures comprised of concentric walls made from lipid bilayers. Vesicles are morphologically simple structures with enormous technological potential. Polymerizable phospholipids prepared by incorporating a polymerizable group in the molecules demonstrate physical properties comparable to their non-polymerizable counterparts and have the added virtue of providing enhanced physical and chemical stability to the membranes[2,3]. The size, shape and properties of the organized assemblies are dependent on the lipid structure and the nature of the aqueous environment[4,5]. The headgroup geometry, surface charge density, and spatial arrangement of the phospholipids are known to affect the surface behavior of the lipid membranes, which is evident through their interaction with other molecular (hormones, antigens, antibodies etc) or lomc species. Since phospholipid headgroup structure and charge can be modified either synthetically or by chemical perturbation of the aqueous medium (e.g., pH or ionic strength), phospholipid membrane surfaces offer a potential for developing novel strategies in those areas which involve the use of molecular reactive sites. One such strategy which could be envisioned explores the use of molecularly engineered phospholipid assemblies to design and prepare template structures to regulate formation of ordered materials [6]."

Jan 1, 1994

By A. Onozaki

The Iijima Refinery was put into operation in 1972 and today has an annual production capacity of 156,000 tons of SHG electrolytic zinc. At the Iijima Refinery, the recoveries of gold and silver are 98.0% and 98.2%, respectively. Gold contained originally in the zinc concentrates reports in the Cu-Pb-Ag residue produced in the residue treatment process. Silver contained in the concentrates is distributed between the Cu-Pb~Ag residue and the copper cake produced in the purification process. The Cu-Pb-Ag residue, which contains gold and silver, is sent to the Oyachi flotatfon plant of the Kosaka Smelter; about 82% of the gold and about 85% of the silver are recovered in the copper flotation concentrate.. In this paper, the distribution of gold and silver in the Iijima. Refinery is discussed and operational results of the Oyachi flotation plant are presented.

Jan 1, 1990

By David G. Dixon

A mathematical model is derived in dimensionless form which simulates the effluent concentration response of reagents from spent heaps under both fresh and recycled water rinsing. The model is based on dispersion from isochoric pathways distributed in length and cross-section, oriented normal to convection channels in ideal plug flow. The effects of heap height, rinsate flow, and initial reagent concentration are examined. It is shown that the rinsing cycle undergoes a distinct shift between fast and slow rinsing at a certain time depending on the amount of stagnant solution in the heap, and the distribution of dispersion pathways. Results of preliminary column rinsing tests on both agglomerated and unagglomerated ores are presented which partially validate the model.

Jan 1, 1994

By W. D. Cho

The slag chemistry in steel processing plays an important role in terms of the removal of impurities including alumina particles. In the present study, the dissolution of solid alumina particles in CaO-based fluxes at the temperatures between 1450 and 1550 °C has been investigated to determine dissolution kinetics and mechanism. Alumina particles were added directly in the slags and the size of alumina particles was measured as a function of time using optical and scaru;ling electron microscopes. The dissolution rate has also been obtained as a function of Si02, CaF2, MgO and MnO contents in the slags. The diffusion boundary layer between alumina and bulk slag phase has been observed and analyzed using SEM and EDX. In addition, some experiments have been performed for the dissolution of alumina in BaO-based fluxes.

Jan 1, 2003

By T. C. Goel, A. Venna, R. G. Mendiratta

"Processing of ferrites has gained tremendous importance in recent times to meet the high performance demands on ferrites in keeping with the fast emerging· technologies. The quality of ferrite powders has strong influence on ·the performance of final device. Fabrication· of high performing ferrite components requires starting ferrite powders of precise stoichiometry, purity and microstructure. It is difficult to obtain these attributes by the conventional ceramic method. The key to obtaining quality powders lies in the· solution techniques. With this in view soft ferrites have been prepared by a wet chemical process, known as the citrate precursor method, which involves the formation of citrate complexes of the constituent cations. The advantages of this process are the ease of preparation and close control of composition, homogeneity, purity and particle size. Electrical and magnetic measurements on lithium ferrites have shown resistivity higher by more than two orders of magnitude compared to that observed for samples prepared by the conventional ceramic method, and low magnetic losses, making the ferrites specially suitable for high frequency applications.IntroductionProperties of ferrites are known to be sensitive to .their processing technique. A small deviation in the compositional stoichiometry of the ferrite affects its properties greatly. Soft ferrites such as Ni-Zn, Mn-Zn and Mg-Mn. are well known ferrites covering wide-ranging applications [1,2]. Lithiiim ferrites have also assumed technological importance for microwave applications and are potential substitutes for the expensive garnets [3]. Lithium ferrites are often doped with zinc to tailor the saturation magnetization required at high frequencies. Lithium and lithium-zinc ferrites, however, present difficulty to processing due to the volatile nature of both the cation components, namely Li and Zn. These ions are volatile at temperatures > 1000°C which makes their processing difficult. One of the main considerations of high frequency performance of ferrites is the high eddy current losses which prevent the interaction of the magnetic field with the ferrite component and hence impair device performance. These losses can be reduced by having a material of high resistivity. Electrical conductivity in lithium ferrite has been attributed to electron hopping [4] between the two vaience states of iron, Fe2+ <=> Fe3+, on octahedral sites. Maintaining the + 3 valence state of otahedral- Fe ions is thus a prerequisite for achieving high resistivity. The resistivity of ferrites is normally found to be low when processed by the conventional solid-state or the ceramic method [5]. This is attributed to (a) extensive ball-milling employed in the method to mix the component oxides results in non-stoichiometric compositions due to introduction of additional Fe ions on abrasion of steel balls during milling, (b) high processing temperatures involved which result in significant volatilization of Li and Zn ions creating thereby oxygen non-stoichiometry which results in reduction of Fe3 + to Fe2 +, (c) large and non-uniform grain sizes. In the present work, preparation of Li and Li-Zn ferrites by a non-conventional method known as a citrate precursor method [6, 7] which requires lower processing temperatures and duration is reported. The method gives stoichiometric compositions on account of homogeneous atomic-scale mixing of the constituent cations via the formation of metal-citrate complexes mixed in solution state. The method is also capable of giving small grain size which aids the oxidation ofFe2+ ions."

Jan 1, 2000

By Manju Gurung, Birendra Babu Adhikari, Keisuke Ohto, Hidetaka Kawakita, Katsutoshi Inoue, Shafiq Alam

Novel bio-adsorbent gel was prepared by immobilizing functional groups of glycidyltrimethyl ammonium chloride, a kind of quaternary ammonium chloride, onto polymer matrices of persimmon extract for the recovery of precious metals such as palladium(II) and platinum(IV) from chloride media. It was found that this adsorption gel exhibits high selectivity to gold(III), palladium(II) and platinum(IV) over base metals such as copper(II) and iron(III) while crude persimmon extract, the feed material, exhibits high selectivity only for gold(III). From the adsorption isotherms study, the maximum adsorption capacities for gold(III), palladium(II) and platinum(IV) were evaluated as 3.30, 1.67 and 1.00 mol/kg, respectively. Those for palladium(II) and platinum(IV) are higher than those of simple quaternary ammonium chloride type of chemically modified persimmon tannin gel and commercially available anion exchange resin.

Jan 1, 2016

By D. Lambert

Process modeling for large deformation metal forming processes has been developed into a very successful tool in commercial applications during the last two decades. DEFOR.MTM is a well-known metal forming process simulation program used by many industrial and research institutions. Recent developments include the ability to model multiple deforming body behavior during multi-pass pack rolling and microstructure prediction during multi-pass shape rolling. This paper summarizes how DEFOR.MTM can be applied to a number of rolling processes and briefly describes preliminary work carried out using the ALE technique. Keywords: Simulation, Rolling, Pack, Shape, Microstructure, FEM, ALE, Tantalum

Jan 1, 2003

By Terry Gerritsen

Electrode control systems regulate power by physically positioning electrodes. Due to the size and weight of the electrodes, this is a slow process where power fluctuations of less than a few seconds are not fully corrected. Nickel laterite AC furnaces operating in high voltage, shielded arc mode typically incur frequent power variations of approximately +I- 20% around the power set point. To provide enhanced power control, Hatch has recently supplied, at commercial scale, a thyristor-switched reactance system called an SPLC. The SPLC incorporates predictive control software to operate furnaces at the maximum transformer rating by reducing the large power swings experienced without the SPLC. The resulting higher average power enables higher production, without increasing transformer or power plant capacity. A 60 MW production version of the SPLC has been commissioned on Falconbridge Dominicans&apos;s laterite nickel furnace, yielding excellent results with a 3 to I reduction in power fluctuations. Keywords: SPLC, AC Power Supply, Electric Furnace

Jan 1, 2004