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By James P. Bennett

EAF slag chemistry and its control have been recognized as important in producing quality steel at a low price for a number of decades_ EAF steel producers make lime and dolomite additions to furnaces, controlling the CIS ratios and sulfur pickup from the steel. Existing phase diagram data at 1600°C for CaO, MgO, FeO, SiO2, and Al2O3 was used to write a computer model optimizing slag chemistry for slag foaming and reduced refractory wear. The model, its development, and its use in an industrial steelmaking environment will be discussed along with how the model can improve energy efficiency. The importance of EAF mass balance to account for critical materials like Si in scrap and refractory wear using the model will also be emphasized_

Jan 1, 2003

By Chonghe Li, Xionggang Lu, Wei Xiao, Xingli Zou, Weizhong Ding

The reduction degree and rate of the initial ilmenite concentrate and pre-oxidation samples by hydrogen were investigated by using thermogravimetric analysis system. H2-TPR was used to detected reduction properties of the pre-oxidation products which were oxidized at different temperatures. The phase transformations and micromorphology changes during pre-oxidation and hydrogen reduction were identified by XRD and SEM. The FeTiO3 was decomposed into TiO2 and Fe2O3 at the temperature below 900 oC. With the temperature rising, Fe2TiO5 was the only stable phase in high temperatures. The reduction of pre-oxidation ilmenite concentrate was faster than the natural sample, which was attributed to the micropores generated on the surface of ilmenite concentrate during oxidation. The main phases of the reduction product were metallic iron, ferrous pseuodbrookite.

Jan 1, 2014

By Pingchao Ke

A crystalline polyferric sulfate (PFS) adsorbent was synthesized by oxidizing and precipitating ferrous ions under atmospheric conditions. The morphology, structure, composition and specific surface area (SSA) and adsorptive efficacy to As (III) of the adsorbent were characterized by SEM/EDS and TEM images, XRD patterns, FT-IR spectra, BET SSA analyses and adsorption experiments. The adsorbent presents as morphology of near-spherical aggregate and good crystallinity. A small amount of goethite co-precipitated with PFS in the case of the initial ferrous concentration of 1 mol/L and increased the SSA of the aggregates. The absorbent with co-precipitation of goethite showed good adsorption to As(III) and good filtering performance in the high As(III)-content solution of 10–100 mg/L under acidic, neutral and alkaline conditions (pH 2.09–9.01), and its maximal adsorption capacity and adsorption efficiency were 7911 μg/g and 96% separately. After Adsorption, the stability of the absorbents adsorbing As(III) were evaluated by TCLP tests, and the results indicated that the absorbents adsorbing As(III) were extremely stable, and the concentration of arsenic in all leaching solutions were less than 0.01 mg/L.

By James P. Bennett

EAF slag chemistry and its control have been recognized as important in producing quality steel at a low price for a number of decades. EAF steel producers make lime and dolomite additions to furnaces, controlling the CIS ratios and sulfur pickup from the steel. Existing phase diagram data at 1600°C for CaO, MgO, FeO, SiO2, and Al2O3 was used to write a computer model optimizing slag chemistry for slag foaming and reduced refractory wear. The model, its development, and its use in an industrial steelmaking environment will be discussed along with how the model can improve energy efficiency. The importance of EAF mass balance to account for critical materials like Si in scrap and refractory wear using the model will also be emphasized.

Jan 1, 2003

By Duclerc Fernandes Parra, Washington Luiz Oliani, Christiano Gianesi Bastos Andrade, Ademar Benevolo Lugão, Danilo Marin Fermino, Francisco R. Valenzuela Diaz

This work concerns the study of the effect of discarded bond paper on the mechanical behavior of polypropylene/organophilic clay nanocomposites. A brown polycationic bentonite from the state of Paraíba, Brazil, was treated with sodium carbonate to transform it into a bentonite that swells in water and then treated with hexadecyltrimethylammonium ammonium chloride to transform it into a bentonite that swells in organic liquids. Polypropylene with 3 % polypropylene graft compatibilizer (PP-g-AM) was mixed with 1 % and 2 % by weight of discarded bond paper and with 1% and 2% by weight of organophilic clay using a twin-screw extruder. The specimens were prepared by the injection process. The clay as received and after organophilization was characterized by XRD, SEM, and capacity of swelling in water and in organic solvents. The nanocomposite specimens were characterized by XRD and thermal analysis. The mechanical behavior of the injected specimens was evaluated by strength, flexural and impact tests. The nanocomposites showed improved mechanical properties compared with the polymer without filler.

Jan 1, 2015

By D. J. Droppert

This paper describes the precipitation-production of crystalline scorodite (FeAs04.2H20) from arsenic-rich sulphate-based metallurgical solutions at ambient pressure (95°C). Arsenic is precipitated by means of a controlled precipitation technique in which the supersaturation of the solution is carefully controlled. By controlling the supersaturation in the presence of seed material. the formation of amorphous ferric arsenate is prevented. Scorodite is known to be the most stable As(V) compound and is therefore preferred as host mineral for arsenic immobilization. The effect of the following parameters on the preCipitation behaviour and kinetics of scorodite are discussed: Type of base seed concentration initial [As]. sulphate concentration. neutralization rate. seed recycling and method of Fe(ll!) addition to Fe-deficient arsenic solutions.

Jan 1, 1996

By Lu Lin, Yanping Bao, Xiang Li, Linzhu Wang, Xiaobai Yan

The results showed the microinclusions were mainly Al2O3 and sulfide inclusions from tapping to the beginning of LF refining. Al2O3 inclusions were modificated into calcium aluminates after calcium treatment. Lots of spherical calcium aluminates composite inclusions containing MgO, TiO2 and MnS were found after soft blowing and during tundish metallurgy and left in the slab which caused the defects of beam plates. Pure Al2O3 inclusions were observed again after soft blowing 8min. Average sulfur content in inclusions decreased because of the high desulfurization ability of refining slag. Average Ca/Al ratio value in inclusions increased during LF refinging because of the reduction of CaO in slag by carbon and it increased obviously during the process of soft blowing 8min because of the dissolusion of calcium wire.

Jan 1, 2015

By N. Y. Ma

Solid wastes produced in ironmaking and steelmaking off-gas cleaning systems often contain zinc. The zinc level in these solid wastes is generally too high to recycle the wastes for iron through blast furnaces, but too low to economically treat the wastes for zinc through zincrecovery facilities. The behavior, status, and distribution of zinc in the ironmaking and steelmaking off-gas cleaning systems have been analyzed from three aspects: thermodynamics of zinc condensation, oxidation and deposition, correlation of zinc concentration with particle size and density, and aerodynamics of dust particles in the off-gas cleaning systems. Theory and supporting data show that spontaneous separation of zinc from iron-bearing dust occurs in the ironmaking and steelmaking off-gas cleaning systems. Dry off-gas cleaning systems provide the most favorable conditions and environments for zinc to separate from the dust. If highefficiency dry separators were applied and appropriately arranged in the off-gas cleaning systems, zinc would be concentrated, and the majority of the solid wastes could be recycled for iron recovery through blast furnaces.

Jan 1, 2008

By Michael J. Marinigh

"Increased safety requirements, higher operational costs, greater environmental restrictions, and new competitive processing techniques are the challenges smelter operators must confront in order to remain economically viable.In converting furnaces which have tuyères such as the Noranda Reactor and the Teniente, Peirce- Smith and Hoboken converters, efficient tuyère line management is critical to optimizing blowing rates, increasing refractory life, and improving safety.This paper will describe recent improvements made to equipment used for tuyère punching, tuyère silencing, tuyère pyrometry and refractory drilling of tuyères and how the proper application of the equipment can lead to operational and safety improvements."

Jan 1, 2009

By John J. Dunkley

Recent years have seen the increased use of hydrometallurgy in the smelting and refining of metals. However this is often used as a final refining step, following an initial pyrometallurgical smelting process. Huge amounts of material are produced as melts which have to be cast, comminuted, and taken up into solution or leached. A common method is to granulate the melt and then grind it. In the case of metallic melts this can be difficult or unfeasible due to the ductility of the granulated particles. Water atomisation is capable of replacing the granulation and grinding stages with a single process step that can process in excess of 30tlhour of melt into particles as fine as 50 microns. Applications in operation in Co, Cu, Ni, Ag, Au, Pt and Rh refining are discussed together with potential applications in copper smelting.

Jan 1, 2003

By Dilek Kirgöz, Onuralp Yücel, Murat Alkan

"In this study, Mo containing Fe-based alloys, such as Fe-Ni-Cr-Mo, were synthesized using a mixture of Fe203-NiO-Cr203-Mo03 powders reducing with Al powders by metallothermic process which is a high energy efficient, fast and low-cost production technique for synthesis of cast alloys and advanced ceramics. Detailed thermochemical studies were simulated by using FactSage 6.2 Thermochemical software in order to calculate adiabatic temperature of the reactions and effects of initial molar composition on the final products. In the metallothermic processes, effects of stoichiometric Al addition and addition of the oxide powders (Alz03, Si02, CaO, MgO) on the metal recovery and compositions of final alloys were carried out. Final products were characterized by using chemical analysis (AAS), XRD, XRF and SEM/EDS techniques.IntroductionSelf Propagating High Temperature Synthesis (SHS) has significant advantages compared to the high technology furnace applications, such as very short processing time, simple operation, low energy requirement and low cost [l, 2]. In a SHS process, the ignition starts the combustion and propagates throughout the reactant mixture yielding the desired product. However, the disadvantages of the process such as inhomogeneous or unreacted products due to undesirable reaction rates needs to be overcome by changing some parameters such as ignition temperature, particle size, additive, atmosphere etc. [3, 4]. This work aims to establish a scientific and engineering background in the production of some cast Fe based alloys (Fe-Ni-Cr-Mo) which are used as surface coatings, wear-corrosion-oxidation resistive applications via SHS (Self Propagating High Temperature Synthesis) metallurgy which is attractive process technique regarding fast and low-cost production ability of cast alloys."

Jan 1, 2013

By P. R. Taylor

Laboratory experiments have been performed to evaluate the kinetics of roasting pyrite and arsenopyrite in air at elevated temperatures, in the presence of lime. The effects of temperature, time, air flow rate, particle size, lime type, and mineral/lime weight ratio on the rates of oxidation, lime sulfation, and lime arsenation were studied. The reaction products were identified using chemical analysis, x-ray diffraction, SEM analysis, and optical microscopy. The results are discussed in terms of the utilization of lime to capture sulfur and arsenic during the roasting of refractory precious metal concentrates. More than 99.9% of the arsenic and 98% of the sulfur are contained when roasting pyrite and arsenopyrite with hydrated lime under typical roasting conditions.

Jan 1, 1991

By Jukka S. Sulanto

Outokumpu has applied its well -known copper Fl ash Smelling Process also for smelting su1phide lead . concentrates. The lead in the Flash Smelting Furnace slag is recovered by reducing the oxygen potential of the slag in an electric furnace by injecting reductant into the slag bath. A series of tests have been carried out in a 1000 KVA electric furnace? adjacent to a pilot Flash Smelting Furnace. The furnace has been fed continuously with molten Flash Furnace Slag. The feed rate has varied from 0.5 to 3.1 MTPH (0.55 - 3..4 STPH) depending on the feed rate and the quality of concentrate to the Flash Smelting Furnace. The inlet slag contained 15 to 40% of lead and the cleaned slag 1. 5 to 3. 0%. The lead recovery from sol id raw material was tested in the same continuous process by feeding lead calcine into the furnace. Feed rate was 0.7 to 0.95 MTPH (0.8 - 1.05 STPH) and the calcine contained 33 to 34% of Pb. Several reduction agents and procedures were tested. The process proved to be suitable for continuous recovery of lead from solid oxide raw materials.

Jan 1, 1990

By U .. C. Rojas, J .. C. Gomez

"Fire Refined Copper (EI Teniente Three Stars) has been produced at Caletones Smelter of Codelco Chile since almost the beginning of its operations.Due to changing features of the copper market, together with the targets on technical efficiency and productivity, it has become more and more relevant for copper industry to reach both, good final product quality and a proper environmental control.At present, copper refining process at Caletones Smelter takes place in two cylindrical tilting furnaces, where solid fluxes are injected through horizontal tuyeres into the molten bath. (Fig. N2 1)Solid reagents are pneumatically conveyed and injected into the liquid copper bath attaining excellent solid - liquid contact, so the impurities removal efficiencies are found to be high. Same injection tuyeres are used to introduce both oxidising agent (normal air) and reducing agent (reformed gas) into the molten bath. Air or nitrogen is used as conveying gas for solid reagents, depending on the process stage.This pap~r gives a fundamental description of the process and industrial results related to the injection of blend of sodium and calcium carbonates to remove arsenic and antimony, silica and granulated reverberatory slag to remove lead and a mixture of calcium carbonate and mineral coal to reduce the selenium content of the fire refined copper."

Jan 1, 1996

By Onuralp Yucel, Ahmet Turan, Halil Yildirim

"Nickel is mainly used in stainless steel production as ferronickel. In recent years, low grade ferronickel or nickel pig iron (NPI) is used in stainless steel production to reduce expenditure of nickel price. In this study, Turkey East Anatolian region lateritic nickel ores were directly introduced carbothermal reduction to produce NPI. Firstly the raw lateritic ore that contains 0.9% Ni, 0.054% Co and 2.3% Cr was mixed with metallurgical grade coal at different stiochometric ratios. The samples were smelted at 1600-1650 °C temperature range in an induction furnace for 25 min. In the second experimental set, different processes times were carried out from 15 to 35 min. The raw material, obtained alloys and slags were analyzed by using XRD (X-Ray Diffractometer), XRF (X-Ray Fluorescence Spectrometer), AAS (Atomic Absorption Spectrometer) and EPMA (Electron Probe Micro Analyzer) techniques.IntroductionNickel is an important element that has many application areas in the industry and there are a lot of kinds of nickel products such as refined metal, powder, sponge etc. 65% of metallic nickel is used in stainless steel, 12% is consumed as superalloy and non ferrous alloy because of its superior corrosion and high temperature properties [1].Nickel is a transition metal that is mined from mainly two types of ore deposits as sulphide ores and lateritic ores. Although 73% of nickel ores are laterites, 55% of primary production is from sulphide ores [1, 2]. The importance of lateritic ores is increasing due to the increase in nickel prices and decrease in reserves of sulphide ores.There are pyrometallurgical, hydrometallurgical and combined (pyro-hydrometallurgical) methods which are used for the extraction of nickel from lateritic ores. HPAL (High temperature pressure acid leaching) is generally used to recover nickel and cobalt from laterite nickel ores. It is suitable for the plants processing ores with low magnesium oxide and aluminum oxide content. Lateritic ores are exposed to hot acidic leaching around ~250 °C to dissolve cobalt and nickel under high pressure. The main disadvantage for HPAL is the high cost of titanium autoclaves. Process is complex and difficult to control due to the high pressure and heating of the process [2, 3 and 4]."

Jan 1, 2012

By R. Burkhard

Recovery of metals from complex mixed wastes is a challenging task of modem material and waste management strategies. Thermal methods are an important tool in this respect. Plasma turned out to be particularly useful for treatment of complex or toxic wastes and residuals. In order to study plasma processes at reasonable costs, a pilot plasma plant has been used and wastes like ~pent Raney-Nickel catalysts, copper and ah.:lminum drosses, and. other metal containing wastes were investigated. The paper summarizes the most significant findings

Jan 1, 1995

By M. Urda-Kiel

Stainless steel is increasingly used as a cathode starting sheet. It was shown earlier that even when depositing copper on copper, a substrate-influenced zone appears in the deposit structure, followed by a transition zone and finally by the electrolysis-influenced structure. On copper, the substrate-influenced zone has a thickness of twenty micrometers and on titanium, eventually more than fifty micrometers. Initial nucleation and growth have a considerable influence. In this paper, copper was deposited in a channel cell on four different 304 stainless steel substrates: mechanically polished and anodized, respectively, at 0, +400 and +800 mV/SHE in 1M H2SO4 at 20°C. Copper was deposited under electrowinning conditions after solvent extraction (SX) (40 g/l Cu++, 180 gh/l, H2SO4, 20 or 60°C). The results showed that, although Auger surface analyses of the substrates were only slightly different one from another including the oxide thickness, nucleation and initial stages of growth were very sensitive to the surface treatment of the substrate. Potential step and current step methods gave similar results : progressive nucleation followed by 3D diffusion controlled growth. The highest nucleation frequency was observed on stainless steel anodized at 0 mV/SHE, under various electrolysis conditions. The potential influence of these findings on industrial practice is discussed.

Jan 1, 1999

By Zhongning Shi, Ramana G. Reddy

"By cyclic voltammetry and potentiostat electrodeposition using Potentiostat/Galvanstat, electrochemical behavior on Ag electrode in electrolyte 0.2M NaOH+0.01MPb(NO3)2-0.01M TeO2 -0.01M TlNO3 solution were also carried out at 298K. The processes of electrodeposition of Tl2Te3 and PbTl4Te3, a thermoelectric material, are reported along with analysis of the composition of the obtained deposits. The results showed that two different underlying processes are occurring depending on deposition potential. One process involves the reduction of TeO3 2- and Tl+ to Tl2Te3 in a potential interval of -0.70V < E < - 0.89V (vs. Hg/HgO). A second process at more negative reduction potentials involves reduction of TeO3 2-, Pb2+ and Tl+ to PbTl4Te3 in a potential interval of -1.02V < E < - 1.19V. The crystalline Tl2Te3 and PbTl2Te3 were deposited electrochemically on Ag substrates at -0.84V and -1.10V respectively. Thermoelectric (TE) material can form a temperature gradient across the material to make electric voltage, which is popular in waste heat utilization and recovery industry. Lead telluride, PbTe, is a small band gap semiconductor of 0.32eV at 300K. PbTe can change its n-type semiconductors with Pb-rich to p-type semiconductors with Te-rich[1]. And it is one of the best TE materials used in thermoelectric generators working between 500K and 600K, or even at a higher temperature of 800K.Three facto,rs play a role in the performance of a thermoelectric material: electrical conductivity (s), thermal conductivity(?), and the Seebeck coefficient (S). These can be combined with absolute temperature (T) to give a figure of merit (ZT) for the material, ZT = s2sT/?. By increasing the electrical conductivity and decreasing the thermal conductivity, which can enhance the ZT value, many efforts, such as alloying with other elements and making the materials nano-sized, have been done to improve its properties recently. Hsu et al. reported that the ZT value of Cubic AgPbmSbTe2+m is increased to 2.2 by doping Ag-Sb to PbTe.[2]."

Jan 1, 2011

By Y. Iguchi, T. Narushima, T. Shiozawa, M. Maruyama, R. Arashi

"In situ observation system for thermal oxidation using Raman spectroscopy' was constructed, and oxide films formed on liquid pure Al and Al-Mg alloys (Mg contents = 1 and 4 mass%) were analyzed at room temperature to 1273 K in dry oxygen. In situ Raman spectra of the surface of a liquid Al-:-4mass%Mg indicated the formation of MgO • AlP3 (spinel) as oxidation products, while a -AlP3 and MgO • Alz03 (spinel) were observed on a liquid Al-1mass%Mg alloy. It was suggested that the formation of MgO film affected oxidation behavior of these alloys.IntroductionLiquid aluminum alloys are cast to ingots mainly by the continuous casting process. It is well-.known that surface cracks could be caused by oxide films formed on the surface of melt during continuous casting and defects due to the film. With regard to oxidation behavior of liquid aluminum alloys, many investigations l -s have been carried out from the view point of formation of ceramic metal composites(CMC) which are expected as cutting tools and structural materials 1.2. It is very important for reasonable continuous casting and CMC formation processes to elucidate oxidation behavior of melts.Oxidation behavior of materials generally depends on compositions and properties of oxide films formed on the surface. If in situ observations of oxide films are available during oxidation, evaluation of oxide films and interpretation of oxidation mechanism could be expected. Laser Raman spectroscopy is one of the most appropriate techniques for in situ observation of oxide films under various atmosphere at high temperatures. The authors have discussed the effects of atmospheres and sample compositions on oxide film formation mechanism on Fe-Si alloy6 and SiC-B4C composite7 on basis of an in situ observation by Raman spectroscopy. In spite of many previous studies, systematic and clear explanations have never been gotten on oxidation behavior of liquid aluminum alloys. And no in situ observation has been made except for transmission electron microscopy(TEM) and X-ray diffraction(XRD)."

Jan 1, 1996

By Filiz Sahin

This paper presents a synthesis of TiB2 via carbothermal reduction method using a mixture of TiO2, B4C and C prepared in molar ratio of 2:1:3. Reduction experiments were carried out in a high temperature graphite furnace in a graphite crucible under argon atmosphere at different time (0, 15, 30 and 60 min.) and temperatures (1400, 1500 and 1600 °C). The products obtained were investigated using XRD technique.

Jan 1, 2008