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By Mariane Costalonga de Aguiar, Carlos Mauricio Fontes Vieira, Sergio Neves Monteiro

"This work evaluates the effect of incorporation of an ornamental rock waste into an industrial clayey body used for roofing tiles fabrication. Formulations with 0, 10, 20 and 30 wt.% of waste were prepared by replacing the sand in the industrial clayey body. The plasticity of the formulations was determined by the Atterberg limits. Specimens were fabricated by 18 MPa press-molding and then fired from 850, 950 and 1050°C. The specimens were tested to determine the water absorption, linear shrinkage and three points bending flexural strength. The results indicated that the waste improves the extrusion performance of the clayey body by decreasing its plasticity. The use of the waste was beneficial to the water absorption and mechanical strength of the fired clayey ceramic at 1050°C.IntroductionOrnamental rock is a natural resource available in the municipal area of Santo Antonio de Padua and located 150 km from the city of Campos dos Goytacazes, northe of state of Rio de Janeiro, Brazil. Intense industrial activity related to ornamental stones, especially gneisses, is traditionally occurring in the region. After mining, the flagstone is submitted to sawing to obtain blocks and then, after a manual operation, the final products are small flagstones [1,2]. During the sawing operation, a sludge composed of water and fine particles of rock is generated. A monthly production of 1000 tons of ornamental rock waste is estimated to be produced at Santo Antonio de Padua. The final disposal of this waste has brought serious environmental problems. Since most industries do not have an adequate sludge treatment, the waste is contaminating the soil and underground waters as well as obstructing rivers and lakes.Ceramic bodies industrially fabricated in the municipal area of Campos dos Goytacazes, 280 km from the city of Rio de Janeiro, are still empirically elaborated using a mixture of local clays. These clays are predominantly kaolinitic mineral, associated with high plasticity. Due to the excessive plasticity of the ceramic bodies, it is common to have dimensional defects in the final products after the drying and firing processes. Moreover, the kaolinitic structure and the presence of aluminum hydroxide confer a refractory behavior to the local clays. This impairs sintering during the firing operation. In the case of clay ceramics for civil construction, this results in greater porosity associated with elevated values of water absorption [3,4]. To avoid this problem, it is necessary to reformulate the ceramic body composition. The addition of both non-plastic materials to reduce plasticity and fluxes to condition the refractoriness is a possible alternative."

Jan 1, 2011

By K. W. Cathrine Solem

Filtration of liquid aluminium is widely used in the industry for the removal of inclusions, and Ceramic Foam Filters (CFFs) are often the filtration media of choice. It is known that PH3 (phosphine) can be released from used phosphate bonded CFFs when in contact with water. Additionally, there is a need of an improved understanding of the thermal stability and the chemical reactivity of these types of filters, as there is limited information available in the public domain. In the present preliminary study, three CFFs, i.e. Substrate 1–3, with varying AlPO4 (aluminium phosphate) content were studied under controlled conditions. Samples of the substrates, as produced and in contact with 5N pure aluminium, were heat-treated in a vacuum induction furnace at 850 °C and 1300 °C, as well as thermally studied at 850 °C using a Differential Scanning Colorimeter connected to a Thermogravimetric Analyser (DSC-TG). All tests were performed under an inert atmosphere of argon (Ar). Mass changes of ∼0.001 % were registered for the pure substrates, and 0.003-0.10 % when in contact with aluminium. In the latter case, diffusion of P (phosphorous) from the bulk of the substrate to the interface was established to have taken place. A colour change, from white to orange/brown, was also observed at the interface, which is a clear sign that a chemical reaction has taken place. As a result, the thermal stability of the substrates can be questioned under present conditions.

By S. M. Copley, M. Yankova, E. Y. Yankov, J. A. Todd

"Nanophased coupled growth structures, with spacings of -10 nm, have been observed in banded microstructures produced by laser melting hypoeutectic Ag-Cu alloys. These coupled growth structures comprised a Cu-rich phase of width - 1 nm and a Ag-rich phase of width - 9 nm. In this paper, microstructural observations of nanophased coupled growth structures in hypo eutectic AgCu alloys are presented. Laser beam velocities for the transition from banded to microsegregation free microstructures are modelled and compared with experimental values. Models are presented to show that, at a critical undercooling, initial growth of a Ag-rich, metastable, extended solid solution is rapid but slows to a halt as copper is partitioned into the liquid at the solid/liquid interface. Following nucleation, the coupled growth structure then grows until the partitioned copper is consumed, at which point growth of the Ag-rich solid solution is again accelerated. This cycle then repeats resulting in banded microstructures comprised of 750 nm of the Ag-rich extended, metastable solid solution, followed by 250 nm of the coupled growth structure.1. Structural Studies of Laser Melted and Resolidified TrailsPresented here are observations of laser melted and resolidified trails in Ag-Cu alloys obtained at beam velocities ranging from 0.7 to 34 cm S·I. When the laser beam is scanned along the surface (positive x-direction) with a velocity Vb a melt pool with the shape given in Fig. 1a moves with the beam. The isotherms move with the velocity, Vi,. = Vb cos.p. Calculations employing the thermal analysis of Kou, Hsu and Mehrabian [1] for the beam velocities of this investigation and for the thermal properties of AgCu alloys, indicated that, .p, the angle between the isotherm velocity and beam velocity should be small at the surface where microstructural studies were made. This prediction was supported by observations of trail cross-sections. Based on these observations, and the calculations which include latent heat effects, the isotherm velocity for observations near the surface in our investigation was taken to be 27 cm S-I."

Jan 1, 1994

By J. Huot

It has been shown that magnesium-based metal hydrides such as Mg2Ni could be synthesized by high energy mechanical alloying. This process creates a nanocrystalline alloy that has enhanced hydrogen sorption properties due to the high density of defects and grain boundaries. Unfortunately, this process also requires a long synthesis time (up to 100 hours in some cases). In order lo reduce processing time and cost of synthesis, we have investigated the effect of milling at elevated temperature under an inert atmosphere. Milling at high temperature improves interdiffusion of the elements and reduces the number of structural defects such as vacancies, dislocations and internal strain. It was found that by milling elemental powders at 200°C. a complete synthesis of Mg2Ni could be achieved in 8 hours. This synthesis time is roughly an order of magnitude lower than that of the process conducted at room temperature. The hydrogen sorption kinetics and capacity of this material are comparable to Mg2Ni synthesized at room temperature.

Jan 1, 2002

By Markus A. Reuter, Jacob Wood, Robert Matusewicz

Over the last 20 years, significant improvements in copper smelter productivity have been realized through the advent of continuous smelting processes. This progress has until recently however, not been carried through to copper converting. Peirce-Smith converting has been widely used by the copper industry for 100 years but is limited by its batch nature in achieving large scale of production. A logical next step is therefore copper converting on a continuous basis with its inherent environmental benefits. A number of continuous converting technologies are currently in use or being developed within the copper industry, the majority of these operating with calcium-ferrite slags. A notable exception however is the Ausmelt Continuous Copper Converting (C3) technology which has focused on operation with ferrous-calciumsilicate or loosely called olivine type slags. This paper discusses the merits of the Ausmelt C3 process and the advantages offered in terms of operational flexibility and process control arising from the use of lime modified iron silicate slags. It also examines the effects of key process variables pertinent to continuous copper converting from both a theoretical and experimental/operational perspective.

Jan 1, 2009

By Gabriel Riveros

Fire refining of copper consists of two stages copper oxidation and copper reduction. Very frequently the capacity of the anode furnace is determined by the rate of copper reduction. The analysis of factors affecting the rate of the oxygen reduction from a liquid copper with solid carbon or injected hydrocarbons pointed out the role of the mass transfer in a liquid copper in final stage of the reduction. Experimental results of copper reduction with graphite and injected natural gas in laboratory- scale crucibles showed two stages of the reduction process with a sharp change of the controlling mechanism. The estimated dynamic surface area of gas bubbles based on the measured bubble frequency and the gas flowrate allowed for the detennination of the reaction constant as a degree of the partial pre-combustion of the air/natural gas mix. The variation of the used reductant as a function of the oxygen concentration and temperature has been evaluated based on the detennined kinetic model. The intensification of copper reduction in fire refining has been discusses on the basis of obtained kinetic data and analysis of various factors detennining the time of reduction.

Jan 1, 2003

By C. D. Chapman

Current regulations regarding the landfill disposal of asbestos containing wastes are inadequate to ensure there are no ground water or airborne emissions. Accordingly, there is growing recognition that asbestos wastes can only be safely disposed of by using techniques that destroy the hazardous fibres. An innovative high-temperature plasma arc technology (The MAGRAM Process) is being developed for the recovery of magnesium metal from asbestos together with supplementary magnesia containing feedstock. The furnace will operate in. open bath mode with aluminium and/or ferrosilicon being employed as reductant. An important advantage of the process is that magnesium vapour within the furnace will be generated close to atmospheric pressure rather than at reduced pressure under which existing processes operate. Thermodynamic modelling work has been undertaken to define the range of slag composition and furnace temperature under which magnesium production at atmospheric pressure is feasible. The effect of slag chemistry, reductant addition, and temperature on product quality and yield have also been investigated and key aspects have been tested on bench scale. A 300 kW pilot plasma furnace unit has been employed for the treatment of calcined asbestos wastes. Aspects of design and operation of the unit are detailed. Acknowledgement: This work is substantially financially supported by the European Communities under the Industrial and Materials Technologies (Brite EuRam H) Research and Development programme.

Jan 1, 1995

By Rodney Hundermark

At Anglo American Platinum’s Polokwane Smelter, radar instruments are being used to provide continuous measurement of the concentrate feed level in the six-in-line electric furnace used for smelting of nickel-copper concentrates containing platinum group metals (PGMs). The radar instruments are installed directly on the furnace roof, and a mechanical system has been designed to protect them from radiation and elevated freeboard temperatures and pressures. Signal validation criteria have been implemented to ensure that proper level measurements are being used by the PLC system. The feedback from the radars has provided an improved understanding of the furnace behaviour with respect to concentrate feed level control, individual feeding events, global feed rates, feed distribution and bath disturbances. In combination with a dynamic mass balance for continuous calculation of liquid level in the furnace, the radar measurements have enabled more precise feedback control of the concentrate blacktop depth. In turn this has yielded improvements in furnace stability.

By Mark Khinkis, Huajun Yuan, Mark Zak, Yaroslav Chudnovsky, Aleksandr Kozlov

"An afterburner for green petroleum coke calcination in electrothermal fluidized bed was designed, fabricated, installed, and tested on a pilot fluidized bed calcination furnace. The experimental set-up comprised a combustion chamber, in which fine particles and volatiles of the furnace off-gas were fully combusted, and a cooler equipped to calculate the related heat recovery and losses. Off-gas composition was analyzed to evaluate the combustion process. The energy balance confirmed the potential to recover a large part of the heat value of volatiles and fme particles from the GPC. Potential future applications of the results are discussed.IntroductionGreen petroleum coke (GPC) is an oil refining byproduct that can be used directly as solid fuel or as feedstock for the production of calcined petroleum coke [1-2]. GPC contains a high amount of volatiles and sulfur. With coke calcination, the GPC is heated to remove the volatiles and sulfur in the calciner off-gas to produce purified calcined coke, which is used in the production of graphite, electrodes, metal carburizers, and other carbon products. Currently, more than 80% of calcined coke is produced in rotary kilns or rotary hearth furnaces. These technologies provide partial heat utilization of the calcined coke to increase efficiency of the calcination process, but they also share some operating disadvantages [3]. On the other hand, coke calcination in an electrothermal fluidized bed opens up a number of potential benefits for the production enhancement while reducing the capital and operating costs.The increased usage of heavy crude oil in recent years has resulted higher sulfur content in green coke produced from oil refinery process, which requires a significant increase in the calcinations temperature and residence time [ 4]. The calorific value of the process off-gas is quite substantial and can be effectively utilized for combined heat and power (CHP) production to complement the energy demand. Waste heat recovered from the product cooling could also contribute to the overall economics of the calcination process. Preliminary estimates indicated the decrease in energy consumption by 35-50% as well as a proportional decrease in greenhouse gas emissions. So, efficiency improvement of the coke calcinations systems is attracting close attention of the researchers and engineers throughout the world."

Jan 1, 2014

By Jan Yaozhong

The composition and the possible utilization of Ti bearing blast furnace from a titanomagnetite blast furnace smelter were studied. The slag contained about 20% Ti02 and trace Sc. The mineralogical analysis indicated that Ti in the slag is mainly as perovskite. By means of magnetite separation, the Ti containing phase could not be enriched. An effective hydrometallurgical approach was proposed with sulphuric acid leaching. The method proposed for processing the studied slag renders product Ti02 and SC203. Besides the recovery ofTiO2 and SC2O3' the leaching process yields fine grained residues which can used as additives for making cement.

Jan 1, 1996

By llya Perederiy, Vladimiros G. Papangelakis, Indje Mihaylov

"Nickel slags obtained from various smelting furnaces and converters differ in terms of their chemical composition and microstructure. The microstructure of the slag is largely affected by how fast the slag is cooled after being discharged from the furnace. Slow cooling is known to promote crystallization and growth of phases such as crystalline fayalite (Fe2Si04), magnetite (Fe3Ü4) and vitreous silica (S1O2). Slag granulation causes rapid solidification of the melt in the form of either an amorphous solid or highly intergrown crystalline silicate and oxide phases. Smelter slags contain entrapped Ni, Co and Cu in the form of dissolved oxides and matte inclusions. Extraction of the entrapped metals by high pressure oxidative acid leaching (250°C, 70 g/L initial H2SO4, up to 90 psi O2, 45 min) relies on the dissolution of the metal bearing minerals. The impact of the slag microstructure on the accessibility of these minerals to leaching, as well as the morphology of the produced residues is discussed in this paper.IntroductionIt was shown previously that entrapped base metals can be efficiently extracted from naturally cooled (as opposed to granulated) crystalline nickel smelter and converter slags using high pressure oxidative acid leaching operating at 250°C, ~40 g/L terminal acid and 60 to 90 psig oxygen overpressure [1, 2,3,4, 5, 6].Mineral characterization work performed on a naturally cooled crystalline nickel furnace slag from Vale's operations in Sudbury (ON, Canada) was previously reported [4]. Fayalite (Fe2Si04) and magnetite (Fe3U4) were detected using powder X-ray diffraction. These two minerals as well as silica (S1O2) and matte ([Fe,Ni,Cu]Sx) were also identified with the help of energy dispersive X-ray spectroscopy (EDX) on cross-sectional images obtained with a scanning electron microscope (SEM) operating in the backscattered mode. Nickel converter slags obtained from Vale's operations in Sudbury were found to be mineralogically similar to the furnace slag, but with higher contents of matte entrainment and magnetite based on the SEM-EDX observations [6]."

Jan 1, 2012

By E. Gratz, U. Pal, A. Powell, S. Pati, J. Milshtein

"The solid oxide membrane (SOM) process has been used at 1150 'C to produce magnesium by direct electrolysis of its oxide. Magnesium oxide is dissolved in a molten CaF2-MgF2 ionic flux. An oxygen-ion-conducting yttria-stabilized zirconia (YSZ) SOM membrane separates the cathode and the flux from the anode. During electrolysis, magnesium ions are reduced at the cathode and Mg(g) bubbles out of the flux into a separate condenser. The flux has a small solubility for magnesium which imparts electronic conductivity to the flux. The electronic conductivity decreases current efficiency of the process and also degrades the YSZ membrane. This study investigates different methods for reducing the electronic conductivity of the flux due to magnesium solubility. One effective method shown here is inert gas flushing near the magnesium nucleation site. Potentiodynamic and potentiostatic experiments along with AC impedance spectroscopy are used to characterize the effectiveness of the approach.IntroductionMagnesium is the third most abundant metal in the earth's crust. Since magnesium is the lightest of all metals used for construction alloys, magnesium is the leading candidate to replace steel and aluminum in automobiles. Automobile manufacturers would like to increase magnesium content from 4-5kg per vehicle to 40-IOOkg per vehicle [I]. Using magnesium alloys instead of steel and aluminum can reduce automobile weight and improve fuel efficiency. However, in order for automobile manufactures to make this change, it is generally believed that new cost effective methods of magnesium production must emerge.One approach for magnesium production which has been shown to be effective on a laboratory scale is the direct electrolysis of magnesium oxide utilizing an oxygen-ion-conducting solid oxide membrane (SOM), this is known as the SOM process [2]. A recent study estimated that a commercial SOM plant could produce magnesium from magnesium oxide at a cost that is 40% less than current technologies [3]."

Jan 1, 2012

By Somayeh Dashti, Ehsan Vahidi, Fereshteh Rashchi

"The main goals in zinc electrowinning process are decreasing of power consumption and increasing of current efficiency. In this study, the electrowinning of zinc in the presence of different additives in electrolyte were established and Arabic Gum, Gelatine, sodium lauryl sulphate and l-hexyl-3-methylimidazolium hydrogen sulfate in the five levels using Taguchi method was examined. In our previous researches, using orthogonal array, effect of zinc electrowinning parameters such as anode type, current density, sulphuric acid concentration, temperature and zinc ion concentration was studied and the optimized conditions for zinc electrowinning was obtained. Anode composition: Pb-Ag 0.5%-Sn2%-Sb1%, current density (A/m2):500, acid concentration (g/1):165, temperature: 60°C, zinc ion concentration (g/1):70. The main goals in zinc electrowinning process are decreasing of power consumption and increasing of current efficiency. ln this research, the effect of four additives: Gum Arabic, Gelatine, sodium lauryl sulphate and an organic material in the four levels with Taguchi method was examined. ln fact the effect of electrolyte environment and determining the best electrolyte under the optimized conditions is the main aim of this study.IntroductionDue to its low cost and abundance, zinc is widely used in the production of brass, galvanized steel, sacrificed anodes and primary and secondary batteries [I]. Some 80% of world primary zinc production is derived via roast-leach-electrowinning processes [2-4]. In the electrowinning process to both improve final product quality and current efficiency the leachate should be purified [5].To produce zinc a current method is to extractit from acidic zinc sulphate solutions by electrolysis with aluminum cathodes and insoluble lead-based anodes [6]. Though the electrolytic processing of zinc has been performed for many years, there are still current efficiency problems in the cathodic process. These low efficiencies (88- 93%) have a serious impact on the costs associated with the energy consumption. On the other hand, these low efficiencies increase energy consumption and decrease the quality of the surface morphology [7- 8]."

Jan 1, 2012

By I. A. H. Schneiderl

Eichhornia crassipes approaches being a scourge in many parts of the world, .choking waterways and hindering transport upon them. At the same time it is known to readily abstract heavy metal ions from water and, thus, aids in the removal of heavy metals found in such waters. This paper considers the possibility of using specific parts of the plant as an inexpensive adsorbent for the removal of heavy metals from contaminated chemical and mining industry waste waters. In particular the root of the plant was found to be an excellent accumulator of 'heavy metal ions including uranium from solution. It is. also suggested that dried roots of the plant ?might be placed in simple bags and used in a very low cost metal ion removal system.

Jan 1, 1995

By Carlos A. Nunes

V-AI alloys have been used commercially to produce pure vanadium by Electron Beam Melting (EBM), as well as to obtain Ti-based alloys (ex. Ti-6AI-4V). The aluminothermic reduction of vanadium pentoxide (V205) is the primary method to obtain these alloys. Concerning the obtention of pure vanadium, earlier studies have indicated alloys presenting Al content between 10 and 15wt% as the most suitable alloys for direct EBM. In the present work we investigated the aluminothermic reduction of V205 in order to define process parameters for the obtention of V-AI alloys with composition in the previously mentioned range. It was studied basically the effect of excess AI, CaO addition and reaction atmosphere (air, argon) on the alloy composition (AI, 0, N). In addition, microstructural analysis of selected alloys by SEM (BSE images) and EPMA (WDX) were also performed.

Jan 1, 1996

By Mohamad Omarei, S. M. Sadrameli

"The aim of this research work was to produce biodiesel (fatty acid methyl esters, FAME) from canola oil using KOH loaded on y-Al203 support as a heterogeneous catalyst. Different parameters such as effects of the molar ratio of methanol to oil, catalyst amount and reaction time on the yield were investigated. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used for characterization of the catalysts. A biodiesel yield of 86.67% was obtained under catalyst preparation and transesterification conditions of calcinations temperature of 773 K, 4 h of reaction time at 338 K, and using 3.5 wt% catalysts and molar ratio of methanol/oil of 15:1. The leaching of potassium species in the spent catalyst was observed.1. IntroductionBiodiesel is an eco-friendly and alternative energy source for diesel engines that can be synthesized by transesterfication of vegetable oil or animal fat with alcohols [1 ]. There are four principal approaches to the synthesis of biodiesel involving the transesterification of the triglycerides of the plant oils and animal fats: base catalysis [2], acid catalysis [3-5], employing supercritical alcohol conditions [6] and enzyme catalysis [7]. The commonly used homogeneous catalysts are NaOH, KOH and their alkoxides. Homogeneous alkali-catalyzed transesterification is much faster than acidcatalyzed transesterfication [8]. However, a large amount of water is required to transfer the catalysts from the organic phase to a water phase after the reaction. Therefore, it is considerably more costly to separate the catalyst from the produced solution [9]. These disadvantages could be removed by use of a heterogeneous catalyst [10]. The use of heterogeneous catalysts eliminates the neutralization step, hence it results much easier to separate from liquid products. Also, they can be designed to give a higher activity and selectivity and to have longer catalyst lifetimes [11]. A large number of different heterogeneous catalysts have been synthesized for biodiesel production. For example, calcined Mg-Al hydrotalcites [12], zeolite and metal catalysts [13], metal oxides such as calcium oxide (CaO) [14], magnesium oxide (MgO) [15], zirconium oxide (Zr02) [16], and supported catalysts [17] have been investigated as heterogeneous catalysts. CaO and MgO are most frequently used heterogeneous catalysts for biodiesel production [18]. In this present work, we aimed at developing an efficient catalyst for transesterification of canola oil. We have prepared KOH/ Al203 by impregnation and applied to determine the optimum conditions for biodiesel production. Three different variables including reaction time , alcohol to oil molar ratio and catalyst loading with may influence the quality of the produced biodiesel were optimized. Moreover, SEM (scan electron microscope), XRD (X-ray diffraction) and XRF were used for characterization of the catalysts."

Jan 1, 2012

By K. Moriyamo

Operation improvement efforts at Hyuga Smelting Co., Ltd. have focused on calcining capacity in the reduction rotary kilns ("the kilns"), whose limited feed rate capacity had capped production at around 18,000t-NiN since 1995. To improve the kilns' feed rate capacity of 80 wet t/hr, attempts were made to increase the gas flow in the kilns by increasing the capacity of the off-gas fans. However, as the increased gas flow resulted in only limited improvement of the kilns' feed rate, a scoop feeder was installed on each kiln to add coal to the middle of each kiln's interior to gain a higher efficiency of thermal supply and conversion. With these gas flow and coal charge addition operations, the kilns' feed rate capacity increased up to 120 wet t/hr, with burner fuel efficiency increasing by approx. 10% (approx. 5% in total with the additional coal included). As a result, production was raised to a level of 22.000t-Ni/Y Keywords: reduction rotary kiln, scoop feeder, additional coal charge.

Jan 1, 2004

By Chuanfu Zhang, Liwei Liang, Yanxin Wu, Jinliang Wang

"According to the reaction shaft operation characteristics during the flash smelting process, 15 groups of slag samples containing high Fe3O4 were prepared by some chemical reagents, and then the slag viscosities were measured using a RTW-10 type synthetic test instrument for melt physical property by the rotating cylinder method. The effects of Fe/SiO2 ratio (mFe/mSiO2), Fe3O4 content (wFe3O4), Cu2o), MgO content (WMgO) and Cao content (wCaO) on the slag viscosity were also studied. Results show that slag viscosity is decreased with the increase of temperature, mFe/mSiO2, wCu2o, wMgO and wCao, and with the decrease of wFe3O4, under the range of slag contents: mFe/mSiO2 1.36~1.78, wFe3O4 17.83%~21.18%, wCu2o 3.51%~8.34%m wNgI 2.21%~6.57%m w/caI 6.22%~9.387% and temperature range if 1250 o/c~1450 oC. Only wFe3O4m and w/caO have great influence on the slag viscosity when temperatures as high as 1400 oC. Only wFe3O4 and wCaO have great influence on the slag viscosity when temperatures as high as 1400 oC or so. To form a freeze slag with higher viscosity inside the reaction shaft, wFe3O4 should be more than 20% and wCaO should be less then 6%.IntroductionSince its appearance in 1949, Outokumpu flash smelting technology has making continuous innovation and has become the most competitive intensified smelting technology [1], widely considered to be the standard clean smelting process [2]. At present, flash smelting technology is adopted to newly build or reconstruct most of the world's copper or nickel smelting enterprise [3]. Reaction shaft is the most important part of the flash smelting furnace. During the flash smelting process, reaction shaft must be able to withstand the following harsh conditions at the same time: 1) high temperature varying from 1400 °C to 1500 °C. 2) strong oxidative atmosphere containing 50% - 80% oxygen. 3) solid particles and melt with speed up to l00 m/s. 4) high acidic or basic slag with strong chemical corrosiveness. 5) smelting gas containing 50% - 80% SO2. 6) matte with strong dissolution."

Jan 1, 2012

By C. J. Newman

Prior to 1995, the smelting process at the Kennecott Utah Copper Corporation (KUCC) smelter consisted of Noranda reactors and Pierce-Smith converters. In the consideration of expansion opportunities, the existing process did not lend itself to a program geared towards processing the total output of KUCC mining and milling operations. During 1989 and 1990, a number of smelting options were evaluated. The final selection was the Outokumpu flash smelting process, coupled with the new Kennecott-Outokumpu flash converting technology. Facilities were designed and installed to process 1:0 million tonnes per year of copper concentrate, with the ability to expand to 1.2 million tonnes per year. Following the shutdown of the smelter facility utilizing the Noranda technology in May 1995, the flash smelting, furnace commenced operation in June with the flash converting furnace startup following a few weeks later. The smelter has achieved design production targets and environmental goals. Current operating rates are at or above design rates for concentrate and matte processing. Emissions are lower than the permit levels and equate to less than 3.5 kg of SO2 per tonne of copper. This paper outlines the design, construction, startup and the first two years of operation of the modernized KUCC smelter.

Jan 1, 1998

By Batric Pesic

Silver dissolution with thiourea was studied by using the rotating disk technique. The major parameters studied were: thiourea concentration (0-0.5M), ferric sulfate concentration (0-0.5M), sulfuric acid concentration (0-0.5M), and the effect of many foreign ions (Mn, o.i, Co, Ca, Na, etc.). Temperature effect was studied in the range 5-35 .C. The activation energy was 5.4 Kcal/mole. The dissolution of silver was first order with respect to ferric sulfate, and the secord order with respect to thiourea. Among the additives, copper had a dramatically negative effect. The strong oxidants such as hydrogen peroxide and manganese dioxide were also detrimental for silver dissolution. Silver does not dissolve with thiourea in the absence of ferric ions. Sulfuric acid does not participate in the dissolution reaction either. Chemically, the most important parameter for silver dissolution is the ferric sulfate/thiourea ratio. Thus, in the solutions with excess of ferric sulfate, a solid silver-thiourea complex is formed, which precludes transfer of silver into solution. In the solutions with the excess of thiourea, the free thiourea reacts with formed solid silver-thiourea complex and silver goes into the solution. The solid silver-thiourea complex was characterized according to its chemical composition. The complex contains 6.54%C, 2.49\H, 14.77%N, 16.09%0, 21.62%8, and 37.13% Ag. This composition corresponds to a Ag2so4.3'1U.2ff:i0 compound The soluble silver species are present in the solution as the dimers of AgTU+3 complexes.

Jan 1, 1989