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By Vladimir Mindin

Simulation of complex equilibria is usually done in the P-T-X coordinates, where "Xu is the amount of individual chemical components in the system. This approach is not productive in some very important cases: (i) investigation of "open" systems, (ii) determination of coordinates (trajectories) of mono-variant points, among others. To solve these and some other problems, we use the idea of chemical potentials of elements (CPE) of the system. A system of different coordinates axes (CPE-axes ) leads to a new strategy of simulation, observing the results of the simulation, and to efficient technology of compressing and storage the data of the simulation.

Jan 1, 1994

By Joner Oliveira Alves

The aim of this work was to study the use of steelmaking slag as raw material to the production of rock wool and glass wool. Firstly, the chemical composition of the slag was analyzed. These results were used to infer the amount of additives to assemble the charge for the experiments. A laboratory-scale electric furnace was used to melt the mixtures used as charge. The melt material were turned into a water filled recipient, this process was performed in order to impose a fast freezing that is a characteristic of mineral wool production. Finally, with the rest of the melt material it was performed the Herty Viscosity Test. Samples of the produced material were characterized by different analyses. The results found in this research may lead to a technological innovation, because they indicate that the use of steelmaking slag to produce rock wool and glass wool is possible.

Jan 1, 2009

By P. J. Mackey

Over the course of Dr. Robertson’s career, the ferrous and non-ferrous plants have seen enormous changes in technology and increases in plant capacity, essentially amounting to a “technological revolution”. In iron and steel, the “mega” blast furnace of some 6,000 m3 working volume is now standard (~10,000 tonnes (mt) of pig iron/day). Similar huge changes in process technology and plant size have occurred in the non-ferrous industry. As an example, the fuelfired reverberatory furnace, once the mainstay of the copper industry, has disappeared - replaced by large capacity flash and bath smelting technologies. The energy consumption per unit mass of metal produced has also been reduced considerably. Our understanding of the thermodynamics and mechanisms of metallurgical reactions, a field to which Dr. Robertson has significantly contributed, has made great strides. This paper reviews these changes with particular reference to the copper smelting industry, providing also comments on expected future trends.

Jan 1, 2014

By Frederic Pineau

Semisolid metal alloys have a special microstructure of globular grains suspended in a liquid metal matrix. This particular physical state of the matter can be exploited to produce near-net- shape parts with improved mechanical properties. However, the behavior of the slurry is strongly influenced by the local solid fraction and state of agglomeration. Different flow instabilities ·associated with the combined flow and solidification process result, which make difficult the application of semi-solid processing in the casting industry. Moreover, the rheology of semisolid materials is not well understood. Most of the theory has been derived from experimental data, which are somewhat difficult to measure. A model that accounts for the multiphase nature of semisolid slurries is required to get more insight into such complex flows. This paper describes a mixture model for semisolid slurries. It assumes that the mixture of liquid-solid components behaves as a single fluid as far as overall mass and momentum balances are concerned. The coupling force between the phases is derived on the assumption that the slurry is a fluid saturated isotropic media. The proposed methodology is implemented in a finite element code. The model is then applied to the the filling of an industrial-scale capillary flow viscometer. Segregation patterns are obtained and discussed.

Jan 1, 2001

By André Laplante

The mineralogy of the Joe Mann mine differs from that of other deposits of the Chibougamau area that are exploited by Les Mines Camchib Inc.. It is characterized by very fine first generation gold and very coarse second generation electrurn. Successful milling required adjustments of the processing flowsheet, which includes gravity, flotation, and cyanidation. A study of coarse gold liberation in the gravity/grinding circuit is described. Modifications to the flotation circuit and the reconditioning of a small capacity cyanidation circuit are presented. As a result of the circuit modifications, gold recovery increased from 65 to 81% in flotation and cyanidation. Overall gold recovery increased from 77% to 88-89%. These improvements are mostly attibutable to the recovery of -10 urn gold, whose presence in the Joe Mann ore and original circuit tails had been identified by process mineralogy.

Jan 1, 1989

By L. L. Sutter

Fly ash is a by-product produced from the combustion of most hels including municipal solid waste. Currently, most combustion residuals are disposed of in landfills at a continually increasing cost and with questionable impact on the environment. Due to the presence of heavy metal compounds, municipal waste combustor (MWC) fly ash has the potential to leach these metals (e.g., lead and cadmium) above regulatory limits. The heterogeneous nature of MWC fly ash makes detailed characterization difficult. This research focuses on the identification of lead compounds in MWC fly ash. Samples obtained from the Olmsted Waste-to-Energy Facility in Rochester, Minnesota were examined in this study. The fly ash was fractionated into six size ranges and prepared as geological thin sections for analysis. The worked discussed in this paper involves using an electron microprobe analyzer to determine phase composition in MWC fly ash. In addition, backscattered electron imaging, digital image processing, and mineral liberation analysis software were used to determine phase distributions and phase associations as a function of particle size. Several lead containing compounds in several forms are identified. The results of this study show that lead can be identified in small sectioned particles which would not be apparent using normal backscattered electron imaging.

Jan 1, 1994

By G. E. Lagos

This paper analyses the scope and instruments employed by the Basel Convention for regulating the transboundary movement of hazardous wastes, the present and projected hazardous waste regulations of Chile, reviews the Chilean import/export trade of wastes of the period 1985-1995, and discusses, the influence that the Basel Convention has had on mining trade, its perceived benefits and costs, and possible effects on Chile's trade of the application of the Convention's Decision III/l. There is no quantitative estimation as to the effect of the Convention on the general volume of imported or exported materials destined for recovery, recycling, reclamation, or reuse. All recycling imports, with the possible exception of residues of petroleum oil, which occurred during the decade 1985-1995, can be classified tentatively as non hazardous. The entry into force of the Convention has had several effects on Chile's trade. It has brought home the need to have a comprehensive hazardous waste legislation, it has been a base for applying import restrictions, which in all likelihood, would .have otherwise not been applied, The benefits and costs of this import restriction, as well as those of the multilateral export ban are analyzed.

Jan 1, 1999

The cleaning of copper containing fayalite slag using a CuFe alloy was studied under an oxygen pressure ranging from 10-7 to 5 X 10-11 atm at 1200º c. The reduction of copper from fayalite slags by Cu-Fe alloys was found to be very effective. For example, at a P 02 of 10-7 atm, the copper content in the slag was reduced from 4.1 to 0.402 wt. percent after 90 min. of reaction time using a Cu- 5.27 wt. percent Fe alloy. The copper reduction rates were found to be independent of P02 in the gas phase when using Cu-Fe alloys which exhibit an iron activity of greater than 0.4. A mechanism for slag c1eaning is proposed based on the concept that the Cu-Fe alloy lowers the oxygen potential of the slag according to Eq.1 1, fol1owed by the reduction of cuprous oxide by wustite as shown in Eq.2. Here X represents element X in the alloy phase while (X) represents the element in the slag phase. The copper and iron transfer behaviour obtained in this study are explained by a ?Stepwise equilibrium model.

Jan 1, 1985

By N. B. Gray, A. E. Guerra, D. E. Morton

"The formation of splash in pyrometallurgical operations that involve the injection of gases into a liquid has been the subject of a number of studies over the last few decades. Given the complexity of the phenomena, there have been some advances in understanding the microscale formation of splash but the ability to accurately predict the amount and character of the splash formed is still in its infancy. First, the macroscale mechanisms for splash formation is very varied. Second, the timescales for splash formation are very small, usually less than 100 milliseconds, making experiments elucidating the formation of splash difficult and costly. Work at the GKW CRC has shown that the microscale mechanism of splash formation is primarily is due to the Kelvin-Helmholtz instability. Substantial progress has been made in understanding the behaviour of large bubbles in effecting splash formation and a simple model has been developed to estimate the behaviour of splash formed from a top submerged lance. Direct numerical computation of splash formation using the GKMAC codes developed at the Centre has been successful in simulating the impact of liquid drops onto a liquid bath.IntroductionInjection of gases into melts is used in the metallurgical industry to promote mixing to ensure acceptable heat and mass transfer rates, conveying solids for alloying, provide efficient contact for gas-melt reactions, and as a reactant. High gas injection rates bring about the formation of splash and slop. Extensive splash formation leads to loss of valuable product, creation of safety hazards, formation of accretion on refractory lining and exhaust ducts, and increased load on dust removal equipment. Many operators and researchers have claimed that splash formation is the limiting factor in many gas injected processes. The problems listed above lead to loss of production and increased maintenance, adding to the cost of processing base metals. Over the last five years, the GKW CRC has been studying the formation of splash from a number of sources. They include the impingment of drops on liquids[ l·2.31, slopping of bath liquidI4.51, breakup of gas bubbles at the liquid-gas interfacel61, shearing of liquids by gases[7·81, and impact of packets of fluids on solidsl81. Theoretically, the extreme deformation of fluid shape and the influence of surface tension makes the simulation of flow resulting from only a drop impacting on a liquid surface a very challenging computational fluid dynamics problem. Recently, we have been successful in simulating the formation of the Rayleigh jet resulting from a drop impact showing the effect of drop Froude number on the shape of the Rayleigh jet."

Jan 1, 1996

By Shoukun Wei, Cong Wang, Lin Cheng, Zhiyu Qiao, Jingkui Liang, Weidong Zhuang

"The subsolidus phase relations in the Sm2O3-CeO2-CuO ternary system sintered at 1000°C in air have been investigated by X-ray powder diffraction. The system can be divided into two ternary phase regions and three binary phase regions. Solid solution Sm2-xCexCuO4-y is the only ternary phase in the system. The maximum solid solubility was confirmed to be x = 0.2. The crystal structure, oxygen content and superconductivity of the solid solution Sm2-xCexCuO4-y have been investigated.I. INTRODUCTIONAfter the first discovery of the superconducting ceramic system La-Ba -Cu-O[l] with Tc = 30 to 40K, other families of cuprate-based ceramics have been synthesized with higher critical temperature. These oxides include the R-Ba-Cu-O (R: rare earth) systems (Tc=90K or so)[2,3], the Pb-Sr-(R,Ca)-Cu-O systems (T c = 50 to 100K), the Bi-Sr-Ca-Cu-O systems (Tc=80 to 105K)[4], the T1-Ba-Ca-Cu-O systems (Tc=85 to 125K)[5], the Hg-Ba-Ca-Cu-O systems (Tc=90 to 150K)[6,7], and some others. The improvement of Tc is very rapid. The measurement of the Hall and Seebeck coefficients shows that they all are p-type superconductors. In 1989, Tokura et al.[8] discovered the superconductors R2_XCexCU04_y(R = Nd, Pr, Sm) with Tc=20 to 24K (onset) and found that the charge carrier is electron in contrast to their hole doped counterparts. This discovery increases the fundamental understanding of the cuprate-based superconductors by comparing their characteristics and mechanisms to those of the p-type superconductors.One of the outstanding features of these n-type superconductors is the difficulty in obtaining samples in good charactors, such as the difficulty in obtaining zero resistivity state in single crystal or bulk samples; the semi-conductivity of bulk samples in ordinary state (opposite to the superconducting state) and a reducing reaction involved before the superconductivity has been found[9]. Therefore, it is necessary to optimize the sample preparation of the n-type superconductors. All the n-type superconductors have been found· considerable solid solubility. The compositional variations play a governing role in the carrier doping of the superconducting phases. Also, it is vital to the ceramic processing of superconductors to identify the compatible phases in the phase diagram. Finally, there is always the possibility of finding additional compounds, both superconducting and non-superconducting, in an unexplored system."

Jan 1, 1996

By E. Ozberk

The copper and nickel smelting industries are important contributors to the technical and economic well-being of Canada while some of the smelters are among the largest sources of sulphur dioxide emissions in Canada. A review of the operations in six smelters - Falconbridge Limited, Falconbridge, Ontario; Hudson Bay Mining and Smelting Co. Limited, Flin Flon, Manitoba; Inco Limited, Copper Cliff, Ontario and Thompson, Manitoba; Noranda Mines Limited, Horne Division, Noranda, Quebec and Gaspe Mines Division, Murdochville, Quebec - have shown that about 80% of the total sulphur input to these smelters was emitted to the atmosphere in 1980. A simultaneous review of the existing and emerging technologies which can directly or indirectly reduce the sulphur dioxide emissions indicated that it is possible to reduce the emissions to below 20% of the sulphur input to these smelters. This can be achieved by varying degrees of modifications to the smelting operations and installing sulphur fixation facilities at significant costs which may increase the metal production costs. This would consequently make the competitiveness of the Canadian copper and nickel producers more difficult in the already tough world metals market.

Jan 1, 1983

By Qingyu Deng, Shiwei Ma, Guibao Qiu, Hua Wang

"The flow behavior of the blast furnace slag bearing titanium, like viscosity, play an importance role during the iron-making process with the vanadium-titanium magnetite, which is a very special minerals in Panzhihua, China. The dependency of the viscosity on the chemical composition like TiO2, Al2O3, MgO, binary basicity (CaO/SiO2), temperature, reaction time were studied. The experiments showed that the viscosity decreased with the increase of TiO2, MgO content and binary basicity, and it increased with the increase of Al2O3 content and temperature. The viscosity showed a slight decrease within 60mins’ reaction with graphite crucible, however, it increased rapidly afterwards with the formation of Ti(C, N).IntroductionThe ordinary iron ore has been an essential part of raw materials for vanadium-titanium magnetite smelting in Panzhihua to avoid a series of problems, such as slag thickening, adhesive bond of slag and hot metal, etc. The ratio of vanadium-titanium magnetite has been decreased gradually since 1970s, and has down to about 65% now. However, with the substantial appreciation of price of imported ordinary iron ore, Panzhihua Iron and Steel Group aims to increase the ratio of vanadium-titanium magnetite and decrease the dependence on ordinary iron ore in order to lower the cost of smelting process."

Jan 1, 2012

By J. K. Brimacombe

Since the Peirce-Smith converter was introduced to the non-ferrous industry in the early part of this century, there has been a paucity of research on process-engineering aspects of the reactor such as gas injection. This paper reviews studies conducted at UBC over the last decade on gas discharge dynamics, high-pressure injection, bath slopping, oxygen/bath reaction kinetics and out-of-stack heat transfer within the converter. The ultimate objectives of this work have been to extend refractory life and to increase converter productivity.

Jan 1, 1985

By Vinicius Alves Gomes, Jean Igor Margem, Thallis Cordeiro, Frederico Muylaert Margem, Roberto Faria Jr., Sergio Neves Monteiro, Marina Rangel Margem

Natural fibers are attracting the interest of engineering sectors owing to specific advantages such as lightweight and lower cost as well as for their inherent condition of being renewable, biodegradable, recyclable and neutral with respect to CO2 emission. In particular, the fiber extracted from the malva plant stem is nowadays recognized as one of the strongest lignocellulosic fibers. However, the thermal properties of the malva fibers have yet not been fully investigated. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity of a pressed malva fibers sample. The results revealed that these fibers showed a superior thermal insulation capacity.

Jan 1, 2015

By T. Plikas, L. H. Gunnewiek, L. Oshinowo

"Electric furnace smelting is one of the principal unit operations for ferroalloy production, and increased process intensity, improved availability, minimal maintenance and a longer campaign life are common objectives for electric furnace operation in order to obtain favourable economics of production. Furnace designers have continued to develop innovative solutions, e.g., furnace cooling systems, that have allowed these objectives to be realised and CFD modelling plays a key role in the design process. Enhanced understanding of the energy transfer process in the furnace and the ability to develop, evaluate and optimize components of the crucible design to match process requirements are the key motivators for modelling.This paper provides an overview of recent applications of CFD to the design of electric furnaces. The aim is to illustrate what can be done, and identify areas where further work is needed in this field. Examples include furnace bath simulation, crucible cooling system design, taphole design, baking of Soderberg electrodes, off-gas systems, and fume control and building ventilation. It is argued that the trend is for numerical models to become more encompassing while at the same time more accessible, and therefore further improvements in furnace design will be realised with continued and well validated modelling efforts.IntroductionOne of the main processing steps in ferroalloy production is the smelting of ore in electric furnaces. The three-electrode, AC submerged arc furnace is most prevalent method for smelting in the industry, with shielded-arc and DC plasma arc furnaces achieving limited application (1,2). Commercial furnaces range in size from a few megawatts to more than eighty megawatts of supplied power, and operate with the objective of maximising the return on capital invested. Maximising productivity and energy efficiency are two pathways to achieving this objective, through process intensification, increased availability, minimal maintenance, and increased campaign life for the furnace and associated equipment. Concurrently, the need to reduce the environmental impact of metal production by controlling the emission of particulate emissions, greenhouse gases, and other harmful by-products must also be met."

Jan 1, 2004

By Eric Pirard

Theoretical studies carried out on shape analysis supply mathematical tools to analyze the influence of grain shapes on ore beneficiation. In the case of statistic images like those encountered in applied mineralogy parametrical and harmonical analysis methods are used. It is important that the shape parameters are adapted to the specific processes involved in ore beneficiation, while remaining easy to manipulate. The inertia parameters are considered in the scope of granulometric and gravimetric processes It appears that they are able to distinguish between the resulting products where very popular shape parameters are not. The measured statistics are analyzed through discriminant analysis procedures in order to estimate the importance of morphological differentiation and the aptitude of shape parameters to account for this.

Jan 1, 1989

By A. E. Wraith

The tuyère flow rates of Peirce-Smith converters and bath smelting reactors are rendered particularly sensitive to accretion formation, bath depth variations and the general aerodynamic design of the blast delivery system by the limited pressure-flow properties of the conventional single stage centrifugal blower. This sensitivity is examined in terms of tuyère practice, vessel management and fixed engineering parameters for Peirce-Smith converters and the Noranda Reactor by use of the flow resistance factor, R*. New understanding of the effect of accretion growth on the flow behaviour of individual tuyères shows that blowing rates and hence throughputs could be optimised by careful attention to operating detail even within present plant constraints. The concept of the resistance vector is introduced to elucidate comparisons between different practices and to provide reference standards for optimisation. On this basis, the benefits of introducing quite moderate changes in the pressure-flow properties of the blast delivery system are considered. In view of recent developments in the flexible use of converters as hybrid bath smelting vessels for matte production, the foundation is now laid for a searching consideration of relationships between vessel volume and shape, blowing requirements, tuyère performance and production rates, the detail of which will be examined more appropriately in a forthcoming paper.

Jan 1, 1999

By Ivo André

Sorption of copper ions from aqueous solutions by dried biomass of the aquatic plant Potamogeton luscens was studied at laboratory scale. The aquatic plant was collected in water resources in Brazil, washed, dried at 60°C and ground in a bladed mixer. Sorption experiments were conducted in agitated flasks and in a packed bed column. Maximum copper removal was obtained between pH 5.0 and 6.6 when copper was present in the ionic form Cu'. Sorption followed the Langmuir isotherm with saturation attained at 35 mg/g. Free energy of sorption was found, to be of the order of -25 kJ/mol. Sorption kinetics data were better described by a second order reaction and rate constants were calculated in 0.030 1/(min.mg) for - 4.0 mm particles and 0.081 1/(min.mg) for - 0.59 mm particles. Removal of metal ions in a packed bed column showed that Potamogeton luscens biomass can be used in several sorption/dessorption cycles. After sorbent saturation, copper ions can be recovered from the loaded biomass by elution-with H2SO4, solution. Main mechanism responsible for heavy metal uptake was found to be ion exchange. Results are discussed in terms of the surface properties of the biomaterial, solution chemistry of copper ions and thermodynamics parameters.

Jan 1, 1995

By Melinda Channel, Alan W. Weimer, Jonathan R. Scheffe

"There is a need to develop cost effective renewable energy processes for the production of clean fuels that can simultaneously mitigate the U.S. energy/global environmental security issue. If H2 can be obtained cost effectively via the splitting of water using concentrated sunlight, then it’s possible to operate a fuel cell using renewable H2 or to synthesize other fuels based on renewable H2 for generating electricity or for running internal combustion engines. For example, H2 can be reacted with sequestered carbon dioxide (CO2) to produce syngas (H2/CO) via reverse water gas shift (RWGS), i.e. H2 + CO2 ? CO + H2O. The syngas can be catalytically methanated to form synthetic natural gas (SNG) or it can be catalytically reformed to produce liquid fuels such as “green” gasoline via the MTG process (syngas? methanol ? gasoline). The desert SW United States is home to world class sunlight. Fundamental ferrite thermodynamics will be reviewed, an example of the beneficial effect of ferrite surface area on reaction kinetics will shown, and process economics will be investigated for a 100,000 kg/day facility to produce H2.Introduction and Background ThermodynamicsSpinel ferrites of the form MxFe3-xO4, where M generally represents Ni, Zn, Co, Mn, or other transition metals, have been shown to be capable of splitting water according to the two step cycle shown below:MxFe3-xO4 + solar thermal energy ? xMO + (3-x)FeO + 0.5 O2 (1)xMO + (3-x)FeO + H2O ? MxFe3-xO4 + 2H2 (2)This is an inherently clean and sustainable process, as the only net inputs are solar energy and water, and the net outputs are hydrogen and oxygen. Ferrite water splitting cycles are advantages compared to other high temperature water splitting cycles, such as the ZnO/Zn and Mn2O3/MnO cycles, because thermal reduction has been demonstrated at significantly lower temperatures[1, 2]. As a result, overall efficiency may be increased due to the fact that radiation losses increase as the fourth power of temperature, and material considerations for reactor design should be more flexible. Additionally, cycle repeatability has been demonstrated with relative ease as compared to other thermochemical cycles [3-6]. However, the amount of hydrogen per mole that is generated is significantly less than for other high temperature thermochemical cycles due to the fact that only Fe3+ is capable of being reduced at the temperatures of interest[6]. In addition, water oxidation kinetics appear to be very slow, likely due to diffusion or surface area limitations created by near surface oxidation [6, 7]."

Jan 1, 2010

By Wen Chen, Xinghua Liu, Zeyou Peng, Qiulin Wang

"Limonite is a collective for iron hydroxide argillaceous materials. It is very difficult to be treated due to the wide variation in specific gravity and magnetism and the high argillization rate in the course of grinding and beneficiation. The iron ore in Huangmei, Hubei, China is the typical representative of limonite. If the limonite is processed using conventional physical beneficiation methods (e.g. magnetic separation, gravity separation, flocculation-desliming-flotation, or a combined process of the three), it can only be obtained an iron concentrate grade of 51.98% and an iron metal recovery of 86.64%. However, the technique of flash magnetic roasting-magnetic separation can improve the concentrate grade to 61.03%, iron recovery to 91.17%. This paper describes the tests of recovering limonite by flash magnetic roasting in detail.IntroductionLimonite (mFe2O3, nH2O)[1] is a general designation for hydrous iron hydroxides and argillaceous matters. Limonite is hard to be separated because of its complicated geneses, comparatively weak magnetism, nonuniform grain size and being easily slimed during grinding. So most small and medium enterprises sell deslimed limonite product which was dealt with just by simple methods of washing, magnetic separation or gravity separation and so on. In recent years with the iron ore prices soaring, significant progress was made in mineral processing research of limonite. Laboratory research and industrial test results showed that flocculation-desliming-flotation process and roasting-magnetic separation process are the two best methods to recover limonite till now. To compare these two methods, roasting-magnetic separation process is superior to flocculation-desliming-flotation process in aspects of beneficiation indexes and industrial stability."

Jan 1, 2012