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By Jose Hector Figueroa P.

Mexicana de Cananea, S.A de C.V. is a major copper producer mining a large deposit of the disseminated porphyry type considered one of the largest copper resources of the world with 2.7 billion tons of 0.60% copper for the mill plus 4.1 billion tons of averaging 0.26% copper for leaching. Mining of low grade sulfide leach ore, has been an important part of the overall production of the open pit mine which started in 1944. Before this time all the mining in Cananea was by underground methods. The leaching process in Cananea began on the 1920's with in situ operations in the underground mine and small dumps up to the 1950's. Large scale leaching operations began in 1960 and the copper solutions produced were treated in precipitation plants until 1,980 when the first SX/EW Plant was put in operation in Cananea. Leaching action is essentially ferric-bacterial, with no fiesh acid added to the leaching solutions. Traditionally, 5540% copper extraction is recovered fiom ROM, 70- 120 meter high leach dumps in 80 months of leaching. Cananea has successfully improved copper recoveries by implementing several actions that include: 1. Stripping of old dumps. 2. Leaching of old dumps through slotted casing. 3. Crushing conveying leach ore to minus 8 inch and stacking it in 30 meter lifts. As result of these actions, copper recovery has been increased' to about 70% of total copper with actions 1 and 2 and up to 85% in half the time by crushing-conveying the leach ore, based on the same solubility index of the run-of-mine ore. This paper describes the above actions that were implemented to enhance the leaching recoveries from. sulfide leach dumps and the economics of such actions.

Jan 1, 1999

Over the years, numerous hydrometallurgical processes have been proposed as an alternative or complement to smelters for the treatment of copper concentrates. Most of these initiatives met with limited success. Bioleaching is applied commercially for secondary copper minerals heaps and dumps, and bacterial leaching processes are being developed for copper concentrates, although industrial application is still years away. More recently developed processes usually include pressure leaching and/or ultrafine grinding. This paper proposes a new leach process to treat copper sulphide ores or concentrates: the process operates under atmospheric pressure and uses limited concentrations of ferric sulphate as oxidant; the key to the process is the regeneration of the ferric ion, which can be effected in-situ (direct process) or ex-situ (indirect process) using SO2/O2. Examples are presented for the treatment of copper concentrates by agitation leach and of copper ores by heap leaching. Application of the process to copper gold ores and chalcopyrite concentrates is also discussed.

Jan 1, 1999

By T. A. George, David J. Sellmyer

"The concept of achieving a useful high-energy-product magnet through appropriate nanostructuring of known hard and soft phases has been tantalizing researchers since the idea was first proposed. The fabrication of exchange-coupled nanocomposite magnets faces several challenges including aligning the easy anisotropy axes of the hard-phase grains. Here we investigate experimentally two-phase nanostructures of hard Lio-ordered FePt and soft iron-rich/cc Fe(Pt). The Fe-Pt thin films were produced by epitaxial cosputtering onto MgO (001) single-crystal substrates which lead to strong (001) texturing. The measured hysteresis loops indicate nearly ideal exchange coupling. Excellent magnetic properties are obtained, with largest values of coercivity (51 kOe), saturation magnetization (1287 emu/ cm3, J, = 16.2 kG), and nominal maximum energy product (58 MGOe).1. IntroductionA key figure of merit for permanent magnets is the maximum energy product (BH)rrw.x. The achievable maximum energy product is determined by a magnet's saturation magnetization M, and its magnetic anisotropy. For example, it is well known that (BH)rrw.x :S 4n2M,2• In the past, record energy products have been the result of discovering new compounds with high values of magnetization and anisotropy. However, finding new compounds with better magnetic properties than the current record-holding magnet Nd2Fe14B has proven to be difficult. A different approach is to exploit the exchange coupling mechanism between known hard and soft magnetic phases to enhance the maximum energy product [1-5]. In such a composite system, high coercivity is achieved due to the anisotropy of the hard phase as well as a nanostructure which prohibits large-scale domain wall reversal mechanisms. Magnetization is enhanced by the soft phase and loop squareness results from texturing of the hard phase easy-axis as well as complete exchange coupling between the coexisting hard and soft grains."

Jan 1, 2012

By Ruixiang Wang, Jinhui Li, Youjun Xiao, Daoling Xiong, Hao Chen

"Leaching solution prepared from spent battery materials contains large quantities of valuable metals, such as Cu, Ni, Co, Mn and Fe. Therefore, recovery of valuable metals from acidic polymetallic aqueous solutions is of great importance for every plant. In this work, a method is introduced of recovery of Ni, Co and Mn from polymetallic solution prepared by leaching spent battery material. The basic concept includes copper was removed through replacement by iron powder followed by iron precipitation in goethite method. The experimental results show that Cu can be removed 99% at least through replacement by Fe powder, and the removal of Fe can achieve 99% by goethite method. At the same time, the loss of Ni, Co and Mn are about 2%, 3 % and 2%, respectively. The process of differential removal of metals can be selected as the treatment alternative that combines simplicity, efficiency and reliability with low capital and maintenance costs. The purified solution which only contains Ni, Co and Mn can be used to prepare NixCoyMnz ternary system precursor.1 IntroductionNickel and Cobalt are very important metals which are applied in many fields, such as energy material and support material for some new material field. The world demands for such metals is progressively increasing, while raw resources are being depleted and with the constraints raised by the Law and related legislation assigned to protect the environment from hazardous wastes in the world. Nowadays study on reutilization of waste materials has great significance for achieving secondary resources recycling and preventing environmental pollution. There are many hydrometallurgy methods applied for dealing with these wastes, while they usually contain large quantities of valuable metals, such as Cu, Co, Mn and Ni, as well as impurities, such as Fe, Zn, and etc. Therefore, proper treatment of these leaching solutions prior to their discharge is of great importance, so that the contained valuable metals can be recovered.Separation and extraction of metals from leaching solution can use some methods through solvent extraction[l,2], ion exchange[3,4], precipitation with sulfide[ 5] or alkali[ 6] and electrolytic recovery[?]. Among the appropriate treatment alternatives, replacement and differential precipitation is the most attractive treatment that combines simplicity, efficiency and reliability with low capital and maintenance costs."

Jan 1, 2011

By Freddy Syvertsen, Ali Riza Tarakcilar, Engin Tan, Derya Dispinar

"It has been shown that the disturbance of the advancing liquid front in the mould cavity may lead to surface entrained defects known as bifilms. These defects can deteriorate the mechanical properties significantly. The developments in the simulation of castings aid many casters. It is quick and economical. Therefore in this work, the aim was targeted to optimise the mould filling of a tensile test pattern design that is used for aluminium alloys. Several different designs, gatings and runner systems were investigated with Vulcan Casting Simulation Software. In addition to the achievement of non-turbulent and quiescent mould filling; other parameters such as temperature profile, porosity and feeding were investigated to optimise the process.IntroductionConsiderable effort has gone into understanding and controlling defects that are formed in aluminium and its alloys during casting. The conventional approach was the elimination of porosity by eliminating hydrogen in the melt simply due to the following reaction:"

Jan 1, 2012

By G. Haesebroek

In L969 Metallurgie Hoboken-Overpelt started an industrial plant for the separation of iron and zinc from a concentrated CoCL2 solution. Iron and zinc are extracted in column contactors by a solvent containing 12 vol % of tertiary amines in xylene. The extracted metals are stripped from the pregnant organic phase by precipitation with a NaOH solution at pH LL. In this paper an overview is given of the industrial process. In order to overcome some drawbacks of this process (low flash point of the diluent, reagent consumption, batchwise stripping) an alternative solvent extraction process has been examined. In this alternative process, iron and zinc are extracted with an or¬ganic phase containing 50 vol % of TBP in Escaid 110. The pregnant solvent is stripped with water in conventional mixer settlers. Despite the ability of this process to overcome most of the inconveniences due to the use of tertiary amines, it suffers from the poor stability of TBP in concentrated chloride solutions, resulting in unavoidable and inacceptable precipitation phenomena in the stripping section.

Jan 1, 1988

By Chuan-fu Zhang

Li(Nil/3Col/3- xMnl/3)MxO2(M=Ti, Mg) cathode materials were prepared from LiOH?H2O and oxalate precursor. The physical and electrochemical properties were studied by XRD, SEM, cyclic volt-ampere (CV), AC impedance and constant current charge-discharge. The results show that crystal volume of Ti4+ or Mg2+ doped sample is increasing and the electrochemical reaction resistant Rct is decreased at high rate, improving the cyclic performance and rate capability. The effect of Ti4+ doped is better than Mg2+. The sample is well crystallized and simple pure phase with a-NaFeO2 layered structure when doping quantity x=0.025. The second specific discharge capacity of Li(Nil/3Col/3- 0.025Mnl/3)Ti0.025O2 is 143.2mAh/g at 1C,128.0mAh/g at 2C in the voltage of 2.75-4.3V,and still has 140.7mAh/g and 121.7mAh/g after 20 cycles, respectively, keeping 98.25%, 95.07% capacity.

Jan 1, 2009

By C. M. Acuna

Scarcity of high grade copper low impurity content ores is a reality and processing of low grade dirty concentrates is a need. In spite of this fact, innovative strategies have to be looked at to comply with day to day more stringent environmental regulations. From this perspective the production of matte grades over 70% in copper presents several merits, but it must be contrasted with the fractional distribution of impurities reporting to the condensed phases. Converting of white metal high in arsenic content results in moderate fraction of arsenic to gas, but high deportment to blister. Therefore, production of anode copper, as required by the electrolytic refinery, may result in several operational difficulties. Furthermore, by recycling the flue dust and slag produced in the smelting-fire refining cycle, the arsenic content in the feed to smelting increases and so does in the resulting anode copper. The Teniente Converter, as a smelting unity, has probed suitable for production of high matte grade near white metal composition but regarding distribution behaviour of impurities there is lack of reliable data, specially when processing concentrates over 1% in arsenic content. In the new scenario, i.e. low grade copper high arsenic content concentrates, to fully asses the merits of this technology the effect of matte grade, secondary materials recycling and arsenic in feed upon the distribution coefficient of arsenic between slag and matte, mainly, must be evaluated both from a theoretical approach and by use of industrial data. Based on available data correlations of distribution coefficient, matte grade and matte/slag ratios with arsenic in feed and copper content in slag are worked out. Based on these results suggestions as to matte grades facilitating to deal more efficiently with the handling of smelting byproducts are proposed.

Jan 1, 2006

By Bart Blanpain, Muxing Guo, Zhuangzhuang Liu

In order to stabilize free lime in the basic oxygen furnace (BOF) slag to achieve high value products, quartz sand and other additives are injected into slag. However, the current hot stage slag stabilization does not work in case of slag (before treatment) with a liquid fraction lower than 90%, where the slag containing solid particles is too viscous. Therefore, it is essential to understand how solid phases affect the viscosity of the slag system. In this study, the industrial BOF slags were investigated with respect to the correlation between volume fraction of solid phases and its viscosity. Slag viscosity was measured with a rotating type viscometer at temperatures below the liquidus. The volume fraction of solid phases was quantitatively calculated with FactSage. The Einstein-Roscoe equation was employed to predict the viscosity of BOF slag.

Jan 1, 2016

By J. M. Skeaff

As much as 100% of the gold and 67% of the silver in a sulphur-bearing hydrometallurgical leach residue have been transferred to copper metal at copper smelting temperatures by dissolving the partially calcined residue in an iron-bearing slag maintained in equilibrium with the liquid copper metal and matte phases. The precious metals can then be recovered by conventional refining techniques. Copper can be recycled at least four times without any detrimental effects on gold and silver transfers and recoveries. Apparent copper recovery in the .process can be over 100% because of the copper content of the residue. Based on slag analys.es, the overal1 recovery of gold in the copper metal and matte phases varies from 94% to 100% under all conditions investigated. On the? same basis, silver recovery varies .from 9S% ?to 99% under optimum conditions, but is only 4S% to 73% under other, less attractive conditions. Unaccounted for silver losses of' about 30% make it difficult to determine the major factors affecting ?silver transfer and recovery. A method for implementing the technology on a commercial scale at a Canadian copper/zinc smelter has been proposed. A preliminary economic assessment and comparison of the proposed pyrometallurgical process with conventional cyanidation indicates that either process is economically attractive for recovering gold and silver from leach residues. Although the capital costs are higher, the pyrometallurgical process is simpler, has higher recoveries, lower operating costs and no .potential environmental problems related to cyanide disposal.

Jan 1, 1989

By Ailton da Silva Ferreira

Thermoset polymers, like the polyester, become harder with increasing temperature owing to molecular crosslink formation, which is a thermal benefit for composite matrix applications. Natural lignocellulosic fibers, however, have low thermal resistance and tend to degrade with increasing temperature. Therefore, the combination of a lignocellulosic fiber, as reinforcement, with a thermoset polymer, as the matrix, results in a composite material with complex thermal behavior. In the present work, a thermal analysis was conducted on polyester composites with different amounts of curaua fibers. Both TGA and DTG curves were analyzed to determine the effect of the curaua fiber on the thermal resistance of the composites. It was found that the curaua fiber sensibly affects the thermal behavior of the polyester matrix for fiber amounts above 10% in volume. This effect is associated with an increase in thermal degradation.

Jan 1, 2010

By Hiroshi Nakajima, Kotobu Nagai, Toshihiro Hanamura

"Low carbon ferritic steel bars with ultra-fine grain structure was developed through a warm rolling for the first time by the present authors. They show better low temperature toughness than conventionally hot-rolled plates. Hence, the brittle fracture surfaces in Charpy tests were examined in terms of the effective grain size of fracture, compared with those of conventional QT steels. The ductile-to-brittle transition temperatures were in good accordance with those for the QT steels if referred to the effective grain size of fracture: · However, the size was a few times that of the ferrite grain. This means the grain refining is not yet fully utilized from the viewpoint of low temperature toughness. The anisotropy of· the impact properties and the annealing effect of highly dislocated structure on the toughness are also discussed in the present paper.IntroductionFor structural materials, both high strength and good toughness are required. Well-known approaches for obtaining better toughness for steels are as follows:1) Grain refining2) Addition of Ni3) Thin plate effect by cracking parallel to the rolling direction prior to crack propagation4) Contribution of metastable austenite.Among them, only the grain refining can raise the strength and improve the toughness. And it is well known that the finer the ferrite grain size, the lower the ductile-to-brittle transition temperature. For example, in the case of 0.11 carbon steel, the transition temperature decreases linearly to in d 1/2 [1 ]. However, these have been told in the regime of coarse grain size that is larger than 10 µm in diameter. There ~as .been no study dealing with the low temperature toughness in the regime of ultra-fine grain size with a diameter in the order of 1 µm."

Jan 1, 2000

By Jean-Louis Dirion, Guy Depelsenaire, Patrick Sharrock, Souhila Kribi, Ange Nzihou, Jocelyn Ramaroson

"This study assesses the Novosol® process, an emerging technology developed by Solvay to treat heavy metals from dredged sediments using phosphoric acid. The main goal is to convert toxic metal ions, such as Pb2+, Cd2+, Zn2+ and Cu2+ to insoluble metallic phosphates. The effectiveness of the treatment was evaluated by performing the chemical reaction in a tubular reactor, followed by convective drying and maturation of the treated sediment at ambient temperature and finally thermal destruction of the organic matter by calcinations (500°C-700°C). Selected variables (acid concentration, volume fraction of solids, flow rate, drying and calcination temperature and time) were investigated. Laboratory scale experiments were carried out with various combinations of these parameters. The influence of the quantity of acid and the temperature of calcinations on physical properties of the sediment and stabilization of the heavy metals are discussed. Introduction The French territory counts 525 000 km of rivers which transport each year on average 6 million m3 of sediments. Their deposit causes the silting of channels, rivers and lakes. This completely natural phenomenon is exacerbated by the introduction of industrial and urban wastes into the erosion and sedimentation process. This silting leads to clogging of rivers, with a reduction in their flow rates. Consecutively, other problems appear, such as flooding risks, decrease of biological purification capacity and associated loss of the biodiversity. The presence of toxic compounds (from industrial, household or agricultural origins) in the sediments worsens the situation, and requires curing to restore the natural environment and its function. The dredged sediments are either spread on agricultural land, land tipped, confined or sent for chemical or physical treatment [12]. The first research programmes on toxic sediments appeared at the end of the Eighties in the United States, in Canada, in the Netherlands and in Germany. Several techniques of treatment were developed for the sediments; these techniques can be used alone or in combination. These techniques include extraction and concentration of the pollutants: the pollutants are isolated from the sedimentary matrix and the sediment is decontaminated. In some cases of organic contaminations, the pollutants are destroyed by chemical oxidation or biodegradation and in other cases, the contaminated material is either stabilized (mixed with hydraulic binders), or destroyed (incineration) [14,15]. Phytoremediation by afforestation has also been reported [19]."

Jan 1, 2008

By Reza Rahimi, M. Nili Ahmadabadi

"Because of high cost and shortage of primary resources of Ni-base superalloys, revert alloys can be used as a part of charging materials for production of superalloys ingots. The current study is based on recycling of IN738LC, a Ni-base superalloy, using 30% and 50% reverted alloy and balanced amount of virgin raw materials. Therefore, it has been attempted to cast an alloy with references to standard chemical composition and mechanical properties. After charging and casting in vacuum melting furnaces, chemical composition verification and non-destructive tests (i.e. Penetration and Radiography Tests), quality of samples were evaluated at elevated temperature by stress-rupture test. Results acquired from chemical composition and mechanical test indicate that cast ingots using 30% and 50% reverted alloy is reliable and consistent with the quality control requirements.IntroductionIn recent years, there have been many fluctuations in cost and availability of raw materials which are extremely determining in Ni-base superalloys production. Accessibility to the high purity metals such as Cobalt, Molybdenum, Tantalum, Niobium and etc. have been problematical during the past decades. Therefore, shortages of critical raw materials beside the economical considerations motivated the alloy suppliers and investigators to study and find alternate sources such as reclamation and recycling of scraps [1].There are a lot of reasons for the necessity of recycling; perhaps the most justifiable one is that consumers themselves produce scraps. For example, the weight of a finished superalloy product could be less than one-third of the cast alloy weight and in the case of complicated machined parts; this portion may reach to one-tenth [2]. High values of constituents, reduction of energy consumption and environmental concerns have all strengthened the obligation of recycling in Ni-base superalloys.Because of the high degree of risk in usage of improper materials for production of turbine blades, a delicately controlled program for recycling is needed. Depending on the type of scraps, this program can define the recycling procedure, required instruments, allowable percentage of scrap for usage and finally confidence level of the process."

Jan 1, 2012

By Masao Miyake, Eiichiro Matsubara, Tetsuji Hirato, Yasuhiro Awakura

"Zn-Cr alloy coating with around 15 wt% Cr has been found to have much higher chemical corrosion-resistance to steel than conventional zinc plating, while· its structure has not been clarified. The Zn-Cr alloy plating is performed at high current densities around 1 A cm-2 and for 10 to 20 sec using acidic aqueous sulfate solutions with some additives in the iron-steel industry. Due to the high current densities, it seems reasonable to consider that the Zn-Cr alloy plating proceeds under an unsteady-state condition and that the resulting coatings have a non-equilibrium phase and have a structure change in the .direction of thickness. In this research, the crystal structure of the Zn-Cr alloy coating electrodeposited at high current densities and change of the structure in the direction of thickness were examined by X-ray diffraction. The coatings containing under 20 and 35-40 wt% Cr had hcp and bee structure, respectively, while the coatings containing 20-35 wt% Cr comprised two phases with the hcp and the bee structure. The structure of the coating varied in the direction of thickness; both the hcp and bcc phases coexisted in the vicinity of the substrate, while the hcp phase became predominant with increasing distance from the substrate.IntroductionRecently it has been reported that Zn-Cr alloy coating containing around 15 wt% Cr has much higher corrosion-resistance to steel than conventional zinc plating.1-3) The corrosion-resistanc·e of Zn-Cr alloy plated steel sheet with a plating amount of 20 g m·2 is, for example, superior to that of Zn plated steel with a plating amount in the range 60 to 90 g m·2 , which is widely used for automotive bodies today.4l The Zn-Cr alloy plating is obtained by electrodeposition at current densities over 0.5 A cm·2 from a sulfate solution containing zinc and trivalent chromium ions and some additives.5•6) The deposition current densities mentioned above are much higher than those for usual electroplating processes, e.g., Zn, Cu and Ni plating, carried out about 0.05 A cm·2 • Therefore, the time required for plating is very short; around 10-20 sec. Due to the high current densities, it seems reasonable to consider that the· Zn-Cr alloy plating proceeds under an unsteady-state condition and that the resulting coatings do not have a phase expected from equilibrium diagrams; no phase diagram of the Zn-Cr system with a full composition range has been available. 7). In other words, the alloy phase plated would be a non-equilibrium phase with unknown structures."

Jan 1, 2000

By Muhlis Nezihi Saridede, Burak Birol

"Plastic wastes become a huge problem day after day due to the growth of plastic industry. Hence, plastic wastes are used as a raw material for other industries to eliminate this problem. Polyethylene Terephthalate (PET), which is a commonly used for plastic bottles, may be used as a reductant for iron production because of its C and H content. In this study, composite pellets containing iron ore concentrate, flux and reductant were prepared. Crystallized PET bottles and coke were used as reductant after ground. The prepared pellets were reduced at 1400°C for 30 min. and iron nuggets were produced successfully. Usage of waste PET purely as reductant in composite pellets gives a higher metallization degree and proper carbon content than coke or PET and coke mixture.IntroductionPlastics can be seen everywhere, especially at packaging industry in our common life. The increase of plastic usage ends up with an important problem, the increase of plastic wastes. Many studies have been carried out about usage of plastics as reductant in blast furnace such as Ogaki et al.[1], Heo and Baek [2], Saridede [3], Minoru et al.[4], etc. Besides, Kato et al. [5], Nomura and Kato [ 6] and Rongfang et al. [7] have pointed out the use of plastics in coke ovens regarding to its calorific content. In EAF steelmaking, a mixture of coal/coke and plastics can be used as an energy resource instead of only coal or coke. [8] Also, the usage of PET and PC in self-reducing composite pellets increased the reduction rate. [12]PET (Polyethylene terephthalate ), which is commonly used for soft drink plastic bottles, is an important municipal waste due to its C and H content. Its molecular formula is (C10H8O 4)n. Demir and Dincer showed that PET can be crystallized at 250°C to have the ability to be ground to a size of -100 µm. [11]"

Jan 1, 2011

By Huang Chao

The thermodynamics analysis on reducing-matting smelting of sulfide ore of lead, antimony and bismuth which use ferric oxide as sulfur fixed agent is first analyzed. Due to the analysis of reaction mechanism, ferric oxide is first reduced to ferrous oxide, then ferrous oxide produce reducing-matting reaction with sulfide ore and reducing agent as reaction equation: MeS+FeO+CO=Me+FeS+CO2. The reaction thermodynamic calculation shows that the reducing-matting reactions of lead sulfide, antimony sulfide, Jamesonite, and bismuth sulfide are feasible, but is infeasible for zinc sulfide. These conclusion provide a feasible method for solve the pollution which produced in the smelting of sulfide ore of lead, antimony and bismuth.

Jan 1, 2006

By Zhijing Zhang

The management of hazardous wastes is important in a society which is increasingly concerned with environmental issues. Incinerators such as the slagging rotary kiln are widely used in the treatment of hazardous wastes. However, in order to assure a smooth operation of the rotary kiln, the melt should have both a low melting point and high fluidity. In this study, the fluidity of various hazardous waste rotary kiln slags was measured in terms of length of flow using the crucible test technique. It was found that the slags have melting points ranging from 1372 to 1424°C while their fluidities varied from 61-102 mm. The effect of addition of oxides on the fluidity of a slag containing 47 wt% SiO2 was also investigated. For this slag, additions of SiO2 (up to 56 wt%), FeO and Na20 increased fluidity, whereas the addition of CaO and A1203 resulted in lower fluidity values.

Jan 1, 2002

By Antti Roine

Sulfidic zinc concentrates are usually roasted in a fluidized bed furnace into sulfur-free oxide form. Metallic zinc is produced from this oxidic calcine using hydrometallurgical leaching, solution purification and electrowinning stages. The roasting step is necessary because zinc oxides are easier to dissolve using traditional leaching methods than zinc sulfides. The Kokkola Zinc smelter uses various types of zinc concentrates and secondary materials as feed mixture. This makes it difficult to find optimum process parameters for the roaster when the composition and particle size distribution of the feed mixture varies even on a daily basis. Certain conditions may even cause difficult accretion problems or increase the amount of calcine in the process off-gas line excessively. A thermochemical heat and material balance model was developed for process advisor, in order to estimate the effects of different process parameters (temperature, process air coefficient, concentrate feed, oxygen enrichment, water feed, etc.) on the heat balance, roasting temperature and calcine composition. This model was constructed using the heat balance module of HSC Chemistry 4.0 software. The prevailing chemical compounds in the concentrate and calcine were verified using mineralogical analyses and equilibrium calculations. The roasting process seems to operate near chemical equilibrium conditions, if the behavior of the main components is considered. This paper describes briefly the basic principles of the calculation model and outlines the results with several diagrams and discussion. The calculated results were in reasonable agreement with the recent process air oxygen enrichment and water feed test campaigns carried out at Kokkola in 1999.

Jan 1, 2000

By S. Seetharaman

A mathematical model has been developed to evaluate the viscosities of melts at high temperatures. The viscous flow in liquid is described by the equation, {n = Aexp(AG*/RT)} based on the absolute reaction rate theory. The Gibbs energy of activation,{ AG* } is considered to be a function of the temperature as well as the composition of the melt. The model has been applied successfully to various metallic and slag systems from unary to quaternary. On the basis of this model, a relationship has been suggested to relate the Gibbs activation energy of viscosity to the Gibbs energy of mixing in binary metallic melts. The viscosities predicted from available thermodynamic data in the case of a number of binary metallic systems using this correlation show satisfactory agreement with the reported experimental values.

Jan 1, 1994