Search Documents

By J. Boltano

This paper discusses the study, design and implementation of the new gas handling system for the Caletones Smelter of Codelco-Chile. A discussion on design conditions for a future Sulphuric Acid Plant using Teniente Converter gases is also included. The old system which started to be modified in 1985 and relied on natural draft and used balloon flues, resulted in a limited gas handling capacity for operation under future process conditions. This system also caused excessive fugitive gases in the smelter working areas. The new system permits handling of process gases from the higher capacity Teniente Converters Installed in 1987-1989 improving the gas handling of the reverberatory furnaces and Peirce-Smith converters as well as the environmental conditions of the smelter. This system utilises improved converter gas hoods, evaporative cooling and electrostatic precipitators gas cleaning, and is based on natural draft.

Jan 1, 1992

By J. Boitano

This paper discusses the study, design and implementation of the new gas handling system for the Caletones Smelter of Cbdelco..Chile. A discussion on design conditions for a Mure Sulphuric Acid Plant using Teniente Converter.gases.is also included. The old system which started to be modified in 1985 and relied on natural draft and used balloon flues, resulted in a limited .gas handling capacity for operation under Mure process conditions. This system also caused excessive fugitive gases in the smelter working areas. The new system permits handling of process gases from the higher capacity Teniente converters installed in 1987-1989 Improving the gas handling of the reverberatory furnaces and Peirce-Smith converters as well as the environmental conditions of the smelter. This system utilises improved converter gas hoods, evaporative cooling and electrostatic precipitators gas cleaning, and is based on natural draft.

Jan 1, 1992

By M. J. King

The Chino Smelter embarked on a program to reduce smelter emissions. Fugitive sulfur dioxide and particulate emissions were reduced by (i) removing the flash furnace settling chamber and (ii) installing a baghouse, to treat converter secondary emissions. Neutralization plant capacity was increased, to accommodate increased flow from the flash furnace off-gas cleaning system and to reduce costs.

Jan 1, 1998

By Tracie Zoeller, G. Paul Neitzel, Jr. Sanders

"As-cast aluminum alloy microstructures are highly segregated. Coring occurs when solute is rejected during solidification resulting in a non-uniform solute distribution across the dendrite arms. Furthermore, coarse constituent phases are formed in the interdendritic channels as a result of coring. These constituents are either soluble or insoluble and can form from the major solute elements, or the impurity elements iron and silicon. The dissolution of these constituents, or precipitates, is an important consideration in determining the microstructural evolution of an alloy. The properties of an alloy are significantly affected by the morphology of the precipitates. Precipitates can be either beneficial or detrimental to the properties of the alloy. Regardless of the nature of the precipitates present, it is useful to understand the dissolution process. A diffusion-limited dissolution model for planar precipitates is presented and compared to an analytical solution and to models in the literature. Experimental data for the dissolution of AhCu precipitates in a dilute alloy are compared to the proposed model, and found to have good agreement.IntroductionDuring the processing of precipitation hardening alloys, beginning with the solidification step and ending with the final solution heat treatment step, there are a variety of particles that form. Some of these particles must be dissolved and solute redistributed and re-precipitated in a more homogeneous distribution than as it first appears in the as-cast microstructure. The particles can be classified by size as microstructure develops during processing. Coarse particles that form during solidification can either be soluble, partially soluble or insoluble. These particles can be the result of coring of the major solute elements as well as the limited solubility of elements such as iron and silicon. Iron and silicon can combine with the major solute elements such as copper in 2xxx alloys forming coarse phases often referred to as constituents. Figure l(a) shows the as cast microstructure with the constituent phases, Al2Cu and the insoluble phases containing Al-Fe-Mn-Cu-Si [7]. During preheating the soluble phases such as AhCu that were formed by eutectic decomposition must be taken back into solution, whereas the insoluble phases remain essentially unchanged by most thermal operations. Figure l(b) and (c) show some of these constituents after subsequent preheating steps. In Figure l(b), AhCu platelets are shown and in Figure l(c) the remnants of the AhCu phase are noticeable, along with Mn-bearing dispersoid phases. Reduction in the volume fraction and size of these phases improves the ductility and fracture toughness as well as reducing the inhomogeneities that occur during coring. Also adjacent to the dendrite arm boundaries are smaller AhCu phases that precipitate by a solid-state transformation on cooling to room temperature."

Jan 1, 2004

By D. S. Barr

Mineralogical, lithological, and metallurgical studies were conducted on various gold ore deposits currently controlled by Freeport-McMoRan Gold Company. Ore samples were first lithologically and mineralogically categorized, then subjected to chlorination, roasting, and autoclaving pretreatments to determine their effects on gold recovery in a subsequent alkaline cyanide carbon-in-leach extraction. The studies indicate that, while organic carbon and sulfide sulfur are the primary refractory components, their effect on process response must be interpreted with respect to the deposit's geology and mineralogy. This approach has proven to be an effective method for evaluating metallurgical alternatives and fore-casting future mill performance.

Jan 1, 1987

By M. I. Zinigrad

A model of an ideal associated solution is presented. This model takes into account the existence of complexes of various compositions, sizes and geometries and allows calculating thermodynamic properties and phase diagrams of binary alloys. The model has been used formerly to calculate thermodynamic parameters and the position of the liquidus line for binary eutectic systems and also those having a stable compound in the solid phase. In all the cases the model parameters were not adjusted rather estimated from melting temperatures of the components. The recent studies dealt with the influence of arbitrary-stoichiometry associates on the equilibrium thermodynamic properties of liquid alloys. The application of the model to eutectic systems and systems having an unlimited solubility in solid and liquid states close to liquidus has been considered. It was shown that if the difference in melting temperatures of the components was small, different types of fusibility diagrams were possible: eutectic diagrams, cigar-shaped diagrams or diagrams with upper or lower azeotropic points. Peritectic transformations could take place when the difference in melting temperatures of the components was large. The present work is devoted to calculation of phase diagrams and thermodynamic properties of binary systems on the basis of chrome.

Jan 1, 2006

By J. C. Agarwal

Do large-scale projects in mining and smelting start up and achieve expected capacity on schedule? In most cases not. Regardless of worldwide location, company know-how, or financial backing, unforeseen delays occur. A comprehensive CRA study for the World Bank shows that delays are the rule, not the exception, in most mining and smelting projects. When delays are not factored into analysis and planning, financial projections are, literally, not to be believed. Returns on investment will seldom achieve their targeted level because of startup delays. This paper reviews the results of our analysis of startup of new mines, mills, and smelters; provides a detailed discussion of why delays occur in the smelters and refineries; presents the cash flow implications of startup delays; and discusses preventive measures that should be taken to avoid financial shortfalls,

Jan 1, 1983

By M. Patel, G. Djambazov, J. Shrimpton

"Removing zinc by distillation can leave the lead bullion virtually free of zinc and also produces pure zinc crystals. Batch distillation is considered in a hemispherical kettle with water-cooled lid, under high vacuum (50 Pa or less). Sufficient zinc concentration at the evaporating surface is achieved by means of a mechanical stirrer.The numerical model is based on the multi-physics simulation package PHYSICA. The fluid flow module of the code is used to simulate the action of the stirring impeller and to determine the temperature and concentration fields throughout the liquid volume including the evaporating surface. The rate of zinc evaporation and condensation is then modelled using Langmuir's equations. Diffusion of the zinc vapour through the residual air in the vacuum gap is also taken into account.Computed results show that the mixing is sufficient and the rate-limiting step of the process is the surface evaporation driven by the difference of the equilibrium vapour pressure and the actual partial pressure of zinc vapour. However, at higher zinc concentrations, the heat transfer through the growing zinc crystal crust towards the cold steel lid may become the limiting factor because the crystallization front may reach the melting point.The computational model can be very useful in optimising the process within its safe limits.IntroductionLead bullion is commonly refined by removing various impurities (e.g. copper, silver, bismuth, antimony, etc) sequentially. This in normally achieved by the addition of reagents which selectively react with the impurities and the resulting compounds removed by various means. To aid efficient mixing (ensure uniform reactions), batch mixing of materials via the aid of impellers is common practice in a number of industrial sectors. Excess zinc, added during the desilvering process can be removed by one of three methods: (1) Vacuum dezincing - During vacuum dezincing, a vacuum is drawn on the agitated molten lead within a hemispherical vessel (Figure 1). Vaporized zinc condenses on the inner top surface of the vessel. The temperature at which zinc commences to vaporize lowers owing to heating under a vacuum. This enables vaporized zinc to be recovered in the form of high purity crystals without oxidation. The zinc crystals are recovered once the vessel lid is removed and the vacuum is broken. (2) Chlorine dezincing - In chlorine dezincing, molten desilvered lead is reacted with chlorine gas, forming a surface layer of zinc chloride contaminated with small amounts of lead chloride."

Jan 1, 2004

By Satoshi Itoh

Phase equilibria and activities of the components in the liquid lead-antimony-oxygen temary system, which is of fundamental importance for discussing the recovery of lead and antimony from a used lead-battery, have been investigated at 1173 and 1223 K. The two liquid phases of metal and oxide were observed at the temperatures studied, and the tie lines indicating isoactivities were determined. The activities of PbO, Sb015 and Sb203 in the PbO-SbOu and PbO-Sb203 pseudo-binary systems were then obtained by applying the Gibbs-Duhem equation to the phase relation of metal-oxide equilibrium. Both in the pseudo-binary systems the activities exhibit negative deviations from Raoult's law. The vapor pressures of lead, antimony and lead oxide, antimony oxide were calculated by using the activities of the components in the lead-antimony-oxygen ternary system. As a result, an oxidation of antimony concentrated in an anode slime followed by evaporation as antimony oxide Sb406 was found to be considerably effective for the recovery of lead and antimony from a used lead-battery.

Jan 1, 2003

By Zhenfeng Zhou, Qingguo Xue, Jingsong Wang, Yingli Liu, Yuanyuan Zhang, Hailong Huo

Coal burnout strongly depends on the residence time and dispersion of coal particles in the raceway region of a blast furnace. The residence time and dispersion of coal particles are directly related to the lance arrangement. In this work, a three dimensional model was developed to simulate the lance-blowpipe-tuyère-raceway region of a blast furnace. Double lance and eccentric configurations were considered. For the double lance, the double-lance and eccentric double-lance were considered. For the eccentric double lance, the effect of intersection angle of the two lances was investigated.

Mar 1, 2017

By Wei-Tong Du, Yu Wang, Peng-cheng Li, Shu-Chao Wang

CaCO3 thermal decomposition produces CO2 and CaO, and CO2 can be used as a weak oxidant in vanadium extraction. CaO will also affect the vanadium extraction process. This experiment, taking self-blowing and temperature acquisition experiment system, through adding different quality CaCO3, studies the molten iron in the oxidation behavior of C, V and P and its impact, and analysis of CaCO3 decomposition of the heating effect of the molten pool. The result indicates that adding CaCO3 in the vanadium extraction process had no obvious effect on the oxidation of carbon, but partly increased vanadium oxidation which reached more than 90%. Increased CaCO3 additions also increased cooling the molten pool, with a maximum decrease in temperature of 20 K. In addition, the oxidation of P also increased, reaching 40%. The research has proved that CaCO3 can serve to oxidize V and P is effective in vanadium extraction.

Mar 1, 2017

By Wen Liangying, Zou Chong, Tan Xiuqin, Bai Chenguang, Zhang Shengfu

"Eight typical metallurgical byproducts containing iron were selected based on the effect of the chemical composition, particle size, additives on the burnout degree of pulverized coal. Effect of three typical byproducts including fine iron ore, BOF dust and BOF sludge on combustion reactivity and combustion efficiency were investigated using TG-DSC method. The results indicated that the three additives have obvious catalytic effects on pulverized coal. By comparison, the relative active sequence of byproducts to the catalytic combustion can be described as follows: BOF dust>BOF sludge>fine iron ore. Moreover, adding BOF dust as component of additives also shows significant catalytic effects on combustion efficiency during rapid heating process.IntroductionChina is the largest producer in the world with an annual output reaching over 6 billion tons. Solid wastes arising from iron and steel making increases the environment pressure in recently years. For instance, annual output of dust during the production of iron and steel making in China reach up to 5 million tons, which is close to 8%~15% of the amount of steel [1]. Another characteristic of these byproducts is they are finer particle which are just harder to deal with. Since some of solid wastes, including dusts, scales, and sludge, usually contain high iron content, sintering plants have traditionally been used to recycle byproducts in integrated steel plants in China. However these byproducts also have noticeable effects on sinter quality, sinter strength and productivity and, therefore, waste recycling is limited depending on the analysis of the waste materials [2]. Another method which is pre-treatment of byproducts in pelletizing process, increases of energy consumption and production cost. In addition, metallurgical byproducts often contain heavy metals and alkalis. For these reasons, recycling rate of the byproducts in China is very low. Therefore, how to recycle the byproducts in iron and steel making process is an important subject."

Jan 1, 2012

By Yongqi Sun, Zuotai Zhang

Our study investigated the influence of P2O5 and B2O3 on the viscosity and crystallization behavior of Ti-bearing blast furnace (Ti-BF) slags for the purpose of Ti extraction. The investigation of the crystallization behaviors were carried out using a single hot thermocouple technique (SHTT) and the viscosity was obtained by rotating cylinder method. For the viscosity, the results showed that P2O5 substantially increased the slag viscosity. P2O5 is a network-forming oxide, which increased the degree of polymerization of slags and accordingly increased the slag viscosity. However, both of slag viscosity and apparent activation energy for viscous flow remarkably decreased with B2O3 addition. As a typical network forming oxide, B2O3 was introduced into the network and existed dominantly as 2-D structure, BO3 triangular, which caused a simpler structure and a decreasing slag viscosity. As for the crystallization behaviors of Ti-BF slags, both P2O5 and B2O3 enhanced the crystallization trend of rod-shape rutile and suppressed the crystallization trend of dendrite CaTiO3. Therefore the added P2O5 and B2O3 caused the primary phase change from CaTiO3 to rutile. Additionally, it was found that the rod-shape rutile showed a 1-D growth, whereas the dendrite CaTiO3 showed a 3-D growth style.

Jan 1, 2015

By Zhou Jiemin

A mathematical model is developed to determine the economic thicknesses of refractories and insulations in rectangular furnaces, Both the heat loss cost and the lining investment are taken into account to achieve a minimum operation cost. For the sake of calculating the heat flux, the paper is particularly concerned with the simulation of the three-dimensional transient heat conduction processes in the lining and a Douglas-Rachford method is used to solve the finite difference equations, The model has been used to design an industrial electric resistance furnace operated periodically. the values of temperatures and power consumption measured from the furnace correspond with the model results.

Jan 1, 1991

By K. J. Cathro

A hydrometallurgical process is described for the recovery of copper from chalcopyrite concentrates. The process is based on a cupric chloride leach, the concentrate having first been "activated" by heating it with sulphur at a temperature near 400°C. This activation process converts most of the iron of the chalcopyrite to pyrite, which is insoluble in the cupric chloride leachant. The copper is converted to the mineral idaite, which dissolves readily in hot cupric chloride: at 106°C, 98% of the copper is extracted in a three-stage countercurrent leach, the leaching tirqe being 1 hour per stage. The sulphur of the chalcopyrite appears as elemental sulphur, which is recycled for the activation of further concentrate, the final leach residue consisting of pyrite, plus the gangue present in the original concentrate. The copper extracted can be recovered by electrowinning, using a diaphragm cell. Current efficiency (one-electron basis) is about 70% but the cell voltage is only about 1 V, so that power consumption is three times lower than for the conventional sulphate electrowinning process. The leachant is simultaneously regenerated in the anode compartment. The behaviour of minor elements in the concentrate has also been studied.

Jan 1, 1976

By Bingguo Liu, PENG LIU, Haigang Dong, Jinhui Peng, Libo Zhang

Parameters of technique to decarburize from spent petrochemical catalysts via microwave oxidation roasting were investigated. Decarburization process was performed on a microwave heating system. The results showed that the decarburization percentage of spent petrochemical catalysts was significantly affected by roasting temperature and sample thickness in the range studied. The decarburization percentage was 99.5% in microwave fields under the optimized conditions, roasting temperature 600 °C, roasting time 40 min and sample thickness 2 cm respectively. The residuum after microwave decarburization was characterized by field emission scanning electron microscopy (FE-SEM) which showed that the deposit carbon had been removed effectively.

Mar 1, 2017

By V. V. Khristenko, V. I. Dubodelov, V. A. Seredenko, B. A. Kyryyevsky, H. V. Seredenko

"During the last decades investigators of many countries shows an increased interest to alloys which are characterized by miscibility gap in a liquid state. It is connected with essential possibilities of control of structurization in such alloys because of the melt at certain temperature parameters is · emulsion with disperse phase inclusions. These ensure essential influence ·on structurizations.The certain inclusions can play a role of lubrication ensuring ""wearless"" process. The sizes of inclusions of this phase can be rather large proportional to sizes of strengthening phase (up to 1000 nm). Other inclusions ensure process of strengthening of a main material. In this case requests to a dispersibility character of distribution and structure of such inclusions are much higher.The multicomponent alloys of system of copper - (Fe - Cr - C)- alloy concern to the number of advanced compositions. The copper alloys with structure of a type of a ""frozen emulsion"" in which strengthening phase· is a chromium pig-iron are characterized by high thermal stability in the extreme operating conditions. The mechanism of inclusions forming is emulsifying of a melt in miscibility gap at temperatures close to temperature of binodal under superimposition of external effects.The main complexity of producing of ware from such alloys is .a providing in their structure of necessary dispersible inclusions uniformly distributed all over the volume. Thanks to a selective action of electromagnetic fields on liquid phases with various electroconductivity relative velocity of phases is created and is regulated the ratio of their ""apparent"" specific gravity is changed. Excitation of pulsing force effects with the certain frequency on interphase surface allow actively to influence on process of a dispersion of a liquid metal medium."

Jan 1, 2000

By Yuanbo Zhang, Daoyuan Zhang, Youlian Zhou, Guanghui Li, Tao Jiang

"Modified humic acid (MHA) has been developed by Central South University (CSU) and authorized in China. It has been reported that MHA is an effective binder for oxidized pellets prepared from specularite concentrates. In this research, effects of MHA binder on roasting behaviors of the specularite pellets are studied. MHA is an organic binder, containing much carbon, hydrogen, oxygen, etc. During the roasting, MHA can provide some heat because of combustion of hydrocarbon, which is beneficial for the recrystallization of Fe2O3 in the specularite pellets at high temperature. Simultaneously, part of hematite particles within the pellets are firstly reduced to magnetite, then, magnetite is oxidized into secondary hematite, which obviously improves the roasting performance of specularite pellets.IntroductionOxidized pellets have been widely used in steel production as a kind of high quality burden for blast furnace ironmaking [1]. In recent years, production of oxidized pellets is developing very fast. Therefore, the supply of high quality magnetite concentrates, which is the most suitable for pellet production, becomes scarce. It is imperative to pursue new alternative materials for oxidized pellet production [2]. Specularite concentrates have attracted widespread attention due to the advantages of high total Fe grade and low impurity content. However, due to the poor ballability and firing performance, specularite has not yet been widely applied into pellet production [3, 4]."

Jan 1, 2012

By T. J. White

Xtaltite is the trade name for a generic technology which exploits the well known insolubility of some minerals, which naturally incorporate toxic waste elements, to consolidate and immobilise a range of inorganic waste products. It is a specific case of synthetic mineral immobilisation technology (SMITE) which is already used to immobilise high level nuclear wastes (HLW. Although HLW is highly toxic, it exists in relatively small volumes, occurs in central facilities and may be stabilised at low waste loading (< 10 wt%). In contrast, heavy metal wastes are of considerable volume, therefore Xtalitite waste forms must routinely accommodate high waste loadings (usually in excess of 30 wt% for a particular toxic oxide or combination of oxides) and be suitable for fabrication in remote locations using relatively simple technology. This paper details the methodology underlying Xtaltite, with particular emphasis given to the interplay between solid state chemistry, durability and economic considerations. Specific reference is made to the treatment of arsenious and mercurial wastes.

Jan 1, 1994

By A. G. Jackson, Rand R. Biggers, John D. Busbee, Iman Maartense, David P. Lubbers, David C. Liptak

"This paper describes the application of Raman Spectroscopy for characterizing superconducting YBCO thin film parameters. Attenuation of the substrate Raman spectrum as a function of material deposited is established. Also a correlation between film quality and Raman spectrum is explored. The identification and discrimination of superconducting and non-superconducting phases of YBCO is presented. The critical temperature (Tc) of a film as a function of its oxygen content is also established using Raman peak ratios. These results provide significant implications toward the use of Raman Spectroscopy for in situ monitoring and control of the PLD process. Film quality can be controlled via optimization of film oxygen content and reduction of improper YBCO phases. Film thickness can be controlled by monitoring the response of the substrate material. Also the PLD process can be studied and modeled using this powerful observation tool.IntroductionSuperconductors are materials that possess unique characteristics when cooled to sufficiently low temperatures. Below a material's critical temperature (Tc) it exhibits zero resistance to current flow. One such material, yttrium barium copper oxide (YBCO) has a critical temperature of approximately 92° K. Due to its high critical temperature YBCO is being aggressively researched for many possible applications, because of high current carrying capability and strong pinning of flux lines.YBCO in the 123 form is a ceramic material that was discovered in February, 1987. Its unit cell structure is shown in Figure 1 [ 1,2]."

Jan 1, 1997