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By James R. Craig

The General Image Processing System (GIPSY) is being employed for the quantitative textural analysis of complex sulfide ores from the Southern and Central Appalachians and for the determination of liberation characteristics of the mineral constituents during grinding. Optical images from a microscope-mounted TV camera or from 35mm film are converted into digital images which are subsequently analyzed by GIPSY, a transportable image processing software package. Properties measured by GIPSY include spatial distribution of mineral constituents, grain sizes, grain shapes, grain orientation and mineral co-occurrences.

Jan 1, 1982

By Jochen Petersen

Design and operation of heap leach processes are still largely based on,operator experience and rule of thumb. Although considered a low-cost, low-tech route for mineral extraction, the underlying physical, chemical and biological processes are actually rather complex. Numerous heap leach models have been devised over time, but the majority of these tend to simplify the true process and are of limited use in practise. The modelling approach presented here combines the more conventional reaction-diffusion model with models accounting for equilibrium reactions in solution, bacterial growth kinetics, complex reactions schemes, gas flow, heat conservation, etc. One particular model application is discussed in the context of developing a novel high temperature heap leach processes using thermophile micro-organisms. The complexity of processes such as this can only be appreciated with the aid of a systematic model. For the designing engineer an accessible, personal computer based model should be an indispensable tool for the design and optimisation of efficient heap leach operations.

Jan 1, 2002

By G. Mark Aylmore

Various processes have been developed using a combination of elevated temperature and chemical treatment processing to recover Li from silicate minerals. To facilitate further process development, a comprehensive understanding of the deportment of Li and associated minerals in ore bodies is essential to allow the industry to predict the response of ore reserves to metallurgical treatment options. This paper describes results from the integrated use of the John de Laeter Centre’s state of the art analytical and mass spectrometry techniques to characterise a selection of Li bearing ore bodies and determine their amenability to potential processing options for the extraction of Li. The mineralogy, mineral associations, and liberation characteristics of ore-bearing and gangue minerals were characterised using a combination of the TIMA and XRPD studies. The Li content and distribution within minerals were defined using LA-ICPMS and field emission scanning electron microscopy techniques (EBSD, ToF-SIMS) and atomic probe microscopy.

By A. Deneys

An experimental technique has been devised for studying the reaction kinetics of the reaction: ZnO + 2Fe0 = Zn(g) + Fe203, by which zinc evolution can occur from a molten slag bath in the absence of a carbonaceous reductant. When studying the reaction kinetics by heating from room temperature, solid state reactions and poorly defined melting points may obscure the starting point of the reaction. In order to eliminate this problem, an experimental technique was devised whereby two molten slags could be melted independently, and then mixed, to provide a well defined starting point from which to begin taking measurements. Two crucibles were mounted in a vertical reaction cylinder. The upper, mild steel, crucible had a bottom pouring plug which was sealed by a steel stopper rod. A fayalite mixture was contained in this crucible. The lower crucible contained an A12O3-CaO-SiO2-ZnO solution. Once the two slags had been melted, the steel stopper rod was removed from the upper crucible. The upper, reduced slag (fayalite in equilibrium with the upper steel crucible), drained into the lower crucible where the two slags were mixed by submerged argon stirring. Dip samples were taken to measure the zinc content of the final mixture as a function of time. The experimental procedure will be described, as well as results of experiments which were conducted on synthetic slags. The system investigated was similar to the lead blast furnace slag which is produced by the primary lead smelters of Missouri, USA.

Jan 1, 1997

By Zhonglin Ye, Yifeng Shi

"This paper has outlined forms of Au & Ag losses in copper smelting process and methods for increasing Au & Ag recovery, analyzed factors influencing Au & Ag recovery in copper converting process, presented Au & Ag behavior in copper electrorefining process, and reviewed effect of current density/electrolyte circulation rate during electrolysis and surface finish of cathode on Au & Ag losses. Measures and research direction for decreasing Au & Ag losses in electrolysis have also been introduced. Based on Au & Ag behavior in copper electrorefining process and previous studies by others, new approach for increasing Au & Ag recovery in copper smelter has been discussed. And brief comparison has made between continued multiplication method and equilibrium method application in the case of calculation of Au & Ag recovery in copper smelter.IntroductionAs gold and silver are the major by-products from copper smelting process, efficient Au & Ag recovery has become one of the key approaches for copper producers to increase economic efficiency. With similar physicochemical properties, Cu, Au and Ag belong to the first subgroup of elements in the same periodic table. Au and Ag will be enriched into Cu phase firstly when both matte-slag phase and copper-matte phase appear in copper smelting process. However, great changes have taken place in Au & Ag proportions into individual phase due to changes of physicochemical conditions in each smelting process. Metallurgists at home and abroad have carried out a great deal of pilot plant tests and laboratory tests in order to increase Au & Ag the former Soviet Union with regard to Au & Ag losses in copper smelting process in the 1970s and 1980s, and he proposed solutions to increase Au & Ag recovery in copper metallurgical plants. As more than 20 years passed, Jingchun Lu's paper, Discussion on Increasing Au & Ag Recovery in Copper Smelting System, remains as a literature of the most comprehensive study. Based on Jingchun Lu's literature, the authors of this paper discussed new approaches to increase Au & Ag recovery in copper metallurgical plants with combination of many researches done by other researchers for over 20 years."

Jan 1, 2013

By Versiane A. Leão

The adsorption of oleic acid and amine, by Expanded Hydrophobized Vermiculite (EHV) was studied. In appropriate conditions EHV is a good adsorbent for these flotation re-agents and the best results are obtained at situations where the chemicals are at non-dissociated form. The adsorbent shows good chemical stability and may been used in many adsorption-desorption cycles.

Jan 1, 1996

By Hsin H. Huang

Equilibrium calculational software programs can be effectively utilized to model the importance of activity or concentration, solubility, temperature, solution pH, solution potential, and ligand complexation on extraction and recovery processes. Illustrative examples using the calculational program ST ABCAL for the creation of diagrams such as EwpH, activity or concentration-pH, and activity or concentration-EH are presented to demonstrate the fundamental characteristics of real hydrometallurgical mercury dissolution and recovery processes. An industrial application will include leaching of mercury from K 106 mercury sulfide waste and solution purification by iron cementation.

Jan 1, 2003

By Takashi Miyamoto, Hideo Nakae, Hideki Yamaura, Takeshi Yanagihara

"For the production of partially composed metal matrix composites, namely discontinuous MMCs, using a casting· process, the interpenetrated phase composites with SiC particles were fabricated by pressureless iDfiltration using molten Al-Si alloys. This process is based on a wetting phenomenon, therefore, we discussed the technique based on the reactive wetting. The SiC particles coated by diluted water glass were sintered in a mullite Tammann tube and simultaneously infiltrated with molten Al-Si alloys in air at 1173~1573K. As for the improvement of the wettability between the SiC and the liquid aluminum alloy, Fe3O 4 powder was mixed with the water glass due to the thermit reaction between Fe3O4 and molten aluminum alloy. In some experiments, pure aluminum powder was placed on the sintered SiC to increase the interfacial area and the chemical reaction between the sintered Sic. and the melt. By combining these conditions, we succeeded in the complete infiltration without pressure at 1173K.IntroductionAs is well known, the mechanical properties of metal matrix composites (abbreviated MMCs) are superior than that of ordinary metals. However, their use has not been widely accepted because the production cost is very high due to their poor machinability. Therefore, the production of partially composed, namely discontinuous MMCs, by as the Lanxide process [l,2] has been investigated for many years. The Lanxide process, it takes a long time, sometimes up to 10h, in a nitrogen atmosphere for the infiltration. Therefore, the cost will be higher for common use. On the other hand, a high 'pressure process has been adopted for the production of discontinuous MMCs by the Toyota Motor Corp.[3]."

Jan 1, 2000

By E. M. Weenink

A proposed alternative to the conventional zinc extraction processes is the flash reduction of zinc calcines. As part of an overall study of this process, the kinetics of single zinc oxide pellets were investigated. Pellets, compacted from Outokumpu zinc calcine (60.9% zinc, 9.6% iron), were suspended in a flow of CO/CO, mixtures and reduced at temperatures between 1000 and 1200°C and atmospheric pressure. The pellet weight loss with time was recorded and analyzed. It was found that the reduction of calcine pellets (0.9 cm height and 1.36 cm diameter) was controlled by chemical reaction. This paper includes an analysis of the experimental results of two previous investigations of ZnO reduction.

Jan 1, 1992

By Wenya Du, Qingbo Yu, Peng Li, Qin Qin

"A new heat recovery system is proposed. This system uses the endothermic heat of gasification reaction instead of sensible heat to recover the energy of molten blast furnace slag. The gasification technological parameter in molten blast furnace was calculated and the exergy of the system was analyzed. The gasification reactions were studied kinetically by the isothermal thermogravimetry using STA409PC thermal analyzer. The results showed that, according to different gasification agent, this system can produce syngas with different C-H ratio. The exergy efficiency of this system is high and its internal exergy loss rate is about 11%. This method can bring huge economic and environmental benefits which are important to the survival and sustainable development of iron-steel enterprises. The molten BF slag acts as not only thermal media but also good catalyst. The kinetic parameters on gasification reaction with different types of coal used differ from each other.IntroductionEnergy consumption in the iron-making process is about 50%~60% of the total energy input. The blast furnace is very important in the iron & steel process. So energy conservation and emission reduction about blast furnace is very important. In recent years, in order to recovery energy, many new technologies such as TRT (Top gas pressure Recovery Turbine) and CCPP (Combined Cycle Power Plant) were used in iron-making. But the energy of molten blast furnace (BF) slag has only been used limitedly so far.Molten BF (Blast Furnace) slag is the byproduct of iron-making at the high temperatures range from 1723 to 1923K, and has a large amount of sensible heat remaining. The yield of molten BF slag is about 300 kg per ton of pig iron. In conventional processes, molten BF slag is quenched rapidly using a large amount of water to produce a glassy-granulated slag. The quenching slag must be dried before it can be used in cement manufacture. During the process, a large amount of water was consumed and the energy of molten slag can not be recovered. At the same time, it causes environmental pollution problems. So the critical problems of the process are not only energy recovery of molten slag and reducing emission of H2S and SO2, but also guaranteeing the subsequent use value of slag. For this propose, many new technologies were investigated to recover the thermal energy of molten slag. The promising methods are dry granulation [1-4] and reforming of methane [5-9]. The method, utilization of reaction heat instead of latent heat and sensible heat, is quite attractive from viewpoints of energy storage without heat loss, and makes a connection to other industry. But both of them are in laboratory. In this paper, coal gasification in molten BF slag was used to recover the energy of molten BF slag. The gasification technological parameter in molten BF was calculated and the exergy of the system was analyzed. The gasification reactions were studied kinetically by the isothermal thermogravimetry using STA409PC thermal analyzer."

Jan 1, 2011

By James W. Reeves

DuPont was the titanium metal pioneer who put the greatest effort into both R&D and commercial sponge and powder metallurgy production. This was concentrated in the period 1945 through 1963. The commercial results were development of the chloride process for TiCl4 using ilmenite, development and improvement of the Kroll process, development of a modified Hunter process to make titanium powder and commercial development of a direct powder process. The powder metallurgical process failed because of the inability to meet powder chloride specifications. All this work remained a trade secret until published in NMAB -392 by Mahla in 1983. There were other processes explored by DuPont, both improved sponge and powder processes. Much of this work has been continued by others but none, as of yet, resulting in new improved titanium metal capacity.

Jan 1, 2001

By R. M. Sweetin

Detailed descriptions by operating area of the Kidd copper smelter are presented, together with accounts of complement staffing, training, and preparation activities for smelter start-up in June 1981. Concentrate tonnages smelted in the first twelve months of operation were constrained by the capacity of the furnace off-gas system. However, modifications designed and introduced over that period, plus sustained efforts by operations and maintenance personnel have resulted in stepwise improvements in smelter performance.. Consistent operation at design feed rates has been well demonstrated over the third and fourth smelter campaigns and efforts continue on further improving the continuous smelter on-line times and increasing campaign life. In November 1982., following a seventeen month preproduction period, the Kidd smelter attained full operating status.

Jan 1, 1983

By Godwin Beene

During recent years, copper and acid production from Nkana Smelter has formed a significant proportion of ZCCM's total output, but a number of problems affecting the smelter over the last decade have only been recently overcome. This paper discusses recent developments in the smelting practice, highlighting some of the operational problems experienced and associated solutions. The smelter performance over the decade is discussed and the innovations in the smelting technology employed to sustain production in the wake of limited re-capitalization are dealt with in detail.

Jan 1, 1999

By Frederick T. Wallenberger

"Laser assisted chemical vapor deposition (LCVD) is a new containerless fiber process whereby growth of small diameter fibers or microstructures (microsprings, microsolenoids) occurs directly from the vapor phase. The laser beam has a focal point adjusted to coincide with the tip of the growing fiber inside the reaction chamber. Since the growing fiber is not in contact with reactor walls or foreign materials, it is chemically pure, and suitable for optical uses and uses requiring high structural uniformity. Continuous fibers and multifilament yams are possible. The use -of high reaction chamber pressures (1-10 bar) and a small wavelength Nd-YAG laser made it possible to fabricate small diameter fibers at growth rates >1 mm/s. This paper describes the synthesis of single crystal, polycrystalline and amorphous fibers by LCVD, and provides a comprehensive analysis of phase transformations occurring during their fabrication.IntroductionLaser assisted chemical vapor deposition (LCVD) is a new containerless fiber process [1-10] whereby growth of small diameter fibers or microstructures occurs directly from the vapor phase. The laser beam has a focal point adjusted to coincide with the tip of the growing fiber in the reaction chamber (Figure 1). The diameter of the growing fiber corresponds to that of the laser focus. Depending primarily on the laser energy (Le., the temperature at the growing fiber tip), it is possible to obtain single crystal, poly crystalline or amorphous fibers by this method.Since the growing fiber is not in contact with reactor walls or foreign materials, it is chemically pure, and suitable for optical uses and uses requiring high structural uniformity. Laser assisted CVD is a potentially continuous process; continuous fibers and multifilament yams are possible."

Jan 1, 1994

By Kumar P. Dharmasena, Haydn N. G. Wadley, Bill W. Choi

"Non-contact eddy current sensing methods have been developed and applied to Cd0.955Zn0.045Te crystal growth to obtain a better understanding of the melt, solid nucleation, and the growth process. The application of this sensor approach relies on a large difference in liquid and solid electrical conductivities near the melting point and requires knowledge of the relationships between the electrical conductivity, melt composition, and temperature. Using a multifrequency encircling eddy current sensor, the electrical conductivities of three different Cd1-xZnxTe (x=0.00, 0.045, and 0.08) alloys were measured as a function of temperature in a laboratory-scale vertical Bridgman furnace. The measured solid and liquid electrical conductivities were then used in electromagnetic finite element models to analyze the multifrequency responses of eddy current sensor designs during the simulated growth of a crystal. These eddy current sensors were fabricated and installed in a vertical Bridgman furnace and used to monitor many Cd0.955Zn0.045 Te growth runs. One sensor was placed in the vicinity of the ampoule tip to detect undercooling/spontaneous nucleation and two other sensors (""absolute"" and ""differential"" designs) placed to monitor the movement/curvature of the liquid-solid interface during crystal growth. The sensor data was used to characterize the initial melt state, detect the onset of nucle-ation, determine the growth velocity, and identify the shape of the interface.IntroductionSingle crystal CdTe and its solid solution Cd1-xZnxTe alloys (0.03<x<0.05) are used as infrared transparent substrates for infrared focal plane array (IRFPA) detectors [1-6] and as solid state y- ray detectors [7-9j. Cd1-xZnxTe substrates are normally ""mined"" from large polycrystalline boules grown by the unseeded directional solidification of Cd1-xZnxTe melts using either a vertical or horizontal Bridgman process [10-14]. The vertical Bridgman method is particularly popular for growing CdTe and its related compounds. In this process, a Cd1-xZnxTe ingot is produced by first melting a charge in the hot zone of the furnace and then vertically translating the furnace (with its associated axial temperature profile) relative to the stationary crucible to cause directional solidification. In spite of many experimental efforts to investigate the relationships between material purity, stoichiometry, the controllable growth parameters (furnace temperature profiles, ampoule geometries/materials, furnace translation rates and starting position) and the resulting material characteristics (grain structure, dislocation densities, IR transmission, macro-segregation etc.), the yield of Cd1-xZnxTe of a quality suitable for large area (e.g. 4 cm x 6 cm) substrates remains low (<10%). Since much of this poor yield is directly associated with the crystal growth process (e.g. melt stoichiometry, solidification velocity, interface shape, temperature gradients, cooling rate, etc.) intensive efforts are under way to improve this technology."

Jan 1, 1997

By Cajsa Samuelsson, Theo Lehner

Converting and refining play a central role in the extraction of metals. Sweden has a long tradition as an experimental play ground for metallurgists, chemists and alchemists, developing new methods and technologies. Presenters of papers are usually happy in recording successful developments. But reporting failures can be as great a value as the former. In the paper experiments and experience in process development are illustrated, differences between ferrous and non-ferrous developments are highlighted and industrial learning curves are discussed. 53

Jan 1, 2009

By Brian P. Atkin

The NISOMI-81 opaque mineral searcil and identification system uses quantitative color values (Pe, dA, y) and VHN as its determinative para-meters. The system is designed to operate on a Radio-Shack TRS-80 micro-computer which is interfaced to a motorised diffraction grating mono-chromator (WILSCAN). Using an interfaced monochromator/photometer combination a typical identification including the measurement of the photometer data on both specimen and standard, calculation of color values and a computer search takes about 6 minutes. The data file contains 240 minerals at present but can easily be expanded as reliable new data become available.

Jan 1, 1982

By Guohua Bai, Lin Zhang, Shan He, Xuling Chen, Min Gan, Xiaohui Fan, Yanbin Tang

"For reducing the dust content in flue gas during copper smelting in the Ausmelt, technologies and mechanism of strengthening the pelletizing of copper concentrate were studied. The results show that adding bentonite, organic binder or composite binder can effectively enhance the strength of green pellet and reduce the rate of shedding powder in drying process, and composite binder works best. When adding 1 % of composite binder, the drop strength of green pellet increased from 1.9 times/P to 4.5 times/P, the rate of damage dropping from 2 m reduced from 50.12% to 13.08% and the rate of shedding powder reduced from 60.28% to 25.13% at drying temperature of 400111. In addition, the mechanism of binder absorbed in the surface of mineral was investigated by infrared spectroscopy. The results showed that composite binder absorbed in the surface of copper concentrate was in the form of chemisorptions, which made hydrophilic enhanced, while bentonite absorbed in the surface of copper concentrate was physisorption.IntroductionWith the technologies of copper smelting developing, the equipment of copper smelting steps into a large-scale and efficient level in recent years. As Ausmelt smelting is characterized by being efficient, environmentally-friendly and energy-saving, it is generally recognized by the enterprises of copper smelting [l]. The process of Ausmelt smelting starts with materials mixing, and then pelletizing. From this point onwards, pelletized balls are charged to the top of the furnace, undergoing drying and smelting reaction[2]. Since copper concentrate is fine-grained, directly adding into smelting furnace can make it blown out of the furnace together with the airflow upwards, rendering flue gas high in flue dust, which can cause the loss of concentrate greatly, and make smelting environment poor as well. The concentrate transported into the furnace and smelted after disc balling is conducive to improve the capacity of melting furnace during copper concentrate smelting, reduce the powder shedding rate and improve enterprise benefits."

Jan 1, 2013

By M. El Ganaoui, P. Bontoux

"A computational model to investigate solid/liquid phase change transitions for binary alloy under directional solidification is presented. Conservation equations are developed by using an homogeneous formulation. A second order accuracy method of time and space based on finite volume approximation has been evaluated by comparing results to spectral solution for time-dependent solutal convection developping in a melted alloy. For extended model to solid/liquid interface effects time amplification of solutal perturbation injected near the interface is described before considering solutal convection is melt.IntroductionThe enthalpy method gives a front fixing approach for energy equation without introducing coordinate transformation. The interfare position is recovered a posteriori [1]. A number of authors have extended this approach so as to include the convection phenomena within the two phase 'mushy region' [2, 3, 4, 5, 6].We have developed a time-dependent enthalpy-porosity formulation for directional solidification [4, 6, 8]. The interaction between solid and liquid phases is modelised by a Darcien type force in the phase change area. The behaviour of the melt is similar with the flow of an incompressible fluid in a porous medium. This force is proportional to the relative phase velocity. It corresponds to a damping force depending on the anisotropic permeability of the 'mushy zone'. The permeability depends on the liquid fraction and on the size of·solidification microstructures. An informative discussion of a new slant on the general approach of continuum mechanics needed to analyze the formation of mushy zone is given in [12]. The method is extended to the presence of species diffusion: the solutal Stefan condition which expresses the solute incorporation or rejection across the interface is accounted implicitly in a species equation valid in all the domain [14, 15]."

Jan 1, 2001

By Richard D. Hagni

Quantitative techniques have become increasingly important in recent years in the study of ore minerals. Precise measurement of indentation hardness and reflectance is the most important quantitative ore microscopic technique for mineral identification. Reflectance measurements of various wave lengths under monochromatic light provide the data necessary for the preparation of spectral reflectance curves and for the quantitative determination of an ore mineral&apos;s color. The procedures for the measurement of indentation hardness, reflectance, and color coordinates have recently been standardized and 204 items of quantitative data for ore minerals are now available in the first issue of the quantitative data file of the International Mineralogical Association&apos;s Commission on Ore Microscopy. A number of systems utilizing these quantitative data for systematic ore mineral identification have been published and others are in preparation. Rotation properties, although not included on the data cards, are useful in the identification of certain groups of minerals. Other aspects of quantitative ore microscopic techniques include the utilization of automatic image analysis for mineral percentage determinations and the use o~ various microbeam instruments for elemental analyses. These techniques provide a greatly improved basis for mineral identification in mineralogical and beneficiation studies.

Jan 1, 1981