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By H. L. Fraser

A review of the possibilities of performing microchemical analysis in thin sections using a combination of scanning transmission electron microscopy and energy dispersive spectroscopy of x-rays is given. Particular attention is paid to the factors that limit accurate analysis at the highest spatial resolution. As an example of the use of these techniques applied to a potential problem in minerals processing, the identification of iron pyrite and pyrrhotite particles in Illinois, Herrin #6 coal is presented.

Jan 1, 1981

By Stephen Gale, David Clarry, Edmund Smith, Jon Feldman

"In 2006, a Canadian steel maker embarked on an ambitious initiative to become “Best in Class in Energy Management”. This initiative provides the framework for this paper, with some augmentation from other energy management projects carried out by Hatch. The initiative focused on identifying energy/GHG management improvements leading to low-cost implementation of energy savings or GHG emission reduction. The key components of the approach were:• Review site energy management practices and benchmark internationally.• Review best technical practices and benchmark against public energy intensity data.• Conducted a site-wide Energy Assessment and physical review of operating areas.• Facilitation of on site-workshops with staff to prioritize savings opportunities, as well as identify and remove implementation barriers.• Development of an Energy Management Action Plan for implementation of improvements.Most organizations can produce, with relative ease, a list of ideas for saving energy, implementing them is the challenge. This paper addresses these issues as well as the profitability of the energy efficiency improvements and the consequences for GHG emissions.IntroductionWhen one of the authors was an undergraduate engineering student at the University of Cape Town in South Africa, the technical drawing instructor made a statement that was both humorous, and mildly profound. He claimed that the most successful engineer is one who is both lazy and diligent. Lazy, in the sense that the engineer is constantly on the lookout for an easier, more efficient, way to do something. Diligent, in the sense that the engineer will work tirelessly to come up with a good technical solution for the easier way. This paper, somewhat of an anomaly in a compilation of technical proceedings, hopes to break the mould a little, and to show a “lazy-diligent” way of reducing the carbon emissions from an industrial facility, using a steel plant as an example."

Jan 1, 2008

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 D. W. Collins

The uptake of gold from halide solutions by activated carbon has been investigated using various techniques. Halide systems typically exhibit combined adsorption-reduction type behavior. In an attempt to gain more information about the nature of these processes, samples of synthetic highly-oriented pyrolytic graphite (HOPG) were contacted with aqueous solutions of gold-iodide. HOPG represents a model structure for activated carbon comprising of basal- plane sites, edge sites, and various defect sites. Two basic instrumental methods were used to examine the uptake of gold by HOPG. The first was standard X-ray photoelectron spectroscopy (XPS). The other involved several scanning probe techniques. XPS clearly indicated a preferred uptake of gold at edge sites. However, iodine appeared to be distributed on both basal-plane and edge sites. At low iodine additions, tapping mode AFM showed that clusters were concentrated along steps and surface defects. At high iodine concentrations, the HOPG surface was uniformly covered by iodine.

Jan 1, 1998

By J. B. W. Bailey

The Noranda Horne smelter in Quebec, Canada has change considerably during the last two decades to accommodate varying custom concentrate receipts, closure of the Horne mine, better working conditions, environmental programmes, new technology and increased energy and labour costs. This paper highlights the reasons for changing the smelter from two calcine charged and one wet charge reverberatory furnaces fired by coal to a smelter using. tonnage oxygen oil, natural gas and coal in a single wet charged reverberatory furnace and a Noranda Process continuous Reactor. The current operation 1 described, including three major topics; the use of oxygen/fuel burners on the charge banks of the reverberatory furnace which has increase the smelting rate from 680 to 1100 tonnes of concentrate per day; the oxygen enrichment of the Noranda Process converting air to achieve smelting rates of over 1800 tonnes of concentrate per day; the converting of the mixture of 73 percent copper matte produced from the Noranda Process and the 33 percent copper matte produced from the reverberatory furnace.

Jan 1, 1983

By C. Gasparrini

Mineralogy may be applied to the selection of appropriate separation techniques, as well as to assist in the evaluation of problems causing loss of metals and other economically important elements during plant processing. Mineralogic studies may thus help develop techniques to optimize metal recoveries. The present paper describes how such factors as the minerals in which the elements of interest are concentrated, their chemistry, the chemistry of the associated minerals, grain size and textural associations with other minerals in the ore, may affect decisions on separation techniques for the recovery of economic elements. A number of case studies are described in which the mineralogical observation of ore samples has revealed the cause of problems experienced in the extraction of select precious and base metals, or has been decisive in the choice of appropriate techniques for recovery.

Jan 1, 1981

By Dajian Wang

To obtain the thermodynamic properties of a multicomponent liquid alloy system over the whole range of concentration at an arbitrary temperature, the free volume cell theory has been applied to derive the formula of activity coefficients of liquid solutions based on the infinitely dilute solutions at some temperature. The linear logarithmic relationship between activity coefficients of binary dilute solutions and reciprocal of absolute temperature have been verified, and are in good agreement with the experimental values from the literature. The Monte-Carlo algorithm was used to calculate the nonlinear end value equations of binary systems, then the free volume parameters obtained were correlated with the activity coefficients of liquid binary, ternary, and quaternary systems at an arbitrary temperature. Three dimensional a-X-T diagrams of some binary systems representing the temperature and concentration dependence of activities were plotted. The calculated results regarding non-ferrous alloy systems have been statistically examined with the experimental values from the literature. Hence, this simple approach could be useful for analyzing thermodynamic properties of liquid alloy systems.

Jan 1, 2000

By Shantaliu S. Shevade, Muhammad M. Rahman

"This paper presents a systematic analysis of fluid flow and heat transfer processes during the magnetic heating of the substrate material. Heat is generated in the substrate material when a magnetic field is imposed due to change in orientation of the molecules. As a result, the substrate temperature rises. The i;tudy considered microchannels with rectangular and square cross section with heat generation in the substrate due to imposed magnetic field. The results computed were for Gadolinium substrate and water as the working fluid. The purpose of this study is to explore the transient heat transfer coefficient when the fluid is circulated through the substrate via microchannels. Equations governing the conservation of mass, momentum, and energy were solved in the fluid region. In the solid region, heat conduction was solved. From the simulation results, plots of Nusselt number and heat transfer coefficient were obtained over the length of the channel. A thorough investigation for velocity and temperature distributions was performed by varying channel aspect ratio, Reynolds number, and heat generation rate in the channel. It was found that the peripheral average heat transfer coefficient and Nusselt number is larger near the entrance and decreases downstream because of the development of the thermal boundary layer. With the increase in Reynolds number, the outlet temperature decreased and the average heat transfer coefficient increased.IntroductionMagnetocaloric effect (MCE) is the heating or cooling of the magnetic materials due to varying magnetic field. The effect was originally discovered by Warburg. Magnetocaloric materials store heat energy in the way the atoms vibrate and in the way electrons spin within each atom. More heat energy increases the vibrations and also makes the spins more random. When a strong magnetic field is applied to a magnetic material, the magnetic moments of its atoms become aligned making the system more ordered. The more ordered material has lower entropy and compensates for the loss by heating up. When the magnetic field is removed, the magnetic moments return to their random directions, entropy increases and the material cools. Gadolinium is a magnetic material that exhibits high temperature rise during adiabatic magnetization around its transition temperature of 295 K. It has been experimentally observed that adiabatic temperature rise increases with magnetic field strength and can be as high 20 K when a magnetic field of IO T is applied. Thus magnetic field, when applied to a microchannel heat exchanger, causes temperature change in the magnetic material. The fluid flowing through the channel gets cooled or heated due to this adiabatic temperature change."

Jan 1, 2004

By Akio Ohta

The Hyuga smelter has been producing ferronickel by a rotary kiln-electric furnace process in Miyazaki, Japan. Several approaches to improve our operation have decreased the electrical energy consumption. A new process was developed to decrease the cost of energy even further. Oil and technical oxygen are injected through lances to heat up the calcined ores (calcine) instead of the electric power. Main problems during the development of the process were the short life of the water-cooled lances, the check on security of the safety system and the eruption of combustion gases through the calcine bed. These problems have now been overcome successfully, and stable operation can be maintained. The addition of 1 Litre of heavy oil per tonne of ore can save the electrical energy requirement by 8.6 kwh per tonne of ore. The new process has resulted in a reduction of the electrical energy consumption by more than 10 percent

Jan 1, 1992

By Fujio Ishii

The deoxidation of liquid nickel and nickel binary alloys with silicon has been determined at temperatures between 1500°C and 1650°C using quartz crucibles in order to investigate the deoxidation of nickel based alloys. The equilibrium constant of the deoxidation reaction in liquid nickel and the effects of the different alloying elements such as chromium, molybdenum, tungsten, iron, cobalt and coppcr on the activity coefficient of oxygen in liquid nickel have been established.

Jan 1, 1993

By Toru H. Okabe

As part of a systematic study on the thermodynamic properties of complex nitrides, phase equilibria of the system Li-M-N (M Mg, AI, Ga) at 900 K were investigated. An attempt to determine the thermodynamic properties of complex nitrides was made by using the galvanic cell method, which utilizes LiMgN as an electrolyte under nitrogen atmosphere. The electromotive force (Emf) of the cell at temperatures between 800 and 1100 K was measured. While the Emf of the cell at 900 K was measured to be 0.137 V, data discrepancies of ±0.03 V were found. It was difficult to determine temperature dependence of the Emf. The Gibbs energy change for the reaction, 113 Li3N (s) + 1/3 Mg3N2 (s) = LiMgN (s), at 900 K was determined to be !'J.Go, (LiMgN) = -13.2 (±2.9) kJ/mol. Using thermodynamic information on the binary nitride from literature, the standard Gibbs energy of LiMgN was derived to be !'J.Go f (LiMgN)= - 121 kJ at 900 K. The thermodynamic stability range of nitride was discussed by constructing isothermal chemical potential diagrams that provide a better understanding of the stability region of the LiMgN phase. The diagram was found to be in good agreement with the isothermal phase diagram determined by the alloy equilibration method. Although the obtained data includes large uncertainties, the results provide a better understanding of the thermodynamic stability of nitrides. The potential application of this complex nitride to nitrogen chemical sensors or a medium for controlling nitrogen potential is also shown.

Jan 1, 2003

By W. L. Dalmijn, J. M. Krowinkel

A recycling concept of end-of-life televisions starting with shredding will produce a complex material mixture, very heterogeneous in size, shape and degree of liberation. Basically all materials in television scrap are valuable, which means that recovery is important for either economic, environmental or sustainability reasons. However glass, plastics and metals are the materials with the highest potential for recovery. Non-magnetic materials from shredded television sets can be separated into three characteristic size fractions that need further separation for a high value-added recycling of the materials. This study investigated the potential of physical separation of these size fractions into valuable material streams using polyseparator, tlrldy current separator, dry and wet shaking tables and electrostatic separator. An overall mass balance of the mechanically processed televisions was calculated. Evaluation of the produced material fractions showed that heterogeneity in particle shape and size together with the presence of unliberated materials caused sever difficulties in separation when exclusively based on mechanical techniques. The results indicate that a certain degree of dismantling is necessary to achieve products of appropriate quality in physical separation. In order to improve recycling of electronic scrap through design for recycling cooperation between the electronics industry, the manufacturers and the recyclers of electronic goods is necessary.

Jan 1, 2000

By Brian Balmforth

Solvent extraction has been applied successfully to the recovery of a range of metals from a variety of process streams. Particular benefits are derived from the use of new highly selective extractants. These will be exemplified by case studies including the recovery of zinc from sulfate and chloride media using ZENECA's new extractants which show a very high selectivity over iron and the recovery of antimony and bismuth from copper refinery electrolytes using ZENECA's strong and selective extractant DS5834. The conclusions are drawn that solvent extraction is a cost effective technology for metal recovery and recycling, even when used to treat relatively small volume/low concentration process streams, and that it can provide the essential enabling components of a larger system for waste minimisation programmes.

Jan 1, 1996

By S. Neven

The smelting of copper anode slimes, a material which contains mostly lead, silver, copper and selenium, has been practiced for many years with a view to recovering the silver and associated small amounts of gold. However, a theoretical understanding of the process has been lacking and this handicaps efforts to improve and intensify smelting operations. In the past few years work has been done in this area and this work will be reviewed in the paper. The underlying thermodynamics of the oxidation of silver-copper selenide mattes has been developed and used as a basis for the construction of a computational thermodynamics model which attempts to predict the composition of all condensed phases during the course of smelting. The model will be outlined and its successes in matching experimental data, as well as its current deficiencies, will be considered. Supporting work on the thermodynamics of silver solubility in slags, on activity-composition relationships in the Ag-Se system and work in progress on the oxidation state of copper in the slags will be reviewed. These projects are designed to provide further detailed data which will improve the robustness of the thermodynamic model.

Jan 1, 1999

By R. Hurman Eric

The flow of molten slag and matte and the estimation of the mass of settled matte in electric furnaces is discussed and the action of the electric furnace as a settler is considered. Particle size of the concentrate and its grade are major contributors to settler dimensions. Discussion on the production capacity of the electric furnace with reference to operating current, power input, furnace dimensions such as width and length and electrode diameter are given. These discussions are based on considerations derived mainly from experimentally determined properties of the slag such as its resistivity, viscosity and liquidus temperature. Extension of the design and operating considerations to circular furnace symmetry is also discussed.

Jan 1, 1995

By D. W. Hoey

Eight years use of the ISA Process is reviewed and current design and operations described. Nodern Technology used for impurity control and disposal as well as the use of mechanised electrode handling equipment, cell voltage monitoring, cell insulation and an efficient contact bar system are described. Improvements achieved in terms of energy usage and plant productivity are detailed.

Jan 1, 1987

By O. Norman Lotter

The formulation and use of mixed collector suites in sulphide flotation can be traced back as far as 1957 with the work of Glembottskii and his co-workers in Moscow. The subject was reviewed by Lotter and Bradshaw in 2010, and proposed a synergy between ideally-selected different reagent types to deliver improved performance, in particular the in situ catalysis of a xanthate to dixanthogen by a dithiocarbamate. Correctly formulated for a particular application, an optimally arranged mixed collector suite delivers the following improvements to the flotation process: • An increase in the flotation kinetics • Improvement in coarse, or middling, particle recovery • Reduction in total dosage requirement • Best results are found from testing the ratios of the collectors. This is of critical importance. In all an optimally formulated mixed collector system usually delivers an increase in paymetals recovery of 1–4% absolute, with a gain in concentrate grade in the range 10–20% relative. In recent years, the addition of semi-conductor theory and associated electrochemistry has contributed significantly to this toolbox by way of identifying optimum domains of Eh and pH for the flotation of individual minerals. In the case of mixtures of minerals, this is where the mixed collector system delivers significant value by way of presenting a mixed set of collector radicals and dimers in a common Eh and pH domain for overall performance. This calls on a fundamental understanding of organic chemistry, mineralogy, semiconductor theory, and electrochemistry. Whereas the selection of grinding media type effectively influences the Eh, the pH can be easily controlled by pH modifiers. The theory of this system, and some industrial case studies, are discussed.

By J. W. Evans

Mathematical modeling has now become a standard technique in the development of new technology and the improvement of existing technology in the processing industries. Physical modeling has a longer history but a smaller following at present. The paper reviews some examples of the application of both types of modeling in non-ferrous metal extraction, particularly within the copper and aluminum industries. The objective is to show that well founded models can lead to results that have practical consequence in scaleup, design and operation.

Jan 1, 1993

By I-Min Lu

An electric field was applied to a metal-bearing kaolinite specimen to investigate the efficiency of electro-osmosis in removing heavy metals from contaminated soils. The electric field induces a flow of water through the porous medium, called electro-osmosis, which is superimposed on the hydraulic flow. Because the electro-osmotic flow is relatively stronger in smaller pores, it can enhance the displacement of contaminated solution by fluid convection. Furthermore local changes in pH caused by the electrode reactions can affect adsorption equilibria and the distribution of solutes between the solution and the solid surfaces. The electro-osmosis experiments were conducted by applying either a constant current or a constant voltage across 8-cm inside diameter, 25 to 30-cm long specimens of kaolinite clay with graphite electrodes. Samples of the pore fluid and of the clay were analyzed to determine metal content, pH, and conductivity as functions of time and position. Results show that removal of heavy metals from soil can be accomplished effectively by electrokinetic treatment of sufficient duration. Approximately 95% of the lead was removed after 189 days.

Jan 1, 1996

By Thomas W. Chapman, Shi-Chern Yen, I-Min Lu

"An electric field was applied to a metal-bearing kaolinite specimen to investigate the efficiency of electro-osmosis in removing heavy metals from contaminated soils. The electric field induces a flow of water through the porous medium, called electro-osmosis, which is superimposed on the hydraulic flow. Because the electro-osmotic flow is relatively stronger in smaller pores, it can enhance the displacement of contaminated solution by fluid convection. Furthermore, local changes in pH caused by the electrode reactions can affect adsorption equilibria and the distribution of solutes between the solution and the solid surfaces.The electro-osmosis experiments were conducted by applying either a constant current or a constant voltage across 8-cm inside diameter, 25 to 30-cm long specimens of kaolinite clay with graphite electrodes. Samples of the pore fluid and of the clay were analyzed to determine metal content, pH, and conductivity as functions of time and position. Results show that removal of heavy metals from soil can be accomplished effectively by electrokinetic treatment of sufficient duration. Approximately 95% of the lead was removed after 189 days.IntroductionRemediation of soils contaminated with toxic chemicals is a difficult and expensive task. Washing or leaching are not particularly effective if the contaminate is sequestered in small pores; hydraulic flows of water pass through larger pores leaving the smaller pores relatively untouched. Electro-osmosis appears to be the most promising new technology for removing heavy metals and organic substances from contaminated soils (Segal, 1980; Hamed et al., 1991, Masliyah, 1994).Electro-osmosis is one of several electrokinetic phenomena that occur through the interactions among an electric field, fluid motion, solute adsorption, and the existence of a net charge on a solid-fluid interface (Newman, 1991, Masliyah, 1994). Electro-osmosis refers to the fluid flow in a porous medium that results when an electric field acts on the mobile region of the electrical double layer, the solution-side region of charge separation that exists at the pore walls."

Jan 1, 1996