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By John L. H. Patterson

Handheld XRF has become the favorite way of measuring the content and identity of alloys in the field. This is because of the very portable nature of the instrumentation and its simple operation. However, these analyzers have been unable to determine the concentration of the light elements like Mg and Si due to the very low energy of the x-rays produced by these elements. In the past accessories such as vacuum and He flush have given some analyzers the ability to determine these light elements with modest detection limits. The introduction of the Silicon Drift Detector (SDD) into this class of instrumentation has added a new level of analysis capability to portable XRF instrumentation. X-ray fluorescence is achieved by exciting a sample with a beam of x-rays, which in recent portable equipment are generated by a small tube. This results in the emission of characteristic x-rays from the sample under test. By measuring the energy of each x-ray it is possible to determine what element generated it. By counting the number of x-rays at each energy it is possible to determine the concentration of each element. The detection limit for each element is dependent upon the number of x-rays which reach the detector. As the number of x-rays increases the detection limit will improve. One of the major factors in an x-ray reaching the detector is the energy of the x-ray. As the energy of an x-ray increases the probability of that x-ray reaching the detector increases. The energy of an x-ray is inversely proportional to the atomic number (AN) of the element generating the x-ray. For example, an iron x-ray (AN=26) is 6.40 keV while an aluminum x-ray (AN=13) is 1.49 keV. As the energy decreases, the detection of the x-ray becomes less and less probable because the x-ray may be absorbed by the windows which are part of the instrument and detector or the air in the path between the sample and detector. In SiPIN based portable XRF analyzers, the lowest element which is detected with acceptable detection limits is normally considered to be Ti (AN=22). The detection limits for 60 second measurements on typical SiPIN XRF analyzer are given in Table I. Thus, portable analyzers have not been useful for measurement of aluminum and titanium alloys as major components of these alloys are Mg (AN=12), Al (AN=13) and Si (AN=14).

Jan 1, 2009

By J. C. Huyhua

The effect or various oxidants on gold and silver dissolution in thiourea solutions (0.05 M in H2SO4) was studied using the rotating disc technique, a.t 2s c and 600 rpm. These studies were carried out at constant (4:1) initial molar ratio or thiourea to oxidant concentrations, to produce 50 % thiourea. oxidation. The initial dissolution rate of gold was approximately four times higher in the presence. of ferric sulfate (5.37 x 10-3mg cm-2 s-1) than in the presence of hydrogen peroxide (H2O2), potassium persultate (K2S2O3), or monopersulfa.te (KHS06). The dissolution rates for silver were considerably lower than gold for the same oxidants. Oxidation of thiourea in the presence of peroxygen and persulta.te compounds is a. fast reaction and it is completed in less than ten minutes. On the other hand, the oxidation or thiourea with? ferric.sulfate is slow, yielding a second-order reaction rate constant k = 6.09 I mol-1 h-1. Sulfur formation in the ferric thiourea system begins when ferric ion reduction approaches to completion. With hydrogen peroxide, sulfur is observed at lower thiourea concentration than ferric. Suifate. The presence of a large excess or free thiourea i.e., s to 20 % thiourea oxidation) retards sulfur formation and maintains favorable dissolution rates. Finally, carbon-in-leach experiments indicate that thiourea solutions a.re stable for several days, with ferric sulfate or hydrogen peroxide. The dissolution rates of gold and silver doubles in the presence or activated carbon when hydrogen peroxide is used as oxidant.

Jan 1, 1989

By E. Oshima

In May 1991, a New Mitsubishi Continuous Copper Smelter Line started operation at Naoshima. Recently, it has been continuing steady operation and one and a half year campaign life has been achieved. In 1996, new records of on line time, the amount of copper concentrate treated and copper anode production were achieved. 1t proves the superiority of the process with respect to pollution control, energy efficiency, flexibility and easiness of the operation and over all economy including off gas handling cost. Furthermore, .plans are underway to prolong the campaign life for two years and to improve the process efficiency. This paper describes recent operation, improvements, and a future capability study.

Jan 1, 1998

By Etsuro Shibata

The saturated solubility of chromium oxide and the valence of chromium in the slag are important matters when considering how to effectively utilize chromium-containing slags. The experimental data of various types of slags cited in the literature were arranged according to the optical basicity in order to evaluate the effects of the oxygen potential and the slag composition. The saturated solubility of chromium oxide and the Cr2+/ Cr3+ ratio tend to decrease with the increase of the optical basicity of the slag at an oxygen potential below 10.5 atm. However, at an oxygen potential of 0.21 atm, the saturated solubility and the Cr6+/Cr3+ ratio tend to increase with an increase of the optical basicity. A practical approach was suggested to reduce chromium in the stainless steel slag and simultaneously recover it as a ferroalloy by the direct smelting reduction of chromium oxide in the molten slag using some reductant in a small furnace.

Jan 1, 2003

By H. Y. Sohn

The considerable progress made in the sulfide smelting technology since the first International Sulfide Symposium of 1983 is discussed. The new developments and innovations have largely been driven by the recognition of environmental concern as well as the need for increased productivity. The smelting technologies for various nonferrous metals are reviewed, with an emphasis on the industry trend towards larger plants and continuous processes. The tremendous advances made in process modeling and computer simulation to describe the complex smelting processes are also reviewed. The goal of these mathematical models is the quantitative description of the processes and the reactors that will provide a means for the control and optimization of smelting operations as well as the optimal design of the operating conditions and the reactors. Environmental issues remain a key consideration in the smelting industry. One of the most remarkable improvements made in the last fifteen years since the 1983 Sulfide Smelting Symposium is the rapid increase in the sulfur capture by nonferrous smelters. This and other related issues are briefly discussed. Finally, the challenges that the smelting industry faces as the new millenium approaches are discussed. The industry continues to face technical challenges to improve productivity and efficiency, while being responsive to ever-increasing public pressure for environmental protection. It also faces external challenges from factors that may cause the reduction of metal uses as a result of substitutions by other materials. Another serious challenge and dire consequence that the primary metals industry is expected to face is the serious diminution of university-educated manpower as well as basic-research output. To remain competitive and healthy, the industry should take up the void left by the complete disappearance, at least in the U.S., and the reduction in other nations, of the governmental support of higher education and basic research in the field of primary metals production.

Jan 1, 1998

By Kymberley Worrell

The Cripple Creek and Victor Gold Mine was acquired by Newmont in August 2015. The high grade flotation mill project was commissioned in February 2014. The mill to date has been throughput limited due to mechanical and design issues. In order to create the most value from a throughput limited plant a campaign to provide timely ore characterization was undertaken. A diagnostic leach methodology was developed to determine gold associations by ore type. The resulting associations were then used to characterize feed blend; gold losses and optimize gold production. The diagnostic methodology is presented along with discussion on flotation implications.

By Ilija Ilic

Recovery of tin from tinplate and production of good-quality detinned-plate for further processing in ironworks has been the subject of interest for many years. Tinplates are mostly used for production of tin containers for food industry and consumer goods. The research carried out so far included determination of the parameters of dissolution of tin from tinplates by alkaline solution of NaOH and electrochemical recovery of tin from the alkaline solutions. During leaching, NaNO3 and methanitrobenzoic acid (MNBA) as oxidants were studied. By leaching the waste tinplate which contains 0.31 % of tin with a solution of 1.12 mol/dm3 NaOH, 0.26 mol/dm3 Na2CO3 and 0.09 mol/dm3 MNBA at temperature of 70°C for 60 mm, a degree of tin leaching of 97 % was attained. MNBA facilitates oxidation of Sn2+ into Sn4+ suitable for obtaining compact, and not spongy, Sn cathode deposit, as it was the ease earlier. Recovery of tin by electrolysis from solutions obtained by leaching was studied to determine the effect of electrolyte composition on the quality of cathode deposit and the degree of electric current efficiency. Experimental results obtained at a laboratory level were checked on an enlarged laboratory set up where continuos leaching of tin from waste tinplate and its electrolytic recovery from the solution obtained were carried out. The experimental set-up -operated under semi-industrial conditions, and about 500 kg of waste tinplate was processed yielding about 1.160 kg of tin (99 % Sn).

Jan 1, 2000

By Wang Zhi

High-Mg-content concentrates are usually treated in Jinchuan flash smelting Furnace. Because the viscosities of high-Mg-content slag is very high, the operation of flash smelting becomes very difficult. To solve this problem, the viscosities of the semi-synthesized FeO-MgO-SiO2 slag of different compositions were measured. The results showed that when in the slag the weight percentage of MgO [w(MgO)] is 6-10%, the ratio of the weight percentage of iron to that of Si02, w(Fe)/w(Si02) is 1.1-1.4 and the temperatures are within 1473-1773K, the slag viscosities increased with the increase of W(MgO) and w(Fe)/w(SiO,). When w(Mgo)<6%, the smelting temperature should be controlled at I 300°C in order to to keep the smooth operation. When w(MgO)>10%, the temperature should be kept above I 633K. When the content of MgO is higher, a lower viscosity slag can be produced by decreasing the ratio of w(Fe)/w(SiO,). The appropriate ratio of w(Fe)/w(SiO,) for Jinchuan flash smelting furnace is about 1.2.

Jan 1, 2003

By P. F. Kerr

This is not a conventional professional paper. It deals mostly with personal experiences. These concern a background in applied mineralogy. Your committee asked me to do this. I accepted with a California enthusiasm which has since diminished with the approach of a Chicago winter. Nevertheless, I wish to thank your committee and also to apologize in advance for omissions and inadequate statements, as such a paper must possess. My introduction to applied mineralogy took place in 1922 at Stanford University. Physicists had recently demonstrated that crystalline powders would reflect x-rays in a systematic manner. Professor A.F. Rogers sug¬gested that significant x-ray reflections might be obtained from powdered opaque minerals. With the aid of Professor D.L. Webster in the Physics Department, I constructed an x-ray diffraction outfit. It was a crude affair, but it worked. Starting with 1924, we secured recognizable patterns of a goodly number of ore minerals (1,2,3). Today x-ray diffraction outfits are common, and a card system of mineral identification is constantly used.

Jan 1, 1981

By Linlin Wu, Marlen Bertram, Chris Bayliss, Bernard de Gelas, Samantha Jones, Kurt Buxmann

"Environmental management is one of the industry cornerstones of sustainable development. In order to understand fully the environmental aspects associated with the raw material acquisition, production, use, and end-of-life operations of aluminium products, the Aluminium Industry has developed an approach based on Life Cycle Analysis (LCA) methodology.Within this framework, the Primary Aluminium Industry has established a global Life Cycle Inventory (LCI) data set. Inventory flows include inputs of raw materials, energy and water, emissions to air and water, and solid waste.This paper presents the latest LCI data update by the International Aluminium Institute for the year 2010, based on a survey of aluminium plants globally, including bauxite mining, alumina refining, anode production, electrolysis and casting. This update also includes some performance tracking based on the last LCI data collection in 2005, reflecting progress in efficiency and technology, as well as changes in the geographical location of the industry [2010 data pending]. IntroductionIn 2010 the Primary Aluminium Industry produced a total of 41 Mt of aluminium. The International Aluminium Institute (IAI) membership represents approximately 70% of total global production. The industry recognises the importance of co=itting to reducing the environmental impacts of producing primary aluminium, and the significance of working towards a more sustainable future. As part of this co=itment the IAI has developed an in depth Life Cycle Inventory programme, in which data is collected every five years, with supplementary key metrics collected annually.In 2003 the IAI released its first Report ""Life Cycle Assessment of Aluminium: Inventory Data for the Worldwide Primary Aluminium Industry"" based on the year 2000 with an update Report released in 2007, based on 2005 data.This paper presents the latest update for the year 2010 [2010 data pending]. It has been prepared with the same view of collecting all significant Life Cycle Inventory data (raw materials and energy use, air and water emissions and solid waste generated) associated with producing primary aluminium ingot from bauxite ore, with worldwide coverage. The intended purpose of the Inventory Report is to accurately characterize resource consumption and significant environmental aspects associated with the worldwide production of primary aluminium. It reflects the fuct that primary aluminium is a globally traded co=odity."

Jan 1, 2012

By R. Elliott, H. Bayati

"Effect of time and temperature on microstructure and mechanical properties of an austempered ductile iron, ADI, of composition 3.6%C, 2.6%Si, 0.4%Cu, 0.2%Mn are reported. Xray analysis and. microstructural observations indicate that lowering the working temperature, aging temperature, increases the lifetime of ADI significantly. Results show· that lowering the aging temperature increases the strength and reduces the ductility of ADI. DSC traces for ADI austempered at 340°C are presented. Comparison of the DSC analysis and kinetic measurements demonstrates that the DSC traces can be· used to predict the life time of ADI successfully.IntroductionAustempered ductile iron, ADI, is one of the most significant developments in cast iron technology over the past two decades. Outstanding properties of high yield, ultimate strength, ductility, fatigue and wear· resistance make ADI suitable for a range of applications including gears, connecting rods, crankshafts and agriculture machine components. The austempering reaction in cast iron occurs in two stages, Fig. I, in contrast to the single stage reaction in steel. In stage I the relatively low carbon austenite produced during austenitising transforms into ferritic plates and high carbon austenite, a metastable structure called·ausferrite. The high carbon ailstenite and supersaturated ferrite produced in stage I decompose into ferrite and carbide in stage II: to form a structure similar to the bainitic structure in steel. This behaviour exposes a well-defined processing window, t1 - t2, over which the maximum amount of ausferrite is produced, Figure 1. Whereas the bainitic structure determines the properties of austempered steel, ADI properties are mainly affected by volume fraction of retained austenite (VRA), austenite carbon content (ACC), unreacted or martensite volume fraction (UA V), compositiori and amount of carbides, and morphology of ferritic plates[l,2]. Due to the detrimental .effect of martensite and carbides on properties of ADI, an ideal structure of ADI consists only of ausferrite [l,2]. Thus, it is common to determine the processing window for each austempering treatment in order to identify the optimized austempering time. Decomposition of austenite (stage II) signals the end of the life time for an ADI component, therefore, the aging behaviour of ADI at different working conditions can be studied by determining the t2."

Jan 1, 2000

By M. D. Strachan

Technical & Procurement Services Limited (TECHPRO) in Ashford, Kent, UK, have been appointed as Project Managers for the major rehabilitation of the Copper Smelting complex of Nkana Division, Zambia Consolidated Copper Mines Limited, (ZCCM) Zambia. In outline, the overall scope covers three main areas: a) Transfer and implementation of new technology into Zambia for the production of primary copper. b) Replacement of gas collection and gas treatment circuits to guarantee high quality feed to the acid plants. c) Completion of a number of minor projects in the copper smelter and associated utility plants to complement changes in the primary smelting technique. This paper describes the Project Management methodology and style used by TECHPRO to tackle typical problems that arise in retrofit projects of this type. Reference is made specific aspects of the smelter projects to illustrate solutions to the problems. The subjects. addressed highlight the complexities not only of having a -Client 5,000 miles from the Project Office, but also the difficulty of co-ordinating and controlling the performance of min sub-contractors who are also geographically distant.

Jan 1, 1991

By Bryce Clark

Cobalts history from the 14th Century is outlined, with a look at its various sources over that period. The present sources and quantities are given, when in 1994 it is an equal co-product of copper in Africa and nickel elsewhere (Canada, Australia, Russia). Future trends in this scene are also examined. The final section deals with cobalts uses in superalloys, magnets, colours, electronics, chemicals, and examines trends in its markets. Supply and demand in co-product cobalt are shown, based on the latest production figures.

Jan 1, 1995

By F. Kongoli

Viscosity is an important parameter of copper smelting and converting processes. It affects the settling of matte or metal droplets in the slag, distribution of elements etc, Despite this importance, confusion exists on the viscosity of copper smelting slags as a result of disagreements found among the measured viscosity data of several authors especially in the slags of high ferric iron content and close to magnetite precipitation. In this work a critical review of the existing data on the viscosity of copper smelting slags has been first carried out and the effect of oxygen potential on the viscosity of copper smelting slags has been clarified through a coupled quantification of viscosity and liquidus temperature. The confusion in the literature has been clarified and the importance of the relation between the viscosity and the liquidus temperature is discussed,

Jan 1, 2003

By D. Gu, R. G. Anthony, C. V. Philip, M. E. Huckman

"In this paper, we review the equations needed to construct an ion exchange column model. These models contain three major components: 1) a differential material balance around the column, 2) a differential material balance around an ion exchange particle, and 3) a constitutive equation for diffusive flux. We then examine the ability of a fairly simple mathematical model to predict ion exchange column experimental data. This model contains the traditional absorption theory equations and is used to predict the behavior of a column filled with a hydrous crystalline silico-titanate and which is removing trace amounts of Cs+ from a high pH, complex electrolyte solution. Finally, we propose replacing Fick's law with the Nemst-Planck equation as the constitutive equation for diffusive flux. We use a NemstPlanck type model to predict batch experimental data, then evaluate it by comparing it's ability to predict experimental data to that of a more traditional Fick's law type model. The data from this comparison suggests that the Nemst-Planck type model yields better results.IntroductionMillions of gallons of strongly basic, radioactive waste are currently stored in underground storage tanks at Hanford and Savannah River and several locations within the United States. Due to the limited life expectancy of the tanks, there is a pressing need to remediate these wastes. This need has prompted the recent development of new ion-exchange materials for removing radioactive elements from aqueous solutions. A novel material called TAM-5 has been developed jointly by Texas A&M University and Sandia National Laboratories. TAM- 5, a crystalline silico-titanate, is highly selective for Cs + in the complex electrolytic solutions typical of these wastes. It is stable in very basic solutions and in radioactive environments [1, 2 ,3]. In laboratory testing to determine the selectivity of various materials, TAM-5 was superior to other candidate ion exchangers [4, 5]. The selectivities were determined by measuring a distribution coefficient, Kd, which is defined as the concentration, gig or mmols/g of Cs in the solid phase divided by the concentration, mg/L or mmols/mL, of Cs in the liquid phase. The units of Kd are ml/g or L/kg. Table 1 shows Kd values for TAM-5 compared to 9 other candidate materials in a typical waste solution [6]."

Jan 1, 1996

By Avijit Moitra

The behavior of the solidifying shell in the early stages of solidification has an important influence on the final quality of continuously-cast steel slabs. In order to understand the thermal and mechanical behavior of the shell, a two-dimensional transient piecewise-coupled finite-element model has been developed. The model simulates a transverse section of the slab as it moves down through the mold and incorporates the effects of heat conduction, solidification, shrinkage, turbulent fluid flow, thermal distortion of the mold and the visco-plastic behavior of the steel. Coupling between the thermal and the mechanical model is based on the mutual dependence of heat transfer across the interface between the shell and the mold and the size of the gap. The effects of mold distortion and taper on the gap size are also included. The effect of fluid flow has been incorporated via a heat flux imposed at the solid-liquid interface, which is obtained from a separate fluid flow model. The high temperature creep and plasticity of the steel is incorporated through a unified constitutive law defining the inelastic strain rates as a function of temperature, time and stress state. The model can be applied to various problems in continuous casting, such as the formation of surface defects and the design of mold taper.

Jan 1, 1992

By Xiangwen Wang

Electrochemical measurements associated with the electrowinning of lead metal from concentrated brine (NaCI) - lead chloride (PbCI,) electrolytes at temperatures in the range 328 to 353°K (55 - 80°C) were conducted. The electrodeposition of lead metal onto a lead rotating-disk electrode may be described by the electrodic reaction: {PbCl 4 2 + 2e- = Pb° + 4Cl-} The deposition-overpotential requirements are low (approximately 41mV per decade of current density - Am+), with a corresponding high exchange current (approximately 0.018 A.cm2). The diffusion coefficient of the electroactive PbC142- species in a 3.5 NaCl electrolyte at 353°K was insensitive to the total PbCI, concentration (0.01 to 0.1M), and its value was found to be (1.21*0.1)~10-5 cm2Is with a temperature-sensitivity coefficient (E,/R) of approximately 1.98x103K-1 (328OK(T<353OK).

Jan 1, 1993

By D. H. Magoon

The zinc smelter of Cominco Ltd. at Trail, B.C. Is the largest In the western world. A total of 550.000 tonnes of concentrate are proceed at the smelter annually. Approximately 80% of the zinc concentrate is roasted and the remainder Is treated by aqueous oxidation preaaure leaching. The zinc concentrate roasting and sulphur dioxide gas processing plants have undergone many changes over the years. This paper describes the processes and equipment currently used for concentrate roasting, S02 gas cooling and cleaning, mercury removal, sulphuric acid production liquid S02 production, and tall gas S02 scrubbing. The recent Installation of an advanced process control system for the operation of these Integrated processes Is also described.

Jan 1, 1990

By Patrik Fredriksson

Thermodynamic data concerning FeO-containing slags is of importance in ladle refining of steel. With a view to generate a set of reliable and self-consistent thermodynamic data for these slags, experimental determination of the activities of FeO in binary and ternary slags was carried out using the gas equilibration method involving CO-C02-Ar gas mixtures at steelmaking temperatures. The slag samples in Pt crucibles were quenched after the equilibration and subjected to chemical analysis. The thermodynamic activities of "FeO" in the slags were calculated from the experimental data. The results are incorporated into a thermodynamic description of silicate melts in the present laboratory. The model is based on a Temkin-Lumsden approach and is able to compute the thermodynamics of higher order systems from the lower order ones.

Jan 1, 2003

By Tuula Mäkinen

One of the latest applications of the Outokumpu Flash Smelting Technology is the direct smelting ,of nickel concentrates to metallised low-iron nickel mattes. Compared to the conventional nickel smelting, the new DON process needs a lower number of smelting vessels resulting in considerable economic and environmental benefits. Fundamentals of smelting nickel concentrates in one stage to low-iron mattes are presented. Properties of nickel. smelting slags with an emphasis of the slag fluidity at high MgO-levels are also discussed. Conditions prevailing in DON mattes at high oxidation degrees are presented as well as their influence on the behaviour of such mattes in the settler and on tapping the furnace. Distributions of elements in the direct smelting are presented and compared with the conventional process. A further comparison is made with pilot-plant data and the industrial scale.

Jan 1, 1998