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By David J. Roha

"The harsh environment of the Carbothermic Aluminum process makes necessary numerical modeling as a means of process visualization and understanding. A brief survey of the various numerical models, with emphasis on CFD, applied in the development of the process is presented.IntroductionThe environment of the Alcoa Carbothermic reactor is necessarily a harsh one, with temperatures approaching 2100 °C and plenty of reactive dust and vapors. As such, it is difficult to directly observe what is actually taking place. Thermocouples can last for a few minutes but are eventually destroyed. The openings to optical pyrometers become occluded with dust and condensation. Graphite sheathing embrittles, reacts away or becomes clogged with condensate. Dip-samples on steel rods are routinely taken, but their interpretation is often unclear.Those measurements that can be reliably taken are invaluable, but often do not provide a complete picture. Therefore from the very inception of the project both physical and computer based models have played an important role. Modeling provides an intuitive understanding of the processes that might be taking place and in very many cases approach quantitative prediction. I will briefly touch upon computer-based modeling performed at Alcoa over 12 years of the Carbothermic project, with special emphasis on CFD. The explanation of physical models is perhaps best left for those with the greatest familiarity with them"

Jan 1, 2012

By Lisa E. Helberg

"Titanium tetrachloride is produced through the chlorination of a variety of titanium bearing ores, some occurring in nature, and others enriched in titanium content by a variety of ""beneficiation"" processes. The chlorination step can produce a variety of metal chloride impurities, such as iron chlorides and vanadium chlorides, which must be removed from the TiC14 before it can be used to produce pigmentary TiO2, titanium metal or for any other commercial use. The requisite manipulations involve both physical and chemical separations in a multi-step process. The history of various purification strategies will be discussed.TextThere are a wide range of titanium-based products available, all of which start with titanoferrous ore of some type. Two main routes are used to convert ores into products, known as the sulfate and chloride processes. The sulfate process uses sulfuric acid to digest the ore, separate the impurities, and then precipitate titanium dioxide from the resulting titanyl sulfate (TiOSO4) via metatitanic acid. This process can also supply TiOS04 for other applications."

Jan 1, 2011

By I. Hilario, D.Y. Medina, V.J. Cortés, J.D. Muñoz

The process of Tribofinishing is investigated as a memns to reacha state of quality for the surface teated. During the said process there occurs mass transferat the interface of the piece to be treated and the abrasive charge (abrasive plus additives). This stiuation is studied for Titanium as a possibility for application in prosthesis. With these results is intended to produce a model of the mass transfer that would allow having further control of the process.

Jan 1, 2012

By Francis C. Furman

Microscopic evidence indicates that the high sinterability of certain commercial dolomites is tied to specific dolomite textural characteristics. This study encompasses detailed characterization of the unprocessed dolomite and sintering doloma results. The chemical and mineralogical compositions, insoluble residue, chemistry homogeneity, crystal size, primary carbonate texture, secondary dolomite texture, deformation structure, porosity type, porosity, and density of the raw dolomite were observed. These characteristics are compared with sintering trials of <74um powder-compacts samples in which holding times were varied. The evolution of the dolomite characteristics are reviewed and related to the final sintered doloma characteristics. The critical characteristics of a single-stage sintering brick dolomite are the following: 1) primary oolitic texture, 2) dolomite purity, 3) dolomite stoichiometry 4) minimal impurities, less than 1 weight {%} Fe2O3 Al2O3 and SiO2, 5) chemical homogeneity, 6) high density, 7) very low porosity, S) very coarse homogeneous crystallinity, 9) nonplanar dolomite texture, 10) abundant strain related slip microdeformation structures, 11) minimal subsequent alteration. Even with grinding to <74um the nonplanar dolomite texture and slip deformation still have a major effect on doloma sintered density. The three newly identified characteristics of single-stage sintered refractory brick dolomite are their primary oolitic texture, secondary nonplanar texture and abundance of stress related microdeformation structures. The primary oolitic texture reflects a homogeneous pure carbonate with respect to chemistry and crystal size secondary nonplanar texture produces crystals with large surface area to volume ratio. Stress related slip deformation moves CO, groups in to the same site of another CO, group but different orientation which is very unstable. All of these characteristics may facilitate the formation of higher density dolorna sinters.

Jan 1, 1995

By H. M. . van der Donk

In this work an overview is given about the techniques available for the removal of metallic impurities from molten aluminium. The overview is focused on the removal of iron. Also, some experimental results are given about the creation of iron-rich intermetallic compounds in an aluminium system, which are subsequently removed by gravity segregation and filtration techniques. This work is part of an ongoing research project of three major European aluminium companies who are co-operating on the subject of recycling of aluminium packaging materials recovered from household waste by means of Eddy-Current techniques. Using this technique the pick-up of some contaminating metals, particularly iron, is almost unavoidable.

Jan 1, 1995

By Harvey Alter

National attention in, recycling focuses on municipal solid waste (MSW), even though only about 50&apos;million tons or so of MSW can be recycled, including grass, leaves and other yard wastes. The scope and value of the recycling of industrial "wastes" is much greater. It is possible to account for some 240 million tons of material recycled at the industrial scale annually, which is likely a conservative estimate. Some of this recycling reduces what would otherwise be hazardous waste to &apos;comrnodities and non-hazardous residue. Global trade in recycled commodities is outlined, as well as the-effect of the Basel Convention on the Trans boundary Movement of Hazardous Wastes A recent Decision under the Convention can, diminish the trade; deny developing countries needed secondary raw materials, and put world markets in chaos. Current U.S. government policies and activities toward ratification of the Convention, and possible new regulation of industrial recycling activities, will be discussed. There are federal proposals that would regulate industrial recycling differently for on-site and off-site facilities and judge legitimate or "sham" recycling according to the concentration of so-called "toxics along for the ride."

Jan 1, 1995

By Xiaowen Liu

The thermal decomposition of diaspore was investigated by thermogravimetry (TG),differential scanning calorimetry (DSC), X-ray power diffraction(XRD),infrared (IR)spectrain this paper. The thermal decomposition mechanism of diaspore was discussed according to Coat-Redfer equation. It was found that the decomposition of diaspore was carried out at 500?,and the peak temperature was 530?. The electrovalent balance of diaspore was destroyed. The previous crystal structure was changed. a- Al2O3 was obtained after thermal decomposition. The activation energy is 287KJ/mol.

Jan 1, 2006

By Chikabumi Yamauchi, Mitsuru Tanahashi, Toshiharu Fujisawa

"Thermodynamic properties of impurities in molten silicon are of prime importance in developing economical production methods of solar grade silicon. In the present research work, thermodynamic properties of boron, the most difficult element to remove from molten silicon, were measured by chemical equilibration techniques at 1723 and 1773 K. Activity coefficients and self-interaction parameters of boron in molten silicon were determined by equilibrating the melt with solid BN under controlled nitrogen partial pressures. Interaction parameters between boron and nitrogen in molten silicon were also determined by equilibrating the molten Si-B alloys with solid Si3N4• Based on the data obtained, the stability diagram of the Si-B-N system was established.IntroductionPhotovoltaic power generation using a silicon solar cell is expected to be the most promising energy source, because it is inexhaustible, cleaner and more safety than conventional energy sources, such as thermal or atomic power generation. At present, expensive off-grade silicon for semiconductor (SEG-Si) is used for a solar cell production. However, if a large-scale photovoltaic energy conversion using silicon solar cell comes into wide use in the near future, silicon will be sure to be in short supply for the cell. Therefore, a development of a new large scale process for solar grade silicon (SOG-Si) production is definitely necessary, which can remove contained impurities from silicon.Among the impurities contained in silicon, boron is one of the most difficult ones to remove by a zone melting or an unidirectional solidification, because its segregation coefficient in silicon is close to unity (0.8). In addition, boron behaves as a p-type silicon semiconductor dopant and, therefore, its content in SOG-Si must be severely controlled. Although some attempts to remove boron by various metallurgical methods have been carried out [I -4], quantitative analysis has not been made due to lack in the information on the thermodynamic properties of boron in molten silicon. From this view point, the activity of boron in molten silicon was determined in the present study by chemical equilibration techniques at 1723 and 1773 K."

Jan 1, 1998

By B. P. Sereda

The properties, characteristics and phase structure of chamotte refractories produced with the usage of mullitecorund chamotte and caoline have been given. The comparison of new refractory C-45 obtained by us and refractory C-43 produced by traditional method has done. The physical-chemical properties of refractories is reviewed. The visual porosity, density and pore characteristics of given refractories was calculated. It is established that C-45 has the less gas permeability then C-45 that gives melting units more stability. The petrographical microstructures of refractories have been done. The main phase structures and their influence on refractories properties have been observed. It is established that refractories with mullitecorund chamotte adition has more advantages then refractories gained by traditional method and can be applied to melting units.

Jan 1, 2010

By Matthew Jeffrey

Leaching, cementation, electroplating and flotation are all electrochemical phenomenon. They are also key processes in the hydrometallurgical treatment of metals. Unfortunately electrochemical methods tend to be under-utilized when studying these processes and one possible reason for this is the confusion surrounding the large number of electrochemical techniques available. In this paper four former PhD students of Professor Ian Ritchie present an insight into how one electrochemical technique can be used to compliment rate/kinetic studies. The paper details how to perform the experiments, interpret data, and recognize complications with the results. Examples where this approach has been highly successful are presented, and include: cementation of zinc by aluminium, cementation of copper by nickel, cyanide leaching of gold and the cementation of gold thiourea by mild steel. The examples illustrate that this universal approach adopted by Ian Ritchie provides the key to understanding the mechanism of many hydrometallurgical reactions.

Jan 1, 2003

By Shengli Wu, Wei Huang, Xinliang Liu, Kaifa Zhang

The slagging behavior, the phase of primary blast furnace slag and its transformation law of structure for the single furnace burden were studied in this paper. The results showed that the formation of primary slag was controlled by CaO/SiO2, Al2O3 content, MgO content, reducibility, iron content and porosity of the furnace burden. Fayalite (2FeO•SiO2) was easily formed from acid ferrous furnace burden while kirschsteinite (2(Fe,Ca)O•SiO2) was produced from alkaline ferrous furnace burden

Jan 1, 2015

By A. Treverrow, G. A. Brooks, H. K. Worner

"The work by H.K Worner and co-workers at CRA in the 1960s, and early 1970s, established that molten metals could be refined continuously utilising counter current flow of metal and slag. Womer also demonstrated that counter current refining could produce highly refined metal products. These developments coincided with the advent of high intensity metallurgical reactors in both the ferrous and non-ferrous industries (e.g. BOS, Q-BOP and later Sirosmelt) that utilised high levels of gas injection to produce rapid stirring and very fast reaction. These new generation of high intensity metallurgical reactors allowed high tonnage rates through relatively small volume vessels.Whilst, it is well known that the counter current flow of reacting phases offers the potential of efficient mass transfer and high purity products, the application of counter current reactors to molten metal/slag systems has been criticized on the basis that they suffer from either low intensity or, alternately, from poor refining due to excessive dispersion. These criticisms relate to the balance between intensity and the refining capacity of a reactor. That is, whilst high levels of mixing transversely to the direction of flow promotes high mass transfer, longitudinal mixing (dispersion) is detrimental to refining. Of course, mixing in one direction invariably leads to mixing in other directions, thus creating a playoff between high mass transfer and excessive dispersion.This balance between intensity and refining has been the subject of recent studies overseas, and at"" the University of Wollongong, using cold modelling techniques to evaluate the effect of mixing on dispersion in a counter current refining launder. These studies have shown that for a given geometry and mixing regime, dispersion decreases with increasing flow of liquid phases. This means that whilst high mass transfer cannot be achieved in a refining launder without sacrificing the degree of refinement, there is no impediment to achieving high productivity through such a system, in fact, high through puts may favour good refining. Thus, it may be possible to match a high productivity smelting operation with a equally productive counter current refining stage."

Jan 1, 1996

By R. D. Prengaman

Lead usage in paint, anti-knock gasoline additives, pipes, seals, and solder has declined markedly over the past 30 years. Products utilizing the unique properties of lead and its ability to be recycled have survived and grown. These products include shielding, glass (particularly TV and computer screens), sheet for roofing, stabilizers for PVC, insoluble anodes for metal production, electronic solders and lead acid batteries. With the loss of markets many companies have decreased lead product development efforts. Much of the patent lead materials development is devoted to lead acid batteries. In the past 25 years, the automobile battery has been almost doubled in power and reduced in weight, leading to a nearly three-fold increase in performance. Corrosion-resistant lead alloys and improved battery designs have made battery lead usage more efficient. The same corrosion-resistant battery alloys are utilized to increase the life of electrowinning anodes. The challenge for lead product development is not only to maintain and improve the existing lead products, but also to develop the growing lead acid battery market for telecommunications, uninterruptive power sources, remote area power, hybrid and electric vehicles. Lead

Jan 1, 2000

By Heikki Tuovinen

The total utilization of raw materials and energy is the most important criterion when planning. industrial processes. The main goal is clearly to use the raw materials and energy as effectively as possible in order to make the desired products directly in the primary process itself&apos;, or to recycle unused materials and energy either as such, or after cleaning back into the process. However, few industrial processes are so straightforward. Most processes generate by-streams of materials and energy, which cannot be recycled directly and it is namely these by-streams which tend to remain as wastes. These by-streams are slags, dusts, vaporized metals, liquids, slurries, sludges, gases etc. Most base metal processes produce all these by-products. Waste water and gas emission controls and regulations are tightening all the time, so new processes must be developed to keep pace with these requirements. These processes generate more solid wastes, which must be utilized or at least processed into a harmless form landfilling. Municipal and hazardous wastes also contain valuable materials and energy, which must be used to minimize landfilling. The development of processes for these purposes places even greater demands on research and development. The same principles and methods developed for mining, ore dressing and metal refining processes can also be adapted for research and development work on processes for waste minimization. However, the problems encountered are much more complicated and less familiar, demanding more versatile and accurate tools and equipment. This paper presents principles, examples and some references of R & D work on processes for waste minimization.

Jan 1, 1992

By Li Cheng

The SKS copper smelting process was jointly developed by Shuikoushan Mining Corp. and ENFI (Beijing Central Engineering and Research Institute for Non-ferrous Metallurgical Industries) in China. It is a new bath copper concentrate smelting process with oxygen enriched air. The pilot plant testwork was completed successfully in 1993. SKS has demonstrated to be an advanced bottom blown smelting process. This technology got the First Class Prize of Scientific and Technological Progress awarded by CNNC (China National Non-ferrous Metal Industry Corp.) in 1994. The SKS process has significant capital and operating cost advantages. Its environmental and industrial safety and hygiene performance represents a substantial improvement when compared to conventional technologies. The technology has generated great interest in the Chinese metallurgical industry. Feasibility studies and basic designs have been carried out to incorporate in retrofit and green field smelter projects in China and abroad. This paper describes the history of the pilot plant operating data (50 tonnes dry feed/day), and discusses the features of the SKS technology, its application and possible future trends.

Jan 1, 1999

By Adele Garkida

Compacts of crushed waste window glass, fluorescent tubes, drinking glasses and laboratory glass wares were made at various proportions from 106 microns and minus 75 microns powders in combination with 5% bentonite as binder for each glass type, after several trials to determine compatibility of particle sizes. They were made using the uniaxial press at 10,000 psi and sintered at a temperature range of 700- 750oC. The results showed anisotropic shrinkage behavior for all the samples, exhibiting an axial shrinkage lower than the radial shrinkage. Sintered compact from waste drinking glass which comprised of 60% 106 microns and 40% minus 75 microns powders showed the least sintering shrinkage factor of 1.125, fused at 700oC and the highest shrinkage factor of 1.286 obtained at 750oC. This shrinkage behaviour connotes that sintering can be employed to utilize these waste glasses up to the maximum of 95% recycled glass content in ceramic tile production.

Jan 1, 2008

By P. G. Mason

The Getchell property was mined for oxidized gold ore by underground and open pit methods from 1936 to 194.5, by which time known oxide ores were mined out. From 1945 until 1967 sulfide ores were mined and roasted to improve gold recovery with varying degrees of success. In J 983 FRM Minerals, Inc. purchased the property. Since then they have carried out extensive geological exploration to define the size and character of the orebody. The sulfide ore is refractory to direct cyanidation, thus considerable metallurgical testing has been necessary to develop a suitable, cost effective process for its treatment. Wright Engineercs Limited have designed and engineered a gold extraction plant, which incorporates pressure oxidation to liberate the gold and? is scheduled to be commissioned early in 1989.

Jan 1, 1989

By Matti Hämäläinen

Outokumpu has developed a new chloride leaching process, HydroCopper?, for copper concentrates. The process utilizes the cupric ion as oxidant, which is able to dissolve chalcopyrite. After solution purification monovalent copper is precipitated as cuprous oxide, Cu2O, using sodium hydroxide. Copper product is produced from Cu2O by reduction, melting and casting. An essential part of the new process is chlor-alkali electrolysis, which regenerates the reagents used. All impurity metals are removed before Cu2O precipitation, because otherwise they would report to the copper product, impairing its quality. A multistage solution purification scheme has been developed consisting of firstly, chemical precipitation of impurity metals by pH increase, secondly, cementation of silver and thirdly, removal of trace multivalent ions using ion exchange. This paper describes the characteristics of solution purification in the HydroCopper? process based on the laboratory tests and pilot runs made by Outokumpu Research Oy.

Jan 1, 2003

By Corby G. Anderson

Antimony has been utilized by mankind for thousands of years. However, due to recent environmental concerns, antimony is often considered to be an impurity element, Since antimnoy is commonly found in precious metal refractory ore bodies, extraction is essential. The Sunshine Mine in Kellogg, Idaho has recovered antimony from its precious metal tetrahedrite deposits since the 1940&apos;s. A plant was initially constructed as a primary antimony source during World War II. This facility also decreased the downstream smelting penalty for the silver copper-lead concentrate and provided an industrial commodity from a potential environmental nuisance.&apos; This paper describes the Sunshine antimony processing- facility. Specifically, the relevant process chemistries involved in concentrate leaching, metal electrowinning, and sodium antimonate production will be discussed. In addition, ongoing areas of research to improve unit operations and treatments implemented to meet environmental&apos; discharge requirements will be covered.

Jan 1, 1992

By V. I. Lakshmanan

Whilst the prices of metals in nominal terms have largely remained static over the past forty years, in real terms, the primary metals industry receives very much less today for its products than in the past. Yet, it has largely managed to remain competitive, despite the fact that ore reserves are not only diminishing, but are of lower grade and higher complexity, and that there are much greater pressures on companies to be good environmental stewards. This paper examines how hydrometallurgical processing has shown itself to be highly innovative in order to remain viable both economically and environmentally. Aspects of process chemistry are discussed, and the lessons to be learned from having a good understanding of this chemistry are highlighted with reference to a number of case histories such as HPAL for nickel laterites, the Avmin/Chambishi Cosac Project, use of chloride chemistry for titanium extraction, and plant effluent treatment and recycle.

Jan 1, 2003