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By M S. Cassola

It’s expected that the world economy will face a stable and continuous growth in the demand of iron ore, reaching more than two billion tonnes per year within the next year. After decades exploiting resources with high content of iron ore, now the industry faces the challenge to exploit and beneficiate more complex ores.According to the industrial practice, the flotation technology is one of the most important and effective beneficiation processes to deal with low-grade iron ores around the world. However, even with this, it is still necessary to search for new processing routes or promote the optimisation of the existing circuits.The broad application of this technology is an outcome that deeply relies on the proper selection of flotation chemicals specifi cally designed for each system. New collectors are in continuous development as flotation performance significantly relies upon their optimisation.The reverse iron ore flotation in Brazil, mainly constituted by haematite and quartz, uses ether amines as collector for silica minerals and caustic corn starch as depressor for haematite. The process selectivity is highly impacted by the features of the etheramine, such as:• mono or di-etheramine,• neutralisation degree,• chain length,• branched or linear chain,• the flotation pH, and• the size distribution of the flotation feed.This paper describes the experience obtained from laboratory and industrial trials on different ores, conducted to improve the selectivity and recovery in the reverse iron ore flotation by selecting the required collector for low-grade ores.

Jul 11, 2011

By D Kentwell

For deposits where a full assay suite of elements/oxides is available and where several variables are critical to the evaluation of the deposit, it is desirable for the estimated block values of all elements/oxides to sum to 100 per cent of the weight per cent. This is difficult to achieve in practice and the estimation methods used need to be designed to minimise bias of the key elements/oxides by ensuring that block estimates are consistent with the individual assays and that the estimated totals are as close as possible to 100 per cent.This paper presents a case study of two domains within a magnetite hematite deposit, one with a high level of drilling classified as Measured and one with a lower density of drilling classified as Indicated. Several estimation methods were tested to evaluate their ability to maintain consistency of the proportions of each element/oxide and sum to 100 per cent. The following methods were evaluated: ordinary kriging, co-kriging, inverse distance and min/max autocorrelation factors (MAF) all as implemented in the Geovariances Isatis software.The comparisons showed that the MAF method produced the most robust estimates in terms of block totals and that grades and tonnages at the reporting cut-off were not significantly different between methods. At an individual block scale all methods produce artefacts that are less than desirable but can only be remedied by additional drilling.CITATION:Kentwell, D, 2015. Comparison of min/max autocorrelation factors, kriging, co-kriging and inverse distance block totals – a magnetite hematite case study, in Proceedings Iron Ore 2015, pp 465–474 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Guan-zhou Qiu, Shui-shi Liu, Yu-feng Guo, Tao Jiang

"The preparation of high-quality synthetic ruitle from electric furnace titanium slag was systematically investigated by activation roasting followed by acid leaching process. The results showed that impurities such as Ca and Mg in titanium slag can be effectively removed and TiO2 grade of the product was markedly improved by the process. High-quality synthetic rutile containing 88.54% TiO2, 0.42% (CaO+MgO) was obtained under the conditions that roasted with 7.5%(wt) H3PO4 at 1000 oC for 2h, followed by two-stage leaching in boiling dilute sulfuric acid for 2h. Mechanism studies showed that anosovite solid solution and silicate minerals were reacted with phosphoric acid in the roasting process. As a result, titanium components in titanium slag turned into rutile (TiO2) and impurities were transformed into acid-soluble phosphate and quartz.IntroductionWith the gradual depletion of natural rutile and the rapid development of titanium industry in China, the natural rutile reserves cannot satisfy the requirement for production of titanium pigment and titanium sponge. Ilmenite is, therefore, becoming main raw material for titanium industry. However, because of its low TiO2 grade, it generally requires preconcentration to titanium-rich material such as titanium slag or synthetic rutile [1-3].Ilmenite resources are extremely rich in Pan-xi area of China, which account for 90.54% of total ilmenite reserves in China [4]. The titanium slag produced by electric smelting of ilmenite concentrate has high contents of Ca and Mg, and is not suitable as a raw material for chloride process and titanium sponge production. Therefore, upgrading titanium slag to prepare raw material suitable for chloride process and titanium sponge production has important significance for the development of China's titanium industry."

Jan 1, 2011

By M A. Harrington-Baker, J M. Trudnowski

Sulfate-reducing bacteria (SRB) have the ability to immobilise dissolved metals by precipitating them as sulfides, provided that a favourable biochemical environment is created. Such an environment includes the presence of sulfate, anaerobic conditions and the availability of organic carbon. If such conditions are engineered within a reactive barrier or field-bioreactor, most metals can be effectively removed. To demonstrate this concept, three passive SRB field-bioreactors were constructed in 1998 at an abandoned mine site in the vicinity of Butte, Montana, USA to treat acid mine drainage with characteristic elevated concentration of metals and low pH. Performance of the field-bioreactors, using aqueous samples, was monitored over 32 months until the project was terminated, field-bioreactors were decommissioned and solid matrix sampling of the reactive matter was performed. The most important analytical results are presented in this paper together with conclusions regarding the appropriateness of the field-bioreactors construction features. Only Zn, Cu, and Cd were being removed as sulfides due to SRB activities. Changes in concentrations of other metals (Fe, Mn, Al, As), which do not necessarily precipitate as sulfide, seemed to be affected by SRB only in an indirect manner by responding to increased pH caused by SRB activity. An innovative cellular containment system used for placing organic matter worked very well in preventing settling of the organic matter and ensuring uniform flow of AMD throughout the entire cross-section of the organic carbon with no preferential flow paths This demonstration was funded by the US EPA and was jointly administered by the EPA and the US DOE under DOE contract number DE-AC22-96EW96405. The project was implemented by MSE Technology Applications, Inc, Butte, Montana, USA.

Jan 1, 2003

By E. Mata Robles

El presente texto refiere el proceso historiográfico de la planta concentradora Mahr Túnel ubicada en el valle del río Yauli a 3.4 kilómetros de las coordenadas de la carretera central del Perú. La planta se construyó en 1937 para el tratamiento de los minerales de plomo, cobre, zinc de la mina San Cristóbal. La operación de la planta comprende: recibo del mineral, planta de chancado, circuito de molienda, flotación Bulk cobre- plomo, flotación de zinc, espesamiento y flitrado, disposición de relaves. Los datos estadísticos de la planta se basaron en la capacidad, número de obreros, número de empleados, fuerza eléctrica, consumo de barras y bolas y consumo de reactivos. La seguridad y higiene de la planta concentradora mencionada cuenta con un Comité de seguridad conformado por un Superintendente de campo, ingeniero de Seguridad y el médico de campamento, así como para casos de accidentes es suministrado por el Hospital de Mahr Túnel.

Aug 20, 1963

By J. H. Morrish

"The delivered price of any mineral is the determining factor in converting untapped resources into economic resources. Transporting the minerals from the mine to the market plays a significant part in the total package. The expansion of the Western minerals industry in the last ten years has been paralleled by improved transportation systems to reduce cost, increase accessibility of resources and get the minerals to market in the shortest time possible. A review is made of developments, such as unit trains, complex multi-modal systems and containerized transport, over the last ten years, with specific movement outlined. The total transportation package of land transport, port and terminal facilities, and water transport, where needed, is stressed. As the volume of minerals movement expands, increasingly sophisticated and integrated transportation systems will have to be utilized. The development of solids pipelines and other possibilities is outlined."

Jan 1, 1973

By Charles R. Keyes

I. Introductory,.......... 185 II. Hypotheses oF the Origin of OzaRk Ores..... 186 1. General Considerations........ 186 2. Schmidt-Leonhard and Gage View...... 187 3. Jenney Opinion.......... 187 4. Posepny Idea,.......... 188 5. Winslow-Robertson Hypothesis....... 188 6. Branner Proposition......... 189 7. Keyes Statement.......... 189 8. Van Hise-Bain Theory........ 190 III. Requirements of an Adequate WoRking-Hypothesis,... 190 IV. GeneRal Geotectonics of the OzaRk Region.... 192 1. Salient Aspects.......... 192 2. Geologic Formations......... 192 3. Character of Faulting...192 4. Extent of Flexing......... 193 5. Unconformity Inequalities....195 6. Warping of Strata...195 V. Classes of Ore-Deposits... 196 VI. Vadose ORe-ConcentRation,........ 197 VII. GeogRaphic DistRibution of the Ore-Bodies,... 199 VIII. Relation of ORe-Deposit to Geologic Structure... 201 1. General Occurrence of Ore-Bodies in Basins.... 201 2. Deposits of the Central Missouri District..... 203 3. Deposits of the Southwestern Missouri District.... 203 4. Deposits of the Northern Arkansas District... 305 5. Deposits of the Southeastern Missouri District.... 206 6. Synclinal Ore-Deposits of Other Districts.....207 7. Significance of Ore-Troughs in Prospecting... 209 8. Origin of the so-called Synclines,...210 9. Significance of the Cross-Bars of Joplin..... 213 10. Relation of Ore-Run to Ancient Relief-Features,... 215 IX. Direction of GRound-Water Circulation..... 216 X. VeRtical Range of Workable Ore-Bodies,... 218 XI. Oscillation of Ground-WateR Level...... 219 XII. Relations of Ore-Bodies to Lithoclasic Features,.. 220 XIII. PRimaRy Source of Ore-Materials,...... 220 XIV. Zone of Ore-Enrichment,......... 222

Jan 1, 1910

By V. Sheikhzadeh, M. Saghaeian, R. Hejazi, A. Abazarpoor

"The morphology of pellet feed is known to influence several properties of iron ore pellets, including drop number, compression strength and reduction properties. The effect of grinding method on the particle size, specific surface area and particle shape of an iron ore concentrate has been studied. Grinding methods considered were ball mill and high pressure grinding rolls (HPGR). 5 different samples (Blaine= 1800, 1900, 2000, 2100 and 2200 cm2g-1) were used to compare the size, shape and specific surface of particles for each grinding methods. Particle size was meticulously examined by sieve analysis, laser sizing and image analysis. In samples ground by ball mill, it has been observed that the fraction of particles <10µm increases from 39% to 46% as the Blaine number increases from 1800 to 2200 cm2g-1. For HPGR samples, corresponding figures are 41% and 49% respectively. It is evident that for samples ground by HPGR, the fraction of fine particles is higher than that of those ground in the ball mill. To measure the specific surface area of particles, Blaine and BET were used. A higher real surface area was observed from HPGR treatment in comparison to ball mill grinding, provided by a higher porosity, cracks, roughness and new surfaces. Shape factor of particles was determined using three descriptors: circularity, roughness, and aspect ratio. It was also observed that particles produced by HPGR were more elongated, less circular, and rougher than those processed by the ball mill. 1. INTRODUCTION Particle size and shape are important parameters that can significantly affect mineral processing plants and pelletizing plant performances (Brozek and Surowiak, 2007). It has also been proposed that green pellet quality is directly related to the amount of fine particles in a pelletizing plant (Dwarapudi et al., 2008; Umadevi et al., 2008; Gul et al, 2014; Van der Meer, 2015). Particle size distribution and specific surface area (SSA) are also key factors that can control the quality of green and fired pellets. Processing circuits generally reduce the fines fraction to lower than the required specific surface area (SSA). It is therefore necessary to regrind concentrates to produce suitable pellet feed for further treatment in the balling and firing steps [1, 2]. Two main methods are used for re-grinding of concentrate; high pressure grinding rolls (HPGR) and ball mill. Given the different forces used to reduce size in these methods, it is expected the shape of particles will be different (Pourghahramani and Forssberg, 2005)."

Jan 1, 2018

By Panshi Xie, Yan Chen, Shaogang Wu, Yang Hang

In order to realize the intelligent mining of coal seam with large dip Angle, this paper adopts the methods of large proportion variable Angle loading threedimensional physical simulation experiment, numerical simulation and field measurement with digital twin technology. The hydraulic support with large dip Angle and large mining height is used as the prototype to design the physical entity model of 1:5 hydraulic support, combined with modeling and graphics rendering technology. Angle, displacement and load sensors were selected and placed to realize the data channel between the lower machine and the upper computer of the digital twin system, so that the position and load data of the physical entity model and the twin model of the laboratory hydraulic support could be shared in real time. Moreover, the multi-dimensional dynamic and static load transfer law and the position evolution characteristics of the support and surrounding rock under different inclination angles were analyzed. The results show that: with the increase of the Angle of the working face, first, the initial support force required by the support decreases, and the damage degree of the roof increases; When the roof is soft, the lifting operation can avoid the instability of the support to a certain extent. Second, under the action of positive pressure, the load of the top beam under different angles is balanced; Under the backpushing action, the load in the upper inclined area of the shield beam increases gradually, while the load in the lower inclined area decreases gradually. Under the lateral push, the load changes periodically, and the load in each cycle is increased compared with that in the previous cycle. Third, the numerical simulation analysis shows that the load on the lower bracket is less than that on the upper bracket, and the load on the bottom of all the columns is greater than that on the middle and upper brackets. In order to reduce the impact of the columns on the bottom plate or the base, it is necessary to improve the anti-subsidence ability of the base. Finally, according to the research results, the improvement and optimization measures of the support are put forward, and the field test shows that these measures effectively solve the problems of sinking, sliding and tipping of the support in the working face with large inclination Angle, and obtain good application results.

Feb 1, 2024

By Yingbao Yang, Jinyue Liu, Yonggang Wei, Bo Li

Due to the depletion of copper ore with high-grade and low impurity contents, the raw materials for copper smelting exhibit low copper contents and high impurities. High-impurity elements lead to the poor performance of the final copper product; thus, the removal of impurity elements during the oxygen-enriched copper smelting process is crucial. In this study, based on the production of high-grade matte, the occurrence states of impurity elements (such as As, Pb, and Zn) are analyzed in the input and output materials of the oxygen-enriched smelting process, and the phase transformation mechanisms of impurity elements are revealed during the oxygen-enriched smelting process. The effects of temperature, Fe/SiO2 ratio and oxygen concentration on the distribution behaviors of impurity elements in dust, slag and matte and the removal rates of impurity elements in matte are clarified. The results show that the impurity elements mainly exist as As4, As4S4, As2O3, Pb, PbS, PbO, Zn and ZnS in dust, as FeAsO4, As2O3, FeAsS, PbSiO3, Zn2SiO4 and ZnFe2O4 in slag, and as As, FeAsS, PbS, PbO and ZnS in matte. High smelting temperature, low Fe/SiO2 ratio and low oxygen concentration are beneficial for improving the matte grade and the removal rates of impurity elements Pb and Zn in matte. Low smelting temperature, low Fe/SiO2 ratio and high oxygen concentration are beneficial for removing impurity element As in matte.

Aug 8, 2023

Jan 1, 1969

By Edwin Itzig-Heine, Daniel Traylor, Bernard Tarralle, Michael McKenna

This paper discusses the challenges associated with the design and construction of a dual-cell, “figure eight” shaped shaft in saturated, soft ground for the Northeast Interceptor Sewer project in Los Angeles. The shaft will be excavated to a depth of41 m and used to launch two EPB TBMs. The specifications required concrete diaphragm walls, embedded below the shaft invert, and a grout curtain beneath the wall. To control water pressure and basal stability without a grout curtain, wall panels were embedded deeper than required into a stiff, cohesive deposit. Details of wall panel excavation using a Hydrofraise are presented.

Jan 1, 2003

By O. A. Bascur

Several new hydrometallurgical plants have been built in the past years, new processes and equipment as well as advanced process control systems are being used to deal with the increasing requirements of safety, quality and production. Plant Information Management Systems are now being recognized as a key infrastructure component of the plant, giving the management, the operators, process engineers, finance, maintenance, and regulatory agencies an integrated view of the operation and providing the links for the (increasingly) multidisciplinary organization. This paper reviews several implementations of Plant Information Systems; real time performance management infrastructure examples are reviewed as a key component of business strategies, such as Mine to Port Planning and Supervision, Metallurgical Mass Balances, Solvent Extraction Composition Statistical Process Control, methods to minimize organic losses, reduce variable costs and to improve metal extraction. Several examples are provided to illustrate how companies are using the real time and historical information from assets and metallurgical processes to enable and empower people to improve the operations quality, safety and throughput, as well as continuous improvement and innovation initiatives.

Jan 1, 2007

By Pedro Cunha Alves, Wagner Viana Bielefeldt, Vinicius Cardoso da Rocha, Julio Aníbal Morales Pereira, Antônio Cezar Faria Vilela

Consideráveis esforços vêm sendo realizados para aumentar o desempenho das operações metalúrgicas e a qualidade do aço produzido. Nesse sentido, o papel das escórias no processamento do aço tem se tornado de muita importância. Com o objetivo da otimização das escórias, numerosos estudos têm sido conduzidos para uma melhor compreensão do efeito da composição química e demais propriedades da escória sobre a viscosidade, bem como, sua influência sobre o controle da limpeza inclusionária. Também se tem observado uma evolução das técnicas experimentais de laboratório que são empregadas para a investigação estrutural e medidas das propriedades físicas das escórias. Essa evolução e investigação são fundamentais, inclusive, para o ambiente prático da indústria do aço.

Oct 1, 2019

By N. J. Bunce, B. Vollick, A. F. Souza, D. Bejan, P. Maharaj, C. Shamshoom

"Copper electrodeposition from synthetic and authentic acid mine drainage (AMD) is inhibited by ferric iron (Fe(III)), through re-oxidation of copper. Polarization to –2.5 V versus standard hydrogen electrode prevents the dissolution of predeposited copper from the cathode. Above pH 1, copper deposition is independent of Fe(III) concentration to approximately 25 g/L. Fe(III) is reduced to ferrous iron (Fe(II)), with a high combined current efficiency for iron and copper reduction. In a divided cell, the conversion of Fe(III) to Fe(II) is almost quantitative, with efficient transfer of acidity from catholyte to anolyte. Prospects for developing electrochemical technology for complete remediation of AMD are discussed.RÉSUMÉ En raison de la réoxydation du cuivre, le fer ferrique (Fe(III)) nuit à l’électrodéposition du cuivre à partir de drainage minier acide (DMA) véritable et synthétique. Une polarisation à -2,5 V par rapport à l’électrode standard d’hydrogène empêche la dissolution du cuivre déjà déposé de la cathode. À un pH supérieur à 1, la déposition du cuivre est indépendante de la concentration en Fe(III) jusqu’à environ 25 g/L. Le fer ferrique est réduit en fer ferreux (Fe(II)) avec une efficacité combinée élevée pour la réduction du fer et du cuivre. Dans une cellule divisée, la conversion de Fe(III) en Fe(II) est près de la quantité théorique, avec un transfert efficient de l’acidité de catholyte à anolyte. Les perspectives de développement d’une technologie électrochimique pour la remédiation complète du DMA sont discutées."

Jan 1, 2016

By R. Maddin

IN analyzing the relation between the orientation of new grains and that of the deformed matrix of axially extended and recrystallized single crystals of face-centered cubic metals, a two-stage rotation process" is generally used where the first rotation is made in order to account for an "adjustment of orientation to the environment of strain."&apos; It has been argued that in spite of the difference of orientation, which may amount to as much as 12" (in a brass),&apos; between the octahedral plane as observed in the parent lattice and in the recrystallized grain, it is believed to be a common plane in the sense that it constituted the nucleus in the parent strained crystal from which the new grain grew.&apos; A possible source of the deviation in orientations of a common pole in the new grain and that of the deformed single crystal matrix from which it has grown may be found in the distribution of strain resulting from the plastic deformation. It might be expected in view of the incongruent nature of shear&apos; that the perfection of the octahedral plane along which glide has occurred is disrupted and that this disruption constitutes the strain from which nuclei of new grains can grow during recrystallization. Evidence for the existence of strain along glide planes was first detected by Taylor" in 1927 and substantiated by Collins and Mathewson&apos; in 1940. In their investigations, however, the deformed single crystalline specimens (aluminum) were cut mechanically along the glide planes followed by mechanical polishing. X-ray exposures (glancing angle) of only 8 min with filtered radiation were used. It was later shown&apos; that this type of surface preparation did not remove with all certainty the mechanically disturbed surface. It was felt that a re-investigation of this phenomenon using more refined techniques might reveal a more correct extent of the strain resulting from the deformation which might correlate the deviation of the common pole of the recrystallized grain with the acting slip plane of the matrix crystal. In accordance with these thoughts, a single crystal of a brass (70/30 nominal composition) M in. in diam x 5 in. long, tapered as in previous experiments,&apos; was extended and carefully documented with respect to elongation and shear. Disks about % in. thick paralle&apos;l to the primary slip planes were cut from the specimen by means of an etch cutter." These disks represented volumes of the specimen which had been extended 0, 5, 10, 15, and 20 pct. Copper Ka monochromatic radiation was obtained by reflecting 35,000 v copper radiation from the c-cleavage face of a pentaerythritol crystal. The monochromatic radiation was collimated and led on to the disk set at the proper 0 angle for reflection from the primary (111) planes. The monochromatic beam was aligned in a plane containing the active slip direction. Following a 10 hr exposure at the theoretical Bragg angle, the disk was reset at 0 + 1°, 0 — 1", 0 + 2", 0 — 2", etc., until no Bragg reflection was obtained. The disk was then rotated 90" about its polar axis, and the same X-ray procedure was used. The results are shown in Table I. It may be seen from the results in Table I that the plastic deformation (20 pct elongation) produces fragments of the glide plane which are rotated or tilted as much as 25 " from the normal position on a purely block slip model. In addition to the large variation in 0 angle in the slip direction, there is a variation in 0 as much as 20" in the direction at right angles to the direction of slip, i.e., <110>. In view of the results shown, it may now be argued that the strain distribution finds its origin in the incongruent nature of the slip process.&apos; The use of the two-stage rotation process seems valid in attempting to explain the relation between the orientation of recrystallized grains and the matrix from which they have grown. Acknowledgment This work was sponsored by the ONR under Contract Number N6 onr 234-21 ONR 031-383. The author would like to thank N. K. Chen for reading and correcting the manuscript. References &apos;R. Maddin, C. H. Mathewson, and W. R. Hibbard, Jr.: The Origin of Annealing Twins. Trans. AIME (1949) 185, p. 655; Journal of Metals (September 1949). &apos;J. A. Collins and C. H. Mathewson: Plastic Deformation and Recrystallization of Aluminum Single Crystals. Trans. AIME (1940) 137, p. 150. eN. K. Chen and C. H. Mathewson: Recrystallization of Aluminum Single Crystals After Plastic Extension. Unpublished. 4 C. H. Mathewson: Structural Premises of Strain Hardening and Recrystallization. Trans. A.S.M. (1944) 38. :&apos;C. H. Mathewson: Critical Shear Stress and Incongruent Shear in Plastic Deformation. Trans. Conn. Acad. of Arts and Science, (1951) 38, p. 213. "G. I. Taylor: Resistance to Shear in Metal Crystals, Cohesion and Related Problems. Faraday Soc. (1927) 121. &apos;R. Maddin and W. R. Hibbard, Jr.: Some Observations in the Structure of Alpha Brass After Cutting and Polishing. Trans. AIME (1949) 185, p. 700; Journal of Metals (October 1949). &apos;R. Maddin and W. R. Asher: Apparatus for Cutting Metals Strain-Free. Review of Scientific Instruments (1950) 21, p. 881.

Jan 1, 1953

Jan 1, 1929

By Doris M. Hyde

The Bahama&apos;s petroleum-dominated minerals sector constricted again in 1985. The declines were mostly the result of a soft market demand for crude oil and petroleum products. In early 1984, it was a growing unprofitability that prompted Charter Oil Co. to cease using the 350,000-barrel-per-day Bahamas Oil Refining Co. facility that it jointly owns with Chevron Oil Bahamas Ltd. After midyear 1985, because of poor petroleum economics, Chevron announced it would close the refinery, leaving only a maintenance crew. In 1984, the refinery exported less than 26 million barrels of petroleum products. Chevron&apos;s throughput was reported as averaging about 8,000 barrels per day at the time of the announcement. The crude oil transshipment terminal also registered declining activity and financial losses in 1984 and 1985. Transshipments of petroleum in 1985 amounted to about 100,000 barrels per day, one-half as much as in 1982.

Jan 1, 1987

For more than 15 years after the Northparkes orebodies were first discovered in 1976, the project was delayed by the need to find an economic way of mining the low-grade E26 deposit. The decision to use a low-cost block caving method to mine the orebody was made in the early-1990s; but the project&apos;s future did not solidify until 1993 when a radical new approach was adopted which sought to integrate business imperatives with technology and organisation strategies. The approach led to the establishment of a strategic vision which tied together all the components that could have a major impact on the project, to provide a framework for guiding strategic choices. The strategic vision strived to break away from the old rules of how mines are organised and operated; and involved finding imaginative new ways to radically redesign mining processes to achieve quantum leaps in performance.

Jan 1, 1997

By E. G. Davis

Under a memorandum of agreement with Reynolds Metals Co., Richmond, VA, the Bureau of Mines studied the problem of corundum formation on refractory linings in aluminum recycling furnaces. A laboratory test was developed for evaluating refractories in contact with molten recycled aluminum and identifying the mechanism of corundum formation. A test apparatus was designed and constructed to evaluate the performance of refractory samples. Corundum mechanism formation studies indicated that corundum formed on refractories when there is metal penetration. Once corundum forms, it acts as a wick allowing the molten aluminum to move to the surface where it is oxidized, thus causing further growth of the corundum. Phosphoric acid treatment or a spinel mortar coating prevented corundum formation on the 70-and 90-pct-A1203 refractories.

Jan 1, 1988