Search Documents

By Eduard Stefanescu, James M. Mwase, Egon Sehner, Stoyan Gaydardzhiev

"The study is focused on investigating the production of synthetic rutile of 95% purity or higher from a Norwegian ilmenite ore concentrate. This was to be achieved using a sequential process involving oxidative-reductive roasting at 975°C, followed by magnetic separation to further concentrate the sample and finally leaching with 20% HCl to remove mostly Fe-based impurities leaving behind synthetic rutile. The key process parameters considered were roasting time (1 and 2 hrs), leaching temperature (100, 125 and 145°C), pulp density (15 and 25wt%) and leaching time (3 and 6 hrs). The option of directly leaching the concentrate without pre-treatment was also evaluated. Test work was conducted using samples screened to a size fraction of 105-212 µm. Samples were leached in a 1 L glass autoclave. The reactor was hermetically sealed and thus the resulting pressure was not controlled but was dependent on the process temperature. The product from leaching was calcined and analysed via XRD and SEM to determine the purity of the product. The magnetic separation step was found to be ineffective and discontinued early in the study. Thus far a product with 97% synthetic rutile purity as analysed by SEM has been produced by directly leaching the concentrate at a temperature of 145°C, pulp density of 25wt% and leaching time of 6 hrs.INTRODUCTION The study investigates the use of a process route comprising oxidative-reductive roasting, followed by magnetic separation and then hydrochloric acid leaching and calcination to produce synthetic rutile from ilmenite concentrate. The grade of synthetic rutile produced should be suitable for chlorination to produce pigment grade TiO2. Hence the proposed process should produce a product consisting of no less than 95% synthetic rutile. Additionally, the product should have no more than 1.5wt% combined content of CaO and MgO (Zhang et al., 2011) as they tend to form high-boiling-point chloride leading to the malfunctioning of fluidized bed chlorinator (Cardarelli, 2008). Finally the product should have no more than 2.1wt% of Fe2O3."

Jan 1, 2018

By Francisco Grimaldo Zapata

Las estrategias son las únicas formas sostenibles de crear valor en las empresas. Sin embargo, los resultados en gestión determinaron algunos fracasos en su aplicación. En este sentido, es necesario plantear una gestión que permita mecanismos de reacción más rápidos ante los cambios, priorizando la capacidad de ejecución del la estratategia que la formulación de esta en sí misma. Por ello, el presente texto señala la aplicación de una nueva estrategia que busca el cambio de comportamiento en una organización antigua como es la unidad minera Cerro de Pasco. Las nuevas estrategias se aplican a la gestión de seguridad y medio ambiente, en el que se mejoran los procesos, se incrementa la productividad, se crea una política de prevención, y existe una mejor utilización de todos los recursos. Asimismo se reducen los costos y se le da más valor a la empresa para que pueda contrarrestar las fluctuaciones de los precios de los metales.

Sep 13, 2001

By Hans Smit

The face of mining as we know is changing as mining companies all over the globe realize the reality of accessing the vast mineral wealth contained on, and under, our ocean floors. With some land based mineral deposits being fully exploited across the world, deep sea mining is set to revolutionize global approaches to the search for precious metals and other sought after minerals. Previously, the financial and technological implications of deep sea mining outweighed the benefits of access to the mineral rich deposits identified all around the world. The process of marine diamond mining off the west coast of southern Africa started in the late 1950s, and subsequently continued by De Beers to the present day, has proven to be an excellent proving ground for the development of technology and mining systems that ensure a sustainable and financially viable business.

Jan 1, 2011

By Carrie Smith

The 2025 Women in Mining USA National Conference, held April 15-18 at the Grand Hyatt Riverwalk in San Antonio, TX, brought together hundreds of professionals for a fourday event focused on empowering women and creating space for all individuals in the industry. Under the theme “Empowering the Future of Mining,” the conference served as a dynamic platform for professional development, knowledge-sharing and cross-sector collaboration. Organized by Women in Mining USA (WIM USA), whose mission is to foster equity, sustainability and leadership in mining, the event featured an extensive agenda including workshops, keynote speeches, panel discussions and networking opportunities. Attendees ranged from industry veterans to emerging professionals and students, united by a shared commitment to progress within one of the world’s most essential and traditionally maledominated sectors.

Jun 1, 2025

The paper will cover the basic reasons for alkaline leaching, a brief description of the circuit and the reasons for the flowsheet used. Changes made to the flowsheet, including the use of mechanical agitation of pachuca slurry, the use of oxygen and its effect on extraction, the use of lime and its effect on process economy, and the environment, will be described. A brief description of a unique semi-autogenous mill and future circuit changes will be included.

Jan 1, 1979

By Agne Rustan

The 9th International Symposium on Rock Fragmentation by Blasting was held in the Granada Conference Centre, Granada, Spain from the 14th - 17th September 2009. The Symposium was preceded by a 1 ½ day Workshop on “Vibrations from Blasting” organized by the initiator Dr. Alex Spathis and his colleague M. J. Noy, both employed at Orica Mining, Australia. Prof. Josè Sanchidrian at the “Universidad Politécnic de Madrid” in Madrid, Spain was the main organizer for both the Workshop and the Symposium. A record number of participants came (292) from a record number of countries (41). There were a total of 14 papers in the Vibrations from Blasting Seminar and 96 papers and 2 Keynote Addresses in the Fragblast 9 Symposium itself. The aim with this paper is to present some results from Fragblast 9 which are of interest for a large target group. One very important result from the Fragblast 9 meeting was that it was decided there that Fragblast 10 will be held in November 2012 New Delhi India.

Jan 1, 2009

Alcoa of Australia's Western Australian bauxite mining operations in the Darling Ranges, southeast of Perth, present major challenges in the control of air blast. The close proximity of rural communities and the face profile make the traditional methods of air blast control difficult.An extensive blast noise monitoring programme has been established. The development of a computerised blast noise prediction model and the establishment of a radiosonde weather balloon facility have reduced blast induced complaints by a factor of ten.The meteorological factors affecting blast noise transmission are discussed and examples are given of adverse weather conditions for the southwest region of Western Australia.

Jan 1, 1983

By M. G. Stamatakis, C. Zagouroglou, C. Helvaci, J. Kanaris

"Abstract -Borate minerals, such as colemanite, ulexite and borax, have been reported in Tertiary continental basins of West Anatolia, Turkey, and Samos Island, Greece.Tuffaceous rocks interbedded with the borates are rich in authigenic silicate minerals such as zeolites, potassium feldspar and opal-CT, all of which have a genetic association with the borates. Chemical analyses of the tuffaceous rocks show variation in major elements due to the varying percentage of carbonaceous, detrital, and volcanic derived material.The volcanic activity in the vicinity of each particular lacustrine basin created ion-rich fluids from which a series of borates were precipitated under arid climate. Additionally, the saline-alkaline character of these fluids was responsible for the diagenesis of the silicic glass of the tuffaceous rocks, altering them to silicates and silica polymorphs."

Jan 1, 1993

By Calvin C. Brown

A university is a place to build minds and develop leaders. It provides the tools necessary for the development of new ideas which come from the inquisitive mind and is one of the stepping stones to management responsibilities for the truly ambitious. However, it is not always a financially sound investment! Lately, there have been several articles published on the economic advantages of a college education. These articles tend to average wages together according to education and years of service. Their tabulations generally include the chairman of the board, various vice presidents and plant managers and do not reflect the achievement of the average graduate. They consistently fail to include an analysis of the investment a college education requires. In reality, the bright high school graduate would make more real money over a 20-year period if he went directly to work "on the hill" than he would if he graduated from college. Furthermore, he would find little difference between his wages and those of the college graduate in the period from 20-30 years after high school graduation.

Jan 1, 1971

By Don M. Jackson, Robert W. Howard

Techniques for the epilaxial growth of single -crystal silicon carbide films on silicon were developed. The vapor-phase decomposition and bydrogen reduction of silicon tetrachloride (SiC14) and Propane (C3H8) resulted in clear films of silicon carbide, lip to seveval microns in thickness. The growth took place in a horizontal . silicon epilaxial reactor at 1100°C (pyrometer) at a rate of- 3000Å per minute. Electron diffraction and X-ray diffraction studies demonstrated that the films were single-cyrstal, ß -phase, or cubic silicon carbide. SiO2 film were used to mask areas of the silicon sur-lace in order that the silicon carbide might be grown in controlled geometries. Both n- and p-type films were grown on p-type silicon waters.. Heavily doped silicon films of the same conductivity type as the silicon carbide films were deposited over the silicon carbide in order to affect better probe contact to the structures. when n-type silicon carbide mesas were grown on p-type silicon substrates the de vollage-current relationships between films and substrates were that of junction diodes. These diodes showed a sensitivity to while light ill that the incident light increased forward- and reverse-satro,ation currents, P-type silicon carbide mesas grown on p-type silicon were ohmic rather than rectifying in their voltage -current relationship. No conclusions could he reached concerning heterojunc-tiou rectification in the structure. SILICON carbide is a semiconductor with many interesting properties. It decomposes at temperatures above 2200°C.1 It occurs in two general crys-tallographic forms—hexagonal (a Sic) and cubic (ß Sic)—with the cubic form having a forbidden-gap energy of 2.32 ev and the hexagonal form (specifically the 6H polytype) a gap energy of 2.86 ev.3 It behaves as an extrinsic semiconductor at temperatures approaching 5003C. It has been shown to have a high resistance to radiation damage4 and p-n junctions formed in Sic have been shown to radiate visible light under forward- or reverse-bias conditions. Epitaxial silicon carbide on silicon carbide has been successfully grown through the use of a variety of techniques, such as gaseous cracking of SiCL4 and CC4, nearly all of which require a deposition temperature above 1500°C.6 This paper will cover very recent work on the gas-phase deposition of highly ordered films of silicon carbide on high-quality silicon single-crystal substrates. The films have been shown to ex- hibit junction-rectification properties when geometrically isolated regions are electrically biased with reference to the silicon substrate. There will be no discussion of the mechanism of heterojunction rectification, but the methods of film fabrication, geometry control, and structural evaluations will be covered in detail. Electron diffraction, X-ray diffraction, and diode electrical properties were used to characterize the films and the junctions. GAS-PHASE DEPOSITION OF Sic The techniques for the deposition of silicon carbide films were a logical outgrowth of the standard silicon epitaxial process. The major premise followed was that, for any film to nucleate in an ordered fashion where there is considerable mismatch in lattice parameters (in this case 22 pct), an extremely clean, damage-free substrate surface must be presented to the gas stream. Thus a standard gas-phase HCl etching step was used to prepare the substrates for growth. A minimum of 5 µ of substrate-surface material was removed prior to the deposition of Sic overgrowth films. The techniques used for growing silicon carbide films were those of growing silicon alone, with the added injection of a hydrocarbon gas into the hydrogen and silicon tetrachloride gas stream. The hydrocarbon gases used thus far have been research-grade (99.99 pct) methane (CH4) and propane (C3H8). Propane ultimately gave the best results. The gas flows were controlled through a panel shown schematically in Fig. 1. A hydrogen main stream of 30 liters per min passed through the horizontal quartz-tube epitaxial reactor, while SiC14, C3H8, HC1, and doping gases were injected as side streams. The

Jan 1, 1965

By M. S. Burton, G. V. Smith, A. Rosen

The kinetics of re crystallization and the effect of recovery on recrystallization of pure iron were investigated within the temperature range of 517" to 632 OC. Grain growth and activation energies were also studied. Two stages can be distinguished during recrystallization; the first is gvowth-controlled and the second is nucleation-controlled. The extent to which the first stage succeeds before the second stage begins depends on both temperature of recrystallization and temperature of recovery. The softening of cold-worked metals and alloys due to transformation of the deformed crystals to strain-free equiaxed grains during annealing is well-known, and early inestiators established that recrystallization kinetics is strongly influenced by minute quantities of impurities. Generally, it is believed that impurities decrease the rate of recrystallization and the rate of grain growth. To understand the basic phenomena of recrystallization, investigations should be on pure materials. Most of the research on high-purity materials has been on metals having the fee Bcc materials, and especially high-purity iron, have been studied only in recent years. It is known that recovery may influence recrystalliation;" however, no general description of the influence, applicable to all materials, has been presented. This paper presents results of a study of the recrystallization kinetics of high-purity iron, after 60 pct cold deformation by drawing, with particular reference to the influence of recovery on the rates of recrystallization and grain growth. From observations of these rates, conclusions are drawn concerning nucleation. MATERIAL AND EXPERIMENTAL PROCEDURE Preparation of Material. High-purity iron, prepared by zone refining of vacuum-melted electroiytic iron at Battelle Memorial Institute under sponsorship of the American Iron and Steel Institute, was used in this study. Table I gives the reported chemical analysis of the material, taken at a point near the last molten zone and thereby rep- resenting the maximum impurity level for the entire bar. Prismatic specimens, approximately 10 x 10 X 50 mm, were sawed from the 50-mm-diam bar, perpendicular to the zone-refining direction, and turned to cylindrical shape. These specimens were sealed in quartz capsules under vacuum, approximately 10"e mm Hg, austenitized at 930° C for 15 min, slowly cooled, removed from the capsules, and cold-worked in air by swaging to approximately 20-pct reduction of area. The encapsulating, austenitizing, and swaging operations were repeated two additional times, after which the samples were encapsulated, austenitized, and cold-drawn to 60-pct reduction of area. A further vacuum anneal at 630°C for 120 min and cold drawing to 60-pct reduction of area produced wire 2.8 mm in diameter. The drawn wire was electropolished to remove deformed material on the surface, after which it was sawed into 4-mm-long specimens for the recrystallization study. Microscopical examination before the final cold reduction revealed equiaxed grain structure with very fine grains in a thin layer near the surfaces of the specimen and nearly uniform ASTM 3-4 grain size in the center. Recrystallization Heat Treatment. a) Direct Recrystallization of Cold-Worked The 60 pct cold drawn iron specimens were recrystallized at five temperatures, 517, 556, 590°, 612, and 632C, in a lead bath covered with graphite (the temperature was controlled to 1°C). Specimens were treated for twelve different times at each temperature, and all were water-quenched after heat &eatment. b) Recrystallization Following Preliminary Recovery Heat Treatment. After cold working, specimens were sealed into quartz capsules under vacuum, 105 mm Hg, and recovery-annealed at 362", 400", and 440°C for 20 hr prior to recrystallization. No evidence of recrystallization was found

Jan 1, 1964

By D. Morin

A general study of gold refractory arsenopyrite-pyrite concentrate bioleaching has been carried out including two continuous bioleach testworks at different sizes, namely one at a laboratory scale with a 100 I unit at a 2 kg/d dry solid flowrate and the other at a pilot scale at a 100 kg/d dry solid flowrate. Both tests show a 80% bioleaching of arsenopyrite in about four days of treatment and with the same kinetic. Pyrrhotite is attacked at the earlier stage of the bioleaching but pyrite remains unaffected. The weak potential of oxidation associated with the decomposition of arsenopyrite and the abundance of arsenite leads to a high grade of elemental sulfur in the bioresidue which consumes the major part of the cyanide during the gold recovery. Furthermore. the arsenite and ferrous produced in solution have to be oxidized to obtain a stable precipitate in the waste products and as outlined in previous works of other authors on this subject the addition of iron to obtain a Fe/As molar ratio at least above 3 is necessary. The agitation equipment used in the pilot unit allowed an optimization study calculation for scaling-up the design and power requirements of an industrial installation. For the pretreatment of a gold refractory As high-graded concentrate the reagent cost has the greatest part in the operating cost of the biooxidation step due to the necessary retreatment of the biosolution. In that conditions the power cost is quite marginal. actually it is significant for the treatment of pure pyrite.

Jan 1, 1991

By J. A. Botín

Mining investment decisions are difficult since decision analysis is often based on scarce information. The sources of uncertainty in large mining investment projects are particularly numerous and are present in all evaluation stages. Hence the feasibility decision for projects of this nature will largely depend on how well these sources of uncertainty are managed to achieve bankable risk levels. The risk associated to the construction stages of a mining project is particularly difficult to quantify, mainly because the large number of variables affecting constructive yields, and the complex interactions among constructive resources. This investigation focuses on developing quantitative simulation models and tools to increase the value of a mining project by means of an optimization of the preproduction equipment fleet. The models were validated through their application in the Chuquicamata Underground Mining Project.

Feb 23, 2014

By AIME AIME

PETROLEUM technology was the sole subject of discussion at the meeting of the Petroleum Division at the Baker Hotel, Dallas, Texas, Oct. 6-7, except for the brief talks by President Becket and Secretary Parsons at the dinner on Friday evening. Even on this occasion, following the scheduled official features, it was in order to talk "shop." W. E. Wrather and E. A. Stephenson, respectively Chairman and Secretary of the Division, had planned for a meeting of this nature and by preference, apparently, the 122 who registered fell in with the scheme wholeheartedly. Not because the competent local committee had not provided for it, but by choice, the members just did not sign up for entertainment or field trips, but did attend largely the three technical sessions and engage in earnest discussion of the approximately dozen excellent papers. In this connection, and without question, the high lights of the meeting were the papers by Morris Muskat and R. D. Wyckoff, and Prof. W. K. Lewis. The former, entitled, "A Theoretical Analysis of Waterflooding Networks," had been entirely demathematized by the authors for presentation at this and the Los Angeles meetings; the author of the latter, which was on the "Physical-chemical Relationships of Hydrocarbon Gas-liquid Mixtures at High Pres¬sures," had airplaned to Dallas in the company of Dr. H. D. Wilde from Chicago in order to present his paper at the final session on Saturday morning.

Jan 1, 1933

By L. F. Pease, J. H. Brophy

A phase diagram for the Ta-Zr system is presented. The system is of the minimum-melting point type with the 0-zirconium phase decomposing monotectoidally at 785°C and 95.5 at. pct Zr. The minimum solidus temperature is 1875°C and the temperature of the top of the monotectoid loop is 1775°C. Techniques employed included X-ray diffraction and fluorescmce, electron microprobe analyses, diffusion couples, metallography, and melting-point measurements. Errors due to interstitial solutes and in melting observations are particularly common in this system, and their occurrence is discussed. SEVERAL versions of the Ta-Zr phase diagram have been reported in the literature.lm7 Williams et al.' report a diagram of the minimum-melting point type with a monotectoid reaction at 800°C and 12 wt pct Ta. The minimum in the solidus occurs at 1820°C and 25 wt pct Ta, while the top of the monotectoid gap is located at 1780°C and 80 wt pct Ta. The experimental techniques employed were metallography, electrical resistance variation with temperature, dilatometry, X-ray diffraction, and direct observation of melting by the technique of Pirani and ~lterthum.' Experience in the Nb-Zr phase diagram has shown that small changes in the interstitial content can cause large shifts in the positions of the phase boundaries. Small amounts of inter -stitials can cause similar changes in the Ta-Zr system and may be responsible for the wide variations in the phase diagrams previously reported.'-' The authors15 have found that alloys containing 0.75 wt pct 0 and 1.0 wt pct Ni with tantalum contents from 19 to 85 at. pct often contain a lamellar or cellular precipitate after annealing above 1400°C. This precipitate is very similar to that reported by pollack,12 Ralls," and Donlevy17 for the Ni-Zr system. In the present investigation, a wider variety of experimental techniques and improved alloy purity were applied to the resolution of errors in diagrams for this system as they now appear in the literature. New results have been obtained in the areas of alloy homogeneity and purity. Errors in the common techniques of direct melting observation in binary alloys have been demonstrated. In the commercially important high-tantalum region, the more accurate metallographic method of solidus determination has been employed. EXPERIMENTAL PROCEDURE Nominal analyses of the materials employed are given in Table I. The zirconium was low hafnium reactor grade iodide crystal bar, and the tantalum was in the form of high-purity sheet. Powders were impossible to use because of gas content. Alloys were melted on a water-cooled copper hearth, with a thoriated tungsten-tipped nonconsumable electrode in 2/3 atm of Zr "gettered" argon. Alloys were

Jan 1, 1963

For small particles of niekel flotation eoncentrate (av. size 50 pm) the predominant heat transfer mechanism under suspension smelting conditions, prior to ignition, is conduction from the gas and not radiation from nearby hot bodies. Results of laboratory tests using gas temperatures 380-700°C and furnace wall temperatures 380-1100°C were in accord with heat transfer theory. In practieal flash smelters earlier ignition, and hence better utilization of the space in the shaft, would result from introduetion at the top of the shaft of gases hotter than the ignition temperature of 500-600°C.

Jan 1, 1979

By John E. Kinnison

The Mission mine, located in southern Arizona near Tucson, is a recently developed open pit which produces 15,000 tons per day of copper ore. The mine lies on a wide and gently sloping bajada sweeping northeasterly from the Sierrita mountains. It derives its name from the nearby Mission San Xavier del Bac, built circa 1700. The ore body is everywhere covered by about 200 feet of alluvium, as are the adjacent Pima and Palo Verde mines. The geology of the Mission deposit is known principally through the study of diamond drill holes spaced 150 to 300 feet apart. The open pit is in an infant stage and has not yet revealed much of the deposit, although information obtained there by the operating staff, and from a few thousand feet of exploratory underground workings, has added significantly to the general fund of knowledge. Permission to publish was granted by the American Smelting and Refining Company. I am indebted to Kenyon Richard and J. H. Courtright for criticism of this paper and for their direction during the several years in which I studied the Mission deposit. Acknowledgment is given to consultant in petrography, Robert L. DuBois of the University of Arizona. The only previous publication pertaining directly to the geology of file Mission deposit appeared in 1959 (Richard and Courtright), and may not be everywhere readily available. Cooper (1960) has published a short paper on the district

Jan 1, 1963

By Larry G. Stolarczyk

An underground medium frequency radio communications system has been developed and demonstrated in both coal and metal/non metal mines. The principal advantage of the system are its low cost, ease of installation and the ability to provide radio communications to any vehicle or roving miner in the underground mine. The system provides high quality radio coverage in work areas and along manways with existing "wireplant" conductors. The conductors include AC power cable, telephone cable, metal water and high pressure air pipes, etc. The measured communications range from the base station to mobile transceiver exceeded 12,500 ft without the use of repeaters. A cost/benefit analysis shows that the initial cost of the equipment can be returned 2-6 times in the first year. The mine productivity increases by approx. 13 percent.

By W. Abdellah

The purpose of this paper is to establish a qualitative method to estimate the risk level (e.g. rating and ranking) resulting from mining activity. Risk is the product of two factors: probability of failure and cost of consequences. A resultant assessment scale matrix is then used to assign a risk index value which is directly proportional to the potential for excavation instability. A case study, the No. 1 Shear East orebody at Vale?s Garson Mine in Sudbury, Ontario will be examined. A three-dimensional, elastoplastic, finite difference model (FLAC 3D) is presented for a mine development intersection situated 1.5 km below ground surface. The developed assessment scale matrix is used to estimate risk index for intersection (2981) located on 5000 level. The results are presented and categorized with respect to risk-index value, probability of instability, cost of consequence, and mining stage.

Jan 1, 2014

By Howard N. Egan

The importance of coal as the major energy source has led to wider interest in the recovery of waste coal fines as a usable product. An additional incentive for fine coal recovery has been the increased emphasis on environ- mental pollution control and conservation of the nation's natural resources, Accordingly, a series of studies and tests were performed to investigate the feasibility of the recovery, concentration, balling and pelletizing of coal fines as a marketable adjunct to existing mining and beneficiation operations. These studies were conducted at the existing operations of the Eastern Coal Corporation at Stone, Kentucky, and the Metallurgical Laboratory of Arthur G. McKee & Company in Cleveland, Ohio. The purpose of the investigations was to recover the fines from the effluent waste waters of an existing preparation plant and transform them into a high carbon, low sulfur and ash product capable of being handled with a minimum of degradation and dusting problems. The fines were relatively high in ash content prior to processing, and flotation pretreatment served a combined function of beneficiation, recovery and water clarification, The minus 28 mesh coal concentrate containing 40 to 45 percent minus 325 mesh size material had an ash content varying between 5 and 7 percent and a sulfur content of less than 0.5 percent. Chemical and size analyses of the effluent and concentrated fines are presented in Table I for comparison.

Jan 1, 1967