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By D. A. Norrgran, J. A. Wernham

Introduction In view of the continuing depletion of natural resources, requirements for energy conservation, plant optimization and hazardous waste management, and environmental consciousness, recycling and secondary recovery of materials are being developed with increasing interest Many secondary recovery processes are being developed that apply mineral processing technology. Gravity separation, magnetic separation and flotation have all emerged as explicit methods for recovering residual values from various process streams and hazardous constituents from waste streams. Recently, a technique for concentrating metallics has been successfully reintroduced. The concept of the alternating magnetic field eddy-current separator was developed over a century ago using rudimentary electromagnets (Patent 400317 issued to Thomas Edison on March 26, 1889). Widespread acceptance was, however, hindered by high costs, marginal results and poor economic incentives for secondary recovery. With the recent increased interest in secondary recovery and the development of high-energy rare earth permanent magnets, the eddy-current separator has now gained prominent acceptance. The separation forces imparted by an eddy current separator are the function of the magnetic field intensity and the alternating frequency of the magnetic field. The evolution of permanent magnets has provided a cost effective alternative for the generation of high-intensity magnetic fields. High-energy rare earth permanent magnets have substantially reduced the capital and operating costs over the electromagnetic circuits employed in antecedent eddy-current separators. Specifically, in recent years, the strength of permanent magnets has increased several fold with neodymium-boron-iron rare earth magnets now providing an energy product of 35 million gauss-oersted. Figure 1 shows the evolution in the strength of permanent magnets. The development of these rare earth magnets has led to the design of circuits possessing a magnetic force an order of magnitude greater than that of conventional permanent magnetic circuits. The eddy-current separator has been successfully applied in several metal sorting and recovery operations. Most common is the sorting of metal from shredded automobile scrap and municipal waste. With the advent of high-frequency, high-intensity magnetic fields, the separator has advanced to the point where it has direct application in the beneficiation of fine sized metals. Relatively fine sized (-1/4 in.) metal bearing slags and spent foundry casting sands as well as precious metal hearing electronic scrap demonstrate excellent metallurgical response to the eddy-current separator, and applications have progressed to finer materials and more selective separations. Theory Electrical currents are induced in all conductors when exposed to an alternating magnetic field. The induced current generates a magnetic field in the conductor that opposes that of the alternating magnetic field. Figure 2, is a schematic illustration of generated eddy currents. In this particular example, the alternating magnetic field is produced by a series of permanent magnets mounted on the circumference of a rotor. The permanent magnets have alternating polarity. As the rotor revolves, an alternating magnetic field is produced, and the rate of revolution determines the frequency of the alternating magnetic field. When a conductor, such as a metallic disc in the illustration, is placed in the alternating magnetic field, a closed loop current flow occurs. The current loop in the conductor produces a magnetic field that is a mirror image of the alternating magnetic field. At any point in time, the induced magnetic field in the conductor directly opposes the alternating magnetic field. This opposition of magnetic fields produces an instantaneous repulsion in the conductor. The conductor is consequently repelled from the rotor. The alternating magnetic field has no effect on nonmetallic materials as they pass through the magnetic field and discharge the rotor in a natural trajectory. [ ]

Jan 1, 1992

Profiled on these pages are the eight RMCMI 1994-95 Scholarship Award Winners. Six of the eight winners were present as guests of the Institute at the June convention in Crested Butte, Colorado. Each received recognition at the Institute Awards Luncheon Monday. June 26, 1995. Each state vice president served as the host for the collegiate winner. The first and last winners - Arizona and Wyoming - were absent. Besides receiving a plaque from the Scholarship Chairman, Alan Czarnowsky, each winner receives $750 tuition credit for the coming academic year, as well as transportation, hotel lodging and meals at convention as guests of the Institute. This latter portion is paid by each state vice president. Because this is a continuing award, the winners from the previous year also receive a second $750 for tuition credit in their senior year. A resident from each of the eight RMCMI member states is selected from among Board approved institutions. Criteria for these awards to be made in the spring annually is that the recipient (1) Is a full time sophomore student who will use the tuition credit during the junior year. (2) Be both a U.S. citizen and a resident of the member state. (3) Maintain good academic standing, be pursuing a degree in a mining related field and have an expressed interest in Western coal as a possible career path. The scholarship program includes curricula other than in the mining departments, but in engineering disciplines, such as geology, mineral processing and metallurgy. Contributions to this worthy project are tax deductible to each individual RMCMI member or his firm. Through annual donations of $100 or more, the Patrons of the Institute fund the scholarship program. A listing of current donors is found elsewhere in this book. Donations to this worthwhile program are payable to RMCMI Scholarship and may be mailed to the RMCMI Office. 3000 Youngfield Street, Suite 324, Lakewood, Colorado 80215. Profiles of the 1995 Scholarship Winners follow. [ ] ARIZONA WINNER Brad Carroll University of Arizona - Tucson, Arizona Brad Carroll's hometown is Tucson, Arizona but his summer work is in Oriskany Falls, New York where he is a quality control technician, truck driver and equipment operator for the Eastern Rock Products. Brad served as vice president and treasurer for the SMWAIME student chapter at the University of Arizona for the past three years He was assistant and mine foreman at the San Xavier Mining Laboratory near Tucson. Upon graduation Brad plans to find a job in a southwest mine. He is a totally self supporting student. [ ] COLORADO WINNER Zane Znamenacek Colorado School of Mines - Golden, Colorado Zane Znamenacek hails from a small town in Colorado - Alamosa - where he 4 was a 4.3 GPA in high school. As a student at Colorado School of Mines, he has many hobbies to ease the tension of education. Foremost among these is skiing, mountain biking, billiards and spring rugby. He hopes to further mining technologies and contribute to the industry by working in it full time. In 1997 he will pursue whatever opportunities are available to graduating mining engineers

Jan 1, 1995

By Paul M. Tyler

The colony of French Guiana ( or Cayenne ) is administered by a governor , assisted by a privy council of five members . A council - general of 16 members is elected by French citizens resident in Guiana, and the colony is represented 3 in the French parliament by one deputy . The area is about 34,740 square miles . French Guiana is the largest gold producer of the French colonies , producing nearly $ 1,000,000 worth annually . Considerable prospecting has been done on the bauxite deposits , which are extensive . Copper , iron , lead , and 4 mercury deposits are also reported . In 1931 , 10,000 prospectors for gold were reported as working . The French Government is taking an active interest and has sent a committee of mining experts to explore the region ; no permits are to be issued to individual prospectors while the committee is in the colony . Plans for development of mining industry include consideration of 4,500 convicts and 2,500 natives already in the colony and available for labor .

Apr 1, 1933

By Edgardo Rabanal, Mario Adrianzén

El presente trabajo nos permitirá demostrar las bondades del potencial que tiene el enfoque de Newmont para la gestión de riesgos integral que es el Sistema de Gestión de Riesgos (RMS Risk Management Sistem) uno de los principales componentes es la Gestión de Riesgos de Fatalidad (FRM, por sus siglas en inglés de Fatal Risk Management) que es una herramienta primordial de gestión para evitar fatalidades. En los proyectos de Newmont Yanacocha (Proyecto Yanacocha Sulfuros YSP y Proyecto de Tratamiento de Aguas WTP2) se utiliza el FRM para brindar asesoramiento, acompañamiento y empoderamiento en la salud y seguridad de las empresas locales y sus colaboradores.

Sep 29, 2023

By R. K. Jonas

"Pressure leaching and pressure oxidation in autoclaves are important alternatives in the extractive processing of gold, copper and nickel ores. The application of advanced control to pressure leach and pressure oxidation autoclaves could achieve significant benefits as has been shown in alumina pressure leaching. This paper compares and contrasts alumina digestion autoclaves to other mining autoclaves with respect to advanced controls. The application of advanced control in alumina with over 30 units controlled worldwide, and its benefits will be reviewed. The design and potential benefits from advanced control for pressure oxidation and leaching will be presented.INTRODUCTIONIt is this author's position and the purpose of this paper to propose that advanced control could be effectively applied to autoclaves in the nickel, gold, and copper mining processes. This is based on the proven effectiveness of advanced control on autoclaves used in the alumina industry for pressure leaching of bauxite ores. Incremental, but significant increases in production could be realized by applying advanced control to autoclaves, as evidenced by the alumina industry, and this not being implemented in other autoclaves in the mining industry.In addition, today the mining industry is being challenged to improve their production methods. In some markets like nickel, there is pressure to improve productivity and reduce the cash cost per ton. While in other markets like copper and gold, demand is vigorous with favourable pricing, and there are advantages to increase production and productivity given limited plant capacity. Advanced control has proven its capability to improve mineral processing operations through increases in throughput, recovery, as well as reducing variability. In today's mines, autoclaves are being used to a much larger scale and with much larger importance, thus it would be beneficial to improve operational performance through the use of advanced control.Accordingly, it is the author supposition that an opportunity exists in the mining industry to use a proven advanced control technology to improve the operations and financial performance of mines using autoclaves."

Jan 1, 2012

By Larry Rayburn

Augercast piles evolved in the late forties from the process of pressure grouting open holes backfilled with stone. In 1956, a patent was issued for a cast in situ pile by pumping high pressure grout through hollow-stem, continuous flight auger as the auger is gradually withdrawn from the ground. The patent rights expired in 1973 and the use of auger-cast piles greatly expanded with most large deep foundation contractors now installing augercast piles. At one time augercast piles had a bad reputation, partly because of not having a blow count to give some engineers a confidence factor and there were some quality issues. Over the years the quality issues have been eliminated and I am sure the augercast is the most installed pile in private industry and is now being used by some State Agencies.

Jan 1, 2005

By R. K. Sinha, B. S. Choudhary, Desh Deepak, A. K. Mishra, Hemant Agrawal, Shankar Kumar

Despite several methods (empirical, statistical and machine-learning tools) to calculate blast-induced ground vibration, it is not easy to predict and simulate blast vibration precisely under varying blasting loads and strata conditions due to complications in the blasting procedure. In this study, field blast data were simulated in Ansys software using explicit dynamics, and ground vibrations for 20 single-hole blasts were monitored. The densities of emulsion explosives were in the range of 0.9 to 1.15 g/cm3. In the laboratory, rock properties were determined from rock samples collected from the mine site before blasting. The in-hole velocity of detonation (VoD) and density of the emulsion explosive were also determined and used in numerical analysis to know the ground vibrations at specific points. The results of ground vibrations predicted by the model were validated using field data.

By Drew M. Kurtz, Jeff L. Rai, Sara F. Frailey, Mohammad Ayub Iqbal

"This paper presents the foundation changes made for a five-span bridge over the Lehigh River constructed as a design-build project. During excavation within the cofferdam at Pier 2 for the construction of a spread footing to bear on rock, it proved extremely difficult to control the water entering the excavation as the sheet pile tips were variable due to the bedrock pinnacles and a weathered rock zone above the top of rock allowing water to pass below the sheeting. Water also entered from the bottom of the excavation, possibly due to the presence of solution openings within the dolomite bedrock. After repeated failures to achieve subgrade elevation and maintain a dry excavation, a design change to drilled shafts was made. Additional borings were performed for each of the shaft locations to explore the area underlain by karstic dolomite rock. A seal consisting of tremie concrete with adequate weight was placed to counter the differential head of water and the three drilled shafts (with minimum 25 feet [7.62 meter] rock sockets) were installed. A detailed construction sequence was followed and advanced quality control testing was performed. The construction of Pier 2 was completed successfully.1. INTRODUCTIONThis paper presents the description of the design change made from spread footing to drilled shafts as a result of site conditions encountered during the excavation for the spread footing for a bridge pier in the Lehigh River in Allentown, Pennsylvania. The bridge is located in an area underlain with dolomite rock, presenting karstic conditions including irregular top of rock and solution openings that provided high hydraulic conductivity below the top of rock. Also, the presence of a zone of weathered rock and pinnacle rock prevented the advancement of sheet piles when constructing the cofferdam. Thus, the difficulties of advancing the excavation to the desired spread footing level resulted in the design change to drilled shafts during construction. Since the project was Design-Build, the design could be changed by a collaborative process through the efforts of the Contractor, its geotechnical and structural engineers, and the State's (owner's) geotechnical and structural engineers and construction management staff."

Jan 1, 2016

By R. F. Mehl, C. S. Barrett, A. G. Guy

INTRODUCTION IN the last few years this laboratory has published a series of papers on the mecha¬nism of age -hardening.14,1,6,11,20 Briefly stated it has been proposed that hardening is caused by lattice strains created by lat¬tice coherency between matrix and precipi¬tate; much experimental evidence has been advanced to support this thesis. The system Cu-Be is an attractive one to study. It is a system that exhibits marked age hardening; it ought to be subject to the type of analysis of structural changes hitherto explored and it is a prominent example of "discontinuous precipitation," which, though studied in other cases, 6,20 remains largely unexplained. This research shows that hardening in the Cu-Be system proceeds essentially as proposed earlier.14 Guinier-Preston zones have been observed to form on the {100) planes of the matrix; no transition lattice was found. Aging and overaging were ob¬served to occur most rapidly in the region of discontinuous precipitation-the grain boundary-apparently accelerated there by strain. The Constitution of the Cu-Be System The Cu-Be constitution diagram is shown in Fig I. The structure of the ? phase was determined by Misch16 as of the caesium-chloride type with a lattice con¬stant of 2.598 Å High temperature X ray photograms of 7.2 pct Be alloy made by Kossolapow and Trapesnikow13 led them to conclude that the structure of the P phase is simply disordered body-centered cubic with [ao] = 2.79 Å at 750°C. Previous Work The initial work on the age-hardening of Cu-Be alloys was that of Masing, Dahl, Holm, and Haase. Their numerous papers were published in book form in 1929, sub¬sequently translated.18 The effects of Be content, solution temperature, aging tem¬perature, and cold work on the hardness developed in these alloys were studied. An initial decrease in the electrical conduc¬tivity was observed when strips of a 2.5 pct Be alloy were aged at temperatures from 200 to 350°C; a wire of the same analysis failed to exhibit this decrease when aged at 350°C. A volume decrease of 0.6 pct oc¬curred during aging at 250°C. Microscopic investigations of quenched and aged alloys disclosed a regularly ori¬ented "striping" (ripples) on the a and on the ß grains. In the case of the ß the cause of the striping was held to be decomposition

Jan 1, 1948

By Tom Treleaven

This guide presents numerous patterns that provide 8 millisecond separations between initiated charges. The guide is tabulated in seven sections to provide quick reference by number of decks or bunch blasting. The pattern is presented in the section where the highest number of decks works. It should be noted that patterns applicable to multiple deck shootings are also applicable for fewer decks.

Jan 1, 1997

By James M. Barker

Sulfur is a nonmetallic element of great physical and economic importance to the world. It is widely but sparingly distributed throughout the hydrosphere, lithosphere, and biosphere. Sulfur is the tenth most abundant element in the universe and eighth most abundant in the sun. In the earth's crust, which is mainly igneous, it ranks 14th, but is eighth or ninth in sediments (Kaplan, 1972; Stanton, 1972). It apparently is very abundant in the core of the earth, because it is a strong chalcophile, and it is fifth in abundance in stony and iron meteorites (Field, 1972) where it occurs as trolite (FeS). In ancient times sulfur was called brimstone, literally "burning stone." Today the term brimstone is used interchangeably with the term elemental sulfur. Shelton (1979) summarized most of the common definitions of terms, grades, and specifications for the sulfur industry as follows (with minor additions): Sources of Sulfur: Combined sulfur-Sulfur that occurs in nature combined with other elements. Cupriferous pyrites-Pyrite containing relatively minor amounts of copper sulfide minerals. Hydrogen sulfide-A toxic gas (H2S) occurring in natural gas and petroleum. Involuntary sulfur-Sulfur produced primarily as a result of legislative or process mandates. Native sulfur-Sulfur that occurs in nature in the elemental (uncombined) form. Nonferrous metal sulfides-Copper, lead, zinc, nickel, and molybdenum sulfides that are processed for their metal content. Organic sulfurs-Complex organic sulfur compounds occurring in petroleum, coal, oil shale, and tar sands. Pyrites-Iron sulfide minerals that include pyrite, marcasite, and pyrrhotite. Sulfate sulfurs-Sulfur in anhydrite and gypsum. Voluntary sulfur-Sulfur produced in response to market forces. Basic Sulfur Products Produced and Marketed: Acid sludge-Contaminated sulfuric acid usually returned to acid plants for reconstitution. Brimstone-Synonymous with crude sulfur. Bright sulfur-Crude sulfur free of discoloring impurities and bright yellow in color. Broken sulfur-Solid crude sulfur crushed to -8 in. Byproduct sulfuric acid--Sulfuric acid produced as a byproduct of a metallurgical or industrial process, generally relating to combined sulfur sources. Crude sulfur-Commercial nomenclature for elemental sulfur. Dark sulfur-Crude sulfur discolored by minor quantities of hydrocarbons ranging up to 0.3 % carbon content. Elemental sulfur-Processed sulfur in the elemental form produced from native sulfur or combined sulfur sources, generally with a minimum sulfur content of 99.5%. Formed sulfur-Elemental sulfur cast or pressed into particular shapes to enhance handling and to suppress dust generation and moisture retention. Frasch sulfur-Elemental sulfur produced from native sulfur sources by the Frasch mining process. Hydrogen sulfide-Associated with natural gas or petroleum and produced at refineries and coke oven plants; used to make sulfuric acid or recovered sulfur. Liquid sulfur-Synonymous with molten sulfur. Liquid sulfur dioxide-Purified sulfur dioxide compressed to the liquid phase. Molten sulfur-Crude sulfur in the molten phase.

Jan 1, 1983

I The South Platform of the Gippsland Basin is an extensive area of shallow basement covered by a relatively-thin Late Mesozoic-Cainozoic section. Although the sporadic exploration to-date has not resulted in any hydrocarbon discoveries, the area is under-explored and its taste potential has not yet been fully evaluated. The best potential appears to be in areas underlain by the Golden Beach Megasequence where structures are mainly related to basement fault blocks.

Jan 1, 1992

By Shangshu Li, Xin Li, Xionggang Lu, Xingli Zou, Kai Zheng, Yinshuai Wang

Ti5Si3/TiC composite has been successfully prepared from the titanium-rich slag/SiO2/C mixtures precursors by an electrochemical process. The electrochemical production process was carried out in molten CaCl2 salt at 1000 °C and 3.8 V. A pressed cylindrical pellet of titanium-rich slag/SiO2/C mixtures served as a cathode, and a solid oxide oxygen-ion-conducting membrane (SOM) tube filled with carbon-saturated liquid tin acted as an anode. The phase transformation of the cathode pellets during electrolysis process was investigated, the microstructure of the obtained products was characterized. It is found that the reaction pathways can be divided into three main stages during the electro-reduction process. The first stage is the generation of calcium compound, the second stage is the electrochemical reduction of the compound, and the third stage is the formation of Ti5Si3/TiC composite. The prepared Ti5Si3/TiC composite exhibits homogenous and nodular particle morphology.

Mar 1, 2018

By F. J. Alcock

THE Magdalen islands have recently been attracting attention as a possible source of manganese. As early as 1880 small masses of manganese oxides were known to occur in the soil and at least one attempt was made to develop them. In 1939, after the outbreak of war, interest in the possibilities of the field was again aroused and during the winter of 1939-40 claims were taken up by two groups of Toronto interests. The islands also contain large quantities of gypsum. During the summer of 1940, the writer mapped the islands geologically, giving particular attention to a study of the manganese occurrences. For a base-map, the chart of the islands was enlarged to a scale of half a mile to an inch. Additional roads were added from traverses carried out in connection with the geological work, and form lines with approximate 100-foot intervals were put on from barometer readings. The geological map is the first that has been prepared of the islands. Previous Work In the summer of 1880, James Richardson of the Geological Survey of Canada studied the rocks of the islands and his r~port concerning them appears as Part G of the Report of Progress, 1879-80. In 1903, J. Obalski, Inspector of Mines for the Department of Lands, Mines and Fisheries of the Province of Quebec, visited the islands, chiefly to investigate the occurrences of manganese and gypsum, and his notes are found in the report on mining operations in the Province for that year. Around 1890, Robert Chalmers of the Geological Survey paid a visit to the islands, and his observations, which chiefly concerned the surface geology, appear in the Annual Report of the Survey, Vol. VII, 1894, Part M, p. 94. The next geological work was carried out by John M. Clarke, Director of the New York State Geological Survey. Clarke paid many visits to Gaspé peninsula between the years 1900 and 1920, collecting fossils and gathering h1s~orical data, and extended his investigations of Gaspé county over to the Magdalens. His Observations on the Magda/en Islands is included in the New York State Museum Bulletin 149, seventh report of the Director, 1910.

Jan 1, 1941

By Timothy O’Rourke, Karrie Buxton, Chris Lynagh, Daniel Dobbels, Frederick Vincent

The Doan Valley Storage Tunnel Project in Cleveland Ohio was constructed to control Combined Sewer Overflows (CSOs). It is a complex system of three tunnels ranging from 8.5 to 18 feet in diameter with a total length of about 2.3 miles that was put into operation in mid-2021. The project lies within and below the cultural, educational, and medical hub of Cleveland, which presented unique design and construction challenges. This paper provides a case history of the design and construction, with particular attention given to lessons learned in devising a large tunnel system that can carry both dry and wet weather flows constructed in rock with limited cover, within a flood plain area and vibrant urban center

Dec 1, 2022

By Xuanxue Mo, Kaihui Yang

"Abstract- The Laochang mine, located in the Sanjiang area of southwestern Yunnan Province of China, is a volcanogenic massive Pb-Zn-Cu sulfide deposit. It is hosted by a pyroclastic sequence of Barly Carboniferous age, namely the lower member of the Yiliu Group, which was intruded by syenite and rhyolite porphyry . The volcanic suite is basaltic or basaltic-andesitic in composition, has alkaline affinities, and is associated with the initial rifting along the margin of the Baoshan-Shanstate continental rnicroplate (Yang, 1989). The ores are typically Pb>Zn>Cu in composition, averaging 3.820Jo Pb, 3.51% Zn, from 0.01% to 1.85% Cu (0.107% av.), a high average content of Ag (113 g/t) and recoverable amounts of Au, Tl, Gd, Ga, Ge, In. A massive sulflde zone, in which lenticular and stratiform orebodies are localized in a sulflde-carbonate-silica shale unit or sulfldic tufflte horizon that usually overlies coarse-grained pyroclastic rocks, is underlain by a stringer sulflde zone developed in a subvolcanic intrusion or volcanic sequence. The sulfide mineral assemblages, from the top to the bottom of the deposit, are: realgar + orpiment - galena + sphalerite + pyrite- chalcopyrite + pyrite + pyrrhotite + arsenopyrite. Oxide and sulfate minerais occur rarely in the massive ores. The massive ores are generally fine-grained and banded, but coarse-grained ore, colloform and framboidal texture, and growth-zoned pyrite and sphalerite are common. Sedimentary features such as graded bedding, brecciated and deformed ore clasts, and chaotically emplaced blocks, are well preserved, indicating that the massive orebodies have undergone slumping and dis­ placement. Alteration is weak in the hanging-wall rocks, but strong in the stringer zone. Two dis­ tinctive alteration zones have been identified: the upper zone, characterized by an assemblage of quartz, carbonates, chlorite, albite, zeolite and sericite, and the lower zone containing diopside, trema­ lite, actinolite, gamet, clinozoisite, and epidote.The general features of the Laochang deposit are in accord with the descriptive mode! of VMS deposits (Lydon, 1984). However, it falls into neither the Zn-Cu group nor the Zn-Pb-Cu group chemically (Franklin et al., 1981). The depositional setting of the Laochang deposit is quite different from Cyprus or Besshi-type massive sulfide deposits. Laochang is hosted by alkaline lavas that were erupted in a submarine continental rift. Although some features of the Laochang deposit are similar to those of Kuroko-type deposits, there are remarkable differences in the alteration mineral assemblage, the proportion of ore-forming elements (lead enriched) and the amounts of oxides and sulfates. These suggest corresponding differences in ore fluid composition and the associated ore-forming environment. Thus, the authors suggest that the Laochang deposit may be a distinct type of VMS deposit."

Jan 1, 1993

By Ygor Pereira de Lima, Iana Costa Carvalho, Marcelo Henrique Prado da Silva, Talita Gama de Sousa, Andrey Mariano dos Santos, Paulo Davi Borges Esteves, Rodolfo da Silva Teixeira, Andersan dos Santos Paula

Durante muitos anos, as ligas convencionais foram base para o desenvolvimento de novos materiais metálicos, com propriedades melhores que as até então conhecidas. No entanto, na última década, as Ligas de Alta Entropia (LAE) trazem uma nova abordagem para a produção de materiais avançados, com excelentes propriedades e potencial para diversas aplicações. Em particular, as ligas do sistema Al-Co-Cr-Fe-Ni também se destacam por promoverem uma classe de LAE de baixa densidade e têm sido foco de inúmeros estudos no meio acadêmico atual. O presente artigo traz um estudo de otimização da preparação metalográfica da liga AlCo2Cr2FeNi2, a partir de 3 rotas diferentes de polimento e suas análises via microscopia eletrônica de varredura (MEV) e difração de Raios X (DRX). Além disso, foram avaliadas as modificações estruturais da liga em função de um tratamento térmico de solubilização (1050 ºC por 1 hora seguido de resfriamento em água). Os resultados das análises demonstraram a rota de polimento eletrolítico promissora para a caracterização da LAE em questão e a análise conjunta dos resultados de DRX e MEV, somado ao confronto com a literatura, permitiram identificar as fases presentes e suas modificações microestruturais em função do tratamento térmico.

Oct 24, 2019

By Ludmila Vieira da Silva Matos

O presente artigo investigou como a condição de operação das zonas de resfriamento em máquina de lingotamento de placas contribui para o desempenho de lanças air mist. Tal investigação foi realizada no laboratório da Spraying Systems Brasil a partir das premissas de projeto de uma nova máquina de lingotamento e um novo conceito de lança air mist: menor consumo de ar comprimido, amplo turndown e qualidade de cobertura por toda a curva de operação do resfriamento. As curvas de performance foram montadas para diferentes condições de utilização de ar comprimido: de 1,5 a 4,5bar de pressão constante. Cada lança teve das vazões mínimas às máximas de água ensaiadas. A qualidade do perfil do jato produzido foi verificada para cada ponto das curvas obtidas, em mesa de distribuição no laboratório da Spraying Systems. Com as imagens em mãos, foi possível selecionar aquelas condições de vazão de água e pressão de ar comprimido com melhores perfis de jato e cobertura. Como resultado, a fabricante da máquina pode validar e/ou modificar a curva de trabalho de resfriamento da máquina e garantir as melhores condições do perfil do jato e uniformidade de resfriamento.

Oct 1, 2019

By N. Valkanov

This paper presents results of an investigation into the connection between minerals liberation management and flotation, responding to lead-zinc concentrator ?Erma reka?, in Bulgaria. Monitoring of a Zn flotation circuit was carried out. The causes for the high silica content in the final Zn concentrate were established. Quartz is present mainly as liberated particles (> 60?80 %) in the fine fractions of the products; therefore the selectivity of the flotation process is not effective. Two approaches were tested to reduce the quartz content of Zn concentrate: froth washing in Zn cleaner flotation and new gangue depressants in the Zn circuit. Experimental results from bench-scale flotation and industrial tests show that it is possibile to reduce the silica content of final Zn concentrate more than 2 times without the need for extensive regrinding. The depression of liberated quartz particles on all operations of Zn circuit using stage depressant addition is the right solution to produce high-grade Zn concentrate that meets the metallurgical requirements.

Aug 1, 2013

A Directory of Computer Programs Applicable to US Mining Practices and Problems. A. L. Sanford, T. L. Myers, and J. F. Stiehr. USBM OFR 131-78, Nov. 1977. A Master Environmental Control and Mine System Design Simulator for Underground Coal Mining. Tape MDS-5. Pennsylvania State University. USBM CT 1.77, Dec. 1975. Contains computer programs on a dynamic general purpose computer simulation model for underground coal mining. A Method for Computing Stabilization Pressures for Excavations in Incompetent Rock. J. D. Dixon and M. A. Mahtab. USBM RI 8128, 1976. Describes technique for determining the confining pressures that must be provided for stabilizing underground openings in incompetent rock. Accident Cost Indicator Model to Estimate Costs to Industry and Society From Work-Related Injuries and Deaths in Underground Coal Mining. Vol. I.III. D. G. DiCanio, A. H. Nakata, D. Colvert, and E. G. LaVeque. OFR 39(1)(3)-77, Dec. 1976. Describes a computer-based model for estimating the tangible costs of injuries and deaths from work-related accidents In underground coal mines. An Interactive Computer System for Evaluating Coal Mine Illumination. R. Goldstein. USBM OFR 110-80, March 1980. Computer system for calculating the illumination on coal mine surfaces due to machine-mounted lights. Analytical Modeling of Mine Roof Behavior Using Statistical Material Properties. R. T. Langland and F. J. Tokarz. USBM UCRL-51876, Aug. 1975. Analytical study of coal mine roof behavior using a computer model of a room-and-pillar mining method. Application of a Total System Surface Mine Simulator to Coal Stripping. Vol. I-VII. Pennsylvania State University. USBM OFR 33(1)(7)-78, Aug. 1978. Describes model development, input and output documentation, three case studies of an open-pit materials handling simulator, and development of two equipment selection models and a cost model. Characterization of the Structural Behavior of Rock Masses. Vol. I-II. L. R. Herrmann and M. A. Taylor. USBM OFR 67(1X2)-75, Sept. 1974. Computer subroutines for characterization of rock behavior, Including variability of properties within the rock mass, planes of weakness orthotropy, strength criteria, and post-failure behavior. Coal Mine Electrical System Evaluation. Vol. I-VII, L. A. Morley, et al. USBM OFF! 61(1)(7)-78, 1977. A concept to improve underground coal mine electrical system safety and availability. This proposed technique is based upon the ability to predict incipient failures in the mine power system. Prediction is made possible by a new method which uses a minicomputer to implement pattern recognition algorithms. Computer Modeling of Fluid Flow During Production and Environmental Restoration Phases of In Situ Uranium Leaching. R. D. Schmidt. USBM RI 8479, 1980. Describes development and application of a computer model for simulating the hydrological activity associated with in situ leaching. Interpretation of Rock Mechanics Data, Vol. II (A Guide to Using UTAH2). W. G. Pariseau. USBM OFR 47(2)-80, June 1978. Brief description of a two-dimensional elastic-plastic finite element program intended for mine stability analysis. Iterative Approximation Techniques for Microseismic Source Location. G. H. Dechman and Meng-Cherng Sun. USBM RI 8254, 1977. Iterative approximation method for microseismic source location developed to adapt microseismic techniques for rock structure analysis to investigations of surface problems such as slope failure in an open-pit mine. Limits and Cost Sensitivity of Alternative Parting Handling Methods. Vol. I-II. T. E. Finch, D. R. Haley, and C. J. Speaks, Jr. USBM OFF! 117(1)(2)-77, March 1977. Programs to examine alternative methods of handling the parting between two coal seams in a surface mining operation. Alternative methods consist of equipment implementation in either a stowing or haulback technique. Methane-Water Flow in Coalbeds. H. S. Price. USBM CT 1-79, April 1972. This computer program calculates transient, two-dimensional, gas¬water flow in a porous medium. Plastic Canopy-A Computer Program for the Structural Analysis of Protective Canopies. K. D. Winters, G. A. Gavan, and J. C. Ault. USBM IC 8795, 1979. Presents a FORTRAN IV program for the structural analysis of protective canopies used In underground mines and rollover protective structures used in surface mines. The Three-Dimensional Structural Analysis of Double-Entry and Single-Entry Coal Mines. Vol. I-III. Agbabia Associates. USBM OFF 16(1)(3)-80, Oct. 1978. Describes the computer program designed to perform a three-dimensional finite element analysis of an instrumented section of double- and single-entry coal mines. Underground Mine Evacuation Plans Analyzed by Computers. D. Tesarik, D. Nicholson, and A. B. Boghani. MSHA, Vol. 4, No. 5, Oct. 1979. USBM has developed a computer program to evaluate and construct mine evacuation procedures and plans.

Jan 11, 1981