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By J. Paraszczak

Metal mining at great depths presents a number of serious challenges for mine operators. Among them is the high demand for fresh air required to cool down mine openings, evacuate noxious gases and contaminants and provide sufficient amounts of oxygen for miners. At the same time, modern mechanized mines extensively use diesel-powered load-haul-dump (LHD) machines, trucks and other mobile equipment. These vehicles not only emit exhaust gases and diesel particulate matter (DPM), but constitute an additional source of heat. As mine regulations get steadily more stringent with regard to air quality, the use of diesel engines has an additional adverse impact on ventilation costs. In this context, the present paper examines possible alternatives for diesel power trains, both those commercially available and those in development. They are reviewed with regard to their principles, required infrastructure, stage of technology development and progress. The questions of their flexibility, practicality and economic viability are also addressed. Finally, their possible benefits and potential for implementation in the conditions of deep metal mines are discussed. The paper concludes with short- to medium-term predictions concerning promising drive alternatives for vehicles destined to operate in deep metal mines.

Jan 1, 2009

By J. Hamisch

Climate policy regarding perfluorocarbons (PFCs) may have a significant influence on investment decisions in the production of primary aluminum. This work demonstrates an integrated analysis of the effectiveness and likely economic consequences of different climate policy options. In our study we first compare atmospheric observations to the available estimates of PFC emissions for the baseline years 1990 and 1995. We then present projections for regional emissions of PFCs from the aluminum industry using the MIT Emissions Projection and Policy Analysis model under different policy scenarios. Abatement costs for emissions of PFCs and C02 are compared in the context of the Kyoto Protocol.

Jan 1, 1999

By Henry Wurtz

HERACLITUS, a sage of antiquity, called the dark philosopher, who refused a throne, preferring a hermit's cell, propounded, twenty-four centuries since, the maxim : [ ] War (or strife) engenders all things. This, though probably intended by Heraclitus to apply especially to the internal forces of nature, is often said, with equal reason, of the affairs of men. Controversial strife, whether fortunately or unfortunately, is a crucible through which all new discoveries in science, and all technical applications of science must pass-a test which they must all endure before they can become so vitalized as to germinate, so to speak, take root in the human mind, grow tip, and overspread the earth. The greater the number and the power of the elements arrayed against such a growth, and of the influences hostile thereto, the greater should be the inherent vitality of the germ, the more strenuous, skilful, and persistent its cultivators and upholders. During the decade last past we have had, in spite of the severe stringency of the times, an active growth of this kind in progress, whose prospective importance it would now be difficult to overrate. This is the movement which has for its motive the idea that, generally speaking, fuel should be gaseous in form, and which has for its goal the introduction into general public use of gaseous products, made by cheap and rapid processes and on a gigantic scale, distributed throughout our cities and towns in distribution-systems which shall be proportionately gigantic, and sold at prices which will bring such fuel within the means of the poorest householders. Personally, for ten years past, the writer has never failed, on occasions public or private, to urge his belief that the realization of this idea, deemed by him a certainty of the future, will bring about

Jan 1, 1880

By Izabela Silva Bicalho

A utilização de fluidos de corte no processo de retificação tem como principais objetivos lubrificar e refrigerar a zona de corte, limpar a superfície do rebolo e minimizar a corrosão. Observa-se que a maioria dos óleos de corte aplicados na zona de retificação apresentam vantagens quanto às propriedades lubrificantes e corrosivas, porém perdem seu poder de refrigeração, quando comparados aos fluidos emulsionáveis. O presente estudo tem como objetivo avaliar o ganho da propriedade refrigerante dos óleos vegetais com e sem aditivos, e compará-la com a dos fluidos de corte integral. Para isso foi realizada análise da curva de resfriamento, termogravimetria (TG), ponto de fulgor e teste de corrosão em amostras com e sem aditivos de óleo vegetais (soja e milho) e de um fluido de corte mineral parafínico. As curvas de resfriamento foram obtidas conforme a ASTM D6200 e as curvas TG foram determinadas em uma termobalança. O ponto de fulgor foi determinado conforme a ASTM D92-25. O teste de corrosão foi realizado conforme a NBR 10505. O ponto de fulgor e a termogravimetria indicaram uma maior estabilidade ao aumento da temperatura dos óleos vegetais em relação ao mineral. Os óleos vegetais analisados apresentaram melhor capacidade de resfriamento quando comparados com o fluido de corte mineral sendo sua ordem apresentada da seguinte maneira: milho > soja > mineral. A amostra aditivada de óleo de soja também promoveu aumento da capacidade de resfriamento e diminuição da estabilidade térmica.

Aug 7, 2018

By Gabriel Gonçalves Pessoa de Castro

O trabalho teve por objetivo produzir uma liga Al AA1070 com microestrutura ultrafina via prensagem por canais equiangulares. O processo empregou a rota C com 2 passes consecutivos a frio e acumulou uma deformação ?2 = 2,38. O material de partida é proveniente de um processo de laminação a quente na qual a microestrutura resultante era composta de grãos grosseiros com tamanho de grão de 14,5 ± 19,1 ?m e dureza de 31,1 ± 1,9 Vickers. Foi realizada a caracterização microestrutural com o auxílio das técnicas de microscopia eletrônica de varredura (MEV) e de difração de elétrons retroespalhados. O comportamento mecânico das amostras foi avaliado por ensaios de dureza Vickers, a fim de se determinar a energia armazenada durante os passes. Os resultados obtidos mostraram que o material de partida apresentou estrutura parcialmente recristalizada, decorrente do processo termomecânico de laminação. A deformação cisalhante severa que ocorre na interseção entre os canais durante o processamento via ECAP permitiu um intenso refinamento de grãos. O tamanho de grão após o 2° passe foi da ordem de 1,6 ± 1,7 µm. A dureza após o 1° passe quase dobrou em relação ao material de partida, mas praticamente se manteve no passe seguinte, sugerindo uma possível estabilidade. Pode-se concluir que ocorreu um considerável refinamento do tamanho de grão em função da elevada fragmentação e rotação da subestrutura após os passes de deformação.

Aug 8, 2018

By Raimison Bezerra de Assis

Ferritas de níquel-zinco são materiais cerâmicos ferrimagnéticos com estrutura cristalina cúbica do tipo espinélio, pertencente ao grupo espacial Fd3m, sendo uma solução sólida de composição NiO, ZnO e Fe2O3. O método de polimerização de complexos tem enorme potencial para obtenção de cerâmicas magnéticas, por se tratar de um processo simples, que se origina a partir de materiais com elevado grau de pureza, o que leva à obtenção de pós com elevada homogeneidade química e elevada área superficial. Este trabalho tem como objetivo avaliar as características estruturais e morfológicas das ferritas Ni0,25Zn0,75Fe2O4 e NiFe2O4 obtidas através do método polimerização de complexos. A solução foi submetida a uma temperatura final de 120°C até a formação da resina, pirolisada a uma temperatura de 350°C durante 2 horas e calcinada a 500°C durante 2 horas. Os pós resultantes foram caracterizados por difração de raios X (DRX), análises térmicas (TG/ DSC) e microscopia eletrônica de varredura (MEV). Os resultados do DRX das duas composições apresentaram formação de fase majoritária ferrita. Os resultados das micrografias obtidas por MEV mostraram a formação de partículas aglomeradas com placas longitudinais para ambas composições, sendo características microestruturais importantes para aplicação magnética. O método de polimerização de complexos se apresentou como um método promissor para obtenção de pós cerâmicos de ferrita de níquel e níquel-zinco para aplicação magnética.

Aug 8, 2018

By R. L. Bullock

For the past 30 years there has been a gradual evolution of mechanical excavating systems in underground hard rock mining applications. This paper traces many of the tests of various tools and methods to break hard rock, up to the present. The tools include impact hammers, boring machines, disc on boom mining machines, disc on revolving wheels and drums, picks and drag bits on revolving hubs, rock splitters, slot cutting systems, and with customized explosives/powder mini-blasting. While the progress has been slow, successes are being achieved in hard rock and more opportunities exist today than ever before.

Jan 1, 1995

By Richard D. Miller

This publication contains routine analyses and related source data for 350 natural gas samples from 19 States collected during calendar year 1362 as part of a continuous survey of the United States for occurrences of helium in natural gas. This survey has been conducted by the Helium Activity of the Bureau of Mines since 1917. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus. Four previous publications have been made to present the results of 5,648 gas analyses made by the Bureau of Mines, Helium Activity, prior to 1962. The first, Bulletin 486, 3/ contains analyses and data on 2,195 gas samples collected during the period 1917-47. Bulletin 576, 4/ the second publication, includes data and analyses for 1,575 samples collected from 1947 through May 1956. The third bulletin contains 1,444 analyses and source data of samples obtained from May 1956 to January 1, 1961.

Jan 1, 1964

By Richard D. Miller

This publication contains routine analyses and related source data for 350 natural gas samples from 19 States collected during calendar year 1962 as part of a continuous survey of the United States for occurrences of helium in natural gas. This survey has been conducted by the Helium Activity of the Bureau of Mines since 1917. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus. Four previous publications have been made to present the results of 5,648 gas analyses made by the Bureau of Mines, Helium Activity, prior to 1962. The first, Bulletin 486, 3/ contains analyses and data on 2,195 gas samples collected during the period 1917-47. Bulletin 576, 4/ the second publication, includes data and analyses for 1,575 samples collected from 1947 through May 1956. The third bulletin 5/ contains 1,444 analyses and source data of samples obtained from May 1956 to January 1, 1961.

Jan 1, 1964

By W. L. Dare

The Federal Bureau of Mines is publishing a series of studies on the methods and costs of mining uranium on the Colorado Plateau. This report describes the longwall-mining methods and techniques used at the Radon mine, Big Indian district, San Juan County, Utah. The tabular Radon ore body lies on the southwest flank of the Lisbon Valley anticline, strikes N. 10° W., dips 7° SW., and has an average thickness of 4-1/2 to 5 ft. The mine is developed by a three-compartment vertical shaft, a haulage level driven beneath the ore, and a system of drifts driven within and parallel to the strike of the ore.

Jan 1, 1961

By A. W. Fahrenwald

The purpose of screening is to separate a crushed or natural product into one or more products in which size of grain is constant, or within certain size limits. The ore dresser finds need for this operation in the laboratory, in the study of ore-dressing processes, and for various purposes in the plants. In the plant, for example, screens are employed in closed circuit with crushing devices such as rolls, and sometimes are used in closed circuit with ball mills. Screens are generally used to prepare jig feed where a sized feed is wanted. For any given sieve opening there is in any feed a certain percentage of grains that will pass through the sieve meshes only with difficulty and under favorable conditions. For example, cylindrical grains of length greater than the maximum dimension of the sieve mesh and of diameter less than the sieve opening pass the sieve only when the long axis of the grain is normal or nearly normal to the sieve. Whether such grains should actually be in the through's or the oversize of a screening operation--considered from the point of view of the subsequent treatment of the grains--can not be said. The grains that pass the sieve opening in a screening process only under-favorable conditions have been named "difficult" grains by R. K. Warner.4 In many ore-dressing flow-sheets it probably matters little whether these difficult grains show up in the screen through's or oversize. The main objection to them is that they are sieve-blinding.

Jan 1, 1929

By Richard B. Berg

Chlorite veins in the Silver Star district (40 km southeast of Butte) were of little interest to those who were mining gold and silver in the late 19th century. It wasn't until 1975 that unusually pure magnesian chlorite of the variety clinochlore was identified from a ?talc? claim in this district. In 1977 tests by Cyprus Industrial Minerals showed that this chlorite was suitable for use in ceramics. Mining begun in that year continues. These replacement veins of chlorite in Precambrian quartzofeldspathic gneiss differ from the metalliferous veins to the northwest in both attitude and mineralogy.

Jan 1, 1982

By Earle E. Schumacher, Alexander G. Souden

IN the field of physical metallurgy it is becoming increasingly difficult to keep abreast of the recent develop¬ments since the diversity of investigations is so great and the literature so voluminous. The purpose of this review is to present the more important advances in the nonferrous field during the past few years, the topics discussed being classified broadly as fundamental and practical. The former includes those studies that have done most toward developing the basic science of metals and alloys, and the latter includes technical developments and applications. With the rapid growth of the metal

Jan 1, 1938

By I. du Plessis

The metallurgical response of a difficult to treat coal and an easy to treat coal orebody were investigated in terms of the coal yield and the coal quality in a basic coal recovery flowsheet. The purpose of this paper is to show trends and derive principles for the treatment of different coal types. This investigation entailed using the LIMN simulator to simulate the metallurgical response by varying the plant operational parameters. The controllable plant variables investigated were: ?Cyclone size ?Screen and hydro-cyclone cut points ?Medium cut density ?Feed particle size distribution.

Jan 1, 2010

By R. S. Fowkes

The Bureau of Mines constructed a fully automated pilot plant facility to study the hydraulic transportation of solids through a lock hopper feeder system. An equation for the energy requirements to transport coarse solids hydraulically proved applicable to this system. Optimum velocities were obtained for limestone, mine refuse, and bituminous coal. The experimental data, calculations, and graphs show the effect of velocity, specific gravity, and solids concentration on head loss and power requirements. Other data were obtained and evaluated to determine the effect of particle size on head loss. Results also are given for (a) tests using friction reducing polymers; (b) tests using seven test sections of steel alloy pipe to determine their wear characteristics; (c) tests to determine spatial segregation of moving particles; and (d) tests to determine the effect of shape, size, and specific gravity on particle velocity in a horizontal pipeline. The lock hopper feeder system was found practical for continuous hydraulic transportation of the material types and size ranges tested.

Jan 1, 1969

By C. B. Kettering

In the early operations of the Inspiration Consolidated Copper Company, which extended from 1914 to 1926, the ore as mined contained principally sulphide copper minerals, manly chalcocite (Cu2S), This ore was milled in a 20,000-ton concentrator and the copper was recovered as a flotation concentrate which, was smelted at the nearby plant of the I ternational Smelting and Refining Company. In those days no attempt was made torecovercopper from any oxide minerals present. As mining operations progressed it soon became evident that the proportion of oxide minerals present would steadily increase, and. it was realized that some method of treatment would have to be developed whereby copper could' be recovered from both oxide and. sulphide minerals contained in the ore. A research program was instituted and after some years of experimental and, pilot plant work a new hydro-metallurgical process was developed whereby it became possible to extract copper from both the oxide and. sulphide minerals in a single leaching operation. The solvent adopted consisted of a mixture of sulphuric acid and ferric sulphate,' Following dissolution, the dissolved copper would be recovered by electrolysis. Also in the process of electrolyzing, spent solutions of sulphuric acid, H2SO4, and. ferric sulphate, Fe2(SOk)3, would be regeneratede and. somade available for continuous reuse. The process appeared to be a success and the decision was made to build a full-sized leaching plant for the future treatment of I spiration mixed ore. Construction was started and the leaching plant was completed in 1926, With the start of ferric-sulphate leaching the Inspiration Concentrator was shut down and, with the exception of a few short time runs has not operated since that time. The ferric sulphate leaching process served. Inspiration well for some 30 years and during that time won a name for itself as a classic example of hydro-metallurgical treatment of mixed sulphide oxide ores. Originally the plant was designed. to process some 7,500 tons per day of a mixed ore containing about 1,2% copper, of which 60% was present as oxide and. 40% as sulphide, Down through the years various improvements were made for the purpose of increasing plant capacity and as well to change the limiting 'factor of sulphide-oxide ratio, The final result was a leaching capacity of 9,600 tons per day when treating a 1% copper ore with a reversal of the sulphide-oxide ratio to 60% sulphide and 40% oxide.

Jan 1, 1958

H. DEAN JACOT RMCMI PRESIDENT 1987-1988 on behalf of The RMCMI Board of Directors and Officers The Rocky Mountain Coal Mining Institute cordially invites you and your family to attend the 84th Regular Meeting and Convention to be held June 26, 27 and 28, 1988 at Beaver Run Resort Breckenridge, Colorado

Jan 1, 1987

By Herman Wotruba

Mercury emissions and other environmental impacts in small-scale gold mining are a world-wide problem. "Clean" or better: "Cleaner" technologies have -apart from being environmentally sound -to guarantee a higher income and better working conditions for the miners in order to have a chance for long-term acceptance. In small scale primary gold mining in several South American countries, a number of techniques have been adapted and improved so that they not only were accepted due to their efficiency and easy handling, but they could also significantly lower mercury emissions.

Jan 1, 2003

By Peter Yen

This session consists of five papers. Three involved research on the properties of grout materials, specifically ultrafine cements and polyurethane grouts. Two papers present the development of soil grouting technology and monitoring methods. Of great interest are the papers on ultrafine grout penetrability testing focusing on the pressure filtration effects encountered in permeation grouting applications (Ericksson, Stille and Mittag, Savidis). The comparison testing of hydrophilic and hydrophobic polyurethane grouts submitted by Vrignaud, Ballivy, Perret and Fernagu assessed the long-term performance of these materials for repairing saturated cracks in concrete, subject to thermal expansion and contraction. Two very practical papers present the development of soil grouting, where permeation, fracture, replacement, jetting and other grouting techniques are utilized. The papers by Lees with Chuaqui and Warner present experience with ultrafine and other commonly used grout materials. Methods to measure and monitor the injection process and verify production progress are discussed.

Feb 10, 2003

By J. Wiedenroth

Since the end of the 1970s Pipe Conveyors have become increasingly important for conveying bulk materials because they have some specific advantages over conventional troughed belt conveyors. FLSmidth KOCH Pipe Conveyor represent the marked-leading know how of the former KOCH Transporttechnik GmbH, which belongs to the FLSmidth Group since January 2007. Pipe Conveyors from FLSmidth KOCH are already being used successfully at more than 260 locations around the world. Their special properties, their extreme flexibility, the horizontal and vertical changes in direction without transfer points, the small space requirement, the low-noise running and their optimum protection of environment and material without any additional casing mean that Pipe Conveyors can provide transport solutions that are often far superior to other conveying systems. The utilization of these many advantages will be illustrated in the following example of the world?s longest Pipe Conveyor at Cementos Lima, the Peruvian cement producer.

Jan 1, 2010