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By Carlos Magno de Lima Leonel

O presente trabalho teve como objetivo comparar o desempenho de processo entre espirais convencionais e espirais de grande diâmetro, na concentração de minérios de ferro. Foram realizadas campanhas de testes para levantar os dados necessários para comparar os dois modelos de espirais em estudo. Os resultados mostraram que as principais variáveis que afetaram a eficiência de separação nas espirais foram a abertura dos lemes e a concentração de sólidos na alimentação. A espiral de grande diâmetro obteve resultados melhores, mesmo sem a utilização de água de lavagem, porém mais testes serão necessários para uma conclusão definitiva.

Aug 16, 2017

By Márcia Maria Salgado Lopes

Este trabalho busca avaliar a utilização do resíduo de granito, como pigmento, em tintas para construção civil, que atendam aos requisitos de uma tecnologia social. Inicialmente, caracterizou-se o resíduo, para determinar a potencialidade de uso desse material em tintas. Para a produção das amostras de tintas, definiu-se um modelo experimental, baseado na variação das proporções dos componentes da mistura. Nesse modelo, as proporções de pigmento e resina foram definidas de acordo com a faixa de variação de PVC (Pigment Volume Concentration) esperada para uma tinta fosca. Já a proporção de água variou, de modo a se manter a viscosidade dentro de uma faixa que permitisse a boa aplicação da tinta. Em seguida, foram realizados ensaios de determinação do poder de cobertura e resistência à abrasão para cada uma das amostras. Verificou-se que, o resíduo de granito apresenta características que o habilitam a ser utilizado, como pigmento, em tintas. Notou-se ainda que foi possível produzir misturas com elevados teores de sólidos e que o PVC exerceu grande influência sobre o desempenho das tintas. Entretanto, os resultados dos ensaios de determinação de desempenho indicaram que em nenhuma das misturas produzidas foi possível atender simultaneamente aos requisitos estabelecidos pela ABNT NBR 15079:2011.

Oct 30, 2017

By John F. Papp

The Bureau of Mines has sampled microstructure of low-pressure flat flames by mass spectrometer for normal methane-oxygen-argon and for methane-oxygen-argon-bromotrifluoromethane flames. The physical and chemical phenomena, and the method of analysis of mole fraction data to evaluate net reaction rates are here considered in detail. Included is a computer program listing with output on one flame. Chemical species considered are CH4 , CO, CO2, H, H20, OH, Ar, H2, O2 , O, H2CO, CH3 , CF3Br, HF, HBr, Br, CH3Br, HCO, F2CO, CH2 CF2 , H02.

Jan 1, 1975

In several European countries, including Russia, it has become economically attractive to utilize peat as a fuel for power generation, the production of metallurgical coke, the production of fuel briquettes for the domestic market and low-Btu gas. Although the economic base and availability of energy supplies in Europe is much different than it is in Canada, regional economics here may warrant the development of peat as an alternative source of energy. Canadian peatlands cover several thousands of square miles and have historically been considered as waste land. Now, with the increasing costs of other energy sources, it is apparent that fuel peat should be re-evaluated as a potential energy resource. A nation-wide inventory of peat deposits has been prepared and reserves evaluated for some of these areas where field surveys have been carried out. The paper describes alternative mining methods developed to meet some of the various conditions encountered on virgin peatland . These mining techniques are generally based on current peat technology exercised in other parts of the world and would be applicable in some of the peat regions of Canada. Cost estimates have been prepared for peat production in regions of Canada, and the socio-economic aspects of a large-scale fuel peat operation are discussed. Several potential utilization schemes have been described, with particular emphasis on electric power generation. The paper makes recommendations for steps to be taken in the development of a fuel peat industry in Canada.

Jan 1, 1978

By J. C. Allan

THE purpose of this paper is to outline the pogress made in the development o the gravity separation method o ore dressing known as Sink-and-Float, which, in the opinion of the writers, has now reached a stage justifying the claim that this new method marks a highly important advance in the technique . The essential feature of the newest development of this process is the extremely accurate separation achieved. This is responsible for higher extraction in the sink-and-float unit on coarse sizes and, in consequence, for substantially higher overall recoveries. Whilst this is the most remarkable feature of the new process, it has further important contributions to make to ore dressing under the following heads: (1) The introduction of the sink-and-float separator as a buffer helps to iron-out irregularities in the mill feed. By supplying a concentrate of constant grade to the flotation section, the process also indirectly improves overall recovery. (2) The addition of a sink-and-float unit to an existing mill results in substantial increase in capacity at low per ton capital cost. (3) Where the plant can be installed underground for the pre-treatment of low-grade ores, there is a saving in hoisting costs, and excellent 'fill' is provided near the point of use. ( 4) Low-grade mixed oxide-sulphide copper ores may be pre-concentrated, thereby producing a flotation feed sufficiently rich to render the oxide residue from such flotation economic for subsequent treatment by leaching or other methods. (5) Application of the process eliminates hard gangue constituents which cause high grinding costs, or gangue constituents which adversely affect flotation. The plant is compact and easily controlled. No highly skilled operators or expensive reagents are required, and the labour and power per ton are low. The separator is extremely flexible, working equally efficiently on any throughput up to its maximum capacity.

Jan 1, 1940

By WILLIAM BOWIE

IN most human endeavors a knowledge of the terrain is essential to the effective carrying out of projects, but no line of work is more dependent on maps than theoretical and applied geology. Maps of a kind do exist for all of the area of the United States, but most of them are crude affairs and of little use in engineering, planning, and scientific research. Topographic mapping in the United States was initiated on a national scale by the U. S. Geological Survey and the organizations that were merged in its creation to make base maps for geologists. Their work could not be effectively done then and cannot be effectively done now without maps that accurately delineate the earth's surface. The distribution of the rock masses that contain valuable mineral bodies, or that by their intrusion brought them into existence, is the first step in a study of the mineral resources of the nation. This work requires three-dimensional maps, that is, topographic maps on which the land forms are shown by contours.

Jan 1, 1938

By F. R. Archibald

Introduction It is the purpose of this paper to review the subject of roasting as preparation of refractory gold ores and concentrates for cyanidation, with particular reference to operations at the mill of Beattie Gold Mines (Que.), Ltd., Duparquet, Quebec. Two earlier papers relating to the Beattie roasting operations are cited as background to the ? present discussion, and more general reference is made to other publications relating? to geology and metallurgy at Beattie. The Beattie roasting plant was built in 1937 as an addition to the existing flotation and cyanidation plant to permit complete processing of the ore at the mine property. Previously, the flotation concentrate had been cyanided, yielding 70 per cent of the gold values, followed by re-flotation of a concentrate from the cyanide residue. This re-floated residue was shipped to a smelter for recovery of gold values unavailable from direct cyanidation. The roasting plant itself is of interest through application in its design of multiple-hearth roasters and a Cottrell plant for separate recovery of dust and arsenic. In the laboratory and plant studies that accompanied development of the plant into a dependable and efficient working unit have been found principles and ideas applicable to other roasting 'problems. Before enlarging on these aspects relating particularly to the Beattie problems and plant, brief consideration is given to roasting in general.

Jan 1, 1949

By W. Z. Choi

In our previous work, a population balance model describing the simultaneous processes of size reduction and mineral liberation has been developed. The experimental verification of this model, however, has been limited to a binary mineral system containing only one composite particle class. When considering multiple classes of composite particles, the estimation of model parameters becomes much more difficult. In the present work, a procedure for estimating model parameters for a multiple composite class model has been developed. Emphasis is placed on the direct experimental determination of these parameters. The physical significance of the breakage rate function and the liberation function in characterizing the liberation process is also discussed.

Jan 1, 1987

"The development of non-destructive testing (NDT) methods for deep foundations occurred in several parts of the world, gradually coming together into the present state of the art. The compilation of this brief NDT history is the best effort of several knowledgeable members of the Deep Foundations Institute (DFI) Drilled Shaft Committee, coupled with the recollections of several historically important contributors to the science. It is not intended to be exhaustive, but rather concentrates on the origins of the methods in common use and on which this manual focuses.Modern NDT methods, and the spread of knowledge about them, have expanded through application to real foundations projects by the original researchers, sometimes inspired by their own curiosity, sometimes to respond to the cost and time limitations imposed by static testing, and sometimes to address the questions raised on research projects funded by large government agencies such as the Federal Highway Administration (FHWA) in the USA, and various European transportation agencies. Initial attempts were primitive by today’s standards, and equipment limitations often restricted successful application to relatively simple cases. As electronics improved and confidence in them increased, the early researchers began commercial promotion of their methods, published their findings in professional journals, and shared experiences at conferences held by such groups as the DFI, the International Association of Foundation Drilling (ADSC), the International Conferences on the Application of Stress-Wave Theory to Piles and other venues such as ASCE and Transportation Research Board (TRB) conferences.NDT methods were developed to fill a need to assess the quality assurance of deep foundation elements. New pile types and higher design loads prompted engineers to verify the safety of their foundations via additional testing during construction. Static load testing was the traditional method to assess performance, and this method has been used for centuries and perhaps even millennia.Relatively recent alternatives to static load testing for determining the capacity of drilled shafts include the bottom load test method. This method uses a jack embedded in the lower portion of the pile (bottom load test) and was first reported to be used from Canada in the early 1970’s (Gibson& Devenny 1973). The concept immediately caught on in Israel, where it was used as a quality control measure for small-diameter piles drilled in rock (then a new technology). The method was later patented in the US by Jorj Osterberg, and offered as a commercially available service in thelate 1980s (Osterberg, 1989)"

Jan 1, 2004

By J. W. Butwell

Anaconda has been active In the Bingham mining district near Tooele, Utah since 1914 when the company acquired International Smelting & Refining Co. Over the years both custom ores and complex Pb-Zn-Cu ores from the district were milled and smelted at International. In 1948 Anaconda acquired the property that covers the present Carr Fork ore body. Since that time active exploration took place in the 50's followed by detailed geological evaluation in the 60's. Convinced that high grade Cu deposits would be found at depth, a deep drilling program commenced in the late 60?s, with intersection of the ore zone in 1969. Following extensive deep drilling in the early 70?s, a feasibility study was conducted in 73-74 with board approval given Sept. 6, 1974. The 9,000 t/d mine-mill complex was budgeted at $217 MM over a 5 year schedule with start-up in Sept., 1979. The following discussion includes the concentrator and surface facility portion of the budget or approximately $60 MM of the scope. Special emphasis will be made on equipment selection and layout.

Jan 1, 1980

By ALEC CROWELL

This brief summary of oil and gas developments in Alabama, Florida and Georgia has been made possible through the courtesy of Stewart J. Lloyd, Assistant State Geologist of Alabama; Herman Gunter, Director, Florida Geological Survey, and Garland Peyton, Director, Georgia Department of Mines, Mining and Geology.

Jan 1, 1946

By Jurgen H. Kleinau

This paper details Keeler/ Dorr-Oliver's experience with the application of fluid bed combustion technology to the burning of coal-mining waste. The designs of two stage fluid bed combustors/dryers are demonstrated as useful in the drying of coal, slag and coke, using coal and coal refuse (gob) as fuel. Anthracite mining refuse (culm) is more than abundant in Northeastern Pennsylvania. After demonstration at Shamokin, Pennsylvania, a full commercial-sized fluid bed boiler using culm is used for district heating in Wilkes-Barre, Pennsylvania. Limited research work has shown the utility of using fine coal as filter aid in sludge in¬cineration. With the rising avenues of the suitability of coal as auxiliary fuel in fluid bed sludge incineration, an expansion of these concepts combines the use of coal or coal refuse as filter aid and auxiliary fuel. Lime¬stone addition controls SO2 emission.

Jan 1, 1985

By M. Dupuis

In the present study, the heat balance of the Hirakud smelter aluminium reduction cell has been accurately assessed using only a surface thermocouple and a pyrometer, As it is well known that using a single linear or quadratic relationship to estimate the heat flux from the measured surface temperature does not provide the accuracy required to close the cell heat balance, this approach was not used in this study, Instead, the fundamental natural convection and radiation heat flux equations were used systematically for each measurement point, Practically, this means that the ambient air temperature and at least one ambient radiative temperature must also be known in addition to the surface temperature for each measurement point. Sometimes, the radiative heat flux could not be accurately estimated using a single ambient radiative temperature, In those cases, a more accurate estimation based on two ambient radiative temperatures and corresponding view factors has been used instead, It turns out that although at least three temperature measurements are required to estimate a single heat flux, it takes a lot less time to make those temperature measurements using a pyrometer than directly measuring the heat flux using an expensive heat flux meter, Furthermore, no loss in accuracy was detected when using this approach as the cell heat balance could be closed within 5%, the level of accuracy typical of cell heat balance assessment using heat flux meter.

Jan 1, 2004

By Fernanda de Lima Menezes

O biodiesel, obtido a partir de um éster e um álcool na presença de um catalisador, é produzido pela reação de transesterificação e tem como coproduto a glicerina. A produção de biodiesel da Petrobras Biocombustível tem, em uma de suas etapas, a lavagem dos produtos para remoção do catalisador básico, metilato de sódio, por meio da reação de neutralização com ácido clorídrico. Devido a essa prática, a glicerina obtida é acidificada e contêm resíduos de cloretos, o que leva à corrosão localizada dos aços utilizados em determinados pontos do processo de produção. Dessa forma, o presente trabalho avaliou a resistência à corrosão do aço austenítico 317L e do aço lean duplex 2304, em meio de glicerina acidificada contendo cloretos. Todas as medidas foram conduzidas a 64ºC, visando simular as condições de operação da empresa. Para o estudo em questão, utilizou-se as técnicas de potencial de circuito aberto (OCP), polarização potenciodinâmica e microscopia eletrônica de varredura (MEV). As análises mostraram que o aço AISI 317L obteve menor potencial de pite que o SAF 2304, logo foi menos resistente. Por meio do MEV foi possível confirmar a presença dos pites, sendo que as cavidades presentes no aço AISI 317L foram mais numerosas e profundas que as observadas no aço SAF 2304.

Jan 16, 2018

By H. K. Najarian

AT Josephtown, Pa., on the south hank of the Ohio River about thirty miles northwest of Pittsburgh, is the Josephtown electrothermic zinc smelter, which operates as a custom smelter receiving both domestic and foreign concentrates. Constructed in 1930, the plant was designed to produce zinc oxide and to process 124 tons per day of zinc concentrate obtained mainly from the Company's New York State mines. Zinc condensing equipment was developed in conjunction with the St. Joe electrothermic. furnace and commercial production of zinc metal started in 1936. Expansion of the plant and equipment during 1939 and 1940 brought the processing. capacity to upwards of 300 tons of concentrate per day; and the plant operated at peak capacity during the war years, earning the Army-Navy "E" award and three subsequent stars. A postwar plant expansion is now under way, designed to increase the capacity to 500 tons per day of concentrate, with an estimated daily production of 160 tons of zinc metal of various grades, about 100 tons of zinc oxide, and 425 tons of sulphuric acid as major products.

Jan 1, 1947

By W. J. Langford

"Conventional design criteria assume that the fracture strength of a structural material exceeds its yield strength. Fracture below the design load is not expected, y et many structures have failed in this way. The causes of the fractures are almost always discontinuities such as cracks and welding defects. Linear Elastic Fracture Mechanics (LEFM or simply 'fracture mechanics') provides an analytical framework for assessing the influence of sharp defects on the load-bearing capability of a structure. Fracture mechanics techniques have reached the point of acceptance by ASME Design Codes for nuclear components, and ASTM Standards now include well-defined rules for measuring fracture toughness. Starting with a simple equation which relates applied stress and crack size, the influence of the material's thickness and yield strength can be calculated. Thus, the size of defect which will cause failure under the applied stress may be determined. Armed with this information, the metallurgist can assess the safety of a structure from the viewpoints of non-destructive testing standards, construction standards and conditions of operation throughout its service life."

Jan 1, 1976

By Klaus Schönert

In the analysis of comminution processes, it is necessary to have a detailed knowledge of such sub-processes as: (i) The transportation of the particles to the zone where they are stressed, (ii) The stressing of the particles to a level high enough for breakage, (iii) The removal of the fragments that are smaller than the limit size from the grinding zone, and (iv) The prevention of agglomeration of the fine fragments. The breakage phenomena of particles is the most difficult sub-process to understand. It can be understood only by applying the principles of fracture physics to obtain information about the stress-strain field in particles which are loaded either by compression or by impact, and by using this theoretical knowledge to interpret experimental results obtained from single particle crushing studies. It is not only of academic interest to know how a particle breaks, but also it is important for practical applications because it provides a basis for evaluating both the direction and limitation for any potential comminution improvement.

Jan 1, 1971

By Robert E. Sorenson

EXPLORATION for deep-seated orebodies in the Silver Belt area of the Coeur d'Alene mining district is complicated by meager surface expressions of diagnostic criteria, lack of knowledge of the significance of specific alteration phenomena, and the great expense involved in the exploration for ore shoots, the tops of which often occur near sea level elevation or below and as much as 4000 ft or more below the surface. Except for the early studies of Ransome and Calkins in 1903 and 1904,[1] little geological work was done in the Coeur d'Alene district for many years, and it is only during the last 15 to 20 years that complete and careful geological mapping has been applied to most of the mines in the area. Much early information, which now would prove invaluable, is lost in hundreds of miles of caved and inaccessible mine openings not mapped by mining geologists. In more recent years mining geology has become a tool of greater use in the district, and some measurable progress is being made in the accumulation of observations that are adding gradually to the knowledge of ore deposits in the district.

Jan 7, 1951

By J. J. Demeter

As part of its work on converting coal to fluid fuels, the Federal Bureau of Mines has been studying the synthesis of liquid fuels from carbon monoxide and hydrogen by Fischer-Tropsch synthesis. A fluidized bed of nitrided, fused-iron catalyst has been operated successfully to produce high yields of oxygenated compounds. Trouble-free operation continued for over 800 hours, and the test was terminated voluntarily. About 85 percent of the fresh feed was converted when the unit was operated at a space velocity of 500 hr.-1, a 12:1 recycle-to-fresh-feed-gas ratio, a 300-p. s. i. g. pressure, and a temperature of 252° C. When operating at a fresh-feed-gas space velocity of 1,000 hr.-l and a 9:1 ratio of recycle to fresh gas, conversion of fresh feed was 68 percent, and the product yield was 235.9 grams per cubic meter of synthesis gas converted. The oxygenate and C5 and heavier hydrocarbon yield was 110.6 grams per cubic meter of gas converted, 83 percent of this was oxygenates. The atom ratio of N:Fe of the catalyst, initially 0.455, decreased to 0.288 by the end of the 800-hour experiment. Nevertheless, the yield of oxygenated compounds per cubic meter of H2 + CO converted at the end of the run was approximately the same as that obtained 500 hours earlier with identical operating conditions. X-ray analysis of the discharged catalyst indicated that only ?-iron carbonitride was present. Sieve analysis of the discharged catalyst indicated that only 2 percent of fines was produced during the reduction, nitriding, and synthesis.

Jan 1, 1959

By F. Ikumapayi

Hydrogen peroxide production was measured during the grinding of a complex sulfide ore, and its oxidizing effect on solid surfaces was investigated using Fourier transform infrared spectroscopy (FTIR) with diffuse reflectance attachment measurement. In turn, an attempt was made to correlate the formation of hydrogen peroxide, surface oxidation and sphalerite flotation. Additionally, in order to predict and minimize detrimental production problems due to the recycling of process water in sulfide ore processing, the effects of major components of calcium and sulfate species present in recycled process water and the effect of temperature on sphalerite flotation were investigated through bench-scale flotation tests using complex sulfide ores. The significance of process water species in flotation was studied using tap water, process water and simulated water containing calcium and sulfate ions. Formation of hydrogen peroxide was revealed during the grinding of the complex sulfide ore, and its formation was counteracted by diethylenetriamine (DETA). The FTIR spectrum of the pulp solid fraction showed varying degrees of oxidized surface species, which are related to the concentration of H2O2 analyzed in pulp liquid. Bench-scale flotation using two different complex sulfide ores showed that sphalerite recovery is better in process water than in tap water. Flotation results also indicated a varied recovery of sphalerite at different temperatures in either tap water or process water.