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By Karen Leão dos Santos

A borracha sintética (SBR) é amplamente utilizada em indústrias de pneus combinada a cargas de reforço para melhoria das propriedades do elastômero puro. Atualmente, as cargas que apresentam melhor capacidade de reforço em elastômeros são a sílica e o negro de fumo. O presente estudo buscou avaliar o desempenho de compostos de borracha sobre as características de resistência ao rolamento, tração em piso molhado e resistência à abrasão, em função das quantidades de sílica e de negro de fumo. Foram realizados ensaios mecânicos e dinâmico-mecânicos, e, a partir dos resultados obtidos, concluiu-se que a utilização das diferentes cargas de reforço no composto de borracha está associada ao tipo de uso a que se destina o pneu.

Aug 17, 2017

By Rafael Lopes

O rendimento metálico é um dos principais indicadores de processo de laminação de longos, uma vez que tem influência direta na redução do custo de produção, sendo fundamental no atual cenário econômico da siderurgia brasileira. Em função disso faz-se necessário identificar as principais causas de perdas metálicas para aumentar o índice desse indicador, utilizando a metodologia DMAIC. Como resultado houve o aumento de 1,22% alcançado pela otimização dos parâmetros de processo do tratamento térmico, redução do comprimento do descarte da cabeça e cauda da barra na tesoura e melhoria na automação das válvulas do sistema de têmpera e autorevenido.

Aug 17, 2017

By R. J. F. Goodfellow

Many underground projects now include preparation of a Risk Register through planning and design as a tool for project and risk management. There is still significant discussion within the industry as to whether and how to best present the Risk Register through the bidding process and the construction phase of a project. While the ITIG Code of Practice for Risk Management of Tunnel Works recommends this approach of continuity in risk management procedures, it is silent on the specifics of how this should be achieved. This paper will explore the perceived benefits and disbenefit of including the project Risk Register with bid documents; format and content that should be transferred and lessons learned using the case history of bidding and early construction phase of the Bi-County Water Tunnel in Montgomery County, MD

By Axel Sahlin

Jan 1, 1898

By M. Hochenhofer

Keywords: desulfurization, mathematical model, slag reaction To produce ferroalloys like ferro-nickel for alloying purposes in a quality that meets the requirements of today?s steel industry, refining processes like desulfurization and dephosphorization are indispensable. The performance of desulfurization-treatment by slag reaction depends on various parameters, such as: sulfide capacity and viscosity of the slag, sulfur distribution between metal and slag, activity of sulfur in melt and movement of melt. Within this work, the combined influences of these parameters on the desulfurization of a ferro-nickel alloy were examined. As a basis for this examination, a mathematical model, based on data from plant trials, was created. This model demonstrates the relationship between desulfurization rate and initial values of the above mentioned parameters. With this model the relevant parameters were evaluated and assessed concerning their influence on desulfurization.

Jan 1, 2005

By R. C. Milici

The primary factors that determine the marketability of coal from various supply centers in the U.S. are coal quality and supply; i.e. low sulfur, moderate- to high- Btu coals have large market areas when compared to less expensive but poorer quality coals. Price is the major factor in the competitive marketing of similar coal products. Good quality, (moderate- to high- Btu, low sulfur) coals from the Powder River and central Appalachian basins are marketed over large areas of the country, and central Appalachian coal is widely distributed in foreign markets, primarily as coking coal. In contrast, poorer quality bituminous coal (low calorific value and/or high sulfur) from the Illinois Basin, northern Appalachian Basin, and lignite from the Gulf Coast is marketed in or near the States in which it was mined even though the price at the mines may be lower than mine prices for central Appalachian coal. Widespread distribution of sub-bituminous Powder River Basin coal is enhanced by its exceptionally low mining costs, which offsets transportation costs to distant markets.

Jan 1, 2001

By Albert Adu-Acheampong

Fairmount Mineral's Maiden Rock underground sand mine historically delivered air to ventilate diesel-powered equipment at its working faces through high-resistance, 381-mm- (15-in.-) diameter PVC distribution lines. In support of plans for expanded production, three new, low-resistance ventilation design alternatives were analyzed. The study determined that adequate ventilation for expanded production was possible with various commercially available, high-volume/ low-pressure fans combined with a systematic layout of control structures. The recommended redesign was implemented in 2001, resulting in a significant increase in flow volumes and a noticeable improvement in the mine environment.

Jan 1, 2008

By Kathleen A. Altman

"This paper supplements the information provided annually at the Canadian Mineral Processors Operators Conference regarding the education of Mineral Processors in Canada. The purpose of the paper is to provide information regarding the engineering accreditation process in the United States and the universities that offer programs in Mineral Processing and Extractive Metallurgy in the U.S.There is a critical shortage of trained Mineral Processors and Mining Engineers world wide. The Society for Mining, Metallurgy and Exploration (SME) formed a task force to evaluate the national needs for trained engineers and to track the number of engineers who graduate from U.S. universities each year. The statistical information for Mining Engineers is well-developed. The current effort is to assemble similar information regarding students who graduate with expertise in Extractive Metallurgy and Mineral Processing as well as to explore the limitations of the accreditation system in the United States and its impact on the education of Mineral Processors. The long-term objective is to develop a data base regarding Mineral Processing programs and Mineral Processing graduates that is as complete as the one that has been maintained by the Canadian Mineral Processors.INTRODUCTIONIn the United States engineering curricula are accredited by ABET, which was formerly known as the Accreditation Board for Engineering and Technology. The objective of ABET accreditation is to ensure that educational programs in applied science, computing, engineering and technology meet quality standards set in conjunction with the professional organizations that represent professionals in the industries which hire students graduating from those educational programs. For example, the Society for Mining, Metallurgy and Exploration (SME) is the lead society for accrediting Mining Engineering programs in the U.S. For Materials Science and Metallurgical Engineering programs, the lead society is The Mineral, Metals and Materials Society (TMS). SME is a cooperating society for accrediting Metallurgical Engineering programs. Cooperating societies for the accreditation of Materials Engineering include the National Institute of Ceramic Engineers (NICE), the American Institute of Chemical Engineers (AIChE) and the American Society of Mechanical Engineers (ASME)."

Jan 1, 2008

By G. H. Lewis, C. L. Krcil, N. S. Harding, D. E. Havekotte

Introduction Limestone injection work was completed in a 440-kW (1.5-million Btu per hour) pilot-scale combustor in preparation for a 50,000-kg/h (110,000-lb per hour) industrial steam boiler limestone injection test program. The main objectives were to: (1) identify the important variables that affect sulfur capture, (2) determine the maximum SO2 removal, and (3) determine the effect of limestone addition on furnace operability and heat transfer. A more detailed report is given by Lewis et al. (1985). The test program was divided into two phases. The objectives of Phase I were to determine the important variables that affect SO2 reduction and to investigate the effect of limestone addition on combustor operation and heat transfer surfaces. The objective of Phase II was to determine, using only the important variables identified during Phase I, the conditions that resulted in the greatest sulfur dioxide reduction. Phase I Test program Using one limestone, five variables were identified as having an effect on SO2 reduction. These are noted with their respective ranges: heat release rate [103 to 166 kW/m3 (10,000 to 16,000 Btu per hour-cu ft)], Ca/S molar ratio (0 to 3), flue gas oxygen concentration (3% to 5%), additive particle size [90% -150 µm (-100 mesh) and 90% -45 µm (-325 mesh)], and burner stoichiometry (SR = 0.75 and >1.15). A 2.3% sulfur northern West Virginia coal, pulverized to a nominal grind of 70% -75 µm (-200 mesh), was burned for the tests. The limestone used was obtained from a Maysville, KY, quarry and contained 51.75% (wt) CaO. An 11-run statistically designed program (plus three duplicates) was used to screen the five variables. The effect of limestone injection on the combustor heat transfer surfaces was determined by comparing the heat transfer rates through a slag panel and fouling probes during periods with and without limestone injection. Combustor operation was determined by noting any operating problems that occurred during the tests. Test procedure After furnace wall temperatures had stabilized at operating conditions, heat transfer surfaces (slag panel and fouling probes) and the convection section were blown clean, and a four-hour test was begun. The

Jan 12, 1986

The selection of the mining fleet can have as much of an effect on the efficiency and effectiveness of an operation as the mining method. This is not to say that inefficiencies are only attributable to inappropriate equipment selections, these aspects have many factors but are not the subject of this paper.This paper will give an overview of equipment selection processes that have been utilised to date. It will also look at the increase in application of study programs/simulations from an aspect of accuracy, as well as the importance of enabling the analysis of multiple sensitivity scenario planning. An aspect that is increasingly important in project planning with commodity market movements.Another aspect that is increasing in popularity is that of automation, what effect does this have on equipment selection? What additional aspects need to be taken into consideration when assessing Automation of equipment from the beginning of a project as well as introduction into an operating mine?Once the selection process has been finalised and equipment implemented, how do we, as an industry, 'close the loop' through analysis of estimated versus actual equipment application?

Dec 6, 2010

By E. Stiakakis

The paper presents a geotechnical simulation of the "Mavropigi" open pit mine (Western Macedonia Lignite Center, Greece), using the finite element method. The simulation was based on the initial planning of the pit using Mohr-Coulomb and Soil Hardening models. Results indicate high stability factors as well as the magnitude of the expected horizontal displacements and floor heaving. However, these deformations do not influence decisively the overall stability unless locally adverse tectonics are encountered. Results can be used in the ongoing update of mine planning and stability evaluation.

Jan 1, 2006

By J. G. Kirby

According to the Bureau of Mines annual survey, there were 319 petroleum refineries in the United States as of January 1, 1957 capable of processing 9,123,674 [ ]-barrels of crude oil daily. This was the first time in eleven years that the total number of refineries increased. The crude throughput capacity of the refineries increased 491,284 barrels daily (6 percent) above the January 1, 1956 capacity. The East Coast and Texas Gulf Coast refining districts accounted for 60 percent of the additional capacity installed. Three new refineries were put into operation on the East Coast during the year with a total daily crude throughput capacity of 154,434 barrels while the other refineries in the district report a net loss in capacity, installing equipment capable of processing 140,000 barrels, but dismantling equipment with a capacity of 150,100 barrels. In the Texas Gulf Coast district, one new refinery with a daily crude oil capacity of 5,000 barrels was placed in operation in 1956 and 143,700 barrels of crude capacity was added to existing refineries. The capacity of the average refinery to process crude oil increased from 27,145 barrels daily to 28,601 barrels in 1956.

Jan 1, 1957

By Marlon José Zanotto

O objetivo deste trabalho é comparar o uso da liga~mãe Al-5Ti-1B e dos sais de fluortitanato de potássio (K2TiF6) e fluorborato de potássio (KBF4) no refino de uma liga de alumínio de pureza comercial. Os resultados demostram a eficiência da liga-mãe no refino de grão quando adicionada em quantidades acima de 0,6% em peso. No entanto, para o sal de boro, não houve refino de grão na mesma quantidade e no dobro da porcentagem. Já para o sal de titânio ocorreu refino de grão, provavelmente devido à presença de boro residual no alumínio puro comercial.

Aug 17, 2017

By Breno Totti Maia

Os convertedores BOF, em função das condições operacionais e mesmo de sua localização, sofrem variações de parâmetros cujos seus efeitos sobre o metal líquido nem sempre são considerados. O presente trabalho investigou dois aspectos: a pressão ambiente no interior do convertedor e a temperatura do oxigênio no reservatório estagnante. Os resultados mostram que a temperatura de oxigênio apesar de alterar as propriedades de saída desse gás tem pouca influência na penetração de jato. Já a pressão ambiente do BOF tem grande influência na penetração de jato, e leva um dilema nos dimensionais de bocais de lança relativo aos jatos subexpandidos e sobrexpandidos.

Aug 17, 2017

By Michel C. Frippel

This section of the Minerals Yearbook reviews the minerals industries of 27 countries: the 12 nations of the European Community (Belgium, Dermark/Greenland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, Spain, and the United Kingdom); 6 of the 7 nations of the European Free Trade Association (Austria, Finland, Iceland, Norway, Switzerland, and Sweden); Malta; the 8 Eastern European economies in transition (Albania, Bulgaria, Czechoslovakia, Hungary, Poland, Romania, and Yugoslavia); and the U.S.S.R. Western Europe Western Europe [loosely defined to include the 12 nations of the European Community (EC) and the 7 nations of the European Free Trade Association (EFTA)] is the single largest trading area and consumer of raw materials in the world. If Western Europe was at one time an important mining sector, it has now increasingly relegated the role of supplying minerals for its minerals processing industry to the more minerally endowed countries in North and South America, Africa, and Australia. In this regard, Western Europe is the most important determinant of raw materials consumption (and thus, indirectly, raw materials production). Western Europe has significant reserves of industrial minerals but has limited availability of metalliferous raw materials. It, therefore, imports significant quantities of the latter and ranks along with the United States and the U.S.S.R. in the production of refined metals. Nonetheless, there is an inherent tendency to underestimate the importance of Western Europe in the world of minerals, both as a minerals processor and raw materials buyer. The reason for this is that Western Europe is generally thought of on the basis of individual nations rather than as a whole. Viewed in this limited context, the United States, the U.S.S.R., and Japan appear to dominate the world economy. Viewed as one regional area, however, Western Europe includes the fourth (FRG), fifth (France), sixth (United Kingdom) and seventh (Italy) largest economies of the world, all bordering on one another. With the remaining 15 EC and EFTA countries, Western Europe has a land area approximately 40 % of that of the United States, exceeds the U.S. population by 50 % and has a gross domestic product about the same as that of the United States.

Jan 1, 1993

By H. Jehn

Like some other Pt-group metals palladium shows a low but considerable solid solubility of oxygen, which was found already from oxidation studies. The oxygen solid solubility of palladium in equilibrium with gaseous oxygen has been investigated at 900 - 1300 °C in oxygen (665 mbar) and air by gassing and analyzing polycrystalline samples. The 0-concentrations range from 40 to 90 ppm and decrease with rising temperature. The isobaric solubility can be represented by the least-squares fit log c0 = 0.5 log p02- 0.32 + 920/T (c0 in wt. ppm, p02 in mbar, T in K). The thermodynamic data of the exothermic solution reaction are calculated to ?H°= -17.6 kJ?mol-1 and ?S° -76.5 J?mol ? K-1. The behaviour of palladium in an oxygen atmosphere is characterized by the simultaneous reactions of the solution of oxygen in the metal and the formation and evaporation of volatile oxides besides the pure metal evaporation.

Jan 1, 1984

Jan 1, 1967

By I. J. Duckworth

During the last twenty years computers have be-come widely used to assist with the simulation and design of large scale, primary ventilation systems. However, to date there are few computer programs available to help with the modeling of auxiliary ventilation in dead-end headings or tunnels. This paper presents the results of the first year of a research and programming study dedicated to the development of a user-friendly duct simulation tool. Included is a literature review that summarises publications on duct leakage and resistance, on previous programs developed for the simulation of airflow in ducts, and case studies on extended ductlines in mines and tunnels. The methodology behind the development of Ductsim, a Windows based simulation program is presented.

Jan 1, 2000

By John W. Gunnett

The purpose of this afternoon’s presentation is to highlight the investigative proce dures employed to complete an engineering audit of a mining operation. Skelly and Loy has been retained to perform operational audits throughout the nation’s coal fields, The need for such studies is generally associated with long term coal supply contracts and is typically initiated by the utility company. However, a number of projects have been commissioned by mining companies while others have been jointly funded by the utility and mining company.

Jan 1, 1992

Separation of Minerals Using Electrical Fields The mineral processing industry requires alternative separation techniques to help deal with rising energy costs and decreasing ore grades. Dielectrophoresis is one possible technology. It uses non-uniform electrical fields to separate particles on the basis of their permittivity. In order to determine its viability, the dielectrophoretic force was measured for individual chalcopyrite particles in ethanol. The measurements were made by attaching the individual particles to glass fibres and measuring how far they were deflected by a non-uniform electrical field. Six sizes of chalcopyrite particles were tested and the force was found to increase as a function of particle radius cubed. The particles were also positioned at different points in the field in order to determine the effect of the electrical field gradient. The force was found to increase with the inverse cube of the distance from the centre of the particle to the pin electrode. With the effect of these parameters fully characterised, the single particle test cell can be used to determine the permittivity of single particles of various composition.

Sep 13, 2010