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By Rodrigo Alves Caetano

A Usiminas, maior siderúrgica latino-americana fornecedora de aços planos, tem dedicado grandes esforços para oferecer materiais mais adequados para as diferentes demandas do mercado, desenvolvendo novos tipos de aços para utilização em carrocerias veiculares. O objetivo deste estudo foi caracterizar o comportamento de dois produtos Usiminas, o aço DP780 galvanizado por imersão a quente e o aço TRIP780 eletrogalvanizado, ambos com espessura de 1,50 mm, revestimento zinco puro e camada de 50 g/m² por face, com base em análises metalográficas, ensaios de tração, ensaios de estampagem e ensaios Bake Hardening (BH) e Aging Index (AI). Os resultados destas avaliações mostraram que os aços TRIP780 e DP780 tiveram performances excelentes em todos os modos de estampagem avaliados, além de boa capacidade de endurecimento após pintura (efeito BH). Tratam-se, portanto, de boas opções para aplicação em peças da carroceria, principalmente em componentes que requeiram elevada resistência mecânica.

Aug 16, 2017

Jan 1, 1949

By K. E. Kolm, W. H. Langer

Developing natural aggregate resources (sand, gravel and stone) creates environmental impacts. A systems analysis method was designed to characterize the components of the environmental system, identify potential impacts to those systems and evaluate the extent of those impacts. The stepwise method consists of problem definition, data collection, preliminary conceptualization and characterization, additional data collection, data analysis and refinement. The method requires analyzes of various systems making up the environment, including land surface, geomorphic, subsurface and groundwater systems. After system characterization is complete, the method focuses on identifying and evaluating potential environmental impacts to determine acceptable mining strategies.

Jan 1, 2003

By J. H. Lalor

The Olympic Dam deposit was discovered in July 1975 with the intersection of 38 m (125 ft) of 1.05% copper in diamond drill hole RD 1. A further eight holes were drilled with only marginal encouragement to November 1976 when RD 10 cored 170 m (558 ft) at 2.12% copper and an economic discovery was confirmed. The discovery of Olympic Dam is an excellent example of the application of broad-scale scientifically based conceptual studies to area selection combined with the backing of an exploration management willing to support its exploration scientists in testing their ideas with stratigraphic drilling. It also illustrates the persistence required in mineral exploration. The project began in 1969-1972 with the development of a conceptual model for the formation of sediment-hosted copper deposits. This model suggested that the alteration of continental-type basaltic rocks could release copper into solution from which it could be concentrated in favorable stratigraphic positions. In mid-1972, this concept was applied to a review of the Proterozoic and Lower Paleozoic rocks in South Australia aimed at defining targets for stratigraphic copper deposits.

Jan 1, 1991

The Board of Directors on April 18, 1940, adopted a resolution providing that "no person who has been awarded any one of the four medals-Douglas, Saunders, Lucas, and Rand-is eligible for consideration for any other of the four medals " Later in the year the rules for the award of these four medals were revised and, so far as practicable, made uniform The medalists are elected by the Board of Directors, on recommendation of special standing committees of award, appointees on which serve four-year terms and are engaged in the branch of industry represented by the respective awards Under the rules only members of the committees of award are eligible to propose candidates\ for the nomination

Jan 1, 1952

By L. Piga, P. Cipriani, F. Pochetti

High-temperature roasting of alunite in the presence of K2CO3 gives rise to a reaction that results in up to an 80% recovery of its potassium content as K2SO4 by leaching of the roasted mixture. K2SO4 is also generated from the reaction between the added K2CO3 and the SO3 driven off during roasting of the alunite. This limits the environmental and corrosive problems involved in the thermal treatment of this mineral. A solid residue containing mainly aluminum oxide is also obtained. This could be used as raw material for the production of aluminum, as the use of K2CO3 does not introduce different cations than are in the ore. A statistical study was performed on the factors assumed to affect the recovery of potassium, namely, roasting temperature, K2CO3- alunite stoichiometric ratio and leaching temperature.

Jan 1, 2000

By R. P. Rothwell

Instruction by correspondence is certainly one of the most important and useful of modern educational methods. The paper on the " Scranton International Schools," by Prof. Stoek (Buffalo meeting, October, 1898),* gives an elaborate description of a single private enterprise in this direction, ignoring all others, and cannot be said to present a fair or impartial view of

Jan 1, 1900

By Frank T. Weems

The basic operating properties of the DorrClone are discussed and certain metallurgical applications which exploit these properties are presented. An effective method of controlling the consistency of the DorrClone underflow is described.

Jan 8, 1951

By Peter N. Calder, John N. Tuomi

The development of a successful control blasting program for an open pit iron mine in hard jointed rock is described. The objectives and mechanics of control blasting are discussed. Design and implementation procedures, which should have wide application, are given. Small diameter angle hole pre-split blasting, buffer blasting with production holes in front of pre-split lines and in front of strongly defined rock structures, and vibration control of production blasts are dealt with.

Jan 1, 1980

By José Cáceres

Mine To Mill? ? Carlisle(1954) ?The economic of a fund resource with particular reference to mining?. ? Steine(1978) ?Coarser grind may mean lower metal recovery but higher profit?. ? Metalica (1999) ?Mine Plant Integrated Planning?. ? JK (2002) Mine to Mill Strategic Planning ? Camus, Kelebek (2002) ?Management of Mineral Resources: Creating Value in the Mining Business?. ? Caceres (2003) ?Integrating Milling Parameters in the Mining Planning?

May 1, 2006

By T. S. Golosinski, J. Wolski

Procedures are presented for determining the hourly production rate, mechanical and physical availability, utilization, use of availability, and global performance factors for the bucket wheel excavator (BWE) itself, as well as for the system composed for the BWE, conveyors, and stacker. An example demonstrates the flow of calculations. Using available data from mines that use BWE technology, the ranges of values of the BWE performance factors are presented in tabular form. They can be used as a guide during mine planning as well as to evaluate existing systems.

Jan 1, 1987

By M. S. J. Leary, M. J. McPherson, O&apos

This paper introduces a computer simulation that extends the use of microcomputer systems for mine ventilation planning. The program was developed as part of an ongoing study to produce a simulation model that would determine the optimum duties of a main fan and a booster fan without requiring the trial-and-error runs that are necessary with currently available programs. To use the new program, the user specifies the location of one main fan and one booster fan, and the minimum required airflows in any number of working places. The computer determines the fan duties that will maintain the required airflows at the lowest operating costs without causing undesired recirculation. The methodology of the program and an example showing how it can be applied are presented.

Jan 1, 1990

By William E. Spence

Gold was discovered at the Haile mine in Lancaster County, South Carolina in 1827 or 1828, and since that time the mine has been worked intermittently by both open pit and underground methods until its forced closure in 1942 by World War II. Production figures are incomplete, especially for the early years, but the total gold produced is estimated to have been greater than 200,000 ounces. Thus, the Haile mine has been the most productive gold mine in the eastern United States. The upper, residually enriched ores were relatively rich, but the bulk of the production has come from the mining of lower grade ores.

Jan 1, 1978

By George H. Jones

NO STRANGER phenomenon exists in the American mining industry today than the so-called bootleg anthracite industry in Pennsylvania which now produces probably close to 15 per cent of the total hard coal out- put of the State. Instead of being what - was first thought to be a temporary condition, countenanced because of the desperate condition of some of the miners at the depth of the depression. it is thriving now as never before. Re- ports of it have penetrated all over the world, as exemplified by inquiries concerning it in Durban, South Africa mentioned by John C. Cosgrove in his article in the July MINING AND META LURGY.

Jan 1, 1939

By Fred C. Bond

DISCUSSION Milton C. Shaw and Donald R. Walker (Massachusetts Institute of Technology)—For many years the two empirical rules of comminution bearing the names of Rittinger and Kick have been applied to grinding processes to account for the energy required to crush brittle materials. The basis for Rittinger's rule was the thought that the energy to grind a substance went largely into supplying the additional energy associated with the new free surface, while Kick's law was prompted by the concept of dimensional similarity and is a special statement of the concept of constancy of strain energy to cause rupture. According to Rittinger the energy to grind a given volume varies as the change in the square of the mean particle size, v - A (D2), while according to Kick this energy varies

Jan 1, 1953

By Donald W. Frommer

For many years the Bureau of Mines has been con- ducting comprehensive iron ore research programs with the objective of increasing domestic supplies and divising techniques that would enable profitable exploitation of low-grade and complex domestic iron-mineral deposits. Since 1962, much of the Bureau's flotation research at Minneapolis has been concerned with studies on the treatment of low-grade hematitic-goethitic jaspers of the Marquette range, Mich. Ores from Michigan require grinding to substantially minus 400-mesh for liberation that will permit production of quality concentrates. With such fine grinding, diminished flotation effectiveness can be expected because of slime interference. The word "slime" is an ambiguous term. Taggart states "Slimes in an ore pulp are loosely defined as the fine fraction that overflows a desanding separator. . ."

Jan 4, 1964

By Jim Morris, Davin Ishii

The major source of water for Southern Nevada is Lake Mead. However, the existing pump station located on Lake Mead is inadequate for one of the fastest growing areas in the United States. In order to keep up with the increasing demand for water in Las Vegas, a parallel system is being constructed. The intake for this system is being constructed approximately 68.58m (225ft) below the surface of Lake Mead. The lake tap consists of installing casing and secant piles to support the shaft collar, excavating a 21.34m (70ft) deep intake shaft, and installing a3.66m (12ft) diameter steel liner.

Jan 1, 1999

By A. D. S. Gillies

The effectiveness of coal mine face ventilation and the ability of airflow to maintain satisfactory methane and respirable dust levels in the working face area has been studied through the use of scale modeling techniques and underground testing procedures. In particular, consideration has been given to examination of the effects of operation of a high airflow, machine mounted dust scrubber unit on face air patterns. Results obtained through a cooperative study with the Peabody Coal Co. demonstrate that new mining cycles can be considered that increase production efficiency while maintaining satisfactory ventilation conditions.

Jan 1, 1986

By R. Bhaskar

Although the health effects of airborne dust in underground coal mines are well recognized, a lack of understanding remains about the fundamental mechanisms of dust generation, transportation, deposition and dust-lung reaction. This study was intended to contribute to the understanding of dust transportation and deposition mechanisms in underground mine airways. Data from in-mine experiments carried out under controlled conditions in a straight section of a longwall panel with three different airflow velocities and two different types of coal dust (bituminous and semi-anthracite) were used to determine the turbulent deposition rate of dust particles. Measurements of ambient dust concentrations and deposition along the mine airway were obtained and the total dust deposition velocity (rate) was calculated. The deposition velocity of turbulent diffusion was estimated based on the experimental data and theoretical equations. The effects of airflow velocity, particle size, particle density and distance from the dust source on gravitational, turbulent and total dust deposition are discussed along with related conclusions.

Jan 1, 1995

As modern techniques of Petroleum Exploration and Development are rela-tively new in Australia,2 the alien terms "Mud Logging" and "Core Analysis" will bear explanation. Mud Logging and Core Analysis are two of the Petroleum. Industryts most useful "tools" in the successful search for, and development of, commercial oil and gas deposits. Modern Mud Logging could be more accu-xately termed "Drill Cuttings and Mud Gas Analysis". Presently, mud-logging has its greatest application in exploratory wells where subsurface geologic control is at a-minimum.

Jan 1, 1962