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By Erik Málaga

En la actualidad el precio de los metales en especial el cobre es una variable exógena, que no podemos controlar, esta situación nos obliga a repensar el tema económico y fijar el costo con un punto de equilibrio lo más óptimo posible, que nos permita subsistir y evitar medidas traumáticas de reducción, ya que los impactos difieren cuando corporaciones mineras de la competencia presentan costos de operación más bajos, con puntos de equilibrio de mayor holgura y manejo producto de la aplicación de un “Sistema de Gestión Exitoso” implementado en el transcurso de su vida minera.

Sep 29, 2023

By T. P. Chidakwa, T. R. Stacey

This study investigated the corrosion rates of various steel types and coatings used for friction rock stabilisers in a deep-level gold mine under diverse underground environmental conditions. Testing was conducted in situ within ramps, intake airways, and exhaust airways, and through simulated laboratory experiments. Results revealed that environmental variations significantly influence the corrosion performance of different materials and coatings. Duplex coatings, made up of galvanised steel with an organic paint layer, demonstrated the highest corrosion resistance. Zinc-based coatings provided moderate protection, while 3CR12 stainless steel and uncoated S420 carbon steel exhibited comparatively poor resistance under both aqueous and atmospheric conditions.

Mar 4, 2025

By R. F. Waters

Laboratory-scale selective volatilization methods developed by the Bureau of Mines to recover germanium and gallium concentrates from coal fly ash and phosphorus furnace flue dust are summarized. In the better experiments between 85 and 98 percent of the germanium was recovered as the lower oxide and as sulfides, and between 75 and 97 percent of the gallium was recovered as the lower oxide and as the trichloride. Grades of the condensates were inconsistent and varied between a few tenths of a percent and 8 percent, depending on the method used. In the primary extractions of germanium alone the degree of enrichment surpassed 100 to 1, and for gallium the best ratio was 30 to 1. Upgrading of condensates by vaporization retreatment and by leaching and precipitation is discussed. An appreciable degree of mechanical preconcentration by attrition scrubbing and elutriation was possible on two fly ash samples.

Jan 1, 1967

By D. E. Shanks

This U.S. Bureau of Mines (USBM) research simplified an earlier hydrogen chloride (HCI) leach-sparge process developed by the USBM to recover reduction-grade alumina from domestic kaolin clay. Improvements were made by decreasing the initial leaching acid concentration from 25 to 20 pet, decreasing the leaching time from 1 to 2 h to 15 to 30 min, eliminating the solvent extraction step for Fe removal, and eliminating the step to recover the AI content of the bleedstream circuit. A 10-cycle bench-scale experiment of the simplified process showed that the ferric chloride (FeC13) concentration built up to 9.3 g/L in the recycle stream. This did not interfere with any of the unit operations or final alumina product purity because Fe forms stable soluble chloride complexes when sparged with HCI and is easily washed from the large aluminum chloride hexahydrate (ACH) crystals. The reduced leaching time and acid concentration did not decrease Al extraction.

Jan 1, 2010

By Y. He

The nature of the density distribution in a gas-solid phase fluidized bed for dry coal separation is an important factor in influencing the performance. However, during coal processing, fine slime would mix with dense medium of magnetite powder and accumulate in the bed, and its influence will affect the density of the bed. The mathematical model of the density distribution with fine slime behaviour was studied in an experimental laboratory system. The functional relationship between the density of the air dense medium fluidized bed and the coal slime content were fitted, applying the principle of least-squares method with damping factors. With the model, by analysing the trial testing data, the mechanism of the density distribution of the bed was studied and applied to a coal separation test with a pilot scale separator. Keywords: dry coal separation, gas-solid phase, model fitting.

Jan 1, 2002

By Fernando Rodríguez

El artículo busca responder a esta interrogante: ¿cómo hacer para reactivar la minería y, a la vez, elevar nuestras prácticas de responsabilidad en el marco de los Objetivos de Desarrollo Sostenible (ODS) de las Naciones Unidas al 2030? El escenario de “nueva normalidad” post pandemia COVID-19 implica, para el sector de la gran minería, implementar formas innovadoras de explorar, diseñar, construir, operar y cerrar minas. Si bien el desafío es grande, esta situación constituye una oportunidad única para liderar la reactivación económica del país, de la mano de prácticas de responsabilidad social y ambiental ejemplares, que apunten a una mayor contribución al desarrollo sostenible.

Jun 30, 2020

By P. R. Jones

A computer program was written for design and cost of a shell and tube heat exchanger in which the total cost, which includes annual fixed charges and annual operating costs, was minimized. The program was written for the type of heat exchanger in which only the tube side pumping costs were significant and for triangular pitch, single or multiple pass, heating or cooling, and no change in phase. Tube diameter was not optimized since the tube dimensions do not affect the cost very much. However, the tube dimensions do affect the shell diameter, number of tubes, and length of tubes; and price optimum design was obtained for four standard tube diameters. Standard heat exchangers having at least the required area are also listed. The program was made adaptable to various fluids and to various tube dimensions by including many of the required data such as physical properties of the fluids, tube data, and standard shell data as input data.

Jan 1, 1969

By A. B. Parsons

DOWN in Washington an army of individuals constituting the government of a so-called "'democratic" nation is trying to manage the conduct, in its rnultifold phases, of the greatest war in history for the country that is potentially, at least, the strongest in the world and on which, consequently, the major responsibility rests. The enterprise is one of unprecedented magnitude and complexity. That individuals and groups have made and are making serious blunders, both as to the establishment and execution of policy, is to be expected.

Jan 1, 1942

By Melânea Almeida Ramalho Medeiros

A liga de níquel 718 encontra aplicações variadas nas indústrias aeronáutica, aeroespacial, óleo e gás e nuclear em função da excelente combinação entre resistência e ductilidade. As diferentes formas de processamento utilizadas para sua elaboração tendem a unir processos de deformação com temperatura, a fim de melhorar as propriedades mecânicas do material. Sendo assim, o presente trabalho tem como objetivo a caracterização e investigação do efeito de rotas de processamento termomecânicos distintas, avaliando a repercussão na fração de contornos especiais, dos carbetos (Nb,Ti)C e nas propriedades mecânicas do material endurecido por precipitação.

Aug 17, 2017

By Maurice E. Peloubet

This discussion of accounting will describe the statements and the information that the accounting system produces, from the point of view of those who use such systems rather than of those who prepare them and who do the detail and technical accounting work. In any well organized mine, quarry, or other enterprise exploiting a mineral deposit, no matter how small, some clerical and accounting work must be done. Miners and other employes must be paid, supplies must be purchased and issued, and various tax and information returns, which even the smallest enterprise must file, have to be prepared. In this chapter it is assumed that the enterprise has employes of this type and that they understand the fundamentals of record keeping and accounting. It would be impossible here to give sufficiently full explanations to enable a man with no previous clerical and accounting training to set up and operate an accounting and cost system for even the simplest extractive operation. Rather, we shall hope first, to tell the investor and the operator, from the chief engineer or president down to a subforeman, what to expect from the accounting statements and records and how to use this information in his daily work; and second, that it will enable the man with some knowledge of accounting or book- keeping, but with little or no experience in any extractive industry, to set up and operate a satisfactory system for a mine or other extractive enterprise. For readers who wish to go further, the bibliography at the end of this chapter contains many references. T he emphasis has, therefore, been placed on the statements to be produced and the purposes for which they are to be used rather than the underlying books and records. These are, with a few exceptions which will be described later, essentially what might be found in any industrial enterprise and would probably, in the extremely small enterprise, consist of handwritten journals, ledgers, analysis books, payroll books, and stores ledgers. In the larger enterprise, various types of mechanical accounting would be introduced in proportion to the complexity of the operation.

Jan 1, 1964

By Joshua Calnan, Braden Lusk, Kyle Perry

This paper presents detailed information and data regarding the load transfer characteristics of Blast Resistant Glazing Systems utilizing two different thicknesses of polycarbonate. A series of triaxial load cells, along with surrogates of identical stiffness characteristics, were placed around the glazing perimeter to directly measure the load transferred to the support system from explosions of varying degrees. The blast loads were developed using an explosive driven shock tube administered by the University of Kentucky Explosives Research Team (UKERT) in Georgetown, KY. Results presented include distribution of loading, maximum load transferred to connections, blast pressure-time data, glazing system deflection-time data, and final performance results of each system. The two glazing systems respond differently to the applied blast loading. Differences and similarities in the load transfer characteristics are discussed. The experimental results are then compared to a commonly used blast resistant glazing system analysis software tool utilizing a Single Degree of Freedom (SDOF) method of analysis for each system. Preliminary results show that currently used models do not correspond well with experimental data.

Jan 1, 2014

By E. P. Youngman

Before the World War the use of zirconium and its compounds was largely experimental and confined almost wholly to Germany and Austria . Occasionally small lots of zirconium ore had been produced in the United States ( 1,000 pounds in 1869 , 26 tons in 1883 , and 3,000 pounds in 1903 ) and used (with monazite ) in the manufacture of various lighting devices , especially incandescent gas mantles ; but it was not until 1906 that the discovery of the natural zirconium oxide in large quantities near Sao Paulo , Brazil , first gave promise that a zirconium industry eventually might be developed . Edward Rietz , who worked the Brazilian deposits , interested German chemists in extending the use of zirconium , and by 1911 trade journals were listing German firms as manufacturers of compounds or products derived therefrom . For a time zirconia was one of the various oxides used in the Nernst lamp . It was used also for crucibles and hearths as refractory material ; in the manufacture of chemical utensils ; in enamels ; in the place of bismuth subnitrate for defining Röntgenray pictures of the stomach ; as a pigment ; in medicine ; and in a number of other ways . The Germans were credited also with producing a remarkable zirconium steel , which , it was claimed , was much superior to other alloy steels . During the World War the United States Government investigated the possibilities of zirconium , as well as those of other steel -hardening elements , and a large automobile manufacturer actually purchased a substantial quantity of ore with the purpose of employing zirconium in automobile steels . Immediately after the armistice the Government ceased its investigations ; but despite the difficulties experienced by various investigators in reaching concordant results , interest in the use of zirconium as a steel -hardening agent , as well as in other uses of the element and its compounds , continued . In 1918 the Foote Mineral Co. , which had been interested in zirconium for several years , was exploiting the deposit in Brazil formerly worked by the Germans and was supplying zirconia in the form of ore , brick , and cement for refractory and other purposes . About the same time the Electro Metallurgical Co. , which before the entrance of the United States into the war was experimenting with zirconium alloys , supplied in tonnage quantities the demand for these alloys . In 1919 it was reported that American manufacturers , after several years of research, were producing in commercial quantities pure zirconium oxide , which was finding a place in the manufacture of small refractory articles , scorifying dishes , crucibles , tubes , and one- piece furnace linings . In 1920 the lowering of the price of zirconium metal powder ( because of improved metallurgical methods ) promised the production of the metal on a semicommercial scale . In 1924 the Titanium Alloy Manufacturing Co. introduced a new opacifying agent , " Opax , " made from zircon . A year or two later some of the large pottery manufacturers became interested in the use of zirconium oxide as an opacifying agent , the increased production of titanium pigments having resulted in the production of zirconium as a by-product at a price that could compete with tin oxide . In 1928 it was reported that the industrial use of zirconium oxide was increasing steadily in the manufacture of brick , crucibles , and other refractory products , such as high- temperature cements . However , the reluctance of producers to install additional and more suitable

Jun 1, 1931

By Frank L. Hess

In 1876 cassiterite was identified in the placer gold from the northern Black Hills, and such a mixture could have come only from Nigger Hill or one of the streams draining the hill, because in no other hart of the northern hills have cassiterite anti gold been found together. Nigger Hill is in western Lawrence County, South Dakota, and on it is the little camp of Tinton. The Wyoming line runs along the west side of the hill and crosses the ridge which is the hill's continuation about miles north-northwest of Tinton.

Jan 1, 1938

By W. J. Heck

The need for a better understanding of the effect of fluid pressure on the strength of intact and jointed rock has long been recognized. The behavior of pore fluid pressure was first pointed out by Terzaghi 1 who suggested the application of the effective stress concept to rock and concrete. While the effective stress concept has been used for some time in the design of mass concrete dams, it only recently has been applied to rock. Robinson 2 and Handin et al.3 evaluated the effects of pore pressure on a variety of sedimentary rocks and demonstrated the validity of the concept. Work using pore fluids other than water has been done by Boozer, et al.4 who considered strain rate and temperature as additional variables. According to the effective stress theory, the effective stress, [a], is the difference between the total stress, [a], and the pore pressure, u, and is the controlling factor influencing frictional strength of rock, other parameters remaining constant. Assuming the Mohr-Coulomb failure criteria applies, the shear strength, T, is given by the equation [r=d+ (a-u)tan ¢](1) where [~F], the angle of internal friction, and c, the cohesion intercept of "no load" shear strength, are the effective stress parameters.* Robinson,2 Handin,3 and others have demonstrated that moderately porous sand-

Jan 1, 1972

By The Mill Staff

"IntroductionCOMMENCEMENT of operations at the new No. 7 shaft and 10,000-ton mill at Creighton mine was a major step in the programme of conversion to all-underground mining by the International Nickel Company of Canada, Limited. Planned ten years ago, the orderly transition has been greatly speeded-up to offset the heavy drain on production imposed by World War II and also to meet the increased demand for nickel caused by the current international situation. Development of new mining methods, and process changes in the reduction plants, have made possible the economic recovery and utilization of ore of lower grade than formerly used and of varying metallurgical characteristics. By 1953, when the Company's open-pit mining operations are scheduled for completion, the hoisting capacity of its five underground mines in the Sudbury district will have been increased to 13,000,000 tons per year, compared with 5,700,000 tons of underground ore hoisted in 1950.Two types of ore occur at Creighton. One is a breccia and stringer type that contains a high percent-age of massive sulphides and is located in sheets along shears and in large and small pockets on the underside of the main norite mass; the other type, forming the main part of the ore zone, is mineralized norite that occurs as a •sheet up to 400 feet thick overlying tl1e breccia ore. In both types of ore the minerals of economic interest are pentlandite, which is intimately associated with pyrrhotite, and chalcopyrite. Early mining was confined to the breccia ore; this ore was mined by open stoping methods. The hanging-wall was later allowed to cave, with the result that the old stopes are now filled with caved low-grade ore."

Jan 1, 1952

By Jeann Diniz Ferreira Lima

Este estudo avaliou a influência da adição de um composto inorgânico radiopacificador sobre as propriedades do cimento Portland Branco, a fim de viabilizar sua utilização como cimento endodôntico, semelhante ao MTA. Primeiramente, cimento Portland Branco foi caracterizado por difração de raios-X, os resultados mostram que a amostra possui composição semelhante ao MTA, com exceção de bismuto na composição do material. O bismuto, segundo a literatura, é o agente radiopacificador presente no cimento endodôntico na base de MTA. Posteriormente foi selecionado um composto inorgânico, devido seu potencial radiopacificador para continuação do estudo, sendo este o Carbonato de Bismuto (Bi2(CO3)). Neste estudo foram avaliadas as seguintes propriedades; Tempo de presa inicial, compressão dimensional, solubilidade e alteração diametral, sendo todos os ensaios seguindo de acordo com a norma ISO 6878:2001. Para a realização destes ensaios, foram utilizadas amostras contendo 15% de Carbonato de Bismuto em sua composição. Comparando os resultados obtidos neste estudo, foi verificado de acordo com a literatura, que cimento Portland Branco acrescido de 15% de Carbonato de Bismuto possui propriedades semelhantes às do MTA, sugerindo assim, a viabilidade de sua utilização como alternativa menos onerosa aos demais materiais comercializados.

Aug 16, 2017

By Frank L. Hess

In 1876 cassiterite was identified in the placer gold from the northern Black Hills, and such a mixture could have come only from Nigger Hill or one of the streams draining the hill, because in no other part of the northern hills have cassiterite and gold been found together. Nigger Hill is in western Lawrence County, South Dakota, and on it is the little camp of Tinton. The Wyoming line runs along the west side of the hill and crosses the ridge which is the hill's continuation about miles north-northwest of Tinton.

Jan 1, 1938

By Luis Vargas B Barbieri

El presente texto señala las posibilidades a futuro de incrementar la producción cuprífera del Perú. Los dos países desarrollados con grandes reservas de cobre son Estados Unidos y Canadá y estos no tienen yacimientos interesantes, ya que los mismos o tienen leyes muy bajas o sus reservas no son comparables a los prospectos mineros del Perú, Chile, Panamá, etc. De otro lado, se clasifica las reservas con el precio del cobre. Los precios se determinan de acuerdo a la información de las memorias anuales de las empresas propietarjas; así como las declaraciones de los funcionarios de las empresas y de las autoridades gubernamentales en el caso de los países en desarrollo.

Jan 1, 1980

By J. K. Whyatt

The U.S. Bureau of Mines conducted an overcore stress measurement on the 5300 level of the Lucky Friday Mine, Mullan, ID, to investigate the stress regime around an experimental stope in a rock-burst-prone mine. The result indicated a stress field with unexpected magnitude and orientation [s 1 ?135 MPa (19,600 psi) oriented S 80° W). An unusual amount of rock-burst activity was encountered during subsequent excavation. A careful review of the overcore data suggested the overcore strain measurements were valid. Moreover, concentrated rock-burst activity suggested that the measured stress field did exist, but was localized and therefore did not represent the far-field in situ stress field.

Jan 1, 2010

By Arthur Grounds

Historical In the course of a paper which is necessarily limited in length, such as the present one, it is obviously impossible to describe in detail the history, development, and present position of coal preparation in Western Europe. Great Britain has been blessed with large deposits of excellent coal of nearly every type, ranging from the high-grade anthracites of South Wales, which are characterised by their very low ash and volatile con-tents, to the superb coking coals of South Wales and Durham -probably the finest in the world -with their low ash and sulphur contents, the latter constituent often well be-low l per cent. Gas coals abound in Lancashire and Yorkshire, while coals from the East Midlands, Northumberland, and Scotland are excellent for steam-raising and other industrial purposes. The excellent quality of these various coals has, in years gone by, ensured ready .sales abroad and it is not surprising, therefore; that methods of coal preparation were largely developed on the Continent in an endeavour to upgrade the inferior fuels found there, so that the prepared product could compete with British coals on the European market.

Jan 1, 1951