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By Paul C. Schmall, John F. Donohoe, Arthur B. Corwin, Derek Maishman

Ground freezing was utilized to provide complete stability of the excavation face and complete groundwater cut-off for the jacking of the three tunnel boxes for the Interstate 90 / Interstate 93 approach to the Fort Point Channel crossing. Through a wide range of geological conditions and large buried obstructions, the freezing provided complete stability of the face so that a 11.5 m (38 ft) high free standing vertical face could be mined without the need for any additional face support. Obstructions were incorporated into the massive frozen ground matrix, and held in place so that they could be excavated with a minimum of disturbance. The freezing provided an absolute groundwater cut-off, and permitted the work to be done without disturbance to the active rail system immediately above. With the use of instrumentation such as borehole thermocouples, the effectiveness of the freezing was guaranteed and the jacking proceeded with complete confidence and assurance of the ground conditions ahead.

Jan 1, 2001

By E. J. Bonet, P. B. Crawford

It is fairly common practice to reinject water into the aquifer near the oil-water interface in water-drive reservoirs. There have been many studies of aquifer behavior without reinjection,l-5 but apparently no analytical studies have been made to indicate performance when injection wells are present in the aquifer. The diffusivity equation may be used to describe the pressure behavior in an aquifer. When sources are present it can be written as A general solution of Eq. 1 may be obtained as the sum of two solutions. One is a general solution of the homogeneous equation, obtained by dropping the source term in Eq. 1 and still satisfying the required boundary conditions. Another is a general solution of Eq. 1 satisfying homogeneous boundary conditions.1° The first solution, which corresponds to the aquifer without reinjection, has been given quantitative and qualitative treatment in the literature.l-5,8,9 The latter solution will be treated here. Solutions with variable injection rates are obtained by superimposing solutions with constant rates, so we have considered only the latter. Five cases have been treated here: 1. A linear aquifer of finite width and extent. Water is injected into the aquifer at point xo, yo at constant rate. The pressure along the line x = 0 is maintained at zero pressure. (See Fig. 1.) Equations showing the pressure distribution, rates, velocity and cumulative influx have been developed. Certain numerical results are shown. 2. A linear aquifer of finite width and extent. Water is injected into the aquifer at point xo, yo at constant rate. The rate of production along the oil-water water contact is maintained constant. Equations showing the pressure distribution inside the aquifer are presented. 3. A linear aquifer of finite width and extent. Constant pressures are maintained at opposite ends of the aquifer. Water is injected at constant rates at point xo, yo. Equations showing the pressure distribution are shown. 4. A linear aquifer of finite width and infinite extent. The pressure is maintained constant at the oil-water contact. Water is injected at a constant rate at point xo, YO. 5. A linear aquifer of finite width and finite extent. The pressure at the oil-water contact is maintained constant. Water is injected at constant rate per unit length along a line x,. The Linear Aquifer The linear closed aquifer, performing at constant terminal pressure was selected as the first case to be analyzed. The development of the equations is based on uniform injection per unit of thickness, and gravity effects are neglected. In practical application this condition is probably most closely achieved when the

Jan 1, 1970

By Henry J. Walqui

En las centrales termoeléctricas alimentadas con carbón, las emisiones de gas están gobernadas por tres factores en los combustibles, donde el tamaño de particulas afecta directamente la temperatura de los gases e indirectamente el tiempo de residencia. En ese sentido, la capacidad de predecir y controlar el tamaño de particulas permitiría hacer ajustes en los paramentos operacionales de las calderas, de tal manera que las condiciones de combustión más eficientes sean alcanzadas. Por ello, el presente texto plantea el modelamiento matemático como herramienta que sirve para predecir la distribución de tamaño de partículas resultante del proceso de reducción de tamaño que se desarrolla en los pulverizadores de carbón a través de modelos de balance poblacional que puedan reflejar cambios en equipo, materiales y condiciones de operación.

Aug 25, 2002

By B. K. Gorain

"Mining of low grade deposits along with the necessity to design and operate process plants requiring high throughputs presents unique metallurgical environmental and sustainability challenges that need to be addressed to reduce project risks, improve project economics and to sustain the profitability of operations over the life-of-mine.Some of the key challenges include poor recovery of valuables and concentrate quality issues due to complex mineralogy and high ore variability, water scarcity and quality issues, high energy costs, complex environmental issues including tailings management, high capital and operating costs, worldwide constraints on resource availability, complicated regulations in emerging economies, changing demographics of mining operations with ever-changing cultural or community issues and the urgent need for a better assessment of project viability to reflect the dynamics of present mining scenario. Developing breakthrough solutions to these problems is the key to success of any new project and maintaining profitability of a mining operation. An integrated multi-disciplinary approach to problem solving is crucial along with the need for a more lateral thinking, strategic partnerships and collaboration involving the right players. This paper presents some of the key findings based on experiences from a large number of challenging projects and operations focused on solving complex metallurgical problems.IntroductionThere is a plethora of challenges in developing new ore bodies. The metallurgical complexity of these deposits has increased significantly due to the need for mining lower grade ores along with the presence of deleterious elements that have environmental and processing implications. In addition, many of the mining projects are capital intensive due to high throughput requirements to be economical along with the need for building infrastructure due to remote locations, while operating costs steadily increase due to high reagent, energy and labour costs, increased state royalties and community obligations, to name a few of the key factors. There is also scarcity of water in many regions requiring the use of sea water or brackish water, which has both environmental and metallurgical implications. The shortage of qualified technical manpower adds significantly to the woes of many mining companies. Considering these multiplicity of challenges, it has become imperative for many mining companies to be innovative in addressing these issues."

Jan 1, 2015

By Madgwick J. C, Ralph B. J

A method for the determination of microgram quantities of uranium in leachates from low grade uranium ores is described. Solubilized manium is purified by transfer to an organic solvent by a selective solvent extractionprocedure using tributyl phosphate, iso-octane, and aluminium nitrate. The organic phase is mixed with scintillation fiuors in toluene and the radioactive decay determined in a liquid scintillation counter. The method is sensitive and reproducible in the range 3-30 µg uranium.

Jan 1, 1978

Tellurium (Te) is one of the least abundant elements in the crust and tends to form minerals associated with copper, lead, zinc and iron sulfide deposits. Today, most tellurium production comes from the anode slimes and other wastes generated in metal refining. Most of the current tellurium produced in the world is used as an alloying agent in iron and steel, as catalysts, and in the chemical industry. However, future demand and production could increase because tellurium is increasingly used in solar panels and some electronic devices. Tellurium minerals are found in Au-Ag districts in New Mexico, but were not considered important exploration targets in the past. In New Mexico, tellurium is found associated with porphyry copper deposits in southwestern New Mexico and with Au-Ag veins in the Eureka, Sylvanite, Organ, Lordsburg, Steeple Rock, Wilcox, Mogollon, Chloride, Cuchillo, Hillsboro, Zuni Mountains, White Oaks, and Nogal-Bonito districts. The only tellurium production from New Mexico has been from the Lone Pine deposit (Wilcox district), where approximately 5 tons of tellurium ore was produced. Gold-tellurides are found with gold, silver, pyrite, and fluorite in fracture-filling veins in rhyolite at Lone Pine, with reported assays as much as 5,000 ppm Te. Other districts in New Mexico have potential for tellurium, but require field evaluation.

Feb 27, 2013

By Paul C. McWilliams

The U.S. Bureau of Mines has, primarily through its contract program, used large-scale centrifuges to determine design criteria for tailing embankments. The centrifuge runs were made at two installations, the University of Cambridge, Cambridge, England and Sandia National Laboratories, Albuquerque, NM. The major problems considered were as follows: slope stability of embankments, modeling erosion and seepage, use of the phreatic surface level to ascertain the validity of centrifuge modeling, and the effects of compaction and weathering on a tailings embankment. This report summarizes the results of the four test series conducted at University of Cambridge and Sandia National Laboratories. A review of prior centrifuge applications to mining problems is included. Consideration is given to future centrifuge application to mining problems in both soil and rock mechanics.

Jan 1, 1989

By Dana C. Reinke

Jan 1, 2005

By J. R. Thoenen

In the summer of 1937 the authors began a series of time studies of the various processes employed in' the production of crashed stone. These studies, made at quarries situated in the eastern and southeastern parts of the United States, have not been completed, but to make results available to the industry as early as possible, it was decided to publish summarizes of the studies made to January 1, 1939, as a series of progress reports. The first of these dealt with power-shovel loading and was issued as Report of Investigations 3461 in September 1939. The second, issued in September 1939 as Report of Investigations 3467, dealt with quarry haulage. The present report discusses analyses of time studies of primary drilling a t the same group of quarries. OBJECT OF STUDY Pressure of business problems frequently requires the entire attention of quarry management, and in consequence internal plant economies often are neglected. Also, operating officials absorbed in their local problems are prone to overlook possible economies that would attract attention immediately were they critically examining another plant. The authors felt that technical studies at a number of plants, made by impartial engineers, might disclose opportunities to reduce costs or improve efficiency in internal plant processes.

Jan 1, 1940

By B. Unver

Effective strata control is a prerequisite for maintaining an efficient mining operation. If the strata in the vicinity of an opening are not controlled effectively, it is impossible to perform a safe, efficient and economical operation. In this paper, the reasons and outcome of instability problems observed in roadways opened in clay and marl at the Bolu Colliery of Yeni Çeltek Establishment are investigated. Roadways under examination were located in a syncline causing high residual tectonic stresses. Factors affecting the instability have been studied thoroughly by examining geology and tectonics of the area, establishing convergence measuring stations to understand in situ behaviour of supports and laboratory tests to determine engineering properties of samples taken from nearby convergence measurement stations. As a conclusion, a new production strategy and a new support system are recommended to maintain stability.

Jan 1, 1999

By H. P. Jacobi

"The last 25 years have seen tremendous economic pressure placed upon the base metal processor. Industry has responded with technological innovations that have contributed to significant reductions in capital and operating costs. Major changes in processing machinery and philosophy are highlighted for the main unit operations of a base metal mill. Changes in our attitudes on what is environmentally acceptable are also discussed.INTRODUCTIONNewton's law of motion paraphrased states that nothing will change unless there is a pressure to do so.Aase metal processing as a primary commodity related industry has been under severe economic pressure over the last 25 years. This has been brought on by over capacity from new operations in the L.D.C. 's, through material substitution in a host of traditional base metal applications and generally reduced world-wide economic activity. In addition to shrinking markets our collective environmental consciousness has raised effluent standards and workplace hygiene and the employee's as well as government's economic expectations of how much ought to be derived from ''nature's riches''.Industry has responded with technological changes which, it was hoped, would counteract the cost squeeze in which it found itself.I would like to briefly enumerate the major changes, as I see them, that have taken place in the main unit operations that form the normal processing chain for base metals.While the following paper will mention several brands of products, I would like to emphasize that these are the ones that I am most familiar with and is not to say that they are the only manufacturers which have contributed to changes. In fact it ls fair to say that all makers of mining and processing equipment have made improvements to their products, to a greater or lesser degree; they have had to, to still he in business in 1986."

Jan 1, 1987

By P. Falcão Neves

A detailed analysis of the geomechanical behaviour in rock cutting with a diamond saw is provided to obtain a better understanding of the mechanisms involved in the process. The energy of elastic deformation (before failure) and plastic deformation (post failure) was determined in uniaxial compression tests as well as the energy consumed per unit volume in the cutting process. The test samples are White and Ruivina marbles from Borba - Vila Viçosa in Portugal. Correlations between total deformation specific energy and cutting specific energy, normal and tangential forces and diamond indentation are analysed, and some conclusions are presented.

Jan 1, 2012

By Francis X. Cannaday

Equipment and techniques were developed with Bureau of Mines facilities for measurement in the laboratory of sonic shear wave velocity in variously shaped rock specimens in a wide range of sizes. A variety of rock types was tested. The shear wave front is produced by electronically excited, piezo-electric ceramic) disk-shaped transducers. Transmitter and receiver are interchangeable. Special equipment components were Bureau produced; other components were commercially available. The equipment permits quick measurement of shear wave velocity on variously shaped specimens with a minimum of specimen preparation. The technique, under favorable conditions, allows for determination of the moment of arrival of the shear wave when it is superimposed on a weak longitudinal wave.

Jan 1, 1968

Pillars with width to height ratios of less than 1.0 are frequently created in underground hard rock mines. The strength of slender pillars can be estimated using empirically developed equations. However, the equations can provide variable results when the width-to-height ratios approach 0.5. This paper investigates some of the issues affecting pillar strength at low width-to-height ratios in hard brittle rock. The investigation includes an evaluation of empirical pillar strength data presented in the literature and observations of pillar performance in underground limestone mines in the eastern United States, supplemented by numerical modeling in which failure processes and sensitivity of slender pillars to variations in rock mass properties are evaluated. The results showed that the strength of slender pillars is more variable than that of wider pillars. The numerical model results demonstrated the increasing role of brittle rock failure in slender pillar strength. The absence of confinement in slender pillars can result in a fully brittle failure process, while wider pillars fail in a combined brittle and shearing mode. The onset of spalling in slender pillars occurs at or near the ultimate strength, while this is not the case for wider pillars. Slender pillars are shown to be more sensitive to the presence of discontinuities than wider pillars, which can partly explain the increased variability of slender pillar strength. Two examples are presented, which illustrate failure initiation by brittle spalling and the sensitivity of slender pillars to the presence of discontinuities.

Jan 1, 2006

By Sanjay Kumar Singh

The mechanics of load transfer in bord-and-pillar mining is not well understood despite the evolution of the art of pillar extraction over the last 20 years via trial and error (empirical) or Rock Mass Rating (RMR), simple monitoring and pillar extraction experiences at neighboring mines. Variations in geologic conditions and pillar extraction methods, along with a lack of comprehensive instrumentation programs for monitoring ground behavior during pillar recovery, are among the factors that make it difficult to predict how strata will respond to pillar extraction. Efficient and safe use of roof supports depends on the interaction between the designed support and coal strata. Of particular interest in this study is the mechanics of strata deformation as influenced by geologic conditions, pillar extraction methods and optimum support with load-bearing capabilities in strata control during mass exploitation of underground coal deposits required detailed investigation,?. To provide a better understanding of the mechanics of strata deformation, as researchers, we have collected data and reviewed measurements of convergence and stress in one mine of South Eastern Coalfields Limited (S.E.C.L.), i. e., in North Chirimiri Pondary Hills (NCPH) and have completed numerical modeling with FLAC software for (Fast Lagrangian Analysis of Continua modeling, Itasca India Consulting Pvt. Ltd.) for two typical pillar extraction plans. Stress distribution in the mine roof above pairs of roof supports was calculated to demonstrate how Resin roof bolt support installed support contributed to roof block movement control. It was shown that overall stress and roof-floor convergence patterns were most influenced by the stiffness of coal measure rocks and by pillar extraction sequences and layouts. Also, resin roof bolts and other support systems play a critical role in controlling stability of both the immediate roof and the main roof for a distance of up to 18 meters (i.e., working coal seam height X three times) above the seam. Installed supports provide unique strata control advantages over other types of secondary support by significantly reducing the time between mining and installation of the secondary support. Although resin roof bolts are similar to posts in stiffness and capacity, they are more effective than posts under static loads because they can yield and still maintain loads at nearpeak capacity(Singh, et al., 2006), whereas posts fail and lose their ability to limit mine roof deformation.

Jan 1, 2012

By P Lever, D Hainsworth, H Gurgenci

The ACARP Landmark initiative has created the opportunity to advance the level of automation in the coal industry by first focusing on the core production area of longwall mining. A Landmark Longwall Automation project was commenced in July 2001. The major outcome of automation using on-face observation has been divided into ten outcome areas that have been fully scoped for a three-year initial project life. A major facilitating technology has been the implementation inertial navigation system (INS) technology that can map the shearer position in 3D. A focus of the project is to deliver a system that is at least as productive as the current most productive manually controlled longwall face.

Jan 1, 2002

By Gil Ribeiro Vilela Neto

Na busca por se tornar cada vez mais sustentável, a indústria mineral vem recorrendo às soluções tecnológicas que minimizem o impacto ambiental gerado pela disposição dos rejeitos resultantes dos processos de beneficiamento de minérios. Neste cenário, umas das soluções é a aplicação de tecnologias de separação sólido-líquido com o objetivo de maximizar o desaguamento dos rejeitos e, consequentemente, diminuir o volume ocupado por eles quando dispostos e aumentar a recirculação de água. Este trabalho tem como objetivo, determinar a influência da concentração de sólidos em polpas de rejeitos denominados de “lamas” no desempenho do espessamento e a determinação da concentração de sólidos ótima para atingir o melhor desempenho do espessador.

Aug 16, 2017

By José Eustáquio da Silva

Este trabalho mostra a versatilidade e praticidade do uso da metodologia denominada “Método e Aparelho para Avaliar as Propriedades de Coqueificação do Carvão”, metodologia esta desenvolvida e patenteada pelo corpo técnico da SunCoke Energy. Esta técnica tem possibilitado o desenvolvimento de novas misturas de carvões totalmente alinhadas com os dois grandes pilares da Siderurgia mundial: misturas e coque com baixo custo e qualidade adequada. A fidelização com todas as particularidades do processo real de coqueificação faz desta metodologia uma poderosa ferramenta para tomada de decisão na definição de novos blends, como também para a caracterização de carvões dos quais ainda não se conhece seu potencial para produzir um coque de boa qualidade. Diferentemente das tecnologias similares existentes, o “Box Test” da SunCoke Energy tem robustez suficiente para ser reutilizado para até quatro enfornamentos e é capaz de produzir massa suficiente de coque para que sejam realizadas todas as análises para uma perfeita caracterização do coque.

Aug 17, 2017

By Alvin Kaufman

To aid industry and Government in planning water developments the Bureau of Mines in 1963 canvassed mineral producers to determine water use in 1962. Water use by the mineral industry comprises only 2 percent of the water withdrawn by industry as a whole. The major water-using mineral industries are natural gas processing, phosphate rock, sand and gravel, and iron ore. Analysis indicated the following conclusions: 1. Total water use and new water intake is dependent on the quantity of material processed and the process water requirements of the particular industry or commodity. 2. Recirculation is dependent on the processing requirements of a particular commodity, the manner in which the water is used, cooling and condensing requirements in certain large industries, the quality of new water intake, and the need to treat new and discharged water. 3. Consumed water is dependent on the quantity of water recirculated, the temperature and humidity in the area, and the proportion of water used for cooling and condensing. 4. A threefold increase in water use by the mineral industry by 1985 is forecast.

Jan 1, 1966

By T Wootton

The Barrytown ilmenite pilot plant was commissioned in two stages using Westport Titanium Project heavy mineral concentrate. The wet concentrator was commissioned on the 17 December 1989 and produced magnetic concentrate from this date.   The Drymill was commissioned on the 27 January 1990 and produced product grade ilmenite successfully from the onset.   The commissioning period was exceptionally short by normal standards and few problems were encountered. This paper concludes with general observations of operations of the pilot plant.

Jan 1, 1990