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By W. C. Smith

Even with conservative mine planning, rib instability can progress from a nuisance to a major safety hazard. This Bureau of Mines paper examines the mechanisms of progressive rib failure in high mine openings and discusses techniques to control rib slabbing. A field test site in a longwall mine was instrumented to investigate rib behavior during mining. While data analysis showed minor pillar dilation. sporadic zones of progressive rib instability were detected that culminated in eventual rib failure. The failure occurred despite conservative pillar dimensions and shallow depth. Models were used to demonstrate the mechanisms of rib failure and then evaluate the influence of support and other mine-related parameters on rib behavior.

Jan 1, 1991

By William Gleason

"The city of Denver, CO has experienced extreme growth in the past decade, with the population of the city topping more than 700,000 people in 2018. The current storm water drainage system was put in place in the early 1900s and has not been able to keep up with the growth of the city.When it rains north and east of the city, the runoff goes toward the South Platte River. With the dense population and sometimes severe thunderstorms in the summer, the city has experienced significant flooding that not only endangers lives of residents, but some of the storms have caused millions of dollars of property damage.The Platte to Park Hill Project is a $298-million nearterm, four-phase solution to the flooding that includes the Globeville landing outfall; an open drainage project in the Cole neighborhood in north Denver; an area for temporary water detention and another temporary water detention in Park Hill.The largest and most complex phase of the project is the Globeville landing outfall — a $70-million box culvert project that includes a pair of 157-m (515-ft) long, 243-cm (96-in.) diameter storm water tunnels that pass beneath a busy rail yard with 17 tracks for the Union Pacific Railroad (UPRR) and two Regional Transportation District (RTD) commuter rail tracks. The tunnels, which were installed parallel to a pair of existing 243-cm (96-in.) tunnels, were designed by Brierley & Associates as a client of Merrick & Company for the City & County of Denver, and Bradshaw Construction constructed the one-pass tunnels.From the start, it was evident that the tunneling portion of the project would be the most challenging because of the rail yards.“It’s a little bit more complicated because the railroads have such tight restrictions for settlement,” said Rebecca Brock, Brierley’s project manager. “We had a lot of meetings with Union Pacific and RTD to figure out what are prescribed versus tolerable settlements.”“The portion extending beyond the UPRR under the RTD rails was challenging, as RTD is new to tunnel installations under its tracks,” said Lester Bradshaw, president of Bradshaw Construction. “The RTD tracks employed a unique foundation of continuous concrete with integral raised concrete ties on rubber bushings. Minimizing settlement to these tracks was a critical requirement.”"

Jan 9, 2018

By J. D. Miller

Fluid flow phenomena and therefore the flotation efficiency of air-sparged hydrocyclone (ASH) flotation are strongly dependent on the operating and design variables such as air flow rate, slurry flow rate, underflow and overflow opening areas, percent solids in the feed, reagent levels, particle size, ASH length, etc. Time-averaged multiphase flow characteristics, as deter-mined by x-ray CT and described in a previous publication, are used to understand and explain the steady-state ASH flotation of quartz. A detailed parametric study of quartz flotation by a nominal 2-inch diameter air-sparged hydrocyclone (ASH-2C) revealed the influence of these variables on the flotation response which is discussed in terms of the multiphase flow characteristics. Thus, a phenomenological description of quartz flotation has been established to assist in the further development and utilization of the ASH technology.

Jan 1, 1995

By Albert J. Kritscher

The Similkameen Copper Project located near Princeton, British Columbia, is operated by the Similkameen Mining Company Limited, a wholly-owned subsidiary of Newmont Mining Company. The orebodies for this project are located on both sides of the Similkameen River for which the project is named. The project involves the processing of an average of 15,000 STPD of andesitic ore, mineralized largely with Chalcopyrite, at an overall plant availability rating of 90 percent. Project life is nominally 15 years. Design for the plant and its ancillary facilities was undertaken by Bechtel Corporation with procurement and construction management by Canadian Bechtel Limited. Construction began in June 1970 and first ore was introduced into process in March 1972. This paper concerns itself only with the project tailing system. The processing plant is located on a bench of glacial stream gravels which overlooks the river canyon. This site represented the only relatively flat area of sufficient size to accomodate processing facilities near to the ore- bodies. Reference is made to Figs. 1 and 2 showing the relationship of project features in plan and profile.

Jan 1, 1973

By F. G. Miller

It is generally accepted that sulfur exists in coal in three forms: (1) pyritic, (2) organic, and (3) sulfate sulfur. Sulfate sulfur usually makes up less than 1% of the total sulfur content. Pyritic and organic sulfur, make up almost all of the total sulfur and occur in varying amounts in different coals and can vary greatly in coal of the same seam Pyritic sulfurs of 20% to 80% of the total sulfur have been reported Other authors have shown that it is not possible to remove the organic sulfur without chemically altering the coal. Chapman and Jones (1) state: "Organic sulfur, unlike pyritic sulfur does not exist as discrete particles, but is intimately associated with the coal structure, and as such it is not possible to remove it or reduce its concentration by physical means." Any success in removing sulfur has come about by removing pyritic sulfur by physical means; therefore, removal of sulfur in the pyritic form is the subject of this investigation. The extent to which any impurities can be removed from a particular coal can be determined by a washability study. Outside of crushing coal, to finer sizes or chemically altering the coal, there are no known methods of changing this inherent washability characteristic. The efficiency of various methods used to remove impurities can be determined by comparison of results produced at a yield to the results as shown by a washability study. In recent years heavy media processes have proven their ability to wash plus 28 mesh coal and nearly produce results shown to be theoretically possible by the washability study. Therefore, it is the objective of this paper to show various methods of treating the finer fractions of the coal, in the hope of developing a process, which can effectively produce in the fine fractions the efficiency of heavy media devices in the coarse.

Jan 1, 1963

By B. A. Massey

Sooner or later, we'll encounter a subordinate, peer, or boss that will test our management skills to the limit. The chances are good that our formal educations have not fully prepared us to effectively handle the situation, and through trial-by-fire, we have learned that the management of people is often as much an art as it is a science. Assertiveness - as opposed to agressiveness - is basically positive persuation. Assertive management techniques can help combine the art and science of managment to sell ideas, accomplish goals, direct the workforce, and generally promote the corporate - as well as our own - objectives

Jan 1, 1986

By William Gleason

"When Dr. Joseph A. Holmes was named the first director of the U.S. Bureau of Mines in 1910, the challenge in front of the mining industry was urgent and profound. Just three years before the Bureau was formed, the United States’ coal industry saw a spike in fatalities, as 3,242 miners lost their lives, including 918 miners killed in 18 major disasters. Holmes, who is often called the Founding Father of Mine Safety, was charged with researching and finding new and safer methods to conduct mining activities as well as more efficient ways to conduct mine rescue to educate miners.The U.S. Bureau of Mines was dissolved in 1996, but the mission of the Holmes Mine Rescue Association remains intact, although the challenges have changed greatly.During the 102 years between its formation and the 2018 Joseph A. Holmes Safety Association & Holmes Mine Rescue Association Annual Meeting and Training Seminar in Denver, CO June 5-7, the mining industry has evolved to become one the safest industries in the United States, with an injury rate on par with school teachers and better than retail workers. The work of Holmes and the Bureau of Mines plotted a course for others to follow, and the fatality rate has plummeted to historic lows. However, those who work in the mining safety and health sector remain diligent to their cause and are slow to celebrate too much the accomplishments of the past century, focusing instead on the work that lies ahead.“The nature of mining accidents has changed and it is very difficult to make changes when you get down to the asymptotic part of the equation,” David Zatezalo, assistant secretary of the U.S. Mine Safety and Health Administration (MSHA) told Mining Engineering. He was the featured speaker at the Joseph A. Holmes Safety Association annual meeting’s banquet dinner and presented a thorough overview of the mission of MSHA and his goals as its top man.Nominated by President Donald Trump, Zatezalo was sworn in as the ninth assistant secretary for MSHA on Nov. 30, 2017 and brings with him a lifetime of experience in mining. During his presentation, he displayed the chart (Fig. 1) showing the dramatic improvement in safety that the industry has achieved during the past century, but he noted that, as the industry gets closer to its end goal of zero fatalities, it has become increasingly more difficult to cross the finish line."

Jan 8, 2018

By J. A. Herbst

Until the past decade, the energy-size reduction relationship was the dominant form of mathematical model used in the description of tumbling mill grinding processes (1,2). Typically, in these models some single measure of product fineness (e.g. the 80% passing size, the size modules, the specific surface area) is chosen as the dependent variable and the energy input per unit mass of material being ground acts as the independent variable. In some instances these models have been useful for the correlation of experimental data, but, invariably, they have been found to be inadequate for meaningful process simulation. During the last decade considerable advances have been made in the development of phenomenological grinding models derived from population balance considerations (3-7). In these models a set of dependent variables is employed, corresponding to the set of mass fractions which constitute the product size distribution, and energy input is abandoned in favor of "time in the mill" as the independent variable. The phenomenological models have been shown to provide accurate simulations of the entire size distribution of ground products produced in batch (8-10), locked cycle(11)and steady and unsteady state, open and closed circuit continuous grinding(12,13).

Jan 1, 1973

By Thomas D. Henderson

Este capítulo presenta- un "caso histórico" de los pasos a dar para estimar IDS castes de capital y operativos para un concentrador típico de cobre porfirico de ± 9;070 toneladas métricas de producción diaria. El concentrador que se describe es hipotético, pero está basado en la experiencia propia y es, en efecto, una composición de varios proyectos reales. Las cifras utilizadas son ilustrativas solamente y no representan los castes reales de ningún lavadero en particular. Estas cifras son, sin embargo, representativas de los castes tipicos de molienda en un punto en el tiempo y son to suficientemente precisas coma para iIustrar los procedimientos de estimación de castes descriIos en este capítulo, No es posible publicar cifras reales y corrientes de los castes del lavadero y, en cualquier caso, las cifras de Ios castes reales pierden rápidamente su significación en Ia actual situación económica con los rápidos incrementos de las diversas partidas que configuran los castes. El trabajo está dividido en tres partes: (1) orden de la magnitud estimada, (2) estimación def estudio de viabilidad, y (3) comparación entre los castes estimados y los castes rea¬les. Con vistas a este trabajo supondremas que una mina tiene una propiedad minera explorada mediante perforación con testigos que refleja un yacimiento, ampliamente definido, como de unas 45,3 millones de toneladas métricas con una ley del d,6°/ de sulfuro de cobre, Esta compañia desea obtener primero una estimación del orden de magnitud de los costes (canto de los costes operativos como del capital) para determinar si la pertenencia garantiza más perforación y desmuestre de testigos. Suponiendo que esta evaluación económica obtenida utiIizando Ia orden de Ia magnitud de Ios costes sea favorable, sera a continuación requerido un estudio de viabilidad más preciso de los castes de capital y operativos. Seguidamente of recemas una descripción de los diferentes pasos dadospara desarrollar ]as costes del orden de primera magnitud y a continuación para los castes del estudio de viabilidad.

Jan 1, 1982

By Joseph E. Worthington

The Haile Gold Mine is one of the earliest gold discoveries in the eastern United States as well as one of the largest gold producers from that region. Gold was first discovered in the gravels of what is now known as Haile Gold Mine Branch in 1828 on lands then owned by Colonel Benjamin Hale (spelling not the same). Small placer workings were immediately started and it was not long before the surrounding residual soils and saprolites were also found to contain gold. Following the presence of gold in the residuum eventually lead to the discovery of the underlying gold-bearing lodes that actually outcropped in saprolite form where not masked by heavy vegetation or a thin veneer of Coastal Plain sand. The earliest attempts at production, immediately after discovery, utilized slave labor, washing gravel and residuum from leased tracts that were 15m (50 ft) square. Several at- tempts at small milling operations were made during the en- suing decades, but there was really no substantial or successful production until the 1880s.

Jan 1, 1990

By S. E. Phillipson, S. Romberger

The Late Miocene San Cristobal Ag-Zn-Pb deposit represents syngenetic and epigenetic mineralization with low- and high-sulfidation characteristics. The geology of the deposit is characterized by barren dacitic ring fracture domes, mineralized resurgent rhyodacite domes, strongly altered and mineralized tuffaceous lacustrine sedimentary rocks and an extensive crystal-lithic tuff debris apron. The orebody is hosted by intracauldron sedimentary rocks and breccias. Fluid inclusion data suggest that silver, lead and zinc were transported as chloride complexes and precipitated by cooling in veins from <5% (by weight) NaCl eq. fluids at 170° to 215°C. Silver spatially and perhaps temporally associated with resurgent rhyodacite was transported as a chloride complex and precipitated by increased H2S activity or increased fluid pH.

Jan 1, 2002

By Irene Bendanillo, Canon Cheung, Justin Lianides, Derek Penrice

The SLAC National Accelerator Laboratory’s two-mile-long particle accelerator generates the world’s brightest X-rays from its Linac Coherent Light Source (LCLS) freeelectron laser. This facility has driven groundbreaking discoveries in medicine and industry. The LCLS-II-HE project will provide a significant increase in laser energy, allowing cutting-edge research in fields including biology and environmental science. A key project component is the Low Emittance Injector Tunnel (LEIT), a 240-foot-long tunnel to be built alongside the existing accelerator and connected to it via a 30-footlong Transfer Tunnel. This paper discusses site and scientific constraints that led to the selection of the LEIT configuration: tunnels to be constructed using the sequential excavation method in mixed-face conditions comprising native rock and placed backfill, and critical design considerations including protection of overlying and adjacent historic structures and structural accommodation of near-fault seismic loading.

Jun 13, 2023

By L. P. Meade

The need to feed an established talc mill from a crude are source located closer to the mill prompted the drilling in 1986 of a previously mapped talc-carbonate deposit. This talc-bearing rock had never been considered as a potential source of crude talc are because of the high carbonate content and other deleterious minerals that were observed in outcrops. Selective mining, in-pit grade control and creative processing has allowed this deposit to be developed into an orebody. By definition, an orebody has to be a source of positive cash flow. With industrial minerals, this is determined as much by market acceptance as by are tenor.

Jan 1, 1992

By J. E. Murphy, Y. Topkaya, R. E. Johnson, B. R. Palmer, D. K. Dysinger, R. B. Bhappu, A. E. Clark

The U.S. Bureau of Mines utilized a central composite experimental design to investigate leaching kinetics of pure chalcopyrite in the sulfuric acid-oxygen system. The six factors studied were oxygen pressures of 150, 300 and 450 PSI, leach temperatures of 35O, 65O, and 95O C, oxygen-to-chalcopyrite mass ratios of 0.5, 1.0 and 1.5, leach times of 8, 16 and 24 hours, initial acid strengths of 0.6, 1.2 and 1.8 g H,SO,/g chalcopyrite and pyrite to chalcopyrite mass ratios of 0, 1, and 2. Chemical analysis and oxygen consumption measurements indicatedthat leaching occurs through three consecutive reactions. Temperature was the primary determinant of leach rate and solution acidity was the primary determinant of oxygen consumption, sulfur oxidation, and activation energy.

Jan 1, 1993

By S. Kelebek, G. W. Smith

Four samples of galena, each prepared differently, dry ground chalcopvrite and real gar have shown various quantities of liberated sulfur corresponding up to nine equivalent monolavers on their surfaces as determined by the solvent extraction/UV analysis of sulfur using ethanol. The pretreatment of a dry ground galena sample with acidified ammonium chloride or neutral, saturated sodium chloride solutions rendered the mineral readily floatable. The collectorless floatabilities of galena pretreated with the former solution and of drv ground chalcopvrite have been evaluated in reference to the natural floatability of sulfur using the critical surface tension of floatability approach with aqueous methanol solutions. It is shown that the amount of sulfur- on these samples can be correlated with their flotation rate, which was found to he first order within the critical surface tension range. The larger the concentration of surface sulfur, the faster the sulfide mineral floats, thus, the greater its flotation rate constant.

Jan 1, 1990

By K. C. Kocsis

Underground ventilation systems, which require electricity to operate the fans and fossil fuel for heating in winter, can account for a significant portion of the energy consumption of mines. Recent studies have shown that the ventilation system in deep and highly mechanized metal mines could be responsible for 40 to 60 percent of their overall energy consumption. Presently, underground ventilation systems are designed for peak air volume requirements, which usually occur well into a future stage of the mines’ operating life. As a result, during their early operating stages, the intake air volume of the mines could be well in excess of their true air volume needs. Such ventilation systems could be considered as uneconomic, and to remain competitive the ventilation design needs to improve while the mines are trying to reduce energy consumption and their carbon footprints. This paper introduces a new mine ventilation design method where an underground base-metal mine’s ventilation system is designed by integrating discrete-event mining process simulation (DES) with mine ventilation modeling techniques. Furthermore, based upon the output data generated by means of discrete-event mining process simulations, the air volume requirement for the operating life of the mine is determined for “traditional” versus “activity-based” ventilation requirements. The output data generated through ventilation simulations are then used to quantify the economic and environmental benefits of an activity-based ventilation delivery system.

Jan 1, 2018

By Stanley J. LeFond

After two disappointing years where most industrial minerals posted decreasing production, 1981 saw an increase in production over 1980, or at least in status quo. Several commodities did, however, post significant gains. For example, bromine posted a 14% increase; fluorspar production dropped 21% in 1980, but gained 24% in 1981; and sulfur production increased. However, perlite was off 13% and manufactured sodium sulfate off 18% in 1981, while natural sodium sulfate production remained almost even with 1980. In fact, many industrial minerals production either remained constant, increased, or decreased only slightly over 1980. Increasing energy costs had their impact on industrial minerals in 1981. Hopefully, the recent downward trend in energy costs, at least gasoline, will financially help some of the more marginal plants. The 1979 shortage of rail cars that did not carry through 1980 also did not carry through in 1981. Rail rates increased 12.8% over-all last year, while average freight rates for industrial minerals increased 15.5%, according to Neil Johnson, consultant. Also, the trucking industry posted a 5-6% decrease in rates due to deregulation. All in all, we in the industrial minerals section seem to be holding our own at least. Stanley J. Lefond Contributing Editor

Jan 5, 1982

By C. T. Holland

Coal mining has been an important industry in the Appalachian area for many years. This is particularly true in the northern part of the area, namely, in Pennsylvania, West Virginia, and Ohio. Also, in the south a great deal of mining activity has been carried on in Alabama, Kentucky, and southwest Virginia. Some of the by-products of this activity has been the production of mineralized water from the mines in copious quantitites. The southern Appalachians have been somewhat more fortunate in that the water there has had a considerable amount of alkalinity in it, which has to a large extent eliminated some of the more undesirable aspects of mine drainage. Northern Appalachia, including central and western Pennsylvania, the Monongahela basin in West Virginia, and the Appalachian area in eastern Ohio have not been so fortunate in that coals in those areas and the top and bottom rock have, in many cases, shown considerable quantities of pyrite, and the water does not carry the carbonates found farther south.

Jan 1, 1969

By N. L. Bingham

The mining industry&apos;s image is molded by what the general public knows, or thinks they know about mining. As we prepared for the production of Caterpillar&apos;s educational film, Common Ground, we first had to find out exactly what the public perceptions about mining were. Before we could educate people about mining, we had to find out what they already thought. As we broke down those perceptions, we were able to narrow our focus to relevant, realistic approaches for the film. We found out what people didn&apos;t know about mining. And most importantly, we singled out the facts they should know... facts that could create more favorable attitudes. This research was instrumental in our final direction for the Common Ground project.

Jan 1, 1994

By P. Bevilacqua, G. Ferrara, M. C. Williams, T. P. Meloy

Tabling is an old environmentally friendly separation unit operation. This paper models shaking tables and explores the action and design of riffles on shaking tables. By reassessing riffle shape and riffle patterns, significant improvements in tabling performance appear feasible. While table sales appear at their nadir, a high-tech environmentally friendly table may have a significant market in the coming decade. Riffles on a shaking table impact particle separation. Particles are affected by riffles and their exit position on the table is dramatically changed, Riffle shape determines how much the riffle will influence a given material. Moreover, riffle patterns influence the concentration of a given material and its exit points on a table. This effect of riffle placement and design is modeled in a spreadsheet. Major performance and separation improvements may he expected by improved table design. Two physical laws of tabling have been derived. These laws aid in the design of sophisticated high-tech tables.

Jan 1, 1995