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By B. DANIEL MARJAVAARA, I. A. SOFIA LARSSON, ANNA-LENA LJUNG

The flow field and coal combustion process in a pilot-scale iron ore pelletizing kiln is simulated using a computational fluid dynamics (CFD) model. The objective of the work is to investigate how the thermal effects from the flame affect the flow field. As expected, the combustion process with the resulting temperature rise and volume expansion leads to an increase of the velocity in the kiln. Apart from that, the overall flow field looks similar regardless of whether combustion is present or not. The flow field though affects the combustion process by controlling the mixing rates of fuel and air, governing the flame propagation. This shows the importance of correctly predicting the flow field in this type of kiln, with a large amount of process gas circulating, in order to optimize the combustion process. The results also justify the use of down-scaled, geometrically similar, water models to investigate kiln aerodynamics in general and mixing properties in particular. Even if the heat release from the flame is neglected, valuable conclusions regarding the flow field can still be drawn.

Apr 20, 2021

By J. E. Gray

Before specifications are discussed it may be well to define the term "Mineral Aggregates." Professor K. B. Woods (1) defined "Mineral Aggregate--An aggregation of sand, gravel, crushed stone, slag, or other material of mineral composition used in combination with a binding medium to form bituminous and portland cement concrete, macadam, mastic, mortar, plaster, etc., or alone as in railroad ballast, filter beds, and various manufacturing processes, such as fluxing, etc. " This definition is too all inclusive for the purposes of this paper; therefore, this discussion will be confined to specifications for natural aggregates which means sand and gravel and crushed stone, and limited primarily to coarse aggregate which is aggregate larger than one-quarter inch in size. To the uninitiated, this may seem to be a very limited subject on an unimportant material. However, aggregates are essential in all types of construction. The tonnage and value of these two aggregates produced in the United States during 1959 as reported by the Bureau of Mines were as follows: Sand and Gravel 729,895,000 tons valued at $728,527,000 Crushed stone 581,721,000 tons valued at $824,411,000

Jan 1, 1961

By J. Kretschmann, N. M. Smith, J. F. Brune, P. Goerke-Mallet

Coal production and coal use for electric power generation are diminishing worldwide. Germany will phase out lignite mining as well as lignite and hard coal-powered electricity generation by 2038. In the United States, coal production has dropped by more than 50% since 2006, including in key coal production states like West Virginia and Wyoming (EIA 2021). Closing mines and power plants across entire mining regions has significant socio-economic impacts. Existing industries must be focused on the post-mining economy by attracting new industries, and implementing job retraining programs for displaced workers, as former mining regions transition towards agricultural, industrial and recreational use. This paper examines the German “exit from coal” under the 17 UN Sustainability Goals and illustrates the complex procedures, interrelationships, risks, and rewards of the transition towards renewable energy sources, including wind, solar, hydrogen, and bioresources.

Mar 2, 2022

By C. Bryce

Rhenium is primarily recovered as a byproduct from molybdenum roasting circuits. However, rhenium is also present in copper heap leach solutions at very low concentrations, and this represents a potential new rhenium source. Freeport-McMoRan (FCX) has developed a new process using carbon adsorption followed by ion exchange or solvent extraction to concentrate rhenium from less than 1 ppm to 15 g/L. The product is compatible as a feed to an existing rhenium processing plant. A pilot plant operated at Freeport-McMoRan?s Sierrita Mine has demonstrated the technical and financial feasibility of this new process. Copper heap leaching dissolves more than just copper from the copper ore. Several metals can be identified in leach solutions at concentrations of financial interest, rhenium in particular. Rhenium spot prices ranged from a yearly average of $1,070/kg ($483/lb) in 2005 (Magyar, 2008) to $10,400/kg ($4,706/lb) in 2008 (Polyak, 2013). The spot price in September 2013 was approximately $3,000/kg ($1,357/lb) of rhenium (Metal Bulletin, 2013). Several facilities at Freeport-McMoRan have very low rhenium concentrations in their copper leach solutions, ranging from 0.1 to 0.7 mg/L. The large quantity of solution available, if coupled with an attractive rhenium price, means that the rhenium contained in leach solutions may represent a significant value if a method of extraction could be developed. Testing has confirmed that rhenium adsorbs onto activated carbon much more selectively than other metals in the pregnant leach solution (PLS). A 100-gpm pilot plant was constructed to verify the lab-scale results on a larger basis and establish operating parameters for a full-scale operation. This report summarizes the initial technology development and pilot plant operation.

By ANDREW HOBERT, Maoming Fan

Low-cost and environment-friendly green froth flotation modifiers of plant origin, such as guar gum, carboxymethyl cellulose (CMC), and starch, have been used in flotation of some sulfide and non-sulfide minerals. Certain green modifiers may be used as dispersants, flocculants, depressants, or activators. The functions of green modifiers in froth flotation highly depend on their molecular composition, flotation slurry chemistry, hydrodynamic conditions, etc. This paper will discuss the fundamentals, current applications, and potential new applications of guar gum, CMC, and corn starch in valuable minerals (phosphate, potash, and iron ores) and the unwanted gangue minerals (silica and clay minerals) flotation. In this study, improved flotation performance was achieved using some green modifiers in flotation columns with the more plug-flow environments than in conventional flotation cells approaching perfectly mixed conditions. This is because the hydrodynamic cavitation-generated ultrafine bubbles could help bridge ultrafine particles to form aggregates, promote the formation of flocs, and increase the stability of flocs.

Jan 6, 2022

By C. Opoku-Ware, M. Kukay, P. Conrad

"This project is exploring the potential for developing trees tolerable to degraded un-reclaimed mine site soils and tailings as a solution to re-establishing long-term tree growth on those sites. The project incorporates growing tree seedlings in an underground greenhouse grown from seeds planted in the degraded mine soils in which they will eventually be planted. The outcome of the project is expected to lead to a successful solution for re-establishing tree growth in soils and tailings containing high metal concentrations with minimal post-planting human intervention. The research is being conducted in an underground greenhouse located 100 feet below the surface in the old Orphan Boy Mine Underground Mine Education Center (UMEC) located on Montana Tech’s campus in Butte, Montana. INTRODUCTION In an effort to improve Butte Area One natural resources, the research project was proposed to help restore tree growth in the Butte Priority Soils Operable Unit Boundary (BPSOU). Research by Blicker, et al. (2003) found that, the BPSOU, which is part of the Silver Bow Creek/Butte Area National Priorities List (Superfund) Site within and near Butte, Montana has multiple historic mining sites situated entirely within the urban setting of Butte. Mine wastes and mill tailings, accumulated from over 100 years of gold, silver, and especially copper mining are dispersed throughout Butte, posing health risks to human and environmental receptors. Stabilization of tailings sites is needed to control fugitive dust, prevent run-off of toxic material resulting in subsequent sediment deposition in streams, reducing the volume of water seepage through acidic and heavy metal contaminated material, and improving land productivity and aesthetic VALUES ((Watkin and Watkin, 1982). If successful, the project will help restore water quality and maintain stream flow in Silver Bow Creek where it flows through Butte Area One. Trees native to Butte are being grown in an underground greenhouse located in the UMEC and will be planted in five areas located within the BPSOU designated for tree planting by the Butte Silver Bow government. Growing trees is expected to help restore vegetative ground cover within the watershed contributing to stream flow in Silver Bow Creek. They will prevent soil and tailings from eroding and being deposited in Silver Bow Creek where they could degrade water quality and choke stream flow."

Jan 1, 2018

By Steven Keim, Steven Stansfield, Kevin Andrews

Geotechnical, geological, and hydrogeological fieldwork and data collection for the mining industry is often conducted by younger, less-experienced staff members. In many cases, fieldwork personnel are recent college graduates or are otherwise relatively new to the mining industry. Due to busy schedules, staffing shortages, project budgets, and in some cases, poor management, new fieldwork hires often do not receive thorough training. In the past and the present, many workers in the mining industry learn(ed) by “doing.” While this is still considered to be the most practical approach and the easiest way for a company to determine the skill set of an employee, there is always some risk involved in the “feet to the fire” method. The reality is that field personnel are often collecting data on which major operational decisions will be made or on which regulators will base enforcement decisions. Inadequately trained or inexperienced field personnel may collect inaccurate data or fail to recognize key conditions that may influence decisions made by regulators, design engineers, mine managers, and corporate leaders. Even the best engineers may come to incorrect conclusions if they are starting with poor input data. Decisions based on inaccurate data often result in delays, budget issues, unsafe conditions, or even worse consequences. This paper provides numerous mining industry examples of incidences where inaccurately collected field information did, or could have, resulted in major adverse consequences. The paper also offers some simple approaches to minimizing the potential for such problems.

Jul 1, 2023

By Y. Wang, G. Xu, N. A. Amoah, A. Kumar

Mining-induced coal dust causes various respiratory diseases to mine workers, such as coal workers’ pneumoconiosis (CWP). Current available underground monitors are expensive, heavy and only measure mass concentration. These disadvantages limit them for regulatory sample monitoring purposes only while personal exposure levels for most miners remain unknown, risking miners to potential overexposures. Low-cost light scattering PM sensors offer a potential solution to this problem with capability of high spatio-temporal resolution PM characterization. However, these sensors require careful calibration before they can be applied in mining environments. There is basically no comprehensive study in the literature using a standard protocol assessing these sensors for coal dust monitoring. With the aim of calibrating the PMS5003 sensors for coal dust monitoring, we design the calibration method and system to calibrate these low-cost PM sensors coal dust monitoring. Working principles of present coal dust monitor and low-cost sensors are presented in detail. The linear regression calibration model which is used for the sensor calibration is further described. Sensor calibration and evaluation protocols are comprehensively compared and discussed. This investigation reveals the feasibility of low-cost sensors for real-time personal coal dust monitoring in underground coal mines.

Mar 2, 2022

In early June, Rio Tinto?s chief executive officer Tom Albanese said that he expected demand for iron ore, aluminum and copper to double in the next 15 years. Driven by global industrialization and urbanization, Albanese said during his company?s annual general meeting that to meet the demand in 2030, the additional supply required will be equivalent to replicating the iron ore output of Australia?s Pilbara region every five years, adding another aluminum production complex the size of Canada?s Saguenay every nine months and developing another copper mine the size of Escondida, in Chile, each year.

Jan 1, 2010

By K. W. Grubaugh

The recently enacted federal surface mine law (P.L. 95-87) will increase further the complexity of securing a reclamation permit. This law intensifies the need to present the required reclamation plan in a thorough and comprehensive manner. One plan format, that used in construction performance contracts, offers promise of filling this need. Reasons for using the format of expressed, bilateral, negotiated contracts common to the contruction industry, and the salient aspects of an application which uses this format are reviewed. Advantages of this procedure are seen to be improved mine planning, awareness of the total design job, potential for improved speed of permit acceptance and improved cost control.

Jan 1, 1978

By G. T. Austin

This is an overview of the gemstone industry with special attention on particular states within the united states. The U.S. Bureau of Mines, Department of the Interior compiled and analyzed the information contained in this report. The report should be viewed as a current "still photograph" of a dynamic system. The information presented on a specific gemstone or for a specific state can and will change with time. This overview presents historical and reference information on the principal gemstones and their production in certain states. The report is not a definitive work on gemstones within the select states or United states.

Jan 1, 1995

By Gary English

"Tunnel safety is evolving as science, engineering and technology make advances. Applicable safety codes and standards simply do not cover all the potentials of design, construction and operation. This paper reviews a series of tunnel projects code gaps in Seattle USA that were uncovered during the design and construction of a new highway tunnel, conversion of bus tunnels to combined road and rail tunnels, new rail tunnels using TBM and NATM, conversion of a road tunnel to light rail, and retrofit of an existing road tunnel to add lanes and improve safety systems. The perspectives of the ‘fire code official’ (Authority Having Jurisdiction) on methods to identify and resolve gaps in safety code and standard regulations, while garnering the consensus of the owner, designer, and contractors are presented. Additionally, the emergency responder command perspective on safe tunnel design, tunnel rescue during construction and operational safety is explained TUNNEL SAFETY EVOLUTION The underground has become nearly the only option to provide essential transportation corridors to continue our economic growth in key global areas. Tunnels are not built on a whim. Often significant portion of a regions wealth are invested to meet current, and hopefully future transportation demands. There are more transportation tunnels being built now than at any time in the planets history. The location of these tunnels is often selected for us based upon regional demand. Most commonly under densely populated urban centers and between populations’ centers to bypass geologic conditions like mountains and water bodies. Tunnels are being built in unforgiving soils, between tectonic plates, in extremes environmental conditions and often, under the very heart of the highest density population centers on the planet. All of these locations can bring with it conditions that challenge our common assumptions about safety. These extraordinary locations and soils create risks for both those constructing the tunnel, and in design engineering to meet the ‘minimum’ requirements at the lowest costs. There is lengthy history of above ground safety. Most countries and major local jurisdictions have adopted, or created safety requirements for the construction of above ground buildings. Through decades of use, these safety requirements have evolved, changed and been expanded to cover a wide gamut of actual and potential safety risks. However, the use of the underground for tunnel transportation corridors has grown exponentially with limited attention to safety requirements."

Jan 1, 2016

By David M. Koogler

If you are contemplating starting a small coal mining operation there is a good possi¬bility that you can not afford it. If you, have already started, you may be on the road to bankruptcy. If you are a small but well established operator you may be trading dollars, or even dissipating your capital, equipment and other assets. A bleak outlook? Yes! Meant to be discouraging? No! Just a reminder that, with todays costs of doing business, high interest rates, rapidly increasing costs and decreasing sales prices, a small businessman/miner had best watch closely or he will be mired in something worse than a soft bottom - namely a cash and credit shortage, and in too many instances In recent times, bankruptcy. We will not dwell on what happens once you are that far gone, though I could cite a good example. But, let us look at what should be done to avoid such a catastrophe.

Jan 1, 1981

By Richard O. Rouse

Today, I want to challenge this audience by charging each of you to be a greater manager and superior engineer to manage and engineer our way through the 1980's and profitably overcome all the present and proposed government regulations. May of the present and proposed regulations will tax you and your company's management and engineering to the brink of physical and monetary exhaustion, but I believe we can succeed and coal can be America's answer to her hungry energy needs. To put our 1980's challenge into perspective, I want to give two great challenges we must overcome. First - We must improve on our process of compliance to new government regulations in the technical and equipment end of our industry. The Lord said, "Let There Be Light". MSHA said, "Let there be light in underground coal mines". Since that time, we have lived through an unmanageable and tremendously costly period of compliance.

Jan 1, 1980

By R. L. Grayson

In 1995, Congress abolished the Bureau of Mines in the Department of Interior but preserved the safety and health research functions being performed at the Pittsburgh and Spokane Research Centers. These functions were transitionally housed in the Department of Energy before permanently merging with the National Institute for Occupational Safety and Health (NIOSH), Department of Health and Human Services, in October 1996. Since the merger of the former Bureau with NIOSH, there has been an active evaluation of ongoing research activities, significant interaction with stakeholders, and the development of a process leading to "data informed" priority setting. This presentation will review current surveillance information concerning the level of injury and disease from mining work and will discuss how research priorities are evolving to improve the contribution of research to the prevention of injury and disease.

Jan 1, 1998

By J. C. Bradbury

The Illinois State Geological Survey's program in industrial minerals is twofold-the gathering of information on mineral raw materials and the generation of data on the use of these materials. The first function is carried out by the Industrial Minerals Section and the Clay Resources and Clay Mineral Technology Section of the Geological Group, and the second is the responsibility of the Chemical Engineering Section of the Chemical Group. Gathering in formation on raw materials includes both mapping of resources and fundamental geological research. Recent and current research projects include studies relating lithologies of limestones to their physical properties, investigation of sulfur dioxide reactivity of various types of limestone, lithostratigraphic studies of limestones of Mississippian age, investigations of heavy minerals in Cretaceous, Tertiary, and Pleistocene sands, studies of the environments of clay deposition, electron microscope studies of clays and limestones, and investigation of long-term expansion in ceramic products. A relatively recent development that relates more to dissemination of information than to research is environmental geology. This affects the Survey's industrial minerals program chiefly by stimulating the study of rock and mineral resources in metropolitan areas and reporting the results for the land- use planner as well as the engineer or mineral producer. The Survey's program of research on the use of industrial minerals was expanded and diversified in 1966. Incorporating a minerals beneficiation lab, the program is designed to develop new uses for existing mineral resources and to assist producers in implementing these ideas: Projects of the minerals engineering program have included the separation of a feldspar concentrate from certain glacial outwash and river sands, recovery of kaolinite from the waste from silica sand operations, development of the use of an Illinois clay as a binder for pellets, and investigations into the use of fly ash and fluorspar mine tailings.

Jan 1, 1970

By R. Benito

The publication of the Lerchs Grossmann paper in 1965 outlining a threedimensional graph algorithm for ultimate pit definition set the standard for the mining industry regarding pit optimization. Although the algorithm provides a solution from a static standpoint (i.e., assumes instantaneous mining), it is widely used for commercial packages to generate ultimate pit limits and intermediate phases. However, the solutions delivered are presented in canned reports lacking connection to the original data, which prevents further data analysis and extended reporting. The approach presented in this paper attempts to overcome such barriers by performing openpit optimization through databases. An adaptation of the Lerchs Grossmann graph algorithm is used to generate nodes, arcs and tree structures in customized tables to determine the maximum closure of a graph.

Nov 1, 2013

Since 1955 Gaspe Mines has produced 144 million tonnes of ore, averaging 0.87% Cu, mined from two open pits and underground workings. In 1994, four exploration drill holes discovered a buried porphyry/skarn Cu-Mo deposit at depths of between 1000 m and 1700 m below the top of Porphyry Mountain. The mineralization and alteration associated with the Porphyry mountain quartz monzonite does not outcrop. A total of 19,500 m of drilling in 12 drill holes has outlined 200 million tonnes grading 0.73% Cu and 0.08% Mo. Mineralization occurs as veins and disseminations of chalcopyrite and molybdenite. Drilling and feasibility studies continue.

Jan 1, 1998

By J. A. Zimmer, M. S. Hillis, D. Moredock, J. A. Organiscak, A. B. Cecala

Enclosed cabs have been used on surface mining equipment for many years to protect equipment operators from health and safety hazards. The surface mining and quarrying process is a highly mechanized process that generates large quantities of respirable dust. Due to economic factors, more older mining equipment is being used today than in years past. With this older equipment, it is common to observe deterioration of many components on the enclosed cabs, which greatly reduce their protection effectiveness. NIOSH has performed a number of different field studies, as well as a comprehensive laboratory study, evaluating various factors and parameters regarding enclosed cabs. NIOSH has recently completed a cooperative research effort to evaluate the effectiveness of a newly designed unidirectional powered precleaner, filter and pressurizer that brings clean filtered air in at the roof of the cab and extracts all recirculated air near the floor. This research effort provided another example of the enhancement in air quality that can be achieved in an enclosed cab from the implementation of an improved filtration system and by establishing positive pressurization from increased intake air volume and sealing the cab. This testing showed a significant reduction in respirable dust levels in the enclosed cab when comparing baseline versus post-testing results. Since dust levels were similar near the roof and floor of the cab during post-testing, the unidirectional flow pattern did not appear to significantly improve the performance over the conventional design in this study.

Jan 1, 2009

By T. McNulty

The author was privileged to find employment as a uranium mill chemist for The Anaconda Company while working his way through school in the mid-1950s. He then served Anaconda in various technical and management positions until 1980. This paper describes the prevalent technologies employed by uranium producers, briefly describes various mines and mills in the U. S., and memorializes a few of the thousands of men and women who contributed to the U. S. Uranium Boom. Following isolation of uranium as an element by M. H. Klaproth in 1789, uses of uranium were confined primarily to pigments, glass coloring agents, and ceramic glazes. In 1896, Antoine Becquerel found that uranium is radioactive, releasing particles and energy as it decays. In 1898, Pierre and Marie Curie isolated radium from uranium and learned that it can be an effective treatment for some types of cancer. In 1939, it was discovered that the isotope U235 is fissionable1 . Up to this point, nearly all uranium production was from pitchblende concentrates made in Bohemia, Canada, and the Belgian Congo. In 1938, only about 5 percent (23.85 short tons) of global output was produced from ores of the carnotite mineral that were being mined in the U.S. By the early-1950s, physicists in many countries had begun to recognize the potential for nuclear chain reactions. Ernest Rutherford (UK), Frederick Soddy (UK), and Leo Szilard (US) explained transmutation of elements and formulated the principle of “atom splitting”. In 1934, Marie Curie’s daughter, Irène, and her husband, Frédéric Joliot, identified uranium as the most viable source for this new form of energy. The basic fission process was unraveled by German scientists in December 1938. After Hitler’s army seized the uranium deposits in Czechoslovakia, many feared that Germany would build the first nuclear weapon.

Mar 2, 2022