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By G. Potts, K. Raiber, T. BoBo

Effective control of balling line circuits is a problem taconite companies have been dealing with for over thirty years. The sensitivity of balling circuits to changes in moisture, bentonite, concentrate particle size, and other operating parameters are the main reasons for control problems. This paper presents test results and describes the integration of existing instrumentation with a digital image analysis system on a balling circuit. This work has the goal of developing control strategies to automatically adjust water spray and bentonite addition, to optimize the size distribution on the roll screen and reduce the variability in control between balling attendants, resulting in more consistent greenball product quality.

Jan 1, 2003

By R. B. Krog

Airflow patterns in longwall bleeder systems are affected by gob permeability and porosity and the condition of the gateroad entries after mining. As longwall panels are mined, areas of the caved zone and portions of the remaining gateroad entries become inaccessible, making direct ventilation measurement impossible. Mine operators are left to estimate direction and amount of airflow in the gob and the surrounding gateroads. The most readily available locations are where air enters the worked-out area, approved measurement point locations (MPLs) and/or evaluation points such as bleeder evaluation points, intake evaluation points, and the outer bleeder entry. Ventilation models (network or Computational Fluid Dynamics, CFD) can model the gob and the surrounding bleeder system but calibrating these models is difficult without field data. NIOSH installed a tube sampling system ahead of a longwall face and, as the face retreated, released a slug of tracer gas (SF6) to determine transportation times and flow rates in the inaccessible gateroads. The data was used to calibrate both network and CFD ventilation models for a longwall panel. Both model types were used to predict the airflow patterns in the gob and to determine the airflow rate from the longwall tailgate corner back to the bleeders.

Jan 1, 2011

By Cheryl L. Mardock, Michael D. Strickler

The Bureau of Mines is examining mineral deposits bearing strategic elements such as cobalt, for which the United States heavily relies on imports. The Turner-Albright volcanogenic sulfide deposit in southwestern Oregon is marginally economic based on its gold content and associated silver, copper, zinc, and cobalt values. Bureau research on the Turner-Albright deposit was performed (1) to evaluate domestic cobalt recovery as a byproduct of gold production from massive sulfide ores; (2) to develop an analogue of modern sea-floor polymetallic deposits to determine the economic potential of the deep-sea resources; and (3) to compile information on the geochemistry and genesis of the deposit that can aid in future onshore exploration. Cold was introduced as near micrometer-sized disseminations by exhalative hydrothermal fluids near sea-floor vent sites and by late influxes of mineralizing fluids into lower zones of brecciated sulfides and basaltic fragments. Cobalt is a substitutional element in pyrite that occurs in outlying halos around original vent sites. Mineralogic studies conducted with a scanning-electron microscope and an electron microprobe determined that none of the ore minerals are amenable to traditional beneficiation methods such as gravity and flotation. An experimental oxygen pressure-leaching procedure developed by the Bureau has proven successful in treating such complex ores.

Jan 1, 1990

By Jan A. Nemcik

Steel mesh has been used successfully for many years to control friable roof conditions and prevent loose roof and rib material from caving into the roadway. Despite its extensive use, the installation of steel mesh is difficult to automate and many other products have been evaluated as an alternative for skin control. Ideally, the properties of these new products should be similar or better than those of the steel mesh. In particular, development of a strong and resistant shell that minimizes movement along the fractured rock and coal surfaces between the bolt anchors is recommended. A strong surface adhesion and the strength of a reinforced polymer skin can provide the necessary toughening mechanism required to enhance roadway surface support by forming a reinforced polymer/rock surface layer. Most of the Thin Spray-on Liners (TSL) evaluated in the mines are weak with slow curing times, and the plastic mesh currently used to support the coal ribs is relatively weak. Therefore, neither material can seriously compete with steel mesh. Currently, a new polymer product that cures in seconds and forms an instantaneous strata binder that surpasses the properties of steel mesh is under development at the University of Wollongong.

Jan 1, 2009

During the past decade, since the appearance of Popoff's (1966) review of grade tonnage calculations, it has become evident that defining a new method which could be followed step by step by a technician and which would improve reserve estimation was not a simple thing to do. Some concepts have emerged though, and most definitions of ore reserve now require a statement of reliability (USGS, 1975; and Zwarten-dyke, 1976). Exactly how the reliability should be computed is not a straightforward process. It also became apparent that not only was reliability a requirement but that additional questions such as how to predict mining re- serves from geological reserves were to be asked. In fact what became obvious is that specific models have to be designed for each type of mine and for each type of question which is asked. Most methods can be encased within a unique general geostatistical, model, but it takes considerable custom tailoring, and there are still questions that are left unanswered. In this chapter, before giving techniques, we intend to first review what should be required from a grade tonnage calculation done at the exploration stage. If the final objective is still to specify a tonnage and grade, with eventually a reliability, many qualifications have to be made before quoting, and of course, calculating these two numbers. Then the currently avail- able methods will be reviewed and future trends will be shown; finally a few case studies will be given and recommendations about the choice of a model will be made.

Jan 1, 1979

By Roland C. Walker

Traditional headed rebar has existed in the mining industry as a ground support product for many years. The head of a rebar bolt is most commonly produced by hot upset die forging. Upset die forging produces a rugged, simple head that performs well. Certain elements of the head must comply with regulatory standards, such as ASTM F432-95, which offers a standard test procedure to ensure quality of the product. The head style produced by all major manufacturers has been optimized to reduce manufacturing costs, provide greater miner safety and provide an excellent performing product. Observations were made in some mines of heads failing under in-situ loading. These observations could not be replicated according to the ASTM testing method. This paper highlights the problem and how a solution was developed. The development includes pictures of in-situ failures from the underground operations, laboratory replication tests indicating how this loading occurs, and then the use of this calibrated test method to validate the new design created.

Jan 1, 2009

By F. Romero, L. Yacher, M. Orchard

Specific software tools for Statistical Multivariate Analysis combined with real time process data were applied to Concentrator Plant at Compañía Minera Doña Inés de Collahuasi SCM in Chile, basically to two Mill Lines, each one with one SAG mill (32’x15’8MW)and one Ball mill (22’x36’9.7MW). The main objective was to empower the operator actions using process patterns references instead of process variable set-points. Pattern clustering and the analysis of pattern deviations regarding normal or desired pattern, allows for improvements in process control and the further implementation of soft sensors for those variables not included in the initial model.

Jan 1, 2003

By E. De Souza, J. F. Archibald

"Many underground mines use cemented backfill to mitigate environmental effects associated with tailings disposal. The large energy needs associated with mine backfilling and cement production operations create significant CO2 and Greenhouse Gas Emissions. This paper introduces post-consumer glass as an alternate, equally effective and lower cost binder agent strategy for cement in backfill that may be implemented to assist in reducing solid waste production, lowering energy costs, and restricting Greenhouse Gas Emissions. Extensive engineering testing, consisting of pipe flow loop tests and strength tests, has been implemented in order to demonstrate the technical feasibility of process integration within industry. An economic analysis has demonstrated that glass is competitive in cost relative to cement and a socioeconomic study has further indicated that the utilization of glass in mine backfill would create a new market for waste glass that requires less processing and reduces costs."

Jan 1, 2005

By E. Berrezueta

Automatic digital phase imaging should yield unbiased and representative characterization of gold ores. However, this is not a simple task due to low gold grades, fine grain size, possible complex mineralogy, nugget effect, etc. A critical test was done by two methods, using the same sections of a gold-rich ore: with an optical (OM) and with an electron microscope (EM). In general, the two methods are consistent and useful for ore processing. There are some minor differences e.g. the detection of very fine gold grains is enhanced by EM.

Jan 1, 2001

By Osvaldo A. Bascur, J. P. Kennedy

Companies have installed powerful desktops for their personnel and instrumentation and control systems in their plants. These desktops are, in many cases, connected to a company intranet. Still, process engineers have to obtain their data manually. Engineers use process calculations from manually calculated averages from the plant; field operators collect equipment data on log sheets; and maintenance engineers collect critical information on log sheets. All of this information resides in individual machines. What are the strategic tools that will enable collaboration between them? How can operators, engineers, and managers access plant information to proactively increase their effectiveness in process troubleshooting, plant debottleneclung, aligning with business strategic and customer demand, satisfying environmental and safety regulations, developing capital projects, and implementing control strategies? A nonintrusive environment at the desktop is required to provide the process information to these workers. How can value be added to MS Windows technologies with the legacy systems at a minimum cost? There is no straight answer; however, there is a proven framework to leverage the large investments in new technologies. Objects and components are changing the way everyone relates to their computer and networks. Three examples will be described to demonstrate paradigm change. Today, process engineers can access data at the required level of detail for analysis of critical process variables at their desk or remotely. 1. Process Troubleshooting and Analysis: The engineer can develop an inferential calculation, trigger a process advisor to deter- mine the behavior of the units for the last day, and get the population of a set of batches (heats, blocks, rolls, sheets, etc). 2. Process Control and Optimization: The engineer can connect to a process simulator at steady state or a dynamic simulator of the process to evaluate new control strategies or process unit line-ups and use the process simulator as a process observer for fault diagnosis. 3. Collaboration with Accounting and Maintenance: The engineer can review reconciled data and the process mass balances, suggest maintenance cleaning or recalibration of flowmeters, and evaluate key control performance of all advanced controls.

Jan 1, 1999

The day after I reached New York, on January 30th, John Ryan of Anaconda told me where they wanted me to go. Late in 1916 the Russian Czar, desperate for money and supplies with which to carry on his unhappy share In the first World War, sent emissaries to the United States to see if our great mining companies might be interested in trying to find mines and to bring them to production in the millions of acres of the Imperial Estates in Russia and Siberia. It looked like a long chance as no one knew whether or where there might be important ore bodies. Even if they found them it might be a hopeless task to equip them under wartime conditions But the American copper companies had plenty of money and they were used to taking risks. They made a supersecret agreement with the Czar's deputies to send an exploring expedition to Russia at once I never learned the names of the other companies but Anaconda was to man- age the venture. Horace Winchell, then the leading mine geologist In the United States, was to be in charge of operations. Charles Janin, an eminent placer and dredge expert, was to study chances for producing gold and platinum. Though at 33 years of age I was much younger than the others, I was chosen to hunt for copper and other valuable metals. Charles Boynton, a business man who had lived in Russia and had married an attractive Russian woman, was to join the party and carry on any necessary financial or diplomatic affairs. He had gone on ahead to arrange for our reception Finally a graduate student from Ann Arbor named Steinberg was to go along as Interpreter. We soon found out that if his Russian was no better than his English his interpretlng couldn't be trusted too much I knew nothing about the millions of square miles In Russia and Siberia, and even less about what mineral deposits might be found, but I was delighted at the prospect. I was treading on air for the few

Jan 1, 1976

By D. S. Choi

The paper contains a subsidence measurement taken over a room and pillar panel of a mine located in northern West Virginia. A total of 72 monuments were used to determine a three dimensional view of mine subsidence. In addition, the results of measurements were used to compute ground strains with the use of a numerical model.

Jan 1, 1982

By A. E. Halim, J. F. Brune

The 2006 Sago, Darby, and Aracoma mine disasters in the United States (US) forced the US government to implement the 2006 MINER Act and additional regulations that require all US underground coal mines to install and maintain refuge chambers to manage entrapment emergencies, in particular, fires and explosions. However, there is a debate on whether barricading in refuge chambers is a good strategy to survive such emergencies. Australian coal mines are not required to use refuge chambers and, instead, have adopted a strategy that focuses on instructing and training miners to self-escape to the surface. This paper analyzes merits and problems of using refuge chambers and self-escape to the surface to manage emergencies in fires or explosions in an underground coal mine. The authors found that the use of refuge chambers may not be the best strategy during extensive fires or when multiple explosions happen. In these situations, mine rescuers are unlikely able to extract miners who are sheltered in chambers and conversely, self-escape may save more lives than sheltering. Chances for successful self-escape are further improved by regular, externally assessed training such as Level 1 Emergency Exercises required in the Australian State of Queensland. These exercises put pressure on mine operators to ensure and maintain the effectiveness of their emergency management system.

By F. F. Aplan

Prologue Antoine Marc Gaudin (Fig. 1) was truly a giant in the field of mineral processing, and his shadow is still cast long on our profession. "Tony," as his students affectionately called him (but never to his face), came to the United States in 1917 and enrolled at Columbia University where he studied under Professor Arthur F. Taggart. Later, as a lecturer, he wrote his classic comminution paper (Gaudin, 1926). This important work led to his appointment as an associate professor at The University of Utah, where he conducted highly original work on flotation fundamentals that is still widely quoted today (Gaudin et al., 1928-30). In 1929, he was appointed Research Professor of Ore Dressing at the Montana School of Mines in Butte. Shortly thereafter, he published his first book, Flotation (Gaudin, 1932). Because Gaudin could so quickly cut through the fog to get to the essence of a problem, this is still a valuable reference book. It is a valued part of my personal library, and I consult it frequently. Over the next decade, he conducted an outstanding graduate research program at Butte, but, more importantly, he honed his undergraduate lectures and produced the century's outstanding text in the field, Elements of Mineral Dressing (Gaudin, 1939). More than 50 years later, this terse book is still found to contain most of the elements of the discipline. Its sections on the

Jan 1, 1994

By Alfredo Valdivia, Hamed Nejad, Vincent Monaco, William Cao

"The East Side Access (ESA) CM005 Contract - Manhattan South Structures - consists of the installation of the waterproofing and final concrete lining for railroad tunnels, 3-Level Wye track turnout structures, segments of the Main Cavern Station, and a series of Ventilation Structures excavated beneath the existing Metro North Railroad (MNR) Grand Central Terminal. Several key team decisions made collectively by the Construction Manager (CM), Designer, and the Contractor has allowed the scheduled construction duration of 29 months to be maintained. These strategies include the use of alternate design and construction methods, including the use of pneumatically applied concrete lining and precast lining. This paper discusses these strategies, and illustrates how successful teamwork and cooperation during the execution of a large-scale construction project can lead to lowering costs, improving quality, and maintaining the overall project schedule. INTRODUCTION The East Side Access Project The Long Island Railroad (LIRR) currently transports commuters from Long Island into Manhattan, terminating at the already over congested Penn Station on the west side of Manhattan. Once completed, the ESA Project will provide LIRR commuters direct access to the east side of Manhattan underneath Grand Central Terminal. The ESA Project will help alleviate the congestion at Penn Station, which currently accommodate the NJ Transit, Amtrak, and LIRR lines; reduce travel time for LIRR passengers traveling to the east side of Manhattan and facilitate connections to the NYCT Subway System and Metro North Rail Road. The ESA Project includes building new tunnels and facilities under Manhattan and Queens. (See Figure 1).The Manhattan Alignment In the Manhattan segment of the ESA Project the excavation in hard rock of tunnels, cross passages, caverns and shafts has been completed by tunnel boring machines, drill and blast, and road header. The construction of the structural concrete final lining, interior structures and fit-out of the previously excavated caverns and tunnels are currently being performed under Contract CM005 Manhattan South Structures awarded to Michels Corporation and Contract CM006 Manhattan North Structures awarded to Frontier Kemper Constructors Inc. This paper focuses on the design and construction aspects of Contract CM005 which is the first ESA Contract in Manhattan to successfully construct concrete final linings in pre-existing excavated areas."

Jan 1, 2016

By Changwoo Lee, Jan M. Mutmansky

Introduction Recognition of Coal Workers' Pneumoconiosis (CWP) as a major occupational disease has affected various aspects of the coal mining industry in the United States as well as in almost all major coal producing countries. Regulations related to the control of coal mine dust forced mine operators to modify their mining and ventilation practices. As the coal production record of the last 15 years shows, this had both direct and indirect impacts on the productivity and production costs. To identify the causes of CWP, many research efforts have been made through- out the world. Most of these studies were epidemiological in nature, attempting to pinpoint exposure and seam variables that affected the incidence of the disease. Other studies have been oriented toward the elemental and mineralogical composition of the coal dust in the mine atmosphere and in the miners' lungs. These studies indicate that there may exist some relationships between the characteristics of the coal mine dust and the prevalence of the disease. Some of the variables that are thought to affect the occurrence of CWP are the mass of the dust in the working place, the rank of the coal, the existence of certain trace elements, the free silica content of the coal, and the existence of other minerals in the respirable dust. A more complete description of these previous re- search studies has appeared elsewhere (Mutmansky and Lee, 1984). The behavior of particles in the human lung is known to be governed by their aerodynamic diameter, which is defined as the diameter of a hypothetical spherical particle with unit density that exhibits the same settling velocity as the given particle. Because of this fact, the aerodynamic size distribution of coal mine dust is one of the parameters to be determined along with the other physical, elemental, and mineralogical characteristics. The objective of this paper is to establish a strategy for providing coal mine respirable dust samples for characterization purposes using instruments that classify according to the aerodynamic diameter. In addition, several findings concerning characterization methods will be presented. Choice of Samplers Most of the gravimetric dust collection devices that can be utilized in a mine environment can be

Jan 1, 1986

By T. Winkler, J. Tokarczyk, D. Michalak, W. Chuchnowski, M. Dudek

Engineering Methods aiding Sustainable Development of Mining Systems will be presented, and especially: virtual prototyping for designing of Mining Systems with Health Protection and Safety criteria taken into consideration, modelling and assessment of technical and health hazards that can occur during operation of Mining Systems, creation of knowledge repositories that disseminate safe work methods with consideration of existing language and culture barriers, dissemination of the methods integrating world community and Mining Systems users.

Jan 1, 2011

After the war that was nearing an end In early 1945, regular consulting work for Bralorne, the Bradleys, Pennsalt Chemical Co., and a directorship and occasional consulting for Homestake Mining Co. made it almost certain that in spite of my 61 years I would have enough work to feed my family. But this routine work would not provide enough income to lay up funds for the inevitable future when I could no longer do arduous work. And it would not give me the adventure that had first lured me into mining. Therefore I was greatly relieved as well as pleased when, in the 18 months from April 1945 to November 1946, I was asked to make three of the most adventurous as well as profitable examinations that ever came my way. Pati[n]o Mines, Bolivia The first of the exciting jobs was an examination of the Pati[n]o tin mines in Bolivia. After I had unsuccessfully tried to induce Anaconda to purchase these mines In 1915, the World War I crisis that had forced the half-Indian accountant to try to sell the mines had come to an end. The European market for tin improved dramatically, and "Don Simon" was able to borrow money for expenses while the concentrates were still In Bolivia. He took advantage of the favorable conditions by buying adjacent properties and increasing development work until his Bolivian tin mines were the greatest in the world. And his daughter had marled the French Count de Boisrouvain and was cutting a swath In high International society. Pati[n]o wanted to get rid of the drudgery of running a complicated mining Industry in a remote area In Bolivia when the fleshpots of Paris were much more seductive. An added incentive was the fact that his miners had become unruly and had even threatened his 11fe.

Jan 1, 1976

By J. Paraszczak

Water-powered jackleg rock drills, introduced recently in South African mines are reported to be more efficient, faster and more comfortable to operate than conventional pneumatic drills. A comparative testing of both drill types was performed in Quebec. Based on its results and time studies done in the mines, water-powered drilling has been reviewed with regards to drilling rates achieved, infrastructure needed, side effects, health and safety considerations. This study shows that the application of water-powered drills may help increase footage drilled and improve working environment, but under specific conditions. The examples of such applications are given in the conclusions.

Jan 1, 1995

By Jr. Kirschner

An abandoned waste impoundment located within a portion of the Kellogg, Idaho Superfund site constitutes a field research area for studying the feasibility of recovering heavy metals in-situ from unsaturated mine and mill wastes. A prototype in-situ leaching cell has been evaluated using liquid-phase tracer tests and other hydro-geologic tests prior to introducing a lixiviant. The results of the tests suggest that: (1) the cell can be operated excursion-free with a low-density lixiviant at an injection/withdrawal rate of approximately 0.32 l/s; and (2) each hydro-geologic unit is highly heterogeneous at the different scales studied.

Jan 1, 1993