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By David Burgess

The paper describes experiments at the Somerset Mine, Colorado, under a cooperative agreement between U.S. Steel and the U.S. Bureau of Mines. A test was made of the tube bundle method of mine air sampling which was developed for European longwall mines; some 300,000 running feet of tubing provided continuous monitoring at 39 locations. Carbon monoxide concentrations were obtained with standard deviations of less than 1 ppm and oxygen concentrations with standard deviations of less than 0.20 percent. A base level of CO index (ppm CO evolved/pct 02 removed)) was determined to be 0-20 through most of the passageways of the mine. However, in one working section where the coal was initially hot (about 180°F within a pillar) the CO index was demonstrably higher, >20 trending upward to about 60 when smoke appeared and the section was sealed. The data are discussed in terms of laboratory experiments on CO evolution from coals.

Jan 1, 1975

By Shankar S. Hegde

In many areas of the United States much of the most readily minable coal is nearing depletion, while at the same time, increased national attention is being given to coal as a major alternate energy source. If some of the thinner, more erratic, deeper and lower quality coals, which comprise the great bulk of U.S. resources, are to be mined efficiently and economically, greater attention must be devoted to careful planning of mines and to preparation facilities. One of the cornerstones to careful and successful mine planning is precise knowledge of coal thickness and areal distribution, roof and floor quality, and seam quality. Data on which this knowledge is based are obtained from various borehole techniques and, in some cases, seismic methods. Despite the many technical innovations that have been made in acquiring subsurface data, little attention has been given to the problem of systematic storage and retrieval procedures of the data and assembling them in a form that can be used for various computer mapping programs now available. (See Bilter and Martin, 1977; Bryant and Zobrist, 1977 and Farrell and Wherry, 1978). The purpose of this paper is to describe a series of user oriented programs developed over the past five years which are specifically designed for precise logging of rock core, accurate storage and retrieval of this data, correlation of seams between logs, tagging seams, computer assisted data posting of maps and preparing maps and profile sections for report illustrations. The entire system stresses increased precision and speed for a series of operations which are now largely manual, time consuming and prone to error.

Jan 1, 1980

By J.N. Kohmuench

Teeter-bed (i.e., hindered-bed) separators are used throughout the mineral processing industry for both classification and density separation. The high capacity and sizing characteristics of these units make them ideal for feed preparation prior to coarse flotation (+0.100 mm) circuits. Teeter-bed separators are typically easy to control with two basic operating parameters, including fluidization water rate and bed level. However, data show that these two parameters greatly interact with one another. Given this finding, a high-level automatic control scheme was developed and implemented on a full-scale separator. In addition, dialogue with plant operators has led to several simple changes to an already established design that improves operational and maintenance characteristics.

Jan 1, 2010

By F. A. Renninger

The mineral aggregate industry is the world's largest mining and processing endeavor, yet it is graced with little of the romance or public awareness that accompanies mention of gold, silver, iron, copper, uranium, or aluminum mining efforts. Much of this reaction is undoubtedly due to the fact that the uses to which crushed stone and sand and gravel are normally put are not fully recognized or appreciated by the general public. Few individuals ever have occasion to purchase mineral aggregates for anything other than use for decorative shrubbery beds or walkways. They may, however, buy ready-mix concrete for a new patio, bituminous concrete for a new driveway, concrete blocks, or other building materials for a new room and never realize that the primary ingredients of their purchases are either direct or indirect products of the mineral aggregate industry. The average person driving past an operating crushed stone quarry or an active sand and gravel pit rarely realizes the economic impact the industry, represented by that operation, exercises on the general economy. He is not aware, nor does he really care, that elements of the modern comfortable environment to which he has grown accustomed rely to a great extent on the products of the crushed stone and sand and gravel industries Iron and steel, glass, cement, agriculture, and highway and building construction are but a few of the major industries to whom the products of the mineral aggregate industry are basic. Without these industries or without the stone, sand, and gravel basic to them, most of the major elements of our modern day civilization would be non-existent.

Jan 1, 1968

By C. L. Karr

Researchers at the University of Alabama are investigating artificial intelligence based computer models of mineral processing systems. Two approaches have been found to be particularly effective in developing data-driven computer models. The first approach employs neural networks which are computational paradigms based on the mechanics of the human brain. They are able to extract the basic relationships between input and output variables from large data sets. The second approach combines fuzzy mathematics with genetic algorithms to produce an adaptive modeling system. Fuzzy mathematics provide computers with the capability of manipulating abstract concepts like those which humans use so effectively in decision making. Genetic algorithms are search algorithms that mimic evolutionary processes apparent in nature. Together, these two techniques can be used to produce an effective modeling system. In this paper, the two approaches to modeling are compared and contrasted with respect to accuracy and computational time while used to model three mineral processing systems: (1) a grinding circuit, (2) a hydrocyclone separator, and (3) a flotation circuit.

Jan 1, 1997

By K. Zabrusky

Estimation of high grade epithermal vein deposits can present challenges in correctly representing the continuity of grade within an undulating structure. One solution to this problem is to use dynamic anisotropy to follow local variations in the strike and dip of veins. Dynamic anisotropy (D.A.) allows the search parameters to change block by block throughout the model to account for the local variations. Presented here is a study of a vein that changes orientation down-dip. A traditional resource estimate using one search ellipse orientation was performed. The resulting estimated grades did not accurately reflect those of the sample data. Using a search ellipse with an average value for the two distinct dips caused the grade estimation to be less representative than desired. Rather than performing domain-based analysis with different search ellipses, the issue was corrected by using Datamine Studio 3?s D.A. function. The 3D vein trend was used to estimate the dip and dip direction of the vein in each block. The resulting D.A.-estimated model follows the two dip trends of the vein. This software makes a previously tedious task faster, and allows for more accurate estimations.

Feb 27, 2013

By G. K. Wilson

This paper will discuss some of the more important aspects to be considered when selecting pumps for mill discharge, cyclone feed or other severe-duty applications Included will be the selection of the pump based on such factors as particle size, particle distribution, head, flow, temperature and pH Other specifics to be covered: The relationship of impeller speed, head and wear factors as they affect pump performance and wear life; the importance of selecting a pump whose performance curve best suits the application; and how the addition of service factors applied to the actual operating conditions can lead to severe operational problems such as premature wear, pump running out on curve, and exceeding horse power limitations.

Jan 1, 1996

By Arthur S. Cornford

According to Arbiter (Reference 1), the ball mill was invented by Brückner in Germany in 1876 and was first used in the United States on ores about 1905. The basic concept was a simple rotating cylindrical drum in which the tumbling action of the charge of material and grinding media resulted in size reduction of the material. Despite the very low mechanical efficiency of this method a number of factors have caused the tumbling mill to remain, by far, the most widely used piece of equipment for mineral grinding. The principal factors influencing this situation have been simplicity of design, ease of manufacture, ready adaptability to familiar material handling layouts and the absence of practical alternatives acceptable to the industry. In the early mills, the material was ground in batches, the mills being charged and discharged through doors in the shell. The shell was supported by means of solid trunnion shafts resting in plain bearings and the drive was accomplished through one of these shafts. In some later batch mills, the mill shell was supported on rollers which were also used to drive the mill. At an early stage, continuous operation was made possible by feeding and discharging the mill through hollow trunnions, the method still in most widespread use. The mechanical and structural design of the early mills was not an onerous engineering task. Norse sense and good practical knowledge were key qualifications. The mill shells had to be heavy enough to withstand the physical abuse they would receive in the field and the bearings had to have low enough unit pressures and sufficient wear retol to ensure several months of operation before the need for replacement occurred. When these requirements were satisfied, stresses developed in the equipment during operation were insignificant and the majority of structural failures were probably due to the use of inferior materials in manufacture. Over the years, the ever present demand for increased productivity has resulted in a steady Increase in the size of units of production equipment, including grinding mills. Arguments have been presented elsewhere, for and against the Idea of a high throughput single line grinding operation as opposed

Jan 1, 1972

By R. Heiser, J. Vendetti, B. P. Connor, E. J. Haas

"DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health. ABSTRACT Health and safety indicators help mine sites predict the likelihood of an event, advance initiatives to control risks, and track progress. Although useful to encourage organizations to work together, executing such risk assessments comes with challenges. This paper focuses on one trona mine’s experience in the development and implementation of a field level risk assessment program to help its entire organization understand and manage risk to an acceptable level. Through a transformational process of ongoing support and communication, Solvay Green River fostered a culture of trust and safety grounded in risk assessment, safety interactions, and hazard correction. The application of consistent risk assessment (RA) tools was critical to create a participatory workforce that not only talks about safety, but actively identifies energies that contribute to hazards and potential incidents. In this paper, reflecting on the mine’s process of RA implementation provides examples of likely barriers that sites may encounter when trying to document and manage risks. As discussed, consistent efforts to establish a participatory risk management program are worth the initial struggle to ultimately reduce incidents. INTRODUCTION Work-related health and safety (H&S) incidents often account for lost days on the job, contributing to organizational/financial and personal/social burdens [1-2]. Accompanying research demonstrates that risk and ambiguity around risk contribute to almost every decision that individuals make throughout the day [3-4]. In response, understanding individual attitudes toward risk has been unquestionably linked to predicting H&S behavior [5]. Although an obvious need exists to identify more comprehensive methods to assess and mitigate potential hazards, some argue that risk management is not given adequate attention in occupational H&S [6]. Additionally, research suggests that a current lack of knowledge, skills, and motivation are primary barriers to mitigating workplace risks [3-6]. Therefore, enhancing knowledge and awareness around risk-based decisions, including individuals’ abilities to understand, measure, and assign levels of risk to determine an appropriate response, is increasingly important in hazardous environments to predict and prevent incidents. This paper focuses on tailored approaches to field level risk assessment (FLRA), measurement, and common barriers to participating in such activities. The authors use a trona mine in Green River, Wyoming, as a case study to illustrate how the organization overcame widespread and site-specific challenges to implement a proactive risk management program. By discussing the mine’s tailored FLRA program, this case study contributes to the literature by first, providing examples of critical components that need to be in place to ensure successful risk management and second, context for continuous quality improvement that can foster a higher level of trust and empowerment on site."

Jan 1, 2017

By S. Que

Local community acceptance is a key aspect of planning and managing mining projects, whether through sustainability assessment and reporting or corporate social responsibility programs. However, there has been very little research to understand the determinants of community acceptance. This paper seeks to identify key mine characteristics and demographic factors that influence individual acceptance of mining projects. Six demographic factors and 16 mine characteristics were selected based on literature review. Four of the six demographics factors were confirmed to be significantly (p < 0.05) correlated with people?s attitude of the importance of the mine characteristics. All sixteen mine characteristics are identified as important factors. The most important mining factors are Job opportunities, water shortage or pollution, air pollution and land pollution. Both the mining and control groups have same opinion of 12 mining characteristics and differ on four (infrastructure improvement, labor shortage for other businesses, noise pollution, and mine life). During design and management of mines, this data can be used as a reference. This result will facilitate better choice experiment (survey) design for discrete choice modeling. Such discrete choice models can provide a viable framework for data-driven community engagement and sustainable mine management.

Feb 23, 2014

By Harrison A. Schmitt

During .the past five decades or so we have passed from a time when it was difficult to point to a mine or an ore body and verify that it had been discovered by geological methods, through the. Twenties when the common saying was, "Who ever heard of a mine found by a geologist?", to recent decades when hundreds of mines and ore bodies are acknowledged geological discoveries and the above query can be ignored. Recently, however, the application of mining geology appears to have been downgraded, or so it seems to me. Basic geology in mining has been cheapened and glossed over in favor of geophysics and outcrop sampling, even though the latter is merely one technique of mining geology and, to some extent anyhow, has been used for a. long time. (Locke, 3, pp 81-87). Geophysics by itself and in conjunction with geology has had success in certain geological provinces, but limited attainment in mountainous terrane except in those few cases where strongly magnetic minerals are associated with ore. Nevertheless, in the Cordillera .many experimental techniques are offered as proved ones. This is not an intent to try to depreciate honest geo- physics. Continued experimentation and use of it is approved by all, but at the same time it is foolhardy to throw mining geology overboard, Generally both approaches should be considered and usually, at first anyhow, geology is the most direct one.

Jan 1, 1960

23.1-SOURCE, POWER-SYSTEM ELEMENTS A. J. T HUM Basic considerations in providing power for mine production and collateral operations are: 1. Mining operations of any size normally use electric motors for driving all equipment except mobile service units. 2. The electricity for power may be purchased or self-generated, depending on the location, size and specific operating circumstances of the individual property. 3. The major elements of the power system will be the source, either an incoming transmission line from a utility in the case of purchased power or the power plant if self-generated. Energy for the power plant may be water, hydrocarbon fuels, waste heat or nuclear, which will govern the type of prime mover selected. 4. The electricity normally is generated in the form of alternating current and must be distributed to the points of usage. This usually requires a primary substation for transformation to suitable voltages and secondary substations at points of usage throughout the operations, The power is delivered from the primary to the secondary substations over transmission lines or cables, depending on distances, voltages and local conditions. 5. At the points of use, there will be starting and protective devices for each motor. In some instances, direct current will be needed and rectifiers of various types can be used to provide it. 6. The entire electrical system requires suitable switching and protective devices to prevent damage to the equipment in case of power failues or faults; also, in most cases, sufficient metering to establish the demand and amount of electrical energy consumed. 23.2-PURCHASED POWER A. J. THULI 1. Where public-utility or government-generated power is available, it usually is advantageous for the mine owner to purchase rather than generate. Purchased power generally will be cheaper and more reliable than operating a small generating plant except in some cases where waste heat is available as the source of energy and can be used to supply all or a portion of the power requirements. 2. If it is decided to purchase power, the owner usually must participate in the cost of constructing the connecting line from the closest existing utility line to his point of usage. If the connected load is less than 1,000 lip, it probably is best to let the utility provide the primary substation. For larger connected loads the owner can obtain a more favorable "primary voltage" rate if he provides the primary substation to receive the incoming power and transform it to the distributing and usage voltages. 3. The cost of purchased power usually is made up of a demand charge, deter¬mined by the maximum amount of power the customer takes during any 15-min period throughout a month, and a graduated energy charge for the kilowatt-hours consumed-that is, so much for the first block of energy based on the demand,

Jan 1, 1973

By D. Hulse

"The science of “optimal economic pit design” has been highly refined in the last decades. Even with the proliferation of optimizing and heuristic algorithms exploiting ever faster computers, the most common input is a single block model and a single set of cost assumptions, each of which is an estimate and prone to errors. An analysis of price assumptions produces a suite of nested economic shells, each with its own quantities of ore, waste, grade, and profit, but due to irregularities in the mineralized body, the growth of these shells can be erratic. To control the impact of the errors of the model and cost assumptions when choosing the pit shell for design, graphs of pit shells characteristics, such as stripping ratio, cost per unit of product and profit/ton, can be analyzed to consider points with higher stability, or robust pits. Selection of robust shells for a pit limit and for push backs can help to understand the impact to profit and risk. The robust shells also guide the preferred solution sets for final pit and cutoff optimization. INTRODUCTION “An open pit mining operation can be viewed as a process by which the open surface of a mine is continuously deformed. The planning of a mining program involves the design of the final shape of this open surface.” Optimum Design of Open-Pit Mines, Lerchs, H. and Grossmann, I. Transactions C.I.M. Volume LXVIII 1965. Traditionally an analysis of economic pit shells and sensitivity was performed by varying the input metal price. This was done with both floating cone algorithms as well as early versions of the Lerchs-Grossmann (L-G) algorithm. This gave an indication of the pit sensitivity to price but since other variables also change, some with metal price (perhaps steel and equipment), and some independently (fuel and tires) the understanding of these different pits was restricted. In addition, a run of the program could take hours, making a detailed analysis of small changes unwieldy. The L-G algorithm was programmed by a variety of people and sold as part of commercial mining packages, however it was first and most successfully commercialized by Jeff Whittle in 1984. When Whittle’s 3-D™ was expanded to 4-D the parameterization of the economic inputs was considered and the ability to run a suite of “pit shells” became automatic. The competing NPV Scheduler™ program sold by DataMine™ offers similar pit shell analysis capabilities."

Jan 1, 2018

By Jie Li, Longxiang Li, Wenbing Guo, Gaobo Zhao, Yuhang Hu

Surface subsidence caused by underground longwall mining is a very complicated process in time and space, influencing building and structures on the surface of the mining area, including houses, pipelines, and highway. The field monitoring data of surface subsidence are essential for protecting them. This study investigated the dynamic and residual subsidence characteristics of both the surface and the highway over a 730-day monitoring period on a longwall panel. Three monitoring lines (Lines 1–3) were established to monitor the subsidence process, and three stages were identified: initial stage of surface subsidence, active period of surface subsidence, and residual subsidence deformation stage. The maximum subsidence value on the highway (1,786 mm) was smaller than that on the surface (2,094 mm), and the maximum subsidence velocity on the highway (41.7–50.8 mm/day) was also lower than that on the surface (66.7 mm/day). During the residual subsidence deformation stage, both the surface and highway subsidence velocities decreased to below 0.6 mm/day. Furthermore, differences in subsidence characteristics between the surface and the highway were analyzed, with the subsidence value on the highway always being less than that on the surface, while the subsidence velocity during the residual deformation stage was not always lower. This could be attributed to the influence of dynamic loads from vehicles, which could induce additional residual subsidence on the highway. Further investigation into this phenomenon will be conducted in future research.

Jul 1, 2023

By A. J. Kwitowski

Remote control for mining machines ordinarily means the operator is not seated on the machine, but is located within direct view of the machine and work area Thus, remote control operators are exposed to the hazards of roof/rib falls and dust/methane explosions. The U.S. Bureau of Mines has developed a method to disassociate remote operators from these hazards. Off-board, computer-based "tele-operational" systems are utilized that station the operators one-hundred meters or more distant from the working faces. Details are provided for tele-operated systems for thin-seam extraction and haulage equipment in highwall and deep, room-and-pillar coal mines.

Jan 1, 1992

By Meghan M. Murphy, Derek Penrice

The Downtown Rail Extension (DTX) is principal element of the planned second phase of the Transbay Joint Powers Authority’s (TJPA) Transbay Program. When complete, this regionally critical project will connect Caltrain’s regional rail system and the California High-Speed Rail Authority’s statewide system to the Salesforce Transit Center in downtown San Francisco via a 1.3-mile tunnel. Studied since the 1970s, the DTX has now received environmental clearance, and key stakeholders are aligned on the project’s configuration and its expedited delivery. This paper describes efforts to optimize the DTX configuration and develop an informed project delivery strategy that incorporates construction industry feedback on project phasing, contract packaging, and procurement methods that accomplish the project’s budget goals.

Jun 13, 2021

By Sarah Wilson, John Kaplin

Plans are underway to extend commuter rail service underground into downtown San Francisco. The Salesforce Transit Center (STC) was completed in 2018 and will serve as a new transit hub, including a commuter rail station after two future connecting tunnel segments are completed. The northern segment, known as the Caltrain Downtown Extension (DTX), which will extend the rail line from its current terminus at 4th and King Streets to the STC, is currently in Preliminary Engineering. The southern segment, the subject of this paper, is a 1.6-mile tunnel known as the Pennsylvania Avenue Extension (PAX), which is currently in the pre-environmental planning stage, with alternative alignments under evaluation including single bore versus twin bore options. This paper discusses project challenges, including highly variable tunneling conditions in soil and rock, a congested urban project site with limited space for construction staging, alignment crossings of large existing buried infrastructure, and complicated interfaces with future and existing rail operations.

Dec 1, 2022

By J. A. Boyle

In the Frick District of U, So Steel Corporation, we have had more than 37 years of experience in the use of multiple-fan ventilation systems, in our coal mines. In our Colonial field, with a long belt installation, we have mined 85 million tons of coal with the use of the multiple fan system of ventilation. In our Palmer field, with the use of the same arrangement, we have mined 90 million tons of coal--a total of 175 million tons without one accident attributable to improper mine ventilation. The same system, fundamentally, has been installed in our expanding Robena operations and at its present stage of development we are using eight fans to ventilate this area. To date we have mined 55 million tons of coal with very encouraging results and again without any accidents attributable to ventilation.

Jan 1, 1961

By R. K. Mehta

An electrochemical coal oxidation model involving heterogeneous kinetics is presented. This model was tested by collecting current transient data on three coals assaying different ash content under varying operating conditions such as particle size, temperature, and % solids. In all cases, the model fitted the data very satisfactorily. Three intrinsic rate constants, namely mass transfer coefficient of Fe(II) Ions diffusing from solution to the anode (kma), mass transfer coefficient of Fe(II) Ions diffusing from solution to the coal surface (kmc), and chemical rate constant for coal oxidation with respect to Fe(III) at coal surface (k), were calculated. It was interesting to note that in this system, the mass transfer at anode was as important as the chemical reaction at the coal surface. The validity of this model was further demonstrated through a comparison of the activation energy of coal oxidation: firstly, by utilizing calculated chemical rate constant and assuming Arrhenius&apos; type of relationship: secondly, by utilizing conventional approach using limiting current values. The comparison revealed that agreement was quite close. This kinetic analysis is useful because such a model can be used in predicting the intrinsic rate constants so that the relative importance of mass transport can be rationally analyzed.

Jan 1, 1991

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