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By C. Tom Blevins

LADIES AND GENTLEMEN : This presentation is to discuss production and roof control problems associated with directional lateral stresses in an in situ stress field and the approach that Inland Steel Coal Company made in trying to cope with them. Before proceeding, a brief description of the mine location, product, geology, restraints, and mine history is in order.

Jan 1, 1982

By Michael Karmis

This paper reviews the fundamental concepts involved in the development, application and validation of ground movement predic¬tion methods developed by Virginia Polytechnic Institute and State University (VPI&SU) over the past 12 years. Prediction techniques have included empirical or semi-empirical methods, such as the profile function, influence function and zone area methods, as well as numerical methods, based on a finite element formulation which utilizes field subsidence data. The former techniques have been integrated in the Surface Deformation Prediction System (SDPS) software package for personal computers, which allows for the calculation of any component of ground movement in any direction. Comparisons between measured and predicted subsidence and strain values are presented for a selection of case studies, which demonstrate the applicability, accuracy and regional validity of these methods for predicting surface deformations due to underground mining.

Jan 1, 1986

By Robert L. Wade

The two primary goals in underground coal mining are to improve safety and to lower mining costs per ton through increased productivity. However, as evidenced by the drastic decrease in. productivity since the enactment of the 1969 Coal Mine Health and Safety Act, (the Safety Act), these goals appear to be mutually exclusive. Millions of dollars have been spent in the res, arch and development of systems to solve this problem. Before the Safety Act, "productivity had experienced a 25-year history of continued increases ...? (Douglas, 1980). But since its enactment there have been dramatic decreases in productivity accompanied by phenomenal increases in mine costs. Labor trends, depletion of the more readily minable underground coal reserves and other factors have contributed to this situation, but the dominant factor is undoubtedly the Safety Act itself. To illustrate, prior to 1969 underground coal mine production was much greater than surface mine production but since then underground mine production has been declining at a rate greater than the overall growth rate of total coal production.

Jan 1, 1985

By P. R. G. Bak

The integration of interactive computer graphics technology with data analysis tools can assist in the evaluation of deposit models: the super- imposition of mine openings on complex geology can be quickly perceived using dynamic visualisation, colour-coding and transparency control while analysis functions assist in quantifying displayed information. To illustrate the functionality of such integration a research prototype system is presented which allows the interactive visualisation and evaluation of deposit models comprising both structural boundaries and the distribution of continuous properties.

Jan 1, 1992

By J. Fox, C. Allen, A. Greth, K. Kocsis

"It is the duty of the mine operator to ensure the mine environment is healthy and safe for the mine workers. For deep and hot underground mines, this requires maintaining adequate working temperatures by means of mitigating the heat load generated by strata, auto-compression, mining equipment, explosives, ground water, and human metabolism. The heat load is best reduced by minimizing the amount of heat transferred to the mine air from these sources and through the use of efficient ventilation with effective cooling systems. The heat emitted by mining equipment and vehicles contribute a significant proportion to the combined heat load of an underground mine. This is especially a problem for diesel equipment due to the fact that besides heat, a large amount of water vapor is produced, which increases the humidity in the production workings. Diesel engines have proven advantageous in recent history due to their high power output and reliability. However, as mines continue to become more mechanized and deeper the climatic problems introduced by elevated heat generation will continue to rise. With that, the issue of heat generated by diesel equipment must be addressed. The economic alternative for diesel engine equipment fleets in underground mines is the electric engine. Technological advances in battery technology, increased mechanical output and improved reliability have made the electric engine significantly more competitive in comparison to diesel engines. Because electric engines do not utilize internal combustion, the heat produced by them is significantly less than of the diesel engines. Battery powered mining equipment likewise eliminate diesel particulate matter (DPM) produced by diesel engines. Utilizing battery electric equipment in underground mines provides many advantages, such as: (a) reduced heat load, (b) healthier and safer environment for the mine workers, and (c) reduced mine operating costs due to lower ventilation requirements. This paper will highlight the health and cost benefits of using battery/electric fleets versus diesel fleets in deep and hot underground mines. The study analyzes simulations produced from thermodynamic ventilation models. Early simulations show significant cost reductions in terms of net present value (NPV) when comparing the air volume requirements for battery/electric equipment versus diesel powered equipment for the same production rate. INTRODUCTION The competitiveness of the world mineral market demands that mine operators continue to increase production and decrease costs as commodity prices fluctuate in often unplanned directions. This has forced underground mines to operate at deeper depths and to become more mechanized to remain competitive. Because of these changes, ventilation challenges have continued to increase as the mines combat an enlarged influx of contaminants such as heat and diesel particulate matter (DPM)."

Jan 1, 2018

By Robert L. Grayson

In small coal mining operations, little is done in controlling supply and material inventories and optimizing total inventory costs. Material Requirements Planning (MRP) is an efficient material control system which time-phases net material requirements based upon production plans, bills of material data, and inventory status records. Inventory levels and total inventory costs are optimized using a lot sizing technique in placing time-phased purchase orders. The MRP system has been applied in large manufacturing firms utilizing mainframe computers, but it can be adapted to micro-computers for inventory control. This paper presents an application designed to assist the coal mine manager in optimizing inventory costs.

Jan 1, 1985

By Richard L. Bullock

INTRODUCTION TO COAL MINE PRACTICES To illustrate the trends and the proportions of the various methods used to mine coal underground, Fig. 1 is useful. However, of all the underground coal mining practices in the US, room-and-pillar mining still accounts for 96.5%. This percentage is divided as follows: conventional, machine cut-33.0%; conventional, hand cut -1.7% : and continuous mining-61 .8%. As was stated in Sec. 1, Chap. 7, the term "development" means different things to a coal miner and a metal miner. Though some of the ideas and concepts presented in the first two chapters of this section are valid for all types of mines, they apply particularly to mines using noncoal methods. In coal mines (and many other mines using coal mining systems) development refers to that phase of the mining cycle which advances several entries through the virgin seam, forming pillars by cross- cutting between the parallel entries. Because in the past, coal seams (as well as seams of potash, trona, oil shales, gilsonite, salt, and some uranium) have been much more uniform in their thickness, continuity, and quality, and because they often cover large areas, it has been possible to develop the room-and-pillar mine completely from a preplanned, systematic approach with a minimum of surface drilling information. As the better coal seams of the midwest and east are being depleted (or eliminated because of high sulfur), seams of poor quality and continuity will have to be mined. Also, seams that are not nearly so well known at greater depth will have to be taken as well as some of the steeply pitching and folded seams of the west. The American coal miner is only now feeling the need to do a much more complete job of prospecting the geology of the coal seams than he has ever done before. This is the only way that the risk of unknown rock conditions can be minimized. In many ways, surprises in the rock or coal seams are much more of a disaster to the coal miner developing a room-and- pillar mine than to his metal mining counterpart. Be- cause of the multiple entries, the complex set of the Federal Coal Mine Health and Safety regulations, and the totally dedicated design of coal mining equipment, coal mining systems do not have the flexibility to easily overcome changes in the seams mined or the rocks around them. Thus, if a wide parting of rock shows up unexpectedly in the middle of a coal seam entry being milled away by a continuous miner, it will either have to slowly "chew" through it, convert to a conventional mining system, or stop that particular entry. Likewise, if suddenly the coal disappears completely and in its place are the remains of an old creek bed, the "want" or "wash out" as it's called will usually have to be mined right along with the coal, by the same methods and with the same soft rock equipment, or the entry will have to be abandoned. For reasons such as these, coal seams today should be drilled from the surface just as thoroughly as the ore bodies in metal mines. Having once determined a more precise location of where the coal seams are located and which are suitable for mining, the engineer must still take a systematic approach to planning the mine as completely as possible. The initial series of entries must be planned to be driven either from the side hill portal or from the bottom of the shaft or slope. In either case, they should usually intersect the area close to the midpoint of the mass to be mined.

Jan 1, 1982

By Donald C. Moore

Asamera Minerals Cannan Mine has been producing a 170 g gold/tonne (5 oz gold/ton) siliciaus flotation concentrate since July 1985. Flotation concentrate is shipped to a smelter for gold recovery. Numerous processes have been investigated to economically produce bullion on site. This paper describes the laboratory and pilot plant test results of a bacterial assisted oxidation of the refractory minerals. Economic comparisons with autoclaving and roasting processes are included.

Jan 1, 1989

By John S. Owens

The National Steel Pellet Project and the Butler Taconite Project are operated by The Hanna Mining Company in the vicinity of the towns of Keewatin and Nashwauk, on the western Mesabi Range. Production began in 1967, after seven years of exploratory and development diamond drilling and reconnaissance magnetic surveys, Previously, direct shipping hematitegoethite ores and gravity concentrates had been produced in the area from numerous open pits and several underground mines since the start of the century. Total shipments of these oxidized ores amounted to more than 200 million tons, but at the present time such reserves are nearly exhausted, and there are no mining operations in the Keewatin-Nashwauk area except at the two taconite projects. The locations of all of the present taconite operations on the Mesabi Range are shown in Figure 1, extending for a distance of about seventy miles from the Butler plant to the Dunka River area. The Butler and National plants have a combined rated capacity of 4.4 million tons of pellets. Their reserves cover a combined strike length of about eight miles on the Biwabik iron formation. All of the intervals between present taconite operations on the Mesabi are potential sources of additional magnetic taconite; in particular, exploration and economic studies have been carried out by Jones and Laughlin Steel Corporation in the Biwabik area between Aurora and Virginia, and by Pickands Mather and Company in the Hibbing area. However, west of the Henna and Butler holdings, it appears unlikely that magnetic taconite exists in commerical quantities at economic depths due to extensive oxidation of magnetite to hematite.

Jan 1, 1968

By H. Polat

Relatively large amounts of such hydrocarbons as fuel oils are often needed in flotation of low rank coals. The amount of oil can be decreased considerably by using surfactants as promotors. The reagents which are good candidates as surfactants to promote hydrophobicity can also act as emulsifying and wetting agents. Since the physical and chemical variables influence various sub-processes in different ways, their influence on the performance parameters is complex. The results of laboratory tests are presented to show that the dual role of reagents can be judiciously exploited to increase both the recovery and grade of clean coal. The mode and order of reagent addition is critical in enhancing their efficacy as flotation promotors. The results demonstrate the benefits of proper conditioning of the pulp prior to flotation.

Jan 1, 1997

By Guy T. Jr. McBride

World food production is not matching the exploding increase in world-population. Since arable land is limited, ways are being sought to increase yields by turning_ to fertilizer. Phosphate, an essential fertilizer ingredient, is undergoing a period of growth unparalleled in history. The United States is at once the world's largest producer of food and of phosphate rock. Both food and fertilizer output in the United States are being enlarged to meet the demands posed by the threatening world food crisis. New phosphate deposits are being developed in Florida and North Carolina to assure the United States' continued preeminence in this vital resource. Large fertilizer complexes are also being constructed with an eye to both domestic and foreign markets. The growth of the U. S. phosphate industry has been characterized by developing technology in the processing and distribution of phosphate raw materials. The trend from low analysis to high analysis materials accompanied by a change from a large number of small fertilizer plants oriented toward the marketplace to a fewer number of large plants located at the raw material source is illustrative. These changes in technology and distribution have also been important factors in the development of new mining areas in Florida, the Western States and North Carolina.

Jan 1, 1966

By Byron M. Jones

The use of computers in system analysis is well established. Analog computers have been used for this purpose since about 1940. As the power of digital computers increased and their cost decreased, much of the analysis formerly done by analog computers has been diverted to digital computers. The mathematical foundation for system analysis was laid between the years 1700 and 1900. In the 1930?s, telephone repeater amplifiers were designed using systems analysis techniques. From 1940 to 1960 systems were analyzed using either direct simulation or LaPlace transforms. Since 1960 analytical methods have been expanded to include linear vector space theory. All of these methods are being used to analyze the dynamic behavior of mining machinery.

Jan 1, 1974

By Robert H. Merrill

7.1-STABILITY OF SLOPES IN SOIL AND ROCK ROBERT H. MERRILL 7.1.1-DESIGN ANALYSIS APPROACHES The analyses of slopes in soil or rock can be made through application of soil- or rock-mechanics principles. In most cases, the material in the slope wall can easily be identified as either a soil or a rock. However, there will be instances where, because of unique characteristics, the soil may behave as a rock structure, or vice versa. By necessity, these unique cases must be identified through experience or critical observation by the engineer, because there are no definitive rules clearly establishing the differences. The most important step in a solution to a slope problem is to define it. Normally, once the problem is identified, a solution usually can be found or a reasonable estimate obtained. The design analysis of a slope wall implies an evaluation of the stresses or forces in the wall, and of the ability of the material in the wall to withstand them. Therefore, the factors influencing a design analysis can be divided into two categories: those which influence stresses, and those which influence the ability of the wall to withstand stress. For simplification, the latter is termed the strength of the soil or rock. Perhaps the basic difference between analyses for soils and those for rock is in the identification of the failure surface. Soils generally do not have an identifiable failure plane. However, some soil layers in a slope wall may have different strengths. A soil slope wall may consist of a thin layer of topsoil overlying a thick, uniform clay, or a topsoil over a gravel or other materials. Therefore, the soil generally does not have a potential plane of weakness that can be identified through observation. On the other hand, rocks normally contain planes of weakness in the form of fractures, faults, joints, bedding planes or other discontinuities weaker than the intact rock, which can be found through observation and/or tests upon rock samples. If the failure surface cannot be identified, the principles of soil mechanics should apply because, in soil mechanics, the failure surface usually is assumed. If it can be identified, then the principles of rock mechanics should apply. 7.1.2-ANALYSES OF STRESSES OR FORCES IN SLOPES All existing methods of soil-slope analysis are based upon interpetations of the Coulomb and Coulomb-Navier failure criteria, commonly termed the total-stress 2nd the effective-stress criteria (Sec. 6.1). The total-stress criterion may be illustrated by the diagram in Fig. 7-lA, which relates the total stress, S, to the cohesion, c: the normal stress, u, and the angle of internal friction, 9, by the expression

Jan 1, 1973

By William W. Magnus

The Eastern Magnesia Talc Company has always had the problem of adequate storage at its various mines and mills of not only crude ore and finished product but also material in process. An opportunity arose a couple of years ago with the decision to build a new mill at West Windsor, Vermont, (Figure 1) to come as close to providing adequate space for ore and the ground talc in the new plant as money and judgement would allow. Since our engineering staff did not have the time to design and engineer the new facility, an architectural firm with complete engineering staff was retained. Our original thought was to contract all phases of the construction and installation, however, and I think this is a most important point for any small firm such as ours, we found that with good supervision we, as the contractor, could do the job faster and at a lower cost than the construction firms that bid on the work. For some 50 odd years Italian talc has had a virtual monopoly in the body powder area of the cosmetic industry. Due to the purity, superior lubricity and whiteness, naturally occurring in the talc from Italy, no talc in the Western Hemisphere could capture any but a very small part of the market. When the Italian supply was cut off during World War II, the United States' largest consumer of this talc decided that it was time to develop a domestic source of a satisfactory replacement.

Jan 1, 1965

By R. E. Mason

Shotcrete has been used for approximately 20 years to facilitate tunnel excavation through poor ground. Early examples of such usage in North America include the recuperation of the Granduc Mines access tunnel in Northern British Columbia, and similar work performed in the Carley V. Porter and Big Walker Tunnels in the United States. Mining companies such as Craigmont Mines in B.C. and Hecla Mines have used shotcrete in their workings for the past ten years. Shotcrete is now a widely utilized fool in the mining and tunnel construction industries in North America, but the accumulated experience is too limited for many to fully appreciate the capability of shotcrete to control ground movements and to understand the limitations of this tool. It is common, for instance, to use shotcrete to "bridge the gap" between rock bolt-supported and steel-rib supported ground and to avoid the use of shotcrete in water-bearing ground. Shotcrete can, and has been, used economically and practically under most severe ground conditions.

Jan 1, 1976

By Dennis Arthur Fenton

The hydrodynamic bearing was first described by, Reynolds in 1886, and has since been widely applied in motors, engines, compressors, hydroelectric turbines, and other machinery. For various reasons, the hydrostatic bearing currently predominates in the large, horizontal rotating machinery field (e.g. grinding mills). However, the current industry trend towards increasing size and energy efficiency has resulted in renewed interest in the advantages of hydrodynamic bearings. These advantages include structural improvements, reduced bearing friction, improved bearing life, improved transient characteristics, and reduced lubricant pump size and power requirements. In particular, the higher energy efficiency results in substantial savings on large machines. This paper describes some aspects of the design of large hydrodynamic bearings based on thirty years, of experience in the design of such bearings on grinding mills ranging in journal size from 2.1 m to 6.4 m, see Table 1.

Jan 1, 1985

By H. O. Seigel

This is an introductory paper on a new method of prospecting for mineral deposits which has been developed by Scintrex Limited. The method, which we call Luminex, for luminescent mineral exploration, is based on time- resolved mineral luminescence created by an ultraviolet light source. It has the ability to detect and resolve a group of key minerals which are either ore minerals themselves, or more often, are accessory or pathfinder minerals for certain types of economic ore deposits. Fortunately, these minerals are commonly found at the earth's surface, even in areas of considerable weathering. The method extends the range of mineral deposits which are remotely detectable from the air to include those such as tungsten, tin, molybdenum, gold and bedded lead-zinc deposits and, is therefore, a natural supplement to our three classical methods of airborne geophysics.

Jan 1, 1983

By John F. Slonaker

This report is a review of current research being conducted in the United States which is intended to increase the utilization of coal ash. In order that this report be as timely as possible, the majority of information was obtained by direct comunication with the people listed in the references. Due to the magnitude of the flyash research program, some projects may be inadvertently omitted. Field research on flyash for use as an agricultural fertilizer is being monitored at Virginia Polytechnic Institute and State University.1 This research is directed at determining the plant nutrients that are available in flyash as well as the quantities of flyash that can be applied to agricultural soil without adversely affecting plant growth, Coal mine spoil and refuse bank reclamation with power plant flyash is being demonstrated by United States Bureau of Mines, Morgantown, West Virginia.2 Numerous highly visible coal refuse piles and strip mine spoil banks contribute to air, water, and land environmental problems. Revegetation of several experimental sites with flyash from bituminous coal-fired power plants was undertaken in West Virginia and Pennsylvania. Conventional farm equipment was used at some of the sites while large earthmovers were required at others. The flyash served as a neutralizing agent, dilutent, and soil amendment to provide some nutrients which enhanced vegetation of the barren areas, Estimated cost of reclamation by this method is $300.00 per acre of previously leveled area. This figure can vary considerably depending upon the topography of the site, haul distance, quality of the soil and quality of flyash.

Jan 1, 1974

By J. E. Lonergan

The in-pit placement of crushing and conveying equipment results in a flattening of the pit slope of a multiple-bench open pit mine. To maximize the economic benefit of lower haulage costs associated with in-pit conveying, one must minimize the cost of the flatter slope which is expressed in terms of additional stripping or tied up ore. A computer program that compares the tonnage aspects of various conveyor layouts will be discussed.

Jan 1, 1985

By D. P. Bryan

The identification and-develop¬ment of new construction aggregate resources, the most common mineral mined, is an essential need in this country's growing urban areas. In developing an aggregate exploration program, a thorough geological identification of all potential aggregate resources in an area is still of primary importance but other factors have also to be considered. These include physical properties, end product application, transportation and mining costs, and local government regulations including zoning. The present major aggregate producers are most likely to develop these future resources and are in the best position to initiate comprehensive exploration programs.

Jan 1, 1987