Search Documents

When I wrote the Railroad portion of "Mining Engineering" magazines 94 Powder River Basin (PRB) Coal Article I described to you some definite destinations the Railroads had in mind. As with many destinations, the ones I wrote of turned out to be merely stops on the way to places that we have yet to reach. Somewhere along the way we discovered that making it better is a continuous process not just something that you can do in phases I, II, III, & IV. We always knew this I suspect, but perhaps not at the awareness level that exists in RR environments in 1997. The purpose of this article is to update the 94 article, which I could do very quickly. Everything I told you we were going to do in 94 is done, end of story! But in addition to making it a very short article it would not be telling you the things RR has done beyond what we were planning in 94 and for the future.

Jan 1, 1998

By C. Zhou, B. Whisner, J. Carr

Proximity Detection Systems (PDSs) are used in the mining industry for protecting mine workers from striking, pinning, and crushing injuries when they work in close proximity to heavy machines such as continuous mining machines (CMMs). Currently all Mine Safety and Health Administration (MSHA) approved PDSs are magnetic field based systems which can be influenced by the presence of wire mesh that is commonly used for supporting roof and ribs in underground coal m ines. In this paper, researchers at the National Institute for Occupational Safety and Health (NIOSH) characterize the influence of the mesh on the performance of magnetic PDSs by measuring the magnetic field difference around a CMM caused by the presence of the mesh. The results show that the magnetic fields are generally enhanced by the mesh which causes the PDS detection zones to be increased correspondingly. It was discovered that the fields around the joints of two mesh sections have the greatest enhancement and thus deserve more attention. In addition, it is found that the presence of mesh can also cause a variation in the generator current. The influence of mesh is characterized by the change in the generator current with respect to the distance between the generator and the mesh. It was found that the generator current change caused by the mesh can be significant (on the order of ten) when the mesh is extremely close to the generator (e.g, less than 1 cm) and is negligible when mesh is relatively far (greater than 0.15 m). The findings in this paper can be used to develop guidelines and best practices to mitigate the influence of mesh on PDSs. INTRODUCTION The Mine Safety and Health Administration (MSHA) requires operators of underground coal mines to equip place-changing continuous mining machines (CMMs) with proximity detection systems (PDSs) to protect mine workers from striking, pinning and crushing injuries when they work around these heavy machines. Although a variety of technologies can be implemented for proximity detection, the magnetic-field-based PDS that was originally developed at the National Institute for Occupational Safety and Health (NIOSH) has shown great effectiveness in challenging mining environments and currently all MSHA-approved PDSs are magnetic-field-based systems. As shown in Figure 1, a magnetic PDS typically includes two major components----the magnetic field generator and the Miner Wearable Component (MWC). Magnetic fields are generated by injecting a high electric current into a ferrite-rod antenna sealed in the generator. The magnetic field strength detected by an MWC varies with the distance between the MWC and the generator. In a typical PDS, multiple generators are mounted on different locations of the machine. The relative location/zone of an MWC is determined based on the field strengths from different generators picked by the MWC. Ideally, for a PDS to work properly in the underground, the magnetic fields generated by the different generators should be stable and not vary with the environment, as the system would interpret any variation of the magnetic field as a result of the distance change between the machine and the miner wearing the MWC. In reality, however, this is not always the case since magnetic fields can be altered by a number of environmental factors such as the presence of steel wire mesh that has been widely used in underground coal mines for supporting roof and ribs In this paper, the influence of mesh on the PDS performance is investigated and the magnetic field change caused by the mesh is measured.

Jan 1, 2019

By Mark E. Gershon

The development of long term plans and schedules for strip mines now faces many companies, especially those developing large properties in the West. The rule of mining the lowest strip ratios first, while delaying equipment acquisitions and recouping investment the fastest, creates the situation where stripping ratios are too high in the latter years of mining operations. A program concept taking life of mine return on investment into account is developed in this paper to optimize mine scheduling and equipment acquisition. In addition, quality considerations (heat content, ash, sulfur, washability) can be considered by including the appropriate blending constraints to meet contract requirements.

Jan 1, 1983

By G. R. Erdman

The industrial mineral filler plant of the Gouverneur Tale Company is equipped with a good dust collection system installed long before the recent popularization of environmental pollution. Credit for this fact is due to the foresight of Mr. R. S. McClellan, Project Manager and subsequent Vice President and General Manager of Gouverneur Talc, who recently retired as Vice President Engineering of the parent organization, the R. T. Vanderbilt Company. Also instrumental in the early stages of plant operation and the solution of start-up problems was J. A. Gustin who is now an engineering consultant located in Martinsville, Va. Credit is most certainly due to the late R. T. Vanderbilt, the company's founder, who favored and approved the investment in the necessary facilities that were far ahead of all competitors in the industry at that time.

Jan 1, 1972

By A. E. Ketler

Optical smoke monitoring fills an important gap in ventilation and fire safety: namely monitoring of smoky, low temperature fires where little CO and heat are generated. Smoke monitoring also avoids the nuisance alarms due to diesel exhaust, battery chargers, blasting and welding. The smoke optical density (OD) fire alarm standard specified by MSHA presents an opportunity for improved safety. Experience of actual mine usage of the SmokeBoss*100 is reviewed, with particular regard to effectivity, maintenance and cost.

Jan 1, 1995

By Gerald Pinter, David Nitsche, Márton Bredács, Markus Haager, Andreas Frank

"The reliable prediction of service lifetime of tunnel constructions is of essential technical and economic interest. Polymers used for tunnel liners have to fulfill the requirement of 100 years lifetime. However, today no reliably proven test method is available which confirms such long lifetimes. The current paper introduces a recently started research project which focuses on lifetime prediction of highly flexible, very low density polyethylene (VLDPE) for tunnel geomembranes. Different PE grades in combination with different antioxidant packages are conditioned at elevated temperatures and immersed in different media. Initial results confirmed significant material aging of unstabilized resins already after exposure of up to 34 weeks, at least at the highest exposure temperature of 80 °C. To consider application relevant material properties the material characterization was done by means of tensile tests and dynamic oxidation induction temperature tests. High pressure liquid chromatography was used for further investigation of antioxidant consumption kinetics. 1. INTRODUCTION For a reliable service of modern tunnel constructions a sustainable proofing against water infiltration is essential for the lifetime of the structure. Geomembranes made of polymeric materials have been used successfully for tunnel lining since several decades. Whereas previous geomembranes usually were made of plasticized polyvinylchloride (PVC-P), due to several technical advantages today very low density polyethylene (VLDPE) has become a more and more popular material for such applications. For modern geomembranes, current guidelines expect minimum lifetimes of at least 100 years (ÖBV-Richtlinie 2012). In contrast to this requirement it must be considered that today no test methodology is available which reliably confirms such long lifetimes of polymeric materials."

Jan 1, 2016

By Jozef Stachulak

Prof. H. Bystron: "An Application of the First Law of Thermodynamics to Winter Dry Air Flow in Mr. Stachulak's Mine Model". [ ]

Jan 1, 1980

By B. Morris

This presentation will describe the process by which the Quebrada Blanca (QB) copper project in northern Chile was financed. It will also show how a relatively junior mining company addressed the problems created by its inability to provide its share of the equity funding and the guarantees required by the project lenders. QB is located in the semi-arid Andean highlands of northern Chile, 170 kilometres southeast of the port of Iquique and 30 kilometres west of the border with Bolivia, at an altitude of about 4,300 metres (14,000 feet). Figure 1 depicts the project's location. The QB orebody is a secondarily enriched porphyry copper deposit containing reserves of 85 million metric tons grading 1.3 percent copper. Underlying the enriched zone is a significant primary ore zone containing several hundred million metric tons grading about 0.5 percent copper. In the late seventies and early eighties Falconbridge and its affiliates spent $20-30 million dollars exploring the deposit and conducting feasibility studies. For a variety of reasons they decided not to develop the property which was returned to its owners, Empresa Nacional de Mineria (ENAMI), which is a Chilean state mining corporation. In 1988 ENAMI announced its intention to privatize the property through a public bidding procedure.

Jan 1, 1993

By John Bley

White Pine Copper Company operates a mine in the Upper Peninsula of Michigan using a modified room-and-pillar system for extracting ore.1 Mine production averages 15, 500 tons per day. The terrain is predominantly level and the depth of cover varies from 500 to 800 feet over the present workings with depth increasing as mining progresses down the dip. The deposit is situated on a low angle plunging, anticlinal structure composed of sedimentary beds. Local terminology for the stratigraphic units which contain the ore horizons, named in ascending order, is as follows: lower sandstone, parting shale, upper sandstone and upper shale. The ore zones of copper enrichment are, contained in the parting and upper shales. The parting shale will vary; from 6. 5 to 9.0 feet thick; the upper sandstone from 2 to 10 feet; and the upper shale from 1. 5 to 6. 5 feet. Two variation of the room-and-pillar system are used to extract the ore depending on grade and local ground conditions. One system is called the parting shale method and recovers the parting shale only. This system requires a mining height of 8 1/2 feet to accommodate large-scale, high-capacity equipment and this working height is obtained by removing approximately 1 to 2 feet of the barren lower sandstone with the ore. Under the second system, locally termed full column, the mining height is about 14-1/2 feet and this system removes the parting shale, the upper sandstone and the lower mineralized zone, approximately 1-1/2 feet, of the upper shale at which point it is possible to maintain a competent back (Fig. 1).1

Jan 1, 1964

By L. Blain

In practice, geochemical analyses can be grouped in two broad categories according to their aim. Those that seek to determine the exact chemical composition of geological materials fall under the heading of assays, whereas applied geochemistry concerns itself with the detection of anomaly contrasts. Recent trends have blurred the distinction between both approaches for many users, as methods that were traditionally used for assays are being adopted in applied geochemistry and assays make increasing use of instrumental techniques. Nevertheless. it is important to keep a clear distinction between the two types of analyses because it has immediate practical consequences, cost is the most obvious, as well as fundamental implications. In the broadest terms, the goal of geochemistry is to strike an optimal balance between throughput and accuracy, at the lowest reasonable cost, while assays strive for accuracy. Traditionally, complete silicate analysis has been the concern of assayers whereas exploration geochemists have been more interested in base metal analyses where acid extractions of the elements, without dissolution of the silicate matrix, has been the norm. This kind of distinction is less realistic now, especially with the growth in lithogeochemical studies, and some overlap in methodology is unavoidable. However, where such overlaps occur the distinction remains in the emphasis of the work. A commonly used example is that although HF acid preparations are used by both, the emphasis in applied geochemistry is on sample throughput and batch analysis, whereas assayers are more concerned with the range of elements to be determined (Thompson and Walsh, 1983).

Jan 1, 1993

By R. H. Smith

The total energy demand in the United States increased about 4 per cent annually during the 1960's 1 and is expected to increase at the same rate during this decade. Z Fuel oil growth in the 1960's was only Z per cent per year until 1968, but it increased to 8 per cent in 1969 and 11 per cent in 1970. Fuel oil demand is expected to grow at a 6 per cent rate through the 1970's. Part of this rapid increase in demand has been caused by restrictions placed on the sulfur content of fuels. High sulfur coal can no longer be burned in many parts of the country and has been replaced by low sulfur fuel oil. An insufficient supply of natural gas has also contributed to fuel oil demand. Air pollution regulations have not only caused an increase in fuel oil consumption, but they have also caused a reduction of sulfur content in residual fuel oils. Current regulations call for 1 per cent maximum sulfur content fuels over much of the country. Sulfur contents of fuels are limited to 0. 3 per cent in certain areas on the east and west coasts. Sulfur in residual fuel oils from high sulfur imported crude oil is reduced to 1 per cent currently. However, sulfur reduction to 0. 3 per cent is difficult and expensive.4 As a result, refiners may be hard pressed to supply the market for low sulfur fuel oil. The oil shale deposits in Colorado and Wyoming potentially are a huge source of low sulfur fuel oil. It will be shown that the low sulfur content and more importantly the sulfur

Jan 1, 1972

By A. J. Dudzik

In 2006 Arch Materials initiated the development of an underground limestone mining complex. The decision to proceed with the project was the end result of several years of market research and geological reconnaissance. The scope of the project included the construction of two declines to the mining horizons located approximately 900 feet below the surface, the means and methods of this phase will be the primary focus of this discussion. The design, fabrication and erection of a state of the art crushing and screening processing plant which when completed will have the primary crushing located on the mine level allowing uniformly sized material to be brought to the surface by means of a highly efficient conveyor system and a surface portion of the plant where material would be additionally processed, screened and stockpiled into specific product types. Also included in the scope of the project is the construction of offices, warehouse and shop facilities necessary to support the operations, commercial sales and distribution of the finished products.

Jan 1, 2010

By A. B. Cortes

This research work discusses the development of a two-dimensional model that represents the flow that occurs in the inlet section of hydrocyclones. The governing equations are the two-dimensional, unsteady, incompressible Navier-Stokes equations in cylindrical polar coordinates with primitive variable formulations. In this approach, no assumptions have been made other than independence in the axial direction. The full two-dimensional Navier-Stokes equation in the r-a plane is used. The commonly used simplifying assumption of axisymmetry is not used. A numerical technique based on a newly developed spectral-difference method is used to solve the equations. The spectral-difference method is a multi-domain, and multi-dimensional extension of the Jacobi polynomial collocation technique. The computational grid for the inlet section is composed of 25 sub-domains which result from five partitions in the angular direction and five partitions in the radial direction. Several test cases are used to validate the appropriateness of the numerical model.

Jan 1, 1995

By Charles W. Rountree

Industrial Engineering in the industrial world is a relatively new field, having been conceived about the turn' of the century by Frederick W. Taylor, who was not satisfied with the hit-or-miss methods of evaluation and estimation. Through crude Industrial Engineering techniques never before used, he completely changed the bricklaying industry so that work accomplished was more than doubled. To help us better understand what we mean by Industrial Engineering, I think a very simple definition Is in order. Industrial Engineering is a scientific approach to problems in cost, production and operations: and is designed to provide a means of increasing producitivity and reducing costs through standards measurement and standardization of the best methods, practices and equipment, There are many complicated definitions, but pure and simply, it all boils down to providing the means for increasing productivity and reducing the cost. Industrial Engineering has been applied in manufacturing since Frederick W. Taylor?s time and in the last 20 years has grown in stature by leaps and bounds. It is a basic function of successful manufacturing companies and is an accepted fool firmly entrenched in manufacturing organizations. You may know of some successful manufacturing companies that do not employ Industrial Engineers as such, but someone in that organization is doing Industrial Engineering work. They have standards and controls whether they call it Industrial Engineering or not. The manufacturing industry has benefited from this tool; other wise, it would have been discontinued long ago.

Jan 1, 1958

By K. F. Unrug

Extrapolation of the rock properties obtained from the cores exploration holes to the surrounding areas often causes problems because of frequent sudden changes in the geologic composition of strata. To address this problem, the author has been developing a method of rapid strength testing "in situ," with application of a borehole penetrometer. This method, as opposed to conventional laboratory testing, does not require rock samples to be retrieved and handled/machined before testing. The results are generated by strength determination on the wall of a drill hole at a site. The newest development is a borehole penetrometer that requires only a 1.38.mm (1.5 in) diameter hole. The small diameter of the penetrometer body allows for drilling test holes with production mine equipment such as roof bolters. It opens the possibility of broad application in coal mines, as well as in hard rock mines and tunneling. The principles of the apparatus are described and are illustrated with examples of its applications.

Jan 1, 1999

Coal fly ash and flue gas desulfurization (FGD) sludges can be returned to mine pits, fills and revegetation zones in Virginia by regulation if (and only if) a positive beneficial use can be shown. Utilization of alkaline fly ash for control of acid drainage from pyritic coal processing waste piles, and use as a soil amendment for revegetation, are the two dominant beneficial uses proposed over time. Both applications must be controlled by the basic chemical properties of the ash proposed for utilization. Currently, public concerns over long-term As and Se leaching from various applications are increasingly driving regulatory options for mine site utilization. Many fly ash materials are relatively low in inherent alkalinity or neutralizing ability, and certain ashes are actually acidic. Failure to add sufficient total alkalinity will result in strong acidification of the ash utilization zones, stripping heavy metals like Mn, Zn and Cu from the fly ash matrix. Similarly, if alkaline ash is loaded into non-acid forming coal wastes at high rates such that leachate pH is > 9.5, significant leaching of As and Se has been documented in large scale laboratory leaching columns. Utilization of fly ash and FGD as a mine soil amendment for revegetation is based upon combined liming and water holding capacity benefits, however, levels of soluble salts (primarily sulfate and borates) limit one-time application rates to 100 Mg/ha or less.

Jan 1, 2006

By L. John Minnick

Extraction of crude ores and minerals inevitably produces various by-products either as a result of nonusable residues or as waste by-products from process operations. Thus for each 100 tons of coal extracted in a strip mine operation, one can expect to produce 25 tons, or more, of mine refuse. In addition, the amount of ash produced from the burning of coal will represent 10 to 20 percent of the weight of coal burned. With the advent of lime/limestone scrubbers now being installed on many power plants, an additional by-product is produced that in most instances is equal in volume to the sluiced fly ash. Statistics developed by the National Ash Association have indicated that sluiced waste from power plants in the United States currently exceeds 25 million tons per year (dry basis). Overall mineral industry statistics (copper mines, etc.) indicate better than 200 million tons per year. In the past it was general practice to send most of these waste materials to holding ponds or lagoons simply as a means of disposal or "throwaway" of unwanted by-products. Unfortunately modern society has reached a stage where these large quantities of waste materials are creating monumental environmental and economic problems that need urgent attention. Among these problems are concern for loss of future usable land, pollution of ground water, loss of potential mineral reserves, and loss of opportunities to recycle or use these by-products for the benefit of future generations. An example of the latter is the serious shortages of construction quality aggregates that can be replaced with some of the by-products produced from waste materials from the extractive and chemical industries.

Jan 1, 1975

By Ronald O. Harma

Iron ore pellets made from concentrates produced from low grade iron ores are the primary iron bearing feedstock for iron making in North American blast furnaces. Steelmakers are demanding increasingly higher quality to provide for improved blast furnace productivity, efficiency, product quality and environmental compliance. Unfortunately, this higher quality iron ore product must be produced from the vast deposits of low grade iron ores that are becoming increasingly poorer in quality with regard to mineral liberation and ease of concentration. Since some of these low grade iron ores require grinding to as fine as 90% -500 mesh (25 microns) for liberation and since more of the silicious gangue and other minor undesirable constituents must be removed to provide the higher quality, we have come to depend on flotation to do the added work. Flotation technology and other preflotation unit operations must improve to meet these increasing demands. In many cases, flotation equipment, reagents and circuit operating performance have improved little during the last two to three decades. Mechanical flotation cells have grown from 14 cubic meters (500 cubic feet) to over 84 cubic meters (3000 cubic feet) to help reduce capital and operating costs; however, flotation metallurgical performance has not improved, Column flotation has only recently shown promise in improving metallurgical performance for iron ore rougher flotation. Previous column flotation success was mainly in scavenger and cleaner flotation steps for treating minerals other than iron ore. Although some new flotation chemicals have been developed for removal of silica and other minor constituents under widely varying mineralogical scenarios, recovery of iron mineral has not improved. The operation and control of flotation circuits have become more challenging because of the increasing workload on flotation. Better sensing, process control and operation of flotation circuits are essential as we go forward. Iron ore upgrading by flotation can be classified into either anionic or cationic methods. Anionic flotation of either iron oxide or silicious gangue is accomplished by collector type, pH control and selective chemical activation . Similarly, cationic flotation of silica or iron oxides is accomplished by collector type, activation and/or pH control. Removal of other minor constituents is achieved by using specialty chemicals under controlled conditions for preflotation, co-flotation or post flotation steps. Generally, anionic flotation is used for floating cleanly liberating crystalline oxidized iron ores such as hematite, specularite and martite. Earthy and hydrated oxides such as hematite and geothite can be upgraded with either anionic or cationic collectors after controlled dispersion of slimes or prior removal of slimes. Anionic flotation of silicious waste can be achieved by calcium activation of silica. For magnetic iron ores small amounts of locked silica particles (middlings) can be removed by cationic silica flotation, which is the only method in commercial use in North America today. Historically the efficiency of these iron ore flotation processes has been restricted by the loss of fine iron particles (minus 500 mesh) to the tailings product. New technology is required to overcome this loss and improve overall flotation performance. Development of technology for more selective separation of silica and other minor undesirable constituents from iron ore will provide both quality and cost benefits to the iron and steel producers. Development of future iron ore production in North America will face stiffer technical challenges. These new and undeveloped iron ore deposits are largely oxidized (non-magnetic) and by nature contain more slimes and other undesirable constituents. Unless other new technology evolves, flotation will be the major treatment process required to upgrade these difficult low grade iron ores.

Jan 1, 1993

By H. Soto

As a follow-up to a laboratory study, a pilot scale column for the flotation of coarse particles was designed and then tested in two different applications. In the first test, the concentration of a coarse phosphate ore (normally beneficiated by skin flotation in spirals) was carried out in a flotation plant in Florida. In the second pilot test, the column was used as a scavenger cell in the coarse flotation section of a potash beneficiation plant in Saskatchewan, Canada. Particle size of the phosphate feed was of the order of 0.6-1.0 mm and the potash feed 1-3 mm. The column was 1 feet diameter and was fed at rates between 0.5 to 1.4 tph. The effect of operating variables such as air and water flow rates, bubble size, frother concentration, residence time, sparger, etc were evaluated. The most important factors in column performance were found to be bubble size, air flow rate and the thickness of the froth bed. Best results were obtained in the absence of a froth bed, with low air flow rates and with small bubbles. The paper presents comparative performance and discusses details of the column design. Phosphate recoveries in the column were better than 90% whereas the conventional skin flotation circuit normally yields about 60% recovery for a comparable concentrate grade. Potash recovery from the tailings of the conventional flotation circuit was as high as 42% recovery. Particle size distribution of the potash concentrate was coarse enough to meet requirements for potash fertilizer.

Jan 1, 1993

By K. Perry, R. Eades

"Highwall miners continue to be implemented by operations to increase recovery, improve margins, and justify higher stripping ratios as high quality surface reserves become increasingly rare. Many times, operations facilitate projected underground operations by leaving an intact highwall for development purposes. These facts result in larger highwalls that are left standing for increased periods of time prior to reclamation. As a consequence, worker exposure and risk is also elevated, resulting in higher potential for accidents or fatalities relating to surface highwalls. Highwall stability is a complex issue, dependent on both geologic and mining factors. Dynamic numerical modeling offers the capability to assess possible stability issues related to blasting-induced ground vibrations. Research has been conducted to evaluate the effect of highwall stability due to ground vibrations from blasting events. Additionally, the relationship of amplitude and frequency, and their impact on highwall stability is investigated. The results of this modeling indicate that amplitude has little impact on stability. However, frequency has a significant impact on highwall stability. INTRODUCTION The number of mining fatalities has declined since 2010, and 2016 is currently on pace to continue this trend (MSHA 2016). This decline can be directly correlated to the decline in surface mining activity and the overall decline of the coal industry. However, since 2002 the percentage of surface coal mine fatalities associated with highwall activities remains relatively high, constituting approximately 15% of all surface mine fatalities. 2014 was the first year with a highwall failure fatality since 2011. Most recent surface coal mining fatalities are associated with machinery and haulage. Table 1 provides a summary of the total surface coal mining fatalities, and the number of highwall failure fatalities dating back to 2010.Highwall stability is a complex issue, dependent upon geology and geologic discontinuities within the rock mass, along with highwall geometry, standing time, and applied stresses. Another possible concern that has not been previously investigated is the effect of blasting-induced stresses on highwall stability and the stability of web/barrier pillar systems as a result of ground vibrations from blasting events. Many modern surface coal mines employ numerous extraction fronts that rely on blasting for primary rock breakage. This results in highwall and highwall pillar systems experiencing blasting-induced stresses of many different types and magnitudes."

Jan 1, 2017