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By John W. Trammell

The White Pine Mine is situated in Ontonagon County, approximately six miles south of Lake Superior, in the Upper Peninsula of Michigan (Figs. 1 and 2). The ore body mined by White Pine Copper Company occurs in the lower - most 20 to 25 feet of the Nonesuch formation, a series of middle - to upper Keweenawan shales, siltstones, and sandstones. This paper elaborates on the solution of problems in ore grade control and mine planning arising from the presence of an essentially barren sandstone stratum within the ore body.

Jan 1, 1964

By D. Newman

Ground control is critical to the success of a safe and productive underground stone mining operation. The primary focus of the ground control engineer is the stability of the roof or back; development and benched pillar stability; stability of the sill pillar between vertically adjacent mining levels; and floor stability. Roof stability begins with the selection of a stable back horizon based on the presence of a thin shale parting, stylolite or other discontinuity from which the production shot can easily peel away, leaving a stable back stratum. Bed thickness, fracture spacing, jointing and the material properties of the roof strata control the room width; the decision whether to bolt the roof; the bolt length, type and diameter; and the spacing of the roof support. Horizontal stress controls the header and crosscut azimuth. The mine operator should avoid driving perpendicular to the maximum horizontal stress direction. Where this is unavoidable, narrowing the opening width, narrowing pillar centers, increasing the support density and using three-way intersections are alternatives to remediate shearing along the roof-rib interface. Stable pillar dimensions depend upon the interaction of the vertical stress resulting from overburden thickness and multiple-level interaction of overlying level or levels; the mining height during development and the final mining height after floor shots are taken during benching; the presence of faults, folds or joints passing through the pillar; and limestone lithology, recognizing that the presence of oolitic bands, shale partings, joints and bentonite beds creates zones of weakness that can destabilize an otherwise competent pillar. Floor stability is typically not a significant issue for underground stone mines because the bearing capacity of the stone typically exceeds the vertical pressure transferred through the pillar. However, floor heave can be a ground control issue where shale partings, moisture-sensitive strata, weak stone bands or horizontal stress is present. Roof stability and pillar stability problems can be initiated as the floor heave enables the pillar and roof to settle. To illustrate these ground control issues, this paper presents four case histories that are a mix of ground failures and successful mining. The focus is on the geotechnical data required for roof, pillar and floor design and stability analysis.

Jan 8, 2017

By B. J. Timmons

An initial point that I would like to make very emphatically?and as our title might erroneously suggest for those of you old enough to remember . . . Peter Harben and myself do not intend to shoot ourselves in the foot. We derive our livelihood from a number of aggregate, industrial and other minerals producers, both here in the United States and outside. This paper, therefore, is a fence-straddler or for information purposes (we hope) only, rather than any "fur or agin" stances. In essence, some of you may consider it a U.S.G.S. publication! In fact, we hope that it serves to inspire aggregates producers to do some radical thinking, to promote introspection, and to that end it would benefit both domestic and foreign producers. The title could be shortened into a brief question of "Aggregates Travel?" with an emphatic no for the answer. In the past, the success of a construction materials venture depended upon your ability, through siting, to provide the customer f.o.b. the job site, a product at the lowest possible cost.

Jan 1, 1987

By Tsunenori Shibata, Kazunori Jimbo, Kaoru Toya, Masafumi Matsumoto, Jinya Mitsui, Toshinori Tsuji

"The Toyama Line is under construction as a natural gas pipeline with a length of 102 km from Itoigawa City to Toyama City. A 2 km-long tunnel section of the pipeline that we are reporting here is being excavated in a mountain area away from an urban area. The geology under which the tunnel is constructed is collapsible fractured breccia slate and Holocene sandy soil. Other tunnels of the Hokuriku Expressway and Hokuriku Shinkansen are in service above the tunnel route. From the starting shaft on Toyama side, conventional tunneling was adopted to facilitate excavating the base rock layer and maintain enough distance from the Hokuriku Expressway tunnel. From the starting shaft on the Itoigawa side, TBM tunneling was adopted to cope with the unconsolidated soft ground for a 200 m-long section from the shaft. We will discuss the issues and countermeasures concerning the selection of a tunnel route and excavation methods, performance of both conventional and TBM tunneling, and underground connecting of these tunnels excavated by conventional (NATM) and TBM methods under a high groundwater pressure up to 1.2 MPa. INTRODUCTION AND BACKGROUND The International Petroleum Exploration Teiseki Co., Ltd. (INPEX) is constructing a high-pressure main pipeline network in the Toyama Prefecture area to promote the use and reliable supply of natural gas as shown in Figure 1. As part of the Toyama line project that has a total length of 102 km, A-1 construction, the nearest section to the tunneling starting point in Itoigawa City, where various tunnel excavation methods have been adopted to install the high-pressure pipeline 20 inches in diameter, a 2 km tunnel in the A-1 construction section discussed here is to be excavated by conventional and TBM methods in a mountain area. Based on environmental studies such as traffic jams due to frequent traffic of heavy vehicles disposing of soil, and the effects of dust, noise and vibration during construction, we selected the route to install the gas pipeline in a mountain area as shown in Figure 2, where the impact on the surrounding environment could be minimized."

Jan 1, 2016

By J. Herhold, S. Plaum

The focus within the economical optimization of projects, which are conducted underground, shifts more and more towards the conduction of construction work underground. Underground operations can be defined in a wide range of various projects, from underground mining tasks to the construction of engineering structures. Within these projects the conduction of construction work cannot only be defined as absolutely necessary, but sometimes also as optimizing for underground processes (e. g. installation of workshops underground to support the mining processes). Even though the conduction of underground construction might cause positive outcomes concerning the productivity, it also tends to be challenging due to local (sub-surface) conditions and influences. To minimize the risk of failure and sudden events within in the conduction of construction work underground, the tool “work preparation” shall be used. Under the given constraints, such as local influences, expected construction work and set time frame, the conduction of the construction work will be planned in advance by consideration of the construction logistics as well as the selection of a fitted construction technique. PROBLEM DEFINITION Economic Challenges - Raw Material Extraction Enterprises in the construction, mining and raw material extraction industries are increasingly under the pressure to perform economically to sustain their position on the global market. Profitability, efficiency and productivity are the basic conditions to be an active participant on the global market as well as a business partner and contractor for mining and construction projects or projects related to the extraction of raw materials. The completion of large-scale as well as common construction projects above ground has been under the pressure to minimize costs and time whilst maximizing the potential outcome, in the meanings of quality and economic gain, for more than a decade now. Whereas the construction industry has to fight the competition on the market with efficient project outcomes, the mining industry has to find ways to perform efficiently to further conduct the extraction of decreasing raw material deposits. The ongoing exploitation of existing raw material deposits to satisfy the constantly increasing raw material demands world-wide, led to the predicament that economically mineable deposits have decreased dramatically. Even tough mineral deposits do still exist on a global level, near-surface deposits decrease rapidly. Therefore, the extraction of raw materials within mining operations will be relocated further away from the surface in greater depths. With the growing distance from the surface to the mineral deposit, the extraction costs will increase many times over. With that in mind, the extraction costs will increase whilst the economic efficiency will decrease. The extraction of certain deposits will no longer be profitable with the common approach. To further extract raw materials efficiently even in greater depth, companies have to change their practice in different ways. That leads to the fact, if the deposits are in the depths, where the extraction processes won´t be economically, other (support) processes have to be in order to guaranty an economical corporate process itself. This precept will divert the focus from the actual mining process to support processes, where potential for optimization still can be found, as shown in figure 1.

Jan 1, 2019

By Douglas H. Bolton

In recent years, equipment manufacturers have been busy developing remote control systems to catch up with the sophistication and efficiency of continuous miners. Now the tables are turned, and manufacturers are undertaking the new challenge of upgrading, refining and equipping continuous miners to take full advantage of the capabilities made possible by modern, successful remote control systems. Because the operator can safely advance the miner farther without pulling out for roof bolting, continuous miners now need to be equipped with means of complying with correct face ventilation, dust suppression, methane detection, diffusion and improved lighting. Some of the exciting possibilities being developed to catch up with remote control include feedback controls using laser beams as datum points, coal sensing devices with feedback signals to show the operator what the machine is doing, show where it is relative to the coal seam, how hard it is working, and more sophisticated use of cyclic control. Mining machinery manufacturers have accepted the new challenges, and faster, safer mining procedures are already in sight.

Jan 1, 1975

By C. C. Jobes

Operating large face equipment, such as continuous mining machines, is one of the most basic and most dangerous elements of an underground coal mining operation. The operator usually performs cutting and tramming tasks in a restricted workspace with reduced visibility. During the execution of these tasks, operators often cannot see all of the locations needed to safely operate the continuous mining machine (CM ), which has sometimes resulted in accidents. In an effort to prevent these accidents, researchers at the National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory, examined the continuous mining machine operator?s current information cues, or visual attention locations, so that risk of injury relative to the task, equipment and workplace environment can be evaluated in the future. The eventual goal is to develop interventions to enhance the information cues, and thereby increase the safety and health of machine operators. This paper details the operator interview process, determination of visual attention locations (VALs) and simulation of various mining scenarios.

Jan 1, 2011

Gold cyanide equilibrium adsorption isotherms in the loading range typical of operating carbon-in-pulp/carbon-in-leach plants have been established and the effect of various cations and the presence of copper cyanide species quantified. It was found that the equilibrium loading of gold was enhanced by the presence of sodium or calcium, with calcium having an order of magnitude stronger effect. The presence of copper has an adverse effect on the equilibrium loading of gold. A unified model was developed to predict the effect of sodium and calcium concentrations in solution and the competitive carbon adsorption of copper on the equilibrium loading of gold on carbon. A satisfactory agreement between the measured gold equilibrium loadings and the model results was obtained over a wide range of solution conditions.

Jan 1, 2010

By J. Organiscak

A majority of continuous mining machines employ a water spray system and a machine-mounted flooded-bed scrubber to suppress and capture dust during coal mining. These machine-mounted dust control systems must be designed to function within the localized face ventilation system at the mining section to control both dust and methane. Spray systems can impede or improve the scrubber effectiveness in controlling dust or methane at the mining face. Laboratory experiments were conducted to examine the effect of spray type, spray pressure, machine body blocking sprays and scrubber airflow on dust and gas levels, while using a 12.2-m (40-ft) exhaust ventilation curtain setback from the face. These experiments were conducted with the mining machine positioned at the end of a simulated 6.1-m (20-ft) sump and slab cut. Results indicate that the hollow cone nozzles with blocking sprays best complement the flooded-bed scrubber performance in an exhaust ventilation system. This external spray system notably reduced dust and gas levels on the off-curtain side of the mining machine for both the sump and slab cut compared to the flat spray nozzles. Higher scrubber airflows reduced dust and gas levels on the curtain side and in the return of the continuous mining machine. The remote operator position, located on the off-curtain side and parallel to the inlet end of the exhaust curtain, sustained the most stable and lowest dust levels around the mining machine.

Jan 1, 2010

By C. P. Blair

In discussing so-called "volume rates" for the movement of coal, I start from one basic premise: That it is the job of the railroads to devise rates which will move the traffic, while at the same time assuring a fair return on their investment. No matter how reasonable and nondiscriminatory freight rates may be, if they fail to attract and hold traffic to the rails, they are utterly useless - both to the carriers and the shipping public. And it will be my purpose here to show that under certain circumstances the use of volume rates by the railroads enables them. to hold traffic which would otherwise be lost, and to avoid needless dissipation of revenues, Properly employed, volume rates should benefit both the coal industry and the railroads, I do not, however, advocate the discarding of the carload as the basic rate-making unit. Far from it. Sound operating reasons dictate the making of rates based on car- loads, and the tradition of carload rates has a firm foundation in railroad operating costs, many of which vary directly with cars handled. In short, the carload was, Is and, in my opinion, will continue to be the basis for most rail rates on coal, as well as on other commodities. But change is an inevitable result of progress, and we should not be so bound by tradition that we are unwilling to try novel methods of ate making, should the circumstances require, The modern rate maker must, now and then, run the risk of being called an iconoclast if he is to keep up with the times. As T will point out, volume rates were for many years rejected by both the Interstate Commerce Commission and the railroads, But now both the Commission and the carriers have come to recognize that under proper circumstances and conditions volume rates are a powerful and effective tool.

Jan 1, 1959

Anomalous geologic or stress conditions ahead of the longwall face can cause great harm to both the individual miner and the mining operation as a whole. The U.S. Bureau of Mines has been developing seismic tomography techniques to image the panel ahead of the face. This paper presents the results of a field effort in which a 60-m (200-ft) segment of a longwall panel containing a fault zone was surveyed daily as the face approached. Stress distribution, geologic structure, and dynamic elastic properties within the panel were plotted and compared to static laboratory measurements. The surveys successfully imaged an anomalous stress concentration, likely influenced by the presence of the fault zone. The calculated dynamic physical properties generally agreed with laboratory measurements.

Jan 1, 1995

By Moreno Pescara, Luca Soldo, Piergiorgio Grasso

"Risk management in tunneling is more important today than it was a few years ago, considering increasing demands for safety and environmental and socio-economic sustainability, which are now required by citizens, owners, lenders, and insurers. Moreover, our current risk management philosophy should not only address risk avoidance and mitigation, but should also be used as a means of value creation, benefiting the overall project. Given the strategic implications of risk management, the authors intend to present, in this paper, a comprehensive overview of references and experiences from current practice—e.g., what is missing or weak, as well as possible or necessary developments that can have a key role in implementing effective risk management, particularly for a project’s design and construction phases. Therefore, as God has set some things in broad daylight; as he has given us some certain knowledge, though limited to a few things so, in the greatest part of our concernments, he has afforded us only the twilight, as I may so say, of probability (John Locke) PREFACE Many large-scale engineering and construction projects suffer millions of dollars in cost overruns, delays in design and construction, and operability troubles once finally completed (Edward W. Merrow, 2011). The undesired effects of these problems can become disastrous for large-scale megaprojects (those that typically cost US$1 billion or more), particularly considering that these are increasingly used as the preferred delivery model for infrastructure (Bent Flyvbjerg, 2014), often in public-private partnerships (PPPs). McKinsey G.I. (2015) has estimated that bridges and tunnels average 35% in cost overruns, and roads 20%. Some of the values published by Flyvbjerg (ibidem, 2014) for projects with relevant underground elements are the highest, with cost overruns from 60% to 300%. The analysis of 32 other case histories (from 1994 to 2010) given by Hartmut, R. (2011, IMIA Annual Conference, Amsterdam) indicates an average increase of costs around $55 million, with a 20-month average delay."

Jan 1, 2016

By S. K. Kawatra

Outokumpu Electronics has designed a new on-line coal slurry ash analyzer, based on an instrument developed at Michigan Technological University. The primary goal was to build an accurate instrument at the lowest possible cost. The instrument determines ash content from measurements of x-ray backscatter, iron Ka fluorescence, and low-energy y-ray absorption. It is capable of measuring the ash content with a standard error of 1.1% ash over an analysis range of 9-21% ash and 7-22% solids. The analyzer was tested on coals from United States, Poland, Great Britain and the USSR.

Jan 1, 1992

By B. Caines

Much of the mining industry in North America is in a crisis state. Host producers are operating at production levels well below capacity, some have been merged or sold, while others have been mothballed or closed permanently. For many of us still operating, the future is uncertain. Despite the many cutbacks and closures, there is still an abundant supply of minerals in the world market and there is almost no hope for any relief on price pressures on most mineral commodities in the near future. The Iron Ore Company of Canada (IOC)operates an iron ore mine, a concentrator and a pellet plant known as the Carol Project located in Labrador City, Newfoundland. This concentrator and the pellet plant have the annual capacity to produce 20 million and 10 million tons respectfully. A company owned and operated railway links this operation with the dock terminal facilities in Sept Iles, Quebec.

Jan 1, 1987

Heap leaching has become one of the prime technologies used for the recovery of precious metals from low-grade ores over the past ten years. The recovery process involves mining and stacking the ore on engineered leach pads, with or without crushing and/or agglomeration, followed by leaching with a low concentration sodium cyanide solution. The metal-bearing, pregnant solution is then processed by zinc precipitation or activated carbon absorption to extract the precious metals. The leaching process continues until all economic metal values are removed at which time the spent heap leach pads, the leached materials and excess process solutions require decommissioning. The management of these solutions may present a potential challenge for successful and environmentally sound decommissioning due to their composition, volume or continuity of generation from the spent ore even though active leaching has been terminated. The principal objectives of solution management in decommissioning spent heap leach pads are to meet all operative environmental regulations in a cost-effective manner and to leave the pads in a condition where they do not present a long-term liability either to the operator or to the environment. This involves the reduction in volume of the residual process solutions and/or treatment of these solutions to where they meet applicable water quality criteria. In the past, the environmental and economic aspects of decommissioning and solution management have been overlooked or under-estimated during the planning of mining operations. As a result, there is a potential for long-term liabilities and costs to be recognized only at the end of active leaching, a time at which operating revenues and cash-flow are minimal. Therefore, the decommissioning process requires addressing at the mine planning stage and agencies now require that a plan for solution management after the cessation of operations be submitted prior to initiation of mining. This paper discusses aspects of process solution management during decommissioning, both in terms of quantity and quality, and how potential issues may be recognized and planned for in the initial stages of heap leach design.

Jan 1, 1992

By T. W. Beck

Drilling into coal mine roof strata to install roof bolts has the potential to release substantial quantities of respirable dust. Due to the proximity of drill holes to the breathing zone of roof bolting personnel, dust escaping the holes and avoiding capture by the dust collection system pose a potential respiratory health risk. Controls are available to complement the typical dry vacuum collection system and minimize harmful exposures during the initial phase of drilling. This paper examines the use of a bit sleeve in combination with a dusthog- type bit to improve dust extraction during the critical initial phase of drilling. A twistedbody drill bit is also evaluated to determine the quantity of dust liberated in comparison with the dust-hog-type bit. Based on the results of our laboratory tests, the bit sleeve may reduce dust emissions by one-half during the initial phase of drilling before the drill bit is fully enclosed by the drill hole. Because collaring is responsible for the largest dust liberations, overall dust emission can also be substantially reduced. The use of a twistedbody bit has minimal improvement on dust capture compared with the commonly used dust-hog-type bit.

Jan 1, 2014

By J. E. Carr

A bewildering number of continuous thickeners and clarifiers are used in mineral industries and other heavy industries. General types are: 1. Conventional Thickeners (Fig. 1). 2. Thickeners with Flocculating Feedwells (Fig. 2). 3. Solids Contactors (Fig. 2). 4. Tray Thickeners (Fig. 3). 5. Lamellas (Fig. 4). 6. Conventional Thickeners with Lamellas 7. High Flow, Fluid Bed Thickeners (Fig. 5). These units must be adapted to varied applications. They must provide operating flexibility to meet process needs. Such factors multiply the decisions which must be made prior to the selection of a thickener. The seven types of thickeners listed above, with their variations, share design concepts which limit their application and which can be used to evaluate their performance. Some of these are listed: 1. Feed velocities must be limited and/or controlled. 2. Natural or reagent flocculation is necessary. 3. Horizontal settling area is the basis for capacity. 4. Overflow velocities must be limited and/or controlled. 5. A controlled underflow is necessary. Applying these needs to the basic process concepts is thickener selection. The basic function of a thickener in the minerals industry is the separation of a thickened sludge containing fine solids from water. To this primary separation function are frequently added others to give a list as follows:

Jan 1, 1977

The effects of additives, sodium hydroxide, sodium carbonate, sodium oleate, oleic acid and polyacrylic acid, on stirred media milling of limestone have been investigated. The results are evaluated in terms of specific surface area, specific energy and energy efficiency as a function of additive dosage, polymer molecular weight, solids concentration and relevant operating variables. Use of additives generally results in changes in specific surface area and energy efficiency, while under certain conditions a more than 100% increase in these parameters can occur. Relevant interfacial properties have been measured and milling mechanisms involved are explored particularly in terms of the effect of additives on the flow patterns at higher solids concentration.

Jan 1, 1996

By John E. Young

United States Steel Corporation's Winifrede Mine is operated by Lynch District in the mountainous region of Eastern Kentucky. This region is characterized by narrow mountain ridges and precipitous slows which present both an opportunity and challenge in the design and selection of coal handling facilities for the movement of coal from the section belts to the railroad cars. The narrow finger ridges precluded use of underground haulage and, thereby, presented the opportunity to use high capacity equipment on the outside bench. The precipitous mountain slopes, steepest at the Winifrede seam horizon, presented a challenge to select a solution for lowering the coal approximately 1000 feet from the seam level to the valley floor railroad load-out point. It was evident from the start of planning that these two factors predominated; namely, rail haulage and coal lowering, and solutions to these would determine the final design of the Winifrede Mine coal handling facilities.

Jan 1, 1970

By J. R. Patts, J. P. Rider, J. A. Organiscak, A. B. Cecala

"The U.S. National Institute for Occupational Safety and Health completed a 15-month study at an underground limestone mine crusher booth that evaluated three research parameters: (1) the effectiveness of a filtration and pressurization system for improving the air quality inside the operator booth, (2) the relative effectiveness of ? > 99 and ? > 95 experimental prototype filters in the system, and (3) the performance of three different cab pressure monitoring devices. The protection factor was quantified monthly using particle counters in the respirable dust range of 0.3 to 1 µm particle size, and gravimetric dust samples were gathered at the beginning and end of the overall study. Under static (closed-door) conditions, the filtration unit offered a gravimetric calculated protection factor between 10 and 31, depending on the filter type and loading condition. The monthly particle counting analysis shows that the ? > 95 filter offers a protection factor nearly five times that of the ? > 99 filter, where n = 15 samples. The booth pressure monitors were tested and proved to be a valid indicator of system performance over time. IntroductionDesigned and installed correctly, enclosed cabs, operator booths and control rooms offer mine workers protection from noise and physical hazards, such as flying rock and debris, as well as a more comfortable environment in regards to temperature and humidity (Organiscak et al., 2016). While it is easy to quantify the operation of a cab’s air-conditioning unit by measuring the temperature, or observe whether the cab offers protection from flying debris, it is somewhat more difficult to quantify its performance in reducing respirable dust hazards.The U.S. National Institute for Occupational Safety and Health (NIOSH) has been conducting applied research to improve the air quality inside the enclosed cabs of mobile equipment, resulting in the mathematical modeling of enclosed cab filtration systems (Organiscak and Cecala, 2008). The same principles that govern the performance of filtration systems on mobile equipment are applicable to stationary enclosures such as operator booths and control rooms (Noll, Cecala and Hummer, 2015). While stationary enclosures are similar to mobile cabs, the work area can be significantly larger. Workers in booths and control rooms also tend to stay within the enclosure for a greater percentage of the day as opposed to workers on mobile equipment who enter and exit frequently."

Jan 1, 2018