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By William N. Poundstone

Since World War II, when off-track mining became popular, mining machinery has undergone much change. However, the change has been basically to make the machines more powerful, more productive and more reliable. Little change has been made, in this period, in the basic mining system. While steady improvement was made in productivity until the passage of the new Federal Coal Mine Health & Safety Act, I believe that the cost Co benefit ratio of further improvement from this basic approach of improving the existing extractive tool is not as promising as I believe may be obtained from a new approach. Consequently, six years ago Conoco and Consol undertook a comprehensive long-range R&D program to see if improvements of a more basic nature could be made in underground mining. We concluded early in our program that while many things currently limit the rate of production such as the rate at which roof can be supported, time needed to advance ventilation systems, time required to clean up and rock dust, time required to maintain and service equipment as well as time lost due to haulage deficiencies, that the key to improvement was a truly flexible continuous high capacity haulage. With face equipment in use today, mining rates can be increased with such a haulage system where the ability to support the roof exceeds the ability of conventional haulage equipment to remove the coal. More importantly, if we could develop such a system, it would set the stage for development of far more sophisticated methods of mining at the face than exist today, and as new and more dependable mining machines and methods are developed, continuous transportation will enable the gains envisaged in production to be realized.

Jan 1, 1974

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 G. M. L. Robinson

The Clean Water Act, as administered by the Environmental Protection Agency, has mandated industry, government and the public to comply with potentially conflicting and vague water quality statutes, regulations and guidelines. Universal regulatory strategies have been developed which have introduced and have created regulatory, compliance and institutional conflicts. Conflicts have been created because National water quality performance goals and design standards are vague, and, in many cases, cannot be scientifically justified. Because of regulatory technical requirements to define background and environmentally impacted water quality characteristics, the ability to achieve regulatory compliance is difficult. Difficult issues requiring resolutions includes but are not limited to site specific surface and ground water quality classification systems, water quality standards and guidelines, point and non point pollution sources etc. Because of these statutory and regulatory complexities, a confrontational regulatory system has been created as it relates to: - defining performance criteria in relation to design criteria; - resolving water quality statistical compliance conflicts; - defining laboratory precision requirements; - determining background groundwater characteristics; and - locating a representative point of compliance. Because of these complex regulatory issues, the ability to balance goals, needs and economics has not been achieved or in many cases has not been attempted, without legal intervention. A few examples illustrating where water and waste management compliance conflicts have been experienced.

Jan 1, 1992

By J-M M. Rendu

Geostatistics are increasingly recognized as powerful tools for reserve evaluation and grade control. It is also generally accepted that geologic input is required for the results of a geostatistical study to be meaningful. The role of the geologist is significant at all stages, whether it be to oversee the creation of the database, to assist in the statistical and semivariogran studies, to ensure appropriate block evaluation and kriging, or to review the results obtained. However the link between geology and geostatistics is often complex and not well understood. A presentation is made of the areas where geologic input is needed, and of the tools which the geologist should have at his disposition to ensure that his role is fulfilled. Organization of a Geostatisticel Study To be acceptable as the basis for financial investment, a geostatistical reserve estimation should be composed of four phases, the last phase being optional: Phase 1 - Background discussions, Phase 2 - Computation, Phase 3 - Reserve reporting, Phase 4 - Reserve audit. During the background discussions (Phase 1) the role of the geologist is primordial, as it is then that most decisions will be made concerning the geologic factors to be included in the geostatistical model.

Jan 1, 1985

By R. Gray

"Experience from Australia has identified what is referred to as non-conventional surface subsidence behaviour. This occurs under irregular surface topography, resulting in valley closure, valley floor uplift or “upsidence”, and far-field horizontal movements – even occurring beyond conventional “angle of draw” limits. This paper discusses such behaviour recently observed in Pennsylvania and focuses on the 2005 case of Duke Lake Dam in Ryerson Station State Park. In July 2005, there was a significant increase in water leakage through a number of growing cracks in the dam leading to the dam being breached to avoid an uncontrolled failure. An underground longwall mine was located approximately 900ft to the north, mining at depths of 330 – 720ft. Investigations (including a subsequent ground movement monitoring program) found a range of evidence in the vicinity suggesting that valley closure and far-field horizontal movements may have occurred resulting from the adjacent mining. The paper discusses the phenomenon of non-conventional subsidence behaviour and the Ryerson State Park case study, including an assessment of mining, geology and subsidence impacts and suggested ground behavioural mechanisms. INTRODUCTION Non-Conventional Subsidence The conventional understanding of coal mine subsidence on which most current subsidence understanding and prediction techniques are based, includes the concept of angle of draw which effectively limits the lateral extent of subsidence effects and impacts. Within this zone – above and marginally beyond the boundary of mining – downward vertical subsidence is the dominant component, together with localised horizontal movements towards the mined region, with related tilts and strains. However, more recent experience from Australia over the last two or three decades has identified what is referred to as non-conventional surface subsidence behaviour. This is found to occur in areas of irregular surface topography or variable terrain, and is characterised by phenomena such as valley closure, valley floor uplift or upsidence, and far-field horizontal movements, all of which can occur beyond the conventional angle of draw limits. NSW Department of Planning (2008) defined the conditions for both conventional and non-conventional subsidence behaviour as follows: “The conventional or general model of surface subsidence, which finds worldwide acceptance, is based on assuming the following site conditions:"

Jan 1, 2015

By M. Li, W. R. Reed, J. P. Rider, J. D. Potts

"The National Institute for Occupational Safety and Health (NIOSH) has recently developed a series of validated models utilizing computational fluid dynamics (CFD) to study the effects of air-blocking shelves on airflows and respirable dust distribution associated with medium-sized surface blasthole drill shrouds as part of a dry dust collector system. Using validated CFD models, three different air-blocking shelves were included in this study: a 15.2-cm (6-in.) wide shelf; a 7.6-cm (3-in.) wide shelf; and a 7.6-cm (3-in.) wide shelf at four different shelf heights. In addition, the dust-collector-to-bailing airflow ratios of 1.75:1, 1.5:1, 1.25:1, and 1:1 were evaluated for the 15.2-cm (6-in.) wide air-blocking shelf. This paper describes the methodology used to develop the CFD models. The effects of air-blocking shelves and dust-collector-to-bailing airflow ratios were identified by the study, and problem regions were revealed under certain conditions. The simulation results could be used for future development of dust control methods, particularly to address respirable silica dust, for a surface mine blasthole drill shroud.INTRODUCTION Surface blasthole drilling can generate considerable amounts of respirable silica dust. These high dust concentrations can be exacerbated by the high silica content as drilling cuts through silica-bearing materials such as sandstone and shale, causing overexposures for miners to respirable silica dust. These overexposures can lead to silicosis, an occupational lung disease that has no cure and is often fatal. A review of the Mine Safety and Health Administration (MSHA) respirable silica dust sample database from 2010 to 2016 for metal/nonmetal mining shows the following overexposure rates for occupations related to blasthole drilling: • 14.1% of rotary air drillers were overexposed to respirable silica dust (22 out of 156 samples) • 5.8% of rotary drillers were overexposed to respirable silica dust (9 out of 155 samples) • 7.3% of drill helpers were overexposed to respirable silica dust (3 out of 41 samples) • 7.5% of blaster/shotfirer were overexposed to respirable silica dust (3 out of 40 samples) Of significant interest is an x-ray surveillance study recently completed under the NIOSH Enhanced Coal Workers’ Health Surveillance Program (ECWHSP). This program offered free chest radiographs to surface coal miners in 16 states. Pneumoconiosis was found among 2.0% of the 2,328 screened miners with at least 1 year of mining tenure. Twelve miners had radiographic changes consistent with progressive massive fibrosis, and 9 of these 12 miners reported no underground mining tenure. All but 1 of the 9 miners worked at occupations that were in the vicinity of blasthole drilling, either as a driller, blaster, or blast crew member [1]."

Jan 1, 2018

By J. McCreedy

The Ontario Division of The International Nickel Company of Canada, Limited, operates five underground mines and one open pit on the rim of the Sudbury Basin located in the Province of Ontario, 230 miles northwest of Toronto. Four of the mines, Frood-Stobie, Creighton, Murray and Garson, lie on the South range of the Basin within a 10-mile radius of the City of Sudbury; the fifth mine, Levack, is on the North range, about 30 miles northwest of the city. The ores are mined primarily for nickel and copper, the principal minerals being pentlandite and chalcopyrite. Other elements recovered from the ores in varying quantities are platinum, palladium, ruthenium, iridium, rhodium, cobalt, selenium, tellurium, iron, sulphur, gold and silver. In 1962, the total underground ore production was over 10,800,000 tons which was mined mainly by blasthole and caving methods with the remainder by cut-and-fill, square set, and undercut-and-fill techniques.

Jan 1, 1964

By C. J. Newman

Prior to 1995, the smelting process at the Kennecott Utah Copper Corporation (KUCC) smelter consisted of Noranda reactors and Pierce-Smith converters. In the consideration of expansion opportunities, the existing process did not lend itself to a program geared towards processing the total output of KUCC mining and milling operations. During 1989 and 1990, a number of smelting options were evaluated. The final selection was the Outokumpu flash smelting process, coupled with the new Kennecott-Outokumpu flash converting technology. Facilities were designed and installed to process 1.0 million tonnes per year of copper concentrate, with the ability to expand to 1.2 million tonnes per year. Following the shutdown of the smelter facility utilizing the Noranda technology in May 1995, the flash smelting furnace commenced operation in June with the flash converting furnace startup following a few weeks later. The smelter has achieved design production targets and environmental goals. Current operating rates are at or above design rates for concentrate and matte processing. Emissions are lower than the permit levels and equate to less than 3.5 kg of S02 per tonne of copper. This paper outlines the design, construction, startup and the first two years of operation of the modernized KUCC smelter.

Jan 1, 1998

By H. F. Haller

Large volume sand plugs are placed in tunnels to stem underground explosions at the Atomic Energy Commision's Nevada Test Site. Placement through long, narrow accessways is like stemming coyote holes and blast chambers in mining and construction. Experience with several other methods showed that pipeline conveying could be preferable. Small scale tests justified predicting a placement rate of 20 y. p. h. at 1000 feet, with a modified gunite placer. The initial production trial placed over 2000 c. y. and was estimated to effect a small cost saving after paying for new equipment. Initial problems included duct replacement and supply delays, dust, and other personnel hazards. Operations analysis and SOP'S reduced delays during the second field trial, minimized hazards, doubled production. Re cent re search and operations analyses produced data on abrasion resistant ducts, identified minor equipment modifications which can improve production, developed techniques for impact compaction to 90% ?maximum? and for extension of the practical range to 2000 feet. Twenty-two illustrations include an air consumption-distance chart.

Jan 1, 1967

By P. T. Bissert, J. P. Ducarme, J. D. Noll, C. C. Jobes

"There have been about 42 fatalities in underground coal mines between 1984 and 2015 where the victim was struck, pinned, or run over by a mobile machine (MM) such as a shuttle car, scoop, or battery hauler. MSHA has issued a proposed rule requiring proximity detection systems (PDS) on MMs in an effort to prevent future fatalities. Currently approved PDSs use electromagnetic (EM) technology to detect the presence of a miner and impose machine controls to prevent contact. The disadvantages of an EM-based PDS on MMs include the need for a miner-wearable component (MWC), environmental interferences, EM interferences from other devices, and low localization range and accuracy. NIOSH researchers are investigating alternate technologies that could improve the capabilities of the current PDSs. Many technologies were reviewed, and NIOSH researchers identified RFID, LIDAR, RADAR, ultrasonic detection, and computer vision as candidates for PDS development. The performance characteristics of each technology and its applicability to an underground mining environment will be discussed, along with international developments and implementations, and the concept of sensor fusion. INTRODUCTION PDSs provide safety to mine workers by detecting their presence (and in some cases location) around a machine. These PDSs provide a warning zone, which triggers an alarm, and a stop zone, which halts the machine before it contacts the miner. The Mine Safety and Health Administration (MSHA) issued a final rule requiring that PDSs be installed on all continuous mining machines (CMMs) on the working section, with the exception of full-faced machines, according to a phase-in schedule for newly manufactured and existing equipment [1]. The PDSs that were designed for CMMs have since been adapted to other mobile machines. Mobile machines include scoops, which are used as general utility vehicles, as well as coal hauling machines, such as shuttle cars, ram cars, and continuous haulage systems. MSHA has examined all accident reports from 1984 to 2014, and determined that 42 fatalities could have been prevented on mobile machines had a PDS been installed [2]. As such, MSHA issued a proposed rule that would require mobile machines on working sections (with the exception of longwall sections) to be equipped with a PDS. This rule would follow a phase-in schedule for newly manufactured and existing equipment. Currently available PDSs are based on electromagnetic (EM) technology. NIOSH researchers developed a shell-based magnetic flux density distribution model [3] for determining the position of a miner near a machine. A typical system would consist of four generators positioned around the perimeter of the machine. Each generator is a coil of insulated wire wrapped around a ferrite core. The magnetic field strength is proportional to the current running through the coil. Miners working on the section have an MWC, which is a transceiver that measures the field strength emitted by the generators and transmits a data packet over an RF link which contains the field strength reading to the PDS controller mounted on the machine. The magnetic field generators are pulsed sequentially such that the MWC can identify which generator’s field strength it is reading. This type of system utilizes the principle of magnetic flux density: the closer the MWC is to the field generators, the higher the field strength reading. Thus a miner’s presence can be determined once he gets too close to the machine, because his MWC will measure a magnetic flux density beyond a certain threshold. These thresholds are utilized on a per-generator basis to “shape” the fields for both warning and stop zones around a machine, as illustrated in Figure 1."

Jan 1, 2017

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

By I. Orisek

The methodology and results of a feasibility study of an Automatic Truck Dispatching (ATD) system in an actual open pit mining operation, are presented. Using mine cost data, an economic analysis confirms that capital and operating cost savings with ATD out-weigh the costs. Productivity improvement achievable with ATD is quantified with a computer simulation of truck haulage based on mine production and operational data.

Jan 1, 1986

By J. O. Marsden

The Candelaria copper-gold mine is located approximately 25 km south and east of Copiapo in Region III, Chile. The original concentrator was designed to treat 28,000 t/d (30,800 stpd) of chalcopyrite-bearing ore through a circuit consisting of a single 11.0 m (36 ft) diameter SAG mill, two ball mills, conventional rougher and scavenger flotation, column cell cleaner flotation, and ceramic disc filtration. The plant was commissioned in August 1994 and quickly reached capacity and expected levels of metallurgical performance. In May 1996, a decision was made to double the capacity of the concentrator by the addition of a second line of equipment. The expanded facilities were commissioned in October 1997, less than 18 months after the decision to proceed, and well within the budget. The original concentrator facilities were replicated or duplicated as much as possible, however, a number of important equipment changes were made to take advantage of industry developments since the original concentrator was designed. These included the use of Eimco 120 m3 (4,200 ft3) cells for rougher and scavenger flotation and the installation of a Svedala VTM -800 Vertimill for regrinding. This paper describes the rationale behind these changes and explores the reasons for the success of the project.

Jan 1, 1999

By John A. Sievert

Sedimentary deposits contain an appreciable portion of the world's supply of uranium. Predictions of nuclear fuel usage in the United States indicate that these reserves will have to be tapped if the domestic industry is to be the major supplier of fuels for the nuclear reactors. Techniques developed within the petroleum industry are a base on which to build economically attractive fluid mining processes for the recovery of these uranium values. The problems central to the success of such mining processes are the containment, control, and recovery of a narrow band of pregnant leach solution as it progresses from the point of injection to the point of production Given sufficient incentive, suitable solutions to these problems can be found

Jan 1, 1970

By C. A. Rowland

Autogenous grinding, defined as grinding with like material, while quite an old art has recently been revitalized. Two phases of autogenous grinding, primary and secondary, have been the subject of recent papers, technical articles and discussions. The purpose of this paper is to discuss a third phase of autogenous grinding - Intermediate Autogenous Grinding - comparing it to and indicating advantages over the other two phases. Autogenous grinding can also be called ?Rock grinding?1; that is, grinding using ore or rock from the same deposit as the mill feed as grinding media contrasted with using as grinding media steel rods, steel or ironballs, natural or manufactured iron, free pebbles, or other shapes and materials foreign to the mill feed.

Jan 1, 1964

By D. E. Cameron

"INTRODUCTION Grade control requirements for base and precious metal projects are an important input to both conceptual and feasibility mine plans. It’s the author’s experience that grade control input is insufficient at these critical stages. The few exceptions are a stimulus for this paper. A significant portion of CRC’s practice has involved assisting operations to solve grade control issues which were finally recognized as contributing to negative production variances. Even in operations perceived to be successful, deficiencies in grade control are often masked by measures taken by an operation to compensate a deficiency in one area with outperformance in another. The advantages in having a realistic and adequate grade control plan developed at an early project stage by a geologist(s) with considerable operations experience are manifold. It’s important for the geologist to prepare clear inputs into the mine plan backed by detailed supporting information in usable, flexible formats. When the decision is made to advance a project, the exploration team passes its model to a mine planner. The team doesn’t usually provide a detailed grade control plan with the block model, thus the planner tends to treat grade control as an activity to be rolled into a broader operating category. The consequences of highly compartmentalized mine planning can be severe in the long run. Once a plan is tabled, and especially once production begins, it is very difficult to improve grade control outside the fixed parameters of the operation. Major fixes tend to be costly in terms of time and dollars. Implementing needed changes to the grade control practices and culture in an established mine can present almost insurmountable difficulties. Hypothetical examples of grade control planning are presented to illustrate the author’s points. The diagrams are conceptual and schematic; any resemblance to actual deposits is coincidental. BEYOND 50¢/TON In more than a few cases, grade control cost is buried in a subcategory of mining cost with little more consideration than a plugged number. It is possible to do a word search in 43-101 Technical Reports on advanced projects and without finding reference to “ore control” or “grade control”. The idea is to reach the orebody by the shortest and least expensive means, achieving production and investor payback at the earliest possible occasion. This entails a low stripping ratio pit or a decline ramp with sills on ore to prepare the first stopes. The processes to achieve the target production, one of which is grade control, will fit into this framework. After all, there is a block model and the planner can see the grade and tons in each block. The exploration geologist whose responsibility was to bring a large percentage of the deposit into mineral resource owns the model and has released it to planning. Now comes the planning stage. Mine geologists haven’t been hired yet and they will be phased in with production. What could go wrong? Larger companies may have the geologists with operating depth who will be inserted into the mine planning discussions, but it’s not a given. Junior companies must often delegate the conceptual and detailed planning tasks to consultant groups. Is a senior-level grade control review part of the scope of work for the mine planning? If a good grade control plan is in place before the mine geology team is staffed, a key element of success is assured."

Jan 1, 2018

By T. Stack, C. Roos, M. Drake, P. Conrad

"This paper presents the evaluation Montana Tech completed for the Western Energy Company Rosebud Mine relating to the benefits of survey data collected using novel technologies over traditional methods for topographic surveys. These technologies include Unmanned Aircraft Systems (UAS), photogrammetry, and laser scanning/LIDAR. Utilizing these technologies, large areas such as reclamation areas and cast blasts can be surveyed in a timely manner for use by the mining operation. The areas that were evaluated were the improvements in the safety of employees and the time required to collect data. In addition, there is also a potential cost savings for the operation, all while not affecting the accuracy of the data that is collected. PROJECT BACKGROUND Accurate topographic survey data is critical to successful surface mining operations. It is used for mine planning and design as well as permit compliance. Currently, employees typically collect survey data using GPS equipment or total stations. These methods can be dangerous, as they require employees to work near large operating mobile equipment, edge of high walls, and on piles of stacked steep-sloped loose material. Aerial and satellite photographs, performed by a contractor, can be used to obtain some of this information, but it is expensive and may not be attainable during overcast conditions. Montana Tech, along with the Rosebud Mine, conducted research on the accuracy, cost, and other benefits of survey data collected using novel technologies. Some of the methods studied include, but are not limited to, Unmanned Aerial Systems (UAS) or Vehicles (UAV), photogrammetry, and laser scanning. These methods were evaluated to determine if these technologies provide mining companies with a safer, cost effective, and accurate method to collect data for surface mining operations. The project scope was to evaluate various surveying techniques to determine which techniques would be applicable for the Rosebud Mine and complete a trade-off study comparing the new techniques with currently used methods. The trade-off study included an analysis of the technological differences between the methods, safety and legal considerations for the new techniques, operational limits, and the costs associated with each technique. Working with the Rosebud Mine team, techniques were selected for field trial and accuracy comparison. This paper presents a literature review of applicable technical papers and a summary of the Federal Aviation Administration regulations for UAS, followed by a study comparing conventional GPS topographic surveys with UAS based systems and laser scanning systems. The comparison of the various methods was broken into the following four categories: operator safety analysis, time comparison, survey accuracy, and cost analysis. After all of these portions of comparison were completed a recommendation was provided based on the evaluation that was performed."

Jan 1, 2017

By William W. Leathen

Acid mine drainage became a reality through the exposure of the first bituminous coal seam, either by man or by nature. At first the small amount of acid formed was quickly and efficiently neutralized by basic rock strata and by neutral or alkaline water. As soon as extensive mining operations overtaxed nature's own defensive measures, acid mine drainage became a problem of concern to government and the coal industry. It was the purpose of the studies conducted at Mellon Institute to accumulate knowledge, both applied and fundamental, relating to the formation and disposal of acid mine effluents. It was during this program that the microbiology of acid mine water was studied. Most bituminous coal mine effluents are highly acidic and contain, along with other ions, high concentrations of ferrous iron. The acid is sulfuric, and. the iron is present as the sulfate; both are the oxidation products of iron sulfides (FeS2) which are present in the form of pyrites, marcasites, or other sulfuritic minerals. The oxidation occurs, in the absence of moisture, according to the following reaction: [ ]

Jan 1, 1959

By T. D. Kaufmann

When Dr. David Gully solicited this paper last spring a few questions basic to commodity trade between the U.S. and world markets appeared perplexing. Why, for example, when the demand for aluminum was at a peak and when little expansion of capacity had taken place, was the dollar price half of what it had been at the previous peak? Or, why in 1984 when imports surged by 50% as the U.S. economy pulled out of its recession did the dollar not fall, but rather rose by 35%? And, why when the experts all seemed to agree that the dollar was grossly overvalued did the price of gold continue to decline? Surely these were extraordinary times for the mineral economist. When this paper was written in late July, 1985 the answers seemed clearer. The prices of many commodities were not low - the dollar in which they were denominated was too high. In other currencies many commodity prices were indeed high. The dollar was overvalued in trade terms by some 40% caused by an influx of short term coupon investments made by foreign money managers to take advantage of the higher short term interest rates in the U.S. relative to other international banking centers. With a decline in the relative difference in interest rates, an unhealthy buildup of foreign bank accounts and a perception that the dollar would fall, the dollar did start to decline rapidly.

Jan 1, 1985

By F. L. Pirkle

The mineral zircon is mined for use as specialty foundry sands, abrasives, ores of ZrO2 and zirconium metal, refractories, and zirconium chemicals. It is produced as one of several products from heavy-mineral sand deposits associated with fossil shorelines. Because of its low coefficient of thermal expansion, its high melting point, its high refractive index, and its chemical inertness, it is an attractive refractory material. Zircon varies from deposit to deposit in terms of grain size, grain shape, and chemical impurity. Thus, there is a wide range of commercial products differing in impurity levels, particle shapes, and grain sizes.

Jan 1, 1992