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By Thomas G. Hayes

Track-type tractors remain one of the most cost-efficient stripping tools available to coal miners. Whether they are "sweetening up" a dragline operation with prebenching or serving as the primary tool, dozers are important in driving down mining costs. This article reviews the application zone of track-type dozers. It also provides suggestions for site setup, equipping tractors and machine operation. In recent years, the track-type tractor has become more of a production tool in mining. With the advent of bigger machines, bulldozers have become a typical component in mining operations, removing overburden down to the top seam of coal. Large tractors can also be teamed up with draglines and other systems to maximize the effectiveness of the mining system. Bulldozers remain the tool of choice for topsoil removal, spoil reclamation or any application that demands low ground pressure, or short distance. The introduction of the 523-kW (700-hp) track-type tractor to the mining industry has made the bulldozer a low-cost-per-ton means of removing overburden. The large tractors offer enough productive capability to be considered prime stripping tools. And they can lower mining costs by complementing other mining systems (dragline, cast blasting and loader/truck). Four criteria determine whether a track-type tractor is the right machine for a particular application: ? Production requirements - dozer may fit job requirements better than a second dragline. [ ] ? Product support - availability of parts, service and technical expertise. ? Labor situation - how much of the cost per ton goes to the operator. ? Resale opportunity - recover a percentage of capital cost. Mining efficiency is economically controlling the cost of any system. Most operations rate the most economical means of moving material as cast blasting, dragline and the track-type tractor. All three of these systems share one common value: They are all sensitive to distance. Regardless of the application, all mining systems have an economic range. Exceeding this distance will affect cost and productivity.

Jan 1, 1997

By Frank C. Appleyard

As the environmental movement gained force during the past few years, it was inevitable that attention would be focused on surface mining, and we have seen this method of extracting minerals from the ground come under heavy attack by conservation groups, the press and television, legislators at all levels of government,, and the public at large. It is difficult, and in some situations, perhaps impossible, to measure either the need for, or the results of, land reclamation in absolute terms. Therefore, much of the criticism of surface mining has been based upon subjective analysis rather than hard data, with the result that discussion of the subject often includes a fair amount of emotional response. To be fair, this reaction is not limited to just our critics; even we hard headed engineers sometimes respond in the same way, an observation with which you may agree when I finish this talk. This leads to the thought that whether you are for it, or against it, land reclamation in many respects is a state of mind. That is, our reaction to it can vary considerably, depending on how far we have thought it through. And think it through we must, because the pressures being brought to bear need to be met with positive actions if the problem is to be brought under control, and in the next few minutes I would like to discuss from a management point of view some ideas which might aid in this thinking process. It would be a mistake, I believe, to think that the current energy crisis will suddenly bring the environmental movement to a stop, and therefore, we can relax and go back to running our busi¬ness the way we used to. This is not realistic; on the contrary the energy crisis is focusing attention on the limitations of our natural resources as nothing else could, and with respect to land

Jan 1, 1974

By Ali Ekrem Aritan

In this study, the vibration exposure of excavator operators working regularly in 25 different natural-stone quarries was measured. In addition, the relationship between vibration exposure and rock properties was investigated. Gloved and ungloved vibration measurements were performed and revealed that antivibration gloves reduce excavator operators’ vibration exposure by 7.10 to 25.95 percent. Samples from each quarry were characterized with rock mechanics tests. The correlations between the hand-arm vibration measurements and the natural stone’s physical-mechanical properties, such as uniaxial compressive strength, Shore hardness, Knoop hardness, apparent density and total porosity were determined to be more than 70 percent. One finding of the study was that the health risk in excavators cannot be reduced sufficiently by the sole use of antivibration gloves. Furthermore, the excavation of any rock with a Knoop hardness above 121 is associated with an 81 percent risk of hand-arm vibration. To increase awareness of the danger of vibration exposure for natural-stone miners, training programs should be provided, and technical and operational changes should be implemented.

By V. F. Hollister

Although it is apparent that porphyry copper deposits may have formed in the Andean orogen from Permian time onward, commercial deposits thus far developed appear to have Cenozoic ages only. Following Chilean useage, the porphyry deposits are divided into either: (a) a stockwork, or (b) a tourmaline breccia model. Stockwork type deposits tend to occur on major strike-slip structures which may be either transcurrent or transverse faults related to plate movements, while the tourmaline breccia type may more frequently form independently of regional faults. Stockwork types may be conjugate fractures that intersect and ramify as a network of veins and veinlets, cutting altered rock, and genetically related to a major regional fault, or in other cases they may reflect the intersection of two large fault structures. Circular fracture patterns may more rarely occur in stockwork deposits in response to a specific intrusive. Tourmaline breccia types are characterized by circular and radial fractures genetically connected in some way with tourmaline breccia pipe development or an intrusive piercement that preceded it. Each structural model contains mineralized intrusive8 which have a close time-space relationship to ore and in each model, mineral paragenesis is similar, regardless of age or location in the plate. Also, each model contains the same type of alterntion halos (phyllic, argillic, prophllitic) as are developed in intru- sive centers in porphyry copper deposits found in North America. The potassic zone is exposed best in the older deposits. Examples of each type of deposit are illustrated, demonstrating the feature evolved.

Jan 1, 1973

By Stephen G. Hardcastle, Michel G. Grenier, Kevin C. Butler

Today there are numerous electronic rotating vane and thermal (hot-wire) anemometers, as well as vortex meters available to measure air velocity. Of these, a laboratory and field evaluation has found that certain instruments are better suited to routine airflow measurements in mine roadways and ventilation ducts. This paper concludes a study sponsored by the Atomic Energy Control Board of Canada, that was introduced at the 5th U.S. Symposium. The study investigated the suitability of currently available electronic anemometers as replacements for the traditional mechanical analog devices while maintaining standard methods such as the continuous traverse. Six electronic instruments were subjected to extensive tests under controlled conditions both in a wind-tunnel and in the field at an underground mine. The evaluation concluded that ergonomics and design were major considerations in unit preference as most of the instruments had very similar performance characteristics. Specific findings were: a) In the wind-tunnel the vane anemometers, especially the "micro" vanes, were more susceptible to misalignment or yaw effects but these were not noticeable in the field; b) Both the vortex and hot-wire anemometers were suitable for continuous traverses of mine roadways; c) Traversing ventilation ducts was more practical than a Pitot-tube multi-point assessments or discharge measurements; d) Yaw is a major concern in duct measurements; e) The continuous traversing method for roadways overestimates the average air velocity; f) Hot-wire anemometers can require significant air density corrections; and g) Hot-wire anemometers are better suited than rotating vanes to mine roadways of less than 1 m/s average air velocity. Based on research detailed in this paper, the ventilation engineer should be able to match the mine's requirements with the presented instrument performance characteristics, thereby optimizing the purchase of a new anemometer and the efficiency with which air velocities are measured.

Jan 1, 1993

By W. R. Boehme

The test work was done in two parts. In Part I, five 6 x 16 mesh activated coconut shell carbon samples made by four different manufacturers were evaluated as to their gold loading rate and total gold loading. The five carbon samples tested are not identified by manufacturer and are simply designated as Types A through E. Then from the carbons tested, a suitable highly active carbon was selected for subsequent studies on impurity effects upon loading, Part II. Test Procedures The procedures and tests descriptions are given for the ultimate gold carbon loading tests and the dynamic gold carbon loading tests.

Jan 1, 1983

By O. J. R. Baena, N. J. Zapata

In Colombia, more than 15 regions and around 100 municipalities develop gold mining at different scales, and these operations generate mining waste composed of processing fluids and crushed rock with metals and high silica content. Cement production requires clinker, gypsum and other corrective additives. Clinker results from the partial fusion of some minerals including silica. In this study is proposed to evaluate the effect of the use of mining tailings sands from gold mining in the manufacture of clinker. The proposed methodology will allow the characterization of the sands to manufacture a cement specimen and measure its physical and fire properties

Mar 2, 2022

By J. Philip Bromberg

The 1977 Clean Air Act Amendments will have a large effect on the coal-fired segment of the electric utility industry. Since electric power generation constitutes by far the largest single use for coal, this legislation has the potential to greatly affect future patterns of coal utilization in the U.S.A. The inability to depend exclusively upon low sulfur coal as an exclusive mode of compliance with New Source Performance Standards may greatly lessen projected demands for low sulfur coal by eastern utility boilers. The requirements of the legislation is discussed with particular reference to the needs of the electric generating industry, along with the technologies available for complying with the Act.

Jan 1, 1978

By V. F. Swanson

A mathematical model is presented which allows the free or hindered settling velocity to he calculated for any size or- shape particle in any fluid, and at any percent solids up to the maximum. The validity of the model is supported by comparing calculated velocities (or viscosities) with measured values for 1073 data points contained in 80 sets of data encompassing a range of Reynolds’ numbers, from 0.002 to 770.000. The average error was 0.69%, with an average standard deviation of 6.65%. The derivation of the model is too lengthy to include in this paper, which will specifically present the application of the model to the free settling of minerals and spheres, prediction of the friction factor in wind tunnel tests, the viscosity of suspensions of spheres, the hindered settling of mono-sized spheres and closely sized minerals, and the settling of large spheres in suspensions of small spheres.

Jan 1, 1990

By R. Rodgers

The Pinto Valley Concentrator of BHP Copper Inc. restarted its sulphide mining operations in September 2007 to produce copper and moly concentrates. During the plant production ramp up, the copper/moly circuit quickly reached the copper grade and recovery targets, but the production and quality of the moly concentrate continued to be a challenge. Even though several improvements in the moly circuit were completed, the final moly concentrate did not meet contractual specifications. After reviewing several options to improve grade and reduce contaminants, the installation of three flotation columns was chosen. The column design and construction were done utilizing in-house craftsmen and engineers. Ten days after commissioning, the columns successfully reached a steady operation and began producing moly concentrate to the required specifications, that is, high moly tenors and low copper and iron content. In this paper, the operating parameters, mass balance, design, installation, commissioning and operation of the new flotation columns will be discussed.

Jan 1, 2010

By R. V. Ramani

In this paper, the application of the concepts of reliability engineering to the evaluation of longwall system performance is illustrated with data from an operating longwall face. A number of cases are analyzed to highlight the impacts of longwall equipment, geological conditions and outby haulage on systems reliability and availability.

Jan 1, 1988

By Jr. Matthews

The Candelaria copper-gold deposit is located in Region m of Chile, 805 kilometers north of the capital, Santiago. Candelaria was discovered in 1987, following a six month exploration program. In late 1986, induced polarization (IP) surveys outlined an anomalously high response within the area of interest. The first test hole bad three intersections totaling 49 meters, with an average grade of 1.97% copper. Drilling eventually outlined approximately 390 million tonnes, grading 1.09010 copper and 0.26 grams/tonne gold. Production began in early 1995 and is estimated at 120,000 tonnes copper and 80,000 ounces gold annually.

Jan 1, 1996

By James J. Scott

In 1910 the United States Bureau of Mines was created. It was the outgrowth of a social problem stemming from the fact that 25,000 men were killed in coal mining accidents for the period 1900-1910. Something had to be done and congress responded to the people's demands by creation of this new regulatory agency. At that time mine operators felt the new agency was too strict but nonetheless new rules were developed and enforced and results were obtained by the industry which reduced fatal accidents to less than 250 per year by 1970.*Social reaction by the general public brought about legislation which created the Federal Coal Mine Health and Safety Act of 1969 This legislation was a direct reaction to the Farmington Disaster. Operators and miners alike said "we cannot operate under this law. It is too strict, requirements are unrealistic, production will suffer, .there will not be any improvement in health and safety, etc." Consider the facts: 1. Health and safety have improved. The 1972 frequency and severity rate was the best ever for the bituminous coal mining industry, Figure 1. 2 .Production per manshift has dropped in underground coal mines. For example, in West Virginia from near 16 tons/m.s. in 1967 to nearly 11 tons/m.s. in 1971-72. However, not all of this loss can be attributable to the Act, but certainly some is. (2) The betterment of the safety of coal mining was a prime motivation behind the coal law and from that standpoint the law has been partially successful, but the loss in productivity has been a real burden to the mine operator. Everyone should recognize that the law says little in regard to production--it only relates to health and safety. Production is management's responsibility.

Jan 1, 1973

By S. A. Tims

INTRODUCTION The Falconbridge mine ore body extends about 1.6 km (1 mile) in length and the deepest developed ore is on the 6050 level below surface. The ore zone varies in width from a few inches to over 30 m (100 ft) and the average width is 4.9 m (16 ft). Access levels are driven in the ore at 53.3-m (175-ft) intervals. The principal method of mining is overhand longitudinal cut-¬and-fill. Prior to 1962 timber square-set stoping as a secondary extraction method was used for about 15% of the total production. Undercut-and-fill was intro¬duced at Falconbridge in 1962 as a potential replace¬ment for the square-set method in heavy ground. The undercut-and-fill method was developed by Inco in the 1950s, its principal application being to transverse pillar mining. Falconbridge made modifications to this method. A feature of the mine is the No. 1 flat fault which dips 0.79 rad (45°) towards the northeast. The main characteristic of the fault is the presence of large swells of ore directly under the plane of the fault. The ground under the fault area is highly fractured and associated with massive sulfides. In the past, the ore under the fault was recovered, with difficulty, by either tight cut¬and-fill or square-set stoping. In the 1970s these meth¬ods were supplanted to a large degree by the under-cut-¬and-fill method. An advantage of the current undercut-and-fill method which uses cemented fill compared to the cut-and-fill and square-set methods is the reduction of dilution due to better control of the walls. At Falconbridge mine, it is estimated that the grade of ore produced by undercut¬and-fill is improved by approximately 10% over other methods. Where undercut-and-fill is used in very weak ground, a much greater improvement in grade can be expected. Table I shows mining production for 1974. The undercut-and-fill method was first used at Falconbridge during 1962. The first longitudinal stope was prepared for undercutting by laying down laminated beams the length of the stope and installing a lagging mat floor on top of the beams. Unconsolidated tailings fill was poured on top of the mat floor. As the cut ad¬vanced under the floor, heavy posts were placed under the laminated beams at 1.8-m (6-ft) intervals. During 1966, a radical change was made to the method when tailings fill, consolidated with portland cement, replaced the unconsolidated fill. This development eliminated the laminated beams and heavy mat floor and greatly im¬proved the stability of the stope. This system, with minor variations, is currently used at Falconbridge mine. APPLICATION The undercut-and-fill method is used to mine in¬competent ground, sills or floor pillars under mined-out levels, or a block of ore isolated between levels. It is occasionally used to advantage in sequencing produc¬tion from various mining blocks. This is done by mining a block of ore cut-and-fill method and at the same time mining the ore block directly underneath by the under¬cut-and-fill method. The undercut-and-fill mill holes at Falconbridge are either boreholes, stripped timbered raises, or steel mill holes. Boreholes and rock raises tend to slough in heavy and broken ground which increases dilution when sloughing exceeds the ore width outline and also in¬creases the difficulty of moving down to start the new cut. For example, in one installation, a 1.2-m (4-ft) diam borehole sloughed to a size of 3.7 x 5.5 m (12 x 18 ft). The undercut-and-fill method usually requires a mill hole extending from the level below the ore to the top horizon of the ore block. The customary methods of providing a mill hole are: 1) A borehole is driven from level to level through the ore block and a chute installed on the bottom level (Fig. 1). 2) An existing raise is used as a mill hole. If the raise is timbered, a steel mill hole is installed inside the timber and tailings fill poured around the steel mill hole (Fig. 1). 3) An existing steel mill hole, situated at one end of a mined-out stope, is used as the mill hole for an ad¬jacent undercut-and-fill ore block. The mill hole posi¬tion is determined when planning the mining sequence of the first stope (Fig. 2).

Jan 1, 1982

By Dermot M. Ross-Brown

The objectives of this generic study were to use numerical modeling techniques to determine under what conditions seismic waves generated by an earthquake might cause instability to an underground opening, or cause fracturing and joint movement that would lead to an increase in the permeability of the rock mass. In general, the study showed that moderate earthquakes (up to 0.41 g) did not cause instability of the tunnel or major fracturing of the rock mass. An artificial rock-burst tremor with high accelerations, however, was found to be amplified around the tunnel, and fracturing occurred as a result of the seismic loading in salt and granite. In shale, even moderate seismic loading resulted in tunnel collapse.

Jan 1, 1981

By Y. J. Wang

A critical path approach is presented for the problem of mine ventilation net- works where regulators and fans are employed to control the airflow distribution which is preassigned. The problem is a classic one which arises in mine ventilation planning. By identifying the analogy between the network for controlled flow and that for CPPI, the applications of the well known CPM technique to the ventilation network problem become straight- forward. The mathematical formulation of the problem is presented and the solutions are illustrated with examples. The effect of booster fans on the total air power consumed in a ventilation network are also discussed.

Jan 1, 1981

By Irwan Halim, Bhoshaga Mitrran Ravi Chandran, Kevin Huynh

Tunnel segmental lining design constitutes a significant iterative process where modeling and numerical analysis are factors in deciding the number of segments, their dimensions, gasket placements, as well as the locations of dowels and bolts. Consequently, these modifications lead to revisions in the final drawing details. However, the current tunnel engineering practices lack systematic solutions that effectively bridge the gap between the iterative design process and efficient visualization of completed drawings due to the time- consuming nature of redrawing. This paper presents a pioneering application of AI-driven solutions including using Autodesk's API, for the Northside Interceptor Tunnel (NSIT) Project. It showcases the automation of drawing design and the real-time visualization of modifications, thereby streamlining the drawing process.

Jun 23, 2024

By P. N. Bradbury

The coal companies of today have to make all of their in-the-field managers MAINTENANCE PRODUCTION MANAGERS. By using a computer application to monitor all aspects of the daily production as well as the maintenance, a company can immediately effect a cost reduction by studying the down-time and delay trends on an everyday basis. This paper will outline how a company can use a program to not only put a stop to the increasing supply and maintenance costs but start trimming each of these cost centers while actually increasing the efficiency and productivity of the current work force.

Jan 1, 1991

By Robert M. Dreyer

The first time that a geologist is confronted with the necessity of evaluating a lateritic ore deposit, he may feel that nothing could be easier. Why should there be any problems in making an economic evaluation of a relatively flat-lying, surficial ore body? After several hundred thousand dollars worth of frustrating work often culminating in a series of non-reproducible data - the evaluator may be a sadder and wiser man. This paper will try to illustrate why the evaluation of lateritic bauxite and nickel deposits is among the most difficult problems confronting an economic geologist - and, more especially, how this problem can be solved. Volumes have been published on descriptive and genetic studies of lateritic ores. Obviously, there is time today only for the briefest description of such an ore body. The laterite is a soil formed under tropical conditions and resulting in the concentration, within the soil zone, of certain tri-valent metals.- especially, aluminum and nickel. The soil zone is divided into two parts: (a) the true soil or lateritic zone and (b) the zone of, partially altered bed rock or saprolite. It is important to remember that, whereas bauxite generally is confined to the laterite zone, nickel deposits occur in both the laterite and

Jan 1, 1977

By M. A. Trevits, G. W. Luxbacher, L. D. Patts

"It is almost a given that post-disaster mine conditions will have compromised the mine ventilation system, resulting in a hazardous atmosphere in portions of the mine, and often complicated travel through debris fields and roof falls. Robotic technologies provide the opportunity to gather valuable information to assist decision making or lessen exposure to dangerous conditions. MSHA's Mine Emergency Operations Division (MEO) has utilized a fully permissible mine robot, the V2, for a number of years, constantly updating the unit as new technologies became available. The National Institute for Occupational Safety and Health, as part of the MINER Act Extramural Contract Program, examined the need for additional robotic units and ultimately funded three different types of prototype technologies: two robots, the Snake Robot and the Gemini-Scout, and a mine rescue robotic assist vehicle known as the ""Mule"". The Snake Robot is designed to be lowered through a borehole and to conduct surveillance (gas monitoring, video and audio) in the immediate vicinity, while the Gemini-Scout, designed to be deployed in the mine opening, serves as a more mobile and agile exploratory tool as compared to the MSHA V2 robot. The Mule was developed in response to needs expressed by mine rescue teams for a versatile remotely operated support vehicle and it will move from prototype to MEO utilization in the near future. This paper describes the development of the robot prototypes and discusses their limitations in the prototype stage, possible enhancements and potential applications, as well as the utilization of the Mule. INTRODUCTION The conditions in a coal mine may be dramatically altered after a mine fire or explosion. For example, the ventilation system may not be functioning correctly as control devices may be compromised or damaged beyond repair. The visibility in the mine opening may be limited due to accumulated smoke and dust. Roof support systems may be damaged or no longer functional. Equipment and materials may be strewn about the mine opening. Debris fields, blocked openings, roof falls, flooded areas, gas accumulations and active burning make it very difficult or impossible for those managing the post-event emergency to permit mine rescue teams to enter the mine to conduct search and rescue operations. With the evolution of robots and robotic assist technology there has been a proliferation of purpose-built units for the military, police and law enforcement agencies, urban search and rescue and those contending with hazardous environmental conditions. In each case, the technology used is designed to limit human exposure to the unsafe conditions or to provide access to areas under difficult conditions. For example, a specially-designed marine robot has been deployed into the damaged core of the Japan’s Fukushima Daiichi Nuclear Power Plant to assess the conditions of the containment vessels, where melted fuel is believed to have accumulated. Human access to the area is prohibited due to dangerously elevated levels of radioactivity [1]. Multiple robots were deployed in Amatrice, Italy, to assist in the response after the 6.2-magnitude earthquake devastated the town. The robots were used to explore two medieval churches that were severely damaged and deemed too dangerous for human entry [2]. Tactical robots are regularly used by police and law enforcement agencies when the conditions of the emergency place intervening officers directly in harm's way [3]."

Jan 1, 2018