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By L. Barry Phelps

The complexity of surface mining operations is increasing as attention is directed towards mining larger tracts of lower grade, higher cost deposits. Large tonnage requirements from these mines necessitate utilization of many large pieces of equipment. This equipment must be utilized efficiently, with production maintained at or near designed capacities. Basically, the problem is to select, size, and schedule equipment to maximize profits and minimize adverse environmental impacts (Anon., 1977). The time, manpower, and cost limitations required to analyze a wide variety of situations and alternatives in planning surface mines have been sidestepped with the application of simulation methods using a digital computer. Since a simulator can be programmed to represent the situations which are to be analyzed, many alternatives can be evaluated in a relatively short time. Input variables are easily changed and the resulting changes which take place in the system can be analyzed. When standard methods of analyses are applied, weeks and many man-hours are involved in analyzing large-scale mining operations. At the same time many simplifying assumptions must be made since these operations are dynamic and transient. Hence, it becomes difficult to make sound engineering decisions and take proper and timely corrective action in the absence of simulation methods. This chapter is concerned with the application of one such method, namely, the open-pit materials handling simulator (OPMHS) developed by the Mining Engineering Section, The Pennsylvania State University (Manula, Albert, and Ramani, 1977).

Jan 1, 1979

By P. Somasundaran, Brij M. Moudgil

All the major interfacial technologies encountered in mineral processing involve adsorption of surfactants and/or polymers. With the need for processing low grade complex ores it is imperative that conventional techniques such as flotation and flocculation be extended to meet the challenge of treatment of fines. Addition of surfactants or polymers is indeed not limited to the solid-solid separations but extends to particle size reduction in the form of grinding aids and dewatering operations as well. Although progress has been made in recent years to understand the science involved in various interfacial processes, more challenges and opportunities exist today than ever before in processing of the low grade finely disseminated ores. A brief review of the recent advances and the challenges in mineral processing, especially, those related to the interfacial technologies is presented.

Jan 1, 1989

By M. J. Laurila

Elemental analysis of slurry streams using X-ray fluorescence (XRF) has long been employed. However, detector technology has limited the application of XRF devices. Using detector technology employed on NASA's Mars Pathfinder to analyze soil samples, Process Control, Inc. has developed an on-line analyzer to mount on a sampling system. The prototype XRF elemental analyzer was installed at Detroit Edison's Monroe Power Plant in January, 1998 and has been employed to monitor feedstock quality. A slurry system has been developed for flotation control. This paper describes the testing of the analyzer using the new, draft ISO standard for evaluating the performance of on-line analyzers (ISO/DIS 15239).

Jan 1, 1999

By F. F. Aplan

Rather than reiterate what is well known about the flotation of the non-sulfide minerals, emphasis has been placed on those separations which are not so effective. These difficult separations are largely connected with problems of selectivity in the flotation of the base metal oxides, the other slightly soluble minerals, the insoluble oxides and the naturally floatable minerals. The paper discusses possible methods of improving selectivity between similar species and of improving selectivity against the gangue minerals.

Jan 1, 1994

By Edward M. Dowey

This paper presents the excavation of the Roosevelt Island Valve Chamber, the final of three chambers in Stage One of New York City's Third Water Tunnel. The valve chamber and passageways 13 379.7 cu m (17 500 cu yd) are drilled and blasted. The rock is stabilized by grouted rock anchors. The 6.1 m (20 ft) diameter shaft is drilled, blasted, rock bolted and wire meshed for a depth of 70.7 m (232 ft). Then shaft excavation proceeds with immediate concrete lining for another 120.7 m (396 ft). Two 6.1m (20 ft) diameter manifolds are excavated using heading and bench. The raise drilling of eight 3.7 m (12 ft) diameter laterals occurs during lower shaft sinking.

Jan 1, 1987

By Otis M. Clarke

Domestic bauxite used in aluminum production comes from Arkansas where syenite was lateritized forming bauxite. Part of the residual bauxite and kaolinized syenite were eroded, deposited downdip, lateritized with bauxite formed in place, and covered by sediments. The unconsolidated overburden causes problems in mining. Bauxite for refractories and chemicals comes from Alabama and Georgia. Sediments were deposited in karst lakes and were lateritized forming bauxite and kaolin. Ferruginous bauxite in Washington, Oregon and Hawaii, derived from weathered basalt, can be used in aluminum production.

Jan 1, 1984

By R. Larry Davis

Over the past decade there has been a continual decrease in domestic oil reserves accompanied by a sharp increase in the demand for energy. Even with increased imports of foreign oil, the energy demand has not been met. This has forced many users to turn to substitute fuels. Of the many substitute fuels available most users are turning to and creating an increased demand for low sulfur coal. Because of the increased demand for low sulfur coal as well as the inherent problems in producing eastern coal, many producers have turned their attention to the large deposits of low sulfur coal in the western United States. Western coal mining is, however, not without its problems such as high moisture content, high ash content, highly variable sulfur content, multiple seams, and/or pitching seams. It is to aid in the solution of these problems that this chapter is directed.

Jan 1, 1979

By D. W. Wu, M. T. Haque

A novel impedance probe was commissioned specifically for capturing fast dynamic information about filtration processes. It provides an attractive alternative to more complex measurement techniques in situations where the slurry system is primarily one-dimensional. The probe can monitor mudline, slurry densification and drainage. Dynamic variations in cake permeability are obtained by combining dynamic mudline information obtained with the probe and filtrate rate data derived from a leaf test apparatus. The measurements are reviewed in relation to micro structural measurements obtained on iron ore filter cakes. The practical significance of these measurements for optimization of the filtration process is discussed.

Jan 1, 2002

By M. B. Díaz Aguado

Traditionally, the practical evaluation of a mining project for a potential investment has been made considering mainly technical aspects. But the concept of sustainable development has introduced significant changes in the factors analyzed to make the final decision. This paper proposes an empirical evaluation of a project considering not only technical, economic and financial parameters, but also associated risks and other intangible aspects, such as political considerations, stability in the legal frame, social factors and environmental issues. The proposed methodology is practical and easy to apply for project management. Among its main advantages, the following could be quoted: using this evaluation two different projects or locations of a same project can be compared, future behaviors could be predicted, the index incorporates a new approach to specific mining projects and this perspective could also be applied to other projects with environmental and social impact, such as civil works or industrial projects.

Jan 1, 2007

By Jacob Carr, Chenming Zhou, Nicholas Damiano, James Noll, Jingcheng Li

Machine-related injuries are one of the major safety concerns in underground coal mines. Severe injuries and fatalities occur when a miner is struck, crushed, or pinned by mining equipment such as a continuous mining machine (CMM), shuttle car, or a scoop. Proximity detection systems (PDSs) have been applied in mining to reduce these types of injuries and fatalities. All of the PDSs that are currently approved by the Mine Safety and Health Administration (MSHA) for use in underground coal mines are magnetic-field based and could be affected by metallic objects such as trailing cables. Researchers from the National Institute for Occupational Safety and Health (NIOSH) investigated the influence of trailing cables on the performance of PDSs. In particular, the magnetic field coupled from proximity system generators to a de-energized trailing cable was characterized. The results show that significant energy can be coupled from the proximity system generators to a trailing cable when there is a closed loop in the cable. The effect on PDS performance from the magnetic field radiated around an energized trailing cable was also quantified for different current amplitudes in the cable. It is shown that the magnetic field caused by the electric current in the trailing cable mainly consists of a 60-Hz signal and its harmonics which causes little interference to the PDS. The results presented in this paper can help PDS manufacturers to design better systems that are more immune to these effects.

By Barbery G., A. Maachar, M. Bourassa

Laboratory testing for flotation circuit design is carried out on a routine basis in a large number of lab- oratories throughout the world. Usually a sample of ore, assumed to be characteristic of the material to be processed in a future plant, having a mass of the order of a few kilograms, is ground in a batch ball or rod mill, in the presence of water and some re- agents (for pH control, etc. .. ); after dilution to the adequate solid concentration, the resulting slurry is transferred into a laboratory batch flotation machine, having a volume which can vary from 0.5 to 8 10 -3m3. Various types of machines are in common use, manufactured by the same companies that market industrial size flotation machines. The operation of flotation in the laboratory is carried out by an experienced technician, who uses parameters such as impeller rotation speed, air flowrate addition, froth height, froth removal rate, in conjonction with reagent addition sequence, to "test" the ore. After flotation, the froth products ("concentrates"), and the solids remaining in the cell are filtered, dried, and analyzed for the various elements of interest. For flotation circuit design, a kinetic test is usually carried out, in which the froth products obtained at various times are collected to assess the time response of the ore in the laboratory machine with the combination of reagents used. Although this description is rather sketchy, it enables to outline some of the major difficulties in using laboratory data for flotation circuit design: 1. ore sample representatively 2. feed preparation procedure (laboratory compared to industrial scale) 3. laboratory procedures (type of ma- chine, type of operation, experimental errors. . . ) 4. flotation machine scale-up 5. flotation kinetic scale-up 6. flotation circuit design using laboratory data These various points will be discussed in the present paper, in order to stress the problem areas as well as possible solutions. ORE SAMPLE REPRESENTATIVITY It has been stated many times that one of the major problem in designing a flotation circuit is the representatively of the sample to be taken. Sampling of an ore body during prospection and evaluation is a specialized field, which has been progress in with the introduction of geostatistics. The application

Jan 1, 1986

By S. S. Peng, V. Z. Sun

One of the major concerns of ground control in a coal mine is the prevention of roof, pillar and floor failures of the mine entry. To better design and evaluate the stability of a mine entry within a certain level of confidence, a reliability approach is introduced. The advantage of using the reliability approach, rather than the conventional safety-factor (SF) method, is that it not only takes variability of both rock/coal properties and stress into consideration but also assesses the stability of each component and the mine entry as a whole. Therefore, it is anticipated that by using this approach the current ground-control technology in a coal mine will convey a better sense of confidence. The results of a case study show that there is a significant difference in mine entry stability between the current design method and the reliability approach.

Jan 1, 1999

By David G. Chedgy

Noise control is an important consideration in the design and operation of coal preparation plants. It is essential to understand and control noise sources to provide a safe environment for operating personnel. The average noise exposure levels in a typical coal preparation plant generally range between 95 and 100 db. An operator should not be exposed to noise levels of this magnitude for more than 4 and 2 hr, respectively, according to MSHA (Mine Safety and Health Administration) regulations. The major noise sources in a coal preparation plant include noise from impacting the inside surfaces of steel chutes, vibrating screens, coal crushers, pumps, motors, fans, and blowers. The magnitude of noise varies considerably from one situation to another. NOISE EXPOSURE IN COAL PREPARATION PLANTS Noise regulations established by the Occupational Safety and Health administration (OSHA) are accepted by MSHA relative to caal preparation plants. Fig. 14-43 shows a graph of the time of noise exposure in hours per day to which a worker can be exposed for each A-weighted sound level. According to this graph, a worker is permitted to spend 8 hr in a 90-db noise environment, but that time must be halved when the A-weighted sound level increases 5 db. The noise dosage a worker receives is determined by the ratio of the length of time the worker spends in a particular noise environment divided by the length of time he is permitted to spend in that environment. If the worker is exposed to several different sound levels, his total dosage would be the sum of each of the individual dosages. The equation for determining the dosage is: where C is the actual duration of exposure at a given steady state noise level and T is the noise exposure limit for the level present during the time C According to MSHA regulations, the dosage, D, should not exceed one (1) for any worker for a full day of work. As an example of typical plant noise levels, vibratory screens and crushers emanate noise levels in excess of 90 db at a distance of 3 ft (0.9 m) with no material flow. With material flow, noise level increases 1 to 10 db depending

Jan 1, 1991

By Georgios Kalamaras, Sebastiano Pelizza, Carlo Alessio

"This article describes, through the presentation of five cases-history, technological advances that the Authors together with Tunneling Contractors devised for coping with adverse geotechnical conditions. It is believed that by introducing these new elements in a method that has proven its value in Italy and abroad for the last 40 years, the umbrella arch method, due to its versatility and simplicity, can become a universal method for conventional tunneling in very poor ground conditions. After a description of common faults and mistakes in applying the method, 5 projects are presented which demonstrate that self-drilling pipes give excellent results in terms of performance a zero volume loss, while, function of the ground conditions the various grouting mixtures used, such as expansive jet-injected cement-base grouts and bi-component resins, extend the use of the umbrella-arch in variety of grounds even in presence of water-bearing lenses. The case-histories provide successful applications in different conditions.BASIC FEATURES OF UMBRELLA ARCH METHODThe umbrella arch method provides a short support of the tunnel vault just ahead of the excavation face. The method foresees the drilling and installation of peripheral, sub-horizontal steel pipes in the ground, followed by their grouting. The umbrella arch method is also known as forepoling, steel pipe umbrella, reinforced protective umbrella or simply “umbrella”. The umbrella arch method does not have a static function because the immediate stabilization of tunnel section is entrusted to the internal shell of steel ribs and shotcrete. The “umbrella” provides a pre-support of the excavation which has to be stable for an adequate length and duration permitting the installation of the next steel rib and shotcrete under conditions of safety (Figure 1).The umbrella-arch provides pre-reinforcement of poor ground around the tunnel perimeter in a simple and flexible manner that is adaptable to different ground conditions. In fact, it is possible to vary the number and length of pipes, the distance between them, their diameter and thickness as well as the overlapping length of two succeeding umbrella arches. The versatility of the umbrella arch technique allows its application to: clay deposits, granular alluvial deposits, moraine and debris materials even when containing large blocks, heavily jointed, foliated and tectonically disturbed rock masses."

Jan 1, 2016

By B. Fitch, E. J. Roberts

Definitions and Terminology Classification is defined within this section as the separation of solid particles into size or weight fractions or classes by differential settling through a fluid. It is usually thought of as a size separation, but is actually made on the basis of particle settling rate, and so is affected by any variations in particle density and shape. The fluid may be liquid (wet classification) or gas (dry or air classification). This section will treat only wet classification. There are two basic types of classification; pool and hydraulic. In pool classification a suspension of feed particles is fed into and out of a pool of some kind at such a rate that only part of them¬ the coarser and faster-settling part-has time to settle out. The remain¬der overflows as fines. In hydraulic classification the feed suspension is introduced into or above one or more columns or pockets through which water is rising at a controlled velocity. Coarse particles subside through the pockets and are removed through spigots. Those which settle slower than the rising velocity in any column or pocket are (at least ideally) prevented from subsiding and so must overflow. Hydraulic classifiers or sizers are capable of making far sharper sepa¬rations than pool classifiers. The force causing settling may be gravity, or alternatively may be from centrifugal acceleration as developed in a centrifuge or hydra cyclone. Two things are needed to characterize the separation produced by classification: first, the size, D„ or equivalently the screen mesh at which it is made; second the sharpness of separation. Separation size may be defined in various ways. In closed-circuit grinding it is commonly specified by some point in the overflow screen analysis: For example, 5% on 65 mesh. In other applications, notably

Jan 1, 1985

By J. Herbst, H. W. Kropholler, L. A. Cramer, E. T. Woodburn, J. C. A. Greene, G. Poling

A generalized mathematical structure is proposed whereby internal species mass flows within a flotation network are defined uniquely by a matrix of enhancement factors. An element of the enhancement factor matrix is defined as the ratio of the mass flow of that species leaving a given cell in the concentrate to the species mass flow leaving the same cell in the tailings. To predict the enhancement factors, knowledge of flotation kinetics effects is required. Recently experimental data has become available relating to the performance of industrial flotation circuits which indicate that the discrete or discrete-distributed kinetic schemes are capable of reasonably effective simulations. These simulations show the importance of including froth effects. The prediction of performance of networks from small-scale batch tests on flotation streams shows that the model for the froth phase used in the simulations does not scale-up well and that aeration effects are also difficult to predict. The network analysis should be useful in differential flotation of complex ores and it is disappointing in this context that little information on the kinetics of activation and depression is available.

Jan 1, 1976

By F. C. Loughnan, Shane B. Sadleir

Bauxite is currently produced at three centres in Australia: - Weipa in northern Queensland; Gove on the northeastern tip of Northern Territory; and in the Darling Range near Perth, Western Australia. At each of these centres the bauxite is of Tertiary age and occurs as blanket-like, lateritic crusts in which gibbsite is the predominant mineral. Development was essentially in situ although possibly the deposits, particularly at Gove, are in part of transported origin. All of the deposits formed from quartz-rich parent rocks with those at Weipa and Gove being derived from kaolinitic sands while in the Darling Range, granite and other crystalline rocks of Precambrian age immediately underline the lateritic bauxite.

Jan 1, 1984

By Jamal Rostami, Alireza Salimi, Christian Moormann

"Rock mass classification systems are often applied in many empirical design practices in rock engineering, some contrasting with the original intent and applications of these classification systems, for example, estimation of TBM performance in various ground conditions. While accurate estimation of machine performance is significantly impacted by rock mass properties, parameters used in many of the existing classifications are more related to ground support design and not rock mass boreablity. The results of many investigations on this issue have shown a weak correlation between TBM rate of penetration and rock mass classification. This limitation can be overcome by fine tuning the rock mass classification input parameters to represent influence of rock mass properties on TBM performance as has been the objective of RME or QTBM. This paper will offer an overview of the impact of rock mass on TBM performance and introduces an empirical equation for predicting performance of rock TBMs based on rock mass classification. The results of the preliminary analysis of a new model has revealed that the use of the proposed system can offer a reasonable accuracy for estimation of TBM performance in various rock masses. 1. INTRODUCTION Hard rock tunnel boring has become more or less the standard method of tunneling for tunnels of various sizes with lengths over 1.5–2 km. Estimating the performance of TBM is a vital phase in tunnel design, and for the choice of the most appropriate excavation machine. During the past three decades, numerous TBM performance prediction models for evaluation of TBM rate of penetration and advance been proposed. In brief, all the TBM performance prediction models can be divided into two distinguished approaches, namely theoretical and empirical ones (Rostami et al., 1996). The most common and recent works on this topic are summarized in Table 1. Currently, two models including Colorado School of Mines or CSM (Rostami and Ozdemir, 1993; Rostami, 1997) and Norwegian University of Science and Technology or NTNU (Blindheim, 1979; Bruland, 1998) models are the most recognized TBM performance prediction and prognosis models in use around the world."

Jan 1, 2016

By William A. Vogely, Lawrence J. MacDonnell

This section begins with an introduction to several key environmental laws. This is followed by a discussion of some of the issues raised by such environmental regulation. Finally the subject of regulatory reform is addressed. Overview of Selected Major Environmental Laws The number, type and complexity of environmental laws and regulations affecting mineral resources development have grown at an astonishing rate since the 1960s. The most significant laws and regulations are those addressing the use of the public lands; those concerned with air quality, water quality, and surface reclamation; and those defining government responsibility for its actions having important environmental consequences. The laws and regulations governing activities on the public lands will be taken up in the section 5.15C, "Minerals and Land Management." In this section we will concentrate on five primary laws: the Clean Air Act, the Clean Water Act, the Surface Mining Control and Reclamation Act, the Endangered Species Act, and the National Environmental Policy Act. The Clean Air Act: The legislative and regulatory framework for controlling air pollution has developed in a series of steps. Most important for present purposes are the Clean Air Act of 1970 (P.L. 9 1-604) and the 1977 Amendments (P.L. 95-95). The rather complex air quality control scheme includes four key elements-national ambient air quality standards, state implementation plans, the prevention of significant deterioration program, and the non- attainment program. National Air Quality Standards. The 1970 Clean Air Act is a landmark law because it contains the first explicit recognition that pollution is a nationwide problem requiring a national control program. The federal government through the Environmental Protection Agency (EPA) was to establish national air quality standards for at least the six pollutants named in the Act (sulfur dioxide, carbon monoxide, total suspended particulates, photochemical oxidants, hydrocarbons, and nitrogen dioxide). These standards were to be established so as to protect public health, "allowing an adequate margin of safety." The cost of achieving these standards is not to be considered. The 1970 Act unrealistically required that these standards be achieved in all areas of the country by 1975. As the program has developed, the air quality control regions are now to be designated as "attainment" or "nonattainment" with respect to each of the national standards. State Implementation Plans. Under the Act the states are given the primary role in achieving the ambient standards. States are to develop and implement control plans governing emissions from all existing and new sources. These plans can include emission limitations for existing stationary sources, transportation control plans to reduce emissions from mobile sources, and pre- construction review of new stationary sources to assure compliance with new source performance standards. The EPA must approve all state implementation plans. Sanctions are given to the EPA to be applied if states fail to submit acceptable

Jan 1, 1985

By A. Haghighat, B. Lattimer

"Mine face ignition due to a high levels of methane is one of the most common fire incidents in underground coal mines. This work exams ignition scenarios in continuous miner headings. Depending on the magnitude of the ignition or resulting fire, the ventilation curtain in the continuous miner (CM) heading may be damaged or dislodged, affecting the ventilation into the area. A computational study was conducted to investigate the effects of different levels of damage to the ventilation curtain on the ventilation flow into the CM area. The computational fluid dynamics software Fire Dynamics Simulator (FDS), Version 6.0 was used to predict the conditions that develop due to a 200 kW fire in the coal mine face following a methane ignition with different levels of curtain damage. Smoke layer depth, temperatures and mass flow into the CM area were used to evaluate the impact of no damage to the curtain, partially dislodged curtain, and fully removed of the curtain. Partial removal of the curtain allowed more smoke to accumulate in the CM area and a reduction in ventilation into the CM area. With full removal of the curtain, the smoke accumulated through the entire depth of the CM area and flowed out the entrance to the CM area and the ventilation completely bypassed the region. INTRODUCTION Active working faces in underground coal mines are one the most hazardous locations in terms of fire events. According to Mine Safety and Health Administration (MSHA) data analysis, the highest number of non-fatal fire incidents was reported at mining faces, intersections and crosscut areas in comparison with other locations from 2000 to 2012. About 464 fires happened at active working faces from 2000 to 2012, most consisting of a methane ignition, in some cases followed by localized fire. These are high risk incidents due to the potential to raise float dust and damage ventilation systems, particularly auxiliary systems such as curtain or tubing. Depending on the magnitude of the ignition or fire, the ventilation curtain in the continuous miner (CM) area may be damaged or dislodged, affecting the ventilation into the area. Five computational fluid dynamics (CFD) scenarios were considered to investigate the smoke layer depth, temperature, visibility, mass flow rate, and the behavior of airflow in an entry with a continuous miner (CM) located in it. The state of the auxiliary ventilation was varied based on the assumption that as an ignition increases it magnitude it will affect ventilation curtain proportionally. Visibility and temperature along the height of the entry at different sections were investigated and the interface height at each section was determined. Also, the fresh air height was studied for tenability analysis in future. FDS, Version 6.0 was used to predict the conditions that develop due to a 200 kW fire on the coal mine face following a methane ignition with different levels of curtain damage. Smoke view software was used as the post processor to visualize and analyze methane fire behavior at the face. Most entry fires are reported as fuel-controlled fires as they are rarely restricted to air access (Ingason et al, 2014). The working face fire in the following models was assumed to be a fuel-controlled fire."

Jan 1, 2016