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By Sukumar Bandopadhyay

In recent years planning of surface mines in general and reclamation and post-mining land uses in particular have become very complex. Due to the lack of suitable techniques, land use plans are rarely based upon structured decisions. Data collection may be conducted in a rigorous manner and certain analyses may be performed on the data; the decision to put the land to a specific use, however, is finally based upon the intuitive judgment of one or several individuals. This paper demonstrates how techniques from fuzzy set theory can be used in order to select an optimum post-mining land use plan. The various land use planning alternatives have been characterized according to both qualitative information and quantitative factors and the "fuzzy" aspects of the collected information are incorporated into the analyses. In a practical application, the methodology is used to obtain the most reasonable solution to a post-mining land use planning problem in Interior Alaska.

Jan 1, 1986

By Oluwasegun Samuel Odebiyi, Shaona Wang, Feng Gao, Biao Liu, Hao Du

Recovering vanadium from vanadium titanium-magnetite (VTM) ore using ( NH4)2C2O4 is a clean hydrometallurgical process, but the drawback is the low recovery and slow kinetics due to the formation of inhibitor. A novel energy-efficient mathematical model was derived for green leaching of VTM in which the mechanical activation (MA) removed the inhibitor “δ” (formation of impermeable product layer of CaC2O4) covering the reacting core of the CaV2O6 leaching process in ( NH4)2C2O4 solution. Before the MA processing, the formation of the CaC2O4 layer affects the kinetics (slow) and NH4VO3 leachability (low recovery). The dissolution rate enhancement and economic importance (in terms of leaching kinetic/recovery) of mechanical activation (MA) pretreatment in hydrometallurgical processing cannot be overemphasized. It is shown from the experimental and developed mathematical model results that the rotating speed of the ball mill (ωb) has a significant effect on the NH4VO3 recovery. At 360 rpm, the experimental result gave an 82% optimum recovery rate and a reaction rate constant of 0.01889s−1 with close correlation with the present models at 82.8% and 81% for liquid-to-solid layer diffusion and chemical reaction controls, respectively, with a reaction rate constant of 0.018883s−1. The close correlation between the experimental recovery rate results and the diffusion recovery rate model result justifies that the leaching process is diffusion control shrinking core kinetic with experimentally measured activation energy (Ea) value of 19.502 kJ/mol . This present model proved that MA enhances the dissolution rate regardless of the formation of a passivation layer on the material and best describes the kinetics of the MA hydrometallurgical processes compared to the shrinking core model.

Nov 3, 2023

By W. M. Aubrey

Cobbing, as used in this; paper, refers to coarse dry magnetics separation. It is applicable when, by its practice, plant cost can be reduced or the value of its products increased by the removal of a barren or lean reject or a high grade final product. This paper attempts to describe cobbing as it is now being practiced, and also the problems that are of concern to the operator and design engineer. In preparation, 16 plants were contacted, all of which were very cooperative with their time and data.

Jan 1, 1958

By John Conway, Gerald Bennett, John Herrick

Research efforts which have led to reduced resin bolting costs at White Pine Mine are described. Key factor was development of the capability to drill small holes (1 1/8 in. diam) in the hard (20,000-30,000 psi) White Pine roof rock. Economic data comparing the 1 1/8 in fully-grouted Resin Bolt to the conventional 1 3/8 in fully-grouted bolt is also included. The development of a method which allows the Resin Bolt to hold itself in the hole thus removing the requirement for the operator to break his "work momentum" while he stops and waits for the resin to set is also described. This technique increased bolter productivity by 23% in a recent full-scale unit test.

Jan 1, 1974

By Michael N. Maltezos

"There is certainly no argument that LED lighting systems have taken a strong foothold in the lighting marketplace over the last several years. This has even proven true in the world of transportation and transit lighting, for which new LED cobra head style luminaires are replacing traditional HID cobra head luminaires on North America’s roadwaysand linear LED light fixtures are replacing conventional linear fluorescent light fixtures in North American rail transit facilities. However, LED technology has taken a while longer to penetrate the very specific market of vehicular tunnel lighting in this continent. Though both the New York/New Jersey Holland and Lincoln Tunnels have recently been retrofitted with LED lighting, and an LED Lighting RFP is currently out for Boston’s Central Artery Tunnels, very few vehicular tunnels in North America to date have been illuminated with LED light fixtures. This is largely because cost effective LED lighting, that met our typically stringent tunnel lighting standards, was until recently simply unattainable. However, with the rapid advances in LED technology over recent years, owners and specifiers of North American tunnel lighting projects have finally begun to adopt LED lighting systems as the norm. In fact, a recent Lux Fit/Yole Development “LED in Road and Street Lighting Report” stated that “LED luminaire growth will be driven firstly by tunnel lighting, and then relayed into highway, road, residential and amenity lighting applications starting in 2014.” 1 Our highways are continually becoming more congested. As a result, Provincial and State Departments of Transportation (DOTs) are constantly looking for innovative ways to improve traffic flow. One way DOTs are now helping to ease congestion is by expanding the use of tunnels and long underpasses in large interchange reconstruction projects. With less available right-of-way to work with, and the high costs of maintaining elevated bridge structures over the years, it often makes more sense to “go under” (rather than over) the traffic congestion points. With the addition of these new tunnels and long underpasses comes the issue of proper illumination within these structures, for a safe and efficient driving task. DOTs use recommended lighting practices and guidelines for highway lighting, which include specific criteria for tunnels, set by either the Illuminating Engineering Society of North America (IESNA) or the American Association of State Highway and Transportation Officials (AASHTO). However, both IESNA and AASHTO point out that these recommended practices and guidelines are not a mandate, and DOTs are free to make their own decisions about lighting criteria. Accordingly, effectively illuminating tunnels is often times a challenge. This paper will examine the key considerations of the tunnel lighting application in generalas well as what LEDs now bring to the table and how, accordingly, traditional lighting technologies will be phased out in the future illumination of tunnels."

Jan 1, 2016

By K. Rushdi, B. E. Abulnaga

The conventional Froude number is blind to the presence of solids, their density and their concentration in a stream of slurry mixture such as tailings flowing in an open channel. This often leads to rough approximations of subcritical, critical and supercritical regimes, based on one phase flow Froude number, limiting subcritical to a value smaller than 0.8 and supercritical to values above 1.4, as proposed in the past by Green, Abulnaga and other authors. While acceptable for small flows, such approximations can be uneconomical for the larger flows encountered in some modern plants that treat up to half a million t/day. A review of concepts of a densimetric Froude number sheds some light on the effect of solids on stratification prior and subsequent to a hydraulic jump. While the approach is heavily borrowed from modern sedimentology, it provides a useful tool to designers of large launders or open channel tailings systems. These concepts are reviewed with some practical examples.

Jan 1, 2013

By J. S. McAlpine, J. Matousek, W. Muir, P. Downey, K. Major

The Golden Bear refractory gold ore roasting operation is located at Huddy Lake, in northwestern British Columbia, about BO km northwest of Telegraph Creek (see Figure 1). The mine access road, used for supplies delivery, was developed by Golden Bear and consists of a radio controlled 155 km gravel road originating at Highway 114. Hine operations are based on a two week in, two week out rotating shift schedule with personnel transport by chartered aircraft from Vancouver, Whitehorse or the 3 Talthan conmunities. The site runway Is located adjacent to the tailings impoundment.

Jan 1, 1992

By John W. Nebgen

Surface water quality is determined by complicated interactions between water and land. Runoff--the flow of waters in surface streams and rivers-¬represents the total amount of water collected in a drainage basin or watershed that appears at the outlet of the basin. As the water flows through the basin, it is in contact with land and can pick up impurities from the land. Thus, surface waters are not pure--they contain impurities, or "pollutants," in vary¬ing concentrations determined by the nature of the land which they drain. The composition of surface waters thus tends to represent a steady state equilibrium between interactions of water and land. However, when man utilizes the land in the drainage basin or watershed, the natural equilibrium between water in the runoff and the land is disturbed. Such disturbances usually effect adverse changes in surface water quality, as new equilibrium conditions between land and water are established. These adverse changes in surface water quality can be thought of as "nonpoint pollution." Esti¬mation of nonpoint pollutant loads thus ultimately reduces to determining the magnitude of the differences between water qualities before and after man's disturbance of land within a watershed. The important key in making such an estimation lies in the determination of water quality in the natural or "back¬ground" condition of the watershed. In subsequent discussion in this paper, tools for making an estimation of background water quality will be described.

Jan 1, 1975

By Andrew N. Peterson

US mine operators frequently fail to investigate more cost effective and productive bulk material handling systems because surface mines seem to lend themselves to truck ore haulage. In this country, as a result, use of conveyors to move heavy loads from mine to process facilities has been minimized, if not actually neglected. In contrast, there are more than 50 conveyorized surface mines in successful operation around the world. These mine operators have learned that properly applied conveyorized systems can offer major savings in capital and operating costs, which contribute to improved profits when combined with other proven mining technologies. Growing acceptance and application of conveyorized bulk material handling in surface mines also points up how unique each mine is and how careful planning contributes to maximum mine effectiveness. Because of these differences, mining executives and technical and operating staffs need to develop an understanding of three factors in applying conveyorized bulk material handling in surface mines: • Why each mine will benefit from the type of automation permitted by conveyorized operation, •What kind of equipment is available, and • What applications most effectively demonstrate the first two factors in action - hauling either ore or waste. The conveyorized systems considered in this presentation have production rates from 0.5-2.7 kt/h (500-3,000 stph). Worldwide, these systems have been operating since the early 1960s. Advantages of Conveyors Why do you want conveyorized bulk material handling? First, it almost always provides lower operating and maintenance costs. Second, it frequently requires lower initial capital costs and almost always requires lower capital costs over the life of the surface mine. Third, it provides comparable operating availability, and finally, it frequently gives comparable operating flexibility - depending on the mine plan. Cost avoidance can be accomplished with modern production methods. These, in turn, permit increased productivity and reduced operating costs such as those for energy, maintenance, and manpower. It has been demonstrated in European surface mines and elsewhere, that conveyor systems frequently require lower initial costs than does truck haulage. Almost always such operations require lower capital costs over the mine life. Those costs include the continual addition of haulage trucks to both accommodate the increasingly difficult haulage routes and fulfill replacement requirements when trucks wear out. Conveyor systems handling ore in numerous large crushing and port facilities, which have operated since the early 1950s, have clearly demonstrated a useful conveyor life of more than 25 years. In contrast, off-highway trucks have life spans of six to eight years. The following examples illustrate comparative capital costs to purchase conveyor systems and comparable truck haulage units. Example 1 The ore haulage route from point A to point B is level and 610m (2,000 ft) long. The material weighs 1.8 t/m3 (110 lbs per cu ft) and must be transported at a rate of 1.8 kt/h (2,000 stph). The installed capital costs to provide a properly designed conveyor that will transport the described material from point A to B is about $450,000. The capital cost to purchase three 77-t (85-st) off-highway trucks and one spare truck - which would provide equivalent capacity - would be about $1.2 million. The truck cost estimate is based on a 6 min. or 771 kt/h (850 stph) truck cycle time. Truck efficiency is estimated at 0.8. Each 77-t (85-st) truck would have an actual haulage rate of 617 kt/h (680 stph). Therefore, three trucks would be necessary to transport the designated tonnage of 1.8 kt/h (2,000 stph). A movable crushing plant would be located at point A for the conveyors and a permanent crushing plant at point B for the truck haulage system. Capital costs for these primary crushing plants were not included in the calculations for either system because the capital costs are frequently comparable. Example 2 The transport route from point A to point B is 610 m (2,000 ft) horizontally and 122 m (400 ft) vertically - on a 20% grade (Fig. 1). The material weighs 1.8 t/m3 (110 lbs per cu ft) and must be moved at a rate of 1.8 kt/h (2,000 stph).

Jan 6, 1983

By Frank Hagar, George M. L. Robinson

INTRODUCTION Mine waste monitoring and management is essential when the industry is being required to accept the environmental liability for all generated, stored and disposed solid and hazardous waste. Environmental regulations mandate the operator to minimize waste production while requiring the operator to cleanup existing contamination. Since these requirements are being enforced, many operators do not have a clear under- standing, whether their existing operation will or could be required to adopt remedial plans to mitigate off-site contamination impacts. The following methods, using conventional and advanced geostatistical methods, provide a tool to make appropriate assessments whether existing or potential contaminant issues are present. BACKGROUND Generated solid wastes from mining operations are currently exempt from Solid Waste Disposal Act (SWDA) Sub- title C (RCRA), statutes and promulgated regulations, however, compliance with SWDA Subtitle D statutes and regulations is required. In order for the mining operator to be exempt from hazardous waste regulations, the operator must demonstrate that generated waste does not have hazardous waste characteristics. In many instances the operator will be able to use statistical tools and their existing data to determine whether their site could be a potential hazardous waste liability. METHODS The following statistical and geostatistical methods can be used to determine whether existing wastes could be a regulatory concern. The following presents a brief discussion of standard statistical methods and discusses, in greater detail, how advanced geostatistical tools can be used to define potential waste issues. The following will discuss how data can be screened, "Data Filtering and Reporting"; how data can be evaluated using "Conventional Statistics"; followed by a detailed discussion o f "Geostatistical and Estimation Techniques" and "Statistical Modeling". Data Filtering and Reporting Data filtering is the simplest, but potentially the most powerful statistical tool because data can be easily sorted to meet regulatory reporting requirements. Filtering includes unions and intersections of data such as date, maximum and minimum values of one or several variables. Using the data base presented in "Mine Waste Data Base Management Procedures", Robinson and Hagar, 1987, an example of a filter group is presented.

Jan 1, 1987

By H. Wagner

INTRODUCTION One of the most important tasks facing the opera¬tors of deep-level gold mines is supporting the roof strata in the immediate vicinity of the stope faces. Some of the deeper gold mines operate at depths ex¬ceeding 3.0 km; the extreme mining depths and the tabular nature of the gold-bearing reefs result in high stress concentrations at the abutments of the stope faces. These, in turn, lead to extensive fracturing of even the hardest quartzites. Although most of these fractures develop in a stable manner, there have been many instances where rock failure occurred suddenly, resulting in a considerable amount of damage to the underground workings. Such violent rock failures commonly are known as "rock bursts," and they are typical of many hard-rock mines that are operating at great depths. To safeguard mining personnel and equipment against the effects of stable and unstable rock failures, adequate support must be provided to the fractured roof as quickly and as effec¬tively as possible. Traditionally, timber props and timber packs have been utilized to provide roof support in gold mine stopes up to 1.5 m wide. Both methods of support suffer from the fundamental disadvantage of generating sup¬port only in reaction to movement of the strata. Since unrestrained strata movement often results in a break¬down of the frictional forces that preserve the stability of the intensely fractured roof strata, it is essential that stope supports have rapid load-bearing characteristics. An equally important requirement is that the roof sup¬ports be able to accommodate displacements of the rock mass. A third requirement of roof supports in gold mine stopes is that they must be able to accommodate the high rates of stope convergence typical of rock bursts. The hydraulic prop is the obvious choice for sup¬porting the stope faces in deep-level hard-rock mines. Since hydraulic props can be installed with a positive setting load, they can provide roof support that is independent of strata movement. By equipping the hydraulic props with yield valves, they meet the require¬ment of being able to accommodate rock-mass displace¬ments. However, the requirement of being able to accommodate high rates of stope convergence without overloading or damaging the rock strata was rather difficult to meet. The first introduction of hydraulic roof supports into gold mine stopes showed that conventional hy¬draulic props, such as those used in coal mines, were completely unsuitable for a number of reasons, in¬cluding: 1) Since drilling and blasting are used to break the ore in gold mine stopes, supports installed close enough to be effective are exposed to the vigor of the blast. Conventional coal-mining props suffered extensive blast damage, despite being protected by a blast barricade. 2) The environmental conditions in gold mine stopes favor corrosion. The high quartz content and the abrasiveness of the ore further aggravate the problem by damaging the protective coatings on the hydraulic surfaces. Simply changing the design of gold mine props to have the piston project from the bottom rather than from the top resulted in dramatic improvements in the service life of the props. The improvement was attributable to external water in the stope washing the fine quartz grit away from the hydraulic surfaces, rather than concentrating the particles between the cylinder and piston of the prop. 3) The most obvious deficiency of conventional coal mining props was their inability to yield rapidly enough to accommodate the high convergence rates of rock bursts without overloading the supports. As a result of the first disappointing results with hydraulic supports in narrow hard-rock stopes mined by drilling and blasting, a comprehensive research and development program was undertaken. The hydraulic props resulting from several years of research and exten¬sive field trials are described herein. To date (1978), more than 130,000 of these props have been manufac¬tured and used successfully in a number of mines and under a variety of geological conditions. Although many of the detailed specifications are directed spe¬cifically to gold mining conditions, there are a number of points that are of general importance in the design of underground support systems for tabular excavations in hard-rock mines of any type. SPECIFICATIONS FOR RAPID-YIELDING PROPS Yield Requirements The yield requirements for hydraulic props in deep¬level hard-rock gold mines are summarized in the fol¬lowing paragraphs. Slow Yield Load: The design of the yield valve must allow the yield load to be preset to between 300 and 400 kN. This flexibility is necessary to account for the differences in the strength properties of the roof and floor strata. Drop in Load Under Slow Yield: The drop in sup¬port load during a slow yield should be as small as possible, but it should not exceed 5% of the slow-yield load. Rapid-Yield Load: The load exerted by the prop during periods of rapid stope convergence should be as close as possible to the slow-yield load. The rapid-yield load should not exceed the slow-yield load by more than 15% at yield rates of 1.0 m/s. The limitation of the upper valve of the yield load is important; it deter¬mines the hydraulic performance of the yield valve. The hydraulic props that satisfy this criterion have performed well, even under severe rock bursts. Load Changes Under Rapid Load: On some of the earlier rapid-yielding props, conditions of dynamic in¬stability were observed; these conditions resulted in a complete breakdown of support resistance. It is essen¬tial that the force oscillations during rapid yielding be as small as possible, not exceeding -*5% of the average rapid-yield load at a yield rate of 1.0 m/s. Longitudinal Resilience: During rock bursts, vibra¬tions of the roof and floor sometimes are observed. To

Jan 1, 1982

By Ramarao Inguva

Feasibility studies being conducted to investigate the use of electromagnetic methods for insitu volumetric heating of oil shales will be discussed. A two dimensional numerical model which describes eletromagnetic heating of oil shales is outlines. The model includes equations for temperature, pressure, saturations, chemical reactions, mass conservation, and source terms. The gases are all assumed to form one bulk species and the oil is assumed to remain in liquid form. The chemical reactions include pryolysis of kerogen and char, release of bound water, coking, and decomposition if carbonates. Porosity and permeability are dynamic functions of the organic materials. Calibration of the model is accomplished by comparison of the model results with experimental data obtained by IITRI. Nonlinear relationships for viscosity, thermal properties, and source terms and used as inputs to the model. A finite difference approximation to the differential equations is derived and solved using Newton's iteration technique. For the cases studied the solutions are quite stable. Numerical resultes are included and a preliminary study of the optimization of the heating process is presented.

Jan 1, 1984

By Eugene P. Pfleider

The mining industry of the World, and particularly of the United States, has made a complete reversal from underground to surface mining methods since the turn of the 20th Century. This has occurred even as average ore grades were decreasing and strip ratios rising. In the early 1900's there were over 100 underground mines producing from the three iron ranges of Minnesota -- today there are hone. Practically all of our coal prior to 1930 was mined underground; today over one-third is from surface operations and that percentage is increasing. Although world mining has hot changed to surface techniques as rapidly as has the U. S. Industry, the shift is escalating and will approach our figures shortly. A comparison of World and U. S. production figures are shown in Table 1, taken from the AIME Surface Mining volume, and the trend rates for the U. S. are depicted in Fig. 1.

Jan 1, 1968

By B. M. Sadashiva Murthy

Increasing quantities of nutrients and pesticides in agricultural runoff in recent years has caused the more developed western nations to become concerned about diffuse agricultural pollution. Thus, the problem of diffuse pollution is of greater importance and concern for any integrated water quality management programme. The above mentioned sources and activities causing pollution to groundwater cannot be completely avoided. The best solution is to entail a firm understanding of the principles of solute transport through porous media. The complex factors that control the movement of contaminants in porous media and the resulting behavior of contaminant plume are usually intricate to assess because of interaction of many factors such as dispersion, advection, sorption, degradation, volatilization, etc. As accurate quantification of solute under field conditions is inherently difficult, the fate of nitrate and phosphate have been analyzed in laboratory column and channel studies. From the analysis of the breakthrough curves, the dispersion co-efficient for nitrates and phosphates through sandy soil was found to be 0.262 m2/d and 0.114 m2/d for column studies, 0.321 m2/d and 0.231 m2/d for channel studies respectively. The column studies revealed that the concentration of nitrates and phosphates increased steadily in the first few days (around 5 days) and then it increased rapidly after 8 to 10 days. However, it attained equilibrium after 20 days. Similarly, the channel studies revealed a steady increase in concentration of nitrates and phosphates in the first few days (1 to 2 days) and rapid increase up to 15 days and there after it attained equilibrium. In the study, one-dimensional analytical model has been developed which include the advection, dispersion, and a characteristic term called ?total elimination rate?. The comparative study of column and channel studies, and model output (in which the term total elimination rate ?K? is considered as zero) exhibited a variation of 30 to 50 % in leaching characteristics of pollutants (nitrates and phosphates).

Jan 1, 2008

By Francis W. Brown, Philip R. Hunt, Douglas N. Halbe

Refractory arsenopyrite ore from Western Mining Corporation's Lancefield deposit in Western Australia is treated by fluosolids roasting of a flotation concentrate followed by cyanidation of calcine and flotation tailings. The project development is reviewed from original testwork through circuit design, operating experience, and subsequent expansion.

Jan 1, 1990

By H. Nematollahi

The comminution laws The grindability of the ores or minerals is an important factor that could not be deduced from their mineralogical characteristics (Testut, 1958). Many theories have been proposed to determine the amount of work required in a comminution operation as a function of the nature of material, size and shape of the minerals before and after of comminution. The most important laws are proposed by Rittinger, Kick and Bond. According to Rittinger (1867), the work is directly proportional to the new surfaces produced during the comminution. Kick (1885) believes that the work needed to produce similar modification is proportional to the volume or mass of the material. Bond, during his 25 years of experience and research, reached to the conclusion that on the average the energy required for a known comminution is between the Rittinger's and Kick's laws (Bond, 1952). According to Bond's Third Theory, the work input is proportional to the new crack tip length produced during the particle breakage, and equals the work represented by the product minus that represented by the feed.

Jan 1, 1994

By Joel K. Waterland

GENERAL DESCRIPTION Homestake Mining Co.'s operations are at Lead, SD. Production from the various methods used are: 1 155 753 t/a (1,274,000 stpy) by open cut-and-fill, 68 039 t/a (75,000 stpy) by square set cut-and-fill, 144242 t/a (159,000 stpy) by shrinkage stoping, 107 048 t/ a (118,000 stpy) by blasthole stoping, and 67 132 t/a (74,000 stpy) in development work for a total of 1 542 214 t/a (1,700,000 stpy). Mining takes place from the 616-m (2000-ft) level to the 2073-m (6800 ft) level (Fig. 1). The average travel time to the stope is 45 min. GENERAL ORE BODY REQUIREMENTS AND LIMITATIONS Size, Shape, and Dip of Ore Body Six major ledges varying from 914 m (3000 ft) long by 228.6 m (750 ft) wide to 305 m (1000 ft) long by 122 m (400 ft) wide are mined. Within these ledges are irregular-shaped areas of varying sizes. These ledges dip at approximately 1.2 rad (70°) to the east and plunge to the south from 0.26 to 1.57 rad (15° to 90°). Ground Conditions The ore is cummingtonite (chlorite schist) which is very competent except for major bedding planes and fracture patterns. The footwall is a slate but because of the dip presents very few problems. The hanging wall is also a slate which because of the dip and bedding is very weak and requires considerable rockbolting. No problem has been encountered with rock bursts to a depth of 2438 m (8000 ft). Ore Value The ore values vary somewhat from ledge to ledge, but the average ore delivered to the mill is approxi¬mately 6.2 g (0.2 oz) of gold per ton. A small amount of silver is the only byproduct of this operation. Annual production of gold is approximately 10 575 183 g (340,000 troy oz). Production Requirements The mine has a mill capacity of approximately 1 723 651 t (1,900,000 st) but because of several fac¬tors (manpower, depth, etc.) this mill capacity has not been attainable for the past several years.

Jan 1, 1982

By LeEtta M. Shaffner, John R. Marks

The Homestake Gold Mine in Lead, South Dakota, commenced operations in 1876. As is the case with old, deep, continuously developing mines, a ventilation improvement is periodically required to maintain acceptable underground environmental conditions. Recent historical improvements at Homestake include a 5.2m diameter air shaft driven in the 1960's and a 2.1 MWR (580 ton) chilled water plant installed in 1978. By 1983, it became apparent that yet another ventilation upgrade would be needed to keep pace with accelerated development in the deepest mining sections. A study was therefore undertaken to project ventilation requirements for the next ten years and to select the method(s) most suitable to meet those requirements. The study called for a two-phase approach in which air flow and air conditioning were carefully balanced. Phase I, the installation of a new 2240 kW surface fan and several underground circuit changes, was completed in 1986. This paper describes Phase 11: the planning, design, installation and initial performance of the air-conditioning portion of the upgrade.

Jan 1, 1989

By R. L. Wiegel, G. R. Oswald

The processors of Florida phosphate rock face constraints similar to those of other mineral operations--leaner ore, more complex treatment schemes and a product which sells for a penny a pound. IMC Fertilizer is a dominant producer in this market with its current operation of five processing plants. An emphasis by their management in maintaining and improving plant performance has continued unabated for some 15 years. This has resulted in a commitment to the importance of routine automatic sampling of product and in process streams, the generation of reliable assay and size distribution data, the accurate measurement of process flows, and the computerized "rendering" of this information into weekly and monthly material balances which provide consistent measures of process performance. In addition, there has been a parallel program to monitor and improve the performance of flotation reagents and to evaluate process modifications or changes in equipment. This paper will describe the evaluation techniques that have evolved over this period and indicate how the historical data base is used to identify plant problems early and help in their solution.

Jan 1, 1991

By J. P. Nairn, C. M. McCulloch

More and more underground mining is being conducted using the long wall method. Likewise, many new surface mines use area or mountaintop removal methods. These methods can have a significant impact on surface and ground water resources. The overall study of the effects on surface and ground water from mining is referred to as the probable hydrologic consequences (PHC) determination of mining and reclamation. Collection and interpretation of information concerning ground water and surface water quality and quantity, as well as detailed geologic analysis, is required to adequately define the impacts of mining. This paper discusses the present day requirements and methodology of preparing a PHC for a large mining operation in the eastern coalfields.

Jan 1, 1997