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By Eugene M. Trisko

Presentation Overview State-Of-The-Art Scrub/Switch Analyses > Allegheny Power System > PSI Energy UMWA Phase I Coal Interests > 16 Phase I Scrub Plant Coal Profiles > Coal Price/Emission Allowance Interaction Southern Company Case Study > 2+ Million Ton Phase II Allowance Purchases > 10+ Million Ton Phase I Coal Switch > Georgia PSC Proposed Fuel Price Cap > Shift/Avoid Georgia Scub Costs Through System Allowance Purchases

Jan 1, 1993

By Gerald H. Luttrell

The determination of mass balances is the first step in analyzing the performance of processing circuits. Although conceptually very simple, the mathematics associated with mass balances can be cumbersome when conflicting data sets and/or complex circuits are evaluated. Fortunately, many of the spreadsheet programs available today include powerful search routines which can be adapted to solve common mass balance problems. To demonstrate these capabilities, a generalized mass balance program has been developed using the Microsoft Excel? spreadsheet. Compared to commercial programs, the spreadsheet format is user-friendly, more versatile and easier to customize. This paper reviews the mass balance problem and describes how spreadsheet tools can be used to reconcile conflicting data.

Jan 1, 1996

By R. Bhaskar

The advantages of recirculation of air in underground mines have been well recognized, and several papers have been written on the subject. Issues of concern to the various segments of the mining industry relate to the health and safety of workers, specifically, methane and respirable dust build-up in the air, high humidity and temperature at the work face. This paper presents a survey of various studies pertaining to recirculation as a prelude to the experimental and quantitative studies performed by the authors. Experiments were performed at a trona mine on the transportation and deposition of dust along the return airways, for three different velocities. Modeling studies were performed using dust deposition models. The model predicted data were compared with experimental data in order to lay the foundation for the development of advanced predictor models for recirculation in trona mines. Two models for dust deposition were analyzed. The model predicted data are in divergence from the experimental data, indicating the need to develop better models.

Jan 1, 1992

By G. T. Swanby

Members of AIME, I read to you now a portion of a very fine business letter which we received several years ago. This letter originated in Rangoon, Burma, and reads in part: "Rest assured, if your goodselves see with us eye to eye, sure as certain we should get the business". I don't plan to give anybody "the business" today, but you can rest assured that if some of "you goodselves see with me eye to eye" on what I am about to discuss, I would be most pleased. My talk with you today will discuss the Federal Corporate income tax and its effect on our lives as engineers. In the-engineering-construction business we are faced with all the usual form of taxation which includes such items as sales tax, use tax, school tax, contractor; gross receipt tax, import duties and excise taxes, severance taxes, etc, adinfinutum.

Jan 1, 1965

By D. F. Doerr, E. Blalock, D. R. Bush, K. D. Cohen

"INTRODUCTION The design, development, fabrication, and test of cryogenic breathing apparatus is part of a much larger effort funded by the National Institute for Occupational Safety and Health (NIOSH) and managed through a Space Act Agreement with the National Aeronautics and Space Administration (NASA) at the Kennedy Space Center (KSC) in Florida. This effort is designed to create cryogenically based life support equipment that is responsive to the needs of miners as required by the Miner Act of 2006. Our goal was to design and build a liquid air based self-contained breathing apparatus (SCBA) that lasted 2 hours and would be used for the egress of miners during a mining accident and be refillable while worn. Therefore, the current report describes tests of an Advanced Cryogenic Breathing Apparatus (termed the ACryoBA) designed to provide miners egressing an emergency situation with a two-hour open-circuit SCBA. The ACryoBA utilizes low pressure cryogenic liquid air instead of high pressure compressed air commonly used in most commercially available SCBA. The ACryoBA can also be self-filled from strategically placed Cryogenic Air Supply and Fill Stations (CryoASFS) initially, and thereafter on the egress route approximately every 1 hour and 30 minutes with a 30 minute air reserve. The ACryoBA evolved originally from a one hour Liquid Air Pack (LAP) developed in the 1980’s for Space Shuttle Rescue forces allowing for longer duration and cool air (Figure 1). It was used successfully for many years, through the end of the Space Shuttle Program. The first attempt at a mine egress pack was the Cryogenic Breathing Apparatus (Figure 2). It was to have a low profile, two hours of breathing, attitude independence, and a simple rapid refill while in use. The CryoBA met the two hour criteria, but with difficulty due to excessive heat leakage caused by the dual 4 liter Dewar design. Much of the stored air was lost as it vaporized faster than it could be used. However, the pack was successful in demonstrating both attitude independence and a simple rapid refill capability. The ACryoBA project was designed to continue the progression and address the deficiencies in the CryoBA. The ACryoBA pack was designed to last 2 hours. It minimizes the heat leakage with a single Dewar and thereby requires less liquid air. The single Dewar design also minimizes weight, making it much more manageable by the user (Figure 3). The ACryoBA complies with 42 CFR part 84 NIOSH certification test requirements. One critical requirement for the ACryoBA is operation in positions other than vertical for periods up to 1/4 (i.e. 30 minutes) of the rated service life of 2 hours; this was accomplished by use of new technology called the “attitude independent pickup” which is abbreviated “AIP.” The AIP, developed by BCS Life Support LLC (patent #8,899,226), has a tube going from the top flange down through the center of the Dewar. At the end it has a flexible bellows and a weighted end. Due to the flexible nature of the bellows, the pickup at the end is free to rotate and follow the liquid level around within +/- 90o of vertical."

Jan 1, 2016

By R. H. Weiland

The dewatering of flocculated clay suspensions by compression in a centrifugal field has been investigated. The results are evaluated with regard to both direct applicability to centrifugal dewatering, in solid-bowl centrifuges for example, and indirect applications to gravity sedimentation systems. It is well known that sediment consolidation under gravity depends on structural characteristics such as permeability and on the "self-weight" of overlying sediment layers. An important objective of the study has been to evaluate the self-weight effect using centrifugal forces to simulate consolidation in deep sediments. In this way, small-scale laboratory tests can be used to predict the rates and limits of sediment compression in industrial systems such as thickeners and settling ponds. Experiments have been conducted in which the sediment mass and initial structure were maintained constant while the effective sediment weight was varied by centrifuging at different speeds. The effects of initial structure have also been studied using controlled variations in flocculation conditions.

Jan 1, 1993

By R. W. M. Lai

The study of flotation kinetics was first reported by Garcia-Zuniga1 in 1935. Since then, literature on the subject has grown with the time. 2-19 Although there is an abundance of flotation kinet¬ics models available in the literature to describe flo¬tation systems, they are mostly of academic interest and are seldom applicable for use in the industrial environment. Several reasons contribute to the wide gap in the industrial -application of the academic models. These include: 1) the lack of generality in the model, e.g., the model is limited to certain size ranges; 14 2) the academic models involve complicated mathematics; 5,6,10,11 3) confusion about the order of the flo¬tation rate, e.g., several authors proposed a first order rate model, 1,15,16 whereas the others propagated a second order rate model: 2,17,18,194) the use of an unrealistic rigid value, such as the use of a maximum recovery of 100%, 5,8,19 which is unrealistic in industrial operations; and 5) the use of graphs that confuse the reader rather than interpret information. 2,3,10 This paper intends to introduce a simple and easy to understand empirical flotation kinetics model along with a way of presenting the model in an informative graphical form, which should stimulate the interest of other practical engineers to become concerned with practical application within the mineral industry.

Jan 1, 1982

By W. G. Kegel

Coal mining today is confronted with numerous problems, all of which affect in some way the ability of the operator to produce profitably. The major endeavor, therefore, is a quest for cost lowering techniques. Complete belt haulage from shuttle car to river barge appeared to be a step in such a direction. A deep look into all aspects proved this to be more involved than just the installation of such a belt line. With this paper, we will attempt to present to you the problems and requirements of design and installation of an all-belt haulage system, believed to be the longest underground belt installation in the world at this time. The first and most important item is the justification of an all-belt haulage system. The following is a brief history of the coal property and the facts affecting our decision.

Jan 1, 1964

By F. Calizaya

This study summarizes the ventilation requirements for a highly mechanized P.T.Freeport Indonesia's underground mine operation in Irian Jaya, Indonesia. The Deep Ore Zone (DOZ) is a copper-gold deposit being developed underneath the current Intermediate Ore Zone (IOZ) mine. One of company's current plans is to prepare this mine for a steady oreflow of 25,000 tpd by year 2003. This study includes the estimation of airflow requirements for various mining activities, the design of major intakes and returns, the determination of airway resistances and specifications of fan duties. It also includes the results of air pressure/quantity measurements in existing airways and the standards stated by the current Indonesian mining law.

Jan 1, 1998

By Karel Rössler, Petr Vítek

"The Ejpovice tunnels in Czech Republic were built by EPBM in soft Clyashale, and in weathered profile with low soil overburden. The segmented liner at the cross-passage openings required support, which would not interfere with the EPBM clearance envelope during the scheduled pull back of the EPBM through both tunnel tubes. For that reason support frames or radial bolting could not be used. Steel rods inserted into the neighboring segments during the ring assembly, and later grouted were tested and realized as an innovative solution. The paper presents practical experience gained with the segmented liner support during cross-passages construction. INTRODUCTION An innovative solution using the grouted dowels was developed and realized for sixteen cross-passage openings of the twin Ejpovice Tunnels, whose construction was part of the railway track Rokycany – Plzen modernization. The following paper described practical experience gained with the innovative support of cross-passage openings, which was realized by short steel dowels grouted within the segments of the EPBM segmented liner. The paper is a continuation of the paper published in WTC 2015, which described the design aspects of the grouted dowels support, while the following paper concentrated on the production, and the performance of the dowel support observed during the breakout for the cross-passages openings. The connection by grouted dowels was patented by Metrostav, a.s. Company THE EJPOVICE TUNNELS CONSTRUCTION The Ejpovice tunnels construction started in 2013. The start of the high speed train operation through the tunnels was planned for 2018. The project was funded by the state government with the support of European Union funds of up to 70%.The tunnels were excavated with one EPBM (Earth Pressure Balanced Machine) with the external diameter of 9.89 m. The segmental liner inner diameter was 8.7 m, and thickness of 0.4 m. First, the South tunnel tube was excavated from the East portal, then the EPBM was pulled back through the South tunnel, and the excavation was started from the same portal for the North tube. After the South tube was freed from the EPBM excavation operations the cross-passage construction started. Due to the short time schedule, in the North tube the cross-passage construction started while the tunnel was still under construction. Therefore, the cross-passage construction was performed concurrently with the segments transportation, and with the EPBM pull-back through the tunnel. There were 8 cross-passages along the tunnels with a maximum distance of about 500 m, Fig.1."

Jan 1, 2016

By R. M. Imhof, M. J. G. Battersby, J. V. Brown

There is a plethora of former industrial sites where coal mining operations have left large slurry impoundments. These contain raw washed fines, which have previously been too expensive to process to requisite grades for commercial use. New technology has been developed for fine material processing, namely the Imhoflot pneumatic flotation G-Cell. This froth flotation technique is a highly efficient means of concentrating coal and is particularly appropriate to the nature of materials encountered in tailings ponds. The high volumetric throughput resulting from the vastly reduced residence time in the cell allows for drastically reduced equipment sizes when compared to conventional flotation cells. This means the process, when combined with innovative pre treatment and filtration equipment can be developed as a mobile plant concept. This is seen as a minimum requirement when re-treating and rehabilitating fine coal ponds.

Jan 1, 2003

By H. T. Kang

Various geological anomalies are encountered in underground longwall mines, and they cause stability problems. In this study, a number of detailed two-dimensional finite-element models were made, consisting of mine floor, roof, coal seam, shield structure, gob, etc. to analyze the influence of geological anomalies on longwall shields. Two different categories of anomalies were simulated. The first ones are shear zone and sandstone channels, with variable sizes and locations in the roof. The second category is fault or fracture plane, with variable friction factors, locations, and orientation of the fracture plane. The results of the analyses are' integrated with an artificial intelligence system for developing a forecasting guideline for prevention of underground hazards due to the existence of geological anomalies.

Jan 1, 1996

By Michael H. Vallez

On September 13, 1973 MAPCO Inc. leased from Pocahontas Land Corporation an 18,000 acre tract of coal lands in Eastern Kentucky's Martin County (See Figure 1.). In July, 1974 initial run of mine coal shipments commenced and in April, 1976 shipments of a 12,500 BTU, less than 1% sulphur, washed coal was being shipped. Results of exploration demonstrated that large quantities of overburden would have to be moved. MAPCO decided to invest in large surface mining equipment to tackle the job.

Jan 1, 1981

By R. Cook

Knowledge based applications are becoming important to Associated Manganese for efficiently dispatching ore of appropriate grades to customers on time. The G2 expert system shell has been used to develop blending and scheduling applications using a combination of object-oriented rule based, procedural, and heuristic approaches. The blending application, for example uses a heuristic approach for creating blends from thousands of small stacks of manganese ore of various grades and sizes, to meet customer specifications while fully exploiting the available inventory. Data capture and data warehousing have become important issues, and the Internet shows strong potential for distribution of pre-processed information.

Jan 1, 1997

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 M. Woodie

INTRODUCTION Information such as application review to choose the proper style of vibrating screen, parameters that determine the proper size of vibrating screen, engineering design information that governors proper screen design, review of topics that govern proper isolation from structural steel and other topics that dictate proper screen selection for applications will be presented in this paper. Topics like process and application information review to choose the style of screen and how material size and type influences proper type of screen selection (multi-slope, incline, horizontal, linear incline or dewatering) will also be discussed. Parameters will be reviewed that help size the screen for the application. The total amount of surface area to size a screen is critical to the overall success of a screen installation. Once proper style of screen is determined there is an engineering process that is required to design the screen to operate correctly in the environment it will be used. Finite Element Analysis, Dynamic Modeling, Field Vibration Analysis and other engineering tools will be reviewed to best implement a successful vibrating screen installation. TYPES OF SCREENS Multi-Slope Multi-Slope vibrating screens are used where sizing large amounts of tonnage on surface areas that would be smaller than conventional screening where roughly 6” (150mm) minus material is required to be sized. Occasionally larger particle sizes can be screened on the Multi-Slope machine but the effectiveness of the machine can be diminished with larger particle sizes and larger than 4” (100mm) screen opening. The most common and effective size range of screening with these machines is 2” (50mm) minus material. The Multi-Slope screen is used where particle size is not extremely important. Mineral processing, hard rock mining and industries where exact material size is not critical are best suited for this equipment. Because the aggregates industry requires very specific material sizes, the Multi-Slope screen is not suited for most aggregate screen applications. The key to the success of a Multi-Slope screen is proper material presentation at the feed end of the screen. This allows for the material to stratify quickly and disperse the fines through the screen quickly with a relatively thin bed depth at the feed end which allows the undersize material through the screen quickly.

Jan 1, 2019

By James W. Cooksley

Through the early stages of metamorphism, when diffusion is the predominant mineral forming process. there is a tendency toward homogenization of rock units; but there is also zoning resulting from differing primary lithology and structure. Later stages of metamorphism, when infiltration occurs, tend to intensify zoning within the rock mass. The above concepts have been borne out in exploration of talc deposits and skarns. Initially, geologic mapping and soil sampling are directed to understanding mineralogy and petrology. Later, seismic methods are employed to further define lithology in the subsurface. Magnetometer surveys can also define some metamorphic units efficiently. Then, drilling must ensue to confirm lithology and determine extent of mineralization.

Jan 1, 1992

By J. N. Philbrook

As with most industries, mining must now include in its plan of operation mechanisms to address a project's environmental impact. New regulations have focused attention on the potential environmental impacts of industry, particularly the handling of wastes. Modifications are currently being proposed to the Bevill Amendment. And development is ongoing of Resource Conservation and Recovery Act (RCRA) Subtitle D regulations specific to mining wastes. The result is a growing concern on the part of lenders, developers, buyers and owners regarding acquisition and ownership of mining properties. One of the most effective tools in managing the regulatory requirements is an environmental audit. An environmental audit can be a literature review to determine regulatory requirements. The audit can also take on the form of a phase-one site assessment. This is a limited investigation to determine whether there are specific

Jan 1, 1991

By K. Chandrasekaran

Carbon-in-Leach (CIL) is conventionally used in gold processing operations when preg robbing components are present in the ore. CIL process is becoming attractive even in other situations when preg robbing is not a factor. This paper discusses the situations in which the CIL circuit can be applied. The results of Leach/CIP and CIL circuits at Newmont's Mill No.2, 4 and 5 are presented for comparison. Newmont's Mill No. 4 was initially designed for a throughput of 4500 tons per day. The mill is presently operating at an average throughput of 7300 tons per day without significant changes to the original design. The design considerations of the Mill No.4 CIL circuit are discussed.

Jan 1, 1991

By M. G. Gorman

The effects of particle size, particle shape and degree of aggregation on n-dodecylamine flotation of -20 µ m quartz and glass beads were studied. A microflotation cell suitable for use with very fine particles was used in the flotation experimentation. Degree of agglomeration of particles was estimated by comparing size distributions of the quartz and beads in a dispersed system to size distributions in systems in which the collector was present. Results obtained show that in such flotation systems the fine particles are not generally present as individual particles during flotation but rather as aggregations. However, the quartz floats more readily than the beads indicating that there are some shape effects in the systems, considering the large specific surface areas of the materials it also appears that substantial amine consumption in the systems may limit flotation or lead to a requirement of greater reagent dosage for equivalent flotation to that tor larger particles.

Jan 1, 1990