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By Donald D. Murphy

My first contact with underground, bolt conveyors came when I was hired as a draftsman by the La-Del Conveyor & Manufacturing Company in 1935. At that tine relatively few nines were using haulage belt conveyors. Wore they were in use, they were usually loaded by chain or shaker type room conveyors which in turn were hand loaded at the working face. Duo to the low room tonnage, a gathering belt might receive who output of from six to eight rooms. For several years belts 26 and 30" in width were the favorites for coal mine use. Belt speeds very seldom exceeded 200 ft. per mm. at that time. Conveyor lengths for the majority of units lay between 1.000 and 2000 ft. For a number of years 25 H.P. drives were adequate for those conveyors. From 1940 until about 1950 loads and speeds went up slightly and 40 H.P. drives became the standard. Since the majority of mines were then using direct current power systems, we were able to use controllers with 3 or more steps of starting resistance. The slow belt speeds coupled with relatively long starting cycles kept the rate of acceleration low and gave us smooth, easy starts.

Jan 1, 1963

By Rongjie Kong, Shiwei Wang, Dongjiao Gui

Metal cations have significant effects on the flotation of coal and minerals. In this study, the effects of monovalent cations ( Na+ and K+) on the flotation of low-rank coal (LRC) were investigated using flotation and particle–bubble attachment experiments and through X-ray photoelectron spectroscopy (XPS) and molecular dynamics simulations. Oleic acid (OA), methyl linoleate (ML), hexadecyltrimethylammonium chloride (CTAC), ricinoleic acid (RA), and kerosene were used as flotation collectors. The flotation experiments revealed that the flotation yields of LRC improved when OA, ML, RA, CTAC, and kerosene were used in pure deionized water. However, flotation was suppressed for these collectors in the presence of K+ and Na+ ions. In contrast, when using CTAC, the flotation yield increased in the presence of these ions. Specifically, the flotation yield increased from 41.24 to 87.03% when 2.0 kg/t CTAC was used in 10 mmol/L NaCl solution. Particle–bubble adhesion experiments and XPS revealed that the hydrophilic groups of CTAC were adsorbed on the LRC surfaces by electrostatic forces, whereas the oxygen-containing functional groups of OA, ML, and RA formed hydrogen bonds with the LRC surface in pure water. Finally, the simulating result revealed that the hydrophobic ends of the OA, ML, and RA collectors hinder the flotation of LRC by adsorbing monovalent cations, whereas the adsorption of monovalent cations on the hydrophobic end of the cationic surfactant (CTAC) promotes flotation via strong electrostatic interactions.

Jan 31, 2024

By D. P. Tao, J. G. Groppo, R. Killmeyer, W. W. Wen, B. K. Parekh

Economical dewatering of ultra-fine (minus 74 m) clean coal slurry produced in column flotation to a 20 percent or lower moisture level will be an important step in successful implementation of the advanced fine coal cleaning processes. The main objective of the present study was to evaluate efficiency and effectiveness of three dewatering techniques, namely, hyperbaric, vacuum and screen bowl centrifuge, in dewatering of ultra-fine (D50 ~ 25 m) clean coal slurry produced by the `Ken-Flote' columns operating at the Powell Mountain Coal Company, St. Charles, Virginia. he hyperbaric filter using 3 bar pressure and 165o cake formation angle, provided a filter cake with 23.6percent moisture with a throughput of 800 Kg/m2-h and air consumption of 868 Nm3/t (460 scfm/t). The vacuum filter with 30 percent submergence provided a filter cake with 27.8 percent moisture with a throughput of 122 Kg/m2-h. The screen bowl centrifuge provided a dewatered product containing 32.9 percent moisture at a feed rate of 450 Kg/hr, however, the solids capture was only65 percent. Addition of 1 Kg/t of a cationic surfactant provided filter cakes with 19.1 percent, 23percent, and 34 percent moisture using hyperbaric, vacuum, and centrifuge, respectively. Similarly, addition of 0.5 Kg/ton of copper chloride lowered filter cake moisture to 20.7 percent and 24.8percent, using hyperbaric and vacuum. With the centrifuge no improvement in filter cake moisture was noted. However, use of 80 Kg/ton of `orimulsion' in the centrifuge provided dewatered product containing 26 percent moisture, and the solids capture increased from 65 to 95 percent. The dewatered product appeared dry and was easily handleable.

Jan 1, 1999

By Jorge Ferrero, Andreas Raedle, Uhland Konrad, Michael Dutton, Keivan Pak Iman, Walter Trisi

Strabag, in partnership with Arup, is constructing the Advance Tunnel for the Scarborough Subway Extension (ATSSE); a project by Metrolinx and Infrastructure Ontario (Sponsors). The 10.7 m internal diameter single bore tunnel represents a significant departure from the traditional arrangement of twin subway tunnels in North America. ATSSE is the first-time steel fibers are used to solely reinforce a tunnel of this size in Eastern Canada. This paper discusses the challenges with design and acceptance of SFRC segments and the state-of-the-art numerical models employed to check the joint performance. The advance procurement approach for TBM and PCTL’s procurement to accelerate the project schedule is also presented.

Jun 13, 2023

By E. Z. Casassa

There has been a recent revival of interest in concentrated coal/water slurries as a substi¬tute for fuel oil or for coal/oil mixtures, particularly in electric power generation. The idea is not a new one. Coal/water slurries were transported by pipeline in the U.S. in the early nineteen-sixties, and the Black Mesa coal pipeline has been in operation for several years, while in Germany, coal/water slurries were being burnt for power generation in the early nineteen-seventies, as described by Merten and Höner (1972). Since coal is not a pure substance but a carbonaceous mixture, the different chemical and physical behavior of coal/water dispersions from different deposits must be understood in order to optimize the properties of the result¬ing slurry fuels. Since minerals which are minor constituents of coal may also strongly affect slurry properties, coal chemistry may vary considerably even within a single deposit. Thus it is unlikely that there will be a single formula for optimizing the slurry properties of all coals, and even the answer for coal from a single source may change with time.

Jan 1, 1983

By Robert Giglio

Looking back over the last 150 years or so, it is not hard to see that electricity has been a primary force in shaping human development. It has been a basic ingredient in our industrial revolutions that simultaneously improved the productivity, working and living conditions within our farms, factories, hospitals, offices and homes. Today, it has become an essential part of our daily life and our future. Amazingly, we keep finding new ways to use electricity to make our lives more safe, comfortable and productive. It is a great success story of human ingenuity, achievement and development. Demand for electricity The convenience and value of electricity has not gone unnoticed by consumers. According to the U.S. Department of Energy (DOE) (Energy Information Administration, 2009), electricity is the fastest growing form of energy in the world and during the next 20 years the world will likely consume twice as much of it as it does today. In 2008, almost 20,000 terawatt hours of electricity globally were consumed (Energy Information Administration, 2009). That is enough electricity to light up more than two million baseball stadiums or power more than 11 billion computers continuously for an entire year. The United States has the dubious distinction of be-ing the largest consumer of electricity in the world with enough power to provide each American with more than 3 kW of electricity ? that is about twice the power currently available to Europeans, eight times the power available to the Chinese and more than 25 times the power available to the citizens of India (American Coal Foundation, 2009).

Jan 1, 2009

By Jack T. Work

Spiraling costs in every segment of the open-pit mining cycle is a fact of life that every operator must reckon with. The introduction of various shock absorbing devices for rotary drilling is one recent innovation that may significantly reduce overall drilling cost, increase drill availability, and lower maintenance requirements. In a recent all-inclusive test in taconite ores, shock absorbers on Bucyrus-Erie BE 60R and Gardner¬Denver GD 120 rotary drills were directly responsible for overall savings of up to $41.06 per hour. What is It? A shock absorber is simply a device installed between the rotary drive head and drill steel that cushions the two. It functions in the same manner as springs and shocks on an automobile. Some benefits associated with use of the tool are readily apparent on a daily basis; other benefits are realized over longer time intervals and through continued use. A properly designed shock absorber will: •protect the drill from severe vi¬brations, improve rock bit performance, allow application of the best weight-on-bit and rotating speed under all drilling conditions, •function effectively over a wide range of applied bit weights, • have a spring rate soft enough to perform its primary function of absorbing both rotary and vertical vibrational forces generated by rough drilling, •be reliable and subject to as little maintenance as possible, •be easy to install and remove, and • be of such an economic benefit so as to offset the added expense of its application. A shock absorbing tool developed by BJ-Hughes Inc. was used in a recent test. The "Smoothdrill" is just one of the products currently available. This unit absorbs both rotary and vertical shock loads and has no mechanical parts so lubrication is unnecessary. A rebuild of the unit consists of removing the worn rubber element and inserting a new element, an operation taking less than one hour. Minimizing Vibrations Severe vibrations on a blasthole drill operating in broken and discontinuous formations have visible effects. These vibrations often cause structural damage when allowed to' continue, resulting in fatigue cracks in the mast and related structural components in the drill. When rough running formations are encountered, drilling must be interrupted and possibly shut down. Usually, the drill operator resumes drilling using less down pressures and various rotational speeds until firmer drilling is encountered. An effective shock absorber can substantially reduce these vibrational forces so more down pressure can be applied in bad ground. It is generally accepted that longitudinal vibrations and cyclic forces are more effectively reduced if a tool is designed to incorporate a relatively "soft" shock absorber. The softness of any shock absorbing tool is best judged by its spring rate-the weight required to produce a given amount of deflection, commonly expressed in units of kg per mm or pounds per inch of deflection. All shock tools use a resilient member such as rubber springs, steel springs, fluid, or gas springs to absorb

Jan 4, 1980

By R. Sharon

Barrick Goldstrike Mines, Inc. Betze-Post open pit operations, located in northeastern Nevada, have experienced slope instability attributed to the presence of generally weak rock mass conditions, local adverse structural geology and perched groundwater. Ground movements are monitored with acombination of optical survey, extensometers, inclinometers, and time domain reflectometry (TDR).The slope monitoring system at Goldstrike includes two robotics theodolites, which provide real-time coverage for all highwall areas. Survey instruments are housed in specially designed climate controlled shelters in locations where all slopes can be observed. A “remote” computer housed with each theodolite collects data. The “base” computer, located in the mine offices, is used to access data from the remote computers via radio modem.

Jan 1, 2000

By Irwan Halim, Seung Han Kim

This paper will describe design of precast segmental tunnel lining for the Pawtucket CSO Tunnel Project in Providence, Rhode Island. The tunnel is 11,700 LF long with 30-foot finished diameter to be constructed in complex sedimentary rocks. Special features of the segments include a large keystone and no connector used on radial joints. The typical segments will be steel fiber reinforced, and hybrid segments with additional steel rebars and shear bicones will be used around the adit openings without use of any structural framing. The important design considerations will be discussed, including special 3D segment to adit connection analyses performed.

Dec 1, 2022

By A. Lashgari

Surface coal mining in the Appalachian region consumes a significant amount of energy in the form of diesel fuel and blasting agents. emission of oxides of nitrogen (Nox) from these sources represents an environmental challenge to the mining industry. this paper presents the results of research work related to determination of Nox emission of mining equipment and blasting agents, which is part of a broader industrial project conducted by the Appalachian research Initiative for environmental research (ArIeS). Data for this project are collected from an operating surface coal mine in West Virginia. the research work presented here may be used by mining professionals to aid in quantifying Nox emission and determine strategies for reducing its overall environmental impact.

Oct 1, 2013

By Reno H. Sales

The syngenetic, metamorphic water, and source bed concept theories of ore deposition proposed by Anton Gray, C, Lo Knight and others, to explain ores in sedimentary rocks, are challenged on the basis of a survey of the literature and personal observation, A hydrothermal origin for the Northern Rhodesian Copperbelt deposits is indicated by the presence of post-Roan age igneous rocks and post-gabbro mineralization, the wide distribution of ore in the various Lower Roan lithologic types, and the zoning of the copper-iron sulphlde minerals and minor elements The proposal by Gray and Knight that igneous rocks are not favorable as guides to nonferrous metal deposits, and Gray's hypothesis that the redistribution of connate waters and their dissolved metals by metamorphic processes was responsible for the emplacement of ores, are rejected as contrary to field evidence, The absence of exposed potential igneous source rocks is shown to be an invalid argument for the proponents of any syngenetic hypothesis, The common association of ore deposits with calc-alkaline intrusive rocks and their derivatives is, however, demonstrated to be convincing evidence that an exploration program based upon a magmatic theory of origin, would have found most of the important known non-ferrous metal deposits of the world, It is urged that prospecting be continued on the sound basis of accumulated knowledge of the lithologic and structural facts surrounding known ore deposits.

Jan 1, 1960

By Wern-ping N. Chen

Pressure tunnel includes water-supply tunnels and tunnels for hydroelectrical power plants. Their design principles are different from those of water/wastewater/conveyance and transportation tunnels. Though theoretical pressure tunnel design guidelines exist, a comprehensive guide to summarize these guidelines to facilitate the planning and design of a pressure tunnel program is lacking. The purpose of this paper is to fulfill this need. It first provides key pressure tunnel design concepts in hard rock environment; then, it illustrates associated final lining design principles, including the design of un-reinforced concrete lining, steel lining, and reinforced concrete lining. Design diagrams and a flowchart for the reinforced concrete lining design are provided.

Dec 1, 2022

By M. Karmis

The algorithms for the mathematical modeling to predict productivity of underground room-and-pillar mining systems are well known and documented. These algorithms consider the time-varying relationships between mining equipment for a given geometry of operations as well as other constraints. This paper presents WebConSim, a newly developed, Web-based, user-friendly computer simulation tool for the Windows environment. The simulator is easily customized for use by field engineers, planning engineers, and management and will help mine operators plan the optimum mining sequence for different mine geometries and equipment layouts. Program output includes production data and equipment utilization indices, as well as time driven event chains that can be used for virtual reality presentations.

Jan 1, 2001

By J. A. Lombardi

Acid-Minesite-Solutions (AMS) are defined as copper-containing pit lake, tailing pond, acid-mine-drainage, and heap and waste dump irrigation solutions. All of these solutions are characterized by copper, acid and water contents that have value as individual commodities. HW Process Technologies, Inc. (HWPT) has developed nano- and hyper-filtration membrane methods for the separation of copper and other base metals, acid and water from AMS. These treatments are collectively called HWPT?s Engineered Membrane Separation® (EMS®) systems. The EMS® method of copper recovery produces small volumes of higher-concentration copper solution from large-volume, copper-dilute AMS. A case study of the 4,000 gpm Cananea EMS®-AMS plant for the recovery of copper from an acid-pit-lake resource is described. The EMS® method of copper removal from AMD and tails pond waters has been bench-scale demonstrated and are described, complete with projected budgetary capital and operating costs. Additional treatments for the recovery of sulfuric acid and high-quality water from the permeate (membrane passing) waters for the above-described AMS treatments are presented, with budgetary capital and operating cost estimates. [ ]

Jan 1, 2009

By K. Kovári, G. Anagnostou

Slurry and EPB-shield tunnelling have been successfully applied worldwide in recent years. Under extremely unfavourable geological conditions, however, face instabilities may occur. The present paper aims at a better understanding of the mechanics of face failure. For the case of slurry shield, attention will be paid to the time-dependent effects associated with the infiltration of slurry into the ground ahead of the face. Related topics, such as the stand-up time and the effect of the excavation advance rate, will be discussed. In the case of an EPB-shield, a distinction will be drawn between fluid-pressure and effective pressure in the chamber. The effective pressure can be visualized as a “grain to grain” contact pressure between the muck and the ground at the face. The water pressure in the chamber reduces the hydraulic head gradient in the ground and, consequently, the seepage forces acting in front of the face. The face is thus stabilized both by the direct support of the pressurized muck and by the reduction of the seepage forces in the ground. The paper includes normalized diagrams which allow the assessment of tunnel face stability.

Jan 1, 1997

By Michael Karmis

The International Conference on Sustainable Development Indicators in the Mineral Industries(SDIMI 2003) was held May 21-23, 2003 on the island of Milos, Greece. The objective of this international conference was to assist the mining and minerals industries in their global transition to sustainable development. The main theme of the conference was the development, monitoring and assessment of sustainable development criteria for mineral operations. Emerging technologies were also presented that can assist in the development of criteria and performance indicators.

Jan 1, 2003

By John A. Reeves

The unit-train concept of moving raw materials .is considered by many railroad men as the most signifigant contribution to reducing rail freight costs since the introduction of the diesel locomotive. The idea, which involves assigning railroad equipment to only one haul and keeping the equipment rolling results in the maximum utilization of equipment. For example before the unit train was plaged in servige on coal hauled to one of Mid. Continent's customers, about 900 cars and 9 locomotives were needed to move the coal requirements for this plant, compared with. 250 cars and 6 locomotives used by the present scheduling of unit trains. If the economics of unit-train movements are to be achieved, coal companies no longer can use railroad cars as small storage bins on wheels to accumulate their coal in trainload shipments, but, rather, must build large bins which incorporate facilities for the rapid loading of railroad cars in a minimum length of time. In this manner railroad equipment is operated at a high degree of efficiency 'with consequent dollar savings. After negotiations between Mid-Continent, the customers and the Railroad, it was decided a unit train loadout and storage facility at Carbondale was required in order to reduce the delivered price of coal to the customers and thereby contribute to the reduction in the cost of manufacturing steel. Carbondale was selected as the bin site location, because the cost of constructing a railroad to Redstone could not be justified for the tonnages anticipated.

Jan 1, 1969

By P. Kim Carroll, D. Nick Tiffany, Doyl M. Fritz

Thunder Basin Coal Company received the 1987 Wyoming Excellence in Surface Mining Award for construction of the State's first major sediment control reservoir to be designed using the new settleable sol ids standard. Use of this standard resulted in construction cost savings of more than $250,000; reduced water quality monitoring; enhanced downstream channel stability because of more natural sediment loading; allowed simultaneous establishment of permanent waterfowl and fisheries habitat; and provided a quality recreational site. This article will address factors associated with the design and construction of that sediment reservoir and the benefits that were realized. (Note: This paper was originally published in the proceedings for the 1988 National Symposium on Mining, Hydro1ogy, Sedimentology and Reclamation held in Reno, Nevada, December 5-9, 1988.)

Jan 1, 1989

By X. Zhu, R. Du Plessis, J. D. Miller, D. G. Kotylar

Research on the low-potential hydrophobic state of pyrite with potassium amyl xanthate (PAX) as collector, is reported to help explain and understand the fundamental aspects of the N2TEC flotation process, which was originally developed for the improved recovery of gold from refractory auriferous sulfide ores. Typically in the N2TEC process, air is replaced by nitrogen as the flotation gas, and potassium amyl xanthate is used as collector for the reactive auriferous pyrite particles. The first N2TEC flotation process was commissioned at Lone Tree in Nevada in March 1997 and has been in operation ever since. On the basis of electrochemically controlled contact angle measurements, the low-potential, low-pH hydrophobic state of pyrite has been examined as a function of flotation variables such as pH, gas-phase composition, collector concentration and pyrite potential.

Jan 1, 2000

By C. H. Bucknam

Principles of Green Chemistry provide useful guidance for sustainable mineral process development. Laboratory bench scale testing was carried out using pregnant cyanide leach solutions, and a number of commercially available mercury precipitation reagents were compared using jar testing to determine the most efficient and selective reagents for mercury precipitation. The most efficient reagent identified was sodium polymeric thiocarbonate (NaPTC).Coagulation experiments with fine diatomaceous earth resulted in a stable precipitate, with good settling properties. On line monitoring of the mercury in solution is recommended for process implementation to conserve reagent removing approximately 90-95% of the mercury with minimal silver and negligible gold losses.

Jan 1, 2004