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By C. D. Messelt

The Bureau of Mines investigated the application of a diffusion model to sintering rate data developed for lithium titanium ferrite. The data were obtained by sintering pressed pellets under identical conditions for various times up to 11 hours. Stereological measurements were made on polished sections, and sintering rates were calculated. A model for intermediate stage sintering was fitted to the stereological data. This procedure produced a method by which these type data could be used to study the relative importance of volume and grain-boundary diffusion under a variety of sintering conditions.

Jan 1, 1979

By Michael Cruickshank

Bob Woolsey was born in 1936 in the state of Georgia and grew up to be a man of great integrity, vitality, wisdom and charm, totally neutral on matters of race, gender, and religion. A true Southern Gentleman in every sense of the word. His passing on July 9, 2008, the victim of an automobile collision, left an empty space in the hearts of his family, and his many friends and colleagues throughout the globe. The posthumous award of the Moore Medal of the International Marine Minerals Society, to Dr. J. Robert Woolsey for Excellence in the Development of Marine Minerals, is a well deserved tribute to this man who spent the last 30 years of his professional career heavily involved in research and development of marine minerals on an international basis. He first came to my attention in Burma in 1979 where, as a newly appointed technical advisor to the United Nations Development Program Offshore Exploration for Tin, I had to fill the shoes of an almost legendary figure "Dr. Bob", who accompanied by his wife Maxine had spent the previous two years initiating the program. Bob had planned to completion the construction in Singapore of a unique drilling vessel the RV Sea Drill, a spud anchored, twin-hulled barge, mounted with a Becker Drill, and designed for sampling alluvial tin deposits in the coastal waters of the Mergui Archipelago in the Andaman Sea, off Tenasserim. He had also designed and built, with the help of his side -kick Bruce Jernigan, a barge mounted dressing plant for reducing and concentrating the drill samples. The adventures of Dr. Bob in transporting the equipment to the drilling site in monsoon weather and the transfer of the drill barge from the Malaysian port of Ranong across the strait to Victoria Point in Burma with a mutinous crew will remain in the hearts and minds of his Burmese colleagues for many a long year. On his return to the States he joined, in 1980, the faculty of the University of Mississippi (UM) as assistant Professor of Geology and Geological Engineering. His prior experience in private industry and the United Nations had focused on marine mineral resources and related environmental engineering projects in Africa, South America, the Mediterranean, the South Pacific as well as south east Asia, working with dredges, mining for alluvial tin, gold, diamonds and industrial minerals. He continued to work in the area of marine minerals at UM, making a name for himself as Director of the Mississippi Mineral Resources Institute (MMRI).

Jan 1, 2008

By B. Elevli

The aim of this paper is to demonstrate the implementation of multicriteria analysis in selection of the most suitable underground ore transport system for a chromite mine in Turkey. The related problem includes five possible ore transport systems and six criteria to evaluate them. The adopted evaluation and ranking method for this study is PROMETHEE. PROMETHEE I revealed a partial order of alternatives where incomparability exists. PROMETHEE II gave the absolute ordering of alternatives. The results have shown that the PROMETHEE method can be successfully used in solving mining engineering problems. Keywords: multi-objective, decision analysis, mining, ore transport system

Jan 1, 2004

By B. W. Gandrud

[This report presents the data of one of a series of investigations of the washability of Alabama coals as indicated by float-and-sink tests mode by the Bureau of Fines at the Southern Experiment Station in cooperation with the University of Alabama and Alabama coal producers. The Klandyke mine, operated by the Blocton Mining Co., is about 1 mile eat of Vest Blocton, Bibb County, Ala., floor the southwestern, extremity of the Cahaba coal field. The Bureau of Mines already has published three reports that deal with the, washability of Cahaba coals - one a washability study of the Clark bed at Marvel4/ one on the tabling of fine coal from the Thompson and Woodstock beds5/, and the third a washability study of the Henry Ellen bed at Acmar6/.]

Jan 1, 1939

By A. E. Ketler

A second generation lighting system was installed in the Greenwich Collieries longwall. This report describes the hardware, installation, maintenance, and final results of the program.

Jan 1, 1978

Bacterial leaching represents an unusual problem in biochemical engineering, because the substrate for bacterial growth is not supplied directly, but is a product of another reaction, the leaching of mineral particles. Leaching arises from the bacterial oxidation of ferrous ions to ferric ions, which in turn oxidize the mineral. For the bacterial dissolution of pyrite, these reactions are: [ ] (Y represents a stoichiometric yield factor, and N represents the amount of bacteria.) Equations [1] and [2] represent a cyclic auto-catalytic system since more ferric ions are added to the system with an increase in the extent of leaching.

Jan 1, 2000

By Edward M. Kawenski

Float dust deposits in return airways in bituminous coal and lignite mines present a special explosion hazard. Research is in progress at the Bureau of Mines experimental coal mine to evaluate the degree of the hazard and to develop measures for preventing dissemination of dust into the ventilating air current. To determine the extent of this hazard prevailing in operating coal mines, 711 dust samples were collected in 50 mines located in the major coal fields of the United States. The mean quantity of coal and the incombustible content of the dust in the samples were determined. The term "float dust" is used to designate particles smaller than 74 microns in diameter (particles passing a No. 200 sieve) which have settled from the air current. Dust usually found in roadways and in working places is coarser than float dust, and is termed "coarse dust" (particles passing a No. 20 sieve). Variations in amount and incombustible content of coarse dust in a midwestern mine were studied previously.

Jan 1, 1963

By J. F. Wilson

An experimental investigation has been made of gas-driven slug displacements in a system of high gas saturation to evaluate the process for use in a California reservoir. Fluid compositions, temperature, pressure and core permeability duplicated reservoir conditions as closely as possible. The temperature was above the critical of the slug materials. The slug composition required for 100 per cent oil recovery in the linear flow systems was found to agree with that determined from equilibrium phase studies. A qualitative theory for the slug displacement of two-phase systems is proposed and found to be in general agreement with the observed flow behavior. The theory predicts that the length of the reservoir fluid-slug transition Zone will increase with increased initial gas saturation and decrease with increased oil swelling accompanying the composition change from reservoir oil to the critical composition. The precipitation of small amounts of an asphaltic phase during the formation of the transition zone had no adverse effects on the flow behavior of otherwise miscible systems. INTRODUCTION Despite the large number of recent publications relating to oil recovery by miscible displacement, little information is available concerning the behavior of crude oil-natural gas systems at conditions likely to be encountered in field application. The laboratory data reported here were obtained during an investigation of the possibility of using a gas-driven LPG slug in a partially depleted California reservoir. Seven gas-driven slug displacements employing slugs of different compositions and sizes were made in 26- to 27-ft long sandstone cores. The equilibrium phase behavior of the systems was also determined. The features of primary interest in this study are the following. 1. Data were obtained on the displacement of reservoir fluids at reservoir conditions. 2. A high gas saturation existed in the long cores at the start of the displacements. 3. The temperature of the studies was above the critical of the slug materials. 4. A comparison between the flow behavior and equilibrium phase behavior, as illustrated by a pseudo-ternary phase diagram, is afforded for a system of considerable complexity. THEORY Phase Behavior The use of the pseudo-ternary phase diagram to illustrate the phase behavior in miscible displacements has been discussed by Clark, Schultz and Shearin. Sie-vert, Dew and Conley and Arnold, Stone and Luffel' have presented both phase equilibrium and flow data for true ternary systems. For the true ternary, the application of the theory is straight-forward; for a reservoir system represented as a ternary, the theory undoubtedly gives a qualitatively correct picture. One purpose of this investigation was to see if the pseudo-ternary phase diagram could be used to predict with reasonable accuracy the conditions necessary for miscible displacements with actual reservoir systems. MiscIBLE Displacement of Two-Phase System A large number of papers "I3 have treated the miscible displacement of a single-phase fluid from both an experimental and a theoretical viewpoint. However, the normal field application of the process will be in a partially depleted reservoir. Often the state of the system will be such that the mobility of the gas phase is greater

By Hugo E. Camargo

Noise Induced Hearing Loss is the most common occupational disease in the U.S. and of paramount importance in the mining industry. According to data for 2006 from the Mine Safety and Health Administration (MSHA), Continuous Miner operators accounted for 30.2% of underground mining equipment operators with noise doses exceeding the Permissible Exposure Limit (PEL). This figure becomes more significant considering that 49% of the 2006 national underground coal production was extracted using continuous mining methods. Thus, there is a clear need to reduce the sound radiated by Continuous Mining Machines. The first step towards efficient noise control of a Continuous Mining Machine requires identification of the various noise sources under controlled operating conditions. To this end, a 42-microphone phased array was used in conjunction with 4 reference microphones to sample the acoustic field of a machine in the Hemi-anechoic chamber of the Pittsburgh Research Laboratory. These data were processed using a frequency-domain beamforming algorithm to obtain acoustic maps of 5 sides of the machine. The focus of the test was on the conveyor noise since previous studies showed that operation of the conveyor is the most important contributor to the sound radiated by the machine. From the acoustic maps, the following potential areas for noise control were identified, and included: chain-tail-roller interaction, chain flight tip-side board interaction, and chain-upper deck interaction.

Jan 1, 2008

By I. Liebman

The Bureau of Mines conducted research to develop triggered barrier systems for protection against gas explosions that can occur in underground coal mines during the use of continuous miners. Several extinguishing agents were tested in barriers at a simulated mine face. Water, powered by pressurized nitrogen, was found to be efficient in stopping fully developed gas explosions, but it had little effect against the explosion during its incipient stage. Hybrid combinations of currently known extinguishants, however, were successful against incipient explosions. Three hybrids that were developed and tested consisted of Halon 1301, combined with either an aqueous foam solution, water, or a dry chemical powder. The three hybrids were found to be more efficient than any constituent alone. Results of the tests point to a synergism between the hybrid components, and indicate that the Halon aids in dispersing its constituent and also converts the aqueous foam solution into a stable fine foam and the water into fine drops.

Jan 1, 1978

By Michael Peterson, Robert Davinroy, Robert Rapp, Gregory Hempen, David Herzog, Thomas Keevin

Fish sampling in a deep-water, high velocity, environment is extremely difficult. Conventional techniques such as electro-fishing and netting have been limited to depths generally less than 7 meters (m) and velocities below 1 meter per second (mps). The goal of our study was to sample a bendway weir field on the Mississippi River to assess the effects of the weir field on the fishery. In a bendway weir field, depths can exceed 20 m, and velocities can exceed 3 mps, making conventional sampling techniques inefficient.

Jan 1, 2002

By T Hirsi, M Weatherseed, T Ritasalo

Cooling tower design has not advanced significantly in the last decade. Recognising this, Outotec has developed an innovative horizontal outflow cooling tower with increased performance compared to conventional design cooling towers.Outotec® Cooling Towers operate today in applications such as spent electrolyte cooling in zinc plants and for gypsum removal before copper solvent extraction. In such applications the use of this latest design has enabled increased production and lower maintenance costs in the downstream operations.In actual operations, the cooling performance has been confirmed at start-up, and has demonstrated that the towers operate in accordance with the CFD modelling. In the last three years these towers have proven themselves in commercial operation to operate with high efficiency and availability.This case study will outline comparative data, collected over two years at a site where both Outotec and conventional cooling towers are operating. The data shows that Outotec cooling towers require less than half the maintenance time of conventional cooling towers, when adjusted to a total solution flow basis. A close partnership approach with the site has allowed continual development, ensuring high availability and high performance.Experience with previous cooling tower installations guided the development of maintenance philosophies and procedures; this resulted in a design where maintenance intensive components were accessible from the top of the cooling tower. This allows safe access to components and maintenance with little or no downtime.CITATION:Hirsi, T, Ritasalo, T and Weatherseed, M, 2015. Improving cooling tower performance with innovative horizontal outflow design, in Proceedings MetPlant 2015, pp 396–402 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By E. R. Maize

[In report of Investigations 3452,5/ baling with roof movement in the Crucible mine, reference was made do to the fact tart timber decay was being studied at the time of writing. This roper, written after completion of that study, describes s the work and summarizes the data obtained. When the study of roof movement as begun at Crucible two ideas were advanced on decay Of timber by some of the officials: (1) That timber decay vas unusually rapid in the Crucible mine, and (2) that timber coated with rock dust decayed more rapidly than those teat were not so coated. There yore no records by which these ideas could be tested, and it appeared wise to make a limited; investigation particularly of the effect of rock dusting on decay, as rock dusting is an important means of preventing coal-dust explosions.]

Jan 1, 1940

By Lewis Martin

Whereas many researchers and mine engineers have conducted tests using different types of grout, grout ratios, and physical modifications of the cable to determine cable bolt load characteristics, few studies have been conducted on cables fitted with internal instruments. Those studies that have been done have concentrated on cable behavior averaged over significant cable lengths. Researchers at the Spokane Research Laboratory (SRL) of the National Institute for Occupational Safety and Health in Spokane, WA, are investigating the physical properties of cable bolts by replacing the conventional king wire with a modified king wire on which strain gauges have been installed . This paper documents test results on these modified cable bolts. Three tests were conducted at SRL on 1.83-m-long cables grouted into two 0.91-m-long pull-tube assemblies. Load along the cable was monitored with 20 strain gauges installed along the length of the cable. The instrumented cable bolt provided reproducible point measurements of cable load as opposed to load measurements averaged over significant cable lengths. Such point measurements can assist in interpreting the influence of cable confinement, grout quality, rock mass stiffness, and other factors. The instrumented cable bolt is a practical field and research tool because it can predict point loading along the cable and thereby allow interpolation of maximum possible loads on a cable.

May 1, 2002

The recent boom in the mining industry has lead to some unique challenges in successfully operating processing plants. With high turn-over rates of both operators and technical staff, and many experienced personnel leaving regional sites for city based jobs there is often an onsite knowledge vacuum and this in turn puts pressure on both site training departments and senior metallurgists to provide the relevant skills to the continuous stream of new staff. Frequently both operators and new metallurgists are instructed on a æhow-toÆ basis rather than giving them the understanding as to why tasks are performed and decisions are made. This paper has been written with the plant operator and metallurgist in mind and aims to provide suitable material to be incorporated into a site training manual. Topics have been broadly divided into the following categories: factors that operational staff can control; including pulp density, air addition rate, froth depth, particle size and reagent type and use; factors that operational staff cannot control; providing general information on bubble size, froth stability, pulp chemistry and the mechanical effects of the rotor/stator system; and process improvements. Each topic is discussed with a view to clarifying the key process variables that need to be understood and optimised in an industrial operating plant.

Jan 1, 2009

By J. Nell

An overview is given of the matte melting process used for the beneficiation of South African platinum group metal (PGM) ores. Most producers use six-electrode furnaces to melt the concentrate and Pierce Smith converters to oxidize excess iron sulphide from the furnace matte. Concentrates from two reef types (the so-called Merensky and UG-2 reefs) dominate the feedstock supply. Concentrate from the Merensky Reef is low in chromium and does not pose significant melting problems. Concentrates from the UG-2reef contain much higher levels of chromium, which results in the formation of chromium-rich spinels during melting. This is attributed to the low solubility of chromium in furnace slag under typical operating conditions (an oxygen partial pressure of 10-8?10-9bar at temperatures of 1550°C to 1600°C). During the converting process, care is needed to avoid excessively oxidizing conditions, which result in cobalt, nickel and copper losses to the slag. High nickel losses result in the formation of Fe2NiO4 (trevorite), which often forms solid solutions with FeCr2O4and Fe3O4. In future, the main challenge in the processing of South African PGM ores will be to cope with ever-increasing levels of chromium in the concentrate. A short-term solution to the problem would be to melt the concentrate under slightly reducing conditions to promote the formation of CrO, which is more soluble in the slag than Cr2O3.A longer-term solution to the problem would be to abandon the current matte-smelting process in favour of an alloy-based process, which would offer total flexibility with respect to the amount of chromium that can be tolerated in the feed. Keywords: Merensky, UG-2, furnace, slag, matte, converting, spinel, chromium

Jan 1, 2004

By Kim B. Shedd

The U.S. Bureau of Mines Particulate Mineralogy Unit examined the habits of six zeolite minerals commonly occurring in domestic zeolite deposits. Mineral habit is of interest because current theory on the potential for sarcoma production in test animals emphasizes the size and shape of mineral particles, without regard to composition or structure. A scanning electron microscopic study revealed that, of these six minerals, only mordenite and erionite crystallized in acicular to fibrous habits, The fibrous varieties of these two minerals were characterized by size and shape on the transmission electron microscope, and their dimensions were compared with those of asbestos and amphibole cleavage fragments. When comminuted, these two minerals possess "fibrosity indices" similar to those of amphibole cleavage fragments. One sample, a rare woolly erionite, has uniform widths, large aspect ratios, and a "fibrosity index" similar to those of asbestos.

Jan 1, 1982

By C Placzek, E Beattie, K Blake

Channel iron deposits (CID) consist of ferruginous chemical sediments, and are an unusual subset of Phanerozoic ooidal ironstone deposits almost unique to the Pilbara, where they constitute around 19 per cent of the Pilbara’s iron ore exports. These deposits occupy many of the ancestral river channels of the Pilbara region, especially the Robe River palaeochannels, incising and meandering through the Precambrian banded iron formations (BIF) of the Hamersley Group and the underlying Fortescue Volcanics.This paper explores the factors underlying geochemical variation in CID, particularly the chemical properties of goethite. The selected deposits in the western Robe palaeochannel and its tributaries show little or no secondary reworking by later water tables. There is a total absence of aluminosilicate clays with all the deleterious elements such as aluminium and silica. Instead, these are associated with the goethite mineral lattice, either within or adsorbed to the cortices of pelletoids.A thickly vegetated environment, and the presence of the Maddina Volcanics as potential source rocks for these western Robe CID is offered as an explanation for relatively high aluminium in the deposits studied, and, in turn, as the reason most parts of the palaeochannel are preserved as inverted topography.CITATION:Beattie, E, Placzek, C and Blake, K, 2017. Dirty goethite – a geochemical characterisation of some western Robe River channel iron deposits, in Proceedings Iron Ore 2017, pp 489–502 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Floyd C. Bossard

Major air-cooling facilities have been installed and are operating underground in U.S. copper mines (at Butte, Montana and Superior, Arizona), South African gold mines, European coal mines, Zambian copper mines, Kolar gold mints in India, Coeur d'Alene mines of Idaho, plus other locations. Mining districts that utilize spot cooling and local air-cooling facilities would increase the above listing many times. The principal objectives of underground mine air cooling systems are to; 1. Extract heat and water vapor from the mine air and provide for their removal from the mine via (a) water pumped to surface or (b) discharged mine exhaust air. 2. Provide acceptable artificial ambient conditions for efficient working mine development and production areas. 3. Recondition used air, thus supplementing the limited mine ventilation balance. In deep South African gold mines, when rock temperatures exceed about 105°F, cooling of underground air becomes necessary for the poorly ventilated sections of the mine. By U.S. standards, air conditioning in poorly ventilated mines usually commences when the virgin rock temperature exceeds 100°F. On the other hand, well ventilated deep vein-type mines in the U.S. have been able to forego general cooling of mine air until the mines have been extended to such depths that the virgin wallrock temperatures have exceeded 115° - 120°F. It must be noted that spot-cooling of selected development headings may be required in many mines where rock temperatures exceed 100°F. Such local air-cooling practices permit the driving of long headings for exploration or extended development prior to holings which result in establishment of primary ventilation circuitry. The following summary reports on current practices of cooling and dehumidifying mine air. General system descriptions with important details will hopefully permit the reader to gain an understanding of the subject. A list of references is provided for this serious investigator who desires a more thorough knowledge-base and who is responsible for the design of a mine air-cooling system.

Jan 1, 1973

The excavation of ramps and tunnels often requires high-speed development with (or without) the use of high-energy mining equipment such as loaders, dump trucks, TBMs and roadheaders. This high-speed development creates a challenge in terms of providing a safe and productive working environment. For example, heat from continuously exposed surrounding rock, heat from broken rock, heat generated by mining equipment, potential in flows of hot ground water, pollution from associated diesel equipment and the distance of the advancing face from fresh through-ventilation all have to be taken into account when designing ventilation systems for high-speed ramp and tunnel developments. This paper discusses methods of achieving acceptable environments at the face and along the length of the tunnel. The methodology has been successfully implemented in the development of long (up to 20 km) TBM drives in the Lesotho Highlands Project and in mining projects in hot rock using drill and blast methods as well as mechanized methods using continuous miners and roadheaders. The determination of heat loads includes calculation of the heat flow within the surrounding rock, evaluation of the operating cycle of the equipment and the contribution to the overall heat load of the broken rock as it travels out of the tunnel. The determination of heat loads from surrounding rock in new tunnels required a modification of the algorithms generally used for established excavations. The paper also examines the use of, for example, mobile duct and fan systems to ensure that fresh air is delivered to the specific areas where workers are located.

Jan 1, 2000