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By J. D. Noll, J. A. Organiscak, A. B. Cecala

Significant strides have been made in optimizing the design of filtration and pressurization systems used on the enclosed cabs of mobile mining equipment to reduce respirable dust and provide the best air quality to the equipment operators. Considering all of the advances made in this area, one aspect that still needed to be evaluated was a comparison of the efficiencies of the different filters used in these systems. As high-efficiency particulate arrestance (HEPA) filters provide the highest filtering efficiency, the general assumption would be that they would also provide the greatest level of protection to workers. Researchers for the U.S. National Institute for Occupational Safety and Health (NIOSH) speculated, based upon a previous laboratory study, that filters with minimum efficiency reporting value, or MERV rating, of 16 may be a more appropriate choice than HEPA filters in most cases for the mining industry. A study was therefore performed comparing HEPA and MERV 16 filters on two kinds of underground limestone mining equipment, a roof bolter and a face drill, to evaluate this theory. Testing showed that, at the 95-percent confidence level, there was no statistical difference between the efficiencies of the two types of filters on the two kinds of mining equipment. As the MERV 16 filters were less restrictive, provided greater airflow and cab pressurization, cost less and required less-frequent replacement than the HEPA filters, the MERV 16 filters were concluded to be the optimal choice for both the roof bolter and the face drill in this comparative analysis case study. Another key finding of this study is the substantial improvement in the effectiveness of filtration and pressurization systems when using a final filter design.

Aug 1, 2016

By A Maldonado, A Robert, K G. Mercer

The Hamersley Group in the Pilbara, Western Australia, consist of interlayered banded iron formation (BIF) and shale host rock formations within which a large number of open pit iron ore mines have been established. The slope stability of most of the mining excavations developed within these formations is controlled by the relatively low shear strength of the shale groups and shale bands, which are the weakest rock types. Shale formations range from fresh to highly weathered and are generally highly fissile when fresh, and clayey when weathered. An accurate understanding of the shear strength of these materials across the entire weathering continuum is therefore a key importance for assessing the slope stability of these mines.Historically defect laboratory testing results for the Pilbara mines have been analysed mechanically using direct shear testing (DST) to measure a number of geotechnical characteristics of the rock bedding and defects. This paper sets out the current practice in the industry in terms of the laboratory testing and presents a possible application of hyperspectral data to empirically correlate the shear strength of shale bedding with the relative mineralogy abundance on the bedding surface. This was achieved by creating both hyperspectral and geotechnical data sets for the same samples.In the study the shale samples were separated into three distinct assemblages: iron oxide + kaolinite, iron oxide + white mica + kaolinite, white mica + kaolinite, which had 40, nine and two samples respectively. Analysing these assemblages alongside DST data showed that samples with white mica had reduced non-variable shear strength, whereas samples with iron oxide + kaolinite had an overall higher shear strength but with a greater variance. It is inferred that the reduced shear strength in the white mica samples is due to the sheet (or plate) like structure of the mineral, giving it a weak stress plane. Confidence in the trends observed can be reinforced by expanding the data set in future works. The investigation also includes a discussion on weathering grade and addresses the question as to whether mineralogy abundances influence these characteristics in Hamersley shales.CITATION:Maldonado, A, Mercer, K G and Robert, A, 2017. The relationship between mineralogy and shear strength of Pilbara Hamersley Group shales across the weathering spectrum, in Proceedings Iron Ore 2017, pp 423–430 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By E Ah Mu and C R Lilley, A D. Campbell

Cave propagation is a complex process due to interacting variables such as mine geometry, rock mass heterogeneity and complex structural networks and stress fields. The Ernest Henry sublevel cave (SLC) is directly below an open pit, which provided an opportunity to observe and measure rock mass failure as the cave initiated and propagated through the pit wall. This paper describes interaction between the open pit and SLC as well as rock mass failure mechanisms observed from the start of the SLC to surface breakthrough.Cave propagation and slope failure mechanisms were found to be governed by intermediate structures, while the cave shape was largely controlled by cave-scale faults. The open pit, production-level geometry and production draw strategy were also important factors for cave and subsidence growth. Cave propagation was episodic and asymmetric in shape due to the orientation and relative position of geological structures, combined with the effects of the increasing SLC geometry and drawdown from the underlying production levels. The precursors and failure mechanism of a 2.5 Mt wall collapse are also reviewed in detail.Cave growth was simulated using a 3D, non-linear, discontinuum finite element model coupled with Newtonian Cellular Automata. Model results are compared to field observations and monitoring data to determine the accuracy of forecasts and compared models versus actual rock mass response during cave propagation.CITATION:Campbell, A D, Ah Mu, E and Lilley, C R, 2016. Cave propagation and open pit interaction at the Ernest Henry Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 311–318 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Edward L. McHugh

The appraisal of mineral resources of the Challis National Forest, Idaho, by the U.S. Bureau of Mines, was made so that the mineral resources of the forest could be appropiately considered in land use planning. Information from this study is intended to tip the U.S. Forest Service to incorporate mineral resource data into forest plans The study was done in conjunction with the U.S. Geological Survey, which released a companion report on the geology and mineral potential of the Challis National Forest in 1989. This summary report is derived from a more detailed USBM Open-File Report (MLA 6-91) that includes descriptions of mines and prospects, commodity profiles, and development cost models. Since the 1860's mines within the Challis National Forest have produced mineral commodities worth more than $590 million at current (1989) commodity prices. Identified mineral resources have a gross value of about $2 billion at current prices, including 8 strategic or critical minerals. The U.S. Bureau of Mines study identified and described 723 active and inactive mineral properties within the forest. Mineral properties with identified resources were evaluate to determine their economic significance, and an assessment was made of the feasibility of mineral development. Of the 2,516,191 acres in the Challis National Forest, about 390,000 acres were classified as having mining development interest. Commercially important mineral production, mainly of molybdenum, gold, and silver from the Challis National Forest is likely for the foreseeable future.

Jan 1, 1991

By A Hamanaka

EGAT Mae Moh Lignite Mine in Thailand produces about 16 Mt of lignite annually from open-cut mining. The coal is used to generate 2400 MW of electricity. In the near future, however, the coal must be extracted from underground at 400 - 500 m deep from the surface. The problem is the thickness of the coal seams. There are two coal seams that are about 25 m thick with 20 - 25 m of interburden between them.In order to investigate thick seam mining systems and propose a new mining system in ultra-thick coal seams in Thailand, a joint research group was established by Japanese and Thai researchers and mining engineers in early 2009. This paper describes conventional underground mining systems and underground coal gasification for thick coal seams and discusses the applicable coal mining systems to this mine. Then, this paper proposes an innovative underground coal mining system for thick coal seam, ‘eco-friendly underground coal mining system which consists of the utilisation of flyash and CO2 storage’.

Nov 22, 2011

By J. L. Bowlby

Introduction In the following discussion, boiler-feed and mine waters will be considered from the point of view of the problems arising from the chemical nature of the mineral and gaseous impurities they contain. The theories underlying some of these problems will be reviewed for the purpose of getting a clearer concept of the problems themselves. Certain terms of a chemical nature, necessary to the discussion, will be explained on the assumption that they are not generally familiar to mining engineers. Finally, an attempt will be made to correlate theory and practice, with the abject of establishing certain limits to factors relevant to the problems, and to show that these limits are justified by practical experience. The general problems occasioned by the presence of mineral and gaseous impurities in boiler-feed and mine waters are: (1) Scale formation and corrosion in boiler systems. (2) Corrosion of mine pumps and pump fittings. These will be discussed separately. Boiler Scale Typical analyses of waters available for use in steam power-plants are given in the accompanying Table (Table I). All analytical data are expressed in grains per Imperial gallon. The bicarbonates of calcium and magnesium in the raw waters are shown as normal carbonates in the Table. Substances in the first five rows constitute the encrusting solids. All the waters listed in Table I would be classified as 'very good' in the schedule of classification for boiler waters adopted by the American Association of Railway Chemists in 1887. In spite of this classification, however, the waters contain sufficient encrusting solids to cause serious scale trouble after prolonged evaporation.

Jan 1, 1934

By Matthew T. Mowry

As the mining industry continues to hire young professionals to supplant the growing number of retirees, a well-developed engineering curriculum, coupled with practical, real-world training, can prepare mining engineering graduates to make meaningful contributions in the industry. Successful companies can be measured not only by their reserve base and annual production but also by their retention of mining engineering graduates with zero to five years of operational experience. My personal experience in the industry during the last five years has been varied and rewarding. The knowledge and experience I have gained have taught me valuable lessons that prepared me for my current role.

Nov 1, 2013

By J. P. Coughlin

The U.S. Bureau of Mines has developed a monitoring system that acquires and analyzes data for use in determining the conditions that may precede mountain bumps in coal mines. Based on a UNIX workstation linked to an array of geophones in a working longwall operation, the system captures complete waveforms of microseismic events and simultaneously obtains continuous samples of the voltage levels of each geophone. Event rates and locations are calculated and displayed in real time on the UNIX workstation, which is situated in an underground instrumentation room. These results also are transmitted from the workstation to a display computer near the longwall face. The system runs continuously and has the capability to acquire, analyze, display, and archive microseismic (transient) data and single point data, such as closure and pressure changes, simultaneously.

Jan 1, 1993

By Dilip I. Patel, Jesus Schabib, W. Allen Mawr, Daniel A. Louis

East Side Access (ESA) will extend Long Island Rail Road into midtown Manhattan via 11 km of tunnels, a new terminal station and associated rail support facilities. The hard-rock tunneling in Manhattan will traverse under Park Avenue and some of the most historically and commercially significant real estate in the world. The soft-ground tunneling in Queens will traverse beneath Amtrak’s Sunnyside Yard and the Harold Inter locking, the busiest rail interlocking in North America. This paper details ESA’s program-wide geo-instrumentation monitoring system for obtaining, processing and presenting all geotechnical monitoring data. Data streams will be real-time, such as from automated total stations, and manually read, such as from optical survey instruments and handheld data loggers. All data will be input into a web-based Geo-Instrumentation Data Management System, which will be accessible to project stake holders via ESA’s intranet or via the Internet using remote access controls.

Jan 1, 2007

By E. D. Gardner

This is one of a series of papers describing mining and related subjects affecting mining in western mining districts and mineralized areas. The parts of this paper pertaining to current production, mining and milling methods and practices, and general conditions affecting mining were collected principally during a field survey made in May 1935. Some original data obtained on previous visits to the area are also included. The history, geological background, and past production of the mines and district are largely abstracted from previous publications, for which due credit is given later in the test. The principal districts in the Black Mountains are the Oatman or San Francisco and the Union Pass or Katherine. This range contains the principal producing mines of the State, in which gold is the only important metal. Although the total production of gold is relatively small as compared to other districts where the precious metals are obtained as a by-product in copper min¬ing, the area is one of considerable economic importance to the State.

Jan 1, 1936

By Theodore L. Turner

This Bureau of Mines report describes calcination of kaolinitic clay in a direct-fired 2-1/2- by 24-ft rotary kiln at 750° and 775° C. Methods for preparing kaolin feed materials and characterization of calcined products are discussed. Approximately 99 pct of the alumina in a typical eastern Georgia kaolin was soluble in HC1 after calcination at either 750° or 775° C.

Jan 1, 1982

By W. William Culver

James Douglas became known in the nineteenth century for two reasons fundamental to his mining career: (1) his experimental work with copper hydrometallurgy, and (2) his grasp of the idea that the quantity of copper ore matters more than the quality. On the first reason, there is a moment for any technology that’s critically important—when it moves from an area of scientific interest to one that companies are founded on. This paper examines the original 1869 Hunt and Douglas Copper Process in the context of science and engineering as they were in the 1860 and 1870s. It was a “humid” process, developed at Quebec’s Harvey Hill Mine. Chemically, the Hunt and Douglas vat leaching process succeeded, but not the original companies using it. On Douglas’ understanding of ore quality versus quantity, luck had it that the first company to field test the Hunt and Douglas Copper Process was in Chile. The Hunt and Douglas patent made that transition from experimental model to operational plant in 1870 when the Compañia de Minas de la Invernada was organized in Valparaíso. As a joint-stock company, Invernada spread the risk of investing in the revolutionary, but untested, Hunt and Douglas Process. The company brought Douglas to Chile as a consultant in 1871. His experience with hydrometallurgy, combined with what he learned about the copper business while in Chile, set him off on a career in metal mining that both surprised Douglas and made him wealthy.

By S. L. George

The semi-solid metal casting process results in a unique solidification path. The microstructural features that were identified during the characterization of the as-cast microstructure, were used as evidence of the process history in order to determine the solidification path followed during the evolution of the microstructure. The morphology of the grains was characterized using SEM and the extent and distribution of the elemental segregation within the grain structure was analysed using EDS. Keywords Semi-solid casting, solidification path, segregation.

Jan 1, 2011

By A. Karadogan, G. Tuncer, A. Kahriman

Determination of optimal blast parameters have been the priority act for blasters on the field due to financial and technical properties of the operation. Therefore many researchs were done to establish a general formula for many years. These intends could reach some empirical and numerical design frames consisting the rock, geology and explosives properties. Blasting parameters have to be adjusted according to the desired fragmentation rate especially on the mines where particle size distrubition after blasting has a great importance. Therefore the blast designs have to be evaluated considering the particle size distribution after the blasts. The Kuz-Ram model which was modified by Cunningham is one of the tools for estimating the particle size. Although it doesn’t give an accurate result, it can be very succesful on modifying the blasting design parameters by establishing a back correlation between the blasting parameters and the exact particle size distribution results which can be easily achieved by digital image processing system. Within the scope of this study, the particle size distribution after blasting was assessed by Split-Desktop digital image processing system and bench blasting parameters were studied considering the desired particle size distribution at Espey colemanite mine using Kuz-Ram and digital image processing system combination to determine the specific blasting parameters for this site.

Jan 1, 2005

By K L. Temel, W P. Player

The underlying message of this paper is that investment in prospecting, exploration and mining in New Zealand is welcomed. The Government's policy with respect to Crown owned minerals is for continuing investment in prospecting, exploration and mining which is in accordance with good exploration or mining practice. To encourage continued investment requires a business-friendly environment. Government policies and initiatives to enhance the business environment for the minerals and coal exploration and mining industries are discussed in this paper. As well, new initiatives under consideration, which have the purpose of enhancing the investment environment, are discussed.

Jan 1, 1997

By Robert E. McIvor

"The design/optimization of the pump and cyclones to maximize grinding circuit efficiency first requires a concise understanding of, and clearly defined specifications for, desired grinding circuit performance. Subsequently, the pump and cyclone performances that provide the desired grinding circuit performance can be defined. Once the performance requirements of each process unit are determined, selection of physical equipment parameters that will deliver those performances can be carried out.The Functional Performance Equation shows that there are two distinct efficiencies in closed circuit ball milling. One of these, “Circuit Classification System Efficiency” (CSE), is the fraction of “coarse” material inside the ball mill upon which grinding energy is deliberately expended, versus the remaining fraction of “fines” or finished size material inside the mill, upon which grinding energy is wasted (on over-grinding). The role of the pump and cyclones is to maximize CSE, which is the desired grinding circuit performance. The obtainable target CSE for any given circuit can be estimated, for example, by referring to a plant data base of CSE’s. Design/optimization guidelines then allow us to specify the pump and cyclone performances that will achieve the target CSE.This paper outlines the step-by-step, systematic method of pump and cyclone selection which maximizes CSE. Numerous examples of its successful application are provided.THE FUNCTIONAL PERFORMANCE EQUATIONObservation of the feed and product size distributions going into and discharging from the mill in grinding circuits with low versus high circulating load ratios initially led to the definition of “Circuit Classification System Efficiency” (or CSE, McIvor, 1988a), and subsequently the discovery of the Functional Performance Equation (McIvor, 1988b; McIvor et al, 1992). The CSE is the fraction or percentage of “coarse” (usually in reference to the plus P80) size material inside the mill, versus “fines” or product size material finer than the circuit P80. It can be readily calculated by taking the average of the percentage of said coarse material in the mill feed and mill discharge streams. As this also represents the percentage of the mill energy expended on targeted, coarse size material, it is directly proportional to overall grinding circuit efficiency and production rate. This is all clearly expressed in the Functional Performance Equation for ball milling circuits, for which the derivation has often been presented (e.g. McIvor, 2006)."

Jan 1, 2011

By A. R. T. Denues

The Explosives Division of the Bureau of Mines, United States Department of the Interior, is investigating cushioned blasting at the Explosives Testing Station, Bruceton, Pa. The general interests of this investigation are practical and relate particularly to safety. The immediate concern is an application of cushioned blasting in coal mining In cushioned blasting, various means are employed to reduce the intensity of the application of energy in an explosive action in a borehole. The primary object is to increase the efficiency of the use of explosives.

Jan 1, 1940

By A. R. T. Denues

The Explosives Division of the Bureau of Mines, United States Department of the Interior, is investigating cushioned blasting at the Explosives Testing Station, Bruceton, Pa. The general interests of this investigation are practical and relate particularly to safety. The immediate concern is an application of cushioned blasting in coal mining. In cushioned blasting, various means are employed to reduce the intensity of the application of energy in an explosive action in a borehole. The primary object is to increase the efficiency of the use of explosives.

Jan 1, 1940

By J. M. Goris

The U.S. Bureau of Mines is conducting research on cable bolt ground supports to assess their material and support properties, to provide design criteria for using cable bolt supports as roof control systems under various types of underground mining conditions, and to provide a mathematical model of cable bolt support systems. Part 1 describes laboratory studies of the support properties of cable bolts made of conventional steel cables and provides recommendations on such topics as the use of thick grouts, selection of breather tubes, and reduction of water bleeding in cement-based grouts. The studies evaluated both single and double cables; effects of different embedment lengths, water-cement ratios, and grout curing temperatures on support strength; effects of use or nonuse of breather tubes; pumpability and water-bleeding properties of grouts; and the strength properties of sand-cement grouts. Part 2 will cover the strength characteristics of birdcage cable bolt supports, epoxy-coated cables, and cables with steel buttons attached.

Jan 1, 1990

By B. Radwanek-Bak

The assurance of future raw materials supply to the EU mineral industry has become, in recent years, one of the most important tasks of the EU Commission. It is focused on creation a new mineral policy within the EU zone. One of the starting points for this activity was identification of the mineral commodities that are critical for the sustainable development and technological progress. The paper presents the glance to this problem from the National Member level. Domestic mineral reserve base as a possible source of critical raw materials for the EU was shown. Poland cannot be considered as its resource base. The source of these raw materials are not only scarce in Poland, but also they are not produced, and their demand is now - and according to forecasts is going to be in the future - met by imports. The raw materials in question are not considered exactly critical for Polish economy, but they are of limited economic importance. On the other hand, their growth is a best opportunity and at once the need to the future sustainable development.

Jan 1, 2011