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By R. H. Thompson

Preliminary safe distances for blasting wiring from typical electromagnetic sources are presented. The distances are for underground coal mines and electromagnetic sources in the frequency range below 10 MHz. The distances are based on measurements performed at 3 locations in each of 3 coal mines. The measurement apparatus, measurement procedure, measurement results and the rationale used in the calculation of the safe distances are all described. The safe distances presented are dependent on the measurement results and their interpretation. More measurements are clearly necessary to establish the validity of the suggested distances.

Jan 1, 1985

By Donna L. Anderson

The first section of this U.S. Bureau of Mines report includes a discussion of the navigational tasks performed by operators of mobile mining equipment, with the focus on the navigational information and guidance techniques required by continuous mining machine operators. Some previous research and attempts in remote and autonomous navigation of continuous mining machines are mentioned. Issues of research in autonomous navigation of various other mobile robots are presented, with attention focused on their applicability to a continuous mining machine navigating in the mining environment. Conclusions are stated on methods of automating the navigational tasks of a continuous mining machine, and a decision to concentrate initial attempts on the tasks of autonomous face navigation is defended. The second section of this report includes a presentation of the Bureau's proposed solution for autonomous face navigation of a continuous mining machine, which includes the employment of a mobile roof support as a reference for guidance in the face area, and a navigational guidance system for the continuous mining machine.

Jan 1, 1989

By Harry Siewert

"The commissioning of the 4th concentrator (C4) at Freeport Indonesia in early 1998 increased total mill throughput from 130k to 230k tonnes per day. The C4 flowsheet consists of a single 38 ft diameter SAG mill, four 24 ft diameter ball mills followed by four banks of 4,500 ft3 WEMCO flotation cells.The design of the C4 rougher flotation circuit was based on the expectation that the copper and gold recoveries achieved with the 4500 ft3 flotation cells would be equivalent to or better than that achieved with the 3,000 ft3 flotation cells in the 3rd concentrator (C3) rougher circuit. This assumption was due to the fact that the C4 flotation feed size would be less than 15% +212 microns compared to the C3 rougher flotation feed size of less than 23% +212 microns. By mid 1998 it had become apparent that the C4 rougher flotation copper and gold recoveries were below those predicted.In order to determine the cause of the lower recoveries, stage by stage rougher flotation surveys were performed in all four concentrators. The results of the surveys showed that the C4 rougher flotation circuit had a lower recovery of +200 micron material than that achieved in the C 1, C2 and C3 concentrators. Through mineralogical analysis, it was determined that a majority of the copper contained in the +200 micron fractions was liberated and recoverable. This paper describes the steps taken to increase coarse particle recovery, overall plant recovery and the results achieved."

Jan 1, 2001

By Andy Schroeder

Located in Hamilton, Ontario Canada, Berminghammer Foundation Equipment, is a manufacturer of advanced foundation equipment with 30 years of experience. The company is represented in more than 20 countries world wide, maintains an extensive Research and Development team, and has earned a reputation for finding the most practical solutions to the most challenging projects. The vertical travel lead, referred to as "VTL" system, was first developed and patented by C.W. Bermingham in the 1970's. This lead system was developed in response to the fundamental limitations of either a fixed lead or hanging lead system. The fixed lead system is well suited to level job sites with few obstructions and has the advantage of faster positioning of the lead, the hanging lead is very adaptable to different elevations and batter piles but takes much longer to position. Therefore the Vertical Travel Lead was developed to combine the advantages of fixed leads, fast and accurate positioning, with the ability to adjust the height of the lead base up or down. The VTL lead is connected to the boom by a sliding connection which allows the lead to be elevated or lowered below grade. The advantages of the VTL system were recognized by many foundation specialists and they have become the Industry standard in Canada , US Railway Construction , and many parts of the USA.

Jan 1, 1997

The Golden Cross mine commenced production in December 1991. Both open pit and underground mines produce 1000 tonnes of ore per day. Mining techniques are discussed along with results and variations to proposed methods of extracting the ore.

Jan 1, 1992

By Michael J. Beus

This Bureau of Mines report describes a field experiment involving the sinking of two test shafts to directly compare the deformational behavior of circular and rectangular shapes. Results show that the circular shape is less sensitive to geologic discontinuities and applied stress field. Also, the rectangular shape is subject to a variety of behavioral modes, including beam bending and buckling. Geologic discontinuities around circular and rectangular shapes influence displacement significantly. Simple, two-dimensional elastic finite-element modeling, simulating circular and rectangular shapes in a biaxial stress field, shows that the structural response of a shaft is largely controlled by geologic structure. Consideration of anisotropy may be required for realistic analysis of a deep shaft.

Jan 1, 1985

By Benoit Bissonnette

"The need for production of a competent fill was recognized early by the project partners. Consequently, a 4000 Ud paste fill plant was constructed and commissioned in early August 1994.In order to fine tune the process without risk to the underground workings, a closed pumping loop was devised on surface. After two months of this exercise, the first underground slope was filled according to specifications obtained from the pilot plant trials.This paper will focus on the operational problems encountered and the solutions adopted so far, and on a comparison between expected and actual fill production and characteristics.RésuméLa nécessité de produire un remblai de propriétés mécaniques suffisantes a été rapidement reconnue par les partenaires du projet. Conséquemment, une usine de production de remblai en pate, utilisant les residus du concentrateur d'une capacité de 4000 t/j a été construite et l'opération a débuté au mois d'aôut 1994.Dans le but de roder le précedé sans mettre en danger les installations souterraines, l'usine a été testée dans un circuit de surface. Après deux mois d'essais, le premier chantier souterrain a été rempli avec du remblai en pate selon les specifications dérivées de l'usinage pilote.Cet article présente les problemes d'opération rencontrés et leurs solutions, en plus de faire une comparaison entre les résultats prévus et ceux actuellement obtenus sur la production et sur les charactéristiques du remblai."

Jan 1, 1996

By J. H. Adkins

The goal of this program was to produce a set of baseline health and safety training materials that could be used by the metal/nonmetal mining industry to reduce injuries and to comply with federal training requirements. The materials developed are arranged in a two level outline format. The first level provides the title, course goals, background and topical outline while the second level provides a detailed outline of the course content. Visuals, designed to portray miners in a positive, attractive fashion, were done in simple line drawing so they would reproduce for handouts without loss of quality. Each of the required units in the Baseline Guides have one or more self-checks. These are designed to be suggestive of evaluation techniques the users can develop for themselves. An instructors guide and a mining terms glossary are included. In a second phase the program developed performance based training guides for Annual Retraining and Experienced New Hires in the Underground Salt Industry.

Jan 1, 1983

By David R. Morrey

During the past 50 years, significant research has been performed in the ecology and physiology of plants that colonize soils containing elevated concentrations of heavy metals. Similar work has also been performed on plants that are able to survive acidic and saline environments. Efforts have focused on the ecological analysis of plant communities that occur over a range of metalliferous mining wastes. Investigations have been performed on the mechanisms that allow selected varieties of plant species to survive in normally phytotoxic environments and on the potential applications of metal-tolerant varieties of plant species. The purpose is the remediation and reclamation of mining wastes and soils that contain unusually high concentrations of so-called heavy metals. Characteristics of some mineral wastes Metalliferous mining wastes present special environmental restoration problems because of their toxicity. Potential toxicities are mostly caused by residual metals derived from weathering of low-grade ore or the waste products of mineral processing. In cases where pyrite forms a part of the mining waste, acid generation by oxidation may exacerbate the toxicity problem by promoting heavy-metal mobilization in aqueous solution.

Jan 1, 1995

By M. Dattilo

The U.S. Bureau of Mines has been conducting research on the use of waste-derived zinc as a partial replacement for pure zinc in the electrogalvanizing process. The end product of this process is automotive sheet, which has enhanced cosmetic protection over previously used cold-rolled (CR) steel. In this study, primer-coated specimens of CR and electrogalvanized (EG) steel were subjected to the on-vehicle environment and monitored periodically by electrochemical impedance spectroscopy (EIS) during immersion in 1M NaCI solution. The results of these tests were compared with immersion-only conditions. Scanning electron microscope (SEM) and energy-dispersive X-ray (EDX) techniques were also used to evaluate the corrosion processes and compare them with atmospheric exposure specimens. EIS was found to measure the corrosion associated with on-vehicle exposure, thus providing an excellent screening technique for evaluation of the performance of EG automotive sheet steel.

Jan 1, 1990

By D. A. Bruce

The paper describes the construction of 5 plugs to resist high water heads at depth within the South Deep Gold Mine, Randfontein, South Africa. A total of 20 segments were involved to create these plugs, which were 7.5 m long at the 58 Level and 6.25 m long at the50 Level. Emphasis is placed on the QA/QC and verification methods, which were developed and governed all phases of the work, from initial rock preparation and pregrouting through to the final grout tightening of the rock/plug interface and the surrounding rock. This paper is one in a series of papers detailing other aspects of the project, which was constructed largely between May 2001 and August 2003.

Jan 1, 2006

By John A. Breslin

The Bureau of Mines measured respirable dust in coal mines by means of multiple dust samplers worn by persons moving about the mines. The measurements were made primarily to evaluate the effectiveness of certain dust-control techniques; however, for this report, the data have been analyzed to determine the precision of the personal dust-sampling measurements. A total of 68 sets of measurements were available from multiple personal samplers. The measured dust masses were less than 1.0 mg because the sampling times were short. The coefficient of variation calculated from these data was 18.5 pct, compared with coefficients of variation ranging from about 10 to 30 pct, which were calculated from the most precise and extensive data available for fixed-point dust measurements made in coal mines. From this comparison, it is concluded that dust samplers worn by personnel are as precise as fixed-point samplers in measuring respirabe coal dust; the wearing of the samplers by someone moving about a mine does not contribute significantly to the variation in measurements made with these instruments.

Jan 1, 1983

By Ian Martin

A precious metals refinery’s switch to personal computer-based, three-dimensional piping design saved many hours in the design of a South African precious metals refinery. Bateman Minerals and Industrial provided engineering, procurement and construction management services for Impala Platinum Limited-Refineries’ new $60 million refinery in Springs, South Africa. This project is one of the largest platinum refineries in the world. Bateman evaluated a new design method during this project that involved developing a three-dimensional model for the project. The new method saved time by reducing the man-hours required to generate complete project documentation, including plans, sections, isometrics and material takeoffs. The new method also saved design and construction time by allowing designers to detect clashes before construction began.

Jan 1, 2000

An underground mine disaster is an accident of major proportions that takes a significant toll in human lives. A disaster usually disrupts the normal functioning of a mine and may result in entrapment of miners whose normal egress from the mine is cut off. A disaster often necessitates a rescue operation and a means of keeping the trapped miners alive while they await rescue. Explosion, fire, inundation of water or toxic gases, and collapse of a major portion of a mine are among the causes of mine disasters. Miners threatened by such an occurence must either bring the situation under control (e.g., by extinguishing a fire) or remove themselves from the danger. If control is unsuccessful, they must retreat to a place of safety. Four different activities may be involved: evacuation, escape, survival, and rescue. Evacuation is the orderly exit of people from the mine using previously identified escapeways and following a previously determined evacuation plan. Miners whose normal evacuation routes are blocked may be able to find alternative exit routes and escape by their own efforts. For those who cannot, the issue becomes survival while waiting to be rescued. The survival period may last for many days while rescue efforts are mounted from outside the mine.

Jan 1, 1981

By W. L. Dare

Tri-axial strains in pillars, created by pillar robbing, were measured in an experiment at the Dysart No. 1 uranium mine near Grants) New Mexico. At this mine, room-and-pillar stoping is used on the advance, and pillars are recovered on the retreat. The are deposit is, for all practical purposes, horizontal. Measuring devices were installed in pillars approximately 90 to 200 feet from the break line, and strains were recorded over a 4-to 6-week period. The measurements indicate that, in general, the algebraic magnitude of vertical strains increased, and the horizontal strains decreased, in turn, indicating that vertical (or near vertical) loads on the instrumented pillars lessened as pillars were recovered.

Jan 1, 1962

By S. Bhattacharyya

"Coal bearing rocks are low in strength and have geological discontinuities and moisture sensitivity. Roof and rib falls have been a major cause of fatalities in underground coal mines. Mine engineers design ground control plans for regulatory approvals. A number of tools are available from the National Institute for Occupational Safety and Health to design and assess these plans. Quite often there is not enough geotechnical input information available and databases are used. The Appalachian coalfields have extensive scientific studies to provide reliable regional inputs. Coal mines in the western United States and Canada have different geological and geotechnical conditions, and less available data. Use of inappropriate inputs in the tools like Analysis of Retreat Mining Pillar Stability, Analysis of Longwall Pillar Stability, and Analysis of Roof Bolt Systems may result in unsafe designs or over conservative designs. The tools are convenient but thorough understanding of the inputs, calibration with local test results, and operating experience are important for effective designs. The current paper contains examples of difficulties faced during mine planning using the above tools. INTRODUCTION Sedimentary rocks hosting coal are low in strength. Scientific studies have placed the uniaxial compressive strength (UCS), triaxial strength, tensile strength, and shear strength of sandstone, shale, siltstone, and claystone in lower range of strength among engineering materials (1). Coal bearing rocks are most often weakened by the presence of faults, folds, slickensides, bedding planes, fractures, and other geological discontinuities. The host rocks and coal are often moisture sensitive. The geological discontinuities allow water to enter the strata from surface and underground sources. This combination of low strength, structural weakness, and presence of water results in difficult ground control situations for the coal mines. Roof (2) and rib falls have been a major cause of fatalities in the U.S. coal mines. Modern underground coal mines necessitate wide entries to accommodate large production equipment. The gate roads, section entries, and the mains entries of a highly productive coal mine are as wide as twenty feet (6.1 m). The actual intersection width is nearly thirty feet (9.1 m). Adequate ground control is a key to maintain safe production in such mines. Mine engineers and their consultants routinely submit ground control plans to the regulatory authorities. While working out the necessary roof control system the mine engineers are required to demonstrate the adequacy of the proposed system. There are multiple ways to demonstrate this. Some engineers use traditional load calculation approach of roof bolts (3). Some engineers use numerical methods. Yet a large number of professionals resort to a suite of ground control design software offered by National Institute for Occupational Safety and Health (NIOSH) commonly referred to as “NIOSH Ground Control Toolbar.” These software tools are free and easy to download from NIOSH website. The software included in this package are: Analysis of Longwall Pillar Stability (ALPS), Analysis of Retreat Mining Pillar Stability (ARMPS), Coal Mine Roof Rating (CMRR), Analysis of Roof Bolt Systems (ARBS), Analysis of Horizontal Stress Effects in Mining (AHSM), Analysis of Multiple Seam Stability (AMSS), Analysis of Retreat Mining Pillar Stability - Highwall Mining (ARMPS-HWM). These tools are relatively simple to install and use in planning and designing coal mines and prospective coal mines. They accept a number of geotechnical inputs which are collected from either an existing mining operation or from exploratory boreholes. In the absence of necessary input parameters, the programs use default values which are drawn from databases of geotechnical properties built by NIOSH."

Jan 1, 2015

By Jonathan Ludlow

This document is the final report of a study aimed at defining the relative contributions of various sources of respirable airborne dust on longwall faces. In order to define the contribution of various primary sources, continuous dust level data were recorded on five longwalls for an average of five shifts at each. By analysis of these data with records of face activity, it was possible to determine the overall contribution of each of the major elements of the longwall system to overall respirable dust exposure at various face locations. Average levels were determined for roof support generated dust, conveyor and intake dust and for dust levels during various shearer activities. When average levels are compared between mines, a significant degree of consistency is noted. The next phase of the study was aimed at differentiating the various dust sources associated with the shearer. To this end 'fly cuts' varying from 6 in. to 30 in. were closely monitored as were dust levels at operators' positions over the various segments of longwall cycle. These data indicated that the clearance ring of the shearer drum as a disproportionately heavy contributor to shearer dust make. A statistical analysis of the effect of shearer haulage speed on dust make revealed that high haulage speeds are associated with low specific dust make.

Jan 1, 1983

By P. N. Erasmus, M. Heyns, M. J. Pretorius

The characteristic of stope supports plays a vital role in the design of the supports. This paper deals with the characterisation of both cellular lightweight concrete and timber supports since both supports absorb and dissipate the energy in different ways. The behaviour of the support and hence its performance is simulated for different loading conditions by constructing a model consisting of various mechanical components like springs, dampers and blow-off valves. When the force exerted by the stope support increases significantly during deformation of the support, the stresses in the hangingwall could exceed values where failure of the hangingwall may occur. There is a need to understand this phenomena and the work presented in this paper is a first attempt to start with the characterisation of the stope support. Les caractéristiques des supports de taille jouent un rôle vital dans la conception des supports. L’étude présente traite de la caractérisation des supports cellulaires en béton léger et en bois, puisque ces deux types absorbent et dissipent l’énergie de façons différentes. Le comportement du support et par conséquent sa performance est simulée pour des conditions différentes de chargement en construisant un modèle qui consiste en des organes mécaniques variés tels que ressorts, registres et valves d’échappement. Quand la force exercée par le support de taille augmente considérablement pendant la déformation du support, les contraintes dans le toit peuvent dépasser des valeurs qui pourraient entraîner la défaillance du toit. Il est nécessaire de comprendre ce phénomène et l’étude ici présentée constitue un premier essai dans la caractérisation du support de taille. Die Charakteristika der Strossenunterstützung spielt im Design von Unterstützungen eine vitale Rolle. Diese Arbeit befaßt sich mit der Charaketerisierung sowohl der porösen Leichtgewichtbeton- als auch mit der Holzunterstützung, da beide Unterstützungen Energien auf verschiedene Art und Weise absorbieren und auflösen. Das Verhalten der Unterstützung und folglich seine Leistung wird für unterschiedliche Ladezustände simuliert, indem ein Model konstruiert wird, welches verschiedene mechanische Komponenten wie Federn, Dämpfer und Ausblaseventile enthält. Wenn die von Strossenunterstützung während einer Unterstützungsdeformation aufgebotene Kraft signifikant ansteigt, könnten die Spannungen im Bereiche des Stollenfirstes Werte überschreiten wo ein Versagen des Stollenfirstes eintreten kann. Es besteht die Notwendigkeit dieses Phänomen zu verstehen, und die Arbeit, die in diesem Elaborat dargestellt wird, ist ein erster Versuch, mit der Charaketerisierung der Strossenunterstützung zu beginnen.

Jan 1, 2003

By A. C. Johnson

This circular is one of a series published by the Bureau of Mines describing mining and beneficiation methods and costs at various mining operations throughout the United States. Inclusion of the Abbott mine in this series is of particular interest, as the complex geology and the character of the deposits make their exploitation a unique operation. The mine operates on a high-cost, comparatively small-scale basis, and only the persistence of an aggressive management has enabled it to maintain its rank among the major mercury producers of California. Rising costs and decreasing metal prices, which continuously threaten the low profit margin, are reflected in increased efficiency of operation. This report summarizes past operations and describes, in detail, the geology and ore deposits; exploration and mining methods; and furnacing and condensing operations. It covers the entire operation from initial exploration to the actual production of mercury. Comparative production costs for 1944 and 1958 are of special interest.

Jan 1, 1962

By M Rafty, A Markham, S Atkinson, M Heyting

Over recent years there has been a significant increase in the number of miners in the Pilbara region of Western Australia targeting channel iron deposits (CID) located in valleys, intersected by ephemeral creeks and below the groundwater table. The falling iron ore price has triggered a drive to reduce cost and maximise yield. Creek diversions provide an opportunity to maximise the utilisation of orebodies and extend the life-of-mine.Creek diversions that are required during mining operations to access ore and provide flood protection have historically been constructed as uniform engineered channels designed primarily for flow conveyance while minimising earthworks costs; however, the design of diversions becomes more complex when they are required to function in a similar way to the existing creek system during operations and remain stable during more extreme events than would typically occur following mine closure, in accordance with current regulatory guidance. The design specifications for closure are often more rigorous than the operational phase, and could incur significant additional cost to implement retrospectively if not planned and designed upfront.The complexity of diversion design depends on site specific factors such as: the size of the creek to be diverted; hydrology; corridor restrictions; geomorphology; hydrogeology; geology; environmental and heritage values; potential impacts and the risk to operations and environment. The complex interactions of these factors must be well understood and hydraulic modelling undertaken to characterise the existing creek system, demonstrate the diversions, provide adequate flood protection during operations, and can function in a similar way to the existing system following mine closure. This paper presents key design considerations for Pilbara creek diversions, operational and closure requirements, mine planning considerations, risks, cost saving opportunities, and the benefits of an integrated approach to design.CITATION:S Atkinson, A Markham, M Rafty and M Heyting, 2017. ‘Back to the future’ – resilience in historical context and implications for the future, in Proceedings Iron Ore 2017, pp 367–374 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017