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By H. J. Handewith

This paper explores the state-of-the-art of mechanical rock drilling and boring methods in use in the year 2000. It covers the basic mechanisms of cutting tool design and outlines the current understanding of related rock fracture methods. It provides suggestions for future research needs and discusses the mining and construction markets that are driving these needs.

Jan 1, 2001

By D. S. Saxena, Jack K. Tuttle

Lack of understanding of useful applications of explosives on construction work stem primarily from the fact that explosion is commonly associated with destruction. On rock excavation and other construction works a certain quantity of explosive is harnessed to perform useful work at the source e.g. blasts to disintegrate rock. Development in rock blasting techniques, including the use of multiple-row blasting with short delay ignition, have made it impossible to excavate rocks close to or below buildings even in closely built-up areas. To permit the use of explosives on construction projects, in ways that will not damage existing structures, guidelines have been developed from careful measurements of intensity of ground vibrations. Accurate electronic instruments are now available for doing this. PLANNING AND CONTROL Blasting operations must be carefully planned and carried out to avoid discomfort to persons or damage to property. This increase in the use of rock blasting in city areas alone has led to a number of problems due to ground vibrations, air shock waves, and the psychological effect of noise. While the latter seldom if ever causes damage, it does create irritation and discomfort to persons living or working near the blasting sites. A result of this is a steady increase in the number of complaints in respect of damage to houses and other premises. Many such complaints are genuine and damage may undoubtedly be caused when incorrect blasting techniques are used.

Jan 1, 1997

By Daniel Journeaux

Introduction Daniel Journeaux is President of Janod Incorporated. Janod is a family owned and operated company that has been working in the field of slope stabilization since 1970. Daniel has worked in the rock stabilization industry for 25 years and has been President of Janod since 1992. Daniel has been an invited speaker for the Federal Highways Administration for the Northwest and Southwest divisions, Queens University in Kingston Ontario, The University of Laval, Vulcan Materials Company, CSX annual meeting for the Northeast Division. Daniel has written several articles and has been published in Pit and Quarry, World Tunneling, and American Shotcrete Association magazines. What is Required to Remediate Highwalls There are several techniques available to stabilize highwalls or temporary rock walls to allow for safe mining practices. The following are some of the techniques that can economically be used.

Jan 1, 2005

Membrane technology has been available for over 36 years, but has been used sparingly in the general mining industry. However, recent developments in polymer chemistry, spiral wound element construction, pretreatment equipment and techniques and an expanded understanding of membrane fouling and cleaning techniques have dramatically improved the reliability and robustness of membrane based systems in the mining industry. Harrison Western has expanded the use of this “new” technology to enhance the use of membrane technologies to separate metals from large volume heap leach mining solutions containing copper, zinc, and iron, gold or silver. Moreover, membrane technologies are ideally suited to fractionations that add value to processing fluids from refineries like separating metals from acids or concentrating acids and producing high quality process fluids. Finally, wastewater from Acid Mine Drainage (AMD) or, as in the case of the Newmont Yanacocha Mine in Peru, the treatment of excess barren leach solution created during the rainy season, can be cost effectively processed to meet World Bank Standards for surface discharge. Polymeric membranes, specifically thin-film composites, have been developed that will purify, fractionate or concentrate gold, silver, copper, zinc or nickel. Recent applications have been developed for spiral wound modules that operate across the pH spectrum from 0 to 14. Systems using membranes have been constructed that operate on feed streams from 140° C to 300 centipoise. Opportunities exist to apply membrane technology to concentrate gold, silver, copper, zinc or nickel using thin film composite membranes. Engineered membrane types can operate across the spectrum from low pH (<2) acid applications to high pH > 10 cyanide applications. Incorporating HW EMS™ membrane technologies into current mining operations could allow one to increase production because the membrane technology would be used to pre-concentrate heap leach solutions, and therefore, increase utilization of existing extraction and refinery capabilities.

Jan 1, 2007

By Maurice A. Ponti

The D.C. Water and Sewer Authority is implementing the Anacostia River Projects component of its Long-Term CSO Control Plan, including 21 kilometers of 3.7- to 7-meter-diameter CSO near-surface diversion storage/conveyance structures and flood relief, pressurized-face, soft ground tunnels at a maximum depth of 65 meters. This paper describes a project-specific soil grouping system that is primarily based on soil characteristics for tunneling derived from tests including Atterberg limits, grain size, swelling, mineralogy, triaxial, pressure meter, and consolidation, which differentiates the project from past area tunnel projects using descriptive systems based primarily on area geology.

By L. "Andy" Anderson, Stephen N. Short, James E. Friant

Since the introduction of "boxhole" drilling in South Africa in 1973, the concept of a blind raise, drilled upward from below, has become an accepted mining practice. A combination machine, capable of constructing raises to a mining level below, or blind raising upward from a single setup position adds a further dimension in versatility. A machine with these dual operating modes was designated by The Robbins Company as the 53R and was introduced into the Western Deep Level Mines, South Africa in 1984. The unit is powerful (200 hp) and compact (18,000 lbs., in a 10 ft x 4 ft 5 inch x 4 ft 6 inch package). This paper describes the design considerations for the new machine, provides field data from early trials, and looks briefly at its overall market and potential.

Jan 1, 1985

The inquiry into the explosion at the Moura No. 2 Mine in August 1994 recommended -?Emergency procedures should be exercised at each mine on a systematic basis, the minimum requirement being on an annual basis for each mine.? (Windridge et al. 1996). In December 1996 the ?Approved Standard for the Conduct of Emergency Procedures Exercises? was published and has been subsequently revised (Queensland Department of Mines and Energy Safety and Health Division 1999). This document provided guidelines for conducting mine site emergency exercises as well as the requirement for a test of state-wide emergency response by holding a Level 1 Mine Emergency Exercise at one mine on an annual basis. From 1998 to date (January 2008) ten Level 1 Mine Emergency Exercises have been held in Queensland, Australia. This paper discusses each of the exercises conducted to date as well as the logistics, scenario preparation, planning and organising required to conduct emergency exercises at this level.

Jan 1, 2009

By Alan Weakly

The Powder River Basin (PRB) of northeastern Wyoming and south-central Montana is the largest strippable reserve of compliant coal (0.6 or less lb of sulfur per million Btu) in the United States. In mining parlance, it is the Mother Lode! Wyoming’s portion of the Basin provides one fifth of the coal produced in the United States annually, and the state has been the nation’s top coal producer for the past six years. Based on 1993 production statistics and estimated strippable compliance coal reserves, Wyoming may remain the nation’s top producer for the next 76 plus years. Past articles on the PRB have focused mainly on production. After living and working in the Basin for the past five years, I have developed an appreciation for the area and its major industry that transcends size and production data. In the fall of 1993, MINING ENGINEERING’s publisher and I decided to present a series of articles that would cover many other aspects of the Basin. Ten topics were outlined, and specific individuals, selected for their knowledge and experience, were asked to contribute articles about their specialties. Although Montana has four large mines producing coal from the PRB, this series of articles will concentrate on the Wyoming portion of the Basin.

Jan 1, 1994

By Werner Burger

The Hallandsås project with a long history, first started in 1991, is well known in the tunneling community. In the past it has been stopped twice for technical and environmental reasons. The third attempt started in 2004 using a dual mode rock TBM. The heterogeneous highly fractured and abrasive rock mass as well as large areas of water bearing zones present most difficult subsurface conditions. The tunneling concept is based on the use of watertight segmental lining and a TBM able to operate in open mode, possibilities for extensive pre excavation grouting and high pressure closed mode operation up to 13 bar to cover exceptional conditions.

By Aldino Campos, Frederico Carvalho Dias, Pedro Madureira, Patrícia Conceição, José Gomes-Pereira, Inês Tojeira, Andreia Afonso, António Calado, Luísa Pinto Ribeiro

Since 2008, the Portuguese Task Group for the Extension of the Continental Shelf has been operating the ROV "Luso" (rated for 6000m depth) for geological sampling of the deep North Atlantic seabed, performing surveys on, e.g., seamounts and hydrothermal vent fields. Amongst other sensors, the ROV is equipped with a full HD video camera with which still images of the deep ocean floor are recorded. Fixed on the ROV’s frame are two underwater "line" lasers, each generating a sharp green line (532nm) over the seabed. The two lasers are paralleled and calibrated at a set distance. Provided that the camera’s angle of view is known, numerical values for seabed surface area may be calculated using direct measurements taken from the pictures containing the laser lines. We present the corresponding main mathematical formulas, which are derived from simple geometrical considerations, and discuss how to generalize these results for an arbitrary camera tilt or pan. We present an example of application of our method by estimating values for percent coverage of rock substrate versus sediment. Our results are also relevant for determining seabed polymetallic nodule abundances from still images obtained during ROV surveys.

Sep 1, 2014

By Peter Klaver

Deep tunnels have been used for decades for the temporary storage of large volumes of urban runoff, both storm water and combined sewer overflow (CSO). Tunnels are attractive because they reduce surface disruption and do double duty as storage and conveyance systems, collecting overflows from multiple locations and transporting them for treatment to various facilities. Like any hydraulic system, however, there are dynamic effects that must be fully understood during the design phase so that the final constructed product does not have unintended negative consequences. Preliminary sizing of storage tunnels is typically based on the total volume required. For example, if studies have determined that a volume of 56.8 ML (15 million gal) will provide the intended level of control, then that figure can be used, along with a preliminary idea of the desired tunnel length, to compute the required diameter. Of course, filling a long tube with water from various points along the way is not at all the same as pouring water into a bucket, and these dynamic effects require additional attention from design engineers. The rapid filling of storage tunnels can lead to the formation of bores, which are essentially moving walls of water. An open channel bore can build in height until it reaches the crown of the tunnel, at which point it becomes a pipe-filling bore. Figure 1 depicts both kinds of bores moving upwards in a rapidly filling tunnel. Bores can strike the ends of tun-nels with tremendous force, driving water and entrained air upwards into dropshafts and creating strong pressure surges in portions of the tunnel that are already filled. If the hydraulic surges are high enough to reach grade, they can cause overflows and/or damage structures at the surface. Trapped air pockets can occur through several phenomena, including the reflection of bores off dropshaft structures and the occurrence of ?premature pressurization.? The latter refers to the situation where the inflow to a tunnel is increasing more rapidly than the tunnel can convey it, such that the pipe becomes surcharged at an upstream point while points downstream are still flowing as an open channel. These air pockets are a great nuisance as they migrate toward points in the tunnel where they can rise to the surface, which are often shafts that are already filled with water (Fig. 2). The ?geyersing? that results can be hazardous and costly.

Jan 3, 2010

By Albert Adu-Acheampong

Fairmount Mineral&apos;s Maiden Rock underground sand mine historically delivered air to ventilate diesel-powered equipment at its working faces through high-resistance, 381-mm- (15-in.-) diameter PVC distribution lines. In support of plans for expanded production, three new, low-resistance ventilation design alternatives were analyzed. The study determined that adequate ventilation for expanded production was possible with various commercially available, high-volume/ low-pressure fans combined with a systematic layout of control structures. The recommended redesign was implemented in 2001, resulting in a significant increase in flow volumes and a noticeable improvement in the mine environment.

Jan 1, 2008

By S. Ersayin, I. Iwasaki

Application of a magnetic field was shown to be effective in controlling iron losses in pilot-scale cationic silica flotation in the processing of magnetic taconite concentrates. The design of a magnetic field distribution device and batch flotation test results using a 1.42m3 (50 cu. ft.) WEMCO cell are reported. Major losses of iron units in froth products were in the -25µm (500 mesh) fraction, and the application of a magnetic field decreased the flotation of fine magnetite, thereby improving the selectivity of separation. The “as received” sample was sufficiently magnetized and no further benefit was gained by magnetizing treatment. Selectivity was somewhat adversely affected by demagnetizing the sample, though its effect was minimal due to the magnetic field. The device is simple in construction, low cost and may be installed readily in existing equipment.

Jan 1, 2002

By Robert C. Pease

Siskon Gold has started gold production at the San Juan deposit in northern California. The mine is located about 27 km (17 miles) north of Nevada City, CA (Fig. 1). It is scheduled to be-come the largest underground gold mine in California. It is situated in the western foothills of the Sierra Nevada Mountains in the Mother Lode gold belt. The property consists of 8 km2 (2,000 acres) of patented land. It is situated in a topographically high area known as San Juan Ridge, which is 213 m (700 ft) above and between the Middle Yuba and South Yuba rivers. The elevation is between 790 and 914 m (2,600 and 3,000ft) above sea level. Annual precipitation averages 1,346mm (53 in.). Most of that falls between November and April.

Jan 1, 1996

By Brett Campbell

The San Vicente to 2nd Aqueduct Pipeline?Tunnel project is a raw water conveyance tunnel linking the San Vicente Reservoir (SVR) to the 2nd Aqueduct Pipeline via Rancho Penasquitos Pressure Control Facility (RPPCF). This 58,230 lf long tunnel will be 8.5? final ID, and has four points of construction access. The job is classified into 6 Reaches of tunnel, identified by the dominant geology within the reach. This paper will focus on Reach 3, specifically the measures necessary to drill and blast a 550 lineal foot section of granitic rock tunnel immediately in front of an open face digger shield.

Jan 1, 2008

By J. H. Zietsman

Ilmenite smelting furnaces must be operated with a freeze lining of frozen slag to protect sidewall refractories from chemical attack by liquid slag. The process has two main control objectives: Firstly the slag TiO2 content must be controlled according to specification, and secondly a safe freeze lining thickness must be maintained. This text only concerns itself with the second objective. Freeze lining thickness cannot be measured directly due to conditions inside the furnace. It is therefore inferred from signals of thermocouples installed into the furnace sidewall. These signals are used as the &apos;controlled variables&apos; in the freeze lining thickness control loop. The dynamic characteristics of these signals are the focus of this text. During this study a model of the process was constructed to study interactions between the slag bath and the freeze lining. This model was used to conduct simulation-type experiments to study the influence of various parameters (temperature, slag composition, ilmenite feed rate, reductant feed rate, power input, etc.) on the slag bath, freeze lining, metal bath, furnace wall and other parts of the process. In the case of the furnace wall, the modelling results were first plotted in the form of time-dependent isotherms. The dynamic thermal behavior of the furnace wall became evident from these results. To illustrate the dynamics of sidewall thermocouple signals, the results were also plotted as time lags between events occurring in the slag bath, and the time when a thermocouple registered a temperature change. The events studied included sudden changes in slag bath state (composition and temperature), changes in operating setpoints (ilmenite feed rate, reductant feed rate, power input), and operational errors (complete loss of reductant or of all feed). All of the result sets showed significant lags between occurrences in the slag bath and temperature changes in the refractory wall. The delays are such that it appears impractical to rely on sidewall thermocouple signals for warning of impending damage to the refractory wall, or for purposes of actively controlling freeze lining thickness. Some measures are suggested to improve the usefulness of these signals during furnace operation.

Jan 1, 2005

By R. Tamblyn

Vertically stirred media mills are a highly effective low-footprint solution for the ultrafine grinding of industrial minerals. This work investigates the effect of media density on flow patterns within the mill. Direct irradiation of a media particle leads to decay through positron emission, consequently forming two anti-parallel gamma rays, which allow for the real time tracking of particle position. Grinding media of the same size, but with a range of specific gravities are followed using this method, and the effect on the flow within the mill is revealed. The technique is seen to be an effective method to highlight the velocity profiles within the mill, as well as the zones where grinding is less efficient ? areas of relatively low velocity and high residence time. The changing media is seen to effect the overall flow patterns within the mill, having consequential effects on the efficiency of the grind.

Jan 1, 2009

By Roshan B. Bhappu

Integrating a research and development department into an engineering company&apos;s corporate structure can be rewarding to the engineering division, the R&D group, and, most of all, the company&apos;s clients. Actually, the R&D department is a logical extension of the conventional processing group within an engineering organization-but the R&D group provides services as needed to the engineering department while it is carrying out regular testing, pilot plant, and preliminary feasibility studies. Backup Services Provided With an R&D group, the engineering division does not need a process engineering group as such. The R&D group provides project backup services for feasibility studies, preliminary and detailed engineering, construction, and startup. The R&D group, in turn, benefits from its close association with project engineers, draftsmen, estimators, and computer capabilities in the engineering division. The client also benefits from the arrangement because R&D and engineering skills are available to both departments on an as-needed basis without standby eost. To handle the integrated responsibility of R&D projects, as well as conceptual design and preliminary feasibility studies, the R&D staff must be carefully selected. These research engineers should: • have a good background in plant practice as a mill superintendent or chief metallurgist; • be capable of organizing and supervising a testing program or a pilot plant campaign; •be innovative and willing to accept new ideas and concepts; • be able to translate lab test results into a workable flowsheet through sound conceptual design and feasibility studies; and •be able to communicate with clients. In short, the R&D engineer must be a jack of all process-engineering trades to successfully take a project from concept to operating reality. Engineers in a metallurgical R&D organization should have experience in mining and processing all types of

Jan 10, 1980

By A. Arik

An accurate estimation of mining block grades continues to be a challenging task for ore reserve practitioners. Two of the factors that affect the accuracy of the estimates are the estimation method used and the variability of the mineralization in the deposit. The objectives of the study are twofold: Firstly, to see how different estimation methods perform on a given deposit. Secondly, to determine the impact of particular nature of the mineralization on the results. The comparison of several estimation methods for the prediction accuracy is performed using the conditional simulation results as the basis.

Jan 1, 2000

By G. J. Joy

Although rates of pneumoconiosis in coal miners have declined substantially in the United States since the passage of the Federal Coal Mine Health and Safety Act of 1969, new cases continue to occur, including cases of rapidly progressive disease. In contrast, Australia?s underground coal mining industry has reported few new cases of pneumoconiosis for over twenty years. Mortality from Coal Workers? Pneumoconiosis in official health statistics and the prevalence of pneumoconiosis among miners screened in x-ray surveillance programs are also lower in Australia. To understand this disparity, the National Institute for Occupational Safety and Health was requested by both industry and labor stakeholders to examine this issue, with the ultimate aim of reducing the rate of pneumoconiosis among United States coal miners. A number of factors, including coal dust exposure, silica exposure, and coal rank were examined as potential contributors to the above observed differences. Comparison of coal rank data from each country did not show any significant differences. Air sample data from the coal mining industries in both countries show that coal dust levels in Australian mines are somewhat higher than those reported in similar U.S. mines; however, quartz exposure for Australian miners is lower than for many U.S. miners. Assuming that quartz is contributing to the greater number of cases of advanced pneumoconiosis in the U.S., more effective dust control measures, as well an independent exposure standard for respirable quartz in coal mining, need to be implemented to prevent this potentially disabling condition.

Jan 1, 2011