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By David R. Crouthamel, Francis L. Fong, Troy L. Page

This paper focuses on the results and the performance of the grouting program as a means to control groundwater infiltration during the excavation of the 7.7 km (25,160 lf.), 3.5m (11 ft. - 7 in.) diameter Inter-Island Tunnel beneath Boston Harbor in Massachusetts. Two major operations of grouting were performed - water cutoff grouting behind the tunnel heading after excavation and face grouting ahead of the Tunnel Boring Machine (TBM) operation. An array of products from cementitious to chemical grouts and various grouting procedures and equipment were employed to evaluate their effectiveness in controlling the water in-flows. Evaluation of the overall performance of each of the grouting rations, overall costs and comparison of face grouting versus post excavation grouting is made.

Jan 1, 1997

By R. S. Shepard

The closing remarks of a paper which I presented at the annual AIME meeting at Dallas, Texas during February of 1963; contained a forecast of increased activity in trackless underground ore mining which finalized that presentation. At that time, HAD I been peering through my brightest rose colored glasses, I could not have foreseen the unprecedented rapidity of acceleration of underground ore mining methods which has since ensued. From Death Valley, California diagonally to St. Johns, New Foundland; from Australia to Africa to Sweden to France and Germany; from South America to Southern Mexico to Northern Saskatchewan and Northern Manitoba the expansion of trackless underground ore mining methods has probably progressed at a faster rate than any other revolutionary' change in the history of underground ore mining.

Jan 1, 1967

By W. C. Lacy

Traditionally Australia has been a leader in underground mining methods with world standards being established at Mount Isa, Broken Hill, Kalgoorlie, and Mount Lyell. With decline in higher-grade reserves and discovery of a multitude of near-surface oxide gold de-posits attention has shifted to bulk mining of low-grade gold ores by open pit methods, heap leaching and activated carbon recovery of gold values. The paper examines historical change in mining philosophy and the economic effects of isolation.

Jan 1, 1993

By Dirk van Zyl

Natural materials can be used successfully in the construction of heap leach pads. The use of these materials usually result in the least expensive approach for such facilities. Sufficient geotechnical experience has been gained in the design and construction of clay heap leach pads so that they can be used with confidence. A number of operators presently use clay pads in their heap leach facilities; these include Alligator Ridge, Ely, Nevada (gold), and Union Carbide, Gas Hills, Wyoming (uranium). This paper describes the construction and field investigation of a clay pad for the heap leaching of agglomerated precious tailings. The project is located in the Mojave Desert, Southern California. The design had to satisfy operational requirements as well as regulatory requirements. The California Water Quality Control Board (WQCB) was one of the agencies which had to issue a permit for the project. Their biggest concern was the discharge or escape of cyanide into the environment. Rather stringent requirements were therefore placed on the pad design criteria, especially in terms of permeability.

Jan 1, 1983

By R. V. Ramani, R. A. Jankowski, R. Bhaskar

The spatial distribution of airborne dusts, deposition of dust in the airway, as well as the effect of airflow velocity and particle density on dust behavior in mine airways were studied in a set of experiments performed in a mine airway under controlled conditions. Considerable deposition of dust near the source was indicated. Pronounced effects due to velocity were observed in ambient dust concentration and deposition along the mine airway, both in the respirable and the total size ranges. Cross-sectional concentration measurements indicate an increase in concentration from the roof to the floor. The average cross-sectional concentration is about 75% of the concentration in the center of the airway.

Jan 1, 1987

By Paul D. Chamberlin

The evolution of heap and dump leaching has followed the development of agglomeration, materials of construction for leach pads and ponds, solution distribution systems, testing techniques, and state regulations. They are now mature processes. Possible future directions and developments are discussed. In situ leaching of precious metals is waiting to be commercialized. Regulators are reluctant to allow the use of cyanide because of the potential for excursions and operators are reluctant because of the potential for lawsuits. Developments in alternative lixiviants are needed before in situ leaching is accepted.

Jan 1, 1989

Computer programs commonly used to simulate mining operations generally require a fair amount of data. The common data input methods have been by either creating an ASCII data file or answering numerous questions during the data input phase. Both methods of data entry are tedious, time consuming, and inflexible. A screen handling system has been developed to drive FORTRAN-77 application software for the MS-DOS environment. The system utilizes keyboard functions with an aid of extended ANSI codes. It also allows a multi-view input data entries.

Jan 1, 1990

By William G. Kegel

Apart from a usable product and good 'mining conditions, the greatest asset for a profitable coal mining organization is an effective mine maintenance program. The first step in achieving this is to have good mechanics-or men who want to be mechanics and are interested in knowing more about the design and control of the machines in their charge. A good mechanic's knowledge and ability result from ambition, curiosity, and determination. Starting with these qualities, the aspiring mechanic can launch his career by learning all he can about mechanics, electricity, and hydraulics. Though the path is rough, the end result is rewarding. Mining machinery probably receives as much, if not more, abuse as any other heavy equipment in use today. Considering the conditions under which much of the repair work must be done, it is essential that the mine operator has the best men and tools to perform the work. Mining machines, from their inception, have utilized the electric motor; and down through the years of mechanization, this power source has undergone many changes to better adapt it to the job. The first motors used were direct-current (d-c) motors since d-c power was the most economical power source for mining at the time of early mechanization. These motors were large open-type machines which are seldom used in modern mining. Because of the mine environment, the d-c motor has been reduced in size to better suit the application in mining machines and is now manufactured with dust-tight or explosion-proof enclosures. The d-c motor is constructed with either (or both) series and shunt fields located on the stationary part of the motor (stator) and- an armature coil wound on the rotating part of the motor (rotor). Power is supplied to the armature by brushes which are held stationary and make sliding contact with the armature. The brushes requires regular and careful maintenance because worn or defective brushes will cause heat or arcing which can destroy the motor. D-c motors can be used as d-c generators when mechanical power is supplied to them by the rotating shaft. In the case of a locomotive, this principle is used in dynamic braking. The momentum of the locomotive drives the motor and generates d-c power. The power is regulated with resistors and provides opposition to the motion of the locomotive.

Jan 1, 1981

By K. C. Nathsarma

An attempt was made to extract niobium oxide from ~98.5% Nb2O5 using solvent extraction processes. Nb2O5 is used as the feed material in carbothermic reduction processes aimed at producing high-homogeneity, super-conductor-grade niobium on a laboratory scale. The Nb metal used for superconductor applications requires a residual resistivity ratio (RRR) > 300, which in turn needs a stringent purity of Nb and allows impurities (substitutional and interstitial) in ppm levels only. In this paper, solvent extraction of niobium was studied under various experimental conditions, such as effect of different extractants, concentration of methyl isobutyl ketone (MIBK) in the organic phase and concentration of various acids. The concentrate was digested with hydrofluoric acid, with ammonium fluoride (NH4F) as a stripping agent. The extraction of niobium from low hydrofluoric- (HF-) bearing solution was found to be low. Thus, various concentrations of hydrofluoric acid and sulfuric acid, as well as hydrofluoric acid and hydrochloric acid, were investigated towards obtaining a maximum amount of niobium in the filtrate and a minimum amount of niobium in the residue. A McCabe - Thiele plot for extraction of niobium from the aqueous phase, HF-bearing solution using HCl with 85% MIBK in kerosene has been constructed to determine the O:A ratio and the number of stages of the process.

Jan 1, 2011

By Don Suttie, Frank Roybal, John Wright

The Roybal Raise incorporates the simplicity and low cost of a short bald-headed raise while overcoming the usual impediments to driving a high baldheaded raise. The concept provides for speedy excavation and maximizing the use of the excavated opening, using the rock for structural support. The design is simple: two baldheaded raises are driven parallel to one another, interconnected by dogholes about 8 m (25 ft) apart. In this fashion, the raise can be driven safely and efficiently to 60 m (200 ft) or more. When the raise is complete, the excavation requires no timber for support or partitioning. Rather, the rock itself supports the construction. As a test, a two-compartment Roybal Raise was attempted at the Independence mine in the Willow Creek District of Alaska. One side was driven 2 x 2 m (6 x 6 ft), intended for a manway and equipment skip. The other was driven 1.5 x 1.5 m (5 x 5 ft) for a muck compartment. Both sides were driven at a 65° angle from horizontal and 1 x 1 m (4 x 4 ft) dogholes spanned the 4.6-m (15-ft) pillar between the two compartments. After topping out at 50 m (160 ft), the raise was found to meet all expectations of efficiency, low cost, and practical simplicity. Technique Preparing the Roybal Raise for driving involves no elaborate or costly site prep except assembling materials and providing for muck removal. Normally, the raise muck falls directly onto the sill or track and is picked up either by an overshot mucker or a front-end loader. Raise mining proceeds initially by taking up both compartments simultaneously to the first doghole. It progresses by alternating one side as a clear manway for access with the other side, the active side, as a muck compartment (Fig. 1A). This stage proceeds quickly for no mucking or staging is required to cycle the first three rounds. On the fifth round, in addition to the normal raise round, rib holes are winged out toward the adjacent raise, thus starting the dogholes. Finally, as the sixth raise rounds are drilled and shot, the first doghole is also completed from both sides. The second stage commences by establishing one side as a clear manway for access while the other side, used as a muck compartment, is prepared for active mining. Figure 1B illustrates this step in the succession of raising with the active side advancing to the second doghole level. During this stage, services are maintained through the manway side and equipment is stowed in the doghole during blasting. As the active side advances, muck may be allowed to fill the bottom portion of that side since it is unnecessary to clear it for access. The next stage of raising involves cleaning out the former muck compartment and preparing it for use as a manway. At the same time, the former manway is prepared for advance and use as a muck compartment (Fig. 1C). As in the previous step, the same doghole is used for access and equipment storage. The active side advances until the second doghole is completed, at which point equipment and access are moved to the new doghole. From there, the active side is driven past the second doghole 8 m (25 ft) more to the third doghole level. Again, half of the doghole and the next raise round are mined. The fourth stage involves switch ing back the manway side for the muck side (Fig. ID). The new muck side is driven to the third doghole where equipment storage and access are reestablished. From there, the active side is advanced to the fourth doghole. In the same fashion, the raise is advanced to the top, alternating the manway side with the active side, maintaining access through the inactive manway, and storing equipment in the uppermost doghole. The cycle time for driving each compartment, regardless of the raise height, is greatly improved over that for normal bald-headed raises of comparable height. By storing equipment in the upper-

Jan 1, 1984

By A. B. Holland-Batt

Following a relatively static period in the 1960s and 1970s when incremental development rather than innovation was the norm for gravity separation, the last 15 years has seen a number of new developments in this area. The paper briefly reviews the traditional gravity separation techniques and then examines the newer developments such as centrifugal separators. Particular emphasis has been placed on novel devices or improvements that offer either better control or improved performance.

Jan 1, 1998

By Reid Trent, Jon C. Volkwein

The U.S. Bureau of Mines is investigating a novel technique to control methane in underground mines by using methane oxidizing microorganisms termed methanotrophs. Coalbed methane has been responsible for many mine disasters and will continue to be a safety obstacle to mining deeper coal seams. Deeper seams of coal contain more methane gas, and better strategies for removing the methane will need to be developed. Methanotrophic microorganisms offer a novel alternative since they physically remove the methane, are commonly found in soils, and already have been found to exist in many foreign coal mines. Proposed applications of this concept include the inertization of buffer zones separating active mining areas from sealed gobs, reducing ventilation from ventilated gobs and reducing methane content from longwall gobs. Current work includes an assessment of the abundance of naturally occurring methanotrophs in U.S. mines, testing the amount of methane that various types of microorganisms can consume, studying the effects or use of the byproduct gases, and finally developing practical appl ications of this biotechnology to coal mining. This paper reports on the initial laboratory testing that measured the quantity of methane consumed by two types of methanotrophic microorganisms. Average rates of methane consumption were between 1 and 4 ml/hour in column flow tests. A possible gob application may require that 750 cfm of methane be consumed during periods of maximum outgassing. It is premature at this time to accurately scale from laboratory to mine application.

Jan 1, 1991

By John F. Martonik

When OSHA came into existence in 1970, it adopted national consensus standards to improve safety and health conditions in work places. Coke oven emissions, which are proven to cause cancer and respiratory diseases, were regulated by the coal tar pitch volatile standard, adopted from the 1969 edition of the Threshold Limit Values for Airborne Contaminants by the American Conference of Governmental Industrial Hygienists. The coal tar pitch standard, based upon the benzene soluble fraction of total particulates, limits the personal exposure to 200 micrograms of the benzene soluble fractions of total particulate per cubic meter of air. This standard can be classified as a performance standard because only general limits are set which allows the employer to choose for themselves the means to comply. Both the United Steelworkers of America and the American Iron and Steel Institute petitioned the Secretary of Labor to write a new standard for coke oven missions, each thinking the coal tar pitch standard unsatisfactory.

Jan 1, 1980

By M. Myers, T. Oxley

Price, lead-time, efficiency, availability, maintainability. These are all the factors involved in the selection of components for a conveyor system in a mining operation. Historically, the decision-makers do not consider all these factors together when it is time to procure the equipment needed to assemble a conveyor system. The Total Cost of Ownership approach enables an operation to attain superior efficiency and desirable maintenance practices, all while minimizing the total cost to operate and maximizing the return on investment.

Jan 1, 2003

By Ryne Goodnough

INTRODUCTION The Wyodak Mine is located in the northern Powder River Basin of Wyoming and is thought to be the oldest continuously operating coal mine in the United States, having recorded yearly production since 1923. The mine has expanded over its 80-plus-year history from an underground room and pillar operation to a modem surface snip mine. Currently, the mine feeds four on-site power plants using conveyors, has a filly automated truck load-out, and ships coal by rail to nearby Wyoming power plants. Annual production of 4.8 MTFT is accomplished on a single-shift basis with 53 fill-time production, maintenance and administrative personnel. In 1990 a decision was made to modernize the coal feed system to the power plant complex with modular conveying equipment. The project involved constructing coal storage silos, overland conveyors, feeder breakers and modular conveyors to follow the mining benches. Total project cost in excess of $25 million was used to construe or commission: A 2,150-TPH 48-inch overland conveyor with horizontal curve A 2,150-TPH 48-inch plant feed conveyor 13 shuttle conveyors, each 150 feet in length 2 front-end loaders equipped with large coal buckets 2 crawler-mounted feeder breakers with compatible discharge conveyor 1 high-lift shuttle conveyor with adjustable discharge height 1 high-angle conveyor 2 4,500-ton coal silos with automated truck load- out capabilities. Conceptually, the plan was to develop 33 MTONS of reserve adjacent to the plant complex and use front-end loaders to tram ROM coal to in-pit feeder breakers. The primary crushing would reduce coal to 6-inch minus and feed through a series of shuttle conveyors to an overland supply conveyor. The overland conveyor would feed the secondary crusher, and the crushed product would be moved to any of four storage silos using conveyors. The in-pit crushing and conveying system is a unique fit for the power plants and provided many interesting challenges for the coal mine to overcome. System integration, maintenance windows, equipment availability and the like had a major role in engineering the system to a power plant complex having no emergency coal stock- pile and limited plant storage. In crediting the designers and operators, the in-pit conveying system at the Wyodak Mine has delivered coal to the power generators since 1994 with little or no downtime. ENGINEERING CONSIDERATIONS Yearly production for the mine is based on 3.5 MTPY which requires about 1,550 TPH on an 8 hour, one-shift- per-day, 5-days-per-week basis. Considering efficiencies for starting and stopping, crew transport, loader trams, and operational delays, a nominal conveyor feed rate of 2,150 TPH or 72% system utilization was used in engineering design application. This ton-per-hour basis is used to size and commission the remaining components of the in-pit system. Coal quality requirements also played a role in equipment selection. The mine reserve grades vertically and coal from Upper and Lower benches needed to be mixed in any given proportion. This required equipment to be filly variable and capable of producing all or part of the 2,150-ton-per-hour requirement. Bisecting the 80-foot- high coal face for quality required construction of a high lift module capable of reaching a single overland conveyor 40 to 50 feet above the pit floor. Designers built a high-lift, adjustable and portable module specific for this application Having two bench systems capable of each producing the required feed for the power plants required computerized control processes to control on-line production. RSLinx, RSLogix, and RSView were chosen as the communication and control software, and a Data Highway Plus serves as the communication backbone. Each of the two in-pit benches are controlled with a data center equipped with Allen Bradley 5-40 processors. This

Jan 1, 2004

By L. Xu

Since the establishment of the standard dust concentration of 2 mg/m3, a strong effort has been made by mining engineers and researchers to provide better dust control equipment and procedures for underground coal mines. Particular areas of success have been control of dust generation by better coal-cutting strategy, better design of water sprays for dust suppression and air movement, use of scrubbers, and improved design of face ventilation systems. A drastic improvement occurred over time such that the average dust concentrations for continuous miner operators dropped from 6.5 mg/m3 in 1968 to 1.3 mg/m3 in 1980 and for auger, cutter, longwall, and roof bolter occupations from 2.7 mg/m3 in 1973 to 1.6 mg/m3 in 1980 (Niewiadomsky, 1983).

Jan 1, 1990

By P. K. Ackerman, F. F. Aplan, G. H. Harris, R. R. Klimpel

Fourteen reagents that are potentially capable of chelating with a metal ion on the surface of the major copper sulfide minerals and pyrite were evaluated for their effectiveness in floating these sulfides. The reagents studied fall into the classes of mercaptobenzole mutations, thiouronium, thionocarbamates, thiourea, imidazole mutations, oximes, hydroxyquinoline and xanthogen formate. The best overall copper sulfide collector was an imidazoline (1-Hydoxyethyl - 2-Heptadecenyl), but it also proved to be an excellent collector for pyrite. Its potency as a pyrite collector can be reduced by structural alteration, but at some loss in its collecting power for the copper sulfides. The effectiveness of many of these potential collectors can be changed by minor alterations to the collector molecule and, to a lesser extent, by pH adjustment. The general order of mineral floatability with these reagents is chalcopyrite = chalcocite > covellite =bornite >> pyrite. The flotation of malachite is generally similar to that of the copper sulfides, indicating the special effectiveness of copper in the crystal lattice for collector attachment.

Jan 1, 2000

By H. Colijn

Belt conveyors have proven themselves for many years as a dependable and low cost method of handling bulk materials at high flow rates. The success of a belt conveyor system greatly depends on the initial loading of the material on the belt. If the material is loaded on the belt at the center, at approximately the same speed and with minimum impact, then most of all belt conveyor problems disappear. Proper belt loading is primarily determined by the engineering and design of the conveyor transfer point. This paper will establish and discuss some general design criteria required for proper loading and transfer of materials from one conveyor to another. Specific attention is given to loading points, chutes, skirt board length and general design of transfer structures.

Jan 1, 1971

By David W. Wisecarver

Kennecott Copper Corporation and the U. S. Bureau of Mines cooperated in a full-scale slope stability research project at the Kimbley Pit near Ely, Nevada. The west wall of the Kimbley Pit was mined from an over-all slope angle of 45° to an over-all slope angle of 57° and the pit was deepened nearly 50 feet. Mining was begun February 10, 1966, and completed October 30, 1966. Approximately 2.55 million tons of ore and waste were mined. The project was designed and carried out to learn more about the behavior of a pit wall as its slope angle is steepened and to obtain a possible insight into engineering parameters for use in design of future slopes. Data from this project are presented as obtained from (1) instruments installed in two adits for deformation and displacement measurements, (2) a subsidence network installed on the surface above the steepened wall, (3) pre- and post-mining observations of stress in rock, (4) sonic-velocity measurements, and (5) seismic and microseismic investigations. Changes occurred in measured quantities as the slope was steepened but stopped when mining was completed. Agreement was noted between the measured changes and predicted changes obtained from calculations using the finite element technique. Subsidence surveys and microseismic studies show the steepened pit wall to be stable.

Jan 1, 1968

By R. E. Gertsch

Mechanical mining holds great promise for the mining industry. Realizing this promise depends on giving mine operators the capability to evaluate the higher production, the lower costs, and safety enhancement that comes with mechanical mining. The opportunities for low cost and high production must outset the high capital costs associated with mechanical excavation. Giving the mining industry the tools to effectively evaluate and successfully implement mechanical methods defines the challenges and directions of the mechanical mining industry.

Jan 1, 1994