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By J. W. Danni

Today's mining industry faces many challenges. Perhaps none is more important than the challenge of improving our industry's public image. Opinion polls document public concern for a clean and safe environment. As part of that public, the mining industry must share that goal. The public is now the most powerful environmental group in society. And the public wants the environment to be protected. In May 1989, Edgar S. Woolard, chairman of DuPont, spoke to the American Chamber of Commerce. He said that industry's continued existence "requires that we excel in environmental performance and that we enjoy the non-objection - indeed even the support of the people and governments in the societies where we operate." In effect, Woolard called for "corporate environmentalism." He defined it as an "attitude and a performance commitment that places environmental stewardship fully in line with public desires and expectations." Environmentalism is no longer a fringe activity, but rather is now clearly in the mainstream. How can we meet public expectations and improve our image as an industry? One of the best ways is to plan, design and operate our mine facilities with environmental responsibility and social concern. The Mineral Hill Mine provides a good case study of a facility that has made this commitment. The project used an inter-disciplinary, multiagency task force, citizen advisory groups and engineering and design considerations. As a result, Mineral Hill achieved cost-effective permitting. At the same time, the operation demonstrated effective "corporate environmentalism."

Jan 1, 1992

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 M. S. Basich, J. S. Scope1, J. H. Raeder

During 1983, The Youghiogheny and Ohio Coal Company's lost-time-incidence rate was 8.1, equal to the average for underground bituminous operators. How- ever, one half of all lost-time injuries were low back, back and neck related. In reviewing these results, we determined that substantial improvement could be made. We investigated existing back schools and the possibility of opening an in-house clinic. In September 1984, we began The Youghiogheny and Ohio Coal Company's Back Care Program. The objectives of the program are to reduce the number of back injuries incurred at the work site, hasten recovery time, decrease medical and workers' compensation costs and provide the employee with a thorough understanding of his problem. A state-of-the-art clinic capable of treating injuries to the spine and extremities has been established at the work site. The clinic is staffed by a licensed physical therapist and is offered to all employees on a voluntary basis under physician referral. The approach to treatment is multi-phasic. For the typical patient, the initial goal is to reduce pain and correct dysfunction. Treatment modalities such as auto-traction, extension exercises, ultra sound and moist heat are frequently used. During this period the patient is given extensive education regarding his problem. As soon as more vigorous activity can be tolerated, a work-hardening pro- gram consisting of job simulation activities designed to improve flexibility, strength and functional capability is begun.

Jan 1, 1986

By Byron N. Cooper

The Revenue Act of 1926 provided for five simple categories of natural resources to have the benefit of depletion allowances. In the 1947 Revenue Act, the number was increased to twenty-five, and in the 1951 Revenue Act to fifty-four. Of this number, fourteen were allowed 5 per cent; nine, 10 per cent; twenty-nine, 15 per cent; one, 23 per cent; and one (oil and gas), 27.5 per cent. The 1951 Revenue Act created a host of difficulties, including application of the "end- use criterion" and determination of the commonly accepted meaning of such terms as limestone, dolomite, chemical- and metallurgical-grade limestone, marble, calcium carbonates, and magnesium carbonates. Dolomite, for example, was listed at 10 per cent depletion allowance, but without definition. In the great amount of litigation growing out of the 1951 Revenue Act and its administration, it became essential to understand the derivation and subsequent usage of these common geologic terms. One thing that became clear was that our definitions changed significantly between the time that the 1951 Revenue Act became law and the time that later cases were tried. Some geologists neglected to learn about first usages of such terms as metallurgical limestone, and about meanings that were applicable when the 1951 Revenue Act was written and passed. Legal meanings in this paper are discussed in the light of certain famous cases that have been tried and settled.

Jan 1, 1966

By Don U. Deere, Edward J. Cording

INTRODUCTION Observations during construction form an integral part of the design and construction of major underground works. Observations as used herein include visual inspection, detailed geologic mapping, and correlation of geology with support conditions, as well as instrumentation to provide more precise information regarding rock movements and support load. This paper describes the application of an observational program to one of the more difficult design and construction problems underground -- the excavation and support of large chambers at shallow depth in rock of variable quality. Emphasis on underground construction for subways and utilities in urban areas is bringing this problem to increased prominence. It is our intent to focus on the design and construction problems associated with such excavations and to describe observational methods which can be employed to aid in their construction. Observational programs may serve two purposes. One is to monitor the rock and support conditions in order to provide early warning of potential construction problems. Such a program should be routinely used in critical locations on major underground excavations of the type described in this paper. The program should be closely coordinated with the inspection effort and construction control. The other purpose is to provide detailed information regarding the interaction of support conditions and rock displacements to aid in development of more efficient design and construction procedures on later projects. For this purpose, instrumentation might be concentrated in special test sections where specific and typical

Jan 1, 1997

By J. F. T. Agapito, J. B. Page

This paper describes part of a geotechnical study based on stress determinations and convergence measurements conducted to assess the long-term stability of an experimental room-and-pillar oil shale mine. A rock mechanics program was initiated in 1971 at the Colony Mine as part of a large study conducted for the design of a commercial operation. The Colony Development Operation is a joint venture currently consisting of four active members; Ashland Oil Inc., Atlantic Richfield Company (Operator of the project), Shell Oil Company, and The Oil Shale Corporation. Although oil shale commercialization plans are presently suspended, rock mechanics instrumentation has been continued as part of Colony's policy in maintaining readiness to proceed with a commercial shale oil plant when national energy policies became better defined. The property is located in the southern edge of the Piceance Creek Basin in northwestern Colorado, approximately 200 miles west of Denver. Experimental mining operations were conducted from 1965 to 1972 with one of the major objectives of the pilot mine being the assessment of opening and pillar sizes for the determination of extraction ratio and life of the property. Mining was conducted in a 60 foot thick portion of the Mahogany Zone in the Parachute Creek Member of the Green River Formation, at depths of 600 to 850 feet by a one-bench system. Pillar dimensions were 58 feet by 58 feet and rooms were 55 feet wide.

Jan 1, 1977

By John W. Ahlrichs, E. Daniel Baker, Erich U. Petersen, William J. Tafuri, Douglas N. Halbe

The combined Bootstrap and Capstone deposits, located in the Bootstrap subdistrict (Section 10, T36N, R49E, M.D.B.M., Elko County, Nevada), are approximately 27 miles northwest of Ca-1I: Nevada. The contiguous Bootstrap Capstone deposits are located along the northeastern and northern flanks of Round Mountain, a horst block separated by grabens from the sheep Creek Mountains to the north-northwest and the Tuscarora Mountains to the east. Open-pit-minable gold reserves as of December, 1989, were 13.27 million short tons with an average grade of .057 troy ounces gold per ton and an overall waste-to-ore strip ratio of 2.5:1. Ore zones in Bootstrap are concentrated along north striking high-angle dikes localized along faults, while ore zones at Capstone are strata form and structural, occurring at the Devonian limestone/siliceous sediment interface and in high-angle fault-filling dikes. Pre-ore faulting produced a complex structural setting for Capstone, dominated by strong northwest fault sets cross-cut by northeasterly structures. Alteration associated with both deposits is silicification with a-strong argillic overprint. Dike emplacement, which post-dates silicification, marked the onset of mainstage gold deposition and argillic overprinting of silicified lithologies. Gold displays an affinity for moderately argillized sedimentary and igneous lithologies. Mineralogic and geochemical analyses of rotary percussion drill samples show good correlation between gold, silica, antimony, and arsenic.

Jan 1, 1990

By V. Roze, M. E. A. Robertson, C. J. Sharland

Current Techniques - Fire Assay Fire assay of gold has been used for several thousand years and is a well known technique to the traditional assayer. Very few assayers wish to use the method but to date there has been no viable alternative. Fire assay is expensive in labour, time, capital and running costs. Workers can be exposed to hazards and uncomfortable working conditions such as lead fumes, heat stress, dust and eye strain. The high capital cost of putting up the building and equipping it, together with running costs which increase annually at a prohibitive rate makes the technique less attractive each year. The main requirement in most assay laboratories is to maximise throughput economically. This is difficult with fire assay as it is impossible to automate. Each sample for analysis is handled by at least 12 people and each person represents a potential source of error. Record keeping and report generation has to be done manually which is both slow and prone to errors. Replacement of staff requires a considerable training period and with a large turnover of personnel this presents yet another problem. The presence of silver and dross in the gold sample affects the accuracy at low gold values. X-ray fluorescent analysis Two methods of XRF instrumentation have been used with limited success. The first type is a laboratory instrument employing L X-rays. Small samples of a few grams, which are not representative,

Jan 1, 1988

By B. R. Reddy, P. V. R. Bhaskara Sarma

A process for the separation and recovery of cobalt and nickel was optimized for a sulfate leach solution of Indian Ocean sea nodules containing 80 g/m3 cobalt and 730 g/m3 nickel using the sodium salt of Cyanex 272 as the extractant. Extraction of both cobalt and nickel increased with an increase in equilibrium pH and extractant concentration. The extracted species with respect to cobalt appears to be CoA2.3HA. More than 99.6% extraction of cobalt was achieved using 0.04M solvent in a three-stage counter current simulation at the A:O phase ratio of 3:2. The co-extraction of nickel was about 0.6% only. Two-stage countercurrent stripping of cobalt from the loaded organic at an A:O ratio of 1: 7 resulted in a pregnant electrolyte enriched by 0.8 kg/m3, thus enabling a ten times overall enrichment of cobalt. From the cobalt free raffinate, nickel extraction was carried out using 0.25M solvent in two countercurrent stages, and the extraction showed a 99.8% recovery. Stripping of nickel from the loaded solvent was carried out at an equal phase ratio with the advance electrolyte of pH 1.75 in two countercurrent stages. The nickel stripping efficiency was found to be 98.8%. The present studies indicated that complete recovery of cobalt and nickel was possible using nine counter-current stages.

Jan 1, 2002

By Joseph M. Tarantino, Eric F. Perry, Keith B. C. Brady, Michael W. Smith

The Pennsylvania Department of Environmental Protection in 1998 reviewed its permitting process to determine how effective its program has been in preventing pollution and to identify here it could be improved. Of the 1,699 bituminous mine permits issued from 1987 to 1 996, 50 were identified to have current or past postmining discharges with water quality problems. The remaining 1,649 sites had no known current or past postmining discharges problems. The 50 sites were selected for further review. On closer examination, 33 of these permits no longer had water quality problems or the problem had not actually resulted from the permitted mining activity. Only 17 permits, or one percent of the total permits issued, were found to have caused long-term postmining discharges serious enough to require treatment and prevent bond release. Analysis of these 17 sites using current knowledge of mine drainage prediction, revealed that the most common cause of error was inadequate information in the permit application. Errors in interpretation of the application data and in implementing the permit were less common. A very small percentage of all permits issued resulted in postmining discharges for no clearly identifiable reason. Trends over the 10-year study period indicated a decreasing incidence of permits resulting in postmining discharges. Further, with the exception of the first few years of data, most of the postmining discharges were of mildly acidic or alkaline quality and amenable to passive treatment.

Jan 1, 2000

By E. Bane Kroeger

Plane failure in rock and soil slopes is usually caused by the intersection of a discontinuity plane with a slope face. Normally, these discontinuities are weaker than the surrounding intact rock and provide a surface along which movement can occur. The discontinuities are typically analyzed to determine the stability of a particular slope. One problem that arises when evaluating the stability of a planar feature is that the method for planar analysis is two-dimensional and has difficulty dealing with planes that are oblique to the slope face. Several researchers have stated in the past that planar failures are a special case of wedge failure. Wedge failures occur when two planar discontinuities intersect in an unfavorable manner. Sliding can occur along the intersection of the planes. Wedge failures are very common in rock slopes and can often be problematic. Wedge stability analysis methods are typically three-dimensional and can analyze planar features that are very oblique to the slope face. Wedge failure analysis can also be used to determine the stability of planar features with good success. One advantage to using wedge analysis over plane analysis is that a tension crack can be both non-vertical and oblique to the slope face in the wedge analysis. This allows the engineer to more closely match field conditions. It also negates the need for the engineer to have two separate software packages to analyze a single slope, saving both time and money.

Jan 1, 2002

By Leonid P. Ni, Askar M. Kunayev

It is well known that processing of the high-silicon bauxites for obtaining alumina by the hydrochemical Bayer process is irrational due to the significant losses of alumina and alkali with red mud. The main source of losses of the mentioned compounds under the conditions of leaching by the Bayer process is the formation of difficultly soluble sodium alumosilicate of the composition Na20 .Al203, 2Si02 . n H20. A conventional method of an extra recovery of alumina as well as of regeneration of alkali out of red mud is the high-temperature sintering of the latter with soda and limestone with the subsequent leaching of sodium aluminate from the sinter by water or soda solution. A sequential version of the Bayer-sintering flow chart recommended for the prosessing of bauxites with an increased content of silica is based on this method. However, the sintering method is not the only alkaline method allowing to make an extra recovery of alumina likewise of alkali from red mud. Our investigations showed/I/, that the components mentioned can be recovered by a pure hydrochemical method of treating red mud with concentrated alkaline solutions, with lime (Ca0) being present, that was earlier succesfully used in the development of the hydrochemical method of processing nepheline rocks/2/. The possibility of extracting alumina and alkali from red mud is based on the reactions which can be schematically represented in the following way:

Jan 1, 1984

By A. F. McKown, P. E. Sperry, W. L. Fourney, D. E. Thompson

INTRODUCTION Underground drill and blast excavation is usually accomplished with small diameter holes loaded with high energy explosives. The detonation pressures are extremely high and an extensive amount of energy is dissipated in the process; however, very little of this energy is used to create the specified fracture planes required for excavation. The available energy is expended in producing radially outgoing stress waves, in crushing the adjacent rock, and in producing a dense, randomly oriented radial crack pattern about the holes. This causes several undesirable effects: 1. Overbreak at the perimeter, which results in more muck to remove and extra concrete or shotcrete to fill the voids. 2. Damage to or loosening of the remaining rock at the perimeter which may result in the need for additional support measures. 3. Ground vibrations and/or airblast, which could result in damage to nearby structures and complaints by people living or working in the area. Several steps may be taken to minimize these effects. Where control of the perimeter is desired, smooth blasting techniques are generally employed in which the spacing and burden of perimeter holes are reduced and lighter, decoupled charges are used. Where vibration damage to structures is feared, control is generally exercised by limiting the charge weight per delay period so that the ground vibrations at the nearest structure do not exceed a peak particle velocity of two inches per second. Where blasting complaints may be a problem, con-

Jan 1, 1979

By H. C. Verakis, T. E. Lobb

During the past decade, approximately 5 billion pounds of explosives were used annually in the United States. Most of this quantity of explosives was used by the mining industry, with coalmining being the dominant application for explosives. Considering the large amount of explosives used, the accident safety record for the mining industry has improved significantly over the past several decades. Although blasting accidents usually represent a small percentage of the total number of mining accidents, they continue to occur and the severity of these accidents is disproportionately high compared to the other mining accidents. This paper is an analysis and summary of mine blasting accidents over the past several decades as they relate to surface coal mine operations. A compilation and review of surface mine blasting accidents from1978 through 2001 was made. The accident data was examined to identify the trends and primary causes, which continue to be blast area security, fly rock, premature blast, and misfires. Approximately 46percent of the causes of surface coal mine blasting accidents are attributed to blast area security, while fly rock, premature blast, and misfires represented an additional 50 percent of the causes. Accident categories were established based on the cause of the accident or the activity that was taking place when the accident happened. A discussion of the accident data is presented to increase hazard awareness and to emphasize safe blasting practices and MSHA requirements concerning mine blasting operations.

Jan 1, 2003

By Howard M. Cotton

Early in 1977, Amoco Production Company and Houston Chemicals, a subsidiary of Pittsburg Plate Glass (PPG) Industries, started producing iodine commercially in northwestern Oklahoma. This is significant because it is the first plant in over 40 years to be built in the United States with iodine as its sole commercial product. With the exception of a limited amount of iodine produced by Dow Chemical in Michigan, the United States is dependent upon imports from Chile and Japan for its iodine needs. The two million pounds of iodine produced annually from the Woodward plant will supply over one-third of the United States' requirements. Routine analysis of subsurface brines by the Formation Water Lab at the Amoco Production Company Research Center in Tulsa, Oklahoma, revealed unusually high concentrations of certain potentially economic minerals. Investigations determined that, of the minerals in question, iodine appeared to offer the best potential. The brines in question are located in the Morrow sands (basal Pennsylvanian) at a depth of 7,175 to 7.400 feet, in an area where Amoco has been active in a gas play for the past 20 years. The regional iodine concentration ranges from 10 to 700 ppm and averages around 300 ppm with the project area. The project is located 8 miles north and slightly east of the town of Woodward, where the well-developed, porous, and permeable sands of the Woodward trench contain large volumes of brine.

Jan 1, 1978

By S. P. Banerjee

By international standards, Indian coal seams are not very gassy. In some of the major coalfields such as Singareni, Wardha, Pench, Chirimiri, Rewa and Talcher Coalfields practically no methane is emitted from the coal seams. Even in the coalfields of Ranigang, Jharia, Bokaro and Karanpura, all of which are situated in the basin of the Damodar river, only a few mines are faced with excessive gas emission problems. But the number of such mines is increasing as deeper reserves are being worked and already the exploitation of some of the best quality coal reserves in the country is held up pending measures for control of methane emission in these mines. Even in mines having no previous history of gas emission, methane has been met near dykes and faults. This was dramatically revealed by an explosion in Dhori colliery in 1965 wherein 268 persons got killed. Until that time, Dhori colliery was considered as a non-gassy mine but on that fateful day gas came to the workings through a freshly exposed fault plane. Similar incidences of ignition of firedamp in so-called non-gassy mines have also occured in the past, for example, in Chapui Khas and Samla Dalurband collieries, but the casualty figures were not as high. After the Dhori explosion, all Indian coal seams have been declared to be gassy, whether presence of methane is detected in the workings or not.

Jan 1, 1980

By Andrzej Wala

Constantly increasing demand for energy materials and metal ores brought about tremendous progress in mining techniques which are characterised by a high degree of mechanization and concentration of works. One of the recent trends in underground mining mechanization is connected with an application of heavy machines with diesel engines [l],[2]. The introduction of diesel engines in mining all over world caused not only improvement in economic conditions but also the necessity to prevent contamination of air in the mine by toxic agents in diesel exhaust emissions. A generally used way of eliminating exhaust gases is proper ventilation of the cross cut by means of providing permanent exchange of air that would guarantee in every point of the cross cut and in every moment the decay in concentration of exhaust gases beyond threshold limit [3][4][5][6][7][8][9][10]. The present paper is an attempt to define a mathematical model describing the changes of concentration in cross cut face to which fresh air is distributed by ventilators and tubes in a forcing way. Obtained model should offer its practical adaptability to engineering calculation of the amount of fresh air needed for diluting and eliminating exhaust gases beyond threshold limit. Justness of these models has been confirmed by investigation of the growth of nitrogen dioxide concentration in air environment in some cross cut faces of Kiirunavaara iron ore mine in Kiruna (Sweden).

Jan 1, 1980

By K. Norrena, E. Magri

An important problem in mine operations is the classification of material as waste, low-grade stockpile and ore. This classification must often be made with blasthole data that are widely spaced and that have sampling errors. Geostatistical-simulation techniques combined with basic economic principles allow a procedure for classification that maximizes the expected profit. Geostatistical-simulation methods (Gaussian, indicator or annealing-based) allow the integration of hard and soft data in the creation of alternative, equally probable realizations of the mineral grades. At each location, for each realization one calculates the "profit" if the block were to be classified as ore or waste. The optimal classification is the one that maximizes expected profit (a maximum profit selec¬tion or MPS procedure). In this paper, the authors discuss the theoretical justification of the method and implementation details. The use of blasthole data from different types of mineral deposits, that is, different levels of continuity, are considered. The authors also show the efficacy of the procedure with different levels of sampling error. The increased revenue due to the MPS procedure and improved sampling is shown. The paper shows the geostatistical-simulation procedure and the uncertainty in block grades that result from incomplete and imperfect sampling. The optimal classification is presented. Optimal block classifications are transferred to realizable dig limits by hand-drawing polygonal boundaries. The results of the proposed method are compared to classification based on kriging. Limitations and areas of future work are identified.

Jan 1, 2000

By Pieter Barendsen

INTRODUCTION One of the main problems in tunneling without the use of explosives lies in the development of tools which, at an economically acceptable level, are capable of continuous breakage of the rock, resulting in a fragmentation suitable for a smooth, uninterrupted transportation of the muck away from the tunnel face. Tools employed on tunneling machines have, so far, always been of the mechanical kind which break up the rock by a crushing and shearing action. Other methods of rock breaking are possible but, even if some of them have reached the laboratory testing stage, nearly all of them are still too "exotic" to be of any practical use in the immediate future. One must admit, however, that some highly interesting results are beginning to be reported from the USA on the use of high pressure water jets for the destruction of rock through erosion, a field pioneered in Europe(USSR and Great Britain). Mechanical breakage of the rock is effected by inducing stresses exceeding its compressive/shear strength, by loading it with a wedge of cone shaped tool, until cracks are formed and chips loosened. In order to allow the tools to act upon the rock face continuously, they are commonly shaped as rotating bodies, "roller bits" or "disc cutters", spinning freely and mounted on a revolving boring head of tunnel diameter. The thrust of the tools against the face is generally exerted in a direction which is parallel to the tunnel axis.

Jan 1, 1997

By R. H. T. Garnett

Recovery performance may be measured in absolute terms or in relative ones that relate the actual mining outcome to what was expected. Consideration is possible in terms of the control exercised by the operator. The eventual mineral output is the only figure known with complete certainty. The paradox is that, while performance is judged against the sampling, the reverse also applies. The R/Efactor and its four component factors are the best overall measures of performance. The choice of equipment for sampling and mining is very important. The sampling process may introduce errors and the sample density may lead to poor mining block selection. The resulting recovery performance is most visible on a regression curve. Changes in the cutoff grade must also be taken into account to avoid unrealistic production targets. Estimation methods incorporating different mathematical assumptions and techniques may cause over-or underestimation of the grade and volume. If the selective ability of the mining equipment does not match the size of the reserve blocks, the performance will be compromised. The treatment plant efficiency, the throughput rate and the degree of bedrock clean-up also affect performance. The maximization of throughput does not yield the optimum results. Marine conditions, which are outside the operator's control, affect not only operational availability but also performance. Examples are provided from actual operations for various commodities, showing the relative magnitude of the different effects upon performance.

Jan 1, 1999