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By Keith A. Heasley, John L. Ellenberger, Paul W. Jeran

In this paper, a state-of-the-art, three-dimensional, full waveform, microseismic system was used to analyze the rock failure around a deep (> 750 m (2500 ft) of cover) bump-prone longwall panel. The microseismic system consisted of both underground and surface geophones coupled through radio telemetry and a fiber-optic network to produce pseudo real-time detection and location of seismic events surrounding the coal seam. This was the first microseismic installation of this scope at a U.S. coal mine, and the system was intended to help determine the exact strata mechanics associated with the redistribution of stress and the associated gob formation at one of the U.S.’s deepest longwall mines. Overall, 5,000 calibrated seismic events were recorded during the mining of one panel, including a Richter magnitude 4.2 event which occurred inside of the array. Analysis of these events provides a number of notable insights into the rock mass behavior. For instance, the longwall panel was widened during the retreat process, and the mining-induced seismicity shows a distinctly different behavior between the start of the panel, the mining of the narrow part of the panel and the mining of the wider part of the panel. Also, in itself, the acquisition of the ML 4.2 event was a major milestone in geomechanical and bump research. This is the first time that such an event has been recorded with this detail and accuracy at a bump-prone coal mine in the U.S. The analysis of this single event has set distinct new limits on the relationship between mining seismicity and coal bumps.

By F. N. Voskoboyev

The suggested new method for control of geomechanical state of undermined rock mass ensures, as a safety measure for the earth surface protection, the decrease of deformations by 2,5 - 10 times in mining the single seam, and by 1,5 - 5 times - in mining bed series, i. e. approximately within the seam ranges as in the application of full packing with various compressive properties or partial extraction of resources over the area with different coefficients of extraction. It should be noted that this new method has the following advantages o\w rhr. conventional methods: a) the decrease of the packing area and packing works volume by 2 - 4 fold including the operating and productive expenses; b) the elimination of mineral losses due to the increase of extraction coefficient up to 100 5%; c) rock utilization from workings drivage by its placing in the mined - out space. Perspective field of application of this method: disconservation of mineral resources in the left protective pillars of various designation.

Jan 1, 1996

Coal research and technologic work by the Bureau of Mines covers a broad program of investigation aimed at conservation and utilization of this important natural resource. Conservation is served by a constant search for higher efficiencies in mining, preparation, and use. Increased utilization is sought through various projects that probe new ways to use coal and expand existing coal markets. This report, the twenty-eighth in the series,3 gives the highlights of Bureau of Mines coal research and technologic work in 1963. The scope and complexity of the program makes it virtually impossible to report all progress on every project, even tor a 12-month period. Full insight into each project can be gained only through intensive review of basic objectives, past accomplishments, and current status of the work. Details of the work are given in numerous publications issued by the Bureau and its laboratories and centers located throughout the country.

Jan 1, 1964

Coal research and technologic work by the Bureau of Mines covers a broad program of investigation aimed at conservation and utilization of this important natural resource. Conservation is served by a constant search for higher efficiencies in mining, preparation, and use. Increased utilization is sought through various projects that probe new ways to use coal and expand existing coal markets. This report, the twenty-eighth in the series,3 gives the highlights of Bureau of Mines coal research and technologic work in 1963. The scope and complexity of the program makes it virtually impossible to report all progress on every project, even tor a 12-month period. Full insight into each project can be gained only through intensive review of basic objectives, past accomplishments, and current status of the work. Details of the work are given in numerous publications issued by the Bureau and its laboratories and centers located throughout the country.

Jan 1, 1964

By C. W. Davie

"This paper is the second of a series of progress reports4 on a study of the hydrometallurgy of manganese which is being conducted in an endeavor to make possible utilization of the large deposits of low-grade domestic manganese ores that occur in several States.There are at least four processes in which a knowledge of the action of SO2 gas on manganese oxides at elevated temperatures may prove of value.One of these involves dissolution of manganese from ores. The Bureau of Mines has investigated the hydrometallurgy of manganese by a process in which SO2 gas, a waste product at many smelters, is passed into water to form a solvent for manganese. Although several manganese minerals were readily dissolved, rhodochrosite (MnCO3) was attacked but superficially.5 Recent experiments have shown that a roast at 650 to 9000 C. converts the manganese of rhodochrosite to a form that is quickly dissolved by a weak SO2 solution.6 Introduction of smelter gases containing much as 5 per cent SO2 during such a roast would not add much to the cost of the operation, and might result in the formation of considerable water-soluble manganese sulpate.Another case involves a subsequent step in the hydrometallurgical process, namely, the formation of oxides of manganese with simultaneous evolution of SO2 by the heating of the MnSO4 produced by evaporating its solution.A third has to do with the roasting of zinc sulphide ores containing manganese as a preliminary to leaching. During purification of the solutions to be used for the electrolytic deposition of zinc the iron must be oxidized to make possible its removal. Manganese dioxide has been used for this purpose,7 and since manganese compounds are present in some zinc concentrates,8 it is of interest to learn what happens to the manganese in a zinc sulphide or on roasting, and what portion of the manganese in the roasted product might be available for oxidation."

Oct 1, 1930

By Steve Colbum

LTl’s MapStar LPS (laser positioning system) utilize both tripod mounted and hand held reflectorless distance meters. These are eye safe, easy-to-use, and specifically designed to endure the harsh environment characteristic to the mining, quarry and explosives industries. Survey data collected by the systems is digitally stored in a ruggedized data collector and then processed with a specialized, interactive software program, which can be run on any standard PC. Win Prof, the Windows-based analytical software package is used to reduce the data for generating bench face profiles, surfaces, volumes, estimating true burdens and mining ratio calculations. In addition, the software has many other built-in routines to calculate powder factors, toe shear, to map structural contacts and to predict the flyrock potential based on the Burden to Energy ratios. An extensive, built-in library of explosive’s data facilitates these calculations. It will also conform automatically to user-specified minimum and/or maximum burden in relation to the explosive energy, hole diameter and bench geometry - for both vertical and inclined holes. Numerical data can be represented in 2D or 3D to emphasize the hole-burden-face relationships.In this workshop, the MapStar LPS instruments and Win Prof analytical software will be thoroughly demonstrated. Demonstrations include equipment configuration, typical field setups and several effective survey procedures, including processing of some sample data.

Jan 1, 2000

By L A. Maslov

We have considered the following characteristics of the crust and upper mantle of the Pacific Belt: seismic wave velocity anomalies, mechanical stress and shear deformation rate fields, heat flow and the pattern of metallogenic provinces of the Belt. It has been noted that there exist certain .regularities in distribution of the above mentioned geophysical characteristics and metallogenic zones within the Belt, displayed by prevalence of the lithophile elements in the Asia-Australian part of the Belt, and of the chalcophile ones within the American part.

Jan 1, 1995

By Lawrence J. Froisland

To aid in minimizing adverse environmental impacts of mining and mineral processing, the Bureau of Mines studied changes in soil characteristics in topsoil stockpiled during mining operations. Topsoil stockpiles in arid areas of New Mexico, Utah, and Wyoming were sampled over a 1- to 8-yr period to determine any changes in physical, chemical, or biological parameters in the top 15 ft of soil. Parameters examined in this study included soil moisture, pH, electrical conductivity, and cation exchange capacity; total nitrogen, organic carbon, carbon to nitrogen ratio, extractable potassium, and soluble phosphorus levels in the soil; general levels of bacteria activity in the soil; and productivity of the soil as measured by shoot yield in growth tests. Data were analyzed by multiple linear regression to determine possible effects of stockpile age and depth. Bacteria population counts, used as an indicator of goner l bacterial activity, was the only parameter found to be significantly correlated with stockpile age and depth at more than one site. Bacterial activity increased with depth at the two sites where it was measured. Activity increased with age at one site and decreased with age at the second. Significant changes in soil pH, electrical conductivity, and moisture were significantly correlated with stockpile age and depth at single sites. This study did not show significant, consistent deterioration in soil characteristics or growth yield of topsoil stored in stockpiles.

Jan 1, 1987

By M. A. Stoakes, H. D. S. Miller

Surface subsidence is becoming an increasingly important factor in the economics of mining Louisiana salt domes due to, amongst others, excessive shaft deformations and land loss to encroaching sea water. The vast majority of subsidence studies have been undertaken on bedded, tabular deposits. It is important to understand the causes of subsidence due to mining domal salt and how it can be minimized. The paper will review the major differences between subsidence caused by domal and tabular evaporite mines, the problems encountered in predicting subsidence, the factors that influence subsidence and, finally, possible alternative mining methods.

Jan 1, 1986

By A. L. Foote

This is the final report of work accomplished during 1973-75 under U. S. Bureau of Mines Contract No. H0242015, "System for Handling Underground Mine Supplies and Materials." The purpose of the contract was to develop a mechanical device which could safely perform handling tasks that are normally done manually in underground bituminous coal mines. The report discusses studies leading to construct-ion of a battery-operated, three-wheel vehicle with a six-degree-of-freedom manipulator. Supportive design studies included collection and analysis of production, manual functions, and injury data on the underground bituminous coal mining industry. Transfer tasks in section storage and working places were the prime candidates for mechanical handling. Functional specifications were developed for two handling devices (one to handle existing unit loads and one to handle repackaged unit loads) and for a vehicle to mount the handling device. Design concepts for nine different handling devices were developed and a cost/benefit evaluation made for each. Detail design, capital and operating costs, and method improvement savings data were developed for two battery-operated vehicles and for two different manipulators. The three-wheel vehicle with anthropomorphic manipulator was chosen for development.

Jan 1, 1978

By W. A. Wood, H. M. Bendler

Cylindrical fatigue specimens of OFHC* copper were subjected to alternating torsion while under axial tension. The superimposed tension strongly influenced the fatigue life of the specimens as well as causing characteristic changes in the structure of the fissures that form and develop throughout the life of the specimen. A further effect of the superimposed tension is a continuous extension of the specimen throughout its life in a manner formally similar to creep at elevated temperatures. RECENTLY, studies of the structural changes leading to fracture of metals by fatigue have been made by a technique which reveals, in section, the lattice distortion arising from slip movements inside the metal and the disturbances built up by these slip movements at the metal surface.1'2 According to this approach, fatigue develops as follows: a) fine slip movements concentrate in bands, producing little strain-hardening and thus permitting abnormal totals of plastic strain before fracture and, therefore, abnormal amounts of lattice distortion along each slip band; b) both forward and backward slip movements occur in each band which, according to their distribution across the band, may build up surface disturbances that include sharp notches; c) these notches early in the life of a specimen penetrate the distorted slip zones and transform them into deep, fine fissures; d) the fissures on continued cycling locally saturate the metal and cause local collapse in the form of a microcrack. Thus, the significant consequence of fatigue or cyclic

Jan 1, 1962

Laboratory experiments show that the delay detonators, either electric (copper coated or aluminium) or non-electric (down-the-hole) as generally used in opencast mines and quarries have some scattering from the actual firing time due to manufacturing inaccuracy and variations in basic ingredients of the product. This scattering varies from 1 to 4 % depending on the product quality. Due to this component scatter, adverse blasting effects like misfires, overbreak, underbreak or fly-rock may occur if the design patterns are not judiciously made. It has also direct impact on muck profile and fragmentation.

Jan 1, 1999

By Eric E. Cather

Approximately 270,000 cu yd (20[0],000 cu m) of inferred subeconomic auriferous gravel resources were estimated in three Tertiary deposits in the Polk Springs study area (fig. 1 and table 1). These resources are exposed between tuff-breccia and lava flows of the Pliocene Tuscan Formation and Paleozoic or Mesozoic metamorphic rocks which suggests that although no deposits were identified in the other RARE II areas, they may be concealed beneath the Tuscan Formation. Difficulty in choosing drilling targets will make the likelihood of resource discoveries small. The development and production of these deposits would also be prohibitive under current economic conditions due to the thick covering of volcanic rocks. Recent stream gravels of Deer Creek in the Polk Springs study area contain enough gold to attract gold hobbyists; however, the stream gravels do not have sufficient volume to be considered a resource. Potential exists for additional auriferous gravels near the Occidental Mine in the Polk Springs RARE II area.

Jan 1, 1983

Grey River Gold Mining Limited (GRGML) has constructed and largely completed the commissioning of an alluvial gold dredge designed to recover gold from a low grade gold deposit in the Grey River Valley, New Zealand. The most important resource that GRGML has are the people who are employed by the organisation. The low grade of the deposit necessitates the requirement to operate the dredge at optimum efficiency, which in turn requires the work force to be of high calibre and continually motivated. The primary prerequisite for employment at GRGML is for employees to be receptive to new ideas and have the adaptability to develop new skills and apply those skills to the changing demands of the workplace.   A continually changing organisational structure is utilised to meet the needs of a changing work environment. The adoption of an innovative site employment agreement allowing for flexible working hours has aided the achievement of good employee productivity and attendance.   Employees gain a higher quality of life by working a roster pattern involving twelve hour shifts and a four day on, four day off pattern.   Employees and management are communicating very well and working together to achieve organisational goals which will ultimately benefit the employees, the shareholders, the local community and the mining industry generally.

Jan 1, 1989

By C Spandler, S W. Richards G Rosenbaum, R J. Holm

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.The recent and active magmatic arcs of eastern Papua New Guinea (PNG) and the Solomon Islands are well endowed with sulfide mineralisation and include deposits such as Ladolam, Panguna and Solwara 1. The majority of the mineral systems in this belt are younger than four million years old, with some deposits remaining active to the present day as exemplified by active hydrothermal systems on the island of Lihir. The geodynamic setting that led to the formation of these deposits is still unresolved, with, for example, both the Pacific and Solomon Sea plates considered responsible for the formation of the Ladolam deposit on the island of Lihir under different models. In order to understand and characterise the formation of south-west Pacific mineral deposits, we must first reconstruct the complex geodynamic evolution of the region. New kinematic reconstructions show that while mineral systems in eastern PNG and the Solomon Islands are hosted within a single arc related to subduction at the New Britain and San Cristobal trenches, variable and discrete geodynamic settings exist within both the upper and lower plates throughout this region, which give rise to distinct mineralised corridors. Most notably, this region is host to: the Solwara 1 deposit, which occurs within a major transtensional corridor in the eastern Bismarck Sea the Ladolam deposit (Lihir), which is interpreted to have formed above but in relation to tearing of the subducting slab the Panguna deposit, which is related to structure in the subducting slab marginal to the actively spreading Woodlark Basin.An evaluation of the nature and variability of these diverse geodynamic settings through time can provide us with a better understanding of the relationship between the active south-west Pacific magmatic arcs and mineral deposit formation. It may also provide insights into the diverse array of deposit settings at ancient convergent margins, with applications in mineral prospectivity studies.CITATION:Holm, R J, Richards, S W, Rosenbaum, G and Spandler, C, 2015. Disparate tectonic settings for mineralisation in an active arc, eastern Papua New Guinea and the Solomon Islands, in Proceedings PACRIM 2015 Congress, pp 165–170 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

Two outstanding features of the world's young orogenic belts are their very consistently developed suites of volcanic rocks and, it is now recognized, the rather distinctive types of mineralization they contain. Further,it is now known that these volcanic suites exhibit evolutionary patterns, and it is beginning to appear that this evolution in style of igneous activity is accompanied by a parallel evolution in style of mineralization. Specifically,podiform chromite and stratiform pyritic copper ores of Alpine ultramafic/submarine tholeiite association progressively give way to more zincian stratiform ores associated with andesites and dacites, "porphyry copper"deposits developed in quartz dioritic to dacitic plugs, and lead-zinc stratiform ores related to increasingly pyroclastic, rbyodacitic volcanism.This "coupling" is exhibited well in the volcanic arcs - the young orogenic zones-of the SW Pacific which, with tbeir abundance of youthful and commonly unmetamorphosed materials provide an opportunity for investigating, through a petrochemical approach, the possible significance of ores in the elucidation of mechanisms of lava formation. It is suggested as a working hypothesis that in the orogenic (voleanic arc) regime ores are associated with the cale-alkaline rocks because these cale-alkaline rocks are in part generated by exhalative loss, and the ores are among the manifestations of tbat loss.

Jan 1, 1978

In a gravity separation device, particle shape, size and density all play a role. The combination of these determines where each individual particle reports to in the viscous fluid, where particle crowding (solids to water ratio) also plays a role. To understand the performance of gravity separation devices in the heavy mineral industry, these particle characteristics need to be measured. There are various challenges in analysing particle density and particle size simultaneously for the purpose of quantifying gravity separator performance, not to mention particle shape. These analytical challenges include the high cost of high-density sink-float fractionation, toxicity of high-density sink-float media, inability of sink-float media to fractionate at densities greater than 4.0 g/cm3, and the time-intensive nature of these fractionations. The use of the detailed particle-by-particle output from Qemscan® particle mineral analyses (PMA) as a fast and cost-effective alternative is evaluated. The size and density outputs from the Qemscan® were employed to characterize the performance of a heavy mineral spiral concentrator as an example. Critical analytical requirements are to be addressed before the Qemscan® output data can be utilized. Keywords Gravity separator, performance, heavy minerals, Qemscan® particle mineral analysis

Jan 1, 2011

By Burton Scott

A device for detecting carbon monoxide at ppm levels is described which is based on the measurement of infrared absorption at 4.65 microns. The unique feature of the nondispersive infrared instrument is contained in the optical design which includes a confocal cavity, increasing the effective optical path length by a large factor, thus greatly reducing the required package size. The cavity has the effect of reducing the total amount of radiation passing to the detector, but at the same time increasing the percent attenuation observed when adding CO, by a factor called gain. The radiation is chopped by a filter wheel which contains narrow band filters at 4.0 and 4.65 microns. The resultant signal produced by the pyroelectric detector is demodulated by the electronics to product an automatic gain control signal, proportional to the total radiation, and a difference signal, proportional to the CO present. Tests of a breadboard model are described which show cavity gains of 10 with noise levels equivalent to 2 to 10 ppm CO.

Jan 1, 1975

By Fun-Den Wang

Rock bolting has become a major method of coal mine roof support because of its effectiveness, economy, and convenience. The polymeric-resin-bonded bolt has generally proved to be more effective than the mechanically anchored bolt, but the higher cost of the resin bolt limits it to applications where the increased support is essential. The low-cost high-early-strength cement grout developed during this project will encourage more widespread use of fully grouted roof bolts provided practical installation techniques can be developed. Laboratory tests of four types were performed on various rapid-set and accelerated cement products to find a material with properties suitable for replacing resins. A proprietary gypsum cement was ultimately used with good success. A field test of the cement grout was made in an operating coal mine. An intersection was bolted in the standard pattern with cement-grouted bolts and instrumented. A nearby resin-grouted intersection was also instrumented and observations were carried out in both intersections for 2 months. No substantial difference was found between the support provided by the cement and the resin.

Jan 1, 1976

By Rajni Patel, John McDonald, Steve Dubnewych, Michael McKenna

The Upper Reach segment of the Northeast Interceptor Sewer (NEIS) is a3.2-km-long tunnel excavated in interbedded marine sedimentary deposits with approximately 40 m of cover. The tunnel was initially classified by Cal/OSHA as “potentially gassy.” During excavation, high levels of hydrogen sulfide and methane were encountered, prompting Cal/OSHA to reclassify the tunnel as “gassy.” In addition, the tunnel excavation encountered an abandoned, 100-year-old water tunnel known as the “Narrows Gallery.” This existing tunnel was completely full of water and under 30 m of hydrostatic head. This paper will discuss the unanticipated difficulties and design solutions implemented to construct a gassy tunnel exposed to high volumes of water.

Jan 1, 2005