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The Ngakuru zeolites are located about 20 km south of Rotorua and comprise a number of deposits dispersed along several fault lines. Relatively recent volcanic activity (250,000 years ago) resulted in ash depositions that vary in depth and mineralogy. Subsequent variable thermal alteration intensities generated predominantly clinoptilolite and mordenite zeolites with a range of physical characteristics. Typically the zeolites have low density (650 kg/m3), have high liquid (60% of dry weight) and odour absorption characteristics, and a high affinity for soluble cations (CEC =: 100 meq/100 g). Traditional kitty litter and oil absorbency markets are being expanded. New opportunities in waste and potable water treatment, organic and synthetic slow release fertilisers, use as a light weight aggregate for speciality concretes, and pozzalome activity are currently being researched.

Jan 1, 2000

By Jay C. Hanson

Various electrical and electromagnetic (EM) geophysical techniques are currently being evaluated by the U.S. Bureau of Mines for their effectiveness in the detection and monitoring of electrically conductive (1 to 5 S/m) lixiviant (leach solution) to depths of 600 m, either above or below the water table. These techniques include magnetotellurics (MT) , controlled source audiofrequency magnetotellurics (CSAMT), resistivity and focused resistivity, ground-penetrating radar (GPR), frequency-domain electromagnetics (FEM), and time-domain electromagnetics (TEM). Of these techniques, TEM may be the most effective, but CSAMT and focused resistivity also hold promise. Geophysical computer modeling of the borehole TEM technique was conducted based on an idealized geoelectric section (layered earth) with characteristics based on the Santa Cruz porphyry copper deposit near Cas a Grande, AZ. Layer resistivities and thicknesses were obtained from geophysical data and geologic logs available from the site. Modeling of borehole TEM in both preleach and during leach situations was conducted. Simulating the TEM method using computer modeling proved to be encouraging since there were substantial differences between leached and nonleached responses. The modeling does not prove the effectiveness of TEM in the field, but does indicate that detection of deep lixiviant zones is theoretically possible.

Jan 1, 1992

By Mark S. Sanders

This report presents recommended visibility requirements for continuous miner, shuttle car and scoop operations and details the methodology used to generate them. A task analytic approach was used to define information requirements and visual features which served as sources of information. Information requirements were prioritized and the location of visual features determined. From this analysis, visual attention locations, containing one or more important visual features, were identified. A total of 71 locations-were identified for continuous miners, 54 for shuttle-cars and 54 for scoops. A procedure was developed for assessing whether operators in existing machines could be expected to see the visual attention locations. The procedure makes use of a Human Eye Reference Measurement Instrument (HERMI) designed for this project and an outside-in photographic procedure for documenting compliance with the recommendations. A sample of continuous miners, shuttle cars, and scoops were used to test the procedure. Results are presented in the report.

Jan 1, 1981

By A. B. Cecala

It has long been known that ventilation is a cost-effective method to lower respirable dust concentrations in all types of mining applications. The National Institute for Occupational Safety and Health has been working on a number of different research techniques that use ventilation as a critical component to lower respirable dust levels at surface and metal/nonmetal operations in the United States. This article presents five such research efforts. The first research area discusses how improving the ventilation flow patterns in an iron ore mill facility lowered respirable dust concentrations by 31 pct throughout the primary grinding area. The second research area examines how respirable dust levels were lowered at a dimensional stone shop by using air cleaning units suspended from the ceiling. A third area discusses how improvements in ventilation at underground limestone mines lowered respirable dust concentrations. The fourth area examines how improvements in dust filtration and pressurization systems significantly impacted the air quality in enclosed cabs of surface mining equipment. The last area presents a newly developed clothes cleaning technique. This technique uses an air spray manifold to blow dust from a worker?s clothing in an enclosed booth, which confines the dust for capture and removal by a baghouse dust collector. These research areas represent an array of different control technologies to lower respirable dust concentrations. Ventilation is an integral part of these control technologies.

Jan 1, 2006

By D. F. Malan

This paper gives an overview of the difficulties associated with determining the strength of hard-rock pillars. Although a number of pillar design tools are available, pillar collapses still occur. Recent examples of large-scale pillar collapses in South Africa suggest that these were caused by weak partings that traversed the pillars. Currently two different methods are used to determine the strength of pillars, namely, empirical equations derived from back analyses of failed and stable cases, and numerical modelling tools using appropriate failure criteria. The paper illustrates that both techniques have their limitations and additional work is required to obtain a better understanding of pillar strength. Empirical methods based on observations of pillar behaviour in a given geotechnical setting are popular and easy to use, but care should be exercised that the results are not inappropriately extrapolated beyond the environment in which they are established. An example is the Hedley and Grant formula (derived for the Canadian uranium mines), which has been used for many years in the South African platinum and chrome mines (albeit with some adaptation of the K-value). Very few collapses have been reported in South Africa for layouts designed using this formula, suggesting that in some cases it might yield estimates of pillar strength that are too conservative. As an alternative, some engineers strongly advocate the use of numerical techniques to determine pillar strength. A close examination unfortunately reveals that these techniques also rely on many assumptions. An area where numerical modelling is invaluable, however, is in determining pillar stresses accurately and for studying specific pillar failure mechanisms, such as the influence of weak partings on pillar strength. In conclusion, it appears that neither empirical techniques nor numerical modelling can be used solely to provide a solid basis for conducting pillar design. It is therefore recommended that both these techniques should be utilized to obtain the best possible insight into a given design problem. Owing to the uncertainties regarding pillar strength and loading stiffness, monitoring in trial mining sections and in established mining areas is also an essential tool to test the stability of pillar layouts in particular geotechnical areas.

Jan 1, 2011

By Susheel R. Kolwalkar

A significant increase in the side shear capacity over a period of time is often observed in case of driven piles. This phenomenon is referred to as ?setup? or ?freeze?. This phenomenon cannot be predicted based on the knowledge of the engineering properties of soil. Different kinds of mechanisms have been proposed in order to explain set-up in cohesive soils. In engineering practice, set-up is incorporated in design on the basis of empirical formulae and depends to a large extent on personal experience and judgment of the design engineer. Set-up is a natural process which cannot be accelerated by any existing practice. A research was initiated to investigate the mechanism of pile set-up in clayey soils and explore the possibility of accelerating the set-up process by an electro-kinetic method. The system chosen for the present study consists of a prototype steel pile driven in kaolinite clay. A laboratory test program was developed at Cleveland State University in order to meet the goals of the proposed research. Results obtained from these tests are very encouraging and show pile capacity increase of 200% within the first 5 days of electric gradient application versus those that experience natural set-up. In this paper, theoretical considerations and laboratory test results are presented and discussed.

Jan 1, 2008

By P Storey, B Deans, T Lancaster

Straits completed its Feasibility study on the Whim Creek Copper Project in 1996. At this stage WCCP provided Straits with an open pit mine - heap leach - SX-EW copper project to follow on from its successful Girilambone Copper Operation (GCC). Since this time Straits has continued to review WCCP investigating a number of development and production scenarios. The development of Whim Creek, early 2004 and is on schedule to commence copper production in the final quarter of 2004. On current reserves Whim Creek will produce approximately 17 000 tonnes of copper cathode per annum for three to four years, at cash costs of The paper will cover a general description of the project, the project development and key design issues. Additional construction related issues associated with the complete relocation of the GCC plant to Whim Creek will be covered in the conference presentation.

Jan 1, 2004

By Aly M. Mohammad

State and federal agencies during rehabilitation of existing bridges may require the existing bridges to be evaluated under seismic conditions. If the bridge does not perform under the seismic event, the bridge may require seismic retrofitting. Bridges are classified as: Critical, Essential, and Others according to their importance. Geotechnical considerations play a major role in evaluating the bridge behavior under a seismic event. Subsurface conditions influence the magnitude of ground acceleration and hence the forces and moments on the superstructure. This paper will provide a detailed description of the geotechnical aspects associated with the seismic retrofit evaluation for the 12th Street and 14th Street Viaducts located in Jersey City, New Jersey. The paper will also present a description of the geotechnical investigation program including seismic cross-hole surveys to determine the dynamic soil parameters, including the results of site-specific response spectra for both the 475 and 2475-year events. Liquefaction assessment methodology utilizing an equivalent factor of safety will also be described and the design method used will be summarized. In general, the pile foundation is modeled as 6x6 foundation stiffness matrix with 36 stiffness coefficients at the center of the pile cap. The seismic loading on the foundation is evaluated in a pseudo-static analysis, where the dynamic earthquake-induced loads are presented by static forces and moments. The computer program FB Pier was used to evaluate the foundation stiffness. The moments, axial loads, and shear are input into the FB Pier model. The stiffness of the foundation is determined and the results are then input into the Structural model to determine new forces and displacements. Adjustments are made until the loads are compatible with the stiffness used. The understanding of the geotechnical conditions at the 12th Street and 14th Street Viaducts and the coordination between the Bridge and Geotechnical Engineers were able to provide significant cost saving to the Owner. The Design Engineers were able to retrofit the existing Viaduct foundations with reasonable number of additional piles. It is believed that the results and finding presented in this paper will benefit both the Bridge Engineers and Geotechnical Engineers by highlighting the importance of interaction between the two disciplines.

Jan 1, 2006

A large lab apparatus was designed using a scale-down methodology based on the design legacy of the current FLSmidth commercial forced air flotation machines. This new apparatus, along with a new test methodology, was used to evaluate new rapid prototype concepts. The apparatus was designed to monitor bubble size, power, pumping capacity, Jg, velocity profiles, froth character, and tip speed. The methodology developed follows a sequence that goes from hydrodynamic tests and solids suspension tests to a flotation kinetic test. This methodology has been demonstrated to be a good tool to determine the effect of machine design changes on flotation.

Jan 1, 2012

By C. G. Storm

Permissible explosives are those that have passed the tests pre- scribed by the Bureau of Mines for explosives intended for use in coal mines, and are therefore recommended by the bureau as suitable for this class of work when used under the prescribed conditions. The tests for permissible explosives and the conditions prescribed for their use are described in Miners' Circular 6 of the Bureau of Mines. Up to June 1, 1915, 168 explosives had been classed as per- missible explosives; 133 of them were then on the bureau's "per- missible list" and 35 had been withdrawn by the manufacturers. In addition to the required physical tests, each explosive is sub- jected to a complete chemical examination in order that its exact composition may be known and also that the composition of future samples of the same explosive collected in the field may be compared with that of the sample which originally passed the bureau's tests, for by such comparison it may be possible to ascertain whether or not the explosive as supplied to the miner is still "permissible." This bulletin is published primarily for the purpose of informing manufacturers of such explosives as to the methods used by the Bureau of Mines in the analysis of samples received for tests to determine their permissibility. Such information may be of value in cases of possible controversy over the results obtained in the analysis of a field sample as compared with those obtained in ana- lyzing the sample originally tested by the bureau. Also, a descrip- tion of the methods used by the Bureau of Mines in the analysis of explosives should be of assistance to the many chemists engaged in similar analytical work.

Jan 1, 1916

By Trevor Rangasamy

Technically based guidelines for managing rock related risks associated with strip mines in South African collieries are currently vague and are to a large extent based on experience and trial and error. To date, no mine specific or universal design charts exist within the South African industry. Quantification is done on a reactive basis i.e. following reported instabilities. The conditions under which, proactive tools to manage instabilities would be practically applicable are: The design of simple easy to use charts. Designing the charts for a target audience that is primarily production management. Well organized, logical set-up of the charts that will allow for easy future refinements. Allowing for variations in rock and soil properties within the charts that would account for colliery specific and region specific variability. The factors selected for in depth investigation that were deemed to have either individually or in combination, a primary influence on the stability of strip mines are (in no order of priority): Appropriate batter angles for ?soft? materials. Surcharge loading (spoils, dumps, topographical highs) on the highwall side. Influence of the thickness of stratification on stability. Influence of moisture content on stability. Influence of the changes to the coal seam dip angle on stability. Influence of persistent ?strip long axis? parallel faults/joints on stability. Spoil stability for variations in material type. This paper provides details of the work undertaken, using principally numerical modelling techniques, to produce design charts that will allow for proactive management of rock-related instabilities on strip mines.

Jan 1, 2008

By Friedel. Michael J.

The U.S. Bureau of Mines investigated acoustic emission (AE) and the Kaiser effect in six types of rock: St. Cloud gray granodiorite, Barre granite, Dresser basalt, Salem limestone, Berea sandstone, and a volcanic tuff. AE signatures were used for interpreting the rock deformation stage and for indicating mechanisms of failure in uniaxial compression. The research demonstrated the advantages of using the volumetric stress-strain curve, as opposed to the more conventional uniaxial curve, for correlating AE response signatures with deformation stages and fracture processes in the rock. Standardized experimental procedures were used for the AE monitoring. The Kaiser effect was shown to be capable of determining prestress levels to within a few percentage points in uniaxial compression tests. Also, prestress memory was shown to be retained in the rock for periods of up to at least. 5 months, the maximum period of testing. The Kaiser effect AE technology holds promise for providing a comparatively inexpensive and less complex method for examihing stress history in rock. However, since the conftning stress has a pronounced influence on the Kaiser effect, it must be considered in developing technology for determining peak fteld stresses based on the Kaiser effect.

Jan 1, 1990

By R. L. Brown

The Buchans mining district is located roughly at the center of the island of Newfoundland and contains some 18 separate mineral deposits. The first of these deposits was discovered in 1905, the latest discovery having been made in 1979. To the present (1983), some 16 Mt (17.7 million st) grading 1.33% Cu, 7.5% Pb, 14.5% Zn, 115 g/ t (3.7 oz per ton) Ag, and 1.4 g/t (0.04 oz per ton) Au have been mined. Mining operations are now largely terminated, but a few hundred thousand tons of economically marginal reserves may be mined in a salvage operation. The Geological Association of Canada Special Paper No. 22, "The Buchans Orebodies, 50 years of Mining and Exploration," contains papers which describe the history, geology, and the application of evolving geological concepts in exploration. Papers by Neary, Swanson, and Thurlow and Swanson in that volume are topical to the present discussion. Successful exploration techniques at Buchans included physical prospecting, utilization of the state-of-the-art geophysical techniques, saturation diamond drilling which was made possible by the high gross value of the existing ore, and, since 1955, diamond drilling directed by fairly well understood geological parameters. The record of discovery started in 1905 when the Buchans River deposit was found by Matty Mitchell, a prospector employed by the Anglo- Newfoundland Development Co., a British company which owned mineral rights over a very large area in the Red Indian Lake-Exploits River drainage system.

Jan 1, 1991

By L. Ross Weber

Gentlemen and guests of the Rocky Mountain Coal Mining Institute: This is the thirty-second regular meeting of our Institute, and rather than try to make some extemporaneous remarks, I thought it best to write them out, so I could in that way give them to you, and probably give you a new thought for the future conduct of our Institute. The thirty-first regular meeting of the Rocky Mountain Coal Mining Institute was held in Salt Lake City, June 22, 23, and 24, 1932, and due to rapidly changing conditions in the coal industry, subsequent meetings have been postponed from time to time, as many of our members and our Secretary have been tied up with code and labor matters. Since our last meeting, at which was discussed problems of vital interest to all of us, especially the production and marketing of coal safely and economically, and the stabilization of our industry, which has already suffered two years of deplorable conditions, almost two more years have been added to the record, but during the past six months miracles have happened, and an industry which formerly was unable to govern itself, has now, through the aid of our Government, at least learned how to make a proper start in that direction. Whether we like it or not, and whether or not the things being done are in agreement with our various political beliefs, without doubt, we are in a much better position today than prior to this transformation. However, it is a pleasure to all of us to note that safety has not been lost sight of in the interim, and without doubt, as later papers and statistics will substantiate, the period since our last regular meeting has probably shown the most remarkable safety achievement of any period in recent history.

Jan 1, 1934

By R. F. Randolph, R. S. Fowkes, J. J. McClelland, G. H. Schnakenberg

Between 1986 and 1992, there were268 deaths and 54,642 severe injuries to workers in underground U. S. mining operations. Clearly, this level of health and safety risk is not acceptable. While most underground coal mining jobs are dangerous, some are much more dangerous than others. Many jobs in an underground coal mine are clustered around the working face—the place where machinery digs coal from the surrounding rock. The hazards in this area are numerous: When the coal is removed, the ground around it becomes unstable and can cave in on the workers. The mining machines used there are large, heavy, powerful, and move in many different directions in a very confined space, presenting danger to workers. Also, the machines churn up coal dust that causes black lung and other ailments. Figure1 shows a modern radio remote controlled continuous mining machine and its operator. In a typical mine, the jobs with the greatest exposure to hazards involve operation of machinery that cuts tunnel-like passages into the coal (the continuous mining machine) and machines that insert supportive steel bolts into the rock above the work area (roof bolting machines). The workers who endure these hazards are at almost twice the risk of death or disabling injury than co-workers in other safer areas of the mine. Of the statistics quoted above, 106 of the 268 deaths and 21,552 of the 54,642 severe injuries occurred in jobs involving equipment at the working face. The operators of roof bolting and continuous mining machines account for only 21% of the work force but suffered 40% of the deaths and 39% of the lost-time injuries during1986-1992. These death and injury rates are almost twice the rate for workers in other underground mining jobs (see figure 2). The estimated total cost of the 106 fatalities and21,552 lost-time injuries was $327 million from 1986-1992. On average, each fatality cost over $1 million and each lost-time injury costs in excess of $9,000.

Jan 1, 1994

By G. Stecklein

This report summarizes the results of research into the areas of the fragmentation and entrainment of Airborne Respirable Dust (ARD). The objectives of this program were four-fold: first, to review the present state of knowledge regarding ARD; second, to expand this state of knowledge through the identification of hypothetical microscopic mechanisms by which the coal is fragmented and the dust becomes entrained; third, to specify the informational requirements to verify or nullify these hypotheses; and fourth, to relate experimental techniques that will produce that required information. Additionally, insights are provided regarding potential methods of extraction and/or treatment which may reduce the concentration of ARD.

Jan 1, 1982

By S. Vorberg, J. Preussner, B. Fischer, U. Glatzel, R. Völkl, M. Wenderoth

Pt-Al-X alloys have shown good mechanical properties and adequate oxidation resistance. Starting from a promising Pt-Al-Cr alloy, the influence of Ni additions was investigated. After ageing finely dispersed precipitates are observed. Nb, Ta, Ti and Re increase strength when added as partial substitute for Al. Minor additions of B increase creep resistance and rupture time remarkably, owing to strengthening of the grain boundaries. The evolution of the alloy development programme as well as selected properties of the multi-component Pt-base alloys are presented.

Jan 1, 2006

By J. R. Hamke

THE WILLISTON basin is the largest known sedimentary basin on the North. American continent. Two-thirds of this large basin lies within the United States in Montana, North Dakota, and South Dakota. Less than 10 years after the first commercial oil discovery in North Dakota in 1951, the petroleum became one of the largest industries in the three-state area. Crude petroleum is now the most valuable mineral resource in the area. In 1960, the basin produced 39 million barrels of worth $100 million at the wellhead. Most of the 137 oil pools covered to date are in Paleozoic carbonates at depths ranging from 3,000 to 13,000 feet. The major producing fields, centered on the Cedar Creek anticline in Montana and the Nesson anticline in North Dakota, produce from depths below 6,000 feet. This report presents descriptions of all phases of the Williston basin petroleum industry, including leasing, exploration, geology, drilling, production, transportation, and refining. Engineering, physical, and production data, maps, and crude petroleum analyses for 137 separate oil pools are included.

Jan 1, 1966

Auger operations produced 14 million tons of coal in 1974, or approximately 5% of all surface mined coal. It was the most efficient of all coal mining methods, producing 40.0 tons per man-day. Exhibit 1.1 gives a breakdown of productivity of all coal mining methods. Exhibit 161 PRODUCTIVITY OF COAL MINING METHODS (Short tons per man-day) [Method - 1971 1972 1973 1974 Conventional 11.00 10.00 9.75 9.30 Continuous 13.00 12.50 12.25 11.90 Strip Mines 35.69 35.95 36.00 36.00 Auger Mines 39.00 43.00 45.33 40.00 ] Unlike other surface mining methods, augering produces clean coal, largely uncontaminated by foreign materials, other than those existing in the coal seam itself. However, compared to other methods, the coal recovery rate is relatively low. For example, a triple-headed auger in a 35-inch seam would recover approximately 50% of the coal in the seam as compared to a 90 to 95% recovery rate for strip mining and a 55 to 65% recovery rate for deep-mining. The low auger recovery rate is due to the circular cuts and pillars left in the seam.

Jan 1, 1975

By Joseph A. Sutton

This study was undertaken by the Bureau of Mines to determine whether the sulfur-oxidizing bacterium Thiobacillus thiooxidans could use sulfur compounds to produce sulfuric acid in sufficient quantities to leach valuable metals from low-grade ores. The results of extended tests indicated that the bacterium is capable of extracting appreciable amounts of copper and cobalt from ore and mineral samples when sulfur is available in a state that can be readily assimilated by the organisms. Under the conditions of these tests, this organism was not able to assimilate and oxidize the sulfur as it occurred in the ores and minerals. Ores containing copper minerals in the silicate, carbonate, and oxide forms, in the presence of elemental sulfur, were more susceptible to bacterial action than ores containing copper minerals in the sulfide form. Thiobacillus thiooxidans remained active on elemental sulfur in the presence of some of the ores which were tested, but could not tolerate others. Therefore, strains of the bacterium were progressively adjusted to increasing concentrations (0.5 to 10 grams) of the individual ores until they could remain active on 10-gram portions of all ores being tested.

Jan 1, 1961