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By Cortes JP

In a dynamic environment such as the Star Mountains of Papua New Guinea Geotechnical Engineering for the Ok Tedi Project must be described as both interesting and challenging. To be effective a reasonable sized team of dedicated people is required with occasional supplementation by specialist consultants and an annual review process. Ok Tedi Mining Limited's (OTML) Geotechnical Section has a vision to be recognised as the leading mine-based geotechnical engineering section in PNG and to be world class by any international standards. This paper deals with the organisational and operational duties of the Geotechnical Section at the Ok Tedi Mine. One of our major roles is in the area of safety, and in particular in the early warning of natural and mining induced geological hazards that may affect safety and/or productivity. The major activities in- clude geotechnical inspections (pit, waste dumps, tunnels, re- gional), data collection activities and database management, geotechnical design and control work.

Jan 1, 1997

By I Wilkomirsky, F. Parada, R. Parra, E. Balladares

"The neutral roasting of As bearing copper concentrates is confirmed well established and promising option for the treatment of this type of complex concentrate. The AS elimination by volatilization allows subsequent treatment of the calcines produced in a conventional pyrometallurgical process, by blending this product with standard concentrates.Several tests were performed using the fluidized bed pilot plant at the University of Concepción with different types of concentrates. Calcines, fines from two hot cyclones and flue dust from the ESP were collected. These materials were characterized using QEMSCAN® and the results used for the development of a mass and energy balance which took into consideration the specific chemical transformations that occurred in the reactor.A physico-chemical/kinetic model is proposed to explain the formation of bornite, chalcopyrite and magnetite. The mechanism involves solid-gas reactions between chalcocite, pyrrhotite and gaseous sulfur that without the mineralogical characterization would not have been possible to propose"

Jan 1, 2014

By William D. Gallant

This paper describes a joint cooperative project between the CANMET Cape Breton Coal Research Laboratory and the Cape Breton Development Corporation to conduct a trial of split set cable slings for remedial support in longwall gateroads. Slings were installed in two test sections of the 2 West panel, Phalen Mine which exhibited deformation and the potential for excessive deterioration when subjected to the front abutment of the wallface. Roadway support behaviour was monitored at the trial sites, including lengths of roadway with the standard support of steel sets without remedial support. Observations were made on convergence, loading of the steel supports, loading of the slings, and wallface performance. Comparisons are made of the results obtained from the areas with remedial support to that without, which demonstrates that the slings provided effective remedial support limiting further deterioration of the roof. Improved face end conditions have contributed to increases in safety and productivity of the longwall panel.

Jan 1, 1990

By Jensen B, Ofori P, He Y, White E, Stanmore B, Brien M, O&apos

As part of a large AMIRA project, an on-line moisture meter was installed at two mine sites in Central Queensland. This project investigated the factors which control the moisture content of coarse (>0.5 mm) coal from the centrifuges used in conventional coal preparation plants. It was placed immediately after the first centrifuge to isolate the factors pertaining to one machine and its feed.The meter was found to be accurate and precise when compared with manual and mechanical sampling methods. The Grubbs estimator technique indicated that its precision is better than 0.3 per cent at the 95 per cent confidence limit.It has been identified that:1. the variability of the measured moisture contents of coarse coal can be described by normal distributions. Standard deviations of about 0.6 per cent are common; and2. the treatment of the coarse coal on the drain and rinse screens immediately prior to the centrifuge can affect the final moisture content.

Jan 1, 1995

By Thomas L. Vandergrift

The type and severity of coal mine entry failures are affected by the strength and stiffness properties of the roof, floor, end coal. Knowledge of the mine-wide trends of these properties Is valuable in developing effective ground control plans. Within the context of a larger effort to Improve entry stability In high horizontal stress fields, the U.S. Department of the Interior, Bureau of Mines, has evaluated three portable, on-site test devices to determine their suitability for identifying mine-wide physical property trends. The devices evaluated were the borehole shear tester, the Schmidt harmer, and the point load tester. Despite the lack of standardized data Interpretation procedures, each device provided useful on-site physical property data. The Schmidt homer was preferred for trend identification because of Its speed and simplicity. Schmidt hammer data were collected over a large area of an underground coal mine to compare calculated roof strength trends with a known geologic feature.

Jan 1, 1990

By Milawarma E, Cusack C

The Sapan Dalam coal deposit of Indonesia consists of ten steeply dipping seams with thicknesses varying between 0.1 and 3.5 m and split by shale, clay, silt and sandstone. The area contains four faults dipping about 75¦ with four to 85 m vertical displacements. The complex nature of the deposit coupled with limited 27 exploration drillholes at an average spacing of 200 m made it difficult to create a realistic geological model. A three-dimensional gridded seam model gave a fair representation of the deposit. Attempt to create an optimum pit using the WHITTLE 3D pit optimiser proved unsuccessful since the pit optimiser is restricted to standard regular or fixed blocks. The gridded seam model was converted to a fixed block model prior to the optimum pit design. Smoothing and pit base controlling were also introduced to obtain a smoother pit. A mining scenario produced 3.6 million tonnes of coal, 28.4 million bcm of waste and US$18.1 million revenue.

Jan 1, 1995

By Stewart WJ

Australia's first offshsore well was spudded in on 27th December 1964 and resulted in the discovery of the Barracouta gas field. Further exploratory drilling led to the discovery of the Marlin gas field in December 1965, the Kingfish oil field in April 1967 and the Hblibut oil field in June. 1967. In September 1968, a small oil reservoir was found in a sand below the main Barracouta'gas reservoir. The Snapper gas field was discovered in May, 1968 Information on exploration activities associated with the discovery of oil and gas in the Bass Strait area may be found in the paper, "Exploration in the Gippsland, Bass and Otway Basins, Australia" by B. M. Hopkins. _ Development of the commercial fields is being undertaken on an equal participation basis by Hematite Petroleum Pty. Ltd. and Esso Exploration and Production Australia Inc. Esso Standard Oil (Australia) Ltd. is responsible for the design, construction and operation of the production facilities.

Jan 1, 1970

Answers to many questions arising in the different phases of exploration, estimation and production of a mineral deposit, can be found in the geostatistical theory of G. Matheron. It is shown that all these questions regarding sample size, number of samples, shape of drilling pattern can be answered as soon as the continuity of the mineralization is quantitatively characterized by means of a variogram. Next a formula which gives the variance of the error associated to any estimation procedure (i.e., any method and any sampling pattern) is given. Applications to the computation of the standard error of the'mean for various sampling patterns are shown, as well as how to use the formula to simulate several possible sampling strategies and choose the best one. Altogether it is shown how to answer the often heard question, "what happens if such and such sampling procedure is used?", rather than giving an hypothetical "optimal" solution.

Jan 1, 1976

By Bryan F. Ulrich

If resin-grouted roof bolts are not installed correctly, mine roof reinforcement can be affected, and roof falls can result. A bolt installation variable that is readily controlled by the mine operator is annulus thickness. The objective of this U. S. Bureau of Mines investigation was to study the effect of annulus thickness variations on the integrity of 3/4-in-diam resin-grouted bolts. Forged-head test bolts, 2 and 1 ft long, were installed in concrete blocks that had been drilled with 1-, 1-1/8-, 1-1/4-, 1-3/8-, and 1-1/2-in-diam bits. Standard pull tests were performed; then the concrete was broken away from the bolts so that grout mix quality could be inspected. It was found that the optimum annulus thickness is 1/8-in (l-in-diam drill hole), and as annulus thickness increases from the optimum, there is a corresponding decrease in grout mix quality, effective grout ratio, and axial stiffness.

Jan 1, 1989

By Jonathan P. Furniss

The paper describes a range of laboratory tests undertaken on full column resin anchored glass fibre rockbolt systems, to assess all aspects of their performance. Laboratory instrumentation has been developed for the accurate study of strain transferral from the Glass Fibre Reinforced Plastic (GRF') bolt, through the surrounding resin annulus, and into the rock. Experience in laboratory testing to the new British Standard on glass fibre rockbolting is discussed. A critical comparison is made of the influencing parameters affecting . underground rockbolted roadway performance to the parameters assessed by BS 7861 : Part 1 The work has been co-funded by MA1 Systems UK Ltd. who supply GRP rockbolt components to the British coal mining industry, mainly for the reinforcement of coal ribsides. In rockbolting, glass fibre has a number of useful * qualities which are discussed in the paper. These properties, make the product more suitable than steel in certain applications, both in mines, and other engineering structures such as tunnels, soil stabilisation, and coastal defences.

Jan 1, 1997

By Kenneth C. Stewart

This contract was directed toward a study of the attenuating properties of earmuffs as worn by miners. Two attenuation measurement procedures were utilized. Human subjects were tested in a diffuse sound field according to threshold shift procedures recommended by the American National Standards Institute and a physical measurement procedure was accomplished in the same diffuse field on the same human subjects with microphones placed simultaneously on the inside and outside of the muffs. All measurements were obtained in one third octave of random noise. The results of the study indicated that physical and psychophysical attenuation measurements are in essential agreement at frequencies from 125 Hz to 2 KHz. Above 2 KHz the psychophysical measurement demonstrates larger amounts of attenuation than the physical measurement. The difference in attenuation ranged from approximately 7.0 dB to 9.0 dB at frequencies of 4 KHz and above. A possible explanation for the observed differences in attenuation has been presented.

Jan 1, 1980

By H. E. Powell

Because of increasing consumption of high-and super-duty refractories, the Bureau is studying the feasibility of beneficiating submarginal and marginal clays. Diverse mineral dressing tests were used to beneficiate samples from the east-central Missouri fire clay district. Standard ASTM tests were used to determine refractory properties of both crude and beneficiated clay samples. Marginal and submarginal clays containing impurities were effectively beneficiated by both wet-cyclone and wet-table treatment, but the wet-cyclone treatment was cheaper. Ion-exchange resins in the hydrogen form will probably prove more effective in removing potassium, the only alkali in Missouri fire clays to be a problem. Resins with greater cross linkage are more effective than resins with less. Roasting the crude clays before removing alkalis by chemical leaching was ineffective. By applying ultrasonic energy at a frequency of 10 to 25 kilocycles to aqueous suspensions of the clays, subsequent ion-exchange extraction of potassium was slightly improved. Higher frequency ranges did not help.

Jan 1, 1963

By Okabe K

Development in the theory and practice of hearth drainage is reviewed. Difficulties in the hearth drainage were re- newed during late sixties and early seventies when the size of a blast furnace and the top pressure were increased to result in the increase in tapping rate. Hearth drainage was improved first by in- creased number of tapping and then decreased tapping rate as it was predicted by theoretical studies. State of the coke bed in the hearth, e.g., 'floating' or 'sitting-on' the hearth bottom, is discussed in relation with influential factors on it and its influence on the furnace operation. The 'sitting-on' coke bed is to be aimed at for the consistent furnace working and for the lower rate of erosion of the hearth refractory. As the continuous tapping became standard prac- tice in large blast furnaces, the interest in the basic research renewed. Prospect of the further research including mathematical modelling of the hearth drainage is discussed.

Jan 1, 1981

The National Institute for Occupational Safety and Health (NIOSH) conducratory and field tests to evaluate the effectiveness of dust collector bags for reducing dust liberation and operator exposure from a roof bolter?s dust collection system. The laboratory tests evaluated the bag?s effectiveness to contain dust and the effect on canister filter loading in both a bag and bagless condition. The dust emissions from the collector?s exhaust were also measured in each condition during laboratory testing and show that nearly 100% of the test dust fed into the collector was captured by the dust bags. Loading and pressure drop on the dust collector?s canister filter is greatly decreased when using the bags, enabling longer periods of drilling without filter removal/cleaning. The field results showed that, even though dust standards were met, respirable dust in exhausted emissions was reduced around the bolter. Laboratory and field results show that benefits from use of the bags are realized in all areas of operator exposure.

Jan 1, 2008

By T. W. Beck

The National Institute for Occupational Safety and Health (NIOSH) conducratory and field tests to evaluate the effectiveness of dust collector bags for reducing dust liberation and operator exposure from a roof bolter’s dust collection system. The laboratory tests evaluated the bag’s effectiveness to contain dust and the effect on canister filter loading in both a bag and bagless condition. The dust emissions from the collector’s exhaust were also measured in each condition during laboratory testing and show that nearly 100% of the test dust fed into the collector was captured by the dust bags. Loading and pressure drop on the dust collector’s canister filter is greatly decreased when using the bags, enabling longer periods of drilling without filter removal/cleaning. The field results showed that, even though dust standards were met, respirable dust in exhausted emissions was reduced around the bolter. Laboratory and field results show that benefits from use of the bags are realized in all areas of operator exposure.

By Gary Raymond

The Similkameen Division of Newmont Mines Limited operates a low-grade open-pit copper mine in southern British Columbia. The copper mineralization is extremely erratic.As a result, over seven years of operation, ore control methods have evolved from standard flagging based on blast-hole assays, through an in-pit grab sampling system, to the present method of mining to computer-determined ore-waste boundaries based on geostatistics. These improved ore control methods have resulted in a gain of at least 25% on ore tonnage miffed, at the same grade as obtained using earlier techniques. At the same time, geostatistical ore reserve estimates are now within 7% of milled ore tonnage and grade on a yearly basis, whereas the original polygon ore reserves under-estimated mineable ore tonnage by 15% to 45% and over-estimated grade by about 20%. The author discusses why traditional ore estimation methods give poor results in erratically mineralized orebodies and describes the geostatistical approach to the problem.

Jan 1, 1979

By M. L. Odenbaugh

The viscosity reduction effect of varied concentrations of leonardite (a naturally oxidized form of lignite) and leonardite-caustic on the rheological properties of a standard bentonite drilling fluid was studied and evaluated. The minimum plastic viscosity was found to occur at application rates of 4 lb of leonardite and 1.33 lb of caustic per barrel of drilling fluid. Leonardite-caustic treatment was not beneficial in treatment of salt-contaminated drilling fluids. Although filter loss rate was reduced; both yield values and gel strength were increased. Compared with other viscosity control agents) including quebracho) ligno-sulfonate) humic acids extracted from leonardite) as well as other reaction products of lignite) leonardite is less effective at low application rates but is an effective treating agent at rates of 2 Ib/bbl or more. Considering the comparable merits of the substance tested) the major factor in determining which agent to use should be based on cost consideration.

Jan 1, 1967

By L. D. Tracy

The first study of this subject hits been made in Illinois, but as opportunity affords, similar studies will be made in other States. It is hoped that the data obtained will assist the coal-mining industry to standardize the forms of leases, and so avoid some of the abstruse and ambiguous clauses which slay be found in many of them and the consequent liability of costly litigation. In some of the publications of the Illinois Mining; Investigations prepared under a cooperative agreement with the U. S. Bureau of Mines, the Illinois State Geological Survey and the Engineering Experiment Station of the University of Illinois, the coal areas of the 'State have been divided into eight geological districts, each district being treated separately. This report covers District No. VI of that classification, and it is hopped that studies of the other districts will be completed in the near future and similar results published.

Jan 1, 1926

By E. D. Calvert

As part of its goal to minimize the requirements for critical and strategic minerals, the Bureau of Mines is conducting research to foster the use of domestically abundant materials such as molybdenum. This report describes the development of an investment shell molding technique that can be used to make castings of molybdenum and its alloys. The mold material is cubic Zr02 with a monoclinic Zr02 binder. The shell, formed by standard investment molding techniques described in the text, is prepared for molybdenum casting by firing for 6 hours at 1,550° C (2,822° F) or for 4 hours at 1,650° C (3,002° F). The resulting castings have predictable and reproducible dimensions with good detail. As-cast strength is poorer than the strength of wrought materials below 1,600° F. At and above this temperature, tensile strengths of cast and wrought materials are nearly equal. Aqueous corrosion of the castings in most media is insignificant.

Jan 1, 1982

By Murray Jacobson

Facts obtained by the Bureau of Mines on the dust-explosion hazard in air of materials used in the plastics industry are presented for 313 samples studied in the laboratory. Information is given on ignition temperature of dust clouds and layers, minimum explosive concentration, minimum energy required for ignition, explosion pressure and rates of pressure rise, amount of inert dust required to prevent ignition and flame propagation, and, in some instances, on the limiting oxygen concentration in an atmosphere to prevent ignition by spark and by heated surface. The effects of particle shape, additives, and resin structure on explosibility are discussed. Relative explosibility of the materials is related to the ignition sensitivity and explosion severity and is denoted by an empirical index. Recognition of the degree of hazard will facilitate adoption of adequate measures for preventing ignition and explosion during manufacturing or processing.

Jan 1, 1962