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By Yoneji Kanoh, Masahiko Ohtsuka

In Japanese tunneling history, it has commonly been accepted that the long-round driving is difficult due to the complicated geological condition. Therefore, the maximum past record has been less than 3 m per round. A new record of advance was established in the 99 m2 headrace tunnel of Imaichi Water Power Station Project with an advance of 239.5 m in a month by drilling 3.9 m deep blast holes. The geology of the headrace tunnel composed of pyroxine andesite (ie. 960-1770 kg/cm2, VP3.1-4.3 km/s) which had several clay seams and open cracks and was moderately weathered. Automatic shotcrete machine was used for shotcreting. Rock support was specified according to the N.A.T.M. with each different rock type. The contractor achieved a remarkable tunneling advance not earlier experienced in Japan.

Jan 1, 1983

ICMM’s vision is ‘a viable mining, minerals and metals industry that is widely recognised as essential for modern living and a key contributor to sustainable development’. The ICMM Sustainable Development Framework provides the basis for achieving this vision by assisting the industry to improve its performance. Two years on from the first SDIMI conference, significant progress has been made in further developing and implementing the Framework. To fulfill their commitment to implement and report performance against the ten sustainable development principles in the Framework, ICMM’s corporate members have committed to report ‘in accordance’ with the GRI 2002 Sustainability Reporting Guidelines and the Mining and Metals Sector Supplement, developed by the GRI and ICMM. While much remains to be done, development of the Supplement and the commitment to reporting mark an important milestone for ICMM and the sector.

Jan 1, 2005

By L. F. Barrett, D. E. Cameron, J. C. Wilson

Exploration by Anaconda Minerals Co. in the Rico area from 1978 through 1983 resulted in dis¬covery of the Silver Creek molybdenum deposit. The drill-indicated resource is 40 Mt (44 million st) of 0.31% Mo, and projections suggest that the deposit may exceed 182 Mt (200 million st). No source intrusion has been intersected by drilling, but its presence is sugested by intramineral silicic alkali-alaskite porphyry dikes observed at the surface and in drill holes. Age dates and fluid inclusion studies indicate that the deposit was formed 5.2 ± 0.2 m.y. ago and that more than 1200 (3937 ft) of cover has since been removed by erosion. The deposit is hosted by Precambrian quartzite and greenstone, and Paleozoic sediments. Three prominent faults intersect in the vicinity of the molybdenum deposit, and one of these, the Last Chance fault, strongly influenced the shape and location of the deposit. The juxtaposition of host rocks across the Last Chance fault reflects significant offset spanning at least three different periods. Wallrock alteration associated with the deposit includes potassic, phyllic, and propylitic zones in noncalcareous rocks and garnet and anhydrite-diopside zones in the carbonates. All +0.2% Mo mineralization is within the potassic and garnet zones. Premineral faults that intersect the deposit contain the only surface molybdenum, tungsten, and fluorine anomalies. Dispersion halos of the indicator elements were defined by drilling in the discovery phase of exploration, and are particularly well-developed in the hanging wall of the Last Chance fault.

Jan 1, 1987

By William C. Grady

The environmental and economic problem created by pyrite in coal are well documented. The removal of pyritic sulfur prior to, or during, utilization has been the object of considerable research, however, much of this research has proceeded without a proper knowledge of the microscopic occurrences of pyrite in coal. This paper investigates the forms, occurrences, and variations in the distribution of pyrite in major West Virginia coal scan. Twenty-nine samples from twenty-two major west Virginia coal scans were selected for this study (see Table I). The samples were selected so as to be representative of the major coal producing areas of the state. All samples, except five, were collected at active surface mines, as indicated in Table I, and all except one were channel samples. The time interval between sampling and preparation of polished microblocks varied from two months to two years, though most were prepared within three months of collection. Grinding, screen¬ing, and riffling of samples to obtain 250 grams of -20 mesh coal for microscopic analysis strictly followed ASTM procedure D2013-72.

Jan 1, 1976

By Stanislaw Wasilewski, Zdzislaw Krzystanek

The CMC-3 new generation system for continuous methane monitoring enables on-line measurement of methane concentration within the range of 0-100% CH4 with a great autonomy of operation. In principle the system has been worked out in the asspect of hazard detection in mines endangered with rock and gas outbursts. But after last crash in the Halemba colliery, according to the recommendation of the after-accident committee, the system was directed to this colliery for operational tests. The paper describes construction and functions of this system and gives some results of tests conducted at the Halemba colliery. The results point out the necessity of using monitoring equipment of continuous operation in mines of high dynamics of methane emission. INTRODUCTION Commonly used in Polish coal mining the methane monitoring systems of CTT/63/46 Up or CMM-20 and CMC-1 type are based on cyclic measurements with 4-minute repetition of measurements. This period has been stated sufficient from viewpoint of methane emission dynamics under normal exploatation. In these systems, automatic switching-off electrical power is performed by the surface station, i.e in case of detecting exceeded concentration value the station generates control pulse signal which actuates the switchng-off devices CRA and IZZO. Such a way of disconnection causes a considerable time delay, up to several minutes, in electric power break at hazardous areas. In the methane monitoring system with the new CMC-3 station, the different phylosophy of operation has been applied. Measurement of methane concentration is performed in a continnous way. In case of exceeding the alarm value, immediate control of the IZZO unit directly by methane monitor follows and consequently energy break without necessity of communicating with the surface station. Alarm values are set directly in methane monitor. The system ensures central powering of underground equipment from the surface, and in case of power failure the methane monitor equipped with battery operates autonomously for about 12 hours. Such an extention of the methane monitor funtionality has been achieved thanks to the use of internal microprocessor controller. The system with the CMC-3 station has been worked out in the aspect of methane hazard detection in mines exposed to gas outbursts. But after last gas explosion, according the desicion of the After-accident Commitee, the system was installed in the Halemba coliery where it underwent operational tests. Besides

Jan 1, 1993

By Jacques Mongrain, Serge Barbeau, Gary Brierley

The Communaute Urbaine de Montreal is currently involved in construction of the South Interceptor which consists of 53 kilometers (33 miles) of 1,800 mm (6.0 ft) to 5,400 mm (18.0 ft) diameter tunnels for the purpose of collecting, storing, and delivering sanitary and combined sewage to the treatment plant. Work is divided into ten separate contracts; nine of which have already been bid. The purpose of this paper is to describe construction activities that have been performed through the end of 1986 with emphasis on a general layout of facilities, a summary of subsurface conditions, and brief descriptions of actual construction activities for the six contracts where tunneling has been performed. All projects are being excavated with tunnel boring machines.

Jan 1, 1987

By D. Lee Petersen, Charles R. Nelson, Marvin Marshak

INTRODUCTION Construction is underway on a laboratory cavern 713 m below surface at the Soudan Mine, Tower-Soudan State Park, in northeastern Minnesota. The 13.9 in wide by 11.6 m high by 71.8 in long cavern will provide a laboratory space for basic research in physics, in which experiments can be conducted with greatly reduced interference from cosmic radiation. A first generation experiment, called the Soudan 1 detector, is currently operating in a converted drift 591 in below surface at the mine. The initial phase of the Soudan 2 detector will be an 1100-metric ton unit, which will occupy approximately a 19 m length of the cavern. Control and monitoring equipment will be in a prefabricated shop office enclosure erected in the cavern. The location and planned usage for the laboratory cavern present special excavation, lining, and outfitting requirements. Temperature and humidity control, a relatively clean dust-free environment, and a long service life are required. Low cost and risk to the owner were basic requirements due to the nature of the funding. The most common type of site selected to meet these two constraints is either an operational mine or a civil works facility such as a road tunnel. There are often serious problems for such laboratories because of ongoing operations such as blasting, hauling, etc. Most of these problems do not exist for the Soudan 2 laboratory because the mine is used as a historical site with regular tours only in the summer season. The laboratory owner, the University of Minnesota, and the park owner, Minnesota Department of Natural Resources, are both public agencies of the

Jan 1, 1985

By R. Robertson

Dense medium cyclones are the preferred means for cleaning 112 in. x 14 Mesh to 28 Mesh (12.7 mm x 1.0 mm to 0.6 mm) raw coal and are becoming a common choice for cleaning raw coal from a nominal top size of 2-1/2 in. to 3 in. (63.5 mm to 76.2 mm) down to 14 Mesh to 28 Mesh (1.0 mm to 0.6 mm). During the last ten years, dense medium cyclone circuitry design has undergone changes which have combined to improve process efficiency. This paper describes these improvements and compares present day design with the design used prior to the mid 1980's. Improvements in the following areas are described: Raw coal desliming, cyclone configuration, drain and rinse applications, dilute medium circuitry, and instrumentation and control.

Jan 1, 1997

By J. Felipe Costa, Andrew H. White, Marcot T. M. B. Vilhena

Ordinary kriiing (OK) is an interpolation algorithm mostly used in earth sciences applications where it provides satisfactory results. Robust kriging (RK) is an alternative algorithm which at- tempts to minimise the problems caused by the existence of outlier values within a given data set. Robust kriging essentially consists of an editing step prior to running the traditional OK method. This study compares the interpolation results obtained by OK and RK. Two data sets were used. The first data set consists of 140 samples mimicking a drilling survey named cluster.dat. An additional feature of this sample data is that its parent population, the reference data set, is available, thus permitting direct quantitative assessment of the effectiveness of a given estimation technique. The second data set consists of a grid sampled at 1x1 m. The estimates obtained by OK and RK using cluster.dat were compared to the reference data set. RK provided better results in terms of quality of the estimates than OK

Jan 1, 1996

By Andrzej Walentek

This paper presents the results of numerical modeling of the fractured zone around longwall gateroads. The numerical computations have been based on the results of underground measurements of the fractured zone around longwall gateroads, which were performed for various geological and mining conditions and measured with the use of the endoscopic method with a digital camera. Having results of the underground investigations, trials of duplicating them by the Finite Element Method using software PHASE and the Hoek-Brown failure criterion were performed. In order that the fractured zone predicted by the model-based computations closely simulate that measured underground, some selected parameters in the Hoek-Brown failure criterion were modified based on the earlier determined relations used for prediction of the roof-to-floor convergence in longwall gateroads. As a result, the model-based computations produce results very close to those obtained from the underground measurements. Determination of the fractured-rock zone around the mine roads is of great importance to mining practice, especially in planning and designing supports for longwall gateroads. The influence of the front abutment pressure causes the fractured rock zone around the roads to increase and results in an increase of support load. Moreover, proper determination of the fractured rock zone is one of basic elements in the process of planning roof bolting for mine workings.

Jan 1, 2009

By J. Hanna

Four Ca-bentonitic clays from Alabama were evaluated for use in Diammonium Phosphate (DAP) or Urea Ammonium Nitrate (UAN) fertilizer suspensions. The viscosity and gel strength of suspensions prepared with different proportions of a Western bentonite clay and sodium exchanged Alabama clays, were measured as a function of clay content and dispersant concentration. The results obtained suggested that three of the Alabama Ca-bentonites would replace about 40% of the more expensive Western bentonite in UAN and DAP fertilizer suspensions. The performance of the Na-modified clays, prepared according to the TVA soda ash method, was as good or even better than those observed for the Mg-, Na/Mg-or K-modified clays. The TVA clay modification procedure appears to be reliable and cost effective.

Jan 1, 1989

By R. J. Puchala, B. M. Hawrylewicz

High voltage electrical discharge in water causes instantaneous release of accumulated energy into water. The experiment described in this paper regards the utilization of the electric discharge phenomenon in rock splitting. The pressure in the shock waves created by the discharge inside a small volume of water enclosed in solid rock causes stresses which can result in breakage of rock. Holes drilled in tested samples were notched in order to weaken the tensile strength of the rock and achieve a uniformly directed split. The influence of the notches was theoretically analysed and compared with experimental data. Results of the tests have been statistically elaborated in order to correlate the newly-created surface to the energy supplied.

Jan 1, 1986

By J. M. Carter, Rodney H. Sergent, L. E. Kun, J. T. Pressly

Underground mine service water in South Africa is used for dust suppression and cooling the environment as well as the pneumatic rock drills. Although the chilled water is not intended for potable use, it is often used as drinking water by mining personnel. Furthermore, droplets sprayed are liable to be inhaled. The water is recirculated on a continuous basis and is a potential source of infection by intestinal microorganisms or water-borne diseases such as cholera or typhoid. In order to protect the health of the underground workforce it is customary to disinfect the chilled service water, The bacteriological quality of the water is monitored by enumerating total aerobic bacteria (TAB), total coliforms (C C) and Escherichia coli (E Coli). E coli is an indicator of human faeca_l __ - -- contamination, The bacteriological standard specified by the Anglo American Corporation for mine service water is less than 3000 TA B per 100ml, less than 2 CC per ml and the total absence of E Coli. There are several disinfecting agents available for use. Among these are UV irradiation, ozone, chlorine dioxide and compounds that produce hypobromous and hypochlorous acids. Historically, the methods of treatment have been chlorine based and include the use of gaseous chlorine (surface installations only), calcium hypochlorite granules or tablets, chlorinated cyanurate tablets, sodium hypochlorite solutions and hypochlorite produced by electrolysis.

Jan 1, 1991

By William H. Lehr

A 4200 ton-per- hour marine transfer terminal, where river and oceangoing vessels simultaneously exchange cargos of coal and phosphate rock, is now in operation near the mouth of the Mississippi. Its materials handling machinery includes a bucket ladder barge unloader; a rope operated clamshell bucket unloader; a coal loader; and a rail mounted bucket wheel machine. The design and operation of this equipment is described as are the docks and conveying, breasting and barge-haul systems in use at the facility. Design considerations imposed by soil and river conditions, geography, operating needs and investment requirements are discussed. The economic significance of design and shipping innovations introduced by this facility is noted.

Jan 1, 1967

By C. Demir, M. S. Celik, I. Gülgonul

Na-feldspar (albite) and K-feldspar (microcline or orthoclase) are major feldspar minerals with identical crystal structures and physicochemical properties. Flotation appears to be a unique method of separating these minerals. Fundamental studies on amine/feldspar system in the presence of monovalent salts showed that separation of these feldspar minerals by flotation is possible at certain concentration of monovalent salts in HF medium and natural pH. A comparison between natural pH and HF medium indicates that the latter provides a better selectivity at the expense of higher collector requirement. A general mechanism for both systems involving an ion exchange between the uncommon ions and adsorption of the common ions is proposed to be responsible for creating differences in the charge of albite and microcline unto which amine adsorbs.

Jan 1, 2002

By MARK J. VANARELLI

Estimating groundwater inflows in rock deep tunnels is critical to the safety of personnel constructing the tunnel and the cost of construction. This paper presents two case studies for estimating steady-state groundwater inflows into deep rock tunnels. The case studies included the Chattahoochee and Nancy Creek tunnels. In this paper, statistical methods were applied to packer test data obtained from exploratory borings during geotechnical site investigations. A semi-empirical procedure was utilized for estimating groundwater inflows into these deep rock tunnels. The Chattahoochee and Nancy Creek tunnels are deep rock tunnels which exhibit radial flow conditions. For the radial flow condition, a statistical analysis presented in this paper indicates that the semi-empirical procedure works well; however, variations in the procedure and/or an insufficient amount of testing could lead to underestimations of the inflow quantities. Packer test data plotted in histograms were observed in all cases to be log-normally distributed for the radial flow condition. Modeling using Monte Carlo simulations was observed to be an effective tool for removing irregularities in the distribution of the data and incorporating high-end permeability data to derive reasonable groundwater inflow estimates.

Jun 13, 2021

By W. P. Stroud, R. S. Dennen

A ground penetrating synthetic pulse radar system has been used by the US Bureau of Mines to probe into a coal pillar to locate hidden structures or anomalies. Direct matrix inversion was used to obtain a velocity image of the interior of the pillar. The reconstructed image showed the existence and location of a relatively low velocity material within the pillar. Core samples were taken from the pillar in a region surrounding the low velocity material. Analysis of the cores showed the presence of a clay vein coinciding with the low velocity material imaged in the tomogram.

Jan 1, 1992

By Gregory Owen Lewis

The use of gravity concentration as a means of recovering the 'free' gold component from alluvial and milled ore products is widely used and is receiving increasing attention, particularly with the introduction of the centrifugal-type concentrating units. Because of ever-increasing mining and processing costs and a decline in the gold price, it has become important that the recov­ery efficiency from concentrates is improved so as to increase the yield of bankable gold from this primary recovery step. This paper outlines an alternative hydrometallurgical approach aimed at achieving overall gold recoveries in excess of 98%, together with the elimination of any secondary residue streams which, in the case of conventional treatment methods, require re-processing. An adaptation to the Minataur™ Process technology is being applied with the proposed method, incorpo­rating the pre-treatment of the concentrate, oxidative leaching of the pre-treatment residue, followed by precipitation of a high­purity gold. This route is seen to have application in all scales of operation. Selected results from laboratory-scale testwork are presented to highlight the discussion.

Jan 1, 1998

By X. M. Yuan

In the flotation of Zn-Pb ores, sphalerite is floated following copper sulfide activation. In this type of sulfide ore, pyrite is commonly treated as a gangue, and poor selectivity between sphalerite and pyrite/quartz is often reported. But pyrite may also appear in association with gold, and flotation of such auriferous sulfides is of great importance in many countries (e.g. South Africa, Australia). In the cationic flotation of sulfide ores with dodecyl amine, sphalerite can be floated while depressing quartz and pyrite. While in a well-aerated pulp in the presence of lime (especially after oxidation with H2O2) the cationic flotation of pyrite is depressed, oxidation of pyrite in the presence of Na2S makes it floatable with amines even in very alkaline environment.

Jan 1, 2002

By Claus Becker

The new, 2.600 m long pipe under the river Elbe in Hamburg/Germany required for 2 traffic lanes, emergency lane and space for utilities a boring diameter of 14,20 m(46,6 ft). According the geology (glacial deposits consisting of clay, sand and marl, all containing big boulders) a Slurry-Shield with crusher was selected. With a minimum cover of 7 m and a maximum pressure of 5,6 bar extensive ground treatment was necessary to make the drive feasible. The machine contains a lot of new developments. The drive was finished in spring 2000 so all experiences can be reported. A special risk sharing contract avoided completely litigation.

Jan 1, 2001