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Raises are widely constructed underground in hard rock mining for ventilation, material transport or emergency escape. The four major raise excavation methods, Drop Raise, Conventional, Alimak and Raise Bore can be divided into two categories from ground control point of view, one ground support can be installed during excavation, the other not. Excavation method must be chosen carefully to keep the raise wall in stable state during excavation and make sure enough rock stand-up time to install ground support if needed. If rock quality is permitted and there is no strict space limitation, raise bore method which is the only method that ground support can not be installed after the whole excavation is finished should be considered first because it is faster, cheaper, safer and less disturbance to the hosting rock. Support may or may not be needed depends on the purpose of the raise and rock quality. In high quality hosting rocks, if the raise is only for ventilation or material transfer, support may be not needed. If it is for emergency escape or escape and ventilation, which provide or require personnel access, the whole raise must be supported either in high or low quality rock. Based on on site data collection, construction and raise utilization, this paper gave out the rule of thumb how to decide an excavation method. After purpose of the raise, required raise diameter (size) and raise site options being known, geotechnical data collection is the next important step in a raise project.

Jan 1, 2011

By G. Bräuner

The methods of burst control treated in the authors' very informative paper have been applied in the Ruhr Coalfield, Germany, for more than 20 years and have proved to be highly effective. It might be interesting here to mention a few experiences: • The symptoms of critical stresses when drilling with small diameters ("test drilling") are essentially the same as described. However, we consider the situation safe if these symptoms occur beyond a certain distance ahead of the face. • That safety distance equals three times the seam thickness plus the daily advance. It is the total seam thickness that counts, not merely the mined portion. • Critical stresses within the safety distance are dissolved by so-called destressing measures: drilling with heavier equip¬ment, blasting, or water infusion. • To avoid bump initiation, the destressing operations should begin at the sides of the stressed zone rather than in the middle. • As to water injection, there are two different principles. If the situation is critical already, high pressures are applied for hydraulic fracturing. If the stresses still allow to drill deep holes, the fluid pressure is kept low and acts for a longer time. This is to make the coal break successively instead of violently - a long-term precaution. • When the stresses are very high, destressing is the most appropriate means. We mostly drill with 95 mm-diam (3.7 in. - diam). The techniques in detail are somewhat complex and sub¬ject to modifications. But the general idea is to accomplish burst prevention by controlling the potential burst situations.

Jan 1, 1989

By James J. Brady

The basic story at Bear Swamp was how to excavate an underground chamber 79 feet wide by 227 feet long and 150 feet high, along with the related access, tarbrace, leads, power tunnels and shafts, do it under cost and ahead of schedule and still have just about everybody love you. The isometric sketch of the overall project follows. I won't go into any of the details of the physical scope at this point. Instead, we'll bring out the sizes, grades, particular problems of the different areas as we cover them. First of all, let's establish that Bear Swamp was a Target Estimate - Fee with Incentives type of contract. Gates and Fox's contract was with the project's general contractor, J. A. Jones. We were one of three contractors who submitted proposals and estimates to Jones. After much negotiation and many submittals, Gates and Fox was notified we had been selected to do the underground excavation on April 12, 1971. We had our first people back on site in two days, set up a temporary office, made our first steel order for jumbo erection, pacing our jumbo construction to meet the date when J. A. Jones would have the access portal ready for us. The shops, yards, dry house, compressor building were all erected as sites were designated for our use. At last, on Thursday, June 3, we trimmed the face and moved our 9-machine Euclid jumbo up a hastily constructed haul road and started our portal preparation of the access tunnel.

Jan 1, 1974

By Bruce D. Hulman, Robert .. F. Gorman

Introduction Groundwater resource evaluation has historically required extensive field investigative work, usually at great cost. More recently, the advent of the microcomputer has made difficult aquifer and groundwater evaluations comparatively simple and less expensive. A groundwater model is a numeric solution to a set of equations that calculates the water level in an aquifer or other types of water bearing strata. A computer will execute the solution of the set of equations rapidly and thereby permit evaluation of large amounts of hydrogeologic data rapidly. Computer modeling of groundwater resources is very often used to forecast the effects of multiple uses of a single groundwater resource. Modeling of heavily used aquifers has proven to be beneficial for averting problems arising from competitive use of a groundwater resource. This paper describes the work tasks performed in order to evaluate a large alluvial aquifer and thereby predict the hydrologic impact of additional groundwater withdrawal. Purpose and Scope Neyer, Tiseo & Hindo, Ltd. (NTH) was retained to evaluate the groundwater supply potential of the Missouri River alluvium underlying the Fairfax District in Kansas City, Kansas (Figure 1). The proposed groundwater supply is being considered for industrial use as non-contact process water and a heat exchange medium for plant climate control. The anticipated peak groundwater demand is estimated to exceed 30 million gallons per day (MGD) during the summer months, with an average daily demand of nearly 25 MGD. The proposed groundwater supply was to be developed from 15 large-diameter production wells located at positions that would minimize potential interference.

Jan 1, 1987

By A. Papandreou

Industrial wastes nowadays constitute one of the most serious threats for the future of our planet. Researchers around the world have very often proposed many kind of solutions in the management problem of industrial effluents. However in most cases suggested solutions are either too expensive to be applied in industrial scale, or they just transfer the problem (e.g. precipitation creates dangerous sludge) and so they create an even greater problem and threat. In the present study the exploitation of valuable hydraulic and adsorption properties of fly ash is studied. Fly ash can easily and cheaply be shaped into stable pellets. After ageing for a sort period of time, these structures can be used as adsorbents for the removal of heavy metals from industrial effluents. Experiments in aqueous solutions have shown excellent adsorption behavior concerning the removal of cadmium, copper, lead, chromium (III) and zinc. The advantage of this technology, except low cost, is that after saturation the pellets can be easily removed from the liquid phase and stabilized in concrete structures without any problem of desorption or leaching. Moreover in these structures a significant amount of cement in the concrete can be replaced by raw fly ash. (Ashcrete as it is called). The utilization of an industrial byproduct as fly ash in the form of pellets as adsorption means and their stabilization with concrete (or ashcrete) combines the useful properties of a solid waste in the treatment of liquid effluents and constitutes a green low cost technology.

Jan 1, 2006

By Drupad B. Desai, C. C. Ku

INTRODUCTION The Laurens Street section of the Northwest Line of the Baltimore Region Rapid Transit System, located along Pennsylvania Avenue between Pitcher Street and North Avenue is situated in material which cannot be definitely categorized as soil or rock. However, in the area of residual soils in which these tunnels were constructed, considerable attention was required to determine the character of the ground so that the designers and the constructors could properly evaluate the behavior of the ground and plan their respective efforts accordingly. The Laurens Street sections structures consist of twin rock tunnels, station structure, traction power substation, vent shafts at both ends of the station, the midline vent shaft, and the twin mixed-face tunnels. This paper concentrates on the mixed-face tunnels which extend from Station 99+67.03 (O.B.) to Station 102+49.00 (O.B.) at the southern end of the section. Since the completion of the design of this project, the Laurens Street section has been renamed the Upton Station. (See Figures 1 and 2). SUBSURFACE INVESTIGATIONS At early stages, three preliminary studies were performed by the General Soils Consultant (Ref. 1, 2, & 3). The purpose of the first study was to ascertain the generalized geological and subsurface conditions which might be encountered in the region. No borings were performed for this study. A limited number of test borings were performed for the second study, which included subsurface data for the Northwest and South Lines of the Transit System. Three borings were

Jan 1, 1981

By David M. Mchaina, Allan E. Hall, W. C. H. Kruining, Alan Coode, Stephen Hardcastle

This paper details an investigation into the feasibility of recirculating mine exhaust air in Saskatchewan potash mines. This project was initiated following a previous study at Ruttan Mine, Manitoba, which indicated that recirculation of exhaust air to reduce winter heating costs was feasible. The potash industry was selected for study because the mines use a minimum of blasting in their production methods and the exhaust temperature is significantly higher than that of most metal mines. These factors simplify the monitoring system required and have the potential for greater waste heat recovery. A series of measurements of underground mine pollutants was made at the main exhaust and intake shafts in order to determine the feasibility of introducing controlled recirculation of exhaust air. An experimental recirculation circuit was created by opening two existing doors situated between the return and intake shafts. During this recirculation trial, the air quality parameters at the intake, mixed intake and exhaust measuring stations were monitored. The results obtained from a questionnaire circulated to the regulatory agency and the major potash producers together with results obtained from underground field studies at Central Canada Potash (CCP) Division of Noranda Minerals indicated that controlled recirculation of mine exhaust air has potential application in these mines either to reduce heating costs and/ or to increase the face air quantities. A recirculation system is to be designed in conjunction with CCP and the Saskatchewan Ministry of Labour, Mine Safety Unit to attempt to implement a working recirculation system for CCP.

Jan 1, 1989

By R. L. Grayson, N. P. Reddy, D. A. Kinzler, S. Yuan, W. R. Myers, R. A. Wells

An examination was conducted on the impact of roof conditions and the mining cycle in determining a representative respirable mass concentration at the mid-shearer location on a longwall panel. Multiple personal gravimetric dust samplers, operated at a flow rate of 2.0 lpm, were used at different locations along the face to isolate the concentrations and variances associated with good and bad roof conditions under both the cutting and cleaning mode of operation. The number of samples needed to estimate the population variance at a given confidence level was analyzed. In addition, the statistical analysis showed that the coefficient of variation of dust concentrations at different locations and under different conditions ranged from 0.185 to 0.475, with an average value of 0.283. The estimates of the average dust concentration for a shift and the variance of the dust concentrations were calculated. A total of 48 data points were available for an [a x b] factorial ANOVA (analysis of variance). The estimates of the variance components were determined. The results from F-tests indicated that both the roof conditions and mining operations had a significant effect on the respirable dust concentration. There was no significant interaction effect between mining operations and roof conditions. In conclusion, this study shows that not only should sampling and analytical errors be considered in determining the required number of samples for a good estimate of the long-range exposures of miners, but also fluctuations of concentrations due to mining operations and geological conditions should be taken into account.

Jan 1, 1991

By P. Jacquin

Many a deposit estimation has been carried out since geostatistical methods were first implemented. To date however few mining programs have totally been completed and even fewer comparisons can be drawn between estimated reserves and extracted ore tonnages. Aluminium Pechiney work a number of bauxite mines in Southern France. As from 1969 they modified their deposit estimation methods, giving up traditional approaches and opting for geostatistics. At that time, the authors of this paper were entrusted with the first geostatistical estimations and in particular, those concerning the deposits mentioned herein. Over the past decade a number of deposits have been worked out and we thought it interesting to report about comparative results. French bauxite deposits are of the karstic, as opposed to the lateritic, type. The bauxite, formed at some distance of the present-day deposit, was brought to and trapped in limestone karst pits. Subsequent physical and chemical alterations may have taken place : silica and carbonate drifts, recent karst slips. The morphology of these deposits is often rather complicated. The deposits are small from a few hundred thousand to a few million tons at the most. The overburden thickness usually precludes open mining. Mining investments and financial risks are often high, making it necessary to obtain optimal information on the deposit considered for mining. For the three cases brought up in this paper, deposit sizes, exploration methods and conclusions differ. They are brought up mainly to show the advantages inherent to a quality geostatistical study and the lessons drawn by Aluminium Pechiney.

Jan 1, 1982

By R. D. Lama

Coal mining is one of the major sources of methane release to the atmosphere by human industrial activities and is believed to contribute to -30% of the total methane emissions from industrial activities. In 1993, world saleable black coal production, attained almost 3.5 billion tonnes from which around 65% was produced underground. Coal in underground mines can contain high quantities of methane and some deep coal seams have methane content as high as 50 cubic meters per tonne of coal. Gas is re- leased during coal mining from the mined seam and in a higher degree from the neighboring unmined seams and gas bearing strata which are fractured as mining advances. This paper de- scribes a study which was undertaken to estimate the extent of methane emissions from coal mining in the world. Measured emission related data were collected from most underground coal producing countries in the world. The data included methane flows in the ventilation system, methane flows in gas drainage system, in-situ gas content, methane utilization and coal production. More comprehensive data were collected from a range of gassy and non-gassy Australian mines. Residual gas content of samples from run of mine were also measured. Using the Australian data, mathematical expressions were established to evaluate methane emissions as a function of coal production and in-situ gas content for other mines. These emission models were then used to evaluate the emissions for the countries or coal basins without measured emission data. Trends in methane emissions from underground mining for the year 2000 and beyond were also estimated.

Jan 1, 1997

By Peter J. Tarkoy, Terence G. McCusker

INTRODUCTION The discovery of oil and gas reserves in the North American Arctic has led to substantial thought being given to their development. Systems adequate for exploration are not always, or even often, suitable for permanent installations. Combinations of offshore pipeline, drilling ships, platforms, sub-sea systems, sand islands and -ice island bases have been proposed. However, conditions in the Arctic are such that these methods may be difficult or impossible to implement. Problems exist with (1) the freezing of the Arctic Ocean surface for 9 - 10 months per year, (2) the movement of sea ice, (3) scouring of bottom sediments by ice islands and icebergs to great depths below the ocean bottom and (4) deep water channels. Any method which can avoid the problems associated with surface construction in these very adverse conditions merits detailed examination. One of the proposed solutions is to tunnel from a convenient or available access point to a point within the field, construct a chamber large enough to accommodate the drilling equipment and drill the development wells in a protected environment. Service and delivery lines would use the access tunnel and further tunnels and chambers would be constructed in a radiating pattern to develop the whole field. In order to determine the feasibility of underground construction in the North American Arctic, it is first necessary to understand the geologic and environmental factors which would affect such construction, to be knowledgeable concerning the problems and then to consider the techniques appropriate to the conditions which will be encountered, bearing in mind the need to minimize both con-

Jan 1, 1976

By C. P. Siess, S. L. Paul, E. H. Gaylord

Several types of tunnel supports are being investigated experimentally and analytically at the University of Illinois at Urbana-Champaign under the sponsorship of the Federal Railroad Administration, Department of Transportation. The results of work on two types will be discussed here. These are steel sets and continuous, monolithic steel-fiber-reinforced concrete liners. The latter is a model of a short length of liner that might result from a continuous slip-forming operation in a tunnel excavated with a boring machine. Tests have been performed on both types of support and analyses are being developed which will greatly broaden the scope of the test program. The objective of these studies is to improve the understanding of basic behavior of these supports, and to develop techniques for their analysis. The analyses will then be used to perform parameter studies that will lead to more rational procedures for structural design. The tests provide a check on the accuracy of the analysis and demonstrate the overall behavior and modes of failure. Another part of the project is concerned with the interaction of support and medium, and thus prediction of loads for the supports. These studies are presented in greater detail in a recent report (1). A brief outline of results obtained to date are presented in this paper. STUDIES OF STEEL SETS Description of Set Tests The sets tested were of the horseshoe type with a 5-ft radius arch section and 7-ft straight legs. They had bolted joints at the crown

Jan 1, 1974

By Jesse L. . Jr. You

Tunnels in the granitic Climax stock at the Nevada Test Site were inspected for keyblock occurrence. Thirteen relatively large pyramidal keyblocks were located in about 230 m (750 it) of tunnel. Orientations, dimensions, joint roughness coefficients, and joint compressive strengths were measured for the faces of nine keyblocks. The measurements were used to back-analyze keyblock stability to check the validity of a numerical model for keyblock behavior. A newly developed three-dimensional numerical model correctly predicted whether or not each keyblock failed in six of eight cases. The two exceptions involved stress conditions and keyblock locations that clearly violated the assumptions that underlie the stability model. The observations also allowed the effect of tunnel orientation on keyblock occurrence to be evaluated. Of the thirteen observed keyblocks, nine large blocks were found in less than 30 m (100 ft) of the Piledriver drift (which runs N56E) while only four blocks of comparable size were observed in 200 m (656 ft) of the Spent Fuel Test--Climax drifts (N61W). The orientations of the keyblock faces were checked against known discontinuity set orientations; some of the faces correlated well with mean set orientations, whi.le other faces were fringe members of sets. Stereographic techniques were used to examine the frequency of keyblock occurrence and to determine the maximum keyblock size that could be encountered with a given combination of discontinuities. Keyblock occurrence was found to be affected by tunnel orientation in a predictable way; this can be used to guide or improve tunnel design practices.

Jan 1, 1986

By L. Xu, N. I. Jayaraman, R. Bhaskar

The objective of this study is to develop a better understanding of the collection characteristics of dust measurement instruments used in mine dust control research with respect to properties of quartz and coal dust. Coal and quartz dust of narrow sues, with aerodynamic median diameters being approximately 2 µm, 4 µm and 10 µm, with quartz contents of l0%, 20%, 30%, 40% and 50%, were released in an aerosol characterization chamber using a fluidized bed aerosol generator. Dust was collected in MSA personal gravimetric samplers with l0-mm nylon cyclones, total dust samplers and Sierra 298 inertial cascade impactors. The samples were analyzed for mass and quartz content. A total of 21 experiments were performed for this study. The mass and quartz collection efficiencies of the total and respirable dust samplers and the impactor were determined. The data show that the amount of dust collected by the respirable dust sampler (respirable + oversize dust trapped in the cyclone pre-classifier) was, in general, less than the amount collected by the total dust sampler. The amount of dust collected by the impactor was higher than that collected by the total dust sampler. Quartz analyses of the airborne dust samples showed that the total dust and respirable dust samplers (including oversize dust) collect less quartz dust than at inertial impactor. The larger the median particle sire of the quartz and coal mixture, the lower the quart content of the dust collected in the samplers. For all three sires, the impactor was a better collector of quartz than the other instruments.

Jan 1, 1994

The transfer of Langmuir-Blodgett (LB) monolayers of collector molecules to the surface of mineral crystals is an excellent method for the study of collector adsorption phenomena and is of particular significance in the understanding and development of improved flotation separations. The fatty acid/fluorite and amine/sylvite potation systems were investigated by the Fourier transform infrared/internal reflection spectroscopy (FT-IR/IRS) examination of transferred LB monolayers of collector molecules at the surfaces of the mineral crystals. The [ir]-A isotherm study of fatty acid and amine, typical anionic and cationic collectors, showed the different packing trends dependent upon the pH and/or type of subphase. This result clearly reflects the effect of pH on compound formation and dissociation of the collector molecules. Identification of the collector adsorption state and confirmation of the validity of the FT-IR/IRS adsorption density equation were included in this research effort. This allowed for a detailed discussion of collector adsorption phenomena. As a result of these experiments, it is possible to relate the hydrophobic character of a surface to the nature of the adsorbed collector structure and thus describe flotation behavior in greater detail. For example, it appears that in the case of oleate/ fluorite the equivalent of an LB monolayer can form spontaneously during adsorption from solution, and this structure is known as a self-assembled monolayer (SAM). Such a state is significantly more hydrophobic than the oleate structure which forms on the calcite surface at an equivalent adsorption density.

Jan 1, 1996

By K. S. E. Forssberg, M. I. Hallin

In many cases, the reuse of process water in flotation plants is desirable both for plant operating reasons and for environmental protection. The main advantages are better housekeeping of fresh water and process chemicals together with the reduction of polluting species to the environment. There are however a number of problems involved in the use of recycled process water. The main problem is that recycling sometimes has a deterious effect on the process and can occur months after the start of water recycling. The Division of Mineral Processing of Luleå University of Technology has been conducting experiments on recycling of process water at various sulphide plants in Sweden for over ten years. The experiments have been carried out in pilot- and full industial scale, in collaboration with the mining companies operating the plants. Until 1988 investigations were carried out in four different sulphide plants. The objectives of the experiments were: first to document differences in the composition of the process water during recycling; secondly to investigate any changes in the pulp chemistry of the flotation circuits wich may be due to the influence of recycled water; and lastly to establish critical levels, if any. of the parameters measured. While conducting experiments of this kind several things have to be kept in mind. Normally, recycling is done by using tailings pond water as process water. This means that time effects are important, because of the time lag between water input in the tailings pond and the reclaim of that water back to the plant. As will be shown, the

Jan 1, 1989

By Joseph R. Hatch

Previous studies of the Thompson and Temperly ore bodies show alteration aureoles in the Middle Ordovician host-rock limestones, dolomites and shales extending laterally as much as 60m from the ore. Thickness, texture, carbonate and clay mineralogy, major-, minor-, and trace-element contents; and carbonate carbon and carbonate oxygen Isotope compositions of the host rocks all have been significantly altered by hydrothermal processes. Organic geochemical analyses of samples from the basal 8-cm-thick carbonaceous shale bed and immediately overlying limestone bed of the Quimbys Mill Member of the Platteville Formation, collected from within the ore, the alteration aureole, and the unaltered country rock show: 1) solution of carbonates and residual concentration of organic matter, 2) decreases in the volatile (Si) and pyrolytic (S2) hydrocarbon yields In samples of the basal shale from within the ore, 3) decreases in the relative amounts of the lower molecular weight (<nC25) saturated hydrocarbons in samples from the ore, and 4) no changes in either the organic carbon isotope composition or the Rock-Eval or biomarker thermal maturation Indicators. In light of the 125-170°C depositional temperatures documented for the early marmatitic sphalerltes in these deposits by fluid Inclusion studies, the lack of thermal alteration of the organic matter suggests a relatively short mineralization episode, a conclusion supported by the relatively simple sphalerite band stratigraphy. The decreases in the volatile and pyrolytic hydrocarbon yields for shale samples from the ore supports a model for mineral deposition which obtains sulfide through reaction of brine sulfate and indigenous organic matter.

Jan 1, 2013

By Allan M. Johnson

Since 1974 researchers at Michigan Technological University have been studying mine subsidence in the Iron River District of Northern Michigan. The district, which was active from 1881-1978, has had numerous cases of subsidence. Much of the subsidence resulted from rock mass failure but some appeared to have developed primarily in the thick glacial overburden which is a typical feature of this area. This latter observation led to the recognition that some of the surface subsidence was due to piping; i .e., loss of overburden material to the mine voids by groundwater flow (Johnson and Frantti, 1978). The Sherwood Mine was the last mine to operate in the district. With its closedown scheduled for late summer of 1978, a unique opportunity to monitor the mine as it flooded was presented. It was reasoned that with the cessation of pumping, groundwater would rise in the overburden and the mine would flood. The physical characteristics of the mine were favorable for piping to occur as the mine flooded. With the permission of Inland Steel Mining Company and the support of the U. S. Bureau of Mines, a project to monitor the Sherwood Mine for piping subsidence began in June of 1978. This paper present aspects of this study pertinent to the piping-induced subsidence events which occurred at the Sherwood Mine in 1980 and 1981, including acoustic emission monitoring of the subsidence activity, hydrologic monitoring of the groundwater regime and the flooding mine, laboratory modeling of the piping mechanism, and analytic procedures which are under development.

Jan 1, 1982

By W. White

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the author elect, he may distribute copies at the time of the Symposium.

Jan 1, 1986

By Ananda M. Wijesinghe

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the author elect, he may distribute copies at the time of the Symposium.

Jan 1, 1986