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The Anaconda Copper Company reportedly reached an exclusive agreement with Cook Inlet Region, Inc., to explore 24 million acres in south-central Alaska and to share equally with Cook the proceeds of any mineral discovery. According to an Anaconda geologist, "the company is anticipating, based on geologic testing, that it will find significant deposits of copper, lead, and zinc. There is also evidence of the presence of precious metals such as silver and gold, and also strong evidence of strategic minerals such as chrome, platinum, tin, and nickel." Cook Inlet Region, Inc., is owned by 6,500 Alaskan natives. Chile, which has a growing, free-market economy under President Pinochet, reportedly will no longer require companies to obtain prior governmental approval for the exploration and development of new mines.

Jan 1, 1981

By George D. Brunton

The past and present argillaceous rock studies for the U.S. National Waste Terminal Storage Program consist of: (1) evaluation of the geological characteristics of several wide- spread argillaceous formations in the United States; (2) laboratory studies of the physical and chemical properties of selected argillaceous rock samples; and (3) two full-scale in situ surface heater experiments that simulate the emplacement of heat-generating radioactive waste in argillaceous rock.

Jan 1, 1981

By Robert W. Yokom

As the search for new sources of energy and minerals leads to more remote areas of the country - and the world - the need to plan for adequate housing and community facilities for the construction and operations workforces and their families takes on an importance equal to the mining and processing facilities themselves. A corollary to the need for planning is the increasingly crucial need for development companies to devise effective strategies for dealing with the local communities impacted by these projects. Experience has amply demonstrated the high price to be paid for failure to learn this lesson, a price measured in lost productivity, confrontation with local communities, labor turnover, mental health and other social and eocnomic problems. In Sweetwater, Wyoming, a new industrial activity caused the population to double from 18,000 to 36,000 between 1970 and 1974. During that period industrial productivity fell 25 to 40 percent, cost overruns on the principal new industrial facility exceeded 33 percent, annual employee turnover rates climbed above 100 percent, the local mental health clinic workload increased nine times and complaints to the local law enforcement agency increased 60 percent.

Jan 1, 1981

By I. A. Goddard

INTRODUCTION This paper deals with the development of the sublevel open stoping (SLOS) method in lead orebodies at the Isa Mine of Mount Isa Mines Limited, during the last ten years. Open stoping in different forms has been used at the Isa Mine for many years. Prior to the period under review, stopes were small, pillars were not always recovered, and scrapers extracted the ore. By the end of the sixties, the use of load-haul-dump units was becoming more widespread. Wagner ST5's were the mucking units for the lead cut and fill stopes. Some of the open stopes in 5 orebody above 13 level had 100 kW slushers, but the more southerly stopes were the sites for the introduction of diesel front-end loaders for extraction. In the early seventies, new methods were used in the block of six stopes in 2 and 5 orebodies between 8 level and 13 level and a trial stoping project was undertaken in 7 orebody between 11 level and 13 level to determine possible stope dimensions for the extraction of the Racecourse orebodies below 13 level. By the mid-19701s, stoping was well underway in 5, 7 and 8 orebodies between 13 level and 15 level, using the 'triplet' system, incorporating cemented hydraulic fill to allow greater pillar recovery. As the eighties were entered, development of the Racecourse orebodies below 15 level commenced, as did preparations for 1 orebody in the upper levels of the north end of the mine. In both cases, the pillar recovery method has been changed to reduce the amount of cemented fill required for pillar recovery. GEOLOGY Most of the lead orebodies at Isa Mine lie chiefly to the north of the central shaft complex. They are bedded sulphide deposits in a host rock called Urquhart Shale, which dips at roughly 650 to the west. The main minerals are galena and sphalerite, with the silver mineral, freibergite, being contained in the galena. To the hangingwall of the sequence are the Black Star orebodies (1, 2 and 5) which are relatively wide, pyritic and with low to above average grade lead. The Racecourse orebodies (6 to 16) lie to the footwall, and have a large variation in width, low to high grade lead, and gradation in the lead to zinc ratio from north to south. Stope outlines are often determined by economic or engineering considerations rather than geological. The published extraction reserves are 56 million tonnes of primary ore, containing 150 grams of silver per tonne, 6.4% lead and 6.5% zinc. Traditionally, it has been regarded as lead ore, although the dominant revenue earner varies from time to time. In the Black Star orebodies, the ore and hangingwalls are more competent and open stoping has long been used. The major Racecourse orebodies which have been open stoped are 7 and 8 orebodies. This has been where the orebodies are wider (to the south) and where hangingwall conditions allow. This latter aspect has been greatly influenced by the presence of 'silica dolomite1. This tough, relatively homogeneous, non-bedded rock is, in fact, the host rock for the copper mineralisation at Mount Isa, and provides a competent hangingwall for some of the lead stopes. While the shale's bedding and jointing has a major influence on the ground conditions, there is a major fault system which causes local problems. The principal virgin stress direction is perpendicular to the bedding, but the local stress situation is complicated because of shielding by filled stopes in the hangingwall copper orebodies and because of the interaction between orebodies being extracted to the footwall. Most development on strike is mined with a 'shanty-back’, with the back being as close to normal to the bedding as possible. This is near parallel to most jointing and the principal stress direction. Figure 1 is a plan view of 14 level north, which provides a representative horizontal section through the orebodies. A typical cross section is shown in Figure 2. The narrow, parallel footwall orebodies can be seen to differ from the wider hangingwall orebodies.

Jan 1, 1981

By Wils L. Cooley

This report analyzes electrical accident data in the metal/non-metal mining industry. Accidents are categorized to determine their root causes. Special attention is given to accidents associated with inadequate or defective grounding of mine power systems. Recommendations are made concerning proper grounding practice, especially for dredges and for quarries in hard rock or sand. The costs of instituting the recommended practices are estimated for model mine power systems which are based on field data obtained from 37 mines and several electrical contractors. The expected benefits of various suggested safety practices are also estimated.

Jan 1, 1981

By R. N. Hambright

Gaseous and particulate exhaust emissions are characterized for a 1200 Bhp two-stroke cycle diesel, a 1000 Bhp four-stroke cycle pre-combustion chamber diesel, and a 900 Blip four-stroke cycle, direct injection diesel using steady-state modal testing and a versatile exhaust dilution-collection system. In addition, a 1.50 Bhp four-stroke cycle, pre-combustion chamber, turbocharged diesel was characterized for use in experimental water injection evaluations. Water injection downstream of the turbocharger compressor and upstream of the turbocharger exhaust turbine are evaluated for their particulate removal effectiveness on the small turbocharged diesel engine. The water droplets are inertially separated using cyclone separators designed for minimum pressure drop and outsize, lip to 50 percent of the total particulate mass generated was removed using a combination of both inlet and exhaust water injection techniques.

Jan 1, 1981

By G. L. Schroeder, C. H. Summers, D. B. Lindsay

INTRODUCTION The requirement that is placed on owners and operators of underground mines to protect workers against the health hazard of inhaling radioactive materials which are short-lived decay products of 222Rn can be satisfied by applying a considerable variety of what we may call "engineering" solutions as well as a number of "administrative" remedies to the problem. The most obvious of the "engineering" approaches has always been that of forced ventilation, in which relatively clean (i.e., radon-free) air from aboveground is drawn or pushed through the mine workings by a system of fans and ducts. This relatively clean air, in sweeping through the drifts, stopes and haulageways, dilutes the radon and radon-daughter concentrations in the air of the mine, and performs the added beneficial function of removing the daughter-mixture quickly enought to limit grow-in of the longer-lived nuclides in the group that make up the "toxic trio" on which the Working Level (IM) unit is based. Effective as the dilution-ventilation method is for control of WL in most underground mining situations, however, the increasing strictness of control measures that have been imposed on the mining industry over the last two decades have demanded measures of even greater effectiveness. In times of poor markets for yellow-cake and other products of the mines, mine operators are pressed to reduce operating costs, and the installation of additional primary ventilation capacity can be a severe burden on a mine that is already laboring under an unfavorable earning power. When traditional dilution-ventilation systems alone cannot meet the requirement for WI, control, radiation safety engineers and ventilation engineers begin to look at alternatives and auxiliary methods. Since the radon which produces the toxic daughter products originates in the rock of the mine walls, and since, in most United States mines, that rock is a porous sandstone through which air can move under the effect of atmospheric pressure gradients, and through which radon can diffuse relatively freely, one way to help control the growth of WL would be to hinder the escape of radon from that reservior of porous rock. An appealing; method for hindering that natural flux of radon-polluted air from the walls of the mine has long been apparent; namely, to apply a low-permeability coating over the surface of the rock, thus sealing the radon in place and, in theory at least, preventing its escape into the mine air. Our 1970 report to the U.S. Federal Radiation Council on the subject of cost impacts of proposed changes in the occupational standards for exposure of underground uranium miners to airborne radon daughters noted the possibility of using polymeric wall sealants as a means of controlling radon-pollution of mine air. Since that time a number of reports have appeared in the technical literature advocating this technique for restraining the escape of radon from building materials, mill tailings, and other materials containing 226Ra, in addition to the surfaces of underground mine workings. During this period, some controversy has occurred over the question of the probable effectiveness of wall sealants in limiting the escape of radon from the rock. Our 1970 report speculated that flaws (cracks and "pinholes") in the coating might be all but unavoidable in practice, and that even a conservative estimate of the frequency of such flaws would lead to a prediction of ineffectiveness. Hammon et al, in a laboratory evaluation of radon sealants conducted by Lawrence Livermore Laboratory of the University of California in 1975 on behalf of U.S. Bureau of Mines, concluded that a wide variety of polymeric coatings would provide "nearly 100% effectiveness" in restrain¬ing escape of radon from mine wall surfaces if applied in "thicknesses between 5 and 10 mil" (125-250 [y]pm). John Franklin and co-workers at the U.S. Bureau of Mines laboratories in Spokane, Washington, have carried the experiments with polymeric sealants through additional laboratory tests and into actual mine environments, reporting that selected sealants could provide attenuation of radon flux by a factor of four (75-80% reduction). Robert Bates and John Edwards of USBM developed a computer-assisted mathematical/physical model that predicts a relatively small effect of flaws in a low-permeability coating on the radon flux from a sandstone-type matrix. FIELD TEST Since all actual experimental work with wall sealants showed some beneficial effect on radon attenuation (even if not as exciting as the "nearly 100%" predicted by Hammon), USBM was encouraged to extend its evaluation to an actual operating uranium mine, and awarded a contract for that work to Arthur D. Little, Inc. in September 1979. We were fortunate in obtaining the voluntary cooperation of Atlas Minerals Division of Atlas Corp., who operate a mill and several underground mines in and around Moab, Utah. Atlas made available for our use a small T-shaped drift in their Pandora Mine in LaSal, Utah, and provided space for instrumentation and recordkeeping by our field crew in a surface building near the mine entry. Atlas also provided electricity and water to the test site, together with assistance in establishing necessary ventilation, removing rubble from the site, conducting periodic WL surveys and furnishing auxiliary man-power for the heavy hard work of coating the walls with gunite prior to application of the polymeric sealant. The generous coopera-

Jan 1, 1981

By David R. Jessey

Water pollution problems associated with surface metal/nonmetal mines throughout the United States were assessed. Three major problems were identified: acid mine drainage (AMD), toxic concentrations of heavy metals and excessive sedimentation. Several factors affect the type and amount of pollutants generated at a mine site. Among these are hydrologic regime, geology, mineralogy, topography, climate, size of the mineralized area and mining method. Nine surface mines situated in distinctly different settings were visited and their pollution problems studied. These mines were located in Morenci, Arizona; Hayden, Arizona; Sauharita, Arizona; Cobalt, Idaho; Spruce Pine, North Carolina; Iron Mountain, California; Butte, Montana; Fernwood, Idaho; and DeLamar, Idaho-Oregon. A detailed evaluation of the pollution problems at the Morenci mine indicated that a diversion system and treatment pint would be the most effective means of abatement for the existing water quality problems. Based on the study of the Morenci mine and three other porphyry copper mines with differing problems a water management plan was conceived for a new source copper mine. A companion Appendix Volume containing detailed reports on the mine site visits is on file at the US Bureau of Mines Spokane Research Center.

Jan 1, 1981

These proceedings consist of papers presented at three Bureau of Mines Technology Transfer Seminars on ergonomics in the mining industry. These seminars were held in December 1981, and covered topics relating to ergonomics and mining in the areas of the man-machine interface, and design of the work environment. This area of research is directed toward reducing accidents traditionally associated with human error.

Jan 1, 1981

By Daniel I. Carey

Current and potential dragline reclamation usage was evaluated for the U.S. coalfields based on data gathered and analyzed during field surveys, literature reviews and contacts with manufacturers. It was concluded that current wining plans have been adapted to federal and state strip mine and reclamation laws in ways which limit the potential for drag line reclamation systems at active mine sites. At abandoned conventional contour mine sites in steep-sloping areas such as central Appalachia, however, it was found that dragline reclamation systems have great potential application and may be the only practical solution to many reclamation problems. Alternative dragline systems were examined for restoring abandoned sites, and it was concluded that a tower excavator system offered superior characteristics and should be evaluated and developed under field conditions. A testing program was developed to provide a framework for the monitoring and analysis of cost, production and environmental data during a field demonstration of a tower excavator system.

Jan 1, 1981

By D. V. Gaffney

This report presents the results of a three-phase investigation of the feasibility of using cemented coal waste in active underground coal mines to prevent mine subsidence. Coal caste was broadly defines to include waste from both coal preparation plants and coal-fired power plants. Underground systems with potential for cemented backfill are determined through identification of current mining methods and available technologies for cemented backfilling and consideration of materials and systems constraints upon mining and backfilling integration technical concerns including operation, health and safety, materials utilization, environmental impact, applicability and techni¬cal status are assessed for six (6) systems which were identified as potentially feasible. Two (2) of these systems are conceptualized in a hypothetical case history and developed to further assess their operational and economic feasibility. Comparisons of costs among both systems and with costs of surface disposal are presented. Also presented are the conclusions reached concerning the present feasibility of using cemented backfill in active coal mines and potential avenues for further research. Appendices contain further consideration for design of cemented mixtures to be used in backfilling, the results of laboratory testing of mixtures rich varying concentrations c: waste products and cementing agents, and an annealed bibliography

Jan 1, 1981

By Donlad B. Lindsay

This report describes a field-test program to determine the effectiveness of a polymeric wall sealant to reduce the excape of naturally occurring radio-active gas radon from the walls of an underground uranium mine into the ventilation air. A 75-foot-long, dead-end drift with a surface area of about 6,000 ft2 was used as the test site in which the average natural radon flux from the normally dry rock was 16 fCi/cm2-s. The effect on radon emanation of wetting the walls with water to a depth of 3 inches was tested, after which the rock was completely covered with a coating of dry-mix concrete to provide a base for the sealant, an acrylic latex. Sealant was applied in two coats to about 0.25 mm thick. An overall reduction of average radon flux of about 75 pct was achieved. Radon production and other environmental values were measured continuously and automatically by a Bureau of Mines data acquisition system. A commercial microcomputer was programed to convert raw data to engineering units and to perform other useful operations while recording all data on magnetic diskettes. Direct measurements of radon flux from the rock surface were made by a charcoal adsorption technique.

Jan 1, 1981

By Grant Buma

Groundwater restoration is an uranium leaching. Information on the technology, costs, and the current permitting regulations is of vital operators and to firms considering in important aspect of in situ effectiveness of the current state and federal government importance to in situ leach situ leaching. This study, funded by the U. S. Bureau of Mines, describes: (1) all recent restoration attempts at commercial in situ leach operations, (2) restoration costs reported by the industry, (3) empirical equations that predict the amount of groundwater flushing required to meet the current restoration criteria, and (4) in situ uranium permit requirements for the states of Texas, Wyoming, New Mexico, Utah, Montana, Colorado and South Dakota, and Federal requirements.

Jan 1, 1981

By D. E. Van Dillen

Seven configurations for panel entries of a longwall coal mine are compared and ranked according to structural stability. These entry configurations are analyzed using three-dimensional finite element modeling The models include large dimensions to minimize boundary effects, elastoplastic constitutive relations, and simulated excavation and construction of support systems. The stability criteria are formulated in a quantitative manner to facilitate the ranking of the entry configurations. These criteria are based on the expected volume of caved rock in the entry openings. The stability ranking is applied to the entry excavation phase, the headgate phase, and the tailate phase of the entry life cycle. Parametric variations are applied using two-dimensional finite element models to determine the sensitivity to changes in mining and design parameters.

Jan 1, 1981

By David R. Jessey

This volume contains the detailed mine site reports written by the WAPORA, Inc. and KETRON, Inc. staffs. It is a companion Appendix Volume to Control of Water Pollution from Surface Mining Operations. Copies of this report are maintained on Open File at the U.S. Bureau of Mines Research Center, Spokane, Washington.

Jan 1, 1981

By J. A. Kost

A dust-control manual was prepared for use by mine operations personnel. The manual documents state-of-the-art control techniques, dust sampling, and use of personal protective devices. Content addresses advantages/disadvantages of control techniques, design and operating specifications, and implementation and maintenance guidelines. An indexed list of selected references is also included. In addition to the completed manual, this report documents work performed in the course of its preparation.

Jan 1, 1981

By Dermot M. Ross-Brown

The objectives of this generic study were to use numerical modeling techniques to determine under what conditions seismic waves generated by an earthquake might cause instability to an underground opening, or cause fracturing and joint movement that would lead to an increase in the permeability of the rock mass. In general, the study showed that moderate earthquakes (up to 0.41 g) did not cause instability of the tunnel or major fracturing of the rock mass. An artificial rock-burst tremor with high accelerations, however, was found to be amplified around the tunnel, and fracturing occurred as a result of the seismic loading in salt and granite. In shale, even moderate seismic loading resulted in tunnel collapse.

Jan 1, 1981

By John W. Mentz

Phase I study efforts addressed: 1) acid mine drainage formation theory; 2) effects of inundation in reducing acid mine drainage formation; 3) summary information on the types of acid abatement technology currently available and the problems inherent in each; 4) analysis of two potential means of partially inundating abandoned segments of active underground mines to reduce acid formation. This subsequent Phase II Draft Final Report addresses all of the above, but concentrates on and defines Item 4. Seal construction techniques were taken through five logical steps as follows: A) Location Analysis; B) Coal Barrier Pillar Analysis: C) Ground Water Analysis; D) Design Considerations: E) Economic Analysis. The design details of both low wall dams and section seals were discussed in a series of segments: a) Case Histories; b) Feasibility Analysis; and c) Design (including representative calculations). Study efforts showed that both concepts are feasible only in certain mines where the geologic-hydrologic physical makeup is suitable to contain a mine pool. Low wall dams in particular were found to have extremely limited applicability as a means of pollution reduction. Section seals, while clearly dependent upon site specific conditions, have a some what broader range of utility and are more effective in pollution reduction. The proven dramatic reduction in acid mine drainage attributable to inundation makes this a concept that must be considered.

Jan 1, 1981

By Roger F. J. Adam

This report summarizes the principles of safely working steep coal seam using longwall mining methods. It presents the state-of-the-art and identifies the problems which result from seam inclination. Details are given on foreign longwall faces achieving good records of safety and productivity when mining on 30 degree and 50 degree inclined seams. Recommendations for further research are suggested.

Jan 1, 1981

By Michael L. Clar

The U.S. Bureau of Mines contracted a study to determine the feasibility of water diversion and overburden dewatering for underground coal mines in the Appalachian Region. All relevant published literature pertaining to the occurrence and control of surface and groundwater in underground coal mines was reviewed and organized into a bibliography. The impacts of mine water with respect to health and safety, production, environment, and costs were assessed. Sources of water inflow into underground mines were described. A summary description and evaluation of techniques that can be used to reduce the amount of water entering underground coal mines was prepared. A review of engineering practices currently used by operating coal mines in the Appalachian region to prevent the movement of ground and surface water into active coal workings was conducted. Major emphasis was placed on the identification of the geologic and hydrologic con¬dition of the site, onsite inspection of the methods used and an evaluation of their technical and cost effectiveness.

Jan 1, 1981