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By F. Michael Wahl

With the exception of reports on commercial deposits of kaolin, fuller's earth, and other specialty type clays, there is little published information on the extent, properties, and potential uses of the clay resources of Florida. Recent studies by the Florida Bureau of Geology in cooperation with the University of Florida and the U.S. Bureau of Mines have proven the existence of two extensive Miocene clay deposits, one in peninsular Pinellas County and the other in southeastern Charlotte County. Drilling and subsequent testing of the clays from these deposits indicate their potential for economic development. Both deposits consist of montmorillonite type clays, have an average thickness of 25 to 35 feet, and are overlain by unconsolidated Pleistocene sediments. Preliminary firing tests indicate that the clays from Pinellas County are a potential raw material for lightweight aggregate production. The clay has good bloating characteristics across an acceptable temperature range with a resultant aggregate density of less than 1.00 specific gravity. The clays from Charlotte County have poorer natural bloating characteristics but might well be used after treatment or with additives. The economic potential and locations of both deposits emphasize the need for locating similar clay resources in the state that might have economic potential so that land use planning and subsequent urbanization will not prohibit their development.

Jan 1, 1972

The 1997 Rapid Excavation and Tunneling Conference (RETC) was held at the Mirage Hotel, Las Vegas, NV. The RETC is a biennial event jointly sponsored by SME and the American Society of Civil Engineers (ASCE). Conference attendance was 573 members, nonmembers and students, an increase of seven attendees from the 1995 conference in San Francisco, CA. Exhibitors occupied 51 booths at the Las Vegas RETC. The 1997 conference encompassed 58 presentations in 15 sessions. Participants were given details on achievements and advances that have resulted in new design solutions, alternative work practices and increased productivity within the industry. The page at the end of this article tells how to get your copy of the RETC proceedings, either hardbound or on CD-ROM. Or, if you wish, for the first time a CD-ROM is available with the complete RETC proceedings from 1972 to 1997. This two-disk, archival volume has key-word search capability, is in portable file format and is compatible with PC and Macintosh platforms. RETC program sessions included design and planning, ground support, tunnel boring machine (TBM) case histories, conventional excavation, new technology, difficult ground, geotechnical, shafts and raises, future/special projects, new Austrian tunneling method, international projects, soft ground case histories and water and gas. What follows are highlights of some of the RETC presentations.

Jan 1, 1997

By Joseph A. Dos Santos

The Expanded Conveyor Technology, a rationalization of the conventional conveyor technology, allows us to apply the theory and principles beyond the current (perceived) limits. This was first prompted by the writer's advancements in Sandwich Belt High Angle Conveyors. The introduction defines the Expanded Conveyor Technology and outlines the range of applicability for the wide variations in conventional and non-conventional conveyors. The writing deals with the theory and design of sandwich-belt, high-angle conveyors in the context of the Expanded Conveyor Technology, including the equations of friction, hugging pressure and the continuity of hugging principle; curvature constraints and criteria for tension, curvature, trough, and belt construction; and drive and tension analysis, load sharing and traction, including "derived load equivalents."

Jan 1, 2000

By J. Peck, M. J. Scoble, C. Hendricks

This paper is based on field studies in North American surface mines. The work involved the adaptation of microprocessor-based instrumentation to monitor various operating parameters on-board rotary blasthole drills and mining shovels. Following a review of instrumentation and monitoring methodology - drawing on experience gained under field conditions-the paper will focus on the application of monitoring technology within the framework of an Integrated Equipment Monitoring System. Such a system will permit real-time performance evaluation of key equipment involved in surface mine production. Drill performance monitoring has been demonstrated through work to date, to provide significant input into blast design, reserve estimation, mine planning and production control processes, through an improved facility for ground characterization. Monitoring excavation equipment has been proven valuable in assessing how effectively the input from drill monitored data has been used in the evolution of blast designs. This specifically refers to assessing blast efficiency through measuring associated levels of excavator performance in relation to muckpile characteristics. The medium-term goal of equipment instrumentation and monitoring has been to assist mines in optimizing the overall rock breakage and handling process. Based on the reported results, this has been accomplished. Long-term efforts now concern using a greater understanding of equipment performance and response to varying operating conditions as a foundation for the implementation of mining automation.

Jan 1, 1993

By H. J. Marais, P. C. van Aswegen

The Biological Oxidation (BlOX®) Process for the treatment of refractory gold ores was commercialized in 1988. During the last decade, the technology has developed into a mature, commercially viable process, with five additional operations commissioned, including operations at Sao Bento in Brazil, Harbour Lights and Wiluna in Australia, Ashanti in Ghana and Tamboraque in Peru. With ongoing development, the efficiency and cost effectiveness of the process have both improved, making it an attractive alternative to conventional refractory treatment processes such as roasting and pressure oxidation. The bacterial culture is robust and can withstand the normal fluctuations experienced on an operating plant. The plants are simple to operate, making it ideal for remote areas. The scale-up potential of the process has been proven, and it can be applied to large refractory ore bodies. The process is environmentally friendly. Neutralization of plant effluents produces precipitates that comply with the most stringent environmental regulations.

Jan 1, 2000

By Carl-Eric Dr. Nilsson

Energy cost for mine ventilation in Sweden is high, especially during winter time when air must be heated. This paper presents the result from a project entitled ventilation-as-required. The term ventilation-as-required means that the required volume of fresh air should be distributed only to such areas, where mining work is going on and to be reduced to a minimum in the rest of the mine. Ventilation-as-required is a monitoring system that controls the operation and capacity of the fans and measure the air pollutant gases, i.e. carbon monoxide, nitrogen and sulphur dioxide at strategic points. It is an active system that responds when equipment is under operation. MITU proposed in 1991 a project to develop a ventiation-as¬required system and such components as transmitters and receivers for the communication between the equipment and the fans. The mining companies, Boliden Mineral AB, LKAB, Outokumpu and Ammeberg Mining Corporation joined the project and have financed a joint research and development programme supported with a grant from the Swedish Government through NUTEK. MITU proposed a second project in 1992 to the mining companies to develop an improved "intelligent" fan for scope ventilation. Boliden Mineral and LKAB joined the project and have financed a joint research and development project supported by the Swedish Government through NUTEK. The Government even made a commitment to support the investment of the first 50 fans ordered with a grant of 25% of the investment cost. The result from projects show that the target set up in the plans is more than achieved, with an energy reduction that exceeds 30% compared to previous consumption. No environmental influence due to reduced ventilation is observed in the stope when work is under progress. Dilution of exhaust gases from diesel fuel decreased from 6.000 m3/L consumed diesel fuels to 3,600 m3/L. The automatic data processing and sensor system is even increasing the security of the work so that it can be done under safer environmental conditions.

Jan 1, 1995

An atomic force microscopy (AFM) has been applied to study the adsorption of potassium amyl xanthate (PAX) and potassium ethyl xanthate (KEX) on arsenopyrite surface in solutions. AFM images show that the collectors adsorb on arsenopyrite surface in patches at pH 6. Increasing the chemical dosage will increase the adsorption density of the patches on mineral surface. The increased probe-arsenopyrite adhesion measured in PAX solutions at pH 6 is attributed to the adsorption of the patches, suggesting the hydrophobic nature of the patches, which is likely the oily dixanthogen. It is also found that arsenopyrite is reactive in water in the presence of air. At a high pH with the addition of Ca(OH)2 the adsorption of collectors on arsenopyrite is greatly retarded or depressed because the mineral surface is coated by a lot of precipitates, which is hydrophilic in nature as shown by the measured strong repulsive probe-arsenopyrite detachment force. The findings confirm that the flotation behavior of arsenopyrite in xanthate solutions is very similar to that of pyrite.

Feb 27, 2013

By Thomas R. Yanske, Jonathan E. Carmack, Lyndon M. Clark

In order to maximize the extraction of high grade pillars at The Doe Run Company, artificial pillars are created using cemented rock fill (CRF). CRF pillars aid extraction of pillars in two ways. One is to offer back support for the immediate area where pillars are being extracted. The second is to increase the post failure residual strength of pillars surrounded by backfill. The CRF is produced using a combination of minus 1.0 m run of mine (ROM) rock and minus 5 cm crushed rock. Depending on the operation the CRF slurry is either produced in an underground or a surface batch plant. The slurry and rock are transported to the fill area by truck where they are mixed and placed in 1 m lifts. To reduce the amount of CRF needed, fill fences are constructed around the perimeter of the CRF pillar. Within these fences ROM CRF is placed in lifts until within 0.6 m of the back after which minus five centimeter CRF is slung tight to the back utilizing slinger trucks. In constructing these artificial pillars a number of set procedures have been established to ensure that the work is done both properly and safely.

Jan 1, 2001

By A. B. Samaddar

A prototype automated mapping and spatial information management system has been developed, and illustrates how a powerful map manipulation capability and a comprehensive display system can be combined using both raster and vector mapping: The concept of a mapbase and information retrieval mechanism, query language as well as text and graphical menus, is introduced. The Geographic Information System (GIS), which has been built around a system for storage and retrieval of spatial and textual data, allows interaction with geographic space represented on a displayed map. The prototype is demonstrated using maps and information of an open pit mine.

Jan 1, 1989

By T. J. Driscoll

The effect of coatings on the incendive properties of aluminum alloy 6061-T651 in air-6.4%CH4 was studied for collisions between rusted steel and both uncoated and coated projectiles with incident energies as high as 300 J (220 ft-lb) and velocities as high as 200 m/s (660 fps). These conditions were intended to simulate the rough handling of equipment in coal mines. The ignition probability using uncoated alloy projectiles increased with increasing relative humidity and appeared to be influenced by atmospheric ozone content. The incendive properties of both the uncoated and coated alloy depended on the type of rust used, but the dependence of the coated alloy was very different from that of the uncoated alloy. A number of coatings developed in the last 25 years were found to offer protection from ignition and to remain largely intact for occasional collisions or collisions randomly distributed over the coating surface, but probably not for repetitive collisions at any given point on the coating. These protective coatings utilize a hard anodized aluminum alloy surface coated with one or more layers followed by heat treatment of the coating. Coatings containing Teflon and MoS2 and thicker than 50 µm (2 mils) appear to be most effective.

Jan 1, 1987

By Donald J. Olson, Thomas J. Lutzenberger, John Ramage

The North Shore Inline Interceptor, Phase IA tunnel is a 8,550-meter (28,000-ft) interceptor tunnel currently being constructed by Traylor Bros./Frontier-Kemper, Joint Venture, using a 9.8-meter (32-ft - 4-in) diameter Robbins tunnel boring machine (TBM). This tunnel is being driven in Silurian age dolomite approximately 91.5 m (300 ft) below ground surface. Significant water inflows were encountered when the tunnel drive penetrated the thinly-bedded Waubakee Formation. Flow increases approaching 0.75 cu m per min per 30 m of tunnel (200 gpm per 100 ft) have occurred in this formation. After driving approximately 2,285 m (7,500 ft) of tunnel (200 m full face in the Waubakee Formation), total flows exceeded 12 cu m per min (3,200 gpm) with about 5.7 cu m per min (1,500 gpm) entering the tun¬nel from the 200 m (600 ft) of exposed Waubakee Formation. Additional water control measures consisting of increased pumping capacity, increased water treatment capacity, surface grouting ahead of the tunnel, grouting ahead of the tunnel face and panning to improve the working environment for installation of tunnel support, were implemented to deal with the large water inflows. Currently (January 24, 1989), 3,400 m (11,000 ft) of tunnel has been driven, total water inflows are in the range of 11.7 cu m per min (3,100 gpm) with only 6.8 cu m per min (1,800 gpm) inflow from about 1,220 m (4,000 ft) of tunnel driven full face through the Waubakee Formation.

Jan 1, 1989

By A. G. Fabbri

This paper aims at the application of quantitative criteria for evaluating the mineral potential of square cells representing areas in terrains being explored at a reconnaissance level. The assumption is made here that the evaluation methods used by an expert economic geologist can be organized into geological models for establishing associations within imaged areas, that correspond to pixels with similar characteristics. UTM-registered multiple data sets have been constructed which include seasonal LANDSAT 2 and 4 images, SEASAT scenes, selected airborne radar images, digitized aeromagnetic, gravity, bedrock geology and topographic elevation maps. The area of interest is located in the Bathurst Inlet, District of MacKenzie, N.W.T., where a preliminary mineral potential evaluation was performed by the Geological Survey of Canada to assess its suitability for a national park. The multiple data sets described in this paper can be used for many studies at different resolutions, for comparing processing methods in remote sensing and, most importantly, for evaluating the physical and spatial relationships between the different images in registered data sets.

Jan 1, 1989

By A. R. Wagner, E. Berkman

The use of high-resolution seismic surveys in coal exploration and mine development is becoming established as a standard technique in the industry. Their most significant contribution is in the effectiveness of reducing the number of core holes needed to understand the complex geological nature of coal by identifying geologic faults and mapping coal seam continuity and relative coal thickness. With these goals in mind, a high-resolution seismic survey was conducted in 1980 in the Wasatch Plateau coalfield of Utah. As a result of the success of this initial survey, numerous additional surveys have been performed over the past six years.. The interpretations of these subsequent surveys have led to the location of faults, fluvial channel sandstones, and coal thickness trends. This paper presents a review of high-resolution seismic technology as applied to coal exploration followed by three case histories, two of which illustrate the utility of the technique related to coal thickness determination and faulting and one that serves as an example of pitfalls in interpretation.

Jan 1, 1987

By J. W. Mahar, E. J. Cording, F. L. Gau

INTRODUCTION The Washington, D.C. rapid transit system (METRO) when completed will consist of 98 miles of double track rail. Fifteen miles will be tunneled in rock and 12 large underground rock chambers will be constructed at station locations. The University of Illinois is under contract to Metro to provide observations and instrumentation services in the initial phase of construction. The work is coordinated through DeLeuw, Cather & Co., the General Engineering Consultant to Metro. The program is designed to monitor construction conditions as well as to provide information useful for the design of future rock tunnels and rock chambers in the Metro system. This paper presents the results of observations in the rock tunnels constructed to date. Most of the observations are in a 5000-ft-long, 30-ft-wide, double track tunnel in downtown Washington, D.C. Observations were also made in single track tunnels, shafts, enlargement areas, and pilot tunnels, and are being made in a large rock chamber 700 ft long, 76 ft wide, and constructed at shallow depth in a schistose gneiss. One of the major objectives of the observational program was to determine the orientation and character of joints and shear zones and to evaluate their effect on support requirements for various tunnel orientations and configurations. The consistency of geologic features throughout the Washington area has made the results of the initial study applicable to evaluation of support requirements on future tunnel contracts. The first section of this paper summarizes the geologic conditions in the tunnel and their effect on overbreak and rock movement.

Jan 1, 1997

By M. Leduc, M. Backens, M. E. Smith

An emerging technology for sustainable development in mineral development, tailings co-disposal™ is a means to dispose of conventional mill tailings within the void space of a waste rock dump. This method, while not applicable to all tailings systems, can offer a significant reduction in short-term and long-term environmental liability, land disturbance, closure costs, and negative public image. The concept is to dispose of the tailings simultaneously with the waste rock or leach ore, controlling the ratio of tailings to coarse material such that the resulting dump is stable both physically and chemically. The resulting co-disposal dump can be as safe as a conventional waste dump. In the case of alkaline tailings in a potentially acidic waste dump, the acid production can be buffered or slowed.

Jan 1, 2004

By Donald W. Gentry

Mine valuation is a multifaceted, interdisciplinary process by which the economic viability of an old, existing, or new mining property or venture is determined. The problems associated with arriving at a representative and accurate value for a mining property are complex and numerous, and the procedures utilized in determining these values vary from simple, back-of-envelope calculations to sophisticated mathematical manipulations requiring computer modeling and analysis. Regardless of the complexity or the degree of sophistication associated with any particular project, the evaluation process must ultimately provide management with two basic types of information. First, the evaluation process should indicate whether or not the mining project is economically viable after careful consideration of all engineering, environmental, geologic, and other variables pertaining to the project. Second, the evaluation process should provide management in- formation on the relative attractiveness of the project when compared to other alternatives. In some cases, it may be extremely difficult to supply this information for a project directly. Nonetheless, the evaluation process should and must present all information necessary in a format which can be incorporated into the decision-making process as expeditiously as possible.

Jan 1, 1979

By G. Fehr, B. B. Panda, R. Bansberg, K. Arnold, T. Freiman

To evaluate the potential for process solutions to contaminate groundwater outside of the area of the Oxide Pit, it is necessary to predict the ultimate maximum pit lake elevation once pit-related mining activities have ceased. A water balance model was developed based on the existing pit geometry, the groundwater flow equation, and assumed hydrologic input parameters. The model assumed that at any point in time, total inflow into the system (i.e., direct precipitation, surface water and groundwater) minus outflow from the system (evaporation from the lake surface) was equal to the change in the pit water volume. The pit lake depth over time was predicted by assuming a succession of steady- state water balance conditions over short time increments. An analytical method using a spreadsheet and computer model was employed in this study to model the filling of the lake in the Oxide Pit. A sensitivity analysis was performed to evaluate uncertainty associated with the input parameters in the model. The sensitivity analysis indicated that the model was most sensitive to values of precipitation and evaporation and to the static water table.

Jan 1, 2003

By Robert Seal, James J. Rytuba, Michael P. Hunerlach, Roger Ashley, Dean Enderlin

Cessation of open pit mining in 1996 at the McLaughlin hot-spring type gold deposit has resulted in the development of two pit lakes that will be managed as permanent lakes with a total storage capacity of 10,000 acre-feet. The south pit lake developed from alkaline ground water infiltration and had an initial pH of 7.2. It contained high concentrations of boron and chloride, indicating that it consisted of a mix of meteoric and evolved connate waters. Numerous carbon dioxide gas vents were present initially in the shallow south pit lake, but as the pit lake increased in depth, gas venting ceased and carbon dioxide is retained in the lower layer of the chemically stratified lake. Continued increase of dissolved carbon dioxide in the lower layer increases the potential for a limnic eruption. A chemocliie occurs at a depth of 47 m. The upper layer of the lake has lower pH, temperature, and conductivity than the lower layer. Effluent from ore and waste rock piles directed into the south pit lake has contributed to high levels of antimony, arsenic, cobalt, copper, mercury, nickel, and zinc. Iron oxyhydroxide is abundant in mine effluent that enters the pit lake and adsorption onto this phase has lowered the arsenic and antimony concentrations. The north pit lake formed primarily from winter surface runoff. The acidic water, pH 4.56, initially had high concentrations of cobalt, mercury, and nickel derived from weathering products of pyritized serpentinite and shales. Buffering by wall rocks has established a slightly alkaline pH of 7.62. The concentrations of trace metals in the north pit lake have substantially decreased due to continued dilution of the lake by surface runoff and remediation of parts of the pit walls that have been covered by backfill.

Jan 1, 2000

By Frank E. Kottlowski

Widespread high-calcium (HC) limestones in New Mexico and adjoining areas, are low in magnesium, but some units include shale interbeds that would be deleterious for usage in sulfur removal. In southwest New Mexico, southeast Arizona, and adjoining parts of Mexico, limestones in the thick Mississippian Escabrosa, Pennsylvanian-Permian Horquilla, and Cretaceous U-Bar units are HC as are strata in the Mississippian Lake Valley, Pennsylvanian formations, Permian Hueco, and parts of the Permian Capitan Limestone of south-central and southeast New Mexico and west Texas. In north-central and central New Mexico, many limestones in the Pennsylvanian Madera Formation are HC as are some of the Cenozoic travertines. In northwest New Mexico, where the present-day mine-mouth coal- fired power plants occur, there are no HC limestones, but to the north in southwest Colorado some beds of the Mississippian Leadville Limestone and Pennsylvanian Hermosa Formations are HC. HC limestones considered contain at least 95 percent calcium carbonate and less than 3 to 5 percent magnesium carbonate. Limits for other impurities are alumina, 1 percent; silica, 2 percent; sulfur 0.05 percent; phosphorous, 0.02 percent; and iron oxide, about 1 percent. Chemical and physical requirements differ slightly depending upon the ultimate use.

Jan 1, 1995

By M. S. Kabibwa, E. K. C. Chanda

In planning for the future, Nkana Division deepened the Mindola sub-vertical shaft which was commissioned in 1994 in order to access the 30 Mt of ore between 1274 and 1570 m levels. The Nkana Synclinorium which is estimated to contain 250 Mt of ore is being accessed from the vicinity of Central Shaft. These areas are being planned with the intention of maximizing the use of computers in geological modelling and mine design so as to overcome the inadequacies of manual planning techniques. As a result, there is an increased demand for quality output from the computerized mine planning system the division has been developing over the last few years. A new workstation comprising the Hewlett Packard HP 71 51100 MHz and a CRX graphics monitor was acquired in 1995 together with the LYNX (version 3.09 and version 4.0) Mine Modelling System. Currently the workstation is being used for geological modelling and mine design for the Zerofold at Central Shaft and the Mindola mining at depth project. AutoCAD and Mine Works Planner have been added to the sys- tem configuration. Mine Works Planner is likely to replace Lo- tus123 for mine scheduling tasks. Computer applications in the area of mine planning at Nkana has led to considerable time savings and improved efficiency in areas formerly performed manually and has allowed speedy processing of data that would otherwise have proved too time consuming. Nevertheless, a lot of work still needs to be done in the areas of geostatistics, stope design and financial modelling of mining options. For the foreseeable future computer based planning will operate parallel to manual methods until such a time as sufficient personnel are proficient in the use of computer systems. This paper describes the program of computerization at Nkana Division, reviews current applications and the benefits and experience gained and discusses the promise of current and future developments.

Jan 1, 1996