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By Erik A. Munroe, Nelia W. Dunbar, Virginia T. McLemore

In New Mexico, there are at least 100,000 abandoned mine waste rock piles with widely ranging geochemical and mineralogical compositions. A geochemical and mineralogical study was implemented for five waste rock piles, some which contained sulfides, in the Hillsborn Mining District. Chemical and physical characteristics of mineral grains and their secondary mineral oxidation rinds were examined with the electron microprobe. Pyrite and chalcopyrite appear to be the most reactive to oxidizing conditions. Clays, iron oxide, iron hydroxide, iron sulfate, and primary texture rinds exist in the waste rock piles analyzed.

Jan 1, 2000

By William C. Beebe, Russell E. Martin

An account of driving and concreting two 900 m railroad tunnels for the Denver and Rio Grande Western Railroad under emergency conditions. Details the importance of on-site decision making by the Owner in completing the project successfully in record time. A general description of the geology and construction methods. The Thistle Drainage Tunnel drained water impounded behind the Thistle slide and serves as permanent diversion of the Spanish Fork River and Thistle Creek around the slide area. The project involved 684 meters of 5 m horseshoe tunnel, a 5 m diameter raised shaft and 23,000 cm of cut excavation.

Jan 1, 1985

By W. K. Summers

During the past few years monitoring systems have been installed to measure the effects of environmental changes on the ground-water resource. The design of a monitoring system depends upon the designer's perception of how the environmental factors merge with his perception of the ground-water flow system. The validity and representativeness of measurements made during a monitoring program depend upon the validicy of the designer's perceptions and concepts. To optimize the design of a ground- water monitoring program the designer should make preliminary measurements to confirm his assumptions.

Jan 1, 1985

By I. E. Odom

An electron optical and microprobe study was made to determine the physical and chemical nature of the silica minerals that occur as natural impurities in bentonite and montmorillonitic fuller&apos;s earth clay products (both granular and powder) and that occur in <10-µm dusts from plants that process these products. The purpose of the study was to determine if discrete "free" silica minerals, such as quartz, could be observed using SEM and EDS methods. No “free" silica minerals could be observed in the SEM images of the granular and powdered products, either among or on the surfaces of the particles. Also, no “free" silica could be identified by either SEM or EDS analyses of the dusts, even though quantitative X-ray diffraction analysis indicated that trace amounts of quartz occurred in all samples. It was determined that these quartz and other silica minerals were encapsulated or coated by montmorillonite. Vigorous washing, however, removed some of the clay coatings, so that small amounts of silica minerals could be seen by SEM and EDS analysis. It was found that all primary crystalline quartz grains in the bentonites have diagenetic overgrowths consisting of a mixture of montmorillonite, opaline silica and possibly microcrystalline quartz. Detrital quartz grains in the fuller&apos;s earth have thin diagenetic overgrowths of opaline silica, also containing montmorillonite. The clay encapsulation of the silica minerals in the products studied, as well as in the potentially respirable (<10-µm) dust produced during manufacturing of bentonite and montmorillonitic fuller&apos;s earth clay products, is considered to be an important factor influencing the potential health effects (e.g.. silicosis) of the contained silica. Even if clay dust containing silica should be inhaled, the montmorillonite encapsulating the quartz and other silica minerals would prevent direct contact of the silica with lung tissue. The clay encapsulation of quartz, as well as the highly hydroscopic nature of montmorillonite, may explain why not a single confirmed case of silicosis has ever been reported among plant workers in more than 65 years of production.

Jan 1, 1998

By A. Redfern, B. G. D. Smart

The ultimate objective of the development work presented in the paper is to devise an appropriate method for relating powered support specification to geological conditions and mining practice, thus enabling the longwall method of coalmining to be successfully implemented throughout the varied coalfields of the world. The paper begins with a review of various methods previously used to determine support rating, each method being analysed with regard to its source, the logic and theory which constitute the method, and subsequent recommendations. An alternative approach is then proposed, the Powered supports being considered to be one of three foundations, sharing load with coal ahead of the faceline which acts as another foundation, and the waste behind the supports which acts as the remaining foundation. The load/deflection characteristics of the coal and waste, which in turn are related to geological conditions and mining practice, are shown to affect the load transfer on to and hence the specification of the powered support. In particular the characteristic of the waste foundation is shown to be affected by the caving mechanism, an alternative form to that mechanism accepted for British conditions being proposed and designated "parting-plane-controlled" caving. A finite element solution for a beam on elastic foundations was used to translate the above concepts into numerical results, these results being compared with data from Indian and Chinese operating conditions. The Indian case study examines the effect of using a conventional chock type of support in a one-web back mode when mining towards a roof break generated ahead of the face, while the Chinese case study compares measured subsidence over a longwall with "blocky" roof conditions with the model results. The comparisons are encouraging, suggesting that the approach used is worthy of further development.

Jan 1, 1986

By K. A. Natarajan, M. K. Yelloji Rao

The electrochemistry of sphalerite and chalcopyrite was investigated under both open-circuit and applied potential conditions. Emphasis was placed on the selective dissolution of sphalerite from a mixture of sphalerite-chalcopyrite flotation concentrates as a function of applied potential, acid concentration, pulp density, and time. Morphological studies using a scanning electron microscope (SEM) were also carried out with chemically leached, galvanically leached, and unleached surfaces of sphalerite and chalcopyrite. Selective dissoulution of sphalerite could be achieved if the mixed chalcopyrite-sphalerite concentrate slurry was maintained at a negative applied potential of -0.4V (SCE). Probable mechanisms involved in the selective dissolution of zinc are disscussed.

Jan 1, 1990

By M. S. Prasad, K. J. Reid, M. P. Katsoulis

The State of Minnesota is interested in stimulating the development of clay resources and recently supported a two-year project to collect data on geological, mineralogical, processing, economic and environmental aspects of such potential developments. This paper presents the various process options adopted on bulk samples collected from the Minnesota River Valley area, which is a primary deposit and contains a major silica fraction. A standard test flowsheet involving degritting, dispersion. HGMS and cycloning was developed and for some samples yielded an acceptable filler grade product. Secondary streams containing relatively high grade kaolin but of coarse size were also obtained. Improvement in particle size distribution and in physical properties related to paper product specifications (brightness, viscosity) were obtained by size-reduction processes. Market and economic considerations for kaolin consumption in the upper Midwest are analyzed. Current markets for paper grade kaolin in Minnesota are briefly discussed.

Jan 1, 1992

By John T. McDonough

The Climax Mine of AMAX&apos;s Climax Molybdenum Division is currently producing approximately 34,000 tons of molybdenum ore per day from two underground levels (see Figure I), and initial design is underway for the next deeper (1200) level. The aim of this report is to present the methods of site evaluation used at Climax for cavability determinations and underground support design. Climax succeeds with its panel caving system of mining (Julin, 1973) (Figure 2) largely because of the presence of pervasive geologic structural discontinuities. The stockwork ore body at Climax was formed by the multiple intrusion of mid-Tertiary rhyolitic magmas into Precambrian granite, schist and gneiss, and the hydrothermal emplacement of molybdenite into the network of fractures that were generated during the forceful upward intrusion of magma. Subsequently, intrusive events that were more deeply seated refractured the overlying, ore- bearing stock and propagated a complex system of axial and radial fractures. Post-ore movement along the Mosquito Fault (Wallace, 1968) and its associated stranded shear zones further fractured the ore body and disordered the existent geologic structure. The result of these structural events is a brittle, crystalline ore body that is transected by a complex pattern of faults, shear zones, and joints that augment cave initiation and enhance comminution of the ore blocks. Generalizations can be made about the structural trends within the ore deposit (King, 1946; Kendorski, 1973), however, the intensity and orientation of geologic structure is by no means uniform throughout the ore body. The relative intensities of silicic and argillic alteration are also highly variable (Vanderwilt and King, 1955). As a consequence, no single rock-mass model suffices as a standard for mine design, and site characterization for cavability and support design is a continuous process.

Jan 1, 1977

By E. Sabah

A series of adsorption tests are carried out to understand the ability of cationic surfactants and metal ions to adsorb onto sepiolite. Adsorption tests conducted as a function of heat treatment reveal that sepiolite is rather conducive to the uptake of both organic and inorganic ions. An ion exchange mechanism between surfactant or metal cation and magnesium ion followed by chain-chain association is proposed to explain the incorporation of cationic surfactants into the structure of sepiolite.

Jan 1, 1998

By M. M. Hajdasinski

For decades, the internal rate of return (IRR) project-evaluation criterion has been under increasing criticism. Torries (1998a) defends the beleaguered criterion. He claims that, as a project-evaluation and ranking instrument, the IRR is as suitable as the net present value (NPV). Torries also maintains that using the IRR to rank projects does not require the incremental approach and introduces his own alternative ranking approach. This paper disputes Torries&apos; pro-IRR arguments and demonstrates that the IRR is a theoretically flawed and operationally dysfunctional criterion whose true meaning has persistently been misinterpreted. In a forthcoming paper by the author it will be shown that Torries&apos; IRR-based project-ranking approach is flawed as well.

Jan 1, 2000

By G. E. Jones, G. K. Hoffman

Two Sun Juan Basin studies were completed through the USGS National Coal Availability program. The study areas are in the northwest Bisti field (Fruitland Formation) and in the eastern Standing Rock field (Menefee Formation). In the Bisti and Standing Rock areas, the original coal resource5 are estimated at 4.66 and 3.1 7 Gt (5.14 and 3.49 billion st), respectively. The Bisti coal resources are greatly reduced by the Bisti-De-Nu- Zin wilderness area, which contains an estimated 1.13 Gt (1.25 billion st) of coal. Technological restrictions remove 32.5% from Standing Rock&apos;s original resource. Available resources are 60%. 2.79 Gt (3.07 billion st), of the Bisti original resource and 65%, 2.07 Gt (2.28 billion st), of the original Standing Rock resource.

Jan 1, 2002

By D. L. Schweyer, W. A. Munson, R. H. Hanewald

Discussed is the INMETCO processing of electric arc furnace (EAF) baghouse dusts from the specialty-steel and low-alloy industries. In addition, the INMETCO process has been modified to recover nickel, chromium and iron from many other waste materials including: •pickling solutions or filter cakes, •spent nickel and chromium plating baths, •carbon refractories from pickling tanks, and •superalloy wastes including baghouse bags. INMETCO is the only North American company presently capable of recycling nickel-cadmium batteries by high-temperature metals recovery. This process and the details of INMETCO&apos;s best demonstrated available technology (BDAT) test program are discussed.

Jan 1, 1993

By J. A. Herbst, S. L. Blust

Optimization of blasting, crushing, and grinding operations is filled with challenges. One of the more difficult tasks is accurately sampling and determining the size distributions of blasted and crushed materials at a reasonable cost. The task is difficult because of the large size of fragments and the tonnage involved. However, the size distribution measurements are necessary for models that predict the performance of mine-through-mill operations. This paper is concerned with the use of video sampling for this task at National Steel Pellet Company&apos;s operation in Keewatin, Minnesota Data gathering, data analysis, model building, and mine-to-mill simulation are all described.

Jan 1, 2000

By Anthony D. Hammond, Charles A. Kliche

A slope stability study for the Annie Creek and Foley Ridge Mines was undertaken to provide Wharf Resources, Inc. with a technical assessment of the stability of the slope for an overall pit slope angle of 60°. A rock analysis of the most critical and persistent combination of discontinuities was carried out using probabilistic methods. A detailed discontinuity mapping and assessment of the rock mass provided the orientation data used in this study. The orientation data were reduced and analyzed to identify the discontinuity sets. A statistical analysis provided information about the distribution of the data. A deterministic wedge stability analysis identified the critical combination of discontinuities; those with a low factor of safety were further studied using probabilistic kinematic and kinetic stability analyses. The results from this approach were used to obtain the reliability or probability of failure of the slopes.

Jan 1, 1988

By R. C. Oberth, C. F. Lee, E. M. Taylor

INTRODUCTION Underground siting of nuclear power stations is drawing increasing attention in various parts of the world. Scandinavian countries took the early lead in this field because of their experience in the design and construction of underground hydroelectric stations and industrial plants, and because they have near-surface rock formations which are ideally suited for hosting large underground caverns. The world&apos;s first underground nuclear facilities were built in Norway (Halden) and Sweden (Agesta) and were commissioned in 1959 and 1963 respectively. Figure 1 summarizes the main features of these and two other small-scale European facilities. (1-4) American utilities and regulators are also for a variety of reasons assessing the benefits and penalties of underground siting. A recent study by Sandia Laboratories (contracted by the Nuclear Regulatory Commission (NRC) focussed on identifying potential safety benefits of underground siting. (5) Although the study concluded that underground plants would have improved containment for some accidents, as well as better external protection, NRC, in assessing the overall benefits and penalties, decided not to impose mandatory underground siting for nuclear stations. In June 1976, the California Legislature enacted a law which directed the California Energy Commission (CEC) to examine the issues concerned with underground siting of

Jan 1, 1979

By J. T. Crawford

A comprehensive strategic-planning model was developed for the phosphate strip-mining and chemical operations at White Springs, FL. The computerized model covers orebody modeling, production simulation and financial analysis. The model has several innovative features, including the use of NPV techniques in orebody block economics, the adaptation of the floating-cone method to a floating template for generating dragline mining units automatically, the use of interactive graphics for designing mining units, and the use of a dragline move economics algorithm for the automatic scheduling of mining-unit assignments and moves. The simulation of chemical-plant production uses linear programming and concentrate inventory levels to control mine-operating schedules.

Jan 1, 1999

By M. Balakrishnan, K. A. Natarajan, J. M. Modak, J. S. Gururaj Naik

The ability of various fungal species isolated from gold mines to uptake gold and base metals such as zinc, copper, iron and lead from gold-process cyanide effluents was investigated. Under identical treatment conditions, different strains showed wide variations in their ability to take up gold and other base metals. Aspergillus terreus exhibited as high as a 60% gold uptake. Almost complete removal of zinc was possible with various fungi and with the yeast Saccharomyces cerevisiae. Studies at various metal concentrations showed a higher gold uptake from dilute solutions, and studies with Aspergillus niger showed that gold uptake by living cells increased gradually as the contact time increased. Metal uptake capacities between living and nonliving cells were also compared. A waste biomass (ABM- I), obtained from a fermentation industry, wasalso identified as having a high gold uptake capacity. At 5% (W/v) solids, ABM-I could efficiently remove up to 83% of the gold contained in an effluent solution within 24 hrs.

Jan 1, 1995

By Lijun Xu, Jan M. Mutmansky

The purpose of this research was to investigate airborne coal mine dust characteristics in order to assess the possibility of contribution of these characteristics to the incidence of coal workers&apos; pneumoconiosis (CWP). The characteristics studied included physical (mass concentration and size distribution), chemical (elemental composition), and mineralogical (quartz and kaolinite content) variables of the dust. The results are based primarily upon analysis of the characteristics of 99 impactor samples from 18 mines in seven states. Because the eight stages of the impactor span the range of dust sizes up to 20 microns, the characteristics analyzed should represent respirable dust characteristics well and also provide size-dependent representations of the characteristics. In general, the patterns of mass concentration and size distribution in the various mines studied were similar with mass concentrations being high downwind of the continuous miner. The concentrations and size distributions were more variable upwind of the continuous miner, apparently as a result of the variations in the dust conditions in the working section. Significant size effects on the elemental and mineralogical content are shown in the data. Concentrations of most of the elements decrease as size decreases. However, minerals content increases as the dust size decreases. Regional variations of elemental and mineralogical content are also significant. Quartz and kaolinite contents are small in regions with low incidences of CWP. However, the elements of Cu and Zn are high by comparison to their content in high-incidence coal fields and may have the effect of protecting against the disease.

Jan 1, 1991

By Fu Lizhu, Qiu Tingsheng

An application of water-system magnetizing technology for the mineral processing and hydrometallurgy is introduced in this paper. The water-system magnetizing technique flotation and cyanidation leaching test of vein-ore of gold-bearing and conventional technique flotation and cyanidation leaching of gold-bearing vein-ore was carried out. The best condition of water-system magnetizing was determined by orthogonal test. The results have shown that the water-system magnetizing technology may increase the efficiency of flotation and cyanidation leaching for gold. The industry-scale test results also show that it can increase flotation recovery by 1-3% and leaching extraction by 3-5% of a gold-bearing vein- ore. The interaction of magnetizing water-system with minerals was carried out and initially investigated.

Jan 1, 1995

By J. F. Able, F. Djahanguiri

The US Bureau of Mines conducted research on underground stope leaching of metalliferous ores. Leaching underground would minimize the environmental impact of ore processing on the surface and would maximize minable reserves. An important aspect of this process is the minimization of pregnant solution losses and groundwater contamination by leach solutions. Bulkhead design and construction are important issues for solution control and stope-leaching economics. A reinforced-concrete bulkhead was designed, constructed and tested for solution control in an underground mine near Idaho Springs, CO. This paper presents the bulkhead-design methodology and construction procedure.

Jan 1, 1998