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By James P. Connell

The Montana Operations of the Anaconda Company constitute an integrated, though geographically separated, non-ferrous metal production complex. The mines are located at Butte and consist of one large open-pit mine, two small underground mines, a precipitation plant for both underground and pit-dump leach water, and the Weed Copper Concentrator. The smelter, located at Anaconda, Montana 25 miles to the west, processes all Butte copper shipments as well as copper materials from both Anaconda and private mines. Copper and zinc are refined at Great Falls, Montana, 165 miles to the north. Other facilities developed over the years include the Anaconda Forest Products Division, the Butte, Anaconda, and Little. Chicago Water Companies, and the Montana Hardware Company. Data processing for these operations has been performed on an IBM 360 Series, Model 30 computer, utilizing a Disc Operating System. This was replaced in September 1970 with a 360 Series, Model 40 128K unit. In addition, some data processing is also done for Anaconda Company operations located at Britannia Beach, British Columbia; Columbia Falls, Montana; Yerington, Nevada; and Twin Buttes and Tuscon, Arizona. The material under discussion in this paper will be concerned primarily with the mining operations at Butte.

Jan 1, 1970

By John D. Nelson

Unprotected uranium mill tailings impoundments can pose a significant risk to nearby inhabitants and the surrounding environment in the event of a prolonged or catastrophic release of contaminants contained in the tailings. As a result of this potential, reclamation plans for such facilities must include engineering designs to protect against disruption of the tailings and the potential release of radioactive materials. The goals for such engineering designs should be to provide overall site stability for long-term periods with no need for planned ongoing maintenance and to provide a repository for the tailings that will not place a burden on future generations. Although the goal is to provide a maintenance-free system that does not require monitoring, it must be recognized that some period of surveillance would be reasonable. The surveillance period could be relatively short and only needs to assure with reasonable confidence that the reclamation scheme that was implemented is functioning adequately. An investigation was conducted by Nelson, Volpe, Wardwell, Schumm and Staub (1983) entitled Design Considerations for Long-Term Stabilization of Uranium Mill Tailings Impoundments (NUREG/CR-3397). This report assesses the degree of confidence with which long-term reclamation plans can be expected to remain effective over specific periods of time, and to assess the additional effort required to extend the design period from one long-term period to a longer one. This paper presents a summary of that investigation and discusses some of the important conclusions.

Jan 1, 1984

By Nawal Kishore, Nilesh Pratap Singh, Amit Kumar Verma, Vikram Seervi

In India, despite its natural abundance, demand for coal exceeds its countrywide supply due to failure to achieve high production targets, especially in opencast mines, which are responsible for 94.98 percent of total raw coal production in the country. Employment of technological solutions, such as surface miners, is key to achieving higher coal production and productivity in an environmentally friendly manner, especially in populated areas adjacent to the mining zone. This technology eliminates blast hole drilling, blasting and primary crushing units, thus reducing related environmental hazards like ground vibration and fly rocks.

May 1, 2023

By Christopher Mark

Horizontal stresses are caused by global plate tectonic forces. During 1995 alone, they were largely responsible for closing two U.S. longwall mines. This paper presents six case histories from Pennsylvania, West Virginia, Kentucky, and Alabama. In each case history, a mine encountered roof falls or difficult ground conditions in the headgate, caused by horizontal stress concentrations. The problems are detailed, and the control measures adopted are described. In most cases, nearby longwall panels without stress concentrations were trouble-free. The paper also discusses detailed measurements made at two adjacent Pennsylvania longwalls. One headgate was oriented to avoid a horizontal stress concentration, and the other was not. Eliminating the stress concentration dramatically reduced roof support loads and roof deformation. The paper concludes that proper panel orientation and sequence is the key to maintaining headgate ground control. The optimum orientation is not parallel with the maximum horizontal stress, as previously thought, but rather 20° in the stress shadow of the gob. Other stress control techniques, including artificial support, are briefly discussed.

Jan 1, 1997

By George L. Atwood

The Monsanto Company's Henry Mine is located 17 miles northeast of Soda Springs, in the southeast corner of Idaho. Ore being mined is phosphate rock which lies in the Permian Phosphoria formation. The ore is the raw material for Monsanto's three furnace elemental "P" plant near Soda Springs. The finished product from the furnaces is elemental phosphorus which is subsequently used in the manufacture of detergents, food preservatives, fire retardants and other consumer items. Mining is by open pit methods using 0-9 crawler tractors to rip and push-load rubber tired scrapers in stripping and mining operations. The equipment spread consists of six D-9G crawler tractors, four Caterpillar 6578 scrapers, eight Euclid S-24 scrapers, one Reich T750 drill and one Caterpillar No. 16 patrol plus various support equipment. Stripping is performed on a 12-month basis, two shifts per day. Mining is performed mainly in the summer months on a one shift basis. The hauling season begins May 15 and ends November 1 due to freezing weather and snow conditions. Annual production is 1,000,000 tons of phosphate rock and 2,500,000 to 3,000,000 yards of stripping. Stripping, mining and hauling is performed for Monsanto by Dravo-Soda Springs, a mining contractor. Dravo-Soda Springs owns, operates and maintains all equipment used in stripping, mining and hauling. The contractor is paid for stripping by the bank yard and for ore mined and hauled on a tonnage basis. The Monsanto elemental phosphorus plant began production in 1952 with ore being trucked to the plant from the Ballard Mine. Haulage was over public roads in 15, 24-ton semitrucks. A private haul road was constructed from the Ballard Mine to the Monsanto Plant in 1958 and 1959 to accommodate trucks with two twenty-yard trailers. This 11/ mile road was first used in the 1959 hauling season. In 1965, five new Kenworth tractors with two, 'forty yard trailers were introduced into the haulage system. These units carried 120 ton payloads and were used until

Jan 1, 1972

By F. J. Sotillo

Mining in Peru is mainly concentrated on metallic and polymetallic ores of gold, copper, lead, zinc, silver, tin, iron, etc. However, little has been done to develop extensive and rich non-metallic or Industrial Minerals deposits with the exception of some silica and phosphate deposits. This paper presents the characterization and metallurgical studies for the development of a feldspar deposit. These studies showed that the special characteristics of the ore, such as high porosity, high Al2O3 content, low clays content, and sized material allowed us to obtain commercial products applying relatively simple and low cost concentrating unit operations. The characterization studies showed that the feldspar products contained no quartz and about 90% of albite (NaAlSi3O8). The 14x40-mesh size fraction product analyzed 5.91% Na2O, 22.56% Al2O3, 65.73% SiO2, 0.65% K2O, 6.50% CaO, and 0.40% Fe2O3; whereas, the 40x150-mesh size fraction product analyzed 6.22% Na2O, 24.30% Al2O3, 60.80% SiO2, 0.91% K2O, 7.06% CaO, and 0.54% Fe2O3. These products could be used for manufacturing glass, ceramics, refractory, and filters in different applications. In addition, Middlings, could be used as insulation material due to its porosity (bulk density of 0.828 Kg/dm3), analyzing 4.46% Na2O, 15.7% Al2O3, 67.2% SiO2, 2.57% K2O, 3.94% CaO, and 4.24% Fe2O3. The material showed a sphericity of 0.77, a roundness of 0.68, and acid solubility of 13.3025% on only washed and 2.72% effective for clean material suitable for use in these applications. No selective accumulation of the valuable mineral was observed at any specific size fraction. However, iron and titanium bearing impurities trended to concentrate in fine fractions (minus 70 mesh -212 µm-). Metallurgical studies demonstrated that this feldspar ore required sizing at 14x40 mesh and 40x150 mesh to render commercial products. In the case of the 14x40-mesh size fraction, the process involved magnetic separation, gravity separation, and flotation for feldspar (direct flotation) using a blend of primary and condensate amines. However, the reverse flotation for mica-biotite and iron bearing minerals was also possible using petroleum sulfonate. The metallurgical process for the 40x150-mesh size fraction required magnetic separation and reverse flotation of iron and titanium bearing minerals, the feldspar being reported in the sink material. Commercial products from this feldspar deposit for glass, ceramics, refractory, and filtration; and for the manufacturing of insulation material were obtained.

Feb 23, 2014

By Van Price

Some technical developments of the National Uranium Resource Evaluation Program which are of general application in geochemical exploration are being studied. Results of stream water and suspended and bottom sediment analyses are compared for an area near Williamsport, Pennsylvania. Variations of uranium content of water samples with time in the North Carolina Piedmont are seen to correlate with rainfall. Ground water samples from coastal and piedmont areas were analyzed for helium. All media sampled provide useful information when properly analyzed and interpreted as part of a total geological analysis of an area.

Jan 1, 1979

By K. V. Raj

"The development and advancement of computational fluid dynamics (CFD) has made it possible to better understand pollutant flow and distribution in deep open pit mines. Open pits located at higher latitudes, especially in the Arctic and sub-Arctic, face a unique problem due to atmospheric temperature inversion, which is prevalent during much of the winter. A three-dimensional CFD model of an actual open pit mine in the Arctic was developed to analyze the problem of pollutant growth during inversion, and mitigation of the pollutants through improved ventilation schemes. Due to the availability of mine-specific data, such as contaminant concentrations and coordinates of sampling locations, the actual 2013 pit geometry was used for model validation Concentrations predicted by the selected realizable ?-e turbulent model are compared to measured pollutant concentrations at the open pit. Pollutant concentrations at selected locations showed differences, but remained within the same order of magnitude in most cases. INTRODUCTION Computational fluid dynamics (CFD) has emerged as a useful tool for ventilation modeling in underground mines (Edwards and Hwang 1999, Purushotham and Bandopadhyay 2009, Wala et al. 1998, Xu et al. 2011). Application of CFD in open pit mines has been limited, however, since most open pit mines located at lower latitudes do not encounter considerable ventilation problems. Open pits located at higher latitudes, especially the Arctic and sub-Arctic, face a unique problem due to atmospheric temperature inversion, which is prevalent during winter. A number of Russian researchers have tried to understand the air inversion and resulting pollutant transport problem by modeling air flow phenomena in open pit mines (Baklanov and Burman 1996, Baklanov 1984, Baklanov 1995, Belousov 1985, 1989, 1995). Much of their work, however, was based on numerical models and methods of finite difference. Baklanov (2000) applied a modified ?-e and a ?-l CFD model to air flow phenomena on various terrains. More recently, Choudhury (2011) used the COMSOL CFD package for modeling pollutant transport for an idealized open pit mine. Collingwood et al. (2012a, 2012b) used a two-dimensional model for fluid flow and contaminant transport at an Arctic open pit mine. The authors have also previously presented work on CFD modeling of an actual open pit mine at high latitude (Bandopadhyay et al. 2014, Raj et al. 2015a). However, the CFD work done by the above-cited researchers lacked model validation with field-measured data. Validation of a developed model is important in assessing the quality and accuracy of the predicted results. In general, experiments are done numerous times in controlled environments to assess the validity of collected data. There are two types of assessments used in CFD simulations: (1) verification and (2) validation. Model verification is checking the accuracy of the computer codes during the implementation phase of a real-world problem, within the specific limits of accuracy (Oberkampf and Trucano 2002). Since, the pollution transport model presented in this paper used the commercial ANSYS-FLUENT CFD package, verification is not needed as the program has been tested widely, and verified numerous times."

Jan 1, 2016

By Subhas G. Malghan

Feldspathic deposits occur widely throughout the United States, but North Carolina, California, Connecticut and South Carolina accounted for over 80% of the total domestic feldspar output for the year 1973.1 Pegmatites and granites constitute the major feldspar reserves of the United States,2 and in addition, feldspar is produced as a by-product by firms whose major products are spodumene and mica.3 Feldspar is concentrated by hand-cobbing and flotation; the latter forms the major method of separating and concentrating feldspar. Feldspar flotation is practiced in the United States, Mexico, Finland, Norway, West Germany, Japan and the USSR. According to the U. S. Bureau of Mines estimates, the production of feldspar in the United States and rest of the world were 704,000 tons and 2,514,000 tons respectively. Feldspar is principally used as a flux in making glass, pottery, porcelain, enamel,-tile and other ceramic products. In recent years, the domestic feldspar industry is faced with a number of problems. As a result of increased cost of energy and the introduction in 1972 of new legislative programs relating to air, water, and noise pollution, land-use restrictions, and mined-land rehabilitation, the production costs have increased. Apart from the increased cost of operation, an operational problem exists with the feldspar producers in North Carolina, especially those in the Spruce Pine area. This problem is concerned with the use of hydrofluoric acid in the feldspar flotation. Feldspar producers in Spruce Pine, North Carolina have been discharging process waste water into the North Toe River. The mill waste water contains active fluoride ions. Fluoride in excessive concentrations is undesirable in waters used for drinking. It is stated that water

Jan 1, 1976

By R. R. Klimpel

The process of flotation is an extremely important solids separation technique employed in a wide variety of industrial process applications. Froth flotation is practiced in the coal industry to recover fines produced during the mining and cleaning of coal. A recent review article by Aplan (1) covers the processing variables encountered in the flotation of coal and the variety of chemicals and operating conditions which affect recovery. Numerous engineering and scientific studies have been performed with the goal of providing semifundamental laws of flotation behavior for improved screening of flotation chemicals, better equipment scale-up factors, etc. Often the results of such work are expressed in the form of mathematical models (e.g. 2, 3, 4, 5, 6) which are potentially useful for evaluating (simulating) on paper such alternatives as possibles process operating or configuration changes, the effects of ore and reagent changes, etc. It appears to be commonly accepted that a complete scientific/engineering characterization of flotation is immensely complicated and not sufficiently developed at the present to accurately predict (or understand) many important industrial facets of flotation. Thus, one is often reduced to detailed experimental characterization in both the laboratory and plant in order to fully evaluate flotation changes or alternatives. It is the purpose of this paper to describe a method of batch laboratory data characterization that is useful in evaluating flotation chemical reagents including froth flotation of coal. The approach consists of running a series of time-recovery curves in a batch float cell followed by the computer curve fitting of this data to a series of mathematical models based on semi-physical reasoning. The unknowns or parameters of these models are then optimally chosen so as to best fit the experimental data. It has been found in both coal and mineral systems that changes in reagent type, concentration, system pH, grind, etc. cause very consistent and logical changes to

Jan 1, 1979

By Don Runge, John T. Zeni

Cuprex Limited is currently developing a small gold mining operation in Central Australia in the Tennant Creek field. In February 1984, the company undertook a feasibility study on the project and operations commenced in August 1984. Ore reserves are located between 230 and 280 metres (755 ft and 919 ft) below surface and ore extraction required the establishment of a shaft network for access, ore hoisting and ventilation. Zeni Drilling Company from West Virginia, U.S.A. was contracted to blind drill two shafts for the project. Blind drilling was selected for various reasons, including timing which related to cost efficiency. The blind drill shaft technique has proved successful in this application and with enthusiastic and innovative support from the mining industry, will prove an efficient and cost effective means of accessing and operating underground mining projects of all sizes in the future.

Jan 1, 1987

By G. A. Kordosky

There are a number of reasons why the solvent extraction of molybdenum deserves attention: 1. The solvent extraction chemistry of molybdenum is interesting and complex, 2. The price of molybdenum is predicted to average about US$ 20.00 / pound in 2010 and, as China, India and other countries develop, the demand for specialty steels will increase putting long term demands on molybdenum supply, 3. Uranium ores often contain significant concentrations of molybdenum[1] and typically yellow cake will have a moly specification which when exceeded brings penalties, and 4. The valuable metal rhenium is a byproduct of molybdenum recovery circuits.

Jan 1, 2010

By AMIR EHSAN KIANFAR, Moritz Ziegler, TOBIAS HARTMANN, ELISABETH CLAUSEN

Accurate positioning information is a central step in the process of increasing automation and digitalization in the mining industry. Underground mine environments are prime examples for GNSS-denied environments that pose several additional challenges for the employed indoor positioning system (IPS). This work presents an ultra-wideband (UWB)- based system specifically tailored for underground mine environments. Initially, the UWB technology is reviewed and basic concepts of IPS are explained. Both software and hardware are described in detail, including positioning algorithms, electrical circuitry and the mining-compatible enclosure. Finally, the results from field tests in an underground mine are presented and positioning performance and the influence of dilution of precision (DOP) on positioning results are empirically evaluated. The results show that the localization errors are mostly below 1 m. Individual zones of high localization errors are suspected to be caused by noise interference. Significant DOP influence due to the mining drift geometry can be confirmed. The system shows promising localization results for different mining applications, while influences negatively impacting the accuracy are presented as items for future research.

Jan 1, 2024

By Brian Hester

Many Third World African countries are well-endowed with minerals - especially gold and diamonds - while only a few have important base metal deposits. For decades since colonial rule, political and economic conditions discouraged interest by Western capital. Influence from Soviet Bloc countries, however, has declined with the move toward multi-party rule. And the left wing orientation, once widely favored by Third World African countries, has almost disappeared. With International Monetary Fund (IMF) encouragement, these Third World African countries now encourage representational government and solicit western finance to expand their industries. Mining is especially encouraged. The North American mining industry is following the same trail as other capital intensive industries and looking abroad for opportunities. The Prospectors and Developers Association of Canada released figures that show exploration expenditures in that country were halved between 1987 and 1990. Figures for the United States are not so easily found but every indication points to a downward trend. While total annual expenditures on US exploration by corporations as a group are either declining or remaining constant, expenditures away from North America is increasing. Gold exploration expenditures in 1991 by the major companies tracked by Minerals Economics Group were less in the United States than for Latin America and the Southwest Pacific combined. The same study showed as much was spent in the Republic of South Africa and "Other" areas combined as in the United States. Expenditures by major corporations in these "Other" areas amount to only 5.2% of their total budget. Third World Africa is a major component of these "Other" areas.

Jan 1, 1993

By Mirza Muhammad Zaid, Nana A. Amoah, Ping Chang, Guang Xu, Ashish R. Kumar

The key takeaway of this study is the significant improvement in dust protection for roof bolter operators in underground coal mines. The optimized canopy air curtain (CAC), with a redesigned two-level manifold system, provides uniform airflow distribution that effectively reduces dust exposure. By enhancing the protection of operators from harmful respirable coal and silica dust, this technology can reduce the risk of diseases such as coal workers’ pneumoconiosis (CWP) and silicosis. The application of this optimized CAC design in real-life coal mining operations can dramatically improve worker health and safety by minimizing dust-related exposure, ensuring compliance with industry regulations and prolonging the lifespan of mining equipment by reducing dust accumulation.

Dec 1, 2024

By M. Moats, I. E. Paschalidou, K. Awuah-Offei

Tellurium (Te) is a rare metalloid that is predominantly produced from the treatment of anode slimes formed during copper (Cu) electrolytic refining. The US Government lists Te as one of the 50 critical minerals, partly, because of its use in thin-film photovoltaic (PV) technology. Given policy initiatives to increase Te production, it is important to evaluate the life-cycle environmental impacts of Te recovery as a by-product of Cu processing. The literature contains a few specific life cycle assessment (LCA) studies of groups of metals that include Te without proper regard to impacts per life-cycle stage of Te production or the effect of allocation on the results. This study builds an LCA model of the production system of Te from anode slimes treatment to evaluate the effect of allocation on life-cycle impacts. We build life cycle inventories using data from the Ecoinvent v3.7.1 database, literature, and engineering calculations and allocate impacts in proportion to products’ mass and economic value. The results show that economic value-based allocation yields greater impacts than mass-based allocation indicating the significant effect of the allocation approach on life-cycle impact estimates.

Feb 1, 2023

By R. L. Grayson, R. C. Althouse, L. A. Layne, M. J. Klishis

Introduction The researchers combine a detailed microanalysis of accident data and roof bolting field observations to develop new and meaningful risk indices for the roof bolter job classification. These indices incorporate information that has not been used in traditional measures of risk. The significant parameters that these new indices incorporate are the total number of accidents occurring within a particular work activity, the amount of time a miner usually spends performing the work activities in which the accidents occurred, and the average severity of the injuries incurred in the accidents. Being specific for a particular job, they aid comparisons among work tasks performed in the bolting cycle. The indices' specificity provide anew basis for reexamination of training and operational development of miners for specific jobs. Microanalysis The roof bolting microanalysis was performed by examining the empirical data and written summaries for all bolting accidents reported in the West Virginia Safety Information System (WVSIS) for the years 1983-1987. The WVSIS database contained more than 15,000 accident narratives. The microanalysis of bolting accidents covered 2083 reported personal injuries (RPIs). This large number of injuries, performed at an industry-wide level, provides a broad picture of the nature of roof bolting injuries. The analysis focuses on the activities associated with the cyclical routines of the roof bolting process. For this analysis, roof bolting tasks were categorized into work routines based on the sequence of work activities performed by roof bolters. Four work routines were identified within the overall bolting cycle. And these routines comprised 70% (1217) of all roof bolting accidents at the face. The routines include: face area preparation; tramming, positioning and setting the automated temporary roof support (ATRS); drilling holes; and installing bolts. The types of injuries most common within a routine and the average severity of those RPIs were also identified. Table 1 gives a breakdown of the percentage of accidents by the bolting routines. Another 19% of the roof bolting RPIs cannot be classified in a particular routine because of the vagueness of the narratives. However, it was clear that these accidents involved drilling holes or installing bolts. These results are consistent with previous research. It identified drilling and bolting, followed by tramming, as the most frequent sources of injuries (Helander, Krohn & Curtain, 1983). [Table 1-Accidents by bolting routines at the face Accidents Bolting routine Percent Number Face area preparation 18.2 222 Tram, position, ATRS 23.3 284 Drilling holes 34.2 416 Installing bolts 24.2 295 Total 1217] Roof bolter operators were involved in 82% (1706) of the 2083 accidents. The RPIs incurred by classified roof bolters occurred largely on working sections (95%) and at the face area on the working section (75%). Approximately 23% of the 1706 roof bolter RPIs occurred during tasks which were not part of the bolting cycle. These included belt utility work, providing supplies and section moves. Miners in other job classifications who were involved in roof bolting accidents accounted for the remaining 18% of the 2083 roof bolting RPIs. Among this group were section utility men and general laborers (41%), section machine operators (38%), and electricians and mechanics (11%). Another 9% were performing on-section supervisory functions. Face area preparation Face area preparation work led to a substantial number of injuries, although it accounted for the lowest number of injuries of the four routines. Several tasks were associated with the injuries incurred in this routine. Table 2 shows the percentage of injuries associated with face area preparation. [Table 2- Accidents occurring during face area preparation 26.6% Setting temporary and supplemental supports 24.8% Scaling roof and ribs 21.2% Installing ventilation devices 15.8% Handling supplies and materials 11.6% Miscellaneous tasks] The injuries commonly involved overexertion and 'struck by' falling coal and rock. Handling materials often led to overexertion injuries. Nearly 66% of the scaling-related injuries and about 33% of the injuries incurred during the setting of temporary supports involved 'strikes' by equipment, materials, top and rib. Tramming, positioning and setting the ATRS During tramming operations, workers were often struck by components of the machine and hit by loose roof and rib. Poor footing also led to slips, sometimes against the moving machinery. Table 3 gives a breakdown of accidents in this routine. Control levers were a significant problem in this routine.

Jan 1, 1993

By S. G. Britton

"INTRODUCTION Strategies to improve performance in mining production, maintenance and mineral processing operations has evolved over time from straightforward time studies of individual machine performance in the 1960’s-1970’s to more sophisticated and better focused statistical and financial tools that have emerged in the 1980’s-1990’s . These newer strategies fall under the broad descriptive category of “Operational Excellence”. Operational Excellence is the term that embodies a number of performance evaluating strategies, the most popular and relevant to mining includes the following: • Six sigma for addressing errors within mining or milling process and work standards • Lean manufacturing to optimize organizational and operational performance through continuous improvement. There are other strategies that can be applied as well and this paper is not focused on a review of the pros and cons of any one strategy. However, the common threads in these strategies embody the expectation that expected results from these efforts can be quantified and that value will positively benefit the targeted work process, organizational unit, equipment deployment or time schedule when applied to it as part of continuous improvement efforts. The priority for proceeding with any one or more of these efforts is based on the calculated net value of the required resources to affect the change versus the estimated value gained. The practice is identified as the value mapping process. This discussion summarizes the value mapping process methodology used at a mature uranium mine and mill in northern Canada to work through the myriad of potential improvement efforts available through the operational excellence process for continuous improvement.THE RABBIT LAKE MINE AND MILL The Rabbit Lake Mine and Mill are located in northern Saskatchewan, Canada on the shores of Wollaston Lake (Figure 1).The mine was discovered in the mid-1960s and was built by Gulf Minerals, Ltd. The mill began processing uranium ore into yellowcake in 1975 from an adjacent open pit mine. A whole ore acid leaching followed by solvent extraction and precipitation forms the basic milling processes. The operation continued to produce yellowcake through a succession of open pits and finally opened an underground mine in the early 1990s. Since beginning production, over 200 million pounds of yellowcake has been packaged from the site, making it the sixth highest producing uranium mine of all time."

Jan 1, 2016

By A. W. Khair

This paper presents an analysis of surface subsidence characteristics in room and pillar mining using physical models and laser holographic interferometry (holometry). The analysis included the effect of various geometric parameters and different overburden materials (sand and gelatin) and resulted in the formulation of a more realistic model material for laboratory simulation of typical geologic overburden. Previous work using this technique involved the use of sand to model over- burden and detailed results are presented elsewhere (1). The main emphasis of this work was to develop a gelatin based mixture which would provide a better model. Initial work during the development of this model included testing various ingredients and monitoring the time dependent characteristics of the model, such as the surface penetration resistance. This value indicated changing deformability/ridgidity of the model with time. Once several models had been developed, holometry techniques were applied. Initial tests showed that the stiffness of gelatin created a bridging effect over the mine models, thus restricting deformation. At this point, a 0.5 inch (1.27 cm.) layer of sand was placed directly over the mine model with the gelatin mixture on top. The approach was to model different zones of overburden movement that exist as an extraction occurs (2). The sand would represent the caved and fractured zones which occur above the excavated area. The gelatin models the continuously deformed zone which occurs between the fractured zone and the surface. Holometry techniques applied to this model yielded successful results.

Jan 1, 1986

By William E. Bruce

Percussive drill calibration experiments performed by the Bureau of Mines on two drills are described. The use of a linear velocity transducer to determine piston velocity, blow frequency, and piston stroke length is discussed. Data are presented on the relationships between maximum work rate and feed air pressure. Penetration rates in nine rock types were measured for the same two drills. Physical properties of the nine rock types are presented in tabular and graphical form to show relationships between penetration rates and physical properties. Finally, conclusions are drawn as to the potential use of these data to predict percussive drilling rates.

Jan 1, 1970