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By F. Ferella

In this paper several leaching tests were per-formed to optimize the leaching section of a hydrometallurgical process for the recycling of alkaline and zinc-carbon batteries. Zinc and manganese oxides were dissolved by an acidic-reductive leaching using sulphuric acid and oxalic acid as reductant. Leaching tests were developed according to a full factorial design. The operational variables were pulp percentage, sulphuric acid concentration, temperature and oxalic acid concentration. Additional tests were performed to evaluate the precipitation rate of Mn and Zn oxalates. Finally a hydrometallurgical process were proposed for the recycling of alkaline and zinc-carbon batteries, in which Zn and MnO2 are recovered from purified solution by electrowinning: Zn is recovered as metallic compound, while Mn can be recovered as electrolytic manganese dioxide (EMD), but recovery of further manganese compounds is possible with simple process changes.

Jan 1, 2006

By Lauro Lacerda

Shotcrete is a highly adaptable and widely used underground construction material at infrastructure and mining projects around the world. In fact, many projects could not have been completed without its utilization. As underground projects became larger the use of mechanized wet-mix spraying gradually replaced manual dry-mix shotcrete applications. This paper details some of the reasons for that and provides information on the equipment and operational factors including safety and productivity required to successfully complete underground shotcrete projects.

Jun 13, 2021

By J. H. Rowland, A. C. Smith, K. A. Teacoach

Current regulations for fire suppression systems in underground coal mines to protect conveyor belt installations have been in place since the Coal Mine Health and Safety Act of 1969 was enacted. Over time, the coal conveyer equipment being used and ventilation conditions underground have changed significantly, particularly the width of the conveyor belts and the use of belt air at the face. The effect of these new conditions on the effectiveness of suppression systems during a fire is not known. The National Institute of Occupational Safety and Health (NIOSH) conducted a study to evaluate the effect of air velocity, water sprinkler activation temperature and a limited water application time on the effectiveness of water sprinkler fire suppression systems to extinguish large-scale conveyor belt fires. The fire tests were conducted using both new and used 1.8-m-wide, fire-resistant rubber belt that met the Mine Safety and Health Administration (MSHA) flame-resistant requirement specified in Title 30, Code of Federal Regulations, part 18, section 18.65 (also known as the 2G test). Tests were conducted using standard response sprinklers with activation temperatures of 68° C and 141° C at air velocities of 0.5 and 5.1 m/s. Two tests were conducted at both air velocities for each sprinkler activation temperature, one using a new belt and one with a used belt. The results showed that the suppression system was able to suppress the fires in ten minutes to the point that a miner could extinguish it with a fire hose. However, in several of the tests, the fire reestablished itself a few minutes after the sprinkler water supply was cut off and quickly grew out of control. This report discusses the large-scale experimental configuration, the installation specifications of the fire suppression system and the results and conclusions regarding the effect of air velocity, sprinkler activation temperature and limited water application on the suppression system performance.

Jan 1, 2010

By Palmer C. Sweet

Kyanite. andalusite, and sillimanite are anhydrous aluminum silicate minerals, and they have the same chemical formula, Al2SiO3. Dumortierite and topaz are also classified as aluminum silicates although they contain boron and fluorine respectively. Mullite (a rare mineral named for its discovery site, the Scottish island of Mull) is produced when kyanite, andalusite, or sillimanite are heated. Synthetic mullite, also classified as an aluminum silicate, is formed by melting alumina and silica, bauxite, and kaolin or alumina, kaolin, and kyanite, depending on the type of synthetic mullite desired. These materials are either sintered in rotary, periodic, or tunnel kilns, or fused in an electric arc furnace. The world's largest producer of kyanite is the United States. Domestic kyanite is presently produced from one company at two sites in Virginia; Kyanite Mining Corporation mines kyanite from Willis Mountain and adjacent East Ridge in Buckingham County in the central Piedmont province of Virginia. Internationally, kymite is produced in Australia, Brazil, India, Kenya, Sweden, and Zimbabwe; the former USSR also produces kyanite (Fig. 1). Andalusite is produced by Piedmont Minerals Company, Inc. in the Piedmont province near Hillsborough, NC. Andalusite is also produced in France, India, the Republic of South Africa, and Spain (Fig. 1). Sillimanite is produced in Australia, Brazil, India, Spain, and the Republic of South Africa; the former USSR is also thought to be a major producer (Fig. 1). Some of the countries produce only for domestic use. Synthetic mullite, made by sintering and by electric arc fusion, is produced by Mulcoa (Mullite Company of America) in Andersonville, GA, and by Washington Mills Electro Minerals Corporation in Niagara Falls, NY. Annual world production of kyanite, andalusite, sillimanite, and synthetic mullite is approximately 672 727 tons (Potter, 1988). GEOLOGY Mineralogy Kyanite is a blue to light-green, triclinic mineral that occurs in long, thin-bladed crystals and crystalline aggregates in gneiss, schist, and pegmatites. The mineral has a hardness of 5 parallel to the long axis of the crystal and a hardness of 7 across the crystal. Andalusite is a yellow, brown, green, or red orthorhombic mineral that occurs in thick, almost square prisms in schist, gneiss, and hornfels. Gem quality andalusite exhibits a strong pleochroism; brownish-green in one direction and brownish-red perpendicular to it. Andalusite also occurs in placer concentrations where it has weathered out of rock. Sillimanite is a brown, pale-green, gray, or white orthorhombic mineral that occurs in long, slender, needlelike crystals in schist and gneiss. Chemical and Physical Properties Chemical and physical properties of kyanite, andalusite, and sillimanite are noted in Table 1. Kyanite is the only mineral that irreversibly expands when heated (calcined to produce mullite) and may offset the shrinkage of most ceramic or refractory ingredients when heated.

Jan 1, 1994

By James R. Arnold

Gold Fields Mining Corporation started processing ore from it's Chimney Creek operation in northern Nevada in November, 1987. Since that time production has averaged about 200,000 ounces per year from the milling and dump leaching circuits combined. The events that led up to commissioning of the plant started in January of 1985 when the Gold Fields exploration team drilled their first hole in an area now known as Discovery Hill. The major orebody was located later in the year in what is currently the major focus of activity, the North Pit. Subsequent drilling since plant startup has found another 14 million tons of ore two miles south of the original orebody. This South Pit orebody is currently being stripped and metallurgical testing is underway. Engineering Engineering on the Chimney Creek plant started in earnest in May, 1986. Davy McKee Corporation from San Ramon, California, did both the engineering and the construction management. Before engineering began the entire senior staff of the Plant Department was hired and assigned to the project. Senior staff included the Plant Superintendent, Plant General Foreman, Maintenance General Foreman and Chief Metallurgist. Gold Fields does not employ an internal central engineering staff to design their plants. We feel that the people who design the plant should be the ones who will be required to run it once it has been commissioned. This philosophy affords a continuous accountability from start of design through commissioning and operations. All four of the senior staff spent the most critical phase of the engineering stage at Davy McKee, so the plant is truly a reflection of all four disciplines. In bringing on the Maintenance General Foreman from the start, there was a focus placed on ease of maintaining the plant. Another philosophy that was adopted from the start was that the plant be easy to work in and maintain for both operators and maintenance personnel. Numerous design criteria were given to Davy McKee to ensure this. For example, we required that every piece of equipment could be reached easily with a crane or fork lift. All conveyors were required to have walkways on both sides for ease of maintenance and a minimum of 30 inches of clearance under them for ease of cleanup. Visibility for operators was considered very important and the control rooms and general plant layout were designed with this in mind. A list of about 100 general rules were given to Davy McKee during the early layout meetings and these were held as the general design criteria throughout engineering and construction. While engineering was progressing in San Ramon, California, dump leach test work was being done at the site. Three 6 foot diameter fiberglass columns were constructed and filled to a 20 foot height with low grade ore. Leaching characteristics were determined and the dump leach design was based on information collected from these columns. Construction The major contractors on the project were The Industrial Company for the bulk of the piping and structural, EMKO on the electrical/ instrumentation and Hunewill for most of the earth work and leach pad construction. All plant operating and maintenance personnel were employed eight weeks before startup for intensive training. Instructors were Gold Fields personnel, including foremen, and Davy McKee engineers. On occasion, selected suppliers representatives were brought in to discuss major pieces of equipment. Project completion was targeted for January, 1988 at a projected cost of 78.9 million dollars. Actual startup was about 1 1/2 months ahead of schedule and slightly under budget. Full design capacity was achieved the first full month of operation. Crushing Run of mine ore is delivered to the crusher and dumped into a 90 ton hopper which is topped with a 30" X 30" opening stationary grizzly. Ore is fed to a 50" X 60" Telsmith jaw crusher with a 5' wide apron feeder. The closed size setting of the

Jan 1, 1989

Conveyor belting-Dunlop Belting Division has published a manual on its Starflex plied conveyor belting. The design section of the manual contains advice on the calculation of tensile strength and horsepower needs while the section on belt selection offers helpful recommendations. Circle 200 on reader service card Hydrostroke feeders-A pamphlet from Kone Corp. highlights the uses and operating principles of its hydrostroke feeders. Circle 201 on reader service card Electric cylinders-A 24-page catalog from Raco International Inc. describes applications for its electric linear actuators in addition to the electronic options for computer - controlled operation. Circle 202 on reader service card High torque drives-T. B. Wood's Sons Co. offers a 56-page booklet providing features and specifications on its high torque drives. Information includes a step-by-step drive selection proce¬dure. (HTD) Circle 203 on reader service card Sludge depth meter-The model 600 sludge-depth meter that locates the sludge bed in clarifiers and settling tanks is described in a four-page bro¬chure from Markland Specialty Engineering Ltd. (600-84) Circle 204 on reader service card Cavity pumps-An eight-page bulletin is available from Robbins & Myers Inc. It features the application of Moyno progressing cavity pumps in handling composite slurry fuels. (400) Circle 205 on reader service card Roller chain-A roller chain catalog shows heavy duty drive chains and other specialty conveyor chains. It is available from Peer Chain Co. (PC200) Circle 206 on reader service card Belt filter-Phoenix Process Equipment Co. has available a pamphlet detailing its belt filter press. The unit is designed to dewater refuse and clean coal, yielding easily handled dry filter cakes. Circle 207 on reader service card Capabilities - Literature from International Mineral Services Ltd. highlights its services and capabilities to the mining industry. Circle 208 on reader service card Motor analysis - How to select the proper electric motor by comparing life cycle costs, power costs, rate of return, and other factors, is described in a brochure from Westinghouse Electric Corp. (SA-11376) Circle 209 on reader service card Cavity pumps - A product application data sheet is available from Robbins & Myers Inc. It details the use of Moyno positive-displacement, progressing cavity pumps in handling ground limestone slurry. (PC-21) Circle 210 on reader service card Dust collectors - "Dust Collector Selection Guide," from American Air Filter, describes dry mechanical collectors, wet collectors, fabric collectors, and electrostatic precipitators. (CAD-1-901G) Circle 211 on reader service card Wet scrubber - A 12-page bulletin from The Ceilcote Co. provides a comprehensive description of its ionizing, wet-scrubber system. (12-19) Circle 212 on reader service card Metric o-rings-Simrit Corp. has published a 16-page brochure detailing its full line of standard metric o-rings. Information includes graphics and dimensional charts, and specific data on materials and application ranges. Circle 213 on reader service card Hearing protection - A 16-page catalog from Cabot Corp., EAR Division, provides information on its hearing protection devices and noise control products. Circle 214 on reader service card Toxic gas detection - Sensidyne Inc. is offering a guide for toxic gas monitoring. A description of the electrochemical sensors, as well as ranges, complete specifications, and interference charts are included. Circle 215 on reader service card Hydraulic bolting systems - Ingersoll-Rand Co. is offering a brochure on its line of hydraulic bolting systems. These systems, hydraulic wrench and power console, are designed for heavy duty bolting applications. Circle 216 on reader service card Temperature monitoring - A brochure describing the Ramsey Engineering Co.'s micromonitor temperature monitoring system is available. Three types of switches are available for monitoring bearing temperatures. (80.300) Circle 217 on reader service card Product catalog - Shadbolt & Boyd Co. has published a product catalog. Among items described are hoist slings and cranes; compressors; hydraulics; wire rope, chains, and fittings; and materials handling and shop equipment. Circle 218 on reader service card Cylinder controls - A 12-page booklet presenting Hanna Corp.'s line of electrical controls for cylinders is available. It features proximity and limit switches for hydraulic and pneumatic cylinders, and standard and 3-amp reed switches for pneumatic cylinders only. (550) Circle 219 on reader service card Slurry pump - Pettibone Corp. has published a 24-page booklet covering its heavy duty pumps made with 'diamond alloy' materials for handling slurries of abrasive materials. Circle 220 on reader service card

Jan 9, 1985

By A. E. Raddatz

The U.S. Department of the Interior, Bureau of Mines, is investigating methods for recovering tungsten from domestic resources. A calcine-quench-leach (CQL) technique was developed for the extraction of tungsten from the Golconda, Nevada, hot springs ores. The deposit contains disseminated tungsten, which cannot be beneficiated by conventional techniques and must be treated by hydrometallurgical methods. The CQL procedure consists of calcining the ore at 900° C for 3 hr, quenching in a solution containing 1.5 parts of NazCO3 and 1.5 parts of NaOH per part of WO3 in the ore and at a solution- to-ore ratio of 3 to 1, leaching at 200° C and at 250 psig for 3 hr, and filtering and washing the residue. A series of closed-circuit batch tests showed that 92 pct of the tungsten was extracted from a sample containing 2.32 pct WO3. The pregnant solution contained 11 q of W03/1.

Jan 1, 1982

By J. Paraszczak

Metal mining at great depths presents a number of serious challenges for mine operators. Among them is the high demand for fresh air required to cool down mine openings, evacuate noxious gases and contaminants and provide sufficient amounts of oxygen for miners. At the same time, modern mechanized mines extensively use diesel-powered load-haul-dump (LHD) machines, trucks and other mobile equipment. These vehicles not only emit exhaust gases and diesel particulate matter (DPM), but constitute an additional source of heat. As mine regulations get steadily more stringent with regard to air quality, the use of diesel engines has an additional adverse impact on ventilation costs. In this context, the present paper examines possible alternatives for diesel power trains, both those commercially available and those in development. They are reviewed with regard to their principles, required infrastructure, stage of technology development and progress. The questions of their flexibility, practicality and economic viability are also addressed. Finally, their possible benefits and potential for implementation in the conditions of deep metal mines are discussed. The paper concludes with short- to medium-term predictions concerning promising drive alternatives for vehicles destined to operate in deep metal mines.

Jan 1, 2009

By Erich J. Jacob, Volker O. Meldner

INTRODUCTION Our company has made persistent efforts to utilize the very latest cost-saving technology in tunnel design and construction. However, we were relatively late in joining the clan of slurry shield tunnelers. The challenge came in 1973, when our company was low bidder on a major sewer tunnel in Hamburg, West Germany. The tunnel was to be driven under the harbor region through coarse and fine sands with up to 60 ft hydrostatic head of water. Outer diameter was 15 ft, and length was 2.9 miles. This contract appeared right to enter the new field of slurry face tunneling. We gathered a design-engineering team to develop the machine, called it "Hydroshield", and used it on the project. The good performance of the prototype machine encouraged us to improve and modify the equipment design. The very latest model is now in use on a subway tunnel in Antwerp, Belgium. This tunnel is 21 ft outer diameter and 2.4 miles in total length. In terms of excavated volume it is the world's largest slurry shield contract. While the drive is still in full swing, we are currently preparing for 3 further Hydroshield applications, with diameters ranging from 12 to 32 ft. This paper describes the Hydroshield's salient design features, operational characteristics, construction reliability and performance levels, as experienced in West Germany and Belgium.

Jan 1, 1979

By Jed Greenwood, Lyall Workman, Michael Haggerty, Russell Sheets

Draglines often work from a position on the active highwall or spoil side bench to remove undisturbed waste material and spoil in the previously mined pit. To protect the dragline crew members and the machine, it is necessary that the highwall remain stable while the dragline is present on the bench. In the past several years, we have been involved in determining the causes for highwall failures that included the dragline. While there have been no injuries and limited dragline damage with these incidents, the potential certainly exists for a more serious outcome. In all cases, the operation had completed a geotechnical study to support the ground control plan and pit designs. However, all these incidents included aspects that would not likely have been identified in studies to determine highwall and spoil designs to support ground control procedures. In general, these events included aspects that were localized and would have been difficult to identify in initial slope stability studies either observationally or during the soil testing and modelling efforts. Although the authors do not have quantitative evidence of this, it does seem there has been an increased number of events in recent years. This may be due to loss of institutional knowledge, mining in more challenging areas, or simply an increase in localized variation. This paper will describe some of the issues we have seen and what the causes of failure were. It becomes clear that avoiding similar incidents in the future requires on-going observation and inspection of active highwalls and spoil benches to try and identify local variability and impact on mining. The information can proactively be used to update stability modeling of any concerning issues to determine likelihood of problems and to develop solutions.

Feb 1, 2025

By Anand Kumar, Debasis Deb, A. K. Mishra, M V. N. S. PRASAD.

In the Adriyala project, shield-leg pressure data from all shields and shearer location with time stamp from a mechanized longwall face are monitored and recorded in a surface computer. The data contain random noise due to power failure, leakage of legs, bad sensor readings, and other maintenance or geomechanical problems. An algorithm has been developed to detect mining cycle parameters such as setting and final pressures and duration of the cycle from these data for the analysis of periodic roof weighting phenomena. The intensities and persistence of periodic roof weighting are vital information for mine management to make judicious decisions on longwall operation.

Direct force measurements were conducted using an atomic force microscope (AFM) to study the mechanism of copper-activation of sphalerite. The force measurements were conducted between a sphalerite plate and a hydrophobic glass sphere in xanthate solutions of various pHs. The glass sphere may represent the hydrophobic air bubbles interacting with minerals during flotation. The force measurements conducted with unactivated sphalerite in 10') M KEX solutions did not show the presence of hydrophobic force. On the other hand, the results obtained with copper-activated sphalerite at pH 9.2 and 4.6 showed strong hydrophobic forces. However, the results obtained at pH 6.8 showed no evidence of hydrophobic force, which provides an explanation for the difficulty in floating sphalerite at neutral pH.

Jan 1, 1998

By S. Amirshenava, S. Nadimi

"Premature and unplanned mine closure can result in significant adverse impacts on the environment and community and need to be managed appropriately. Risk management techniques can reduce the negative impacts and risks of early mine closure. Risk Assessment 3D Model, is an efficient tool to quantify risk. The aim of this paper is to identify the mine closure risks in Choghart iron ore mine, and calculate the overall mine closure risk level. The result shows that 51.4% of assessed risks have low risk level and the overall risk level of early mine closure is low. Keywords: mine closure, risk assessment 3D model, Choghart iron ore mine INTRODUCTION The modern mining life-cycle can be divided into three main stages; exploration, mining (opening and production) and post mining (mine closure, and reclamation). Mine closure is the critical component of the modern mining life-cycle and it refers to the period of time when the operational stage of a mine has permanently ceases (Heikkinen et al, 2008). Planned closure occurs due to the depletion of ore reserves, but sometimes it is premature. Laurance (2006) shows that only 25% of mine closure in the past 30 years was due to resource depletion and in 75% of the cases the mines were closed for the other reasons. Ghanbari et al (2010) demonstrated that 48.6 % of copper mine closure in the past 100 years was due to resource depletion and 51.4 % of copper mines have been closed due to other reasons. The main reasons of premature mine closure are as follow (Laurance, 2006; Ghanbari et al, 2010; Maiti, 2013): • Economic, (low commodity prices or high costs) • Geological, (over-estimation of grade and tonnage) • Geotechnical (adverse geotechnical conditions) • Technical (equipment failure) • Regulatory, due to safety or environmental breaches • Social or community pressures • Closure of downstream industry or markets • Flooding or inrush Minaei Mobtaker and Osanloo (2013) developed a mine closure prediction model based on the data collected from closed iron ore mines in the past 100 years. They showed that economic factors, exhaustion of ore reserve and geological conditions are the main reasons of iron ore mine closure. They treated mine closure as a decision making problem in order to predict the causes of mine closure, including the uncertainties of some mine plan parameter such as iron ore price, production and consumption."

Jan 1, 2016

By Dennis Molvik, Omar Fulton, Chris D. Breeds, Don Gonzales

The Tolt Pipeline No. 2, West Snoqualmie Valley project, is part of a water supply project linking the Tolt reservoir in East King County to the City of Seattle through a nominal 2.13 m (7-ft) inside diameter conveyance. Receipt of the National, 2002Microtunnel Award provided recognition of the many challenges overcome by this project. Baseline conditions revealed in the Geotechnical Documentation included over-consolidated glacial deposits, landslide and alluvial deposits, artesian water, boulders up to 36-in in diameter, logs, heaving sands, and liquefiable soils beneath the river. Schedule constraints associated with setting the shafts in the floodplain of a salmon bearing river and the fickle performance of the river during those times it was not supposed to flood added to the challenge.

Jan 1, 2003

By S. K. Kawatra

Three International Symposiums-the 14th International Minerals Processing Congress, the 17th APCOM, and the SME-AIME Fall Meeting special symposium on Design and Installation of Com¬minution Circuits-held in 1982 contained a number of papers relating to the fundamentals of processing coals and metallic minerals. In addition, many papers were published elsewhere in the literature. Some of the more significant papers are discussed below. Flavel reviewed key performance parameters, such as energy-size relationships for crushing processes and presented a fundamental basis for optimizing crusher productivity and possibly for development of improved crushers. Pascoe et al. reviewed the use of such control schemes. Magerowski and Karra presented a paper on a computer program developed to and in the design of crushing circuits. The problems associated with the scale-up to very large ball mills were discussed by Arbiter and Harris, and by Kavetsky and Whiten. Both groups concluded that limits on mill productivity arise due to problems associated with particle breakage and transport through mills. Austin et al., and Herbst and Rajamini reviewed the state of the art for the use of grinding circuit simulators for design and control. The effects of mill operating and design parameters on selection and breakage were discussed in detail. The philosophy of control and instrumentation for grinding circuits was extensively discussed by Kawatra and Seitz. Their paper presented for the first time an analytical basis for the inferential particle sizing technique and provided a fundamental basis for the implementation of this technique. The effect of reagent addition variation's on the performance of coal flotation circuits was reported by Kawatra and Waters, and on sulfide flotation circuits by Klimpel et al. Both groups analyzed circuit behavior from a kinetic point of view and reached similar conclusions on the effects of collectors and frothers. The computer simulation of an iron ore flotation circuit also was reported by Kawatra et al. In this work particular attention was paid to the phenomena of froth overloading. Klimpel et al., Kawatra and Waters, and Niemi et al. discussed the philosophy of control by flotation circuits from a fundamental kinetic point of view. An extension of the use of high intensity magnetic separators to the beneficiation of specular hematite was discussed by Thayer and Linkson.

Jan 5, 1983

By Rajendra K. Devala, Sukumar Bandopadhyay

In order to be able to design an adequate mine ventilation system it is necessary to understand how pollutant masses disperse into turbulent ventilation air streams. The mixing of gases and dusts with ventilating air, and dispersion of these pollutants in mine airways, are important flow or transfer problems. For the solution of such problems, the finite difference technique is often used. In this paper, numerical approximation schemes for the solution of the mass transfer problem have been developed using several explicit finite difference schemes. Results from these schemes have been compared with the analytical solution for spatial and time increments using the concept of Root Mean Square error. The comparison of various schemes reveals that the explicit finite difference schemes analyzed here give more accurate results at lower velocities, though the results are dependent on the spatial and time steps considered. At higher velocities the schemes tends to oscillate about the analytical solution. INTRODUCTION In mining, most of the mine air pollutants, such as respirable dust, methane, blasting fumes and diesel exhaust, are produced at the mine face and in haulageways. Injection of any of these pollutants in the mine ventilating air causes disturbances of the equilibrium state of the pollutant concentration of the ventilating air. The mixing of these gases and dusts with the ventilating air are typical examples of mass transfer processes. Pollutants are diluted by the stream of ventilating air flow along airways and discharged into the outside atmosphere of the mine through a return shaft. The dispersions of these pollutants in mine airways are important flow or transfer problems. Knowledge about pollutant sources, emission and transport of these pollutants are essential for ventilation planning and design to ensure good engineering control over air quality, quantity, and environmental conditions. Modeling of mass transfer phenomena in mine ventilation is largely based on extensive studies of turbulent dispersion in wind tunnels and the lower atmosphere of the earth. The general approach in the formulation of models lies in the recognition that these mass transfer phenomena can be conceptualized as a flow problem that can be solved by the general application of Taylor's theory (1954) of turbulent flow and diffusion with modification appropriate static and dynamic parameters. If the face zone is initially contaminated by a pollutant over a long section (e.g. instantaneous exposure of large gas accumulation, rapid methane release etc.), the process of decontaminating the mine workings can be regarded as displacement and diffusion of the tailing edge of the cloud of contaminates in the form of a semi-infinite gas body, for which a one-dimensional mass transfer equation is represented by: [at + u • ax = Ex ex2 + f (x,t)(1.1)] In Eq. (1.1), the term [~~] is the rate of growth of the concentration in the differential element, while a [(5xx )] is the net gain of material due to convective transfer. The two terms balance the total loss of material due to turbulent dispersion that is represented by [Ex . 21] and f(x,t), the source term for the pollutant in the roadway. Several cases of mass transfer that occur in mining can be identified and modelled using the conservative volume element method. The governing equation, along with the associated boundary and initial conditions, source terms and their solutions are detailed elsewhere (Bandopadhyay and Ramani, 1988, Devala, 1989). Only one mass transfer situation is presented (Figure 1) here for the present analysis. Mixed Evolution of Pollutant (multiple pulses) Typical examples of these situations are emission of pollutants from multiple diesel vehicles in the face area, and gas emission from standing pillars as well as from broken coal seam during coal cutting with a continuous miner. The mathematical statement of the problem along with the initial and boundary conditions are given below, Governing Equation: [do+u- =E d2c(1.2) ataxx dx2] Initial conditions:

Jan 1, 1993

By Douglas J. Cork

Biohydrometallurgica1 processes in the areas of coal desulfurization (Hoffman, M.R., et al., 1981) and recovery of metals from metal sulfide ores (Lundgren, D.G. and Malouf E.E., 1983) are well known. In addition other areas of potential interest to the mining industries have been outlined (Spisak, J.F., 1979). For instance, scientists involved in this interdisciplinary field have endeavored to apply microorganisms to the problem of effluent sulfate disposal. This chapter assesses the feasibility of utilizing a particular two stage anaerobic microbial process to convert effluent sulfate to orthorhombic sulfur. Strong emphasis is given to the possibility of substituting this bioprocess for alternative gypsum synthesis and disposal methodologies commonly practiced by companies which emphasize sulfuric acid or ammonium sulfate leaching processes.

Jan 1, 1985

By Kurt Egger, Emily A. Baker

Rehabilitation work at the Cameron Run Tunnels entailed the restoration of seven heavily deformed, approximately 69 m long, steel liner plate supported culverts through a CSX Railroad embankment near Alexandria, Virginia. A custom fabricated expander, equipped with four 200-ton hydraulic jacks on two expansion arms was used to push back the liner plates encroaching into the proposed tunnel profile and install the steel set support. In a second phase the tunnels were then lined with 16 cm of fiber reinforced shotcrete. Geotechnical instruments both in the tunnels and on the railroad embankment were used to monitor the effects of the rehabilitation work on the two CSX Railroad tracks above the tunnels. Freight and passenger trains were required to run uninterrupted and at maximum speeds throughout construction.

Jan 1, 2003

By D. W. Park

Geologic condition is one of the most important factors for longwall mining operations, especially, the existence of faults limits the mineable area, or cause stress variations at the longwall face. Recently, a longwall panel passed through a fault at the Shoal Creek Mine of Drummond Company, Inc. The fault was situated diagonally along the longwall face and the coal seam was displaced up to 2.4 m (8.0 ft) in a mode of a normal fault. LoSCoMS (Longwall Strata Control and Maintenance System) was used for monitoring shield pressure every minute and interpreting data in terms of setting, developing and final pressures. The results of the analysis regarding the influence of the fault on the shield pressure are presented.

Jan 1, 1999

By N. R. Sainath

This paper discusses the results of a laboratory investigation carried out to study the microscale flow characteristics of copper ores and the variation in flow behavior resulting from flow of leach solution. Fractures in 1.5 and 4 inch diameter cores were mapped by visual inspection. The cores were stressed in a triaxial stress field representative of in situ conditions. The permeability of the samples to water was then estimated. The samples were exposed to 20 g/l sulfuric acid and the experiment repeated. The Permeability of unleached samples ranges from 10-1 to 10-19 m2 and it increases as leaching progresses. The porosity variation and the rate of recovery of copper from the specimen during leaching were also studied.

Jan 1, 1991