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By D. U. Gustafsson

After half a million meters drilled with Wassara we are now confident that ITH hammers powered with simple water will become an established product for production drilling. Today four drill rigs in LKAB Malmberget equipped with Wassara drill about 25 000 m per month of 4 1/2" holes. In Kidd Creek, Canada, Was sara is used for production drilling in stopes with good results. The first Wassara 6" hammer has drilled a 36 meter long, completely straight horizontal cut hole for drifting in the LKAB Malmberget Mine. Main advantages are about doubled penetration rate, very good air quality and improved hole cleaning which facilitates stabilized drilling. Disadvantages are resistance to new technology and, in some cases, the increased use of water.

Jan 1, 1995

By K. Sasaki, H. Miyakoshi, K. Mashiba

A ventilation analytical system adapting nodal pressure method using skyline modified Choleski's decomposition scheme for network-flow analysis and a new practical system to estimate various thermal air conditions has been developed. The quasi-linear equations for solving steady-state network airflow have been described using the connective function in general forms. The skyline modified decomposition scheme has an advantage on rapid convergence and the sake of computer memory space com- pared with other schemes. The key part of the analysis for climatic conditions through network airways is how to estimate the temperature of the airway rock-surface with partly or full wet condition. A practical and simple solution without any iterative calculations for its estimation has been proposed. This new solution is applicable to practical ranges of airflow temperature, humidity, rock thermal properties and wetness. The present analytical sys- tem have been successfully applied to a ventilation simulator named "M1VENA"developed by authors.

Jan 1, 1996

By D. W. Park

Underground openings resulting from coal mining activities have been a serious cause of subsidence problems in the Warrior coalfield of Alabama, which is the 11th largest coal-producing state in the United States (National Coal Association, 1986). The problem will be even more serious in the future because 17 Gt (19 billion st) of Alabama's 22 Gt (24 billion st) of coal reserves are classified as an under- ground resource (Tolson et al., 1982). Subsidence data in this area has been scarce com- pared with other coalfields (Conroy, 1980; Dunrud and Osterwald, 1980; Gentry and Able, 1978; Hunt, 1979; King and Gentry, 1979). This paper discusses the results of a study of subsidence overlying two longwall mines that contrast each other. One of them (Mine #1) is a shallow longwall mine where the coal strength is very high, and the other mine (Mine #2) is extremely deep with a low strength of coal.

Jan 1, 1987

By W. J. Martin

At the termination of mining, the quality of ground water in the ore-zone aquifer must be returned to a condition predetermined by the permitting agency. To immobilize the redox-sensitive elements (e.g., uranium, arsenic, selenium, molybdenum), it has been suggested that a reducing agent be circulated through the leached ore zone. We have conducted laboratory experiments to test the ability of sodium sulfide as such a reducing agent. Sodium sulfide lowered the redox potential of the effluent such that insoluble minerals containing the redox-sensitive elements should be stable. The uranium concentration of the solution decreased by more than three orders of magnitude. In column experiments, by the time ten pore volumes of the sulfide solution had flowed through, sulfide minerals were forming. The experimental results indicate that the addition of sodium sulfide should cause the chemical reduction of the leached sediments, thereby producing long-term stability of the ground-water/sediment system.

Jan 1, 1986

By R. Hogg, T. F. Dumm

Procedures for particle size analysis on respirable dust from coal mines have been evaluated. Using respirable dusts dispersed in a laboratory dust chamber, size distributions measured using cascade impactors have been com- pared with the results of a variety of laboratory sizing methods performed on samples collected on filters placed side-by-side with the impactors. The laboratory techniques included centrifugal sedimentation, laser diffraction/scattering and automatic particle counting. The general agreement among the various methods was very good, with systematic differences which can be attributed to the different definitions of size used. Simple conversion factors have been obtained which can be used to transform the laboratory data to equivalent aerodynamic sizes. Similar comparisons have been made on samples collected in underground coal mines. Again, the results are in quite good agreement although small discrepancies were observed in some cases. These have been attributed to some degree of agglomeration in the airborne dust, leading to slightly coarser apparent distributions in the impactor samples.

Jan 1, 1987

By G. T. Swanby

Members of AIME, I read to you now a portion of a very fine business letter which we received several years ago. This letter originated in Rangoon, Burma, and reads in part: "Rest assured, if your goodselves see with us eye to eye, sure as certain we should get the business". I don't plan to give anybody "the business" today, but you can rest assured that if some of "you goodselves see with me eye to eye" on what I am about to discuss, I would be most pleased. My talk with you today will discuss the Federal Corporate income tax and its effect on our lives as engineers. In the-engineering-construction business we are faced with all the usual form of taxation which includes such items as sales tax, use tax, school tax, contractor; gross receipt tax, import duties and excise taxes, severance taxes, etc, adinfinutum.

Jan 1, 1965

During 1997-2001, an EC funded project investigated the environmental consequences of the use of industrial waste and sewage sludge based artificial top soils (ATS) in rehabilitating large coalmine waste dumps in the Saar region of Germany. Both the laboratory leaching tests and field lysimeter data analysis carried out by the research partners have shown that the amount of dissolved heavy metals in the leachate was low, and generally below the regulatory limits. However, the dissolved amount of nutrients, especially mineral nitrogen, was found to be relatively high. The hydrological properties of waste rocks and ATS mixtures were established through history matching of the laboratory column tests and the field measurements. 1D column models and 3D field models were used to numerically simulate pollutant transport at the ATS rehabilitated waste dumps. This paper presents the findings of the numerical modelling research carried out for the characterisation of hydrological and pollutant transport properties of rehabilitated coalmine waste dumps in the Saar coalfield.

Jan 1, 2003

By Richard Jr. Ray, Richard Druesedow

The Virginia Operations of Consolidation Coal Co. include a diversity of mine fan configurations which have been tested to quantify pressure losses through the inlet ductwork. Airflow and pressure measurements were taken at four shaft sites to calculate losses for the 90-degree bend at the top of the shaft and the self-closing dampers or closing doors located between the shaft and fan. Velocity contours were then developed from the test data to determine flow patterns in each fan system component. In addition, yaw and pitch angles of airflow through the fan annulus were measured to evaluate turbulence levels created by various inlet ductwork designs. The test results indicate that proper design of the shaft collar and ductwork arrangement for main mine fans can substantially reduce system pressure losses and air turbulence. BY minimizing the pressure drop experienced on the surface, these design improvements enable the bulk of the total pressure developed by the fan(s) to be utilized in the mine.

Jan 1, 1995

The impact of smoothing on the definition of ore and waste boundaries using linear estimation and conditional simulation methods is discussed. The nature of transfer functions is examined including their ability to incorporate categorical data (e.g. a dominant lithology code). An Ore Block Optimization (OBO) transfer function is presented that provides a clear guide for the mining geologist. Advantages are seen in defining stockpile cut-off grades and meeting production targets such as maximizing head grade, maximizing ore tonnes or minimizing ore loss or dilution. Each of these scenarios impacts on mine profitability and grade control.

Jan 1, 1999

By Michael J. Martinson, John R. Larsen, J. Warren Andrews

Measurements reported in the paper were recorded in an active Green River, Wyoming, trona mine, partly as a teaching exercise and partly to provide the mine in question with additional input data for its ventilation network program. Measurements were made: - in representative three-entry intake airways in room and pillar sub-mains; - between the lower portion of a vertical down-cast hoisting shaft and the start of an intake airway system established in a room and pillar main; - in a representative downcast section of a divided vertical shaft, and of the collar entrance loss at the top of the same compartment. Pressure differences were measured with manometers and trailing hoses, air flowrates with calibrated anemometers, and barometric pressures and wet-and dry-bulb temperatures were recorded for density determinations. Where possible, results are quoted as Atkinson friction factors, and relevant measurements are recorded in some detail to show the magnitude of fluctuations in observed pressure differences.

Jan 1, 1987

By Julian Boldy

The discovery of the Delbridge massive sulfide deposit in the Noranda district of Quebec resulted from an appreciation of the significance of a mercury leakage haloas a lithochemical pathfinder to blind ore, coupled to its location relative to a geologically inferred ore-bearing horizon within complex volcanic stratigraphy. Systematic sampling of microfractures present in outcrops delineated a diagnostic anomaly, drawing attention to an area considered prospective for buried ore. The massive sulfide deposit was subsequently found to be blind and topped at the 107-m (350-ft) level. This case history is presented in the context of its time and was the first volcanogenic ore deposit to be discovered utilizing mercury as a pathfinder in the Canadian Precambrian. The case history also illustrates that the practical application of an innovative technique coupled to a new geological interpretation can result in success, even on a property that was centrally located in a mining district and had undergone intensive exploration efforts over a 38-year period.

Jan 1, 1991

By R. J. Sweigard, T. Beckman, C. T. Justice, E. D. Thompson, T. C. Hopkins

As a means of permanent disposal, fine coal refuse is often pumped as a slurry into surface impoundments. As the available volume is filled, the embankment heights are frequently increased. The additional embankment material is often placed upon consolidated fine coal refuse. There has been concern about the long-term effect of consolidation of this material at or above the liquid limit on its shear strength. A laboratory investigation was performed using three different types of fine coal slurry taken from central Appalachian coal-preparation plants. The refuse was consolidated in 3-m (10 ft) Plexiglas columns under incremental amounts of surcharge loading. The incremental loads were designed to simulate the effect of increasing the height of a refuse embankment on top of the consolidating coal slurry. After the refuse in the columns had consolidated for several months, the columns were cut apart, and triaxial tests were performed on both the consolidated and unconsolidated material for comparison of their shear-strength parameters.

Jan 1, 1998

By J. van Oldenborgh

The world market for bunkers represents some 140 MT (1980) of marine fuel oil and distillates. This is equivalent to 23CMT of coal, a potential market for steam coal larger than the total seaborne trade of steam and metallurgical coal today, and an obvious area which could contribute savings in world oil consumption. Oil bunkers are lifted fairly evenly throughout the world, the main supplying regions being Western Europe, the Middle East, North and Central America and Japan (Figure 1). Not surprisingly, the main customers are the tankers representing about 50 percent of the world market - (95 percent of the Middle East Market) - dry bulkers represent some 30 percent and general cargo ships the rest.

Jan 1, 1982

By M. Misra

The coral contaminated with plutonium at Johnston Atoll UA) was subjected to gravity and flotation separation processes at the Soil Washing Laboratory (SWL) and also at the Johnston Atoll UA) site. Tests were conducted with the contaminated coral fractions referred to as the "HP-l" ( hot particles) and the "sludge". The gravity process tested was centrifugal gravity separation and the flotation processes were conventional Denver mechanical flotation and tall column flotation. Flotation tests were conducted using both fresh and sea water. Industrial fatty acid (anionic collector) was chosen as collector to make plutonium-enriched particles hydrophobic. The use of flurosilicic acid and sodium silicate made the clean coral hydrophilic. The results show that each of the processed when tested with appropriate size fraction and operating conditions resulted in passing the success criteria. It was possible to obtain more than 80% weight of the original coral as "clean sand" having activity below the JA site "soil screening level" of 13.5 pCi/gm. The field tests spiked with plutonium particles showed remarkable success. The effect of depressants, flotation medium and the coral pretreatmentis described. Finally, a flowsheet developed by the University of Nevada, Reno to treat 8000 tons of HP-l pile presently stored at JA is presented.

Jan 1, 1996

By John C. Nixon

In 1959, The Australasian Institute of Mining and Metallurgy (Aus. I.M.M.) was asked by the Federal Government of Australia and the State Government of South Australia to join in the formation and management of a new contract research organization which was subsequently named The Australian Mineral Development Laboratories (Arndel) ? This body was formerly the Research and Development Branch of the South Australian Department of Mines which had been set up to develop the Radium Hill uranium deposit. It had then gone into contract R&D and the State felt that it would be more appropriate for the Branch to become a separate national organization. The Aus. I.M.M. decided that a professional institute could not participate directly in Arndel and, as there was no other suitable industry group to do so, it formed the. Australian Mineral Industries Research Association Limited (AMIRA). AMIRA held its first Annual General Meeting in September 1959 when the first Council was elected and the Memorandum and Articles of Association were adopted. The initial task of AMIRA was to raise guarantees of work or cash from its members to underwrite Arndel for the first five years of operation. The Federal and State Governments also provided guarantees and Arndel commenced operations in January 1960.

Jan 1, 1977

By S. -H. Kim

This work investigated the effect of the concentration of CO2 and lead contamination on the forest ecosystem. Changes of the plant growth, lead concentration in soil, plant, and soil microbial community caused by CO2 concentration (380 ppm and 760 ppm) and lead contamination (500 mg/kg) were measured. Plant growth was inhibited by 50% due to lead contamination. Particularly, shoot growth was inhibited more than the root. However, the root elongation was not affected by the CO2 concentration increase. The diversity of microbial population with AWCD (Average Well Color Development) and PCA (Principle Component Analysis) showed that the lead contamination has an effect com-pared to CO2 concentration. The Shannon index calculated from DGGE profiles was high in soil with Pinus densiflora, while the effect of CO2 concentration was not significant (P<0.5). The similarity of microbial community from each treatment showed that lead has an effect on plant growth and microbial community rather than the CO2 concentration.

Jan 1, 2006

By Eric C. Schwamberge, Clem A. Pelletier, Deborah L. Muggli, George W. Poling

The Pit Lake at Island Copper has evolved into a 3-layered meromictic system. Acid Rock Drainage (ARD) is collected and injected into the lake at 220 m depth via 2 diffuser systems. In situ dye studies were conducted during 2 differing hydrological regimes in order to determine the behavior of the ARD plume within the Pit Lake. Results indicated that when runoff from the waste dumps was low, the injected ARD remained within the bottom half of the intermediate layer of the Pit Lake, initially below depths of 90 m. However, when runoff from the waste dumps was high, the injected ARD at -220 m depth rose through the intermediate water column layer rapidly, but did not breach the top pycnocline at -10 m depth. Overall, the system is currently performing as a mixing bowl with a strong boundary or cap at the upper pycnocline. maintaining mixing below the 10 m depth water level.

Jan 1, 2000

By D. D. Murphy

The Bureau of Mines has studied the mechanism of shear-flocculation of silica with stearic acid. At pH 6 and 12, shear-flocculation of silica was not observed with up to 10-4M (5 lb/st) stearic acid. However, in the presence of 0.1 M NaCl at pH 6, shear-flocculation was observed at stearic acid concentrations 10-4 M (5 lb/st). Adsorption of stearic acid on silica was studied using stearic acids spin-labelled with a doxyl group. The presence of the spin-labelling group did not greatly affect the shear-flocculation properties of stearic acid. Adsorption of labelled stearic acid on silica was measured as a function of surfactant concentration with electron paramagnetic resonance (EPR) spectroscopy and gas chromatography (GC). The GC results indicate the stearic acid was predominately adsorbed on the surface at concentrations above 10-4 M. From the EPR spectra, the formation of aggregates of stearic acid was apparent at concentrations of approximately 10-414 (5 lb/st). The results are discussed in terms of a possible mechanism for shear-flocculation.

Jan 1, 1993

By Steven J. Schatzel, Mark M. Mazzella, Robert A. Kimutis, VASU GANGRADE, James D. Addis, Marcia L. Harris, Mayley Guitard

Researchers from the National Institute for Occupational Safety and Health (NIOSH) evaluated the impact of potential shale gas well breaches and subsequent gas inflow on selected mine ventilation systems of operating longwall panels using a 1:30 scaled Longwall Instrumented Aerodynamic Model (LIAM) and Sulfur hexafluoride (SF6) as a tracer gas. A series of tests were performed at 340, 400, and 500 cfm inflow levels utilizing different mine ventilation scenarios. Results suggest that the breached gas can be diluted to meet statutory levels when the longwall panel is adequately ventilated. The results enhance the understanding of the gas inflow and mine ventilation system interaction and provide critical information to the industry and regulatory agencies for improving miners’ safety.

Feb 1, 2024

By Thomas E. Browne

The Electric Power Research Institute Energy Supply Program is developing coal supply forecasts. By coal supply forecasts I mean the future relationships between coal price and production levels. A representative supply curve is shown in Figure l. It will make the rest of my presentation clearer if at this point I give you some background about EPRI and the Energy Supply Program. EPRI is funded by the nation&apos;s electric utility industry to develop new technologies for the production and conservation of electricity. Most of the research is conducted by outside contractors. We participate in joint projects with the Department of Energy and other organizations. The Energy Supply Program is one of three "economic" programs. The other two are Energy Demand and Conservation, and Systems. The Systems Program&apos;s main function is to provide the means to integrate the output of the other two Programs. The primary function of the "economic" programs is to provide information pertaining to future energy prices, availability, requirements, etc. to the EPRI personnel planning R&D programs. A secondary role that is becoming more and more important is providing information of direct use to the electric utility industry. I should note that the results of all EPRI&apos;s contract work are available to the general public. A "Coal Supply Analysis System" is being developed for EPRI by Charles River Associates. To the extent possible it will draw upon existing work, but much additional work needs to be done in the area of coal supply economics.

Jan 1, 1977