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Studies on coal mine drainage sludge densification have led to the following conclusions: 1. Coal mine waters containing iron principally in the ferrous (Fea+) state can be treated by a modification of the commonly practiced lime neutralization process to yield a ferromagnetic sludge. The sludge, presumably composed in large part of a hydrated ferrosoferric oxide (Fe304.xH20), is much denser and faster settling than the ordinary "yellowboy" sludge obtained by lime neutralization and aeration at ambient temperatures. 2. The magnetic sludge preparation technique involves (quantitative) precipitation of iron (largely as Fe(OH)2) by the addition of hydrated lime to a pH of 8.5, separation of the resulting sludge from the aqueous phase, and heating of the sludge concentrate to at least 80 C (176 F), preferably higher, followed by mild aeration. 3. Magnesium, present as Mg2 in most coal mine drainage waters, inhibits the formation of the magnetic sludge. This inhibition can be adequately minimized by keeping the pH below 9.6 during lime addition (thus avoiding the coprecipitation of Mg(OH)2) and by separating the sludge from the bulk of the aqueous phase before the heating step, as indicated in (2) above. 4. Aluminum, commonly present in coal mine drainage waters, also inhibits the formation of the magnetic sludge. This inhibition is of practical significance when the molar ratio of aluminum/total iron is greater than 0.18. Below this value, sludges are still appreciably magnetic, but are bulkier and slower settling than those obtained when aluminum is absent. Unlike magnesium inhibition, aluminum inhibition cannot be minimized by the scheme indicated above, since aluminum precipitates as Al(OH)3 near pH 4 and remains dispersed within the sludge. 5. The limitation on aluminum content is probably the most serious restriction affecting the feasibility of the magnetic sludge process as presently conceived. Nevertheless, a limited review of available water quality data has indicated that, in terms of relative acid and iron loadings, a significant number of major coal mine discharges in the eastern Ohio River basin may be amenable to treatment by a magnetic sludge process. 6. Data from tests on the use of magnetic seeding materials indicate that seeding did not enhance the formation of a magnetic sludge under the experimental conditions employed.

Jan 1, 1971

By Lloyd A. Morley, Alan M. Christman

Presented below is a review of how the objectives, as outlined in the statement of the problem, were achieved. 1. Methods of evaluating the performance of grounding systems must be described. These methods are the subject of Chapter III. 2. Field trips to operating mines should be undertaken, and a cri¬tique of their grounding systems made upon the basis of obser¬vation and the application of the above techniques. An analysis of field trip data, along with practical recommendations, is in¬cluded in Chapter IV, while a complete review of all field trips is given in Appendix I. 3. Because of their thoroughness, present coal mine regulations should be evaluated, and their applicability to open-pit environ¬ments appraised. This has been done in consultation with governmental agency, manufacturing, operating mine, and consult¬ing engineers. As stated in Chapter IV, insight gained through field observations has served to amplify and extend the base of knowledge from which the recommendations were made. 4. The results of these investigations should lead to suggested Federal standards. Such recommendations comprise Appendix II. In addition, several important factors, which are discussed in Chapter IV, were brought to light as a direct result of the field research. 5. Seasonal variations in the earth resistance of ground mats, as illustrated by Table 12, reinforce the need for periodic

Jan 1, 1976

By C. B. Manula, R. L. Sanford, R. A. Rivell

This report describes the development and application of a rail haulage simulator that is readily adaptable for the analysis of a wide variety of operating problems. Various gaming, options have been integrated into the model structure which permit trial and error solutions from a computer terminal prior to capital committment in the actual operation. The high level of information retrieval available allows engineers and managers to develop production data which fit individual needs. In this report, emphasis was placed on the problem of organizing and performing the sequence of operations that are necessary to accomplish a complete mine materials handling simulation. Here, the Rail Haulage Sub-assembly was linked to the Production Sub-system to mine and move coal from seven operating sections to the intermediate and main-line track. The analysis was devoted to the problems associated with how the operating system performs and what alternatives were available to minimize idle times and hence increase productivity. In order to have some objective means of evaluating which of the alter- native methods for production was most appropriate, the choice was to replace the intermediate track with belt conveyors. Since the attempt here was to demonstrate model flexibility and not to establish the goals or trade-offs between computing objectives with which systems judgement must contend, no further alternatives were tried. This is left to management with the data and a problem to solve. Rail haulage simulation is not new, and several, operationally tested models are being used in practice (Bucklen, et. al., 1968).

Jan 1, 1974

By Ronald D. Hill, Elmore C. Grim

1.In 1972 over 595 million tons (51+0 million metric tons) of bituminous coal were mined; 49% of this tonnage was obtained by surface mining methods. Authorities have predicted that the tonnage of surface mined coal will increase in the future, especially since oil and gas resources are becoming limited. 2. Demands for clean air have increased mining activities in the low-sulfur coal deposits in the West. Pollution problems arising from these operations will be considerably different than those found in the East. The deposits are located in arid to semi-arid regions. Coal seams are generally aquifers and are a principle source of fresh water. Therefore mining may result in alteration of groundwater distribution patterns by aquifer disruption. In general, pollution problems associated with western mining are not well characterized. 3.Since any disturbance of the surface will alter the environment in the vicinity of the disturbance, pre-mining planning is a prerequisite to any environmentally successful surface mining operation. If properly carried out, the adverse social, economic, and environmental effects of coal surface mining will be minimized. Certain land areas will be unsuitable for surface mining where: a.Reclamation is not physically or economically possible. b.Mining is incompatible with existing land use plans. c.The proposed mining area is of critical environmental concern. Core drilling is the most satisfactory method of obtaining accurate information for pre-mining planning. 4. Unaccountable strip mining in the past has created problems that are still present today. Contour mining methods that involve the indiscriminate dumping of overburden on the downslope is one of the largest single sources of sediment from strip mining. However, land disturbed by strip mining can be reclaimed. Techniques have been and are being developed by which mining and reclamation are integrated into a single operation. Mountain top removal, head-of-hollow fill, and block cutting are examples in contour surface mining. These methods drastically reduce pollution problems associated with contour stripping.

Jan 1, 1974

During 1990-1999, a total of 458 fires occurred in all coal mining categories; 157 of those fires caused 164 injuries and 2 fatalities. The greatest number of fues and fire injuries occurred at surface mines, whch also had the highest risk rate values. A total of 66 fuefighting interventions were required. Of these, there were 25 mine rescue team interventions in underground mines, including 5 mobile equipment firefighting interventions, and 41 fire brigade and fire department interventions at all surface operations, including 19 mobile equipment interventions. In all, 50 fires destroyed or heavily damaged equipment (including 16 pieces of mobile equipment) because of failure of other firefighting methods, late fire detection, undetected fires, or fire size. A total of 1 14 fires were detected late by smoke, and 42 fires were not detected.

By R. V. Ramani, A. S. C. Owili-eger

The rapid depletion of shallower coal reserves dictate that mining in the future will be deeper and more complex with more difficult natural conditions. Consequently, an increase in methane emission is expected. It is becoming evident that more accurate predictions and better planning are necessary to design efficient methane drainage systems. This objective can be achieved by the utilization of the knowledge of the physics of gas flow through coal seams and rock strata and by the application of digital computers in the solution of methane flow problems. Although the methane emission models described here have not been adequately applied to existing field operations, good agreement between actual field measurements reported in literature and the simulation results indicates the potential of these models for initial flow quantity approximations and ventilation planning. This report has, therefore, introduced to the mine operator yet another application of computers as a planning tool. AREAS FOR FURTHER RESEARCH The study reported here is by no means complete. Extensive research efforts should be directed to the following areas: (a) Better understanding of the physics of gas flow through porous media which exhibit fracture permeability. (b) Determination of field parameters which control gas migration. (c) Investigation of the effects of the rate of penetration on the emission rate and fracture propagation.

Jan 1, 1974

By Rudolf E. Greuer, Linneas W. Laage, Xinton Chang

The PC version of the program MFIRE contains many improvements and enhancements previously unavailable for the modeling of mine ventilation networks and the interaction of fires with mine ventilation Transient-state simulation with dynamic modifications of the ventilation system and mine, the fire, and resulting POC transport and ventilation alterations are accommodated with MFIRE. MFIRE is more flexible and provides more error checking, and more informational messages about prob¬lems with input files than its predecessor, the MTU-BOM code The desirable features of the MTU-BOM code such as calculation and identification of recirculation, the air to rock heat exchange, and the basing of calculations on mass flow rates have been retained. MFIRE is useful for the planning and analysis of ven¬tilation networks, simulation for emergency planning, and the evaluation of fire detector layout Inquiries relating to this program should be directed to the Bureau of Mines, Twin Cities Research Center, 5629 Minnehaha Avenue South, Minneapolis, MN 55417

Jan 1, 1990

In laboratory tests using reconstructed soil columns, rubber latex showed good sealing efficiency when applied at a rate equivalent to 4000-5000 pounds per acre. Results of field testing, however, were inconclusive. The ideal situation in which latex would coagulate in a narrow zone two to three feet below the surface by reacting with acidic or metallic constituents of the soil was not attained. Rather, the latex was deposited progressively as it passed through the soil (most of it remained in the top foot), the rate of deposition being dependent on soil structure and composition as well as on properties of the latex such as particle size and emulsion stability. Latex stability appears to be a more critical property than latex particle size in controlling penetration. Addition of excess anionic or nonionic surfactants to latex improved its penetration into the soil. A styrene-butadiene (SBR) rubber latex of 2400 Å average particle size with high mechanical stability gave the best balance of penetrating ability and sealing capacity in laboratory tests and this was confirmed in tests on a 5 x 5 foot test plot at Lanse, Pennsylvania. This latex was subsequently applied to three one-quarter-acre plots at Lanse by sprinkler irrigation, and compared to adjacent areas that were sprinkled with water only. Soil moisture measurements did not enable us to judge the effectiveness of the seal because differences between sampling positions were greater than differences between treated and untreated sections, but permeability tests showed that water flow was much slower (90-99% reduction) within the top ten inches of soil in the latex- treated sections. This sealing effectiveness was reduced after wintering. There was no deleterious effect on the vegetation as a result of sprinkling the areas with latex. A laboratory study conducted in a 5 x 5 x 5 foot box containing uniform reconstructed soil from a New Jersey source suggests that latex penetration into the soil in the field occurs mainly through natural macro openings and not through the capillaries of the soil structure. Dilute solutions of ammonium hydroxide or sodium carbonate (with no latex present) were found to seal effectively in laboratory soil columns as well as in field applications. However, since these chemicals are water soluble, the seal is temporary. Raw material costs of latex at the application rates used in the field testing are in the order of $1000 per acre. Equipment and operating

Jan 1, 1972

1. Mine drainage constitutes surface or ground water which flows from mines or mine sites and is usually characterized by concentrations of acidity or alkalinity. 2. The regional geology controlling the ground water flow pattern in conjunction with the life cycle mining plan can serve as a basis for making decisions about quality of water that can be expected to be encountered. 3. In regard to the prevention and control of acid water formation in underground coal mines, much is left undone in research and education: (A) Very little literature is available on this specific subject although much has been written on water management in underground mines. (B) Little or nothing is contained in the text books and curricula used in mining departments at colleges and universities with the result that educational offerings may be seriously deficient in these areas. 4. Prohibiting water entry into underground coal mines is the best method of preventing water pollution. Since this is not possible as mining operations are extended, preventing water or oxygen from contacting acid producing material may offer the next best alternative. 5. More emphasis is needed during the mine planning stage on steps to prevent water pollution. Such life cycle considerations as type of mining, sequence of development and spatial configuration as well as the elements of the drainage network and final network organization and extent must be considered.

Jan 1, 1970

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

A.5 Conclusions and Recommendations The illustrative simulations in the previous section have demonstrated 1. Flexibility of the program to simulate a wide variety of configurations and cases. 2. Ability of the program to predict evacuation time within a small margin of error (5 percent -.n a case considered). 3. Usefulness of the program in making some of the evacuation decisions. The above leads to a conclusion that the computer program can provide a useful tool in evaluating mine evacuation in the event of a fire. At present the program can be used to make decisions regarding evacuation scheme improvement, while the scheme is being studied. However, significant software and hardware developments are

Jan 1, 1976

By R Barritt

Remedial options for a waste rock dump (WRD) were considered as part of closure planning studies at an active mine in Western Australia. To minimise the impact of any seepage from the landform it was determined that placement cover system utilising the moisture ‘store-and-release’ concept was appropriate. The purpose of the cover system was to:•Reduce net infiltration of meteoric water to attenuate peak concentrations for contaminants of concern in natural receptors to levels that can be assimilated without adverse impact to the surrounding ecosystem; •Provide a growth medium for establishment of a sustainable vegetation canopy; and •Improve current quality of surface water runoff from waste storage areas.The project comprised several phases of work: materials characterisation, numerical soil-plant-atmosphere (SPA) modelling and finally cover system construction and monitoring equipment installation.CITATION:Barritt, R, 2018. Conclusions from long-term cover system performance monitoring – a case study, in Proceedings Life-of-Mine 2018, pp 101–105 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By Maria I. De Rosa

During 1990-2001, a total of 518 fires occurred in all metal/ nonmetal mining categories; 296 of those fires caused 308 injuries and 4 fatalities. Surface operations had the most fires and the highest injury risk rate values. Forty-five fires destroyed or heavily damaged facilities and equipment (including 19 pieces of mobile equipment) because of failure of firefighting methods, late fire detection, undetected fires, or fire size. In the future, many of these fires and injuries might be prevented or detected and extinguished at their earliest stage by improving current fire safety procedures, adopting existing/ improved fire detection and suppression technologies, and/or developing new technologies. Several strategies for reducing and/or preventing the number of fires and fire injuries follow. I. Increase vigilance, improve safety procedures, and develop new technologies in order to prevent fires and injuries caused by fame cutting and welding operations. 2. Improve equipment hydraulic/fuel/electrical systems inspection programs; adopt fire-resistant hydraulic fluids and electrically powered motors for use in underground mines; develop new technologies (equipment/cab rapid fire detection/ prevention/suppression systems, emergency line drainage systems, and fire barriers); adopt an optimal ground level location for the activation of emergency systems; improve operator's fire preparedness training programs; and develop effective and rapid local firefighting response capabilities. 3. Adopt existing/improved systems for continuous and early detection of combustion gases and smoke along beltlines. 4. Adopt existing/improved technologies for monitoring equipment (beltlines) operational functions. 5. Increase vigilance and adopt improved safety procedures for handling f amenable liquids and refueling fuel in the vicinity of heat sources.

Jan 1, 2004

By M. J. Sanzotti, C. J. Bise

This paper examines the potential for controlling longwall-induced subsidence by pneumatically backstowing waste rock into the void created by mining. The paper also examines scheduling the process as a unit operation of the mining activity. Based on a review of background literature and interviews with representatives of various mining companies, public-interest groups and state and federal regulatory agencies, a hypothetical case-study evaluation of pneumatic stowing at a southwestern Pennsylvania mine was conducted. The study indicated that current stowing technology cannot keep pace with the production potential of longwall systems in the United States. Further, at the mine used in this case study, concomitant stowing would reduce subsidence by only 50% of what would normally be incurred during full longwall caving, and the longwall coal-production rate would decrease from 3,630 t (4,000 st) per shift in the nonstowing case to 1,360 t (1,500 st) in the stowing case. A preliminary cost analysis reveals that pneumatic stowing would add from $5.79 to $11.57 per t ($5.25 to $10.50 per st) to the operating cost of producing coal at the case-study site.

Jan 1, 1997

By M. J. Sanzotti

This paper examines the potential for controlling longwall-induced subsidence by pneumatically backstowing the void created by mining with waste rock, and having the process scheduled as a unit operation of the mining activity. Based on a review of background literature, interviews with representatives of various mining companies, public-interest groups, and state and federal regulatory agencies, a hypothetical case-study evaluation of pneumatic stowing in a southwestern Pennsylvania mine site was conducted. The study indicated that current stowing technology cannot keep pace with the production potential of U.S. longwall systems. Further, at the case-study mine site, concomitant stowing would reduce subsidence by only 50% of that incurred during full longwall caving, the longwall coal production rate would decrease from 4000 tons per shift in the non-stowing case to 1500 tons in the stowing case, and a preliminary cost analysis reveals that pneumatic stowing would add $5.25 to $10.50 to the operating cost of producing a ton of coal at the case-study site.

Jan 1, 1995

By Warren G. Burres

or more than 50 years the Portland Cement Association has represented the United States cement industry in matters relating to the technology and use of cement and concrete. Interestingly enough, PCA?s emphasis has been on concrete and its uses rather than on Portland cement. The cement industry realized long ago that cement is basic and serves its fundamental purpose as an ingredient in concrete. Cement could never be successful if concrete were not. Work with the users and specifiers of concrete had to be done at its end point of application--in a building, bridge, dam, highway or home. PCA, over its half century of existence, has been dedicated to this job. I should like to talk to you today on the less technical side of concrete--what it has been--what it is today--and what it can offer in future construction. Concrete, in many forms, has a long background extending from such notable historic times as the Roman Empire. Here, concrete made from pozzolanic cement from the slopes of Mt. Vesuvius was used to construct the Coliseum, home of the Roman circus; for the Appian Way, the ancient forerunner of the Interstate system; and the miles of aqueducts throughout Europe, many of which still carry water. In 1811 Joseph Asppin, an English bricklayer, made the first modern cement by the artificial mixing of pulverized limestone and clay materials. Ht,

Jan 1, 1971

By P. J. Routledge

THE purpose of this paper is to discuss the practical aspects of locating gravel deposits and of establishing efficient, portable concrete aggregate beneficiation plants for use on construction projects where limited amounts of high-quality gravel and sand are required. Certain projects are listed, in order to demonstrate the wide variety of problems encountered. Routledge Gravel Contractors Limited, North Vancouver, have supplied concrete aggregate for construction projects in British Colum-bia since 1957. In tl1at year, in sup-plying aggregate for a small project at a site on the northern coast of British Columbia, our quote was as follows: Concrete aggregate to specifications, f.o.b. scow, North Vancouver$ 1.75 per cu. yd. Scowing charges to site. $16.00 per cu. yd. At that time, our company realized that more attractive quotations could be submitted if local gravel was utilized where available. Port-able equipment was then acquired and a simple screening plant (Figures 1 and 1a) was at first used. This was later replaced by heavier, more versatile equipment. The use of suitable equipment, the keeping of cartage to a mini-

Jan 1, 1962

By J. L. Bruce, G. W. Nicolson

THE country rock of the Mavrovouni mine of the Cyprus Mines Corp. is hydrothermally altered, disintegrated pillow lava, with very little tensile strength ("short" ground). In places, especially when wet, it is heavy ground, though not extremely heavy except where movement has been caused by underlying or nearby stoping operations. Damage by caving from roof or sides of galleries is not sudden but progressively faster when the size of the cave increases as a result of the fall of small pieces. CEMENT AND CONCRETE LININGS During early operations, galleries in the country rock were supported by customary mine-timbering methods. Available timber, however, was of poor quality and of relatively high price, and replacements were frequent and expensive. Furthermore, the massive sulphide ore bodies required large volumes of fresh air for ventilation and cooling, and it was therefore desirable to provide smooth-lined galleries with low resistance for the introduction of air to the ore bodies. It was also desirable to eliminate hazards of fire in shafts and underground workings insofar as this would be practical. Cement and concrete were relatively cheap, and plans for using these in support of shafts, underground galleries, raises, and chutes, were developed steadily. Circular shafts with diameters ranging from 10 to 15 ft were adopted for all permanent shafts and airways. In places these were lined with concrete poured behind sectional pressed-steel forms especially constructed for this purpose. In other places, they were lined with precast-concrete blocks. It was found that such precast concrete of good quality could be produced on mass production scale and delivered at the mine from most favorable point of manufacture, at a cost of about 25 cents per cubic foot of concrete. This refers to prewar costs. As the use of concrete blocks in circular lined galleries was developed, it was found that there were very great advantages in the reduction of air resistance as compared with customary timber supports. After best methods had been developed, it was found that breakage and replacements were extraordinarily low, averaging only about 1 ½ pct per year during a period of about 15 years. Furthermore, it has been possible to reclaim for re-use a very large percentage of the concrete blocks from abandoned galleries. During the history of the operations precast-concrete blocks have been used for lining shafts, raises, ore chutes, galleries, and shaft stations, ranging from 3 to 16 ft id. The thickness of lining has varied from 5 to 10 in.; with I2 in. thickness in a few cases. Junctions of two galleries at angles ranging from about 30 to 60° are usually made of poured concrete behind sectional forms, or of a combination of poured concrete and precast blocks. In nearly all cases it has been found advisable to make the point of the wedge at the junction, of

Jan 1, 1947

By Paul Kunze

When a new bridge was needed across the upper reaches of the Yellowstone River in Montana, removing the old concrete bridge piers became an environmental concern for the highway department engineers. The location is about fifty miles downstream from the north edge of Yellowstone Park. The determination was made by the federal and state agencies charged with protecting the resource, that the old piers had to go but the river bed had to remain unchanged. Concerns were expressed that removing the concrete presented the potential for environmental damage to this protected portion of the river. These concerns prompted the state to place stringent restrictions on the contractor in the way they carried out the demolition and disposal of the piers. The reinforced concrete masses had to be removed to an elevation at least fifteen feet below the river bed and every bit of concrete debris had to be removed from the river channel. Explosive removal was discouraged, but the only other options: saw cutting, mechanical or chemical breaking, were not viable.

Jan 1, 2014

By D. Wenstrup, K. Perry, J. Hatfield, P. Sainato, B. Lusk

Concrete-infused cloth is used in several civil and mining surface applications whose circumstances are similar to some of those in underground mining. A feature of this material is that it cannot be overhydrated. In underground conditions, however, the excess supply of water to the cloth for hydration could lead to muddy and potentially unsafe working conditions, as well as resource wastage by supplying more water to the construction site than is needed. The objective of this study is to verify the water-to-cloth ratio and study the effect of hydration level on the strength of the Concrete Cloth product. We found that the strength increases with increased hydration up to a 1:2 water-to-cloth ratio by weight, after which the strength holds steady regardless of additional hydration. This confirms the 1:2 water-tocloth ratio by weight for hydration and confirms that strength is retained even if the cloth is excessively hydrated.

Jan 1, 2014

By L. C. DeCory

"Concrete is a common denominator to the building process and portland cement is an integral and necessary component of concrete. The cost of portland cement is nominal and its cost comprises, in most instances, a small portion of the total cost of ""put-in-place"" concrete.The domestic demand for portland cement in Canada is projected to be slightly less than 11 million short tons in 1980. In order to achieve this projected goal, stabilization or lowering of the cost of put-in-place construction is necessary. This enhancement of the cost of building can be achieved by:(1) improving the building process;(2) refining and improving design techniques; and(3) developing improved and economical concrete products.Some of the techniques and materials that will lead to building cost stabilization include systems building in its broadest sense, slipforming, precasting, prestressing, computer design, lightweight aggregates, fibrous concrete and integration of building components."

Jan 1, 1973