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By J. Szlazak, A. Tor, M. Borowski, N. Szlazak, D. Obracaj

This article presents the analysis of ventilation systems used in dead-end headings, while being drilled, in coal mines. Special emphasis is put on methane and dust hazard. Mathematical model for distribution of methane concentration in a heading is given as well. This model takes into consideration sources of methane emission and change in air flow rate due to leaks in a duct line. Solving equations presented in this article enabled giving dependencies describing distribution of concentration along the heading. On the basis of these dependencies there is a possibility of determining places with higher methane concentration and ways of combating this hazard. Determining the distribution of methane concentration in dead-end headings ventilated by a separate ventilation system is of great importance as far as work safety conditions are concerned. The information obtained may be of use when finding proper places for installing methane sensors. Three kinds of separate ventilation systems were distinguished: forcing, exhaust and overlap. The development in construction of fans and spare parts of a duct line enables using both forcing and exhaust ventilation systems in headings developed by continuous miners, with length above 1000 m, in the conditions of methane, temperature and health-detriment dust hazards.

Jan 1, 2003

Paiam is a new township in the high mountains of Papua New Guinea built in association with the Porgera Joint Venture mine, one of the world's largest and most remote open cut gold mines. The Paiam town project is an interesting and genuine attempt at building sustainability into a community associated with a mine. A result of a tri-party agreement between a resource developer, government and land owners, this town is a good example of appropriate utilisation of benefits, obtained from resource development, directed at achieving a sustainable environment at local and regional levels.   Mining brought technology and income to the region, although as most mine staff fly directly in and out, local landowners considered there was a limited flow of benefits within the nearby townships. An agreement with government and mine was reached that more mine personnel and their families be housed locally. In 1998, we, a firm of Landscape Architects and Heritage Consultants based in Cairns, Queensland, were engaged to assist develop the fledgling town of Paiam into a livable and sustainable town and to produce material that would convey that information to stakeholders.   The design focused on establishing a sustainable town, with livability, urban form, aesthetics and opportunities for economic, social and cultural development. Aiming to be a livable town for locals and mine staff it included a market place designed as a focus for town life, essential for social cohesion and economic opportunities.   Located at 2200 m on steep rainforest clad topography, the town development has been laid out using an appropriate urban form based on organic village layouts. Clusters of houses allow for a common public area so children's play is monitored assisting with a sense of community similar to a traditional defensible village. Aesthetical consideration helps in developing community pride whilst maximising potential for development of a tourist industry.   Opportunities for ongoing economic development were incorporated in the design and construction process. These included developing skills and trades to service the region and to provide skills, development, income opportunities and infrastructure to last beyond mine closure. Administration procedures were set in place to form the basis of good governance.   The shift from traditional subsistence lifestyle to a sustainable community with traditional attributes was the project's goal and is being achieved.

Jun 1, 2010

By Terry Keough

Contents for discussion ?Current liner technology ?Innovation of magnetic products ?Development of magnetic wear liners ?Installation and change out method ?Uses and capabilities ?Internal wear liners ?Summary Vulcanized rubber ?Many of you are familiar with using vulcanized rubber to provide wear protection on mining equipment. For years, this was the standard for most mining equipment, and mines spent a lot of money fabricating and lining steel equipment.

May 1, 2010

That electricity is an important and valuable agent, the limit of whose capacity for utilisation is as yet unknown, is a truism; although enormous advances have been made, the possible developments are yet greater. Mining, along with other industries, shares already to a large extent in the practical utilisation of this agent. Electrical engineers have been employed for several years past in developing and applying electricity to all classes of machinery, and for every purpose where power is required and in no instance, that the writer is aware of, has its use been curtailed in favour of any other agency now known, while extensions are continually made. The first modern electric motor was shown at the Vienna Exhibition of 1873, and it was used to work a pump through a mile length of cable but it was not before 1878, that an electric motor was put into daily commercial use by Messrs. Chretian and Felix to work a beet sugar hoist. This early plant effected a saving of 40 % as compared with hand work.In 1879, the first Electric Railway was constructed for the Berlin Exhibition, and in the same year, Mr. T. A. Edison was running an experimental line at Menlo Park. The first electric line opened for the public, was constructed by Siemens and Halske, in 1881, at Lichtenfelde, and was 11 miles in length.

By R. C. Earlougher

Jan 1, 1970

By Dale S. Preece

A Discrete element computer program named DMC @istinct Motion Code) has been developed for modeling rock blasting. This program employs explicit time integration and uses spherical or cylindrical elements which are represented as circles in 2-D. DMC calculations have been compared with measurements on bench blasts in the field with relatively good comparison. Structural rock mass characteristics have a significant impact on any blast and DMC has not, until now, included these effects. This paper discusses a recently added DMC capability for treating joints and bedding planes in bench blast simulations.

Jan 1, 1995

By Paul H. Lu

This Bureau of Mines report summarizes the analysis and eveluation of the field measurement results of a comprehensive ground control study conducted in a mechanized longwall coal mine in West Virginia. Emphasis is placed on the three basic ground control parameters: ground pressure, ground movement, and geomechanical properties. Specific topics include premining ground pressures, front-abutment pressure in the longwall panel, histories of pillar loading, differential roof-strata movement and bed separation, differential floor strata movement, entry roof-to-floor convergence, in situ moduli of rigidity of coal seam and roof and floor strata, and mechanical properties of coal and coal measures rocks.

Jan 1, 1985

By Dean McDonald

The Committee Bay Greenstone Belt extends over 300km and is one of the largest unexplored greenstone belts in North America with excellent gold and diamond potential. Committee Bay Resources Limited holds over 550,000 acres of land with prospective geology in the Committee Bay area southwest of Melville Peninsula, Nunavut. Committee Bay is a typical Archean greenstone belt comparable to the Yellowknife, Red Lake, Kirkland Lake and other prolific gold belts. Drilling during 2003 at Committee Bay resulted in: 1) the discovery of high-grade gold-bearing quartz veins with silicification and sulphidation at Three Bluffs, and 2) the continuation of high-grade gold mineralization in the hinge area of the iron formation at Inuk. Gold mineralization at Three Bluffs is identified in iron formation and adjacent sediments and has been traced by drilling for over 700m. The Three Bluffs iron formation is open to depth and along strike where is has been traced on surface for over 6km. In January 2004 Committee Bay and joint venture partner Gold Field?s announced a $7.1 million exploration program for the Committee Bay project in 2004. A total of 8,000m in exploration drilling has been approved for the expansion of the Three Bluffs to the resource stage and drilling of at least five new target areas. Additional mapping, sampling and geophysics will be used to identify new gold targets along the very prospective Committee Bay belt.

May 1, 2004

By Kenneth S. Johnson

Oklahoma is the only; state in the nation that is currently producing iodine. The iodine is extracted from iodine-rich natural brines being pumped from deep wells drilled into Pennsylvanian sandstones in the Anadarko basin of northwestern Oklahoma. Woodward Iodine Corp., started in 1977, was the first plant in the United States built for iodine recovery since the 1930s. At present, three companies are operating four iodine-producing facilities in northwestern Oklahoma. The combined production of these facilities, 1,321,000 kg in 1997, is about 26% of the U.S. annual consumption. Iodine is present in concentrations ranging from less than 100 ppm (parts per million) to as much as 1,560 ppm in brines in various Paleozoic strata in the subsurface of northwestern Oklahoma; these concentrations are exceptionally high, and are well above those of any other known brines in the world. Strata with the highest iodine content in the area (Mississippian limestones) have low permeabilities, and thus would yield only small amounts of brine. On the other hand, the lower Morrow sandstones (Lower Pennsylvanian) have a relatively high permeability and are capable of yielding large quantities of brine that average 300-350 ppm iodine. The Morrow brine reservoir was deposited in shallow-water-marine and intertidal-shelf environments and now is buried 6,000-10,000 ft below the land surface. Production is localized to Morrow channel deposits confined to an Early Pennsylvanian paleovalley that is 1-2 mi wide, is about 70 mi long, and is referred to informally as the "Woodward trench." All three companies are producing iodine-rich brines from Morrow sandstones in three different parts of the Woodward paleovalley, and one of the companies also is extracting iodine from oil-field brines coming from several petroleum reservoirs near Dover, about 80 mi east of Woodward. The basic extraction method employed by Woodward Iodine Corp. was used in Louisiana and California operations in the late 1920s. This method is commonly called the air-stripping process. Lower Morrow brine containing dissolved sodium iodide is pumped to the plant through a series of pipelines, where by-product natural gas is separated and processed. The brine is then acidified and subsequently oxidized with chlorine to convert the iodide to iodine. The iodine is air stripped and reabsorbed with sulfur dioxide and water, converting it to hydriodic acid, or process liquor. The process liquor is then processed, using chlorine once again, to crystallize the iodine as a solid. This is then melted and frozen to form a solid product, which is packaged in 110-lb (50-kg) drums and shipped to end users throughout the world.

Jan 1, 1999

By Paul M. Wiltcher

This paper discusses how benefits in engineering design can be achieved from combining existing GRP concrete design guidelines with carbon steel design codes primarily made possible due to the increase in the constitutive properties of modern composite rebar or GRP. It also examines the technical and practical considerations necessary to both construct and ensure the integrity of composite rebar during transportation and handling on site and the measures taken by Franki-Cementation Joint Venture to ensure the safe deployment of the GRP in the workplace on the Noord/Zuidlijn Project in Amsterdam between 2003 and 2006.

Jan 1, 2006

By Peter N. Blakey

The Kidd Creek orebody is a massive, base metal deposit with widths up to 600 feet and a strike length of 2,200 feet. The orebody dips eastwards at 70° to 80° and is amenable to sub-level open stoping. Five distinct zones (Fig.1) based on structural wall rocks and ore type parameters occur within the orebody. These zones are: Zone 1 - Mainly copper stringer ore Zone 2 - Massive pyrite ore Zone 3 - Massive sphalerite and chalcopyrite Zones 4 and 5 - Are banded and variable in nature Compressive strengths vary from zone to zone with an average of 22,000 p.s.i. and highs of 40,000 p.s.i. The mine is developed from a ramp extending from surface to the 1600 foot level and a 24 foot diameter, 3050 foot vertical shaft with main levels at 400 foot intervals. Sub-levels at 100 foot vertical intervals are driven from the ramp. transverse and longitudinal pillars to support the crown pillar left under the open pit. The layout allows an opportunity to enlarge or reduce pillar sizes and also to introduce fill on any horizon should conditions warrant. It also offers a large number of operating stopes spread through the various ore zones giving good ore blending characteristics. All ore from the stopes is handled through drawpoints using Wagner ST8 scooptrams with an average one way haul length of 650 feet.

Jan 1, 1976

By G. Segaetsho

"Conventional blasting rules of thumb used to develop blast designs are based on parametric ratios, with insufficient consideration of the rock mass factors that influence the achievability of final wall designs. At a hard-rock mine in Botswana, catchment berm designs were frequently unachievable, which exposed the mining operation to safety hazards such as local wallrock failure from damaged crests, frozen toes, and rolling rockfalls from higher mining levels. Increased standoff distances from the highwall reduced the manoeuvring area on the pit floor and the extraction factor that was safely achievable. Application of rock mass classification and the Blastability Index (BI) as a means to improve wall control was investigated. Zones were defined according to rock types forming the western highwall rock mass, and distinguishing rock mass classification factors were used to establish the suitable wall control designs. The approach combined rock mass classification methodologies such as the Geological Strength Index and the Rock Mass Rating, and related them to the BI and discontinuities of the rock mass to produce a design input tool that can be used to develop objective wall control designs. The designs driven by the tool inherently take into account the rock mass characteristic factors at the centre of the rock mass classification methods mentioned above, and significantly reduce the dependence on rules of thumb. It was found that this approach produces designs with explosive energy measures that are consistent with the required rock-breaking effort and the behaviour of discontinuities, while preserving perimeter walls.IntroductionBlasting is the first step in the comminution process. Various coordinated inputs contribute to its success, and in turn to the efficient execution of processes that lie downstream from the blasting step. Primary to meeting production and operational objectives of a mine, as well as the protection of human life and the mineral resource, is the achievement of highwall design specifications and competence. To this end, this study investigated the use of existing tools and knowledge for the achievement of highwall control goals at a hard-rock mine in Botswana."

Jan 1, 2018

By K. Bruce Hodgins

The North American mining industry faces challenging emissions regulations in coming years with the introduction of new standards for off-road diesel engines. In order to remain competitive, industry stakeholders must invest in new technologies that are economically and environmentally sustainable. Westport Innovations Inc., of Vancouver B.C. has developed high pressure direct injection (HPDI) technology that allows diesel engines to run primarily on natural gas with no intrusive engine modifications, reduced emissions of NOx, PM, and CO2, with no loss in performance. This is accomplished through late-cycle high-pressure injection of natural gas directly into a diesel engine combustion chamber. The natural gas is injected at the end of the compression stroke. A small amount of diesel fuel is injected first to initiate combustion, followed by the main natural gas fuel injection. The diesel cycle and its operating characteristics are fully retained including high combustion efficiency, low speed torque, high-power output, no engine knock and fast response to load changes. Natural gas has not been an attractive fuel alternative in mining operations due to reduced performance associated with spark ignition engines and the added weight and space required for compressed natural gas tanks. However, liquefied natural gas (LNG) can be stored in a similar manner and volume to diesel fuel by virtue of its increased energy density over compressed natural gas. Cummins, Inc. of Columbus, Indiana and Westport have formed a joint venture, Cummins Westport Inc. (CWI), under which agreement the HPDI technology is being applied to a Cummins QSK engine series for high horsepower applications such as mine haul trucking. CWI, along with Komatsu Mining Systems, ENRG Fuels, Placer Dome, and Cortez Joint Venture are performing a feasibility study for the development and demonstration of an LNGfueled HPDI QSK engine in a large mine haul truck. The goal would be to demonstrate low emissions consistent with EPA ?Blue Sky? standards, high efficiency based on HPDI technology and good economics resulting from the high fuel consumption of 2,000+ hp trucks.

May 1, 2002

By J. L. Konchesky

In gasifying pulverized coal with steam and oxygen, the particle size of the coal fed to a gasifier should be as small as economically possible. A potential way to achieve this advantage is to reduce the particle size of the coal by passing the coal-steam mixture at high velocity through a heated tube coil before the mixture enters the gasifier. To evaluate this method the Federal Bureau of Mines flashed coal-water slurries in externally heated metallic tube coils to determine the extent of size reduction. The first of two different laboratory-scale apparatus reduced the average particle diameter of subbituminous C coal from 190 to 110 microns at an outlet velocity of 330 feet per second (f.p.s.). At the same outlet velocity, a second apparatus reduced the average particle diameter from 250 to 140 microns. An increase in velocity produced more finely divided coal, but variation in temperature and pressure had no effect except as they affected velocity. Virtually the same size reduction was noted for five ranks of coal at equal velocities. The rate of increase in particle-size reduction with increase in velocity decreased with a decrease in particle size. The pulverizing mechanism was concluded to be abrasion of the particles with each other and with the tube wall.

Jan 1, 1961

By George A. Morrison

THE Columbia Chemical Division of the Pittsburgh Plate Glass Co. is at Barberton, Ohio, 35 miles south of Cleveland. For many years large tonnages of limestone have been brought to the Barberton plant from distant points. The stone is here burnt in vertical kilns, the resultant product then hydrated and the hydrated lime used in chemical processing. To eliminate the expense of these shipments, the company decided to investigate a limestone bed known to exist on company property at Barberton, where the stone is used. The bed lay at a depth of more than 2000 ft. and was known locally as the "Deep Lime." Chemical analyses of sludge from churn-drill holes made some years ago proved that the limestone was of sufficient purity to warrant diamond-drill exploration. Four diamond-drill holes were put down at well-spaced intervals, to represent fairly an area of four miles by one mile. Cores logged as to chemical and physical conditions were found to compare closely, and to corroborate the earlier evidence that the limestone was of superior quality for chemical use. A plant of 300 tons per hour was subsequently decided upon. SITE The yard at the chemical plant was already so congested that location of the projected mine within its area could not be considered. Eventually a site was selected 2 miles northwest of the plant, near the main line of the Erie Railroad. Here 412 acres were owned outright by the company and stone rights were obtained on 250 additional acres. This location required a transportation line of nearly 2 miles (8800 ft.), crossing two major highways, and to avoid interruption of deliveries to the plant, overpasses were planned. GEOLOGY The limestone in the immediate vicinity lies about 2200 ft. below the surface. Geologists* identify this stone as Delaware of Devonian age. It is overlain by 18 ft. of unconsolidated (sand and gravel), 100 ft. of water-bearing sandstone, and finally 2080 ft. of shale into which sandstone in thin layers is interbedded. The contact of shale and limestone is abrupt, flat-lying and very pronounced. Berea sandstone, often found at 520 ft., is absent, but Euclid sandstone was encountered, together with a seepage of oil and a small amount of methane gas. The limestone bed itself is 345 ft. thick, and overlies 200 ft. of gypsum. The lower part becomes dolomitic as it approaches the gypsum. A detailed study of the drill cores indicates that the upper 50 ft, are highest in lime and reasonably low in silica. The physical make-up shows several separating cherty layers. These occur at definite horizons and cause distinct partings, which become horizontal planes of

Jan 1, 1943

How Particles Stick to Bubbles - The Influence of pH and Hydrophobicity in Flotation

Sep 13, 2010

By X. Ndlovu

Underground observations in a coal mine have indicated failure oft he immediate roof above the bords. Careful observations and photographic recording of occurrences of these roof failures, termed ?roof guttering?, have been made. The occurrence of guttering results directly in roof instability, and indirectly, due to the interaction of the guttering with natural planes of weaknesses in the immediate roof rock. In this paper, relevant observations of roof guttering, possible mechanisms of formation of roof gutters, laboratory testing for determination of material strength and deformation properties, and numerical analyses to explain underground observations are described. Mapping of roof failures showed that these took place mainly towards the centre of the roadways. Roof guttering was observed often to occur violently and with little warning. Occurrence of roof guttering has a negative impact on production?some panels are abandoned, production times are increased and safety of workers is compromised. The numerical stress analyses showed that, although none of the constitutive behaviour criteria used predicted the observed underground failures correctly, the extension strain criterion gave the best agreement.

Jan 1, 2007

By D. G. Westlake

Levine has concluded that prismatic slip in titanium is controlled by two distinct thermally activated processes in the temperature ranges O° to 220°K and 220" to 300°K. We feel that his evidence is not convincing. He has drawn a curve through the plot of activation volume u* vs temperature T with a break at 22WK, Fig. 2. We believe that considering the possible experimental error apd the fact that there are only four points between 4° and 196°K, one could be justified to represent these points by the smooth curve we show as a solid line in Fig. 12. Levine believes that (8rf/aT)+ is discontinuous at 220°K, but he hints that he recognizes the possible doubt. We doubt seriously that the results shown in Fig. 1 indicate a discontinuity at 220°K. Certainly if he were justified in drawing a straight line through only four points on Fig. 2, we are even more justified in drawing straight lines through the seven points between 77" and 297°K on Figs. 1 and 3, because a straight line touches all seven of his circles. If his measurements of t were so precise that his decision to draw two curves in Fig. 3 is valid, then the experimental technique is deserving of further mention. We have drawn a smooth curve through the results in Fig. 3 and used this and the curve in Fig. 12 to obtain the values of shown in Fig. 13. Finding continuous is a contradiction of Fig. 4, which deserves comment itself. Levine obtained the solid circles in Fig. 4 using Fig. 2 and a smooth curve through the points shown in Fig. 3. We have replotted these solid circles in Fig. 14. We submit that there is no basis for his two straight lines (dashed in Fig. 14), and therefore have superimposed the curve that we believe is indicated. Certainly, there is reasonable doubt that a discontinuity in dH/dT exists at 220°K, even when one accepts Fig, 2. Furthermore, if one draws the straight lines indicated by least-squares treatments of the results presented as open circles in Fig. 4, their intersection is at about 196°K, not at 220°K as shown. Thus the alleged agreement between Figs. 3 and 4 with respect to "break" temperatures is not apparent. In Fig. 9, Levine has drawn a straight line very much different from the one indicated by a least-squares treatment. Obviously, he has done this because he recognized that H = 0 when T = 0. He is consistent in drawing the low-temperature curves in

Jan 1, 1968

By B. A. Osei

Research to evaluate possible metrics for predicting dredgeability of compact aggregates, by hydraulically actuated clamshell dredges, shows work done by the pistons as a viable metric. Analysis of field data shows that there is a low, positive, correlation between cycle time (CT) and work done. If this correlation exists, then CT has to be considered an independent variable affecting work done during dredgeability assessment. Further research is required to elucidate the relationship between CT and work done during dredging. The objective of this paper is to test the hypothesis that work done during dredging increases with increasing CT. Kinematics and dynamics of the hydraulic clamshell were modeled and implemented in Simulink® in MATLAB. The model was validated using field data. The model was then used to test the research hypothesis. The results show that work done increases with increasing CT. This work confirms that work done during dredging increases with increasing CT. This result indicates that though an operator can increase the CT to deal with difficult digging, inputting unduly high CTs results in higher energy consumption during dredging.

Jan 1, 2011

During a mineral exploration program in an environmentally sensitive area nearMount Painter in South Australia, a helicopter was used to position, construct and service drilling rigs in order to avoid the need to create new access tracks. The drilling program was designed to optimise the advantages of natural landforms in order to minimise the environmental impact of site construction and drilling activities. This minimisation of land disturbance reduced the required amount of rehabilitation measures to the extent where all impacts of the helicopter-supported programme had disappeared within 12 months of completion of work.

Jan 1, 1995