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By B. J. Arnold, F. F. Aplan, S. Chander

There is a broad range of chemical reagents of potential use to the coal preparation industry: flotation frothers, flotation collectors (for coal, ash minerals or pyrite) and collector-assisting (conditioning) agents, flotation depressants (for coal, ash minerals or pyrite), pH regulating agents, acid mine drainage treatment chemicals, flocculants, filtration aids, dispersants, dust suppressants (wetting agents and car-top or pile binders), freeze conditioning agents, water treatment chemicals (corrosion and scale inhibitors) and suspension stabilizing reagents (dispersants, stabilizers, biocides). The application of each of these types is discussed with particular attention paid to those of greatest importance: flotation frothers and collectors, pH regulators and acid mine drainage treatment chemicals, flocculants and freeze conditioning agents.

Jan 1, 1986

By Jan Wolski, Jack Barry

Ventilation ductlines with a single fan or with a series of fans are analyzed. The duct friction loss factors are discussed. Numerical solutions, presented in the paper, applies to any fan number and locations along a duct line. The findings are compared with formulas available in the technical literature. Values of the air leakage factors are presented in the SI, technical metric, and US unit systems. A method is shown of how to determine the leak- age factor for a given ductline. Optimum solutions for the sample duct lines with two and five fans in series are discussed and presented in a graphical form. Performance of fans in series is discussed in conjunction with both friction pressure loss and leak- age.

Jan 1, 1997

By Hardy J. Smith

The rock mass parameters which need be evaluated to estimate the rippability of rock are briefly outlined and their significance is discussed. Several methods used for estimating rippability are compared, and the advantages of taking into account a wide spectrum of rock mass parameters are emphasized. A systematic means of numerically weighing six rock mass parameters to produce a Rippability Rating (RR) is recommended, and a method of correlating this rating with the refraction seismograph method and with tractor horsepower is shown. Although the overall method demonstrated is systematic and yields specific numerical results, an integrated approach is recommended to its application, taking into account: the Rippability Rating; seismic velocity and geologic material; and other engineering judgment factors.

Jan 1, 1986

By S. S. Peng

Horizontal stress is an important factor that contributes to roof failure during longwall entry development, especially when the immediate roof is weak. In this paper, the effects of stress angle between the maximum horizontal stress and entry development and stress ratio of the maximum to minimum horizontal stresses on the stress distributions in the weak immediate roof of a three-entry system are analyzed using the finite element method. The results have confirmed that stress angle has a significant influence on the stress distributions. Generally, the three-entry system is in the worst stress condition when the stress angle is about 60° to 75° . The stress ratio has also some effects on the roof stresses.

Jan 1, 2000

By Y. J. Wang

A subsystem-based approach to the characteristic curves for a multiple fan ventilation system is presented. The ventilation variables and their relationships associated with a fan branch are considered as a subsystem of the multiple fan system. For each subsystem, the solution curve is generated by replacing the fan with a hypothetical pressure source or, alternatively, by adding a hypothetical pressure source without removing the fan. The projection of the solution curve onto the coordinate planes results in two classes of subsystem characteristic curves: pressure-vs.-quantity and quantity-vs.-quantity. The subsystem characteristic curves are described and illustrated through example ventilation systems. These curves are also discussed using the network equations of a general multiple-fan system.

Jan 1, 1993

By Tom C. Palanglo, Norbert Maerz

Control of crushing and grinding circuits ideally requires continuous particle size measurements on both in- and outgoing streams. Until recently, size distributions could only be obtained by screening methods, which were neither cost effective, frequent enough, nor timely. Input streams are often composed of large fragments, making screening prohibitive. Optical image processing systems, such as the WipFrag System, have been developed to the point that they are an extremely valuable tool to characterize, control, and fine-tune the comminution process. Although accuracy is less than that of screening, measurements are precise enough to detect relatively small changes in size distributions.

Jan 1, 2000

By Dilip K. Sinha

In the paper some interesting cases of applications of Operations Research and Computer Methods as worked out by the author and accepted by the management of some of the newly formed Indian mining organisation for implementation are highlighted. The main emphasis on the application cases was to use simple techniques and methods which yield the result in shorter time period, The case problems mainly deals with the production system optimisation in unit mines, areas/divisions and at the corporate levels. Also the management decisions regarding reorganisation of transport and distribution system of material and mineral are attempted to be optimised. Further, the case of management system development with computer aided decision making worked out for single large Iron Ore Project captive to a steel plant is outlined. Finally, the case of a large mining company having decentralised units and divisions geographically dispersed throughout the country, computerised management decision-information system designed on the basis of inputs and outputs of decision models relevant for different levels of management in the organisation is depicted.

Jan 1, 1986

By Edward Marszalek, Boleslaw Firganek

The paper deals with a computer method and algorithm of optimization of the rescue routes for the endangered staff in the case of fire in a given place of the mine. The adapted method is based on the objective function and realizes the algorithm of the shorest path with weighers assigned to it. The objective function is so defined that it reflects possibly all the hazards and difficulties arising during a fire in the mine. The algorithm is enhanced by an empirical formula for calculation of the smoke zone as result of a mine fire. The presented results of computations of optimal routes for several simple examples using the canonical scheme of the mine network and simulated fires are satisfying and prove the method, the algorithm and the coded program to be correct. The program will be a part of the software library of the mine ventilation engineer. The data for the program will be updated on-line from the fire detection systems.

Jan 1, 1989

By P. Chauvet

From a computational point of view calculating a variogram is a perfectly simple operation. For any particular study, we know which variable is to be studied. We also have a good idea of structural parameters which are likely to be important (the scale of the phenomenon, the probable direction of the anisotropy, etc.). Finally, we know the structure of the data file. So we can specify the parameters to be used to calculate the variogram (the distance classes, the angular classes, etc.). This allows us to decide which variogram program is most appropriate (1, 2 or 3 dimensional data, regularly or irregularly spaced, etc. ) . In general, the basic statistics (mean, variance, correlation? etc.) have been calculated beforehand, and so the distribution of the data is already known. Consequently, the choice of the parameter values fed into the variogram is by no means arbitrary. But it must nevertheless be made before the' variogram is calculated. If the resulting variogram is not satisfactory, the whole sequence of operations has to be repeated. Before going on to see how this can be avoided, it is worthwhile having a brief look at the common causes of "unsatisfactory" variograms.

Jan 1, 1982

By R. L. Grayson, S. Yuan

A stochastic model for evaluating the impact of the reliability and maintainability of shovels and trucks on the operational effectiveness of shovel-truck mining systems is presented. In the model, the Markov modeling technique is used to analyze the operating status of a shovel-truck mining system. Then, simulation is used to study the productivity of a shovel-truck system in a particular state. Finally, the relationship between the effectiveness of a shovel-truck system in terms of productivity and the reliability and maintainability of equipment is established. This relationship may be very useful to mine managers in making decisions in surface mining (e.g., regarding production process control, equipment replacement, and maintenance planning). A quantitative study is given to demonstrate how the reliability and maintainability of equipment affect the system effectiveness and how to pinpoint the parameter that has the most significant effect on the system effectiveness. The quantitative study indicated that in order to improve the system effectiveness significantly, the reliability and maintainability of the equipment need to be improved simultaneously.

Jan 1, 1995

By K. Cothern, S. Novack, D. A. Johnson, R. Borden, S. Pavlou

A procedure is presented for ranking hazardous waste sites for remedial decisions, and an example with application to mining waste sites is discussed. Typical contaminant concentrations are calculated from field data. Exposure indices that compare these measured concentrations with allowable limits are then computed. The limits are selected to protect both the health of humans (for both carcinogen and noncarcinogen effects) and the health of key organisms in the ecological food web. The additive exposure index for a site, defined as the sum of all contaminant-specific exposure indices, is then used in ranking the sites and assigning each a priority for remedial action. One key source of uncertainty in the process is the estimation of a typical site concentration from data that include values reported as "below certified reporting limit" (BCRL). This uncertainty is compounded in the additive exposure index and therefore may have a substantial effect on the assignment of remediation priority. A general approach is presented for incorporating consideration of BCRL data into uncertainty evaluation when assigning remediation priority designators to hazardous waste sites.

Jan 1, 1992

By R. Hemp

This paper describes work carried out to obtain a heat balance in the B3 shaft longwall stope at Blyvooruitzicht gold mine. Recordings were made of the temperature of the air and chilled water entering and leaving the section during three periods, August 1 September 1977, November 1 December 1977 and March 1978. These recordings, together with numerous other measurements were used to determine the rate at which heat was being removed from the section by the various fluids flowing through the section. The rate at which heat was entering the section was then calculated, by considering each source in turn. These two sets of figures made it possible to draw up a heat balance, and also obviously gave vital information on the magnitudes of the various heat sources and on the methods used to remove heat. In general reasonable heat balances were obtained, the errors being in the range -6 per cent to +22 per cent.

Jan 1, 1980

By G. France

The Blair Athol Coal Mine (BAC) is a large open cut operation in the Bowen Basin of Queensland, Australia. Current mine capacity is about 11 million tonnes per annum (Mtpa) of export coal. On-line analysis at BAC consists of two Coalscan 9500s installed directly on the output of the crusher plant and immediately before the product stockpiles, while a third Coalscan 9500 is installed on the transfer conveyor feeding the train loading bin. The two product Coals cans have a dual purpose. The first is to provide real time coal quality data directly back to the mining operations. The second is that of modeling the product stockpile with accurate on-line information. This modeling enables both production and coal quality personnel to accurately examine the coal quality of each stockpile with a degree of resolution which previously had never been achieved.

Jan 1, 1999

By John L. Stauffer, Allan Lipton, Kim Leitzel, Lesley Gaydos, Laurence M. Demers, Douglas C. Kuhn

Eicosanoids and cytokines produced by the alveolar macrophage (AM) are key mediators of pulmonary inflammation and fibrosis resulting from occupational exposure to mineral dust. In order to determine if eicosanoid and cytokine production are altered by chronic inhalation of coal dust, we compared the production of prostaglandin E2 (PGE2), thromboxane A2 (TxA2), leukotriene B4 (LTB4), interleukin 1 (IL-1), tumor necrosis factor (TNF) and platelet-derived growth factor (PDGF) by cultured AM from non-smoking normal human volunteers and coal miners. Inhibitors of eicosanoid biosynthesis were administered to AM from coal miners in order to determine if a link between eicosanoid and cytokine production exists in these cells. Basal PGE2, TxA2, TNF and IL-1 production by AM from active miners was increased compared to AM from normal volunteers. However, the production of these eicosanoids and cytokines by AM from former coal miners was reduced compared to control AM. Administration of the cyclooxygenase inhibitor, suprofen, and the lipoxygenase inhibitor, nordihydroguaiaretic acid, reduced PGE2 and TxA2 production in miners' AM but had no effect on LTB4, IL-1 or PDGF production. Specific inhibition of thromboxane synthase by UK38,485 was associated with a significant reduction in TNF production in active miners' AM but had no effect on PGE2, LTB4 or IL-1 production. The prostacyclin analogue ZK96,480 also specifically inhibited TxA2 production in active miners' AM. The results of these studies suggest that coal dust exposure is associated with alterations in AM eicosanoid and cytokine production which may be relevant to the development of pulmonary inflammation and fibrosis. In addition, the lack of effect of inhibitors of PGE2 biosynthesis on IL1 production in miners' AM suggests the production of these intercellular messengers may not be linked in AM chronically exposed to coal dust.

Jan 1, 1991

1. Theory of Wet Dust Suppression Techniques Wet dust suppression is the utilization of a liquid for the control, reduction or elimination of airborne dust, or the suppression of such dust at its source. Effective control involves: a. The confinement of the dust within the dust producing area by a curtain of moisture. b. The wetting of the dust by direct contact between the particles and droplets of moisture. c. The formation of agglomerates too heavy to remain airborne, by combining small dust particles with each other and with the droplets of liquid. From the standpoint of economy, availability and safety, water is the ideal fluid. From the standpoint of effectiveness, however, it leaves much to be desired. As a result, a tech¬nique has been devised in which very small percentages of specially formulated dust control compounds are blended with water to greatly enhance its dust suppression qualities. The terms "dust control compounds, wetting agents and surface active agents" are frequently used interchangeably. Although dust control compounds represent a specific type of wetting agent, a great many wetting agents are far from satisfactory for dust control. "Wetting Agents" is a broad category which covers such items as emulsifiers, solubilizers, detergents, foamers, penetrants, thickeners, etc. Dust control compounds, on the other hand, are carefully formulated blends in which one or more special surface active agents have been incorporated.

Jan 1, 1972

By Don Morris

The Building Products Company is Phoenix based and owned by Mission Clay products of California. Building Products is the only manufacturer of vitrified clay pipe in Arizona. The marketing area includes Arizona, Nevada, Utah, New Mexico, and California. Building Products, promoted by Arizona Public Service, was formed in 1970. Raw-materials prospecting was undertaken for 2 years, after which a $5-million plant was built. Initially, a satisfactory vitrified product could not be made with the raw materials then in hand. Subsequent prospecting and testing led to an acceptable raw-materials mix. Testing to upgrade the final product is a continuing process. The basic raw-materials supply must be adequate, secure, and capable of sustaining close tolerances in the final product. These needs are met by mining four geologic materials at three different localities: (1) refractory aluminous shales (two horizons-one pit) Colorado Plateau Province (Mogollon Rim); (2) less refractory aluminous materials from late Cenozoic lacustrine materials near Dewey in the Transition Zone (TZ); and (3) Precam¬brian "slate" from near New River along the southern edge of the TZ. Other additives include grog (ground-up, broken pipe) and barium carbonate that ties up what gypsum there is. Calcium magnesium carbonates are deleterious components that are minimized by careful selection of the mined products. The raw materials are blended and mixed, ground to 12 mesh, mixed in a pug mill, depleted of air, extruded into pipe ranging from 6 inches to 42 inches in diameter, transported to a hot-air drying room, fork-lifted to an appropriate kiln, and fired at a 1900-2000° F range. The "Rim" kaolinitic shales, being the most refractory ingredient, stabilize the pipe during the firing process. They are very plastic, and therefore facilitate extrusion. The Dewey clay fuses at a low temperature and forms an impervious glasslike binder. It also is plastic. The "slate" forms platy particles that tend to orient themselves during laminar flow. This provides strength for both the green and dried product. It doesn't absorb water, which helps the drying process. Grog remains stable during firing, and therefore helps to control shrinkage. The development of appropriate raw materials and proper mixtures has been done empirically.

Jan 1, 1987

By R. Sharma, S. Svoronos, S. Gupta, N. A. Abdel-Khalek

This paper presents the results of a column flotation study on a fine feed sample of Florida phosphate. A central composite design was used to study the main and interaction effects of parameters affecting column efficiency. The statistical design is also used to determine the optimum conditions. The results indicate that, depending on the experimental conditions, it is possible to produce a high-grade concentrate with a high recovery. A 15ppm concentration of nonionic frother was found sufficient to maximize the recovery at pH of 9.5.

Jan 1, 2002

By Henry G. Healy

Observation well (Hydrographs are shown for these selected wells) Contour represents the height, in feet referred to mean sea level, to which water would have risen in tightly cased wells that penetrate the major water- bearing formations in the Floridan aquifer, July 6-17, 1961. Contour interval 10 and 20 feet, changing at mean sea level. [ ] Extent and distribution of flow areas vary with fluctuations of the piezometric surface, particularly in areas of heavy Relatively small areas of artesian flow are not included immediately adjacent to and paralleling the coast and many of the major rivers and springs

Jan 1, 1966

By S. Komar Kawatra, Henry J. Walqui, Timothy C. Eisele

Population balance models were used to model the grinding action of industrial scale coal pulverizers. Experimental work was conducted with two different coal samples to determine the values of the appearance and selection function. These functions were determined for vertical mills by using s 6-inch by 10-inch laboratory roll mill to represent the action of a vertical mill. Two very important operating variables were identified for vertical mills: feed rate and roll spacing. Factorially designed experiments were used to analyze .and quantify the effect of these two variables. The models were then adapted to represent changes in operating conditions by incorporating the effect of the feed rate and roll spacing effects. This resulted in a simulation model able to respond to changes in operating conditions, by providing corrected predicted values for the product size distribution.

Jan 1, 2002

By Thomas Fiest, Helmut Wannenmacher, Wulf Schubert, Manuel Entfellner

Mining and tunneling in so-called “squeezing ground conditions” at high in-situ stress can result in substantial and enduring ground deformations. The magnitude of deformations is closely tied to the applied excavation- and support concept, though typically, they can reach tens of centimeters. The yielding principle is based on the idea, that the need for support capacity decreases as deformation increases. To enable controlled ground deformation and safe working conditions, yielding elements as a part of the shotcrete lining are implemented. These types of elements avoid an overstressing of the shotcrete lining. During the deformation process, the support pressure of the yielding elements and lining increases, thus stabilizing the ground. Furthermore, long-term creep deformations of the rock mass can be absorbed with such a system. This economic support technique represents the state-of-the-art infrastructure tunneling practice in squeezing ground condition. A novel yielding element of High-Strength Expanded Polystyrene (HS-EPS) was invented, which overcomes existing systems’ drawbacks. This innovative system is lightweight and allows for safe and rapid installation. Furthermore, the modular setup of the element enables an easy on-site adaption to react to in-situ deformation patterns and changing ground conditions. Recent experiences from applications in Alpine base tunnels in squeezing ground are presented.

Jun 25, 2024