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By Ted H. Eyde

Specialty sand and bentonite are produced in the plateau province from the Bidahochi Formation near Sanders, Apache County, Arizona. It appears that deposits of both sand and bentonite formed during the Pliocene in fluvial and lacustrine environments, respectively, along the west side of the Defiance Uplift. The bentonite is an alteration product of airborne vitric ash that fell or was washed into lakes. In the Cheto district, the individual bentonite horizons, which range from less than a foot to more than 10 feet thick, are restricted to the position of the medial volcanic member. Bentonite production began at the Allentown mine in 1924 and the Chambers mine in 1926. In 1933 strip mining of the extensive deposits in the Cheto district commenced. Production increased each year to a peak of 270,000 tons in 1957. As a result of the introduction of synthetic zeolites into petroleum refining, production declined. About 40,000 tons of bentonite are currently produced from the district each year. Bentonite is shipped out of State for processing into desiccants, thickeners, and acid-activated clay products. The specialty sand was derived from Permian sandstones and deposited by streams draining the Defiance Uplift. Although stream channels are usually restricted to the upper member of the Bidahochi, stratigraphically above the bentonite horizon, a few actually cut through the bentonite. The well-sorted sand, suitable for use as a proppant in hydraulically fractured oil and gas wells, is localized in elongate lenses along the margins of the channels. These lenses range from 5 to 50 feet in thickness and often extend thousands of feet in both width and length. The sand is about 97 percent silica, has a yield of 40 percent in the minus 20 plus 40 mesh size fraction, and has a roundness of 0.6 to 0.7 on the Krumbein scale. Production of this sand began about 1961. All of the current production, which amounts to about 40,000 tons per year, is sold in the petroleum-producing area near Farmington, New Mexico.

Jan 1, 1987

By L. Alagha, O. Molatlhegi, S. Khatibi

"In the present study, the effect of organic/inorganic (hybrid) polyacrylamide polymer on fine coal flotation was investigated. Raw coal samples contain about 37% of ash-forming mineral at a feed size of -75 + 38 um were subjected to flotation tests in the presence of in-house synthesized hybrid Al(OH)3-PAM at different polymer dosages and pH values. Results show a significant improvement in both combustible recovery and ash rejection at 1 ppm polymer dosage. Further improvement of combustible recovery was obtained when flotation was performed at pH 5. Interfacial properties of coal particles before and after flotation were examined through electrokinetic (zeta potential) measurements of coal/water slurries. Zeta potential vs. pH curve were established and compared. In the case of raw coal/water slurry, zeta potential-pH curve resembles the ash-forming minerals (silica and clays) more than coal. After Al(OH)3-PAM-assisted flotation, the zeta potential of froth/water slurry shifted to more positive values point which strongly indicates significant removal of ash-forming minerals from coal by Al(OH)3-PAM. INTRODUCTION Coal has been a major commodity in meeting the world energy demand during the past several decades (Milici et al., 2013). According to the international energy agency, global coal demand will continue to increase for the coming decades. With increasing world population, the global electricity demand would also increase as more people would get access to basic electricity especially in developing countries (Maggio & Cacciola, 2012). Due to this increase in energy consumption, operations in coal mining and beneficiation processes have been highly mechanized to meet the demands. This mechanization has increased the quantity of raw fine coal particles produced which contain high amount of ash-forming mineral matter (slimes). Aplan et al., have reported that the major constituents of ash-forming minerals in U.S.A coal are clay minerals such as kaolinite, montmorillonite and illite (Aplan, 1997). Conventional froth flotation for fine coal cleaning suffers mainly from two major problems: 1) Low recovery of ultrafine coal particles due to slime coating by ash-forming minerals, and 2) The lack of selectivity, which results in the flotation of middlings and entrainment of mineral fines in the froth (Polat et al., 2003). Slime coating on both valuable and air bubbles have been proposed to explain the observed reduction in flotation recovery especially when fine grinding is required. In this case mineral matter may be degraded to extremely fine or colloidal sizes thereby creating difficulty in the water clarification process such as flotation. Slimes inhibit bubble-particle attachment, and increases reagent consumption due to the increase in solid/liquid interfacial area, resulting in low coal recovery."

Jan 1, 2015

By Arthur F. Eidson

INTRODUCTION If a uranium mill worker is involved in an accident, analysis of excreta for uranium content and[in vivo] counting methods are used to estimate the extent of the possible exposure and to predict the pattern of uranium distribution among tissues (Spitz, [et al]., 1980). Interpretations of urinary excretion data are based on studies of human exposures to single uranium compounds including U02, U308, U03, UF4, U02F2 and UF6 (Alexander, 1974). Refined uranium ore (yellowcake) is a variable mixture of U03-NH3-H20 adducts (ammonium diuranate, ADU) and their thermal conversion product, U308. The variability in composition of yellowcake (Kalkwarf, 1979; Eidson and Mewhinney, 1980; Dennis, Blauer and Kent, 1981) complicates the interpretation of bioassay data from individuals that might have inhaled any single yellowcake material. A test system would be useful to estimate the dissolution behavior of a particular yellowcake aerosol inhaled by a worker and aid in the interpretation of bioassay data collected before and after an accident. A series of experiments was conducted for this purpose. The objectives of these studies were to: 1) develop specific criteria for comparing [in vitro] dissolution systems and 2) use the criteria to evaluate solvents, methods and experimental temperature and pH conditions used in previous studies. Dissolution experiments were conducted using different combinations of solvents, conditions and methods with a common yellowcake sample. Because little information is available from human yellowcake inhalation exposures to evaluate the [in vitro] results, criteria for evaluation of different tests were derived from a model of yellowcake dissolution in lung constructed from a number of cases in which humans were exposed to single uranium compounds known to be in yellowcake (Mercer, 1975). MATERIALS AND METHODS Materials The powder used in the tests was taken from one lot of yellowcake obtained from a commercial uranium mill. The same powder was previously designated as Mill D in Eidson and Mewhinney, 1980 and Mill 2 in Kalkwarf, 1979. The ammonium diuranate content was measured by infrared absorption to be 25% ± 1% (Eidson and Mewhinney, 1980). Solvents The compositions of the two biological fluid simulants used are compared in Table 1. Simulated lung fluid (SLF) (Kalkwarf, 1979; Dennis, Blauer and Kent, 1981) was chosen to simulate the composition [ ] of lung fluid as closely as practical (Moss, 1979). Simulated blood serum ultrafiltrate (SUF) (Eidson and Mewhinney, 1980) was chosen because of previous successful efforts to model human urinary excretion of inhaled plutonium aerosols (Kanapilly Raabe and Boyd, 1974) and the dissolution rate of 241Am02 in Beagle dogs (Mewhinney and Griffith, 1981). Major differences are that simulated lung fluid contains Mg2+ and a higher Ca2+ concentration than SUF and that SUF contains ammonium ion. Both solvents include protein substitutes; acetate is used in SLF, while amino acids are used in SUF. Both solvents include phosphate but the chelating agent diethylenetriaminepentaacetic acid (DTPA) is included in SUF to prevent possible formation of insoluble uranyl phosphate precipitates that would result in an underestimation of solubility. In addition to the above solvents, modified solvent compositions were prepared to investigate the role of specific salts in yellowcake dissolution studies. Solutions of SUF (Table 1) were prepared without DTPA (SUF-DTPA) and without amino acids (SUF-amino acids). No solution excluded both DTPA and amino acids. The SLF solutions were prepared with DTPA (SLF + DTPA) and without phosphate

Jan 1, 1981

By K. F. Unrug

The research work reported in in this paper deals with the monitoring of roof behavior in a drift mine located in Eastern Kentucky operating in the Coalburg Seam. The thickness of the seam at the monitoring site ranges between 9 and 10 feet with the immediate roof changing from sandstone to shale then back to sandstone. Shale thickness varies between 0 and 2.5 feet. The characteristics of the immediate shaly roof were monitored with 38 dynamometers which were set up in three survey lines to cover the entire range of shale distribution. The dynamometers are capable of providing accurate load readings in the range of +/- 5 pounds. To closely observe the contribution of moisture toward roof deterioration the dynamometers were set up in intake and neutral airways. A television borescoping camera was used in conjunction with the dynamo- metric instrumentations at pre- determined observation holes to physically observe and record the separation process of the shale and sandstone stratum with respect to time. Monitoring took place between January 1985 through January 1986 in order to cover a full cycle of dry and wet mine conditions associated with the seasonal changes. Analysis of the data show a trend of roof deterioration induced by condensation and eventual penetration of moisture within the immediate roof bedding planes, leading to rapid disintegration of the mine roof.

Jan 1, 1986

By P. D. Lafleur

A concerted effort to determine the quantities and effects of trace elements in the environment requires the application of a number of different analytical techniques in the same or in different laboratories. The interpretation of analytical data is often difficult because of differing results between analysts or even by the same analyst at different times. Standard Reference Materials (SRM), which are certified for their trace element content and are in a matrix similar to the one of interest, can greatly increase the accuracy of analysis and the reproducibility between laboratories. The United States National Bureau of Standards (NBS) has developed a number of SRMs applicable to the determination of trace elements in environmental materials. Two of these, SRM-1571, Orchard Leaves, and SRM-1577. Bovine Liver, are excellent for biological tissue analyses. Several new standards are of value for fossil-fuel analyses. These are: SRM-1632. Trace Elements in Coal; SM-1633, Trace Elements in Fly Ash; SM-1634, Trace Elements in Residual Fuel Oil: and SRM-1635, Trace Elements in Gasoline. In cooperation with the US Environmental Protection Agency, the NBS has recently concluded an interlaboratory comparison involving analyses by more than 60 laboratories on these fossil-fuel materials. The resulu of this intercomparison and the broad range experience with the biological materials will be presented showing both intratechnique and intertechnique variations, and the sensitivities and comparisons with the values certified by NBS.

Jan 1, 1975

By Pentti Kallio

From the aspect of economic feasibility of mining, ineffective use of expensive mechanization investments is becoming a problem. In many cases, the machinery is in operation only 50 - 60 % of the total working time. The lost time when the machines are idle means a considerable over-investment in machines. The lost time, with LHD equipment in particular, accumulates from the following constituents: - the needs of the person operating the machine trips to the work site, lunch, coffee and other breaks, want for comfort, etc. - deficiencies in the monitoring and control systems for machine operation waiting periods at loading and unloading stations, unnecessary and erroneous actions, inefficient work, etc. - deficiencies in the machine condition monitoring system , and inefficient service and maintenance work The data transfer and computer technology of today provides means for resolving problems in several areas - including the area of underground loading operations. In the paper those areas of automation and data handling are considered which make possible an improvement in the usage and monitoring of LHD equipment. These fields are: remote control of equipment, use of TV cameras and monitors in remote control, locating equipment and data transfer down the mine, measurement of the load and the data storing system, systems for following the condition of the equipment, unmanned operation of equipment.

Jan 1, 1989

By Karl H. Bruemmer

1. TRENDS OF DEVELOPMENT IN THE MECHANICAL DRIVING OF UNDERGROUND EXCAVATIONS IN THE GERMAN COAL MINING INDUSTRY The demand for higher advance in underground excavations led, in the past ten years, to the development and application of various mechanical methods in the coal mining industry of the Federal Republic of Germany. Hence, a modern mine cannot operate anymore without tunneling machines for the driving of horizontal and inclined roads and shaft boring machines for the sinking of shafts. In future, boring operations will assume a high positional value in the mining industry, as the development of cutters has kept pace with the development of machines. In the past ten years, about 40 km of roadways have been bored by tunneling machines in the German coal mining industry, further 140 km will be bored by 1990, part of which are already under contract. The idea was tempting to apply the technology of horizontal tunnel borers also to the sinking of vertical shafts. The underground contractors Deilmann-Haniel GmbH of Dortmund and Thyssen Schachtbau GmbH of Mülheim/Ruhr developed already in 1970, together with Wirth of Erkelenz, a shaft boring machine working without drill pipes, capable of sinking shafts following a pilot borehole, according to the downward reaming method (Fig. 1). In the meantime, two such shaft borers are operating in coal mines with diameters of 4.50 m to 6.50 m. Recently an order was placed for a third Wirth shaft borer for diameters up to 8.50 m. Since 1971 about 3.800 m of open or blind shafts have been sunk by the reaming process (Fig. 2).

Jan 1, 1979

By Prasad S. Mulukutla

INTRODUCTION The use of specialty chemicals In mining Is an Important consideration In determining the economic efficiency of a floatation plant. The plant metallurgist would like to maximize the recovery of valuable minerals while maintaining an acceptable grade product. The direct cost of the reagents, while significant, Is only a part of their economic effect. Reagents determine the flotation rates and the selectivity of the mineral separation. In flotation practice, mineral selectivity can be achieved through the addition of various reagents that can control the wettablllty of a particular mineral In the flotation pulp. The reagents which will generally optimize the flotation process are commonly classified Into three distinctive categories: collectors frothers and modifiers. Large tonnages of metal sulphide concentrates which are the source of most of the common base metals are produced economically by fairly standard flotation techniques. The advent of modern technology coupled with the necessity of processing finely disseminated and complex ores of low grade has Increased the need for utilization of non traditional and high selective chemicals reagents for the economic recovery of metals and raw materials. Mining operations in developing countries continue to progress at a rapid growth as many countries mine and process both metallic and nonmetallic ores. The total mine production of base metals, precious metals, Iron ores and coal In developing countries In Africa, Asia and South America has been much higher as compared to the western world production In terms of tonnage and dollar value. Global capital Investments In mining during 1991-95 Is $ 55.1 billion and It Is anticipated that the development of new and specialty reagents may be concentrated In the processing of aluminum , copper, precious metals and Industrial minerals with special reference to potash, phosphates, kaolin and silica sands.(1) The challenge for the design and development of new specialty chemicals Is dependent on Its cost performance and environmental acceptability. Information on the theory and application on the development of mining chemicals has been reviewed In several conference proceedlngs,(2-4) publications(5) and also discussed by several Individual authors.(1,6-10) These publications serve as a comprehensive reference source on the reagents used In several flotation processes. This paper discusses the present trend in the use of specialty mining chemicals In diversified mining operations on several mineral systems with particular reference to sulfide ore systems. The necessity to expose these specialty chemicals through aggressive marketing techniques In mining operations In many developing countries Is also presented. SPECIALTY CHEMICALS Specialty mining chemicals, like other specialty chemicals, share common business characteristics that transcend geographic boundaries. They are manufactured 1n a few selected areas, generally expensive relative to commodity chemicals, shipped and compete globally and usually require specialized knowledge for proper use. Specialty mining chemicals are relative newcomers to chemical markets. The vast majority of mining chemicals are derived from products that are less than two decades old. Traditional collectors and frothers have been available for a considerably longer time. The emphasis on adding value to existing products and byproducts Is responsible for several characteristic features of the mining chemicals business. Most raw materials for these chemicals are related to oil and gas byproducts, chemical refineries, pulp and paper mills and all chemical manufacturers. Until the last several years these operations were located In Industrialized countries, while a significant number of mining chemical users were In developing countries. Therefore International trade In mining chemicals developed through agencies or agents in each particular country.

Jan 1, 1993

By D. Murray

"The Mine Improvement and New Emergency Response (MINER) Act included the need for improved chemical technologies to address respiratory protective device inadequacies and refuge alternative development. The National Institute for Occupational Safety and Health’s (NIOSH) National Personal Protective Technology Laboratory (NPPTL) invests in research and development to improve the carbon dioxide (CO2) scrubbing technologies built into these mine safety systems. Testing at NIOSH NPPTL is performed using a custom-designed test system containing a chemical reactor and sensors in a constant flow of simulated expired breath to evaluate chemical performance for the scrubber materials. Current testing procedures focus on device duration or capacity, but do not report criteria needed to effectively optimize chemical performance. In this presentation, testing results which identify the chemical performance roles for CO2 scrubber components will be reported, and specific component chemical activities will be linked to both duration and CO2 absorption capacities. Chemical components being evaluated include hydroxyl, superoxides, metal, and amine active sites, distributed in salts, zeolites, metal-organic frameworks, and microporous materials. INTRODUCTION CO2 absorbents and oxygen sources are at the heart of closed circuit breathing air supply systems used in mining escape and rescue operations. CO2 absorbent technology was first developed for diving rebreathers and has been in use for over a century. Typically these devices include a soda lime formulation of pellets in the 8-12 mesh range. Larger 4-8 mesh particles are used in medical grade “low-flow” applications, since these particles present a lower flow resistance regime more amenable for use with resting individuals. Potassium superoxide and lithium hydroxide formulations are also used, where in each case the formulations involve bulk solid pellets or materials affixed to surfaces. CO2 capture technologies are now under intensive study in the energy and automotive industries, where the pursuit of optimal combustion processes has led to the development of new materials to capture, convert and store CO2, oxygen and carbon monoxide gases. Recent advances in nano-structured and high surface area catalysis have produced novel materials demonstrating chemical performance improvements in these industries, and these improvements may now also be adapted to enhance chemical efficiency and performance in escape and rescue devices. Higher surface area materials offer promise for improving the efficiency, or decreasing the burdens associated with the use of closed circuit respiratory protective devices containing CO2 absorbents. Novel chemicals that display advantages in chemical performance or decreased burden will be examined for inclusion in developing systems such as the next-generation closed-circuit mining escape respirator or refuge alternatives."

Jan 1, 2018

By Ellis Brien, O&apos

The fine coal fraction of a coal stream is that fraction which contains particles essentially in the -28 mesh size range. This fraction will normally first appear, in a coal preparation process, as a result of classification to segregate raw coal into various size components for beneficiation. More specifically, it could appear in desliming screen underfiow, classifying cyclone overflow, and in other process circuit components. It's recognized that the top size of this fraction has been determined more by secondary reasons, such as desliming screen area for the heavy medium cyclone circuit, the dewatering equipment for the fine clean coal, or even the stability of the refuse thickener circuit. Benefits, both economic and environmental, gained by beneficiating the fine coal fraction of a raw coal stream are increasing in number, until today, fine coal beneficiation is a necessity in most coal operations requiring any degree of preparation. This is due to some of the following reasons: • In the past it was frequently more economical to discard -28 mesh raw coal sizes than to recover the coal values from them. Today, mining costs have escalated to the point where all coal values leaving the mine should report to the finished product if possible. • Today's mining methods are producing run-of-mine coals containing higher percentages of -28 mesh sizes. This heavily weighs the economic balance in favor of beneficiating this fraction. As much as 25% of the run-of-mine coal from some mines is in the fine coal fraction. Beneficiation is recommended so that clean coal contained in the fraction can be recovered to reduce the loss of coal values. • Existing and pending environmental regulations mandate that solid fuels now consumed in power station boilers contain almost no pyritic sulfur. This form of sulfur appears in raw coal in the fine coal fraction, but can be removed by coal beneficiation. Environmental considerations dictate that every year, more of the fine coal produced for steam generating purposes in the US be beneficiated. To deliberately discard any portion of the fine coal can only add to this cost, not only in the sense that fewer tons will be recovered but, more importantly, additional tonnage will be diverted to the most capital- and labor-intensive section of the entire preparation plant-the fine refuse dewatering section. It is apparent to preparation engineers that dewatering and ultimate disposal of the fine refuse derived from this beneficiation step is certainly the most difficult technical problem presented in the entire plant design. Therefore, any beneficiation procedure which increases the fine coal recovery, or in any manner decreases the tonnage of fine refuse to be dewatered, is going to be cost effective. Since the -28 mesh fraction contains both coal and refuse particles in their finest particle sizes and thus presents the greatest degree of liberation, one would immediately infer that the highest degree of beneficiation would be achieved. This is not the case-the opposite is more likely true. Conventional coal cleaning devices based on specific gravity (such as

Jan 8, 1980

By George Mandarakas, Johan van Zyl, Karl-Heinz Becker

The world’s climate today has changed compared to 10 or 20 years ago. Many countries face water shortages; water sourcing for mining activities has become harder to secure. ESG’s focus on the industry has made us more aware of the need to preserve and responsibly use the water needed for wet processing in our milling and sorting activities. In a recent greenfield project in South Australia, 10 Gigalitres per annum would be required to process 5Mtpa of magnetite [1]. Published information indicates that the mining industry consumes approximately 12 EJ per year—or 3.5% of total global final energy consumption globally [2] or 3.33 trillion kilowatt hrs. This energy consumption is significant, considering the critical role mining plays in extracting and processing essential minerals for economic development and human progress. The perception of the mining industry is that not only does it consume significant power, but it also consumes a lot of the freshwater in the world. In fact, it consumes approximately 5% [3] of the total freshwater demand. According to the Intergovernmental Panel on Climate Change (IPCC), by 2050, 60% of the world’s population will be living in countries that are classed as water-stressed [3]. As more and more emphasis is placed on renewable energy sources, the amount of water used in mineral processing will increase because more and more raw materials require a water-intensive process. This increases the pressure on the mining industry to try and find water-saving initiatives. As part of this review, recent advancements in magnets have enabled magnetite processing facilities to achieve between 30 to 40% dry gangue material rejection before the wet beneficiation process (grinding and sorting). This reduction in energy consumption allows the reduction of energy consumption. Secondly, there is less material ground in the mills, which requires less water for mineral downstream processing.

Feb 1, 2025

By B. C. Haimson

The Committee on Rapid Excavation of the National Research Council has recognized in its 1968 report the need for "improvement of rock-mechanics techniques for measuring subsurface stress field in deep boreholes and for determining stress distribution in walls of underground excavations". The technique recommended in this paper as being most suitable for both deep hole and tunnel wall stress determination is Hydraulic Fracturing. Using this method stresses are calculated directly from the fluid pressures necessary to initiate and extend a fracture away from a borehole. Stress determination by hydraulic fracturing is rather insensitive to inhomogeneity or anisotropy, is not limited in depth except by the length of the hole, requires simple equipment which is commercially available, and can be carried out by unskilled personnel. The method has been worked out theoretically and extensively tested and verified in the laboratory. A number of field tests in deep holes ranging from 300 to 6300 ft have yielded surprisingly good results. Preliminary underground tests have been very encouraging and most recent measurements in a tunnel complex at the Nevada Test Site yielded stresses that were both consistent and reasonable when compared with the expected directionsand magnitudes. It is recommended that hydraulic fracturing be considered as a method of in-situ stress measurement both in the pre-excavation stage of design and during tunneling.

Jan 1, 1974

By William J. Francart, Edward J. Miller

The utilization of computer based monitoring systems for fire detection in underground coal mines has grown significantly in the past seven years. In 1984, an annual MSHA survey identified a total of 38 systems being used in U.S. underground coal mines, while a 1990 survey indicated the number has risen to 112. The applications for mine monitoring have also changed according to the annual surveys. From April 24 to June 21, 1990, investigations were conducted by personnel of the Ventilation Division, Pittsburgh Health Technology Center, in cooperation with Coal Mine Safety and Health, concerning the installation and operation of Atmospheric Monitoring Systems in underground coal mines. These investigations were conducted to gather information concerning the ability of the AMS to detect fires and heatings, false and nuisance alarm frequencies, information related to system maintenance, and information related to employee training on system operations. This paper addresses current applications of the systems, fire and heating identification rates, application of systems in dieselized coal mines, system maintenance, and employee training requirements. While deficiencies were identified in some applications, results of the studies and survey indicate the use of atmospheric monitoring systems can be effective in identifying mine fires and heatings.

Jan 1, 1991

By E. Topuz, Xing Wu

INTRODUCTION The air flow in the mine ventilation network can be categorized in three ways: natural splitting, controlled splitting, and semi-controlled splitting. In natural splitting, the air flow in branches of a ventilation network apportions itself according to the aerodynamic resistance of the branches. In controlled splitting, a prescribed quantity of air is circulated through each branch. In semi-controlled splitting, flow in some branches is fixed to a desired quantity while in other branches it is split naturally. In practice, the mine ventilation networks present the latter two situations. Usually, the resistance of each branch in the network is known and the quantity of air in the working place is predetermined by safety considerations. If the number of branches whose airflow quantities are known is equal to or larger than the number of the fundamental meshes in the network, then the network becomes a controlled splitting network (Wang, 1982 a). Otherwise, it is a semi-controlled splitting network. If no booster fans are used in the network, the problem can be solved as either controlled or semi-controlled splitting networks in order to determine the main fan pressure and regulator size and location. All techniques are based on Kirchoff's flow and energy conservation laws and Atkinson's Equation. Booster fans can be used in controlled and semi-controlled splitting networks. It has been proven both theoretically and practically that using booster fans in these ventilation systems can improve flow distribution and reduce consumption of power (McPherson et al., 1985). The current techniques used in determination of booster fan location and size include simulation, linear programming, CPM and cutset operation, out-of-kilter, and critical-path crashing. These techniques can be classified into two groups. The first group, including linear programming, CPM and cutset operation, out-of-kilter, and critical-path crashing techniques, deals with controlled flow networks. The second, simulation, can be applied to the handling of semi-controlled flow networks. Mathematically, the problem of controlled splitting networks can be solved more easily than that of semi-controlled splitting networks. This is because the controlled flow network can be formulated as a linear programming problem, for the solution of which there are several sophisticated algorithms. Moreover, the semi-controlled flow network is usually modeled through nonlinear programming, for which there are no universally applicable solutions. The procedure described by Wu and Topuz, 1986, can be used to convert a semi-controlled network to a controlled flow network, and the problem can then be easily solved by the techniques used for solution of a controlled flow network problem. In practice, a mine ventilation network may change from controlled splitting to semicontrolled splitting with advancement of mining. This dynamic nature of mine ventilation makes the problem more complicated and necessitates development of new solution procedures which will consider the overall economics of the system. CONTROLLED SPLITTING NETWORK The problem in controlled splitting networks with booster fans is to determine the operational characteristic of the main fans, and the location and size of booster fans and regulators. The objective is to satisfy the air flow rate requirement for each branch while minimizing consumption of energy. The techniques used for the controlled splitting network problem include linear programming, CPM and cutset operation, out-of-kilter, and critical-path crashing. The objective function and constraints can be expressed as follows (Wang and Pana, 1971): [ ]

Jan 1, 1989

By R. J. Watters

Many rock sass classification systems exist' to assist the engineer in assessing the rock support requirements for underground design. Our ongoing research in this area is directed at attempting to utilize the fractal dimension and the acoustic emission' response of the tuffs at Yucca Mountain, Nevada to further aid in rock mass classification. The Topopah Spring' member, the proposed nuclear waste horizon, is characterized by welded and partly welded tuffs, exhibiting a wide range in moduli, strength, porosity and degree of fracturing. Differentiating between the different' types of porosity can be extremely difficult if not impossible. An attempt was made to correlate the acoustic emission response with the porosity of the sample. Events and the peak amplitude may offer a means-to distinguish between, fracture porosity and pore porosity. In addition-, fractal dimension were calculated for several fractures in densely welded tuffs. Two techniques for calculating fractal dimension were-applied' to describe-fracture geometry and roughness. Fractures in-welded-tuff were-found to be relatively smooth.

Jan 1, 1989

By Wang Xifu, Zhang Daxian, Zhang Youdi

In mine haulage system, the surge bunker or stockpile installed between two facilities can raise the system production capacity. The arrangement of surge bunker has great relation with the capability development of the whole haulage system and the economic benifit. In the haulage system, surge bunker plays a role of surge capacity, accident capacity and technology capacity. In this paper, the variation of the material in surge bunker is analysed while the mine haulage system is working, the calculation method of the whole output is raised. With the goal of the maximum system output, the method of deciding the rational size of surge bunker is put out. In case study, the system output in Huolinhe surface mine is calculated, thus the rational size of surge bunker in huaulage system is decided.

Jan 1, 1996

By E. Topuz, M. J. McPherson, I. M. Konduri

This paper describes experiments conducted to evaluate the effectiveness of jet fans for ventilating blind headings in under- ground mines. A laboratory model of a mine heading was built by using dynamic similarity criteria, and water as the fluid medium. In order to verify laboratory test results, field experiments were designed and carried out in a full scale mine model and in a coal mine in West Virginia. Using CO, as the tracer gas and in combination with a computerized gas monitoring system, tests were conducted to evaluate jet fan performance. The results highlight the flexibility and versatility of jet fans for ventilating blind headings. Numerical modeling of a jet fan in a typical coal mine heading was carried out to evaluate the potential of computational fluid dynamics.

Jan 1, 1997

By Tsutomu Yanagase

Non-ferrous smelting industry in Japan often had the severe problems about the over production of sulfuric acid. There has been such a closed relation between amount of sulfuric acid from non-ferrous smelting industry and the products of copper, zinc and lead metals that the production of one ton of copper accompanies three tons of H2S04. When the proper balance exists in both markets this situation certainly brings bigger profits. In Xining and Metallurgical Institute of Japan the research commitee concerned with the fixation process of sulfur in non-ferrous smelting industry was established in 1977 and continued the activity for four years untill 1981. This paper will introduce some of the activities involved in the report published by the committee.

Jan 1, 1982

By William J. Douglas

Critical path modeling (CPM) has been used widely as a tool to manage large-scale projects having many activities which are conducted in series or parallel. The construction industry is a regular user of critical path modeling as a planning tool. In this context, the method is used to provide an orderly schedule for all activities to forecast delays, slippages, and problem areas and to identify critical activities where resources should be directed. It also identifies others which have slack time, and provides information on the degrees of freedom and flexibility available in completing the project. The purpose of applying critical path modeling to an underground mining system is not primarily for scheduling, but as an analysis tool. In observing underground mining systems, it Is clear that repeated sequences of activities must take place for mining to proceed efficiently. Some of these activities must be sequential, while others be carried out in parallel. The fundamental difference between critical path modeling applied to mining versus a large-scale construction project are: (1) The activities in a mining system are cyclic in nature. (2) The location of the activity varies, and the entire process is not thought of as co-located, as is the case in a construction project. Another important aspect of the network development for mining systems is the degree of detail that is desired. One can be concerned with very macroscopic networks which represent, for example, an entire mine life cycle. Networks representing this problem would be more closely analogous to those of a large construction project. On the other hand, one might be interested in evaluating alternative ways of developing a property or of mining in a given section. More detailed networks representing the section activities are necessary to evaluate system parameters and their impact on long-term production.

Jan 1, 1978

By Felicia F. Peng

To minimize SO2 emission and the particulate problem during combustion of high sulfur coal fines is to agglomerate these fines in the presence of limestone. At subsequent combustion process, the sulfur in coal is oxidized and reacts with calcined limestone to form calcium sulfate in ash, while the base carbon is converted to clean energy. Seventy percent of sulfur retention can be achieved at Ca/S mole ratio of 3 at a temperature range of 500-400°C. The sulfur fixation in agglomerates involves the complex mass transfer and multiple successive reactions. The rate expressions have been developed to describe the progress of sulfur fixation in the agglomerates during combustion.

Jan 1, 1985