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By William E. Wallace, Michael J. Keane

This review summarizes three sets of ongoing studies which we are performing in collaboration with a number of researchers associated with the Dept. of Interior - Generic Mineral Technology Center for the Study of Respirable Dusts, concerning surfactant-particle interactions studied using this surrogate surfactant. These topics are: (A) the suppression of mineral particle cytotoxic potential by DPL adsorption and the persistence of this effect under conditions of enzymatic digestion; (B) surfactant suppression of organic particle cytotoxicity by DPL adsorption and the effect on subsequent expression of genotoxic potential; (C) potential effects of surfactant on heterogeneous structured complex respirable particles. The references list some of our reports which can provide additional information on these studies. Further, those reports provide references to the literature of the field and to the works of others on these topics. Deep lung airspaces, the pulmonary alveoli and respiratory bronchioles, are coated with a hypophase which is rich in surfactant biomolecules secreted by the alveolar type II epithelial cells. The surfactant is known to be critical to maintaining stable low surface tensions on the inner surfaces of the alveoli by forming a surfactant layer on the airliquid interface of the alveolar hypophase. Upon deposition in the acinar regions of the lung a respired particle's initial contact will be with this surfactant coating over pulmonary tissue. A primary component of this surfactant is the phospholipid diacyl glycerophosphorylcholine, commonly called lecithin. A surface layer of dipalmitoly lecithin on saline will act much as full pulmonary surfactant in decreasing surface tension and producing a hysteresis in surface tension behavior with surface area. We have used dipalmitoyl glycerophosphorylcholine, or dipalmitoyl lecithin (DPL), a major component of that surfactant, dispersed in physiologic saline as a surrogate for studying interactions of both mineral and organic respirable particles with pulmonary surfactant and consequent effects on particle toxic behavior. A. DUST CYTOTOXICITY AND LECITHIN SURFACTANT ADSORPTION Respirable quartz and kaolin clay particles are found to be comparably cytotoxic in a number of in vitro bioassays including lavaged rat pulmonary macrophage release of cytosolic and lysosomal enzymes, and red blood cell hemolysis as a measure of dust membranolytic potential. These direct and prompt cytotoxic activities do not account for the distinctly greater potential for quartz to induce pulmonary disease. When respirable quartz and kaolin are incubated with a dispersion of DPL in saline at 37C it is found that the prompt cytotoxicity of both dusts is fully suppressed as measured in vitro by pulmonary macrophage release of lactate dehydrogenase, beta-N-

Jan 1, 1991

Marble has been recognized as a valuable natural resource ever since ancient times. Due to its peculiar aesthetic and technical characteristics as well as the lithotype uniqueness, it has widely been appreciated over the past centuries. In present times its production and demand are enjoying an increasing trend, with comparatively high market prices. All this considered, marble can be included among these natural resources whose exploitation provided, and still provides, an important contribution to the growth of the economic system. Nevertheless, there is at least one more important reason that makes marble a valued resource. For ages, marble represented one of the most important raw materials for sculpture sand architectural masterpieces, which constitute part of the cultural heritage of mankind. With this in mind, the value of marble is strictly related to its extraordinary capability to preserve cultural heritage and therefore to convey civilization from past to future generations. In other words, the role of marble should be recognized as being of the utmost importance in order to attain an overall objective of ?cultural sustainability?, that is, the assurance of the inter-generational flow of the cultural heritage capital. To achieve this sustainability goal, the priorities should be to protect and preserve the world?s artistic and architectural historical heritage, which require restoration works. In this field, a very il task is entrusted to the extractive industry: this industry, in cooperation with historians, art experts and public authorities, is in charge of detecting and supplying historical stones for restoration purposes, taking into consideration that, in order to restore a monument in a correct way, the same lithotypes the monument was made from are needed. These marbles are often no longer in production, so that it becomes necessary to find the location of the original quarries, as only there is it possible to extract even the small quantities of stones that are needed. In this case, the stone, located in its geological context, could have such valued characteristics as to be considered an important public asset and consequently a resource to be preserved and protected even beyond the market conditions. This important task should be carried out by the public administration through a targeted intervention of territorial planning and monitoring, which could include the support for the specific extractive activity.

Jan 1, 2003

By L. Eros, R. H. King

The US Bureau of Mines has funded several research and development projects in computerized mine monitoring and control. Hardware and software components have been sufficiently developed so that mine operators have been provided with an efficient means to comply with federal regulations and increase mine safety. Several cost benefits have been realized as well, particularly with increased conveyor belt haulage availability. Western Fuels-Utah Inc. approached the Bureau to assist in planning, installing, and evaluating a computerized mine monitoring and control system because of the agency's research experience in this area. The installation was planned for Western Fuel's Deserado mine, located in Rangely, CO. Since a large, complex, underground mine producing about 2.4 Mt/a (2.7 million stpy) of coal was projected, the company anticipated significant benefits in safety and efficiency through a computerized monitoring and control system. A major part of the cooperative program was to document and evaluate the system design, installation, and operation. This will assist others to adequately design, specify, install, and operate future systems. Mine description The Deserado mine plan and layout have important impacts on the monitoring system requirements. Long range plans are to produce 2.4 Mt (2.7 million st) of clean coal annually from two longwall sections and four continuous sections. Presently, two continuous miner sections operate under 213 m (700 ft) of overburden in the 2.3 to 2.5 m (7.5 to 8.5 ft) thick D seam to develop main, submain, and panel entries have developed for a longwall. These began operation in December 1986. Belt conveyors haul the coal from the mining sections to a 1.4-m (54-in.) belt located in the upper compartment of the slope. The lower compartment contains a hoist for men and material transport. From the slope, the coal moves to two 9 kt (10,000 st) raw coal storage silos, then to a 680-t/h (750-stph) preparation plant. After cleaning, a 5.5-km (3.5-mile) overland conveyor carries the coal to a clean coal slot storage and rail load-out facility. An electric locomotive then transports the coal to the Bonanza Power Plant in Utah. Allen-Bradley monitoring and control hardware and software controls the preparation plant, with two PLC-3 programmable controllers and a Process Control Industries D-1200 color graphics interface. The system operator uses three "smart" color video display units and an alarm printer for hard copy records. Originally, it also monitored and controlled the conveyors from the bottom of the slope to the top of the raw coal silos, the preparation plant, the overland conveyors, the main mine ventilation fan, and the hoist. Some of these features, though, were later transferred to the mine system.

Jan 2, 1988

By Peter J. Szabo

Many mining engineers tend to think of the economic analysis of mining ventures and projects on an f.o.b. mine basis. This is especially true of mines that are operated in an established domestic mining district. Here, transportation costs are many times smaller in comparison to overall delivered prices. One has only to consider the development economics of taconite mines in Minnesota with production destined for lower lake ports to see the truism of this statement. In the international arena, however, with consumers such as Japan and Europe located thousands of miles from source countries such as Brazil and Australia, the situation is different because mineral transportation is often a critical factor in determining project viability. This article is being presented to provide a basic understanding of the factors that govern ocean transportation of the three largest bulk mineral commodities shipped around the world: iron ore, coal, and phosphate. The major dry bulk commodity trades as a percentage of volume shipped are iron ore, 45%; grain, 25%; coal, 20%; phosphate rock, 5%; and bauxite and aluminum, 5%. Most of these commodities are carried by bulk carriers rather than tankers. These are vessels that have cargo, usually in solid form, loaded directly into the hold of a vessel by shore-side materials handling facilities or, in the case of a geared bulk carrier by the vessel's cranes and derricks. Gearless bulk carriers are used in most cases for iron ore and coal. Geared bulk vessels are mainly used for minor dry bulk trades such as ore concentrates (copper, lead, zinc, etc.), fertilizers (phosphate, potash, etc.), cement, petroleum, and coke. There has been, however, a trend toward using more self-unloading ships in both iron ore and coal ocean transport. And large vessels, such as the Universe Kure of Japan, have been designed with a cargo capability of 157 kt (155,000 dwt (deadweight tons)). Trade patterns of major bulk commodities are influenced by the Panama and Suez canals. Both of these canals have draft limitations that prohibit large, deep-draft, ocean-going vessels from using them for shorter trade routes used by Panamax and Suex vessels. The shipping industry has developed two widely used vessel classes; the Panamax and Suex vessels. The former is the maximum size vessel that can pass through the Panama Canal, usually 51-61 kt (50,000 - 60,000 dwt), depending on the season and draft of the vessel. The Panama Canal is usually 0.6-0.9 m (2-3 ft) deeper in the winter than in the summer. Thus, less cargo can be carried by the same size ship in the summer through the canal than in the winter. The Suex vessel is in the 71-81 kt (70,000-80,000 dwt) class. This larger vessel is able to transit the Suez since Egypt deepened the canal following the Seven Days War. Recently, the Suez Canal has been deepened to accommodate vessels with drafts as deep as 152 kt (150,000 dwt).

Jan 10, 1982

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 Anthony Peach, Lok Home

Introduction Raise boring is the most accepted form of mechanized hard rock boring in the mining industry. It appeared logical to take this mechanization one step further by introducing computers. Atlas Copco Jarva has produced a series of raise boring models that use an integrated computer. The company decided to use electronics and computerization, not for marketing purposes, but to make its equipment more cost-effective. Basis of Cost-Effective Design From the manufacturer's standpoint, it is possible for the equipment owner to reduce the cost of putting in raises by: • Replacing existing components with less expensive components that produce the same results; • Replacing existing components with more expensive components that make the equipment more productive; • Mechanizing equipment to reduce associated labor costs; and • Combining the above. Analysis of a standard raise boring machine (RBM) system showed that little could be done with less expensive components. It appeared, however, that the RBM could be more productive by transmitting more horsepower through the expensive drill string, while being precisely controlled by computers. An RBM system includes a basic machine, drill pipe, accessories, reamer, and cutters. The approximate percentage cost of various components on a standard system capable of boring 300 m (985 ft) long and 3-m-diam (10-ft-diam) aises in medium to hard rock is shown in Table 1. Also shown is the increased cost above standard of the Jarva computerized machine, and the productivity of both. Increased Productivity Penetration is important during the reaming cycle for more productive raise boring. This is possible by increasing the cutter load with constant rpm or increasing the rpm with constant cutter load. To increase thrust and maintain rpm requires increased capacity in the cylinders, drive train, main thrust bearings, drill string, electrical motors, and power units. To increase rpm and maintain cutter load requires only increased capacity in the electrical motors and power units. This is possible because the torque requirement remains constant for a constant thrust load. Only the horsepower increases, proportional to rpm. Since cutter costs are a big factor in raise boring, changes in machine performance must be analyzed to assess the effect on cutter performance. With a standard or typical carbide cutter, as used on raise boring machines, the effects of increased thrust or rpm are shown in Table 2. The assumption is made that the base data is the current rpm and thrust range where the cutters are now operated. It is also assumed one variable is held constant while the other increases. The result of this comparison, approximately, is that a 50% penetration increase can be achieved with little or no increase in cutter cost if rpm is increased 50% and cutter load is maintained constant. A similar 50% penetration increase can be achieved with a 45% increase in cutter cost, if the cutter load is increased by 20% and maintained constant. From an equipment standpoint, it is significantly less expensive to increase rpm 50% than it is to in-

Jan 7, 1984

By Peter J. Szabo

Introduction There has been much said recently about the sophistication of Japanese management in turning out reliable, inexpensive products, such as cars and steel. Techniques include consensus management and quality control circles. These have been touted as prime reasons for inexpensive Japanese products. An often neglected, but major factor in the equation of cheap export goods is the role played by Japanese trading companies. These venerable institutions are a vital factor in Japan's overall strategy of keeping the price of raw materials at the absolute lowest levels. This is critical to the country's economy since the nation must import more than 85% of all its coal. A country that is so desperate for imported raw materials would appear, at first glance, to be at the mercy of its suppliers. In Japan's case, however, the opposite is true. With the exception of brief' windows in 1974-75 and 1980-81, Japan has been in the driver's seat in negotiating contract terms. Due to its dominant role in world coal trade, Japan's situation can be described as a de facto monopsony. By definition, a monopsony is a market situation where the product, in this case coal, is offered by many sellers, but is sought by one buyer. This has been due to the role of Japanese trading companies in dealing with suppliers. Table I depicts trading companies by size in 1982. Mitsubishi and Mitsui are overshadowing in terms of size. The others, though less significant, play a vital role in orchestrating the marketplace. Three critical building blocks on which the strategy of the trading companies are based include intelligence networks, exceptional training of company traders, and shrewd contract negotiation practices. Intelligence Networks All success is derived from these three key components. Of the three blocks, intelligence gathering is the most important. With all the sophistication of the Central Intelligence Agency, the Federal Bureau of Investigation, Interpol, and the Surete', the Japanese trading company's method is every bit as competent and far more gentlemanly. Friendly competition is the key to survival. Although one Japanese trading company appears to be in ardent competition with its rival Japanese trading companies, when studied closely, a totally different picture emerges. The end user nominates certain trading companies as market channels and informally guarantees they will receive compensation regardless of which company wins a specific order. With this concept in mind, the pressure is off. The trading company can aim at getting the best price for the end user. Therefore, bargain, beat, and share information. Do whatever is necessary, but get the lowest price for the end user. Even with the game so gentlemanly, no victory could be assured without an adequate intelligence network. Proper intelligence is only as good as the sources drawn from. But how is one assured of getting the right information? The answer is verification. Verification is comprised of numerous independent sources each cross checked at a central processing unit in Tokyo. Each major Japanese trading company receives input, not only from its own trader, but from other trading companies as well. In addition to their own compilation, trading companies rely on the The Coal Manual, published annually in Tokyo by TEX. This manual covers every major coal producing country. Mines are located and seams identified, mining recovery, equipment lists, washing yield, railway distances

Jan 1, 1985

By Keith G. Papke

Industrial-mineral mining started early in the history of the State when salt was extensively mined for use in processing gold and silver ores, and borates were produced to meet most of the world's needs. After this start, industrial-mineral production grew slowly until World War II, mostly because of the remoteness of the State and the small population. Nevada now has a large and varied industrial-mineral industry. In 1983, 14 principal commodities were produced from 48 deposits; the total value of these materials was 168 million dollars. Nevada ranks first in domestic production of barite and magnesite; second in diatomite, gem stones, and lithium; third in fluorspar; and sixth in gypsum. Other materials produced are carbonate rocks, cement, clays, decorative and crushed stone, light- weight aggregate, perlite, pyritic soil additive, salt, sand and gravel, and silica. From 1978 through 1982 barite was the most important commodity; in 1983 diatomite surpassed barite in value of production. Most of the Nevada production consists of high-value commodities that are consumed out of the State. Approximately 430 significant deposits with 20 principal commodities are present in Nevada. This abundance can be attributed to the numerous and diverse geologic processes that have been operative. Seven major modes of origin have been identified: hydrothermal activity, sedimentation, combined hydrothermal activity-sedimentation, evaporative precipitation, brine formation, extrusion of igneous rocks, and alteration by ground water. The hydrothermal type accounted for 39 percent of the deposits, the combined hydrothermal-sedimentary type for 28 percent, and the sedimentary type for 13 percent. Nevada diatomite production is about 200,000 short tons/year valued at 30 million dollars. In 1984 three companies operated in Nevada producing diatomite from six open pits and processing it at four plants - one plant producing filter-grade materials and the others adsorbents and fillers. The diatomite occurs in about 60 areas, almost all in the western one-third of the State. The diatomites were deposited in long-lasting, fresh-water lakes in topographically closed valleys formed by basin-and-range faulting. About 85 percent of the barite mined in the United States is produced in Nevada. In 1981 the high point of production,-2.5 million short tons of bedded barite was produced from about 30 open-pit mines. About 120 significant bedded-barite deposits are known in Nevada; 38 of these have had past production of more than 25,000 short tons. The deposits are associated with marine siliceous rocks of Cambrian through Devonian age and occur in a zone about 300 miles long and 60 miles wide. Abundant evidence supports the theory that the bedded barite is of exhalative sedimentary origin.

Jan 1, 1987

By William R. Nash

Introduction As ore grades decline and deposit depths increase, problems and costs of mining construction increase rapidly. Ground water greatly impacts the cost of mining construction. In developing or exploiting ore bodies or coal mines, stored ground water in waterbearing formations is often encountered. Man-made conduits or shafts are constructed, as are raise bores for ventilation (up to 6-m-diam or 20-ft-diam), or smaller diameter drill holes, used for either power cables or rock dust. In underground construction and mining, it is possible to inherit unmapped and abandoned drill holes either from oil or gas exploration, or from previous geological investigations. There also exists within underground work exposure to faults, fissures, and jointing. A mine development may encounter unknown aquifers or, unluckily, have an ore body that is an aquifer. Water may invade an existing underground structure, due to concrete deterioration or to damage that may occur to an existing shaft or tunnel concrete lining. An underground development may intersect a drill hole that was not properly grouted when abandoned. It subsequently formed a conduit or an active path to conduct water into the mine. Water inflow may range from insignificant to a magnitude sufficient to inundate an area or an entire underground development. Corrosion imposes major costs. In shafts, it can cause accelerated wear and deterioration, and subsequent early replacement of hoisting ropes. It can also cause deterioration, misalignment, and subsequent accelerated wear and replacement of timber and steel guides and buntons. Utility maintenance (power cables, air, water, and ventilation lines) also can become a problem. Corrosion imposes major costs. Skips and skiploaders provide a never-ending series of maintenance headaches when exposed to an ingress of water. Numerous problems are found in declines with invert and rail maintenance and with partitions in over-under coal mine slopes. Ground water interacting with an underground ventilation system can result in: • Increased ventilation resistance due to roof falls and the spalling of ribs caused by ice heaving. • Restriction in shaft or slope cross-sectional area due to ice buildup during winter months. This may be a safety hazard to access as well. • An increase in the moisture content entering the ventilation air that condenses underground and causes electrical and equipment maintenance problems. Underground structures also incur water-caused problems. The concrete lining in shafts, slopes, and tunnels may be subject to: • Active mine waters causing concrete and reinforcing steel to deteriorate - perhaps to the point of collapse. • Load redistribution around a concrete lining, caused by soil dislocation due to water movement. The resulting stress may be in excess of the calculated design loading. Backwall injection with grout of the completed concrete lining may solve these water inflow problems through low-pressure injections of cement and chemicals. This fills voids at the interface of the concrete lining with either the soil or rock excavation. Surface structures may be jeopardized by lowering the ground water table, resulting in surface settlements. Surface settlements can occur in buildings, headframes, hoist foundations, mills, conveyor structures, or in rail haulage. Areas of differential settlement can lead to derailments, improper wear of hoisting ropes on sheaves in headframes, and the misalignment of bearings and brakes. Mud jacking and compaction grouting may remedy these problems. To reduce operating costs, increase efficiency, and increase safety, inflow water to the mine should be minimized. For an operating mine with a water problem, a water inflow survey should be taken. Quantities of water flow should be examined at all accesses (shafts, slopes, bore holes, and raise bores) at the faces, haulages (rails or conveyors), and sump discharge. From this examination and quantity survey before and after heavy rainfalls, valuable data for elim-

Jan 3, 1984

By Robert S. Hedin, David M. Hyman

Acid mine drainage (AMD) is a common water pollution problem on active and abandoned coal mine sites in the eastern United States. AMD forms when surface mining brings unweathered pyrite-containing rocks to the surface or when deep mining allows oxygen to contact buried pyritic strata. In the absence of neutralizing compounds, the drainage that results can be extremely acidic and contaminated with dissolved iron, manganese, and sulfate. Drainages with pH < 3.0 and concentrations of sulfate greater than 1,000 mg/L, iron greater than 50 mg/L, and manganese greater than 10 mg/L are common. Where water flows through alkaline materials (such as limestone) before surfacing, the drainage is less acidic and occasionally circumneutral, but it can still contain high concentrations of sulfate and metals. Current water quality standards in the United States require that mine discharges have a pH between 6 and 9, total iron concentration less than 3.0 mg/L, and manganese less than 2.0 mg/L. At thousands of active and inactive mine sites, drainage does not meet these standards and is being treated before discharge by the mining company. At thousands of other sites, which were abandoned prior to the enactment of water pollution laws or were operated by companies that have gone bankrupt, untreated AMD is polluting receiving water systems. The standard mine drainage treatment system involves the addition of a1 kal ine chemicals to the water, which raises the pH and cause metals to precipitate in a settling pond. These systems are expensive, often costing tens or hundreds of thousands of dollars per year for chemicals, operation, maintenance, and disposal of the metal- laden sludge. Because the drainage on many sites will likely be contaminated for decades, there is financial incentive to find alternative water treatment systems. In the last five years, many mining companies and engineering firms have experimented with the construction of wetland treatment systems. Very few of the several hundred wetland systems that have been built are performing well enough to justify total abandonment of chemical treatment. Nonetheless, systems continue to be built because the mining companies have found that wetlands can reduce their AMD treatment costs. It is also their hope that further research and development will eventually result in systems that will completely rep1 ace chemical treatment and offer long term performance at minimal cost. The Bureau of Mines has been actively involved, from a research perspective, with this approach to AMD treatment since its inception. In this paper, the status of constructed wetland technology is discussed with respect to the construction and performance of systems, chemical and biological processes that affect AMD chemistry within constructed wetlands, and the future of this technology as perceived by the Bureau of Mines. ORIGINAL OBSERVATIONS The constructed wetland concept has its roots in observations of natural Sphaqnum peat wetlands that received acid mine drainage and, instead of being adversely affected, appeared to cause an amelioration of the polluted water (Huntsman et al. 1978; Wieder and Lang 1982). These observations instigated the idea that wet1 and systems might be used for the intentional treatment of mine drainage. Because the discharge of AMD into a natural wetland is prohibited in the U.S. by several laws, it has been necessary to construct wetlands which act solely as water treatment systems. Initially, most wetland research and construction efforts mimicked the original observations by utilizing Sphaqnum moss and peat. Despite promising laboratory results (Kleinmann et al. 1983; Tarleton et al. 1984; Burris et al. 1984; Gerber et al. 1985), virtually all field tests of Sphasnum-dominated constructed wetlands failed to provide sufficient water treatment for more than several months. Sphasnum proved quite sensitive to the stresses associated with transplanting, abrupt changes in water chemistry, excessive or insufficient water depth, and

Jan 1, 1989

By A. K. Mukhopadhyay, B. Sikdar, V. P. Arora

Introduction During the past several years, persistent concerns about an economic slowdown in India have tempered capital-expan¬sion plans. This has encouraged companies to find methods of increasing the capacity of existing production equipment. One of the more cost-effective methods of increasing produc¬tion capacity without major capital investment is to improve equipment maintenance to prevent needless machine down¬time. This can have a significant financial impact because of reduced maintenance costs and increased machine availabil¬ity. The maintenance program employs different techniques, but the analysis of the vibration behavior of machine compo¬nents to assess their condition was found to be the most accurate technique for monitoring various machine disorders. A dragline that handles overburden in open pit mines is one of the more capital-intensive pieces of production equip¬ment. It is imperative that the machine be run at its optimum capacity under the prevailing environmental conditions. Condition monitoring of the various components of the dragline through vibration analysis not only improves the machines availability but also ensures a long operation time free from sudden failure. This paper describes the application of vibration monitor¬ing and analysis techniques to assess the components of a W2000 dragline. The paper reveals that condition monitoring through vibration analysis can be as valuable in failure prevention as it is in failure analysis. Finally, the paper presents an approach to a knowledge-based expert system to the quick and correct diagnosis of mechanical faults in a dragline. Equipment A dragline is an intermittent-discharge-type excavator having a long boom at one end. Unlike other excavators, the bucket is not rigidly held by the frame structure. In favorable geomining conditions, the intensive operation of these exca¬vators is the least-expensive means of overburden removal. The basic working elements of this equipment are the hoist system, the crowd and retract system, the wing mechanism and the propel mechanism. The walking dragline is accepted as the most economical machine for stripping overburden at depths of up to 60 m (200 ft). They are electrically powered and the various motions are effected by individual drives. The Ward-Leonard system is used to provide the optimum flexibility in controlling different dc-drive motors. To mini¬mize the cost of mineral extraction, the largest such machine in India has a 24-m3 (850-cu ft) bucket with a boom length of 96 m (315 ft). Draglines are very costly, and considerable financial penal¬ties may arise from sudden stoppages due to component fail¬ures. Thus, operational reliability is of the greatest importance. Active measures are now being taken to minimize downtime by adopting condition-based maintenance techniques. Though a number of techniques come under this scheme, it has been observed that assessing the health of the dragline by measuring vibration is the best method of determining the dynamic behavior of its various rotating components to avoid any catastrophic failure. Based on criticality, the vibration-behav¬ior of the following components are studied: • motor-generator unit, • exciter unit, • hoist motor-gearbox unit, • hoist drum-gearbox unit, • drag motor-gearbox unit, • drag drum-gearbox unit and • swing motor unit The approach Increases in the vibration levels in different subsystems of the dragline were observed due to the presence of faults such as unbalance, misalignment, looseness and bad bearings. A vibration behavior study included the measurement of vibra¬tion level, trend analysis of time-domain vibration signals and vibration frequency analysis at bearing points of the components. A vibration meter, a vibration analyzer and a data collector are used. Vibration-level measurement. When the dragline was assembled and put into operation for the first time, vibration data were collected to generate baseline data for the equip¬ment (based on International Standard ISO 2372). After¬wards, the vibration levels were recorded regularly using a vibration meter. The measurements were taken at all bearing

Jan 1, 2000

By Peter Zhang, Daniel Su, Bo Hyun Kim

Shale gas wells drilled in longwall chain pillars are influenced by longwall mining. Longwall mining on each side of the chain pillars can create overburden movements and induce deformations in gas well casings. If the deformations result in a casing breach, intrusive shale gas could leak into the longwall mine with serious safety consequences. This study concerns five shale gas wells in the chain pillars between two adjacent longwall panels in the Pittsburgh coal seam under a cover depth of 670 ft and a mining height of 7 ft. The gas wells were constructed with typical casing design, but a casing cementing alternative with uncemented production casings was practiced. Four production casings were uncemented, and one production casing was unintentionally cemented with good quality cement to a 535-ft depth and low-quality cement stringers from a 444- to 535-ft depth. The longwall faces passed by the shale gas wells as each adjacent longwall panel retreated. Production casings were surveyed by a multi-finger caliper after each panel was mined. No deformation was detected in the four uncemented production casings, but small deformations were detected in the partially cemented production casing. The maximum measured deformation in the cemented production casing was 0.05 in. after first panel mining and 0.06 in. after second panel mining. The casing deformations were also predicted by the FLAC3D model set up on site-specific overburden geology. The predicted deformations were in good agreement with the measurements in terms of deformation locations and magnitudes. All five shale gas wells resumed normal production after being temporarily plugged during the period of mine-by. This study provides a successful demonstration of the effectiveness of a casing cementing alternative for decoupling production and intermediate casing, and thus minimizing the influence of longwall mining in the shale gas wells drilled through longwall chain pillars.

Jul 1, 2023

By B. R. T. Simoneit

The formation of petroleum is normally thought of as a geologically lengthy process, involving the accumulation of organic matter, its gradual burial, diagenetic breakdown via geochemical reactions, maturation, heating within a 75-150&apos;C "oil window" induced by normal geothermal gradients in the subsiding basin, and slow product migration into structural traps (Tissot and Welte, 1984, Hunt, 1979). The entire process can take millions of years and, indeed, most oil reservoirs probably formed in this manner. How-ever, today in sedimented, submarine rift basins (Fig. 1), Cl to >C40 hydrocarbons with the chemical and physical properties of crude oil are forming in demonstrably much shorter time by rapid thermal maturation of immature organic matter in hydrothermal regimes that are unusually high for sedimentary basins (Brault and Simoneit, 1988a, b; Didyk and Simoneit, 1988; Kawka and Simoneit, 1987; Peter et al., 1988; Simoneit, 1983; 1984; 1985a,b; 1988; Simoneit et al., 1984; 1987; 1988).

Jan 1, 1989

By G. D. Bates

INTRODUCTION The Magmont mine is a joint venture of Cominco American Inc. (operator) and Dresser Minerals, Inc. The mine-mill operation is located approximately 160 km (100 miles) southwest of St. Louis, MO, in what is commonly referred to as the "Viburnum Trend.” The Magmont mine is designed for a production rate of 3810.2 t/d (4200 stpd) on a 5-day week, three shifts per day basis. Initial production began in 1968. The mine is open stope, room-and-pillar, and essentially horizontal along the trend of the ore body. Briefly, the main geological structure can be described as a brecciated graben bounded by reverse faults. The ore body in cross section is shaped like a bell curve with some lateral extension at the lower part. Presently outlined ore is 609.6 to 762 m (2000 to 2500 ft) in width and 2133.6 m (7000 ft) in length. The ore varies in thickness from 4.87 m (16 ft) on the fringes to an average of 27 m (90 ft) in the high ore areas bounded by the reverse faults. Lead is the primary metal with zinc and copper secondary. MINE DESIGN The basic design of open stope, room-and-pillar mines has been described by several writers and need not be repeated here. (Anon., 1970; Bullock, 1973; Casteel, 1972; Christiansen et a]., 1970; and Lane, 1964) This discussion covers the mining sequence as applied to the particular problems at the Magmont mine, the use of equipment, and deployment of the work force. In the upper portion of the Magmont ore body is a layer locally called the False Davis shale. This layer lies below the true Davis shale, is normally interbedded with dolomite, is of varying thickness, and if mineralized, is included in the top pass of the mining sequence. In thick ore areas this layer will be 2.13 to 2.43 m (7 to 8 ft) in thickness and will occur in the upper portion of the pillars. Due to its incompetency the presence of this False Davis layer is of primary concern in mine planning and operation. Mining areas are divided into three basic groups by ore thickness. First are areas of ore up to 6.09 m (20 ft) in thickness. These areas are below the False Davis shale and are mined single pass with drill jumbo. Second are those areas up 13.71 to 15.24 m (45 to 50 ft) in height. The first 4.87-111 (16-ft) Pass is taken at the top of the ore and the back and pillars secured. Benching the lower portion(s) in 4.57 to 4.87-m (15 to 16-ft) passes is then done with either a drill jumbo drilling horizontally or a crawler drill drilling vertically. Normally these areas are below the Table 1. Productivities per Manshift False Davis shale. These areas may also be mined by back slashing, or overhand benching, where the first 4.87-m (16-ft) pass is taken at the base of the ore and successive 4.87- m (16-ft) passes are taken upward. A minimum amount of back slashing is done at Magmont since it requires repetition of roof control on each pass and roof control is the single largest stoping cost at Magmont. Ore left to provide a working platform oxidizes and is coated by oil spills thus reducing metallurgical recoveries. The third mining area is over 15.24 m (50 ft) in height UP to a maximum of 40.23 m (132 ft) and will encompass the False Davis shale. These areas are mined by first driving +15% inclines to the top of the ore body. The top pass is mined and the back is bolted and roof mats installed as a matter of standard practice to minimize roof problems as mining progresses downward. Once the back and pillars on the top pass are secured, benching begins on successive passes with either the drill jumbo or crawler drill. Pillars on all successive passes below the top pass are secured as necessary. While benching progresses below the top pass, the pass at the base of the ore body is mined leaving a sill of 4.57 to 7.62 m (15 to 25 ft) in thickness to be removed with the crawler drill in a retreating manner. Rooms are mined on a 1.57 rad (90") grid pattern to insure alignment of pillars where multiple passes are taken. Pillars are designed on a 17.98-m (59-ft) spacing with rooms up to 10.66 m (35 ft) in width. Heading widths are wide enough for the mobile equipment to turn without additional allowance for curves. The result is a flexible layout which provides a maximum number of headings available for high extraction rates and grade control. PRODUCTION Incentive Bonus Incentive bonuses play an important part in the mine production at Magmont. Production crews are trained to perform only one of the mining functions of drilling, blasting, mucking. or roof bolting. This specialization, or functionalization, is augmented by development to open all possible stoping areas as early as possible in the life of the mine. This insures that each crew will have enough headings to perform its specialty. The incentive bonuses increase exponentially as output increases. The lucrative incentive bonus coupled with the specialization of the production crews and proper mine development have combined to give the high productivities shown in Table 1. Development crews perform all mining functions in their area. The incentive bonus is paid on a per foot basis, Crews on different shifts working the same heading share equally in the bonus proportional to their contract hours worked.

Jan 1, 1982

By Ruckmick J. C.

Elemental sulphur occurrences are widely distributed in two geological environments: -1-Basins containing hydrocarbons and zones of Cenozoic vulcanism. However, very few of these constitute deposits large enough to be of commercial importance. Almost all of the elemental sulphur mined in the world comes from bioepigenetic deposits in petroliferous basins. These deposits occur in two general structural styles: diapiric (salt domes) and stratiform. Examples of diapiric deposits occur in the Gulf Coast basins of Texas, Louisiana, and southern Mexico. Examples of stratiform deposits occur in the Fergana and Amudarya depressions of Central Asia, the Mesopotamian Depression in Iraq, the Cis-Carpathian Trough in Poland and Russia, and the Permian Basin in Texas. Economic bioepigenetic sulphur deposits range in size from approximately 1 million tons of sulphur in the smaller salt dome deposits to more than ZOO million tons of sulphur at the Mishraq stratiform deposit in Iraq. Total world production from bioepigenetic deposits amounts to approximately 16 million tons of sulphur per year, one-half of the world&apos;s present annual consumption of elemental sulphur. Most of the balance of the annual consumption is recovered from sour gas and petroleum. All bioepigenetic sulphur deposits share remarkably similar origins and characteristics. They are formed by anaerobic bacterial replacement of gypsum or anhydrite in tilted basins where evaporite beds are underlain by petroleum. Figure 1 illustrates a generalized cross-section of a salt dome sulphur deposit. Figures Z, 3, and 4 are cross-sections of three types of stratiform sulphur deposits. In terms of sulphur genesis, the only significant difference between the salt dome and stratiform deposits is that the positioning of the anhydrites above the petroleum in the salt domes is caused by diapiric rather than sedimentary processes. In the salt domes, the residual anhydrites of the cap-rocks are accumulated by solution and removal of halite by artesian ground waters.

Jan 1, 1978

By Henry A. Russell

During the last ten years Parsons Brinckerhoff has become a leader in the area of tunnel rehabilitation. A significant part of any tunnel rehabilitation program is the control of groundwater infiltration into the structure. This leakage over time, causes deterioration of the structures, and creates numerous operational problems for the tunnel operator. This paper will address current procedures for identification, documentation, and recommendations of repair methods for the control of groundwater infiltration in rail and highway tunnels.

Jan 1, 1993

By Christopher J. Hall

This paper describes the results from computer runs simulating 24 different mine ventilation configurations with the main fan situated first at the top of the upcast shaft and then at the top of the downcast shaft. Real air was used, with evaporation, condensation and heat exchange. The results showed that power requirements for the forcing fan were up to 20% less than for the exhausting fan for equal mass flow rates.

Jan 1, 1989

By R. Kadeg, S. Pavlou

A methodology for developing and utilizing risk-based action levels for soils in site closures is discussed. The methodology is based on standard exposure pathway models which are consistent with current regulatory guidance on conducting risk assessment. A simple approach to evaluating the potential for contamination ground water from the projected criteria based on the Toxicity Characteristic Leachate Procedure (TCLP) is also presented.

Jan 1, 1992

By R. Codell, D. L. Hughson

The authors benchmarked the integrated finite-volume code MULTIFLO against the analytical solution of Philip et al. (1989) for cylindrical underground openings. They found that the numerical simulation of dripping threshold flux was consistently higher than the analytical solution for rectangular and unstructured grids. The magnitude of this error was proportional to the alpha parameter characterizing capillarity. This error may bias estimates of seepage into drifts for repository performance towards nonconservatism.

Jan 1, 2002

By J. F. Whelan, B. D. Marshall, Z. E. Peterman, J. B. Paces, L. A. Neymark

Observations of calcite and opal in cavities in the unsaturated zone at Yucca Mountain indicate that: 1) seeps are not regularly spaced in underground workings and not all fractures sustain flow, 2) many cavities represent sites of seepage that have remained stable for millions of years, 3) typically there is no evidence (such as dripstone) for seepage dripping into cavities from their ceilings, and 4) seepage is not likely to be greater than about 1 liter of water per year (per 5-m-long drift) based on calcite abundances observed in the ESF. This estimate of seepage is significantly lower than that used for performance assessment.

Jan 1, 2000