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By Peter P. Harvey

The Nonel Primadet is a non-electric blasting initiation device. The system incorporates the safety advantages of a cap and fuse system with the precision blasting afforded by electrical blasting caps. Each unit is made up of a delay blasting cap factory-crimped to a Nonel® shock tube lead line. The delay elements in the blasting caps are manufactured in both millisecond and long period series. There are 16 periods available in both series - period 0 through period 15. The units are manufactured in 12', 16', and 20' lead lengths. The hollow shock tube is made of surlyn plastic and it is coated on the inside with a reactive material. The powder train has a density of only 1/10 grain per linear foot of tube. A typical blast round is timed precisely the same way it would be with electrical caps. After the round has been timed and loaded, the tube leads are gathered in convenient bunches and tied into a detonating cord trunkline. The Nonel® tube bunches are initiated by the output of an 18 grain per foot detonating cord trunkline. Once initiated, the Nonel® shock tube will reliably propagate at 1800 meters per second. The energy from this shock front initiates the delay elements in each delay cap. The shock tube is inert to electrical energies, including; stray current from AC/DC power sources, as well as, electrostatic discharges. The tube is also inert to initiation by impact. The system has proven to be particularly advantageous in both tunnel and shaft blasting applications. The major advantages in using the Nonel® system in this type of work are: 1) faster and easier tie-in techniques through the use of bunch-blasting. 2) electrical power can be left on during loading and tying-in. a. electrical lights can be turned on at the working face - better lighting facilitates loading and tying-in. b. electrical pumps can continue to function throughout loading and priming procedures (this is particularly advantageous in shaft work with water problems). 3) down-time due to approaching electrical storms is minimized. 4) increased overall efficiency in the blasting cycle: a. it is easier to train a man in the proper use of the system. b. fewer missed holes per round. c. less time required for tie-in. 5) safety-advantage--The system is not susceptible to involuntary initiation from extraneous electrical energies.

Jan 1, 1979

By Y. C. Kim

For the past quarter of century, much more effort and research have been expended in developing the "optimum" ultimate pit limit design algorithms and much less to solving the "optimum" open pit production sequencing. However, the potential economic benefit to an operating mine is far greater for the latter than the former. Unfortunately, the problem of "optimum" open-pit production sequencing has not been fully solved to date. This paper first reviews the past and currently used methodologies for developing this sequence. The staggered pit phase geometry problem of advanced stripping and operational constraints such as ore and waste tonnage requirements by period and necessary contiguity of mining faces are the main reasons why the "optimum" production sequencing problem has not been solved as yet. This paper also explains why any method which attempts to simplify the problem using ultimate pit limit design algorithm will fail to reach an "optimum" solution.

Jan 1, 1994

By C. A. Moseley, M. B. Kahle

The Gulf Coast Region has been the center of extensive lignite exploration and development activity in the past 10 years. Currently, 27.2 Mt (30 million st) of lignite are mined annually, the majority of which is uncovered by large walking draglines. Projections indicate that production could reach 125 Mt (138 million st) by 1990. As mining moves to deeper depths, removal of overburden becomes the decisive factor in mine planning and cost. The geology of a region plays a key role in the selection of an overburden removal system. While alternate stripping methods must be analyzed to determine the most economical and operationally sound method, so far bucketwheel excavator systems seem to be the best method for removing large volumes of soft, unconsolidated material that is found at projected mining depths in the Gulf Coast region. Geology of Gulf Coast Lignites Extent Distribution of the principal tertiary lignite-bearing deposits in the Gulf Coast Lignite province extend from the Texas-Mexico border to the Alabama-Georgia state line (Fig. 1). The lignite-bearing strata includes portions of eight states: Texas, Louisiana, Arkansas, Missouri, Kentucky, Tennessee, Mississippi, and Alabama. Lignites occur primarily in the Wilcox, Claiborne, and Jackson groups in the Gulf Coast. The uppermost strata of the Midway group in Mississippi and Alabama also contain significant lignite resources. Reserves Commercial lignite seams in the Gulf Coast Lignite province range from 0.6-3 m (2-10 ft) in thickness. The estimated lignite resources throughout the Gulf Coast in seams greater than 0.9 m (3 ft) in thickness and up to 61 m (200 ft) in depth currently are estimated at 32 Gt (35 billion st). Table 1 shows these resources by state. Quality Lignite quality can vary within individual mining areas and seams. However, trends in quality occur because of the depositional environment, age, and west-to-east geographical location. Better quality lignites occur in the Wilcox group in Texas and Louisiana. Poorer quality lignites occur in the northern regions of the Wilcox group and those of the geologically younger Claiborne and Jackson groups. Environmental Conditions Gulf Coast province environmental conditions are ideal for successful mine reclamation. The lignite occurs in flat to moderately rolling terrain, a topography easily reproduced from the spoil dumps or spoil rows developed during the mining operation. High to moderate rainfall facilitates rapid revegetation. Evidence from current mine reclamation programs and ongoing test plot studies indicate that mined lands can be reclaimed to reach premining productivities. Sometimes productivities are even greater than that of premining conditions. Existing Mining Methods Present Mines & Production There are seven active mines in the Gulf Coast province, all located in Texas (Fig. 2). Lignite

Jan 8, 1983

By Harrison R. Cooper

INTRODUCTION AND SUMMARY Phosphate matrix beneficiation is the process of providing a mineral product suitable for downstream chemical processing to yield high analysis chemical fertil- zers. Extraneous contaminants, clays and gangue solids, are separated by screening and flotation. Reject materials always carry with them some phosphate mineral values, however. A continuing objective is minimizing phosphate losses discarded with tailings as a principle factor in maintaining beneficiation efficiency. The quest for efficiency, and improved productivity, during beneficiation is hampered by disturbances arising from among the following: o Natural variance of phosphate deposit compositions, o Minimal control over managing ore matrix supply to the plants, o Screening and flotation mechanical upsets and inefficiencies. Production personnel, in recognizing these factors, attempt corrections for changed process conditions. This response usually has limited effect. Efforts of product- ion personnel to correct for upsets of the process may often diminish efficiencies rather than improve them. Lack of prompt data for analysis of process streams is an important contributing cause of inefficient operation. Discussion in this paper examines methods for improved process control in Florida phosphate beneficiation with particular emphasis on use of on-stream analysis to aid gaining productivity. The Florida Institute of Phosphate Research has supported demonstration of on-stream analysis applicable to improved process control. Concurrently, work is proceeding world-wide in the phosphate industry toward practical on-line analysis technology. Table 1 summarizes viable methods for real-time analysis data as result of work by individual companies and research organizations. A recently completed investigation (sponsored by the Florida Institute of Phosphate Research) of beneficiation efficiency was carried out in two Florida beneficiation plants using a newly developed on-stream analyzer for phosphorus (1). BPL measurements were taken at frequent intervals over two to three weeks of routine operation. Grades are expressed in "BPL", with one BPL, or bone phosphate of lime unit, equal to 0.46 P^Y2^YO^Y5^Y. The time series of feed and tailing BPL data were evaluated by statistical procedures. Results show avoidable losses can be five per cent or greater of mineral values in feed. Use of modern process control methods in Florida phosphate mining began several years ago (2, 3). Benefits of stabilizing control used in one of the two plants where data were collected for the investigation, in comparison to manual control in the other, are outlined. Process control technology developments reported from European and South African phosphate mining operations are also noted (4, 5). It is now well accepted that advanced control techniques can increase beneficiation productivity by better management of losses. However, to make advanced control effective, real-time measurements are needed of feed and tailings BPL as well as mass flow rates.

Jan 1, 1993

By A. MacG. Robertson

INTRODUCTION The tailings, or solid waste, remaining after uranium has been extracted from an ore and the liquid wastes associated with it contain both radioactive and other substances which, if released to the environment, may have a detrimental impact on man and his environment. Although the radioactivity of the waste is of natural origin, the mining and milling process results in bringing the radioactive ore to the surface, changing its chemical and physical form, increasing its mobility and, therefore, enhancing the potential radiological exposure to man. Exposure to radionuclides released from a tailings impoundment, while small as applied to any one generation, can be made large by counting far into the future, large enough to be the dominant source of exposure from the nuclear fuel cycle, Cunningham (1978). Increasingly it is being found that where the prime concern was initially the radionuclide releases, the release of other pollutants and contaminants may be of equal or greater concern. While there is a definite benefit, at least to present generations, resulting from the recovery of uranium, current and long-term concerns require that consequential present and future releases be kept as low as is reasonably achievable. Design practice, to minimize this release, is currently passing through a technical revolution; precipitated by public and institutional concerns. New techniques and methods are, therefore, being actively sought and continuously implemented. Because of the complexity of the pollutant release mechanisms and the sitespecific nature of each impoundment site and tailings product, a wide variety of site selection and design options have been implemented or considered. It is often possible to design a number of satisfactory tailings disposal schemes which differ widely in nature and cost. This paper outlines the principal areas in which options are available and discusses some of these options. Both operating and post-decommissioning conditions are consi-

Jan 1, 1980

By Charles H. Tiernon

Separation of particles on a table deck* results from differences in specific gravity, plus a number of other interrelated phenomena: size of particles; shape of particles; stratification (consolidation trickling); and hindered settling. The effective use of these factors may be controlled and aided by the following table adjustments: differential action of the drive or head motion; speed of motion; length of stroke; side tilt; end elevation; size of deck area; shape of deck; character of deck surface; riffle design; amount and distribution of wash water; feed water-to-solids ratio; feed rate; and feed uniformity. The typical concentrating table used in the US coal industry is essentially a rhombohedral-shaped deck supported by a suitable subframe. It generally slopes in the direction of the short axis, tilts upward at the refuse end of the long axis, and is differentially reciprocated in the direction of the long axis. This head motion tends to move the particles longitudinally toward the end of the table. At right angles to this movement, wash water (distributed along the high side of the table) tends to move particles down the slope parallel to the short axis of the table. Hence, the natural path of a particle on a concentrating table is from the feed box corner to the diagonally opposite corner of the deck (Fig. 1). There is a natural tendency for heavier particles to sink to the deck of the table and for lighter particles to stay nearer the surface. As a consequence, the heavier particles are carried further along the longitudinal axis since, being on or near the surface of the deck, they are more affected by the table's reciprocating action. The lighter particles, being at or near the top of the moving bed, travel slower in a longitudinal direction and thus separate from the heavy particles. Wash water and the diluting water in the feed cause lighter gravity particles to move down the short axis of the table. The feed material then fans out from the feed box, where it enters onto the table with heavy gravity particles moving in one direction and lighter particles moving in another. By properly adjusting all of the previously mentioned factors, a clear-cut separation is possible between high- and low-gravity particles, or between refuse and coal. Riffles are of great importance to tabling. They create considerably more capacity than is possible with smooth decks, and they are responsible for better separation accuracy. Particles in their downward movement along the deck's slope are delayed behind the riffles. Hindered settling, consolidation trickling, and other phenomena occur as the particles tumble over the riffles and stratification ensues. The heavier particles settle to the deck of the table and are trapped behind the riffles, thus insuring their positive movement toward the end of the table. Since stratification and separation of particles are not complete as a result of any one riffle, a series of riffles are used. The cycle of stratification and hindered settling is repeated from riffle to riffle. The result is purer products as particles fan out and progress forward and downward over the table. The smallest, heaviest particles stratify downward to the surface of the deck more quickly and are carried out by table movement toward the refuse end at a faster rate than coarse, heavy particles. Light gravity, larger pieces ride on the top layer of particles and flow down the deck's slope as a result of the cross flow of wash water at right

Jan 8, 1980

By Rocky Gunderson

When operations begin early next year at the $100-million Port Kembla coal loading facility in New South Wales, Australia, a sophisticated computer system, directed by two of Hewlett-Packard's HP1000 mini-computers, will perform a number of functions ranging from monitoring and reporting arrivals and departures to maintaining a library of events for up to one year. The three-processor HP1000 system configuration, valued at $215,000, is one of the largest single orders, in terms of dollar value, ever submitted in Australia for Hewlett-Packard's line of engineering and manufacturing minicomputers. The processors will be linked in a fully "backed-up'' configuration using Hewlett-Packard's fourth generation distributed networking system, DS/1000-IV, making the system one of the most sophisticated in Australia. Interfaced to a number of weightometers and programmable logic controllers (PLCs), the computers will be the heart of a coal inventory system for the facility which, in its first phase, will be capable of handling more than 13.5 Mt/a of coal. The computers will report on all plant functions, including conveyor belt and water spray operations. Specifically, the system will: • Monitor and report all coal movements related to road and rail deliveries, dispatches from ship loaders, and interstockpile transfers. •Maintain a ''running log" of all events pertaining to overall plant operations, such as conveyor starts and stops and anti-pollution spray activation. • Accept and maintain plant data entered manually or acquired automatically from various remote locations via either visual display units (VDUs) or PLCs. • Maintain complete historical records of all transactions and related plant events for up to one year. • Provide a facility for stockpile management, modeling-type programs, and training or other simulation activity. The facility was designed with the following characteristics in mind, based on an analysis of requirements for an automated coal loading operation that would optimize productivity and be flexible to change and grow with facility needs and changing technology: • Continuous Operations-Due to the need for continuous plant logging and control, the overall facility will be capable of uninterrupted, 24¬hour operation. • Handling Current and Projected Workloads-The facility will be capable of not only handling current workloads, but also any additional workloads required during future coal loading operations. • Expansion-The facility will be capable of expansion, for a minimum cost, at any time with minimum disruption in operations. • Single Source of Supply and Maintenance-The facility will be supplied and maintained by one supplier, through hardware and software maintenance support contracts. System Configuration Two HP1000 minicomputers, each with 500K bytes of main memory, will be front-ended by a pre-processor with 256K bytes of main memory. These three systems, active, backup, and front-end, will be interconnected into a triangular array, as shown in the accompanying diagram. Under normal conditions, the front-end will transmit plant status data to one of the main systems, whose primary function will be to monitor coal flow and maintain a relevant dialogue with operators. The front-end, therefore, handles all communication with the plant PLCs, effectively removing this overhead from the current plant monitor (either of the two main systems). The front-end pre-processes and post-processes all information flowing from the plant monitor to the PLCs and vice versa, thus effectively handling all communication between the two units. A second main system will handle reporting, administrative, and modeling functions, and will also be capable of performing both front-end and monitoring operations. Linking all

Jan 11, 1981

By D. M. Bodily, V. J. Hucka

INTRODUCTION Interest in the recovery of methane from coalbeds has increased rapidly over recent years, because of its potential as an energy resource and to alleviate pollution and safety problems. The resource base of coalbed methane in the United States has been estimated at 11.2 Gm3, roughly equivalent to 20 years consumption (Mroz et al., 1983; Kuuskraa and Brandenburg, 1989). Methane contributes to the adverse environmental impacts of global warming, tropospheric ozone formation (smog), and potentially stratospheric ozone destruction. Association of methane with coal has always presented a safety problem in mines due to the potential for explosions. The rate of release of methane depends on the amount adsorbed by the coal, the adsorption isotherm for the coal, and the size of the coal particles. Mining operations can affect the particle size distribution and the production of fines and therefore the rate of release. The time the mined coal remains in the mine may also be important in determining total emissions. The methane content of some Utah coals was determined in this study. The methane content of the coals is compared with the chemical and physical properties of the coals and the properties of the seam and neighboring strata. Correlations are developed to better understand the formation and retention of methane by these coal seams. METHANE FORMATION IN COALBEDS Three mechanisms for methane formation may be considered: (1) nonbiogenic formation, (2) formation by anaerobic bacteria during plant material deposition and the early stages of diagenesis, and (3) formation from pyrolysis of coal material during coal maturation. Nonbiogenic formation by thermal processes involving carbon- and hydrogen-containing compounds has been proposed as a mechanism for methane formation in the earth. It is not likely to be of importance where other fossil fuel materials are present. Coal would not survive the temperatures required and hence the methane would need to migrate and be trapped by the coal seam. This mechanism is unlikely for coalbed methane. Formation of methane by anaerobic bacteria undoubtedly occurs during coalification, but the methane may not be trapped until the pore system of the coal is developed, and would likely be displaced by methane formed during further coalification. Methane formed by maturation of the coal material as it progresses from peat to coals of various rank is the most probable mechanism for the formation of coalbed methane. Most of the methane is adsorbed onto the walls of microvoids in coal. It has been estimated that the surface area of one kilogram of coal is between 20,000 m2 to 200,000 m2. Surface area measurements depend on the coal and also on the method of measurement. At 20 atmospheres, in some coals, the adsorbed methane is 10 times greater than methane as a free gas. At 100 atmospheres the adsorbed gas can be as densely packed as a liquid. The volume of methane gas held in coal depends on the volume of gas that exists as a free gas and the adsorbed gas capacity. The volume of free gas in the coal can be calculated from the kinetic theory of gases (methane can be assumed to be an ideal gas because errors would not be greater than 1 % for normal mining pressures). Langmuir (1916) derived an equation for the adsorption of gases on uniform surfaces and this is applied to the adsorption of methane on coal:

Jan 1, 1993

By M. J. Lowe

National Institute for Occupational Safety and Health (NIOSH) studies show that 43.5% of surveyed coal preparation plant workers had noise exposures exceeding the Mine Safety and Health Administration Permissible Exposure Level. Sound levels around vibrating screens in these plants often exceed 90 dB(A). NIOSH is currently developing noise controls for horizontal vibrating screens. To characterize noise sources, NIOSH researchers performed sound pressure level (SPL) measurements on a vibrating screen at their Pittsburgh Research Laboratory. The results show that the entire screen contributes to noise below 1 kHz and the vibration mechanism housings are most significant above 1 kHz. Constrained layer damping (CLD) treatments and an enclosure were used to reduce mechanism housing noise. These were evaluated using sound power level measurements according to ISO 3744. The CLD treatments reduced the A-weighted sound power level by 3.1 dB in the 1 to 10 kHz one-third-octave bands. A panel-on-frame vibration mechanism enclosure using various types of panels further reduced the A-weighted sound power level from the CLD configuration in the 1 to 10 kHz one-third-octave bands by 3.7, 4.0, and 3.9 dB for aluminum, steel, and Dynalam panels, respectively. The combination yielded a 7 dB reduction from baseline in A-weighted sound power for the same frequency range.

Jan 1, 2010

By Karl A. Smith, Roger T. Johnson, David W. Johnson

Conflicts are common in the mining industry. Engineers are accustomed to addressing issues such as land use, air and water pollution, and health and safety. Although conflicts of interest are important in the industry, they do not have the impact on organizational decision making that controversy does. Controversy is a type of conflict, probably the most important type, for effective decision making and competent problem solving. It exists when one person's ideas, information, preference, choices, conclusions, theories, opinions, or perspectives are incompatible with another's and the two seek to reach an agreement (Johnson and Johnson, 1979). Interpersonal and intergroup controversy is prevalent in the day-to-day functioning of organizations. If constructively managed, this type of controversy has important implications for effective decision making and problem solving. Too few organizational members accept controversy, and almost none attempt to stimulate it. This is because too few of them understand controversy well enough to accept and use it effectively. Most organizational personnel lack the interpersonal skills needed to stimulate controversy and manage it effectively. Discussion of conflicting ideas may not be common in problem solving situations due to the fear and anxiety most people feel in conflict situations. Traditionally, organizations suppressed conflict. They believed it was avoidable, caused by management errors. Optimal organizational performance required its removal. Conflict, though, is inevitable. And optimal organizational performance requires a moderate level of conflict. Management should manage the level of conflict and its resolution, for optimal performance. The current view stresses the importance of controversy for learning. Confronting a person with a different point of view stimulates that person to gather more information to elaborate, justify, or provide rationale for their position. Controversy: Process and Outcomes The decision making process begins with participants categorizing and organizing current information and experiences so that a conclusion is derived. When participants present their conclusions to another group and realize their conclusions are being challenged, a state of internal conceptual conflict or uncertainty ensues. This uncertainty motivates the challenged group to actively search for more information, experiences, and a more adequate cognitive perspective and reasoning process to resolve the uncertainty. Participants will adapt their cognitive perspective and reasoning through understanding the perspective and reasoning of others to derive a new or reorganized conclusion. This process may be repeated several times before a decision is reached. The active search for additional information on the alternatives is also promoted, along with greater mastery and retention of information and a more accurate understanding of opposing viewpoints (perspective taking). Of the many positive outcomes of the use of controversy, the effect on higher level cognitive reasoning and processing is especially important in engineering decision making. Research has been done on expert-novice difference in medical diagnoses, physics problem solving, and geological exploration. It shows that preparation for verbal interaction and the actual verbal interaction with peers with differing view-points promotes the development of expertise. Constructive Controversy Conditions Some controversies among decision makers concerning their preferred solutions to a problem can be beneficial. But sometimes they are not. As with all types of conflict, the potential for either constructive or destructive outcomes is present. Whether the consequences are positive or negative depends on the controversy and the way it is managed. The conditions and procedures of controversy management that determine the outcome include: the goal structure within which the controversy occurs; the degree of heterogeneity of decision makers; the amount of relevant information distributed among decision makers; the ability of decision makers to disagree with each other without creating defensiveness; and the perspectivetaking skills of the decision makers. Goal structure: Two possible contexts for controversy are cooperative and competitive. A

Jan 3, 1985

By C. E. Brechtel

Bench cut-and-fill stopes with heights between 85 and 105 ft are being excavated in the lower levels of the B-NEATH Zone. Estimates of pillar strength and pillar loading indicated a high probability of pillar failure. Some changes in mining practice were made to minimize impacts of pillar failure and a rock mechanics instrumentation program was employed to monitor stability during mining of the first stopes. Limited pillar failure, in the form of destressing, was observed in the initial stopes; however, global stability during mining was good. Instrumentation data indicated that predictions of pillar strength and stress were quite close to field results.

Jan 1, 1989

By Elza Burch

Introduction The feeding to zero concept involves feeding 600 µm x 0 (28 mesh x 0) size raw coal to heavy media (magnetite) cyclones along with the +600 µm (+28 mesh) size coal. Traditional circuits employ desliming or removing the 600 µm x 0 (28 mesh x 0) size fraction and feeding the cyclones +600 µm (+28 mesh) size coal. The feeding to zero concept recirculates 600 µm x 0 (28 mesh x 0) fines in the circuit. At the same time, a portion of the fine material is continuously withdrawn and recovered. This, in turn, prevents a fines buildup. This concept eliminates desliming screens and secondary fines circuitry for recovery of 600 x 150 µm (28 mesh x 100 mesh) coal. The result is a very simple circuit. Feeding to zero at Island Creek Island Creek Corp. was the first involved with the new concept in 1976. The company needed a temporary plant for the 9.5 mm x 0 (0.4 in. x 0) raw coal at its Pond Fork mine, near Madison, WV, while a full-scale plant was being designed and built. At that time, the Childress Corp., of Beckley, WV, became interested in the feeding to zero concept. Island Creek awarded a contract to Childress to build a single cyclone modular plant, incorporating this feeding to zero concept. The plant was erected in three months. The Pond Fork modular plant proved successful in attaining the desired feed rate of about 63.5 t/h (70 stph), while maintaining good separating efficiencies and low magnetite consumption rates. The 9.5 mm x 150 µm (0.4 in. x 100 mesh) clean coal was recovered and the 150 µm x 0 (100 mesh x 0) size was disposed of to waste. The full-scale plant was completed about two years later and the Pond Fork modular plant was moved to Holden, WV. There, it was incorporated into the Holden 29 preparation plant as a separate circuit for cleaning -25 mm (-1 in.) coal. In 1976, a similar plant was installed in Virginia by another company. These two plants are believed to be the first two operational plants in the United States incorporating the feeding to zero concept. Island Creek subsequently contracted with Childress for an identical plant at the Coal Mountain operation in West Virginia. The plant operated for three years before the mine was closed. The unit was then moved to the Spurlock mine near Martin, KY where it continues to operate. The successful operation of the Pond Fork and Coal Mountain plants before and after relocation proved both the performance and moveability of this type of circuit when constructed in a modular fashion. Since the first two plants were built, Island Creek has incorporated the feeding to zero circuit in nine additional plants. A grand total of 33 cyclones have been installed using this concept. One is the Providence mine, near Providence. Providence preparation plant Island Creek contracted with J.O. Lively Corp. of Glen White, WV in July 1978 for the construction of the Providence preparation plant. The plant began operation in February 1979. The construction period was about halved by building the plant with modular design concepts. Prefabricated sections, floors, and sides were brought in as units and then bolted in place. The Providence plant has a good track record of processing coal at a feed rate of 454 kt/h (500 stph). Feed coal to the plant has an average ash content of about 18% and sulfur content of about 4.5%. It contains about 22% refuse. The coal product has an average ash content of about 8% and sulfur content is about 3%. Raw West Kentucky No. 9 seam coal is conveyed from a box cut in the Providence mine to a rotary breaker. The breaker is fitted with 74 mm-diam (3 in.-diam) opening breaker plates. Therefore, it is well suited for removing trash, roof bolts, wood, and pyritic balls that are common in Illinois Basin coal. The -75 mm (-3 in.) coal is conveyed from the rotary breaker to

Jan 8, 1987

By YU. F. Vasyuchkov, K. Vasioutchkov, B. M. Vorobjev

Introduction It is now believed that, even with the environmental protection measures now being taken, the further application of traditional coal-mining and electric power-generation technologies will inevitably cause further irreversible damage to the global ecosystem. Further improvements in conventional coal-mining technologies, both surface and underground, are expected to have only limited impacts on the economical, ecological and social aspects of coal mining. In countries with a developed coal industry, coal reserves with favorable conditions at shallow depths are rapidly being depleted. Therefore, in the future, more coal will be mined from deeper levels, resulting in higher operational costs and lower labor productivity. The solution to this problem is to be found in developing, promoting and implementing unconventional coal-mining and advanced clean-coal technologies. This paper presents an unconventional concept that has been suggested by the authors. The basic goal is to achieve coal-methane energy resource conservation and to remove barriers to energy efficiency through the adoption of integrated, ecologically clean, innovative technology. The following principles form the foundation of this concept: Energy resource conservation: This principle concerns the exploitation of actual and potential coal-methane reserves in the most effective way with the lowest possible losses and with the application of the most energy-efficient electric power-generation technology. Energy conversion: Energy conversion means the conversion of solid coal to synthetic fuel gas (in situ or in-cycle), the conversion of methane bounded within the coal matrix to free-flowing drained meth¬ane, the conversion of solid coal in situ to a coal/water mixture (slurry), and the conversion of these gas fuels into electric power. Technological and managerial integration: This prin¬ciple means an integration of coal-gas methane min¬ing operations and electric power generation into one commercial mine-to-product enterprise with electric power as the final product. Thus, coalbed methane drainage and coal gasification (both in situ and in-cycle) integrated with a combined cycle of electric power generation constitutes a highly integrated coal-gas methane energy-generation system. The system can be materialized in the form of a local integrated coal-gas electric power complex (LICGEPC). General features of the new concept The coal-gas-methane electricity concept is actually a synthesis of the following four technological components: Coalbed methane drainage. This technique and its utilization attained recognition after commercial operations were proven successful in the San Juan and Black Worriers coalfields in the United States. Worldwide, extensive field experiments and research-and-development activities are being carried out in the area of coalbed methane exploitation and utilization. Recently, coalbed methane drainage for power generation has been undergoing intensive research and development. At the Harworth Colliery in the United Kingdom, a combinedcycle power plant has been built that uses coalbed methane. The plant has an installed capacity of 15 MW Also, Germany, Australia, the CIS and China have conducted various experiments and industrial tests on the use of coalbed methane power generation. Underground coal gasification. Another unconventional technological approach is underground coal gasification (UCG). A number of semi-commercial, demonstration and pilot projects have been undertaken in Russia, the Ukraine, Uzbekistan, the United States, the United Kingdom, Italy and Belgium to demonstrate the technical and economical viability of coal gasification in situ. In Uzbekistan, the Angren coal-gasification station has been in full-scale commercial operation for two decades. The operation supplies a power plant with synthetic coal gas. Under sponsorship of the US Department of Energy's Morgantown Energy Technology Center, large-scale laboratory tests simulating coal gasification in situ were successfully completed by the

Jan 1, 1999

By J. D. Morgan

Demand for nonfuel minerals depends in large measure on economic activity, which rose in each quarter of 1985. However, despite 1.7 million new housing starts and a 7% increase in motor vehicle production, many domestic metal mining operations experienced continued difficulties as a result of import competition, greater use of newer engineered materials, emphasis on multi-unit housing, and downsizing of motor vehicles. Recognizing the continued difficulties of the domestic metal mining industry, many corporations made major efforts to retrench and rationalize - selling, closing, or spinning off less profitable operations, renegotiating labor contracts, and inviting increased participation by foreign firms. About 15% of US energy was imported in 1985. This included $52 billion worth of crude oil and refined products, adding significantly to the overall merchandise trade deficit of $149 billion. With the exception of a few large-bulk, low-value raw materials, most minerals move relatively freely in world trade. The strong dollar encouraged imports and made exporting more difficult US nonfuel minerals trade deficit totalled $17 billion. The US continued to rely on imports for many important strategic minerals in 1985 (see accompanying Table). Increased pressures for protection included major mineral products such as steel, ferroalloys, and copper. But President Reagan, in his Feb. 1986 "Economic Report to the Congress" stated: "Our international trade policy rests firmly on the foundation of free and open markets." He also stressed the need for fair trade and more open markets internationally. The National Critical Materials Council, created by law in the latter part of 1984, was activated in the latter part of 1985. Its first public hearing was held in January 1986. The Council is to review the nation's materials posture and advise the President on such matters. Compared with 1984, the value of US raw nonfuel mineral output rose 2%, to $24 billion. This supported the production of $244 billion worth of processed materials of mineral origin. Raw steel production - a major indicator of both material use and mineral production - fell 4% to 81 Mt (89 million st). Consequently, domestic iron ore production fell to 49 Mt (55 million st), about 97% pelletized. Iron ore imports fell 7% to 16 Mt (18 million st). Raw steelmaking capacity fell 4% to 117 Mt (129 million st). Pacts with 16 leading steel exporting nations have been negotiated in an effort to reduce import penetration of the domestic market. Domestic producers of bulk ferroalloys of chromium, manganese, and silicon operated at about 40% capacity. The US mined no manganese or chromium. Only a small quantity of ferronickel was produced from domestic laterite mining in Oregon. Molybdenum production increased slightly to 49 kt (54,000 st). Mine shipments of tungsten, another mineral tied to steel production, also fell slightly to 1.1 kt (1200 st) of contained metal. Even the domestic aluminum smelting industry suffered reverses as high stocks and low prices reduced production 16% to 3.5 Mt (3.8 million st). Similarly, imports of bauxite fell 7% and alumina 10%. Production of magnesium metal fell 6% to 136 kt (150,000 st), while titanium metal production remained unchanged at 22 kt (24,000 st). Copper mine production was unchanged at 1.1 Mt (1.2 million st). Copper refinery production fell slightly to 1.1 Mt (1.2 million st). Lead mine production rose 24% to 400 kt (440,000 st). Zinc mine output was down 10%, to 225 kt (250,000 st). Refined lead production increased 28%, to 510 kt (560,000 st). Primary slab zinc production fell 5% to 240 kt (260,000 st).

Jan 5, 1986

By R. W. Carn, D. Vincent

During the next 15 years, US coal production is expected to double, with the increased production evenly divided between the East and the West. Along with greater production, coal export markets should increase dramatically from East, West, and Gulf Coast ports. The annual overseas export capacity of US coal-loading terminals is expected to rise from 147.1 Mt (162.1 million st) in 1981 to a minimum of 278.1 Mt (306.6 million st) in 1985, according to the US Maritime Administration. Increased coal production and use will lead to more development of import and export terminals, a vital link in the coal transportation chain. With continually escalating capital costs and the competitive markets that the terminals will serve, a well designed and efficient terminal is necessary. This article begins a two-part series that presents concepts presently used in coal export terminal design. Part I looks at site selection factors and equipment needs, while Part II will examine environmental considerations in building a terminal as well as typical capital and operating costs. The world is nearing the end of the oil era. In a few years oil will not be available to sustain the growth rate and increasing standard of living we have known in our lifetime. The big question is what energy era are we moving into? With the decline of readily available oil reserves and rapidly increasing prices, many countries are trying to switch to alternate energy forms. While intensive efforts to find new oil reserves continue, alternate energy sources such as natural gas, coal, synthetic fuels, nuclear, hydroelectric, solar, and wind power are being developed. Recent indications are that coal is expected to bridge the energy gap over the next 25-30 years until the technology and economics of the alternate energy forms reach satisfactory levels. Use of coal for energy is receiving strong attention due to its long-term availability (200-300 years minimum), relative ease of development, and its low cost per unit of power produced. By the year 2000, it is expected that 25% of world energy supply will be met by direct coal combustion and possibly another 5-10% by synthetic fuel from coal. Coal's expanding share in the world energy market, along with an increase in coking coal requirements, will result in a large increase in the world's seaborne coal trade. Recent statistics and projections for the future are shown in Table 1. This phenomenal development rate includes increases in both coking and thermal coal requirements. Because of the rapid increase of seaborne coal trade during the last 10 years and the even greater projected increase of trade to 2000, various sectors of the coal industry are faced with enormous technical challenges and huge investments in equipment, land, transportation systems, and port facilities. Very large bulk terminals are under development throughout the world. Latest surveys indicate that there are about 30 new coal export and import terminals under consideration and at least 30 existing terminals have expansion programs planned or underway. With the high cost of borrowed capital and rapid inflation rates there is great emphasis on new planning and design techniques to minimize capital and operating costs of coal transportation systems. Terminals A total coal supply system can be considered to consist of one or more mines; a train, barge, truck, or other haulage system; an export terminal; a fleet of bulk carriers; a receiving terminal; and possibly, local inland distribution networks that include barges and railways. Terminals, though only a small link in the total transportation system, play a key role in overall system efficiency. At ports or inland distribution centers, terminals act as transportation links bringing trains, ships, barges, or trucks together for cargo transfer and temporary storage. A well-designed terminal can provide maximum independence between two modes of transportation and optimum freedom for intermodal interference. A terminal acts as a buffer between the two transportation modes by providing sufficient storage capacity so a ship need not wait for its cargo on, for example, a train-by-train basis, but can load immediately from the ready stock. Similarly, a train need not wait for a ship to unload its contents but can dump immediately into storage. A terminal also can be used to properly mix various types of coal to satisfy a buyer's requirements. Consider the relative value of various production and transport segments for a typical steam coal

Jan 6, 1983

By Lee W. Saperstein

The SME Research Council assists SME and its constituencies in establishing research directions that will benefit the mining industry and its professions. It also provides information about these directions to its membership, to government and to related industrial societies. The 1995 Research Forum, organized and chaired by George Luxbacher, was the second in a series of meetings organized to develop these directions. A copy of the full proceedings is available from SME for $12 plus postage and handling. The first research forum (Saperstein, L., 1993, "Technology for the Future, MINING ENGINEERING, Vol. 45, No 11, November, pp. 1382-85) invited mining industry representatives to discuss the unsolved technical problems that were keeping the industry from greater economic and environmental efficiency. The second forum asked academic researchers to discuss the same general topics from their perspective. It came as no surprise that, in general, the two sets of presenters tackled the same problems. There was no surprise when the academics spoke of the need for fundamental long-term research. What may have been surprising was the number of university people who spoke for near-term research that leads to measurable economic returns or savings. The closure of the US Bureau of Mines (USBM) has changed the objectives and attitudes of the SME Research Council. From being a point of liaison between SME and USBM - a conduit of items from each party to the other the council is now much more on its own. This isolation presents opportunities and hazards. The opportunities are exciting because the council could be the focus for mineral industry research policy if it were properly structured. The hazard is obvious - if there is no bureau, it could be argued, why maintain the council? Many people believe that SME should take the first course and become the beacon for research policy. More than ever, money is being spent on minerals industry research by the federal and state governments - particularly at the mineral-oriented land-grant universities - by industry and by consortia among these groups. SME could be at the hub of these programs. There is a general concern that industry is less able to maintain an economic edge by means of geologic discovery. According to Titley, there will be fewer major, new world-class discoveries except, possibly, at the continental and tectonic-plate margins. Consequently, economic advantage will go to those companies and nations that stay ahead technologically. Given the inevitable diffusion of technology, it can be concluded that technology development, underpinned by research, must be continuous to maintain profits. This is a change from earlier years when change would occur in relatively rare major steps that were interspersed with extended periods of technological equilibrium. Over the fiscal years 1994 to 1997, there has been a 24% cut in research spending by the Department of the Interior (figures from the American Association for the Advancement of Science). This is the largest budgeted percentage cut in research funding of any federal department. Even so, there is still a substantial amount of federal research funding expended in the mineral and extractive-energy industries. The US Geological Survey, Environmental Protection Agency, Departments of Defense and Energy and others expend substantial funds on minerals industry research. Industry - producers and manufacturers - is also spending large sums on research and research-like activities. This activity argues that there is a role for SME's Research Council. Providing focus Consortia. The closure of USBM has resulted in the migration of expertise to consulting firms and to other entreprenrutisl research entities. Many of these groups are creating ad hoc consortia among themselves, nearby universities and industrial partners. The Research Council is well placed to provide an open forum for these con¬sortia. Presentations of research results, as went on in the annual meetings of the Generic Mineral Technology Centers, can help to establish an. archive of results and an avoidance of duplication of research. A continuing sense of research directions can evolve. National Science Foundation. No discussion of consortia would be complete without mention. of the National Science Foundation's (NSF) programs for Industry/University Cooperative Research Centers (IUCRC) and Grant Opportunities for Academic Liaison with Industry (GOALI). NSF is aware of the gap in federal support of science and technology caused by USBM's closure.

Jan 1, 1997

By Patrick Corser, Mitch Usibelli

Introduction Coal mining in Alaska's interior, specifically in the Healy area, began as early as 1918 with the construction of the Alaska Railroad. Mining was originally limited to underground operations but has expanded to entirely surface operations. In 1943, the Usibelli Coal Mine was formed and started developing Alaska's first surface mine east of Suntrana (Usibelli Coal Miner, 1984). Production from the local coal deposits has steadily increased and, in 1978, surface mining of Poker Flats was initiated (Fig. 1). Currently, a 25-m3 (33-cu yd) walking dragline strips two coal seams, using an extended bench on the second pass. In addition, a fleet of trucks and shovels are used for coal removal and some limited overburden stripping. In 1984, a contract was signed between Usibelli Coal Mine and Sun Eel Shipping Co. in 1984. Since then, production has nearly doubled to more than 1.3 Mt/a (1.5 million stpy). This article will discuss geotechnical constraints on mining within the steeply dipping coal deposits that exist within the Poker Flats mining area. Specifically, the article will describe how the mining operation retriggered an historic landslide on the No. 5 coal seam (Fig. 2). And the article tells how a mine plan was developed that allowed the coal to be safely removed without inducing additional movement. Regional geology The coal-bearing group in the Nenana coal field is of Tertiary Age. It is overlain in some areas by several thousand feet of Tertiary gravels - the Nenana Gravels. In areas mined by surface methods, the Nenana Gravels have been eroded off, and up to 30 m (100 ft) of quaternary outwash gravels overlay the coal-bearing formations. The coal-bearing group is divided into five formations: Healy Creek, Sanctuary, Suntrana, Lignite, and Grubstake (Wahrhaftig, 1969). Lignite Creek lies on the north limb of a west plunging anticline. This has brought the Suntrana coal-hearing formations near enough to the surface to allow surface mining. Mining is presently in progress on the south side of Lignite Creek in the Poker Flats area. The coal-bearing formation is cut off to the south by a fault having perhaps several thousand feet of vertical displacement, with the upthrust side to the north. South of this fault, Nenana Gravels are exposed on the surface. The Suntrana Formation contain the minable reserves at Poker Flats. This formation is a repeated sequence of poorly consolidated pebbly sandstone near the bottom, grading through a silty fine sandstone to a footwall clay unit immediately below a coal seam cap. The footwall clays are high plasticity clays to silty clays. It has been reported that they contain 30% to 50% montmorillonite (Usibelli Coal Mine Inc., 1982). There are six coal seams in the Suntrana Formation, No. I (the lower seam) through No. 6. Only the top four seams are currently exposed. No. 3, No. 4, and No. 6 seams are the only mined seams. The No. 5 seam is very thin or not present. Portions of the undisturbed Suntrana Formation are overlain by up to 15 m (50 ft) of Quaternary outwash gravels or recent landslide rubble. The surface is overlain by a very thin layer of muskeg and isolated areas of permafrost. In many areas, the outwash gravels are found immediately below the surface muskeg. Numerous landslides have been documented along the north facing slopes of Lignite Creek (US Geological Survey, 1970, and Wahrhaftig, 1958). These appear to be surficial solifluction or skin flow types of landslides. In addition, deep-seated structurally controlled slides are also evident on both the north and south sides of Lignite Creek. Structural features Premining aerial photographs (Fig. 3) of the Lignite Creek slopes in the Poker Flats area indicate substantial evidence of deep-seated landsliding. The landslides noted in Fig. 3 are both inside and outside of the current mining area. Surface mapping and geologic exploration indicate that the coal seams are dipping out of the slopes within the noted slide areas. It is suspected that, historically, these landslides were triggered by undercutting of the toe of the slopes by Lignite Creek. And sliding it thought to have taken place on one or more of the clay beds underlying the coal seams (Golder, 1985). The slide areas are characterized by semicircular head scarps and slumped topography. Based on the premining photographs, these slides do not appear to have been recently active. However, they are expected to be in a state of only marginal stability. Extensive coal exploration indicates that the primary structural feature within the

Jan 1, 1989

By V 9. 0 / 300 dpi

Papua New Guinea (PNG) stretches from the equator to Latitude 12° South and from Indonesia's Irian Jaya Province in the west to the Solomon Islands in the east (Figure 1). The population totals 3.5 million people who are mostly concentrated in highland valleys on the main island and around the coast. This paper outlines the history of mining, describes the natural, cultural and regulatory setting of mineral discoveries and highlights, by example, some of the more idiosyncratic environ-mental aspects of mining developments in PNG. It concludes with remarks on the progress made in the fifteen years since environmental matters entered the agenda for the establishment of a new mine in PNG.

Jan 1, 1988

By K. S. Venkataraman

The physical properties of clay-water systems depend on the complicated system of forces between the clay particles themselves, and between the clay particles and the ions in the liquid phase. The kind and distribution of ions in, on, and between the clay particles and the size and the shape of the particles are the basic factors determining the macroscopic behavior of clay-water systems. Understanding the system requires a knowledge of the nature of the clay particles, their size, structure, composition, and surface properties, and of the manner in which they interact with ions [and molecules] in the surrounding liquid [or other medium]. The validity of Professor Brindley's words (Brindley, 1958), written three decades ago in the context of making pottery, whitewares, and electrical porcelains, transcends time, and the basic message is perhaps all the more important in the considerably expanded use of ceramics for structural, thermal, tribological, electronic, and other applications. Silicon carbide, silicon nitride, and sialons have been studied in the last two decades for high- temperature structural and tribological applications, particularly for using in internal combustion engines. Titanates, zirconates and niobates of barium, strontium and lead, have high dielectric constants, and are extensively used in the formulations for making capacitors. Hexagonal ferrites (molecular formula MO.6Fe2O3) are in use for making permanent magnets for fabricating miniature motors, and for assembling loud speakers, particle accelerators etc. Cubic ferrites such as magnesium-zinc ferrite and nickel-zinc ferrite are used as transformer cores, and for other high-frequency applications. In this context, Richerson's recent book (Richerson, 1984) on the general scope of traditional and technical ceramics is a good starting point for an overview of contemporary ceramics technology. Glasses are a whole class of amorphous materials used widely as sintering aids, and for making glass-bonded ceramics and glass-ceramic composites. Composites are yet another burgeoning field where two or more particulate components are used for improving the performance of ceramics. For all these applications, the inorganic starting materials are almost always submicron and near-micron powders. Understanding the powders' physicochemical properties, and their surface chemical interactions with the surrounding liquid/gaseous medium is-necessary for making reliable ceramic parts at competitive prices. Even though ceramics science and engineering has attained its separate identity in universities and the industry, ceramists themselves would concede that ceramics science is a cross-disciplinary field, having incorporated and assimilated within itself many principles from several apparently disjointed disciplines. Principles of material science, graduate-level physics and chemistry, polymer science, surface and colloid chemistry, transport phenomena, particle technology, unit operations commonly used in chemical engineering and mineral processing, and statistics and applied mathematics are integral part of any ceramics curriculum in universities. Added to this is the fact that all bench-scale successes in making ceramic parts are to be scaled-up for larger throughput operations. Understanding and applying process engineering principles of comminution, classification, drying, calcination, etc. then becomes essential. CERAMIC FORMING: Despite the diversity of the materials and processes, conceptually, the steps involved in making ceramic parts have remained the same over several decades: The different components for making the pan (usually one or more powders plus other forming and sintering additives) are proportioned and mixed thoroughly, and the well-mixed formulations are consolidated into desirable shapes known as "green bodies." Usually binders such as wax, clay, organic polymers and surfactants, whether dispersed or dissolved in a suitable liquid are used during mixing the batch for giving strength for the green bodies. In the dried green state, the inorganic powders typically occupy only 55 to 60% of the bulk volume of the body, depending on the particle size distributions of the powders and the forming history, with mostly inter- particle voids accounting for the rest of the void volume. SINTERING: The formed bodies are then fired in high- temperatures kilns/furnaces during which the parts are exposed to a predetermined temperature profile, and "soaked" for a certain duration at the final high temperatures, typically between 1200 K and 1900 K, and then cooled to room temperature. The gaseous atmosphere in the furnace is controlled (oxidizing, reducing, or inert) when necessary. During the initial stages of firing, volatile liquids evaporate, and during the intermediate temperatures between 400 and 600 K, the the organic polymeric additives pyrolize and oxidize into water vapor, CO, C02, and other gases. At still high temperature, the glasses, when present, soften, and simultaneously, the ceramic particles rearrange into a network of grains with definite grain boundaries so as to reduce the total interfacial free

Jan 1, 1990

By L. Micale

In May of 1986, the Arizona Legislature passed comprehensive environ-mental legislation called the Environmental Quality Act (the Act). The Act focuses on ground water protection and addresses drinking water quality, aquifer protection standards, requirements to apply technology to reduce discharges, and a state Superfund program.

Jan 1, 1988