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By H. S. Duzgun, N. Demirel

Estimating productivity of a walking dragline is of paramount concern to mining engineers and mine planners. Risk based evaluation of the dragline productivity is a valuable tool to estimate the dragline’s long-term availability, to develop preventive maintenance plans and to make future projections about the dragline’s performance. This paper aims to provide mining professionals with an overview of risk assessment methodology for productivity of two walking draglines, Page 736 and Marion 7820, which have been operating in the Tunçbilek openpit coal mine of Turkish Coal Enterprises (TKI) in Turkey. The study encompasses three main stages: (i) acquiring of monthly maintenance records, operating hours, mechanical and electrical failure hours between 1998 and 2009; (ii) reliability modeling using mean time between failure data and (iii) determining hazard rate and consequences to compute risk associated with dragline productivity. The results showed that that Page 736 (15.29 m3) seemed to be more reliable and less likely to fail when compared with Marion 7820 (30.58 m3). The operating hours without failure range from 41 to 51 hours with 50% reliability.

Jan 1, 2011

By C. L. Karr

Establishing suitable control of pH, a requirement in a number of mineral and chemical industries, poses a difficult problem because of inherent nonlinearities and frequently changing process dynamics. Researchers at the U.S. Bureau of Mines have developed a technique for effectively controlling such systems. This technique successfully combines the process control capabilities of fuzzy logic and the search capabilities of genetic algorithms. Fuzzy logic offers an effective mechanism for handling nonlinearities, while genetic algorithms can provide fuzzy logic controllers with real-time adaptive capabilities. This Bureau-developed technique is applied to a laboratory acid-base neutralization experiment. Nonlinearities in the laboratory system are associated with the logarithmic pH scale and the changing process dynamics are due to alterations in pH and buffering capacity input solutions. Results indicate fuzzy logic controllers augmented with genetic algorithms offer a powerful alternative to conventional process control techniques in such nonlinear, rapidly changing systems.

Jan 1, 1992

By Robert H. Merrill

7.1-STABILITY OF SLOPES IN SOIL AND ROCK ROBERT H. MERRILL 7.1.1-DESIGN ANALYSIS APPROACHES The analyses of slopes in soil or rock can be made through application of soil- or rock-mechanics principles. In most cases, the material in the slope wall can easily be identified as either a soil or a rock. However, there will be instances where, because of unique characteristics, the soil may behave as a rock structure, or vice versa. By necessity, these unique cases must be identified through experience or critical observation by the engineer, because there are no definitive rules clearly establishing the differences. The most important step in a solution to a slope problem is to define it. Normally, once the problem is identified, a solution usually can be found or a reasonable estimate obtained. The design analysis of a slope wall implies an evaluation of the stresses or forces in the wall, and of the ability of the material in the wall to withstand them. Therefore, the factors influencing a design analysis can be divided into two categories: those which influence stresses, and those which influence the ability of the wall to withstand stress. For simplification, the latter is termed the strength of the soil or rock. Perhaps the basic difference between analyses for soils and those for rock is in the identification of the failure surface. Soils generally do not have an identifiable failure plane. However, some soil layers in a slope wall may have different strengths. A soil slope wall may consist of a thin layer of topsoil overlying a thick, uniform clay, or a topsoil over a gravel or other materials. Therefore, the soil generally does not have a potential plane of weakness that can be identified through observation. On the other hand, rocks normally contain planes of weakness in the form of fractures, faults, joints, bedding planes or other discontinuities weaker than the intact rock, which can be found through observation and/or tests upon rock samples. If the failure surface cannot be identified, the principles of soil mechanics should apply because, in soil mechanics, the failure surface usually is assumed. If it can be identified, then the principles of rock mechanics should apply. 7.1.2-ANALYSES OF STRESSES OR FORCES IN SLOPES All existing methods of soil-slope analysis are based upon interpetations of the Coulomb and Coulomb-Navier failure criteria, commonly termed the total-stress 2nd the effective-stress criteria (Sec. 6.1). The total-stress criterion may be illustrated by the diagram in Fig. 7-lA, which relates the total stress, S, to the cohesion, c: the normal stress, u, and the angle of internal friction, 9, by the expression

Jan 1, 1973

By K. V. Raj, A. Miller

"Workers at mineral processing facilities are often exposed to high levels of dust generated when ores are processed. Crushing, grinding, screening, and other processes generate large quantities of dust, which can exceed the threshold VALUES (prescribed by the Mine Safety and Health Administration (MSHA). Many ores contain quartz (silica), which has been known to cause serious health problems in workers over time. Given the structure of mineral processing plants, the airflow regime is not coherent inside the building, which may lead to multiple recirculation zones. These recirculation zones can trap dust, and concentrations of dust can then rise over time. Therefore, there is a need to understand the airflow phenomenon that occur inside of mineral processing facilities and how these occurrences interact with the dust generation processes to identify zones of potentially high dust concentration. Computational fluid dynamics (CFD) modeling can give a better understanding of the airflow and help recommend designs and methods to mitigate the high dust concentrations in a mineral processing plant. This paper presents the CFD modeling of airflow inside of a mill building to demonstrate airflow patterns that will affect the generation and subsequent dispersion of dust due to crushing, grinding, and other activities. This study was conducted by researchers from the National Institute for Occupational Safety and Health (NIOSH). INTRODUCTION In a mineral processing facility, minerals go through various mechanical processes in order to reduce their size for separation of economic minerals from gangue minerals to produce a final marketable product. This research, conducted by the National Institute for Occupational Safety and Health (NIOSH), focuses on ore mills in metal and nonmetal mining (MNM) operations, but the applicability of the approach will be valid for any large structure where workers are exposed to airborne contaminants. The processes of crushing, grinding, cleaning, drying, and product sizing in these facilities generate a large amount of dust, creating hazardous conditions for the workers in these facilities. This is highlighted by the fact that MSHA sampling data for the years 1997–2012 indicate that 12.3% and 15.9% of the gathered samples were over 100 µg/m3 for silica for metal and nonmetal mills, respectively [1]. Mineral processing operations typically use some type of engineering control to address their most significant dust sources. Engineering controls include such approaches as bag-house-type dust collectors, scrubbers, and electrostatic precipitation [2]."

Jan 1, 2018

By L. Lichty, R Bhappu, R. Rowan, G. Ramadorai

Treatment of refractory gold ores containing arsenic have always presented a major problem in their processing to recover the contained precious metal values. The major difficulties are concerned with lower recoveries, production of hazardous fumes, effluents and residues. Because of'these arsenic related problems, many otherwise economically attractive precious metal deposits and dumps all over the world are not exploited. In recent years, treatment processee for refractory gold ores and concentrates have been explored and a few commercial operations employing roasting or pressure leaching have resulted. Roasting has limitations due to environmental constraints related to off gases. Pressure leaching involving high temperatures (180% to 200%) and pressures (400 psi) is accompanied by high capital and operating costs. An alternate route to roasting for treating pyrite and arsenopyrite ores and concentrates ia the "lime-oxygen hydromet" process carried out at a moderate temperature (100%) and pressure (100 psi). A simplified process for treating such arsenic containing ores and concentrates utilizing low temperature and pressure oxidation is presented. This low cost treatment with compressed air and lime renders arsenic as an inert component in the residue, meeting all the requirements of the EPA Toxicity Test. The precious metal values are then extracted from the autoclaved residue by standard cyanidation. This paper discusses this new development.

Jan 1, 1990

By Gabino Preciado, Louis Sandbak

Corrosion has long been identified as a potential risk to the long-term ground support stability due to degradation of internal ground support elements such as rock bolts but also to surface support from mesh, straps, bolt plates, and ancillary support of utilities such as hangers. The emphasis is to understand the corrosion mechanisms on the primary ground support elements and any supplemental steel or arch sets. The water and chemical processes from oxidation(rust), stress corrosion cracking, and even the electrical charge created during these reactions contribute to the corrosion of the steel support elements. The main goals are to mitigate the effects of corrosion and to be able to predict those areas of high water or high sulphide for potential rehab maps. It is also essential to identify and classify the visible corrosion as part of damage mapping and provide bolt testing to those areas of suspected internal damage from corrosion. This is important to get an estimate of the support longevity or expected life before rehab to minimize the overall cost of the operation.

Feb 1, 2024

By G. T. Lineberry, W. J. Wiehagen

A paradigm shift As market economists, mine managers are interested in "staying in business" and even "prospering." Bottom-line results are the "order of the day." Concern for bottom-line results can invoke questions such as how much was produced, at what cost, and was anyone injured? While these questions will always carry everyday emphasis at the mine, they are fundamentally lacking in that they often appear, especially to lower levels of management and to the production worker, as pre-eminent concerns. Driven by market economics, many organizations have decentralized, outsourced, downsized, restructured and formed new coalitions. Investments in new technology and a concentration on productivity have been an essential part of these changes, contributing to improvements in both safety and efficiency. A reason for (and, perhaps a result of) these improvements has been the development of a highly experienced and flexible work force. This situation presents an interesting opportunity to modify a few paradigms about work life in general, and perhaps a few paradigms about how we invest in the miner, in particular. Studying these issues now night offer some interesting opportunities for the Future, as the foundations for the next generation of mine workers are laid. With the average "experienced" U.S. miner five to fifteen years from retirement, perhaps a key determinant of future success in the world market might be how well we make the transition from today's work force to the work force of tomorrow. We can ill afford to wait a few more years to tap into the special knowledge residing within a veteran mining work Force. The Work Crew Performance Model (WCPM) is one approach to defining, capturing and transferring this expertise. The WCPM suggests a paradigm shift, moving from a focus on products (quantity) to a focus on the process (quality). It also involves a slight change in the process -- a different way to think and work. Of great importance, it entails a belief and a commitment to people within the organization; a commitment to collect simple (but interesting) data; exploration for insightful ways to plot and integrate that data; and finally the search for creative methods to reinvest that knowledge back into the organization, that is, back into the work force. As a way of thinking, the WCPM subordinates information about how much is produced daily or how many were injured over a year's time to concern and detail for how the individual's and the work crew's performance contribute toward meeting organizational goals. Drawing upon the expertise within members of that work crew to address and solve operational problems is one approach for meeting organizational goals. This everyday focus on how we work is hypothesized by the WCPM to make the difference between a good section supervisor and the average one; an exemplar continuous-miner operator and the run-of-the-mill one; a mining crew that produces consistently high quantities, but, inadvertently, degrades the production of other units. The WCPM permits objective and reliable performance data to be collected. This data then can be used to define variability within tasks of work crew members; to relate observed variability to a cost consequence; and to more meaningfully analyze performance through the integration of traditional analytical tools, such as the production simulator, CONSIM, with a recommended behavioral approach, the WCPM. Basis for engineering test Most equipment selections and purchases involve a field trial test of the system. Technology is routinely bench tested at the manufacturer's facility, government agencies and the mine site. The WCPM suggests a similar, but more practical, method for testing the performance of a work system -a test for how technology is used (by people) at the work site. It implies learning from veteran mining personnel that have gone well "beyond the book." This approach to learning and to integrating training with everyday work life can help answer questions such as: What constitutes desirable perfor¬mance as, for examples, a shuttle-car operator, a miner operator or a bulldozer operator; what characterizes exem¬plary performance within the context of the work system, the technology and the work crew; how can investments in the worker he linked to measurable results within the organiza¬tion? This paper explores these questions and makes recom¬mendations for enhancing the cost-linkages between invest¬ments in people and the mine's monthly cost sheets.

Jan 1, 1996

By Steve Karl

Introduction US steel production dropped 5% in 1985 to 79 Mt (87 million st). US operators are producing at only about 65% of capacity. More than 600 steelmaking facilities have closed in just 10 years. And McDonalds Corp. now employs more people than the entire US steel industry's 200,000. Not gloomy enough? Well, the North American iron ore industry can expect more plant closures and capacity reductions in the coming years. And don't count on the Federal government's voluntary restraint agreements with foreign steel producers to bail out the industry. In 1985, the first full year of the restraint agreements program, steel imports were more than 25% of domestic consumption, well above the 18.5% target. That's the grim truth, according to M. A. Hanna's Robert F. Anderson. Hanna's chairman was speaking to a group of iron ore, taconite, and steel industry executives at the Minnesota Section AIME meeting in Duluth in January. Despite those depressing facts, Anderson said he believes the domestic iron ore and steel industries can survive, although they will both be shadows of their former selves. But, he is giving them five years to make the necessary adjustments or both will die. Major steel producers during the last four years have added about $7 billion in losses to their books, he said. In Minnesota's Iron Range, employment in iron ore and taconite has gone from 14,000 10 years ago to less than half that today. Anderson explained that steel producers have more capacity today that more than meets their demand for iron ore. This places great pressure on iron ore producers to restructure to survive. Hanna, for example, has been forced to close or divest its iron ore interests in Missouri, Michigan, Canada, and Minnesota since 1980. The latest casualty was the company's Butler taconite project in Minnesota. "In just five years we've reduced ownership of active pellet capacity by 80%," he said. Technological ironies Improved technology is one cause of the industry's woes, Anderson said. While these improvements are welcome in terms of remaining competitive, the irony is that some of these technological improvements are coming at the expense of the iron and steel industries. There is a growing demand for lighter and less expensive substitutes for steel. Automobiles contain about 318 kg (700 lbs) less steel than they did 10 years ago. And, Anderson said Ford Motor Co. has indicated it plans to reduce steel usage an average of 50 kg (112 lbs) per car in the next few years. One leading steel analyst has predicted that steel usage in cars will fall another 40% in the coming years. Improved steelmaking technology has also decreased raw steel production. Continuous casting is more efficient than traditional forms of steelmaking, Anderson said. Continuous casting accounted for about 43% of steel production in the US last year, compared to 9% a decade earlier. And, Japan and Korea are producing more

Jan 3, 1986

By S. L. Bessinger

In the design and specification of a ventilation system for an underground mine, it is necessary to make reasonably accurate estimates of the pressure losses in the various airways of the mine. These estimates can be made with little difficulty for open airways with simple geometric cross-sections, such as those cut by continuous miners or tunnel-boring machines. The situation is much different on a longwall face, where the airway's complex geometric cross-section and the presence in the airway of obstructing equipment having a variety of shapes make it difficult, if not impossible, to estimate pressure loss using traditional methods of calculation. Headlosses in mine entries are calculated using Atkinson's Equation (1). [H = (English) H = (SI) (1)] where H = pressure ,loss, in. of H20 (Pa) K = friction factor, lbf min2/ft"4(Kg/m3) P = perimeter, ft. (m) L = airway length, ft (m) Q = airflow quantity, ft3/min (m3/sec) A = flow cross sectional area, ft2 (m2)

Jan 1, 1987

By Ethan Steward, Kyle Perry

The study investigates the effects of high-velocity impacts of common mine materials on a reinforced mine seal rated to 120 psi. It found that materials propelled during an underground explosion could generate enough stress to crack or damage seals, even with little visible damage. This highlights the need for careful evaluation of mine seals after any impact or high-pressure event.

Aug 1, 2023

By F. S. Knoll

The high tension process which separates materials based on relative differences in surface conductivity has been very successful in recovering non-ferrous metals from municipal waste. Aluminum is by far the largest constitutent of the total non-ferrous metal fraction; accounting for >95% in most localities. Wire and insulation mixtures from industrial wastes have been treated commercially for several years by a high tension process initially developed for use in the iron ore industry. The wire and insulation application was a forerunner of municipal waste dry treatment technology. In the past eighteen months the rotating-drum-type electrostatic separator has undergone extensive testing and development in order that the process might be efficiently adapted to the recovery of aluminum from municipal waste.

Jan 1, 1974

By Alejandro Sanz, Juan Luis Magro, David Mazeyrie

The Hampton Roads Bridge-Tunnel Expansion Project (HRBT), initiated by the Virginia Department of Transportation (VDOT), will add two new 1.5-mile TBM bored tunnels to the two existing immersed-tube tunnels between artificial islands, part of the connection between Norfolk and Hampton under the Hampton Roads Harbor in Virginia, USA. The new bored tunnels will be built by Hampton Roads Connector Partners (HRCP), a joint venture of Dragados USA, Vinci Construction, Flatiron Constructors and Dodin Campenon Bernard. This paper covers technical discussions that led HRCP to select a Variable Density TBM to address the challenges of this tunnel project, including but not limited to (i) the diameter of the bore: a 46 feet (14.04 m) diameter machine that constitutes the second-largest TBM ever used in the United States; (ii) shallow ground-cover under the water table; (iii) challenging and varying geology along the alignment, with mixed-face conditions and different types of ground modification zones; and (iv) the high TBM operating pressures required—all these and other challenges in a sensitive marine environment.

Jun 13, 2021

By M. A. Cornachione

The west central upper Peninsula of Michigan contains a large resource of graphitic slate. The slate has potential industrial use as a substitute for shale currently used in the production of portland cement. Some of the unweathered slate, however, has a high concentration of pyritic sulfur which can create emission problems when processed in a kiln. A low cost method to reduce the sulfur content of the slate through the optimization of pyrite oxidation in a bio-heap leaching operation was investigated.

Jan 1, 1992

By A. D. S. Gillies, Hsin Wei Wu

An evaluation of the use of air cooling power as an index of the thermal environment is discussed. A body temperature prediction -. model based on body temperature tests, a concept linked to a maximum safe body temperature and the predicted fourth hour body temperature which depends on the rate of heat accumulation (heat storage) within the body has been developed and tested. This has led to the conceptual development of a personal response heat stress meter calibrated to the physiology of the personnel within the workplace. The proposed heat stress meter will be able to measure workplace environmental parameters such as air temperature, humidity and air velocity and the user can either select or manually enter other heat stress parameters such as work rate, clothing type and subject's personal response to heat. With a built-in computer program, the meter will calculate the ACP of the workplace, the fourth hour body core temperature expected and the maximum safe working time allowed for a pre- defined limiting body temperature. A brief description of the work required for developing the meter is included. The potential benefits of such instrument to the mining industry are also evaluated.

Jan 1, 1997

By D. J. Torpy

With copper at its host depressed price in several years, producers are looking at every opportunity to cut costs in order to continue operating. Some of the measures that have been applied by different companies include reduction in manpower, high grading, and in some cases partial shutdowns. The most beneficial cost cutting measure implemented by Southern Peru Copper Corporation was to steepen the slope of the final pit limit from a conservative 37 degrees to an average of 48 degrees. By doing so, substantial cash outlays were saved. Southern Peru Copper Corporation (SPCC) operates two open pit copper mines and concentrators in the southern part of Peru, about 150 kilometers from the Chilean bordar. The Toquepala Mine went into production in 1960 and the Cuajone Mine in 1976. Both mines use shovel, truck and train operations. The trains, which haul ore to the crusher or waste to the dumps, are loaded either directly by shovels or by a transfer system. The Toquepala Concentrator treats an average of 43,000 tons per day and the Cuajone Concentrator an average of 55,000 tons per day. Concentrates are shipped via a 200 kilometer railroad to the port city of Ilo where the SPCC smelter is located. The annual production in the smelter from both mines is 290,000 tons of blister copper.

Jan 1, 1987

By Paul H. Muller

The configuration of remote seal DP cells for specific gravity measurement is described and the calculations for calibration are presented. The error induced by ambient temperature change is investigated as it relates to capillary dynamics and electronic considerations. Instrument specifications are discussed in the light of accuracy requirements and the calculation of error vs. ambient temperature is described.

Jan 1, 1984

By W. H. Strickland

The research reported here characterizes ultrasonic ranging sensors for autonomous navigation on underground mine mobile equipment. Because ultrasonic rangers are inexpensive, have no moving parts, have no lenses to clean, are small and unobtrusive, and can measure distances in dusty environments, they are especially sui ted to underground mi ne environments. The investigation began with laboratory tests of field of view, angle of incidence, intersensor variation, and ranging accuracy of individual rangers and a ring array of 24 sensors. The results showed the sensors have good accuracy and low variability. Additional experiments at AHAX' s Henderson mine Showed the sensors could accurately and reliably measure rib features, convex and concave corners, and drift intersections. The results showed that when used and analyzed properly, the sensor data may be used reliably for underground mobile equipment navigation.

Jan 1, 1990

By Sam M. Pickering

Most high, purity silica is produced from crystalline quartz-generally from sand. However, there is a small area of southern Illinois where a porous, friable white chert rock is found which is very different in physical form from quartz sand. This microcrystalline material, commonly referred to as tripoli, is more easily ground to micron sizes than sand. Although of similar Moh's hardness, microcrystalline tripoli is less abrasive than either ground quartz sand or many synthetic abrasives. Location The southwestern corner of Illinois is underlain by extensive deposits of very porous chert; in some places the material is quite white. Two companies - Illinois Minerals Co. and Tammsco, Inc. - mine and process this white material. The Illinois Minerals plant is located at Elco, and the Tammsco plant is in Tamms, Illinois. Both companies mine from various locations within a ten mile truck haul of their plants. Production from this district has been continuous since at least 1915. Malvern Minerals Company mines and processes a generally similar microcrystalline, friable novaculite near Hot Springs, Arkansas.

Jan 1, 1985

By A. B. Holland-Batt

Following a relatively static period in the 1960s and 1970s when incremental development rather than innovation was the norm for gravity separation, the last 15 years has seen a number of new developments in this area. The paper briefly reviews the traditional gravity separation techniques and then examines the newer developments such as centrifugal separators. Particular emphasis has been placed on novel devices or improvements that offer either better control or improved performance.

Jan 1, 1998

By C. R. Montgomery

Coal companies in order to supply their customers En the metallurgical market, both home and abroad, must be able to control their production in order to meet carbonization specifications over and above those of the proximate analyses which has been the prime consideration of purchases in the past. It is the purpose of this paper to review in brief some of the tests used and give data to show the application of such as it applies to the customers needs. It is now recognized that coal is not homogeneous in any of its properties and an amazing fact is that it has been used for so long a time as the principal raw material for the manufacturing of coke without more emphasis having been placed on the variation between coals; yes, even from coals in the same seam at different geographical locations, Recently Kuchta and Clendenin pointed this fact out In a study of the(1) carbonizing behavior as related to chemical and plastic properties of Alabama medium volatile coal.

Jan 1, 1962