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By H. Cho

A study was undertaken to investigate the liberation behavior of coal macerals through size reduction and density separation. It was seen that the liberation of coal organic components could be achieved by size reduction, allowing selective separation of coal organic components. However, the degree of liberation is dependent on the history of coal: the extent of liberation decreased when the size of the primogeniture coal decreased. The liberation of coal macerals was analyzed by examining the Liberation Index. It was seen that although comminution produced fine particles enriched in inertinite (primarily fusinite and semifusinitie), these particles were less liberated than the coarser particles. However, the liberation of macerals increased when all the feed was ground to a finer size.

Jan 1, 1996

BP Minerals America (BPMA) has completed its $400 million modernization of Kennecott Utah Copper's Bingham Canyon mine. Modernized facilities include the in-pit crusher, conveyor, ore storage area, concentrator, ore pipe-line, and tailings pipeline. With modernization, Kennecott will achieve substantial cost reductions. Bingham Canyon is now one of the lowest cost copper producers in the world. And the mine will continue to provide jobs and income in Utah for another 30 years or more. The Modernization Project began in February 1986. The work took 33 months. In late 1987, the construction force peaked at 1100 workers. Kennecott Utah Copper now employs a permanent work force of 2100 employees. Less equipment and more efficiency The modernization work has increased the scale of the facilities that transport and process copper ore. A large, continuous transport system has replaced multiple haulage units. Fewer but larger pieces of equipment have replaced many crushing, grinding, and flotation units. The result is less maintenance, fewer employees, and improved metal recoveries. About one-third of the $400 million modernization project is directed at improving ore movement by eliminating rail transport. The new concentrator accounts for the remaining two-thirds of the modernization investment. The modernized plant was started up in stages. In February, ore was fed to the crusher. By the end of March, the three grinding lines were operating and the flotation circuit was producing copper concentrate. In July, the design through-put rate of 70 kt/d (77,000 stpd) was reached. October saw the achievement of targeted metal recoveries that corresponded to the fully modernized operation. It is estimated that Bingham Canyon will annually produce 181 kt (200,000 st) of refined copper, 9.3 t (300,000 oz) of gold, 71 t (2.3 million oz) of silver, and 5.4 kt (12 million lb) of molybdenite. Current Bingham Canyon production is about 97 kt/d (107,000 stpd) and a similar amount of overburden. Some 70 kt/d (77,000 stpd) of ore are processed through the in-pit crusher and 27 kt/d (30,000 stpd) of ore are transported by rail. The Bingham Canyon mine has yielded more than 11 Mt (12 million st) of refined copper. In 1863, precious metals - silver-bearing lead - were first discovered in Bingham Canyon. What was once a mountain is now a huge open pit. In fact, the mine is the world's largest man made excavation. The pit is some 4 km (2.5 miles) wide and 0.8 km (0.5 miles) deep. Since the pit began operating in 1906, more than 4.5 Gt (5 billion st) of material have been removed. Modernized facilities Electric 21 m3 (27 cu yd) or 23 m3 (30 cu yd) shovels are used to load the haulage trucks. Both 154 t (170 st) and 181 t (200 st) trucks are used to haul the ore to a mobile, in-pit crusher. The crusher replaces three crushers located at the old concentrators. There are two dumping locations at the new crusher, which can handle two trucks a minute. The 1.5 x 2.7 m (60 x 109 in.), 745 kW (1000 hp) Allis-Chalmers gyratory crusher reduces the ore to 254 mm (10 in.) size or less and delivers it to the conveyor. The crusher and conveyor systems are capable of handling 9 kt/h (10,000 stph) of ore.

Jan 11, 1988

By Mustafa Akser

Dwindling economic deposits of rutile (TiO2) prompted research on recovering it from secondary sources. One such resource is in Southwestern Turkey feldspar mining rejects that contain 5%-6% TiO2 mostly rutile. Previous studies could only upgrade the TiO2 to 36% TiO2 grade, claiming that the leftover flotation reagents on the surfaces of rutile and host minerals detrimentally affected upgrading of the rutile. As a potential remedy to this concern, a laboratory sample (from an operating feldspar mine in Milas, Turkey) was first caustic scrubbed, then air calcined at 400°C to evaporate the oily reagents. Subsequent physical separation of rutile included wet screening, gravity, magnetic, and electrostatic separation technologies. Such processes indeed improved the grade of the rutile concentrate up to 83 % TiO2 Low recovery of the TiO2 (<20%), was attributed to lack of full liberation of rutile, even at 125x44 micron range; interference with impurity minerals such as sphene and zircon; and simply the process inefficiency in upgrading the fine grains through conventional separation technologies for heavy minerals.

Jan 1, 1999

This paper presents the development of a knowledge based integrated decision support system (E.X.I.S) for the extractive industries to provide information concerning the environmental impact of extractive operations on land quality, surface and ground waters, and the best solutions for the rehabilitation/revegetation of the waste disposal areas to the relevant target groups (extractive industries, regional authorities, national authorities, research institutes, public). GIS was integrated with the decision-making models for the rehabilitation and revegetation of mine spoil. The system design involves several steps including site selection ? mine type identification ? waste identification ? selection of rehabilitation (revegetation or other methods). The knowledge based model consists of two integral parts: the model base, in which the input data are processed and classified using special fuzzy algorithms and criteria and the knowledge model, which hosts the various decision algorithms concerning evaluation of vegetation covers, selection of trees and plant species, selection of rehabilitation and revegetation schemes and also economic analysis for each option. The system input will include parameters on site characteristics (climate, topography, geology, hydrology etc), waste type and properties (physical-geotechnical and geochemical data) as well as environmental parameters of the existing waste disposal area. Based on the values of the above parameters and the characteristics of the rehabilitation technologies developed worldwide, the system, using IF-THEN rules will define a list of appropriate techniques for the rehabilitation of the examined waste. Then, the model will involve the application of multi-criteria analysis (MCA), i.e. a structured system for ranking alternatives and making selections and decisions. Each technique shall be judged based on its behavior into four fields, i.e. financial, social, technical and environmental criteria. In turn these fields will be analyzed into a lower level of evaluation criteria.

Jan 1, 2006

By Jr. Raleigh

Three run-of-mine bituminous coals, which ranged in rank from low volatile to high volatile A, were floated at nominal -28 mesh (590 µ m), -100 mesh (150 µ m), and -400 mesh (37 µ m) feed particle sizes with selected pyrite depressants and a dispersant. For the coals tested, pyrite and ash-forming minerals were usually rejected best at a -100 mesh feed particle size. Depressant additions tended to improve flotation selectivity between pyrite and coal. When joint dispersant-depressant systems were used at -100 mesh (150 µ m) feed particle sizes, the total sulfur content of the clean coal decreased further. For a comparable coal yield, less fuel oil collector was required for the flotation of -100 mesh coal than was required for the flotation of either -28 or -400 mesh feed.

Jan 1, 1990

By Warren E. Morrison

The expansion of the United States economy in the postwar period has had a tremendous impact on the demand for energy. Not only has total energy consumption increased at an unprecedented rate, but there have been major shifts in the composition or mix of energy resources within the end-use sectors. Because of the numerous interrelationships between substitutable energy resources and their markets, the energy economy can only be analyzed in terms of the trends of its component parts. This problem takes on additional complexity when attempting to chart the nation&apos;s future energy requirements. Total energy consumption can be forecast with reasonable accuracy for periods up to 15 years by relating this to projections of economic indicators. However, forecasting the component parts of the energy economy constitutes a dilemma in that the sum of the projected parts frequently exceeds predictions for total energy. Areas of uncertainty in energy forecasting tend to mount rapidly when proceeding from total energy to the consideration of specific energy resources consumed as fuel, power, or raw materials.

Jan 1, 1965

By Philip A. Bucci

The Florida phosphate industry successfully uses froth flotation to concentrate phosphate in: the particle size range of approximately 28 to 150 mesh. However, as recently as 1965, coarse particles in the range of 14 to 28 mesh generally had not been beneficiated by conventional flotation methods at recoveries high enough to be considered adequate. It has been customary to upgrade this coarse material; by "agglomerate flotation" or "skin flotation" using belts, tables or spirals. While these devices have proved commercially effective, their capacities are much lower than those of froth flotation cells. To determine whether coarse phosphate material could be recovered successfully by froth flotation, Armour Agricultural Chemical Company began a series of pilot and plant tests; in April 1965. Objective of the tests was to compare over-all performance of a froth flotation cell design relatively new to the phosphate industry with results from the belt circuit at the Bartow, Fla., plant.

Jan 1, 1966

By P. Massacci

The modelling of phenomena by nonlinear dynamic Systems Theory representations require the specification and identification of suitable models of the phenomenon and the availability of good optimization algorithms to determine the optimal controls. Stochastic disturbances and difficulties of monitoring the process lead invariably, otherwise, to suboptimal performance. It will be shown that an algorithm can be formulated which will simultaneously identify and optimize such a system. The properties of the algorithm will be derived and its convergence to an optimal control proved. Some results of actual applications will be presented and it will be shown how this approach generalizes easily to optimal control of the actual processing system. These results generalize those of optimal learning and input conditioning.

Jan 1, 1991

By P. Kawahata

Newmont?s Twin Creeks Mine, located in northern Nevada, is producing gold ore from surface mining operations. The ore is currently processed at three different on-site facilities depending on ore type and grade. Processing facilities operate under stringent geochemical blending constraints that must be met from mine ore deliveries and off-site sourced ore. To analyze various strategic options, the technical team utilizes the mathematical optimization approach. However, due to the size and complexity of the operation, there are unique challenges in optimizing life-of-mine production scheduling. This paper describes those challenges and methods developed to take advantage of different scheduling software to effectively compensate each other and result in reasonable guidance. This paper also describes how those scheduling results are reflected in detailed mine plan and cost estimate work.

Jun 1, 2013

By Y. J. Wang

In the mathematical analysis of electrical networks, the electrical devices are often modeled using idealized network elements such as current sources, voltage sources, and resistors. An analogous approach is outlined here for the modeling of mine ventilation networks, which can be considered nonlinear resistive networks. The modeling technique proposed uses five basic (non-reducible) elements: the H element, the Q element, the D element, the R element, and the N element. These elements are characterized by their (a) pressure gain or loss, (b) air quantity, and (c) pressure-versus-quantity relationship, each of which may be known or unknown. In addition to the definition of the basic elements, the necessary conditions for which there exists a unique solution are discussed. This is performed using theoretical developments derived from electrical circuit theory and illustrated in example networks. The proposed procedures are useful in the solution and characterization of mine ventilation networks.

Jan 1, 1996

By d&apos, L. F. G. Assumpcao

Kaolin samples from Rio Capim resources were treated in conventional and superconducting magnetic separators to study the main variables that influence the color removal process. Coating clays and delaminated clay were tested. Retention time (or pulp injection velocity), magnetic field intensity and matrix type were the&apos; variables studied. The feed brightness ranged from 84.7 to 87.6 % ISO for the coating clays and from 80.7 to 85.4 % ISO for the delaminated clay. The results showed unleached brightness values higher than 88 % ISO for coating products and higher than 87 % ISO for the delaminated product, using a conventional magnetic separator with an applied field of 1.5 to 2.0 Tesla. With a maximum field intensity in the superconducting machine of 5.0 Tesla, unleached brightness values higher than 88.5 % ISO for both coating and delaminated clays were attained.

Jan 1, 1995

By Fred C. Bond

Any improvement in the accuracy of commercial comminution calculations under the Third Theory must be accomplished either by increased precision in energy input measurements, or by a better evaluation of the total new crack length produced, as indicated by the feed and product size distributions. Since at the present time feed and product sizes are approximated solely by the microns 80% passes, the most promising opportunity for increased accuracy lies in consideration of their plotted size distribution characteristics. This paper shows how more accuracy can be obtained over an increased range of feed and product sizes from size distribution studies.

Jan 1, 1962

By B. W. Lawrence

Shaft alignment requirements are consistently met using conventional shaft sinking methods. Little attention has been given to achieving similar alignment accuracies using rotary drilled shaft methods. Alignment of these shafts is difficult to control and guarantee. Bare shafts and shafts that use drum hoisting systems can accept some deviation. However, combining drilled shafts with Koepe hoist installations presents new accuracy requirements for drilled shafts. This paper describes the importance of verticality with practical examples, and discusses various methods of measuring verticality and their respective limitations.

Jan 1, 1989

By John Murray, Daniel Ebin, Robert Gould

The Atlanta Plane Train project at Hartsfield-Jackson Atlanta International Airport employed the progressive design-build approach. This provided opportunities for collaboration between the design-builder, design engineer, and owner and the implementation of innovative design and construction approaches. The innovations have reduced risks, allowed for adjustments during design to accommodate new challenges, and provided open-book cost and schedule evaluations. The progressive design-build approach has also allowed for pricing of work to occur in phases—capturing the design/construction challenges as the project evolves and when they are more clearly defined. While this has allowed for pricing to be performed with better project understanding and therefore less contingency, the associated time frame for approvals has required careful consideration to avoid impacts to the schedule. This paper discusses the benefits and challenges of the progressive design-build approach.

Dec 1, 2022

By Felicia F. Peng

The plant data were collected from three streams around a dense medium drum for coarse coal cleaning operated at various volumetric ratio of medium-to-feed. The effect of the volumetric ratio of medium-to-feed (MF) and particle sizes on the performance criteria, g50 and Ep, of the dense medium drum. These measured data were adjusted and calculated for the yields and balanced relative density distributions by mass balanced method based on the statistic principle. These balanced data were then used to formulate the mathematical models of the separation distribution curves for the various feed size intervals. The correlation equations for the g50 and Ep as the function of inverse of the feed size, and MF and total throughput were established. A numerical algorithm utilizing the Secant method, based on the root searching principle, was developed for yield optimization and simulation of dense medium drum separation to improve the separation efficiency and hence the product yield. The relationships between the direct ash content and relative density of the particles in feed and the products were established and incorporated into the numerical algorithm for predicting the product quality.

Jan 1, 1996

By D. K. Dysinger

The U.S. Bureau of Mines investigated leaching of chalcopyrite with sulfuric acid-oxygen under conditions anticipated during in situ leaching. A central composite experimental design was chosen to study oxygen pressures of 150, 300, and 450 psi, leach temperatures of 35?, 65°, and 95° C, oxygen-to-chalcopyrite mass ratios of 0.5, 1.0, and 1.5, leach times of 8, 16, and 24 hours, initial acid strengths of 0.6, 1.2, and 1.8 g H2SO4/g chalcopyrite and pyrite to chalcopyrite mass ratios of 0, 1, and 2. The leaching kinetics were consistent with the shrinking core model. A quadratic response surface model was used to determine linear and interaction effects of the design factors on rate constants from Arrhenius correlations.

Jan 1, 1993

By James Douglas

For the past several years, inflation has placed increasing pressure on our economic system. The total effect of inflation is complex when combined with other factors which affect the economics of equipment. A mathematical model is described herein which can be programmed on a computer to determine the effect of inflation on economic life and profits after taxes. The computer output results in graphic plots which clearly show the relation of various percentages of inflation to life and profits. Inflation has become a common topic of conversation in the recent past. What is it and how can it be measured? What effect does increased inflation have on equipment policy? Research now in progress at the Construction Institute at Stanford University is beginning to unravel some of the mystery of inflation. As a start, let us answer the first question by defining the word inflation. The dictionary says that inflation is "an increase in the volume of money and credit relative to available goods resulting in a substantial and continuing rise in the general price level. It appears, in fact, that we are in an inflationary spiral which is "a continuous rise in prices that is sustained by the tendency of wage increases and cost increases to act on each other." 3 Inflation behaves just like compound interest. It takes more dollars of future years to buy an equal amount of a given commodity, be it a material or a service. Let us assume an annual inflation rate of 5 percent. Assume that 1Associate Professor of Civil Engineering, Stanford University, Stanford, California. 2Webster&apos;s Seventh New Collegiate Dictionary, Springfield, Mass., G. and C. Merriam Co., 1969. 3Ibid.

Jan 1, 1972

By Daniel R. Stewart

The function of the geological engineer is to assist in mine planning and operations by collecting, interpreting, and applying geologic data to the solution of engineering problems. The geologist supports this effort by collecting additional geologic information specifically useful to the engineer. This use of geologic information reinforces the value of mine geology to the mining process beyond the traditional role of orebody definition. Work discussed includes: evaluation of caving strategies at the Climax and Henderson mines; support definition and slope stability at the Climax mine; and some uses of geology in cavability estimation for the Mount Emmons project.

Jan 1, 1983

By F. Calizaya, M. G. Nelson

This paper presents a summary of basic requirements for the design, installation and operation of booster fans in coal mines, especially in deep and/or extensive mines. It includes a brief description of the major steps that should be followed to ensure that these units are used in coal mines safely and efficiently. The guidelines were prepared based on the standards and regulations adopted by two prominent coal mining countries, the best practices developed by the mining industry, and the applicable standards used in the United States for the fail-safe operation of main fans.

Jan 1, 2015

By D. Bristow, D. Baker, K. Awuah-Offei, A. ur Rehman

While a body of work exists on intelligent systems for guiding occupants out of buildings during an emergency, the problem of guiding miners out of a mine during an underground emergency has not been explored. Underground evacuation fundamentally differs from building evacuation because of differences in the regulatory regime and uncertainty regarding the number of occupants. The potential for implementing an intelligent miner guidance system is buttressed by the fact that miner tracking systems, along with communication and sensor networks, already exist in underground mines. This work presents a method based on a local positioning system, in the form of a network of “nodes” at major “intersections,” which can then be used to guide miners to safety. We have developed a path-planning algorithm, based on Dijkstra’s algorithm and the local positioning system that can provide miners with the optimal escape path in an emergency. The algorithm is validated with scenarios at the Missouri University of Science & Technology Experimental Mine demonstrating the potential to include smart technology in mine emergency management and response planning. INTRODUCTION Underground mines are hazardous environments with a higher than usual risk of safety emergencies where miners have to evacuate the mine to save their lives. Mines have always trained miners to evacuate or shelter-in-place in minimum time. Jalali and Norrozi (2009) opined that the three major components that help miners in case of emergency are pre-planned optimal escape routes, decreasing delays, and improving the education of miners. In fact, Goodman and Kissel (1990) suggested that fatalities arising from mine accidents could be reduced by 50% just by decreasing delays in finding the pathways in case of emergency. The proposed work can assist miners in finding escapeways quickly in case of emergency. It is very important to have a pre-planned evacuation strategy that is clearly communicated to miners to ensure the safety of all (Conti, Chasko & Wiehagen, 2005).

Jan 1, 2019