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By James P. Rider, Robert P. Vinson, Fred N. Kissell, Jon C. Volkwein, Gregory J. Chekan, Jay F. Colinet

The Thermo-MIE personal DataRAM dust monitor (pDR) is a light-scattering instrument approved for use in gassy underground mines by the U.S. Mine Safety and Health Administration (MSHA). However, the use of lightscattering monitors has been inhibited by concerns about inaccurate readings resulting from changes in dust size distribution and composition, as well as concerns about the impact of moisture in the mine air. Because of this concern, the National Institute for Occupational Safety and Health (NIOSH) has evaluated the pDR using available data from laboratory tests and mine surveys. The data show that accuracy can vary widely from test to test and mine to mine. In most cases, the results can be improved by using a companion gravimetric measurement to adjust the pDR data.

Jan 1, 2005

By G. T. Lineberry, R. Q. Honaker

Coal extraction typically results in the recovery of pure rock that ranges from small to very large quantities depending on seam thickness and other characteristics. The removal of pure rock may allow the recovery of three times the amount in middling coal particles, which has significant economical benefits. In an industrial example, a 150% increase in revenue was realized from deshaling a low-ash, run-of-mine coal and blending with a processed clean coal product. Deshaling is the process of removing pure rock from coal, which normally involves a high-density separation in a gravity-based process. The removal of the relatively pure rock near the point of extraction has the potential to further enhance the economics of an operation due to reduced materials handling and refuse storage costs.

Jan 1, 2004

By M. Niinae, Y. Nakahiro, K. Yamaguchi, T. Wakamatsu

The rare earth magnet has a good performance and the production is increasing year by year. Two types of rare earth magnets are presently made as industrial products. One is a Nd-Fe-B intermetallic compound magnet and the other is a Sm-Co alloy magnet. The mixed scraps of Nd-Fe-B intermetallic compound and Sm-Co alloy are sometimes produced in the step of production. Therefore it is desired that a recycling system of mixed rare earth magnet scraps should be established. In the present study, hydrochloric acid leaching of the oxidizing roasted products of Nd-Fe-B intermetallic compound and Sm-Co alloy and solvent extraction of metals such as Nd, Sm, etc. are tested to obtain the fundamental data for the hydrometallurgical treatment of the mixed rare earth magnet scraps.

Jan 1, 1995

By Deepak Gupta, Brij M. Moudgil

Attempts were made to improve the recovery of coarse phosphate particles by adding selected frothers or precoated fine particles. A number of frothers for floating, specifically coarse coal and metallic minerals, were examined. Two of the frothers increased the flotation recovery of coarse phosphate by 3% on bench scale. Plant evaluation yielded improvements in overall phosphate recovery in the presence of these frothers. Addition of fine particles was also found to enhance coarse flotation under given conditions. Size, amount, and hydrophobicity of the fines added was determined to have a major influence on the coarse flotation efficiency. The grade of the product with and without frothers and particulate additives remained the same. Change in froth stability and viscosity are believed to be the primary reasons for enhanced recovery of coarse phosphate particles.

Jan 1, 1989

By Leo Langland

One of the primary functions of the Geotechnical Services-Materials section of the Arizona Department of Transportation (ADOT) is locating, sampling, and evaluating potential aggregate deposits throughout the State. This information is essential in designing, estimating, and bidding highway construction projects. The nature of materials used for aggregate varies greatly within Arizona. The northeastern or plateau section is famous for its scenic sedimentary formations that are, how- ever, too soft to make suitable aggregate. Volcanic materials are widely used in place of more conventional geologic units. In contrast, the southwestern, or Basin-and-Range section, contains a relative abundance of good aggregate, especially a diversity of gravels. The paper will review the off ice, field, and laboratory methods used by the ADOT Materials Section in satisfying its needs for aggregate information in Arizona.

Jan 1, 1987

By P. Somasundaran, Brij M. Moudgil

All the major interfacial technologies encountered in mineral processing involve adsorption of surfactants and/or polymers. With the need for processing low grade complex ores it is imperative that conventional techniques such as flotation and flocculation be extended to meet the challenge of treatment of fines. Addition of surfactants or polymers is indeed not limited to the solid-solid separations but extends to particle size reduction in the form of grinding aids and dewatering operations as well. Although progress has been made in recent years to understand the science involved in various interfacial processes, more challenges and opportunities exist today than ever before in processing of the low grade finely disseminated ores. A brief review of the recent advances and the challenges in mineral processing, especially, those related to the interfacial technologies is presented.

Jan 1, 1989

By R. J. Sweigard

Many states are considering the need to establish or modify policy relating to the disposal of coal ash. One of the primary concerns is the impact of leachate from the ash disposal sites upon groundwater and nearby bodies of surface water. A detailed site investigation was conducted at a coal ash disposal facility associated with a power generation station. The disposal site is situated alongside a major river. Monitoring wells were installed and soil samples were taken for characterization. Groundwater models were used to simulate migration of leachate from the disposal site toward the river. Such models have the potential to be used to verify regulatory compliance. This paper addresses the validation and adaptability of these models to this case and their usefulness as possible tools to be used in future environmental audits.

Jan 1, 1993

By M. Jaramillo

The expanded west pit of the 15 Mta (13.6 stpy) El Cerrejon mine will eventually reach a maximum depth of 270 m (890 ft). Slope-stability evaluations indicated that this depth, combined with structural complexities, would create a serious risk of footwall instability. Stabilization calls for anchoring the footwall by the installation of 9- to 33-m- (30- to 108 ft-) long multistrand steel cable bolts. For each of the 15-m- (50-ft-) high mining benches, a row of bolts is installed with variable horizontal spacing, depending on the dip magnitude. Cable bolting is now standard operating practice, and an estimated 11,800 bolts will be installed during the life of the mine. Results to date have been satisfactory in terms of the stability condition of the bolted slopes.

Jan 1, 1997

By K. Verghese, H. M. Lee, R. P. Gardner, K. Boateng

Results of work on the development of a phenomenological model for the continuous flotation process wing short-lived radioactive tracer techniques for determining model parameters is reported. A model that incorporates a flotation first-order rate constant and a residence time distribution based on the cross-flow finite-stage (CFFS) model has been derived and investigated. The short-lived radioactive tracer techniques and the nonlinear search methods necessary to extract the model parameters have been developed. The conditions under which all the model parameters can be extracted from a single radiotracer experiment are detailed and illustrated. A micro- computer-based unique data logging system has been designed, assembled, and implemented for collecting the necessary transient radiotracer data. Results are reported for a continuous laboratory flotation process for the two systems, mica ore and coal.

Jan 1, 1987

By Patrick Linzer

The majority of existing models describing (methane) gas transport within, and liberation from, coal structures treat these as continua wherein two main gas flow modes (diffusive and Darcy permeable) prevail, and use finite difference techniques to generate solutions to the resulting multivariate parabolic partial differential equation(s). Isotropy and homogeneity in the physical and geometric coal structure properties are often assumed, and the existence of fundamental random fluctuations in these proper- ties is not catered for. The model proposed herein does not suffer these inadequacies, and its efficiency is enhanced by the replacement of the diffusion equation by an accurate approximation. Dynamic mining activity, gas contributions made by the geology surrounding the mining seam, goafing of overlying strata and the effects of induced strain are all taken into account.

Jan 1, 1995

By A. R. Zambrano

Equations for power draft, capacity and work input for predicting the performance of industrial grinding mills are derived based on torque measurements using a laboratory instrumented mill. These derivations are based on mechanical principles and on the first-order kinetics of the grinding process. Rittinger's, Kick's and Bond's laws express work input as work index (Wi) times a particle size function. It is proposed that these laws are only particular cases of more general expressions having the particle size function raised to an exponent, i.e., the work exponent (We). Case studies illustrate the excellent prediction of the Wi - We models compared to the three mentioned laws, and, from the data, the corresponding general mill-sizing equation is derived. Key words: Grinding mills, Comminution, Work index, Mill sizing

Jan 1, 2003

By S. Subbarayan, S. Chander, M. S. Klima

A laboratory study was conducted to investigate the potential for recovering anthracite from coal preparation-plant tailings. The study included washability analyses, cyclone simulations and froth flotation testing Samples were collected from either the tailings streams or the slurry ponds of five anthracite-cleaning plants. From each sample, a washability analysis was conducted on the 28x100 and 100x200-mesh fractions. Using the above data, along with published partition data, simulations were performed with various cyclone-staging arrangements for both water-only and dense-medium cyclones treating the 28x200-mesh fractions. Separate froth -flotation tests were conducted on the 28x100- and 100x200-mesh fractions from three of the plant samples. The washability, simulation and flotation results are presented as grade-yield curves.

Jan 1, 1996

By B. Ainsworth

The 1972 discovery of the Howards Pass lead-zinc deposit was the product of systematic regional geochemical surveys used to evaluate conceptual geological models for the metal-rich black shales of the Selwyn Basin. Motivation of personnel involved in all aspects of work was as critical a factor to the success as the existing corporate attitudes and infrastructure. Exploration programs were flexible but maintained a focus only on targets of sufficient economic potential to support operations in remote locations. Direct costs for the programs that lead to the discovery were in the order of $500,000 (Canadian 1972). Geological reserves today stand at over 500 Mt (511 million st) of 7% combined lead-zinc, containing a higher grade zone of nearly 10 Mt (11 million st) of 16% combined lead-zinc.

Jan 1, 1991

By Erie F. Wolstenholme

The purpose of this paper is to describe work undertaken, within the System Dynamics Research Group at Bradford Management Centre, into the development and application of a System Dynamics model of an international mineral industry; aimed at providing a basis for analysis of the interrelationship of supply, consumption and price over time, under different production and stocking policies. A review is presented of some of the major characteristics and problems associated with such industries. This is followed by an outline description of the model and the way it has been applied to examine various supply responses, in the light of changing consumption patterns. Demonstration results deal with model validation and with analysis of international buffer stocks and conflicting supply policies on the historic situation in the copper industry.

Jan 1, 1979

By Graeme Lyall, Oy Leuangthong, Clayton V. Deutsch

There are many variables to consider in the evaluation of nickel laterite deposits including the concentrations of nickel, iron, silica, and magnesia. These variables show complex relationships with each other such as mineralogical constraints, non-linear correlation, and heteroscedasticity. The complex multivariate relationship between the variables cannot be reproduced by conventional Gaussian or indicator geostatistical techniques. We introduce the stepwise conditional transformation method as a pre- and post-processing multivariate transform for the stochastic simulation of a nickel laterite deposit. Transformed data are multiGaussian and independent at h = 0; thus, cosimulation can be avoided after verification that variables are independent at all lag distances. Back transformation restores the features of the input multivariate distribution to the simulated realizations. The complex multivariate correlations are reproduced and sensitivity issues are addressed.

Jan 1, 2002

By F. F. Peng, Y. Xia

In modeling of hindered-settling bed separators, the published separation mechanisms are based on differences of particle density and size distributions, without the details of complexity of particles-liquid interactions. A fluid dynamic model for the separator is developed using Euler-Lagrange approach of Computational Fluid Dynamics (CFD). Fluid motion is obtained from solving the movement of liquid governing equations. The damping effect on flow pat-terns caused by the movement of particles resulted in liquid-particle coupling is included in the model. Effects of particle size, and particle density compositions, feed rate, feed water flow rate, upward fluidizing water flow rate, etc., are simulated in the 2-D separation model. Flow pattern effects on the separation of fine particles in the separators with center downward-flow and side cross-flow feed systems are investigated.

Jan 1, 2004

By G. E. Jones, G. K. Hoffman

Two Sun Juan Basin studies were completed through the USGS National Coal Availability program. The study areas are in the northwest Bisti field (Fruitland Formation) and in the eastern Standing Rock field (Menefee Formation). In the Bisti and Standing Rock areas, the original coal resource5 are estimated at 4.66 and 3.1 7 Gt (5.14 and 3.49 billion st), respectively. The Bisti coal resources are greatly reduced by the Bisti-De-Nu- Zin wilderness area, which contains an estimated 1.13 Gt (1.25 billion st) of coal. Technological restrictions remove 32.5% from Standing Rock's original resource. Available resources are 60%. 2.79 Gt (3.07 billion st), of the Bisti original resource and 65%, 2.07 Gt (2.28 billion st), of the original Standing Rock resource.

Jan 1, 2002

By E. F. ‘Pat’ Nelson, Richard Broom

Our portion of this afternoon’s session is dedicated to the operation of automatic process control associated with small to medium size primary or SAG milling circuits. In recognition of the subject matter of this symposium, specifically precious metals, our historical reference is Rosario Dominicanna in the Dominican Republic, one of the largest gold producers in the Western Hemisphere. Plus a backward glance to review very briefly the initial performance of the big primary mills at Island Copper in British Columbia and Pima IV in Arizona. We will then get to the subject at hand with a discussion of a retrofit control logic recently installed on a 5000 hp primary mill. The focus of this review is the simple, inexpensive, and cost effective character of this retrofit installation.

Jan 1, 1984

By Nicola Della Valle

The Singapore Land Transport Authority (LTA) is currently expanding capacity by extending their Metro system from South of the city to the North East end of the island. The scope of Contract 704 involved excavating a long reach of tunnel which had a complex rock/soil interface comprised of fresh granite overlaid by clayey sand. Two 6.5 m diameter Earth Pressure Balance (EPB) TBM’s were used to bore the tunnels. These machines were designed so that both hard and soft rock could be excavated. The cutter head was equipped with a combination of both rippers and disk cutters. Soil conditioning was achieved by delivering foam through a multiple port injection system. This very irregular profile of the interfaces posed many challenges to the equipment and the people.

Jan 1, 2001

By Tim Neil, O&apos

Acid rain legislation, the new tax package, excess coal capacity, the effects of low oil prices, how to increase coal exports: These were among the items discussed at the May 4-7, American Mining Congress coal convention in Pittsburgh. Some 2000 people attended the convention, which also offered 15 technical sessions. As always, the state of the domestic coal industry might be characterized as "long-term promise, short-term problems." And one of these problems is acid rain. Acid rain The proposed acid rain legislation in Congress could be the most costly piece of environmental legislation ever written. In its present form, the measure could cost the nation up to $110 billion over the next 15 years. Rep. Henry Waxman's (D-CA) bill, HR 4567, would mandate large reductions in sulfur dioxide emissions from coal-fired power plants. The bill has more than 150 Republican and Democratic cosponsors. Ed Addison is president of the Southern Co., one of the nation's largest utilities and users of domestic coal. Addison noted that America's electric utility industry buys and uses nearly 85% of the coal consumed in this country. He said Waxman's bill would drive up prices of low-sulfur coal, raise electric rates, and force miners out of work in high-sulfur coal regions. In repeating a standard coal industry response, Addison said the Clean Air Act is doing the job. In recent years, while coal use has gone up, S02 emissions have gone down. Current air pollution standards are producing cleaner air, he said. Despite concern over HR 4567, the bill's future is uncertain. Several coal industry executives and analysts predict the bill will die under weight of opposition from coal, utility, and steel interests. But the acid rain issue is gaining momentum. Future legislation of some kind is likely. Meanwhile, research continues to develop clean coal technology to deal with the S02 problem. Commercialization of these front-end technologies currently lags public sentiment for acid rain legislation. Ground water runoff and contamination is another area where future legislation would seem likely. Already, one bill has been introduced in Congress. A second is being drafted. The impact of such legislation may be significant according to Bruce Leavitt, a hydrogeologist with Consolidation Coal Co. He said if current proposals are adopted, there will be more federal, state, and local government involvement in ground water regulation. In any event, the coal industry can expect to see more emphasis on preventing acid mine drainage and on water replacement, according to Leavitt. He urged those in the coal industry to present information about mining and ground water. That is needed to prevent misdirected state and federal programs, he said. Another coal industry concern is excess capacity. The industry has the mines, equipment, and employees to produce 15% more coal than at present. Problem is, the markets are not there. Slower-than-predicted growth in electric utility coal use has kept sales sluggish. There are also tax uncertainties. Congress is considering repeal of the investment tax credit and elimination of black lung payments and excise taxes as deductible expenses. One analyst estimates the coal industry would lose $1.1 billion in five years, if the changes are approved. In addition, there are the usual concerns about excessive governmental regulations involving safety and environmental matters. Bill Kegel, for example, said these regulations mean extra costs and delays in developing mines. Kegel is president and chief executive officer of the Rochester & Pittsburgh Coal Co. More than half the electrical power in the US is generated by coal-fired plants. That percentage could slip by a couple of points as nuclear generators come on-line the next few years. About 1990, though, we will see the end of US nuclear plant construction. No new nuclear plants have been scheduled since 1978. So any growth in electric power use should benefit the coal industry. BethEnergy - High Power Mountain During 1985, BethEnergy - a Bethlehem Steel Corp. - subsidiary developed High Power Mountain, a 1.8-Mt/a (2-million-stpy) surface mine in West Virginia. Construction saw movement of more than 3 hm3 (4 million cu yds) of earth. A computerized 544 t/h (600 stph) heavy media cyclone prep plant and a 3.6-kt/h (4000-stph) railroad loadout facility were built in six months. And a 5.6-km (3.5-mile) railroad spur and loop bridging a major highway were constructed. Larry Willison of BethEnergy noted the project's ambitious construction schedule. It was forced by the need for the project to be market driven and - lacking available capital - externally financed. BethEnergy did several things before obtaining with Detroit Edison a market for 0.9 Mt/a (1 million stpy) of coal. Willison said his company prospected and proved the eastern half of its 8-km2

Jan 7, 1986