Search Documents

By S. K. Singh, J. Shepherd

Feather-edging, a major source of injury and fatal accidents in Australia, South Africa and the United States, refers to a phenomenon in which the roof at the goaf edge falls, often suddenly, as a thin wafer of rock that overrides conventional timber breaker lines. The fall may adversely affect a working bord at a distance of 15 m (50ft) or more from the goaf edge. Feather-edging typically occurs in relatively massive, strong roof strata such as sandstone or conglomerate. This paper presents the results of a test in which a concentrated row of fully grouted bolts were used to prevent feather-edging in an Australian pillar- ("total-") extraction coal mine. The test demonstrated that the bolts could resist feather-edging.

Jan 1, 2000

By L. S. Jen

The seven most important base and precious metals produced in Canada are copper, nickel, lead, zinc, molybdenum, gold and silver. Because much of Canada's mineral production is exported in the form of concentrates, it is of special interest to keep track of the production of these various concentrates and the capacity utilization of the concentrators producing them. Annual data surveys on individual concentrators, coupled with the interactive capabilities of the computerized mineral product ion system through a custom-tailored, fairly low-cost computer system configuration are used for ongoing monitoring. Rapid analysis of concentrator production can be carried out on a disaggregated basis that allows policymakers to see specific reasons for significant changes over the years.

Jan 1, 1986

By W. A. Niepelt, F. A. Locher

Flow in steep cascades may lead to the occurrence of a nearly periodic train of waves known as slug flow. This, in turn, may result in overtopping of the channel walls and problems with energy dissipation in receiving sumps. Experimental data from an operating facility was used to extend clear water technology for predicting the occurrence of slug flow to conditions with slurry flows. A design methodology and a design chart to determine the region of steady flows is presented that will permit the design engineer to avoid slug flow in cascade systems for conveyance of slurries.

Jan 1, 1990

By John D. Nelson, Clint L. Strachan

Drainage of tailings impoundments is a key issue for impoundment stability, water control, seepage control, and reclamation. Drainage control is an established operating practice where climate and site conditions permit, such as in South Africa and various mines in North America. In these areas, drainage control is primarily used to maximize tailings densities and to provide adequate impoundment stability. Drainage practices during operation also become an important issue when tailings impoundments are reclaimed. Time required for cover placement and post- reclamation seepage control depends greatly on the ability for tailings to drain and consolidate. This paper discusses drainage issues associated with gold tailings impoundments in terms of mechanics of saturated and unsaturated flow and experience with design and reclamation of tailings impoundments.

Jan 1, 1988

By N. L. Weiss

General The crushing of run-of-mine hard rock ores is the province of jaws and gyratory primary crushers described in the two preceding chapters of this section. While it is now seldom difficult to make a choice between the two to suit a specific set of circumstances, the governing factors merit a review, and that is the purpose of this chapter. For every size of feed there is a crusher of either type that can handle it, and it is only when the desired crushing rate in toss per hour is considered together with the rock size that the preference for one type over the other is truly significant. When Taggart completed his Handbook of Mineral Dressing there were already in opera-

Jan 1, 1985

By Thomas W. Camm

A WINDOWS-based object-oriented expert system for prefeasibility evaluation of hard rock mines is being developed at the Western Field Operations Center (WFOC) of the Bureau of Mines. Designed for use with the Bureau's Cost Estimating System (CES), this expert system assists an evaluator in choosing an underground mining method, and the related design parameters. The system provides the engineering and design guidelines necessary for an evaluator to perform a prefeasibility type cost estimate.

Jan 1, 1992

By Ahmed M. Nofal

This article reviews some important characteristics of the known Egyptian phosphate deposits, such as mining conditions, transport criteria, quality of products affecting their export markets and utilisation in fertilizers industry. Special attention will be given to the newly discovered large deposit of Abu-Tartur with some billion tons of ore reserves. A big project is now under implementation on Abu-Tartur deposit where the long-wall method of underground mining will be applied and a flow sheet of beneficiation will be in operation including a particular feature nontraditional in phosphate processing: high-intensity magnetic separation to eliminate dolomite impurities. Comparison with some international phosphates will be tried in order to trace the situation of Egyptian phosphates in the world market.

Jan 1, 1993

By L. A. Panek

A new pillar strength formula is presented. It incorporates a function [IF] of size and shape that takes into account the size-shape interaction effect as well as the enhanced strength exhibited by wide pillars. Existing pillar formulas, lacking these capabilities, are not suitable for extrapolating small-specimen test results to mine-pillar sizes and shapes. Interpreting compressive strength test results as function of [Y] reveals wide-pillar behavior in much old test data. Model relationships are discussed, along with their scaling implications.

Jan 1, 1995

By Russell Dittrich

The Kinross DeLamar Mine has been operated for more than 17 years producing precious metals doré from ores, principally silver bearing with associated gold coproducts. In late 1995, the Stone Cabin ore body was commissioned and the site began a phased shift from silver dominance to gold dominance. The Knelson concentrator was selected to remove gold from a portion of the cyclone under- flow stream in the grinding circuit.

Jan 1, 1998

By Ernest K. Yanful, Paul H. Simms

The lysimeter is a useful tool for evaluating the performance of mine waste covers or liners. A major problem with its application is the possibility for preferential flow into or away from the lysimeter, if the lysimeter soil is finer or coarser than the barrier soil or sub-base soil. Analysis of a field lysimeter using a two-dimensional unsaturated-saturated liquid flow model suggested that preferential flow would occur and little or no water would be collected; however, in the field, the lysimeters collected significant amounts of water. A similar discrepancy was found between the observed and predicted water balance of a simple laboratory test simulating the lysimeter design. Vapour flow and partial flow, two phenomena not generally simulated in conventional flow models, are possible explanations for the difference between field and laboratory observations.

Jan 1, 2000

By Bart Lorang

Mining and mineral processing companies have historically leveraged technology and science to the fullest to reduce costs and improve product. Information technology is arguably one of the fastest moving technologies used by the mining industry. However, the business model for managing that technology and IT professionals often is fundamentally the same model that evolved from 1960's mainframe era. This paper will present a perspective of today's technology; review emergent computing technologies and attempt to id- advancements in computing anticipated in this decade. It will then discuss how the traditional IT model fits the technologies of today and the next decade. It will suggest roles IT professionals may play in the future to best leverage these technologies.

Jan 1, 2002

By T. F. Torries

Market data commonly perceived as being useful to industry for decision making include prices, production and trade quantities, production and transportation costs, stocks, customer's needs, and competitor's qualifications. Costs and factors affecting costs are particularly important in determining competitive positions and possible future prices. These costs include relative cost of production as well as cost experienced by the buyer in making the final product. Care must be taken to calculate costs in a consistent manner to achieve meaningful analyses.

Jan 1, 1987

By A. S. Polubinsky, V. P. Chernyak

A further development of the theory of heat- and mass transfer in the system “strata - mine opening" is necessary for an improvement of the existing technique of heat calculation of mines and other underground constructions. A generalized boundary problem of heat- and mass conduction in strata around an opening as a theoretical ground for that purpose and several particular situations, important from the point of view of an opening and surrounding strata heat state analysis, as well as results of numerical experiments executed for such analysis are presented.

Jan 1, 1997

By L. Wade, D. R. Pearce

A detailed account is given of the spectral ratio laboratory method for the determination of seismic velocity and attenuation through rock cores under simulated in-situ stress conditions. An account of a computer program called AUTOQ is described for automatic processing of a complete set of laboratory results. Some of these results are shown and discussion is directed to- wards the suitability of in-situ velocity or attenuation measurements in determining rockmass condition or stress regime.

Jan 1, 1996

By Joachim H. Schubert, David G. Hulbert, Ian K. Craig, Roger G. D. Henning

This paper presents a stabilizing controller for flotation plants which uses a quasi-multivariable technique. The controller monitors all the levels in the plant, and by anticipating interactions between various parts of the plant, is able to stabilize the plant far more successfully than the normal plant control. Once stabilizing control has been achieved, optimization of the process becomes easier and more sustainable. An estimate of the improvement in metallurgical performance is made and a singular value analysis was conducted to verify that the multivariable algorithm will theoretically control better than a collection of individual PID loops. Metallurgical results are presented to show that the improvements are attainable in practice. Control by the Mintek algorithm was alternated with normal plant control, to show that the improvements are statistically significant.

Jan 1, 1995

By Guoming Liu, Weibai Hu

The designing aspects of column profile, cross-section and height, types of aerator or air sparger, and feeding and discharging devices have been designed and tested. In operating aspects, the flotation column: has beer, compared with the conventional mechanical flotation machine in large- scale plant practice. It has been found that the reagent conditioning time and the slurry residence time required in the column are longer than those in the mechanical flotation machine. The general opinion is that the flotation column can show some effectiveness in specific cases as long as it is properly designed and carefully controlled.

Jan 1, 1988

By P. J. Kientzler, Y. C. Lo

The current study is concerned with the analysis and attempt at simulating the product size distributions obtained from a vibrating ultrasonic device. Systematic experiments of comminution were performed with natural sizes as well as monosizes in order to understand the breakage behavior of the device. A precise analysis of the device's breakage performance in the case of fine grinding of alumina samples will be presented. Initial steps to model the breakage events using a detailed mathematical algorithm will be discussed.

Jan 1, 1992

By R. J. Wesely, A. D. Zunkel, Tracy B. Braun, Philip L. LeHoux

An overview of gold processing operations at Barneys Canyon Mine is presented with particular emphasis on ore agglomerating experience, leaching and metallurgical accounting practices, and carbon column plant operating approach. The mine, located thirty kilometers from downtown Salt Lake City, is just eight kilometers north of the Bingham Canyon copper mine. Mining was initiated in February 1989 and the first gold was poured in September 1989. Through year-end 1992, approximately 7 million tonnes of ore have been processed and 12,000 kg of gold have been produced. Gold recovery is in excess of 85 percent.

Jan 1, 1993

By S. S. Nadgauda, A. J. Hathaway

Typically, as long as the coal quality is within the specified range, electric utilities have used delivered cost of fuel per million Btu as the primary criteria for qualified coals when making coal-procurement decisions. Such an approach may not fully address the total cost of using different quality coals at a given plant. A practical and easy-to-build model is described for estimating plant-specific utilization costs for coals of different qualities. Examples are included to illustrate the modeling results for plants operated by two utilities. While the model has certain limitations, it does represent an improved method for evaluating coal bids, and, consequently, reducing generation costs.

Jan 1, 1990

By M. J. Klishis

This paper presents the findings of a study on roof bolter's hazard exposure. A "microanalysis" of accident data was combined with ergonomic observations of roof bolter operators to categorize bolting-related injuries, and, from this, a checklist was constructed. Bolting-related problems were identified as situations that could expose bolter operators to hazards. Approaches to avoid these situations were applied at six mining operations to evaluate specific problems in root bolting operations. The research emphasized the importance of analyzing worker behaviors in the context of mining situations and equipment-design problems that lead to human-error accidents.

Jan 1, 1996