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By Ralph P. Hackl

The Congress gold property, located near Goldbridge, B.C., is extremely refractory with most of the gold disseminated in fine- grained arsenopyrite. Metallurgical testwork conducted by Giant Bay Biotech Inc. indicated that biooxidation pretreatment was capable of increasing cyanide gold recovery from the ore to greater than 90%. To determine if the bioleach process could be successfully scaled up, a 225 cubic meter commercial size bioleach reactor was built and tested at the mine site in 1989. At that time the tank was the largest bioleach reactor ever operated. This paper discusses our experiences in operating the tank, summarizes some of the data obtained and describes the problems encountered.

Jan 1, 1990

By F. Mensah-Dwumah, W. H. Baker, G. W. Clough

INTRODUCTION The practice of injecting chemical grouts into permeable soils in order to stabilize them for tunnel construction is a common procedure in Great Britain, Europe and Japan. In this technique, the grout penetrates the soil in a fluid condition, but hardens or "sets-up" in about one hour due to a chemical reaction. As a result, the soil, is strengthened and made less pervious, and this, in turn, reduces ground surface movements, limits ground water flow, and controls movements of the heading during tunnel construction. It is only within the last five years or so that this technology has been used in the United States. Most of the applications have been involved in the work for the Washington Metropolitan Area Transit Authority (WMATA) subway construction. The experience gained from this work is, in many instances, unique and should serve to guide use of the grouting technology in future projects. This paper documents five WMATA case histories; information is provided as to the soil conditions, method of treatment, reason for treatment, and tunnel performance. Locations of the five projects covered by this study are indicated in Figure 1. All are within the boundaries of the District of Columbia and involve soft ground tunnel construction. Basic information for the case histories is given in Table 1. Tunnel sizes and depths below the ground surface as well as general soil conditions are similar in all instances. The tunnels are about six meters in diameter and are located so that the crown is five to ten m below the ground surface. The soils typically consist of alternating sand, clay and silty sand strata. However, soil stratification details are

Jan 1, 1979

By D. A. Norrgran

The process of magnetic separation is based on the differences among magnetic susceptibilities of various mineral species. Performed either wet or dry, the separation has application in both the recovery and concentration of value minerals and in removing deleterious mineral constituents from a product stream. There are two major catagories to be considered when addressing magnetic separation of minerals. The first catagory refers to particle characterization and relative differences in magnetic susceptibility. The second catagory refers to design parameters and the magnetic field generated by the separator.

Jan 1, 1987

By John N. Murphy, Edward F. Fries

The availability of fast, low-cost computer hardware and advanced software is opening new opportunities for minerals extraction and processing. Programmable Logic Controllers (PLC's) are currently used extensively in the minerals industries; this paper looks beyond PLC's and that vintage of “computer control”--it looks toward what the authors see as new in the next five years. Topics covered include expert systems, neural networks, intelligent signal processing, and hierarchical controllers as applied to mining and mineral processing operations.

Jan 1, 1993

By Robert W. Greene

Next month, American Commercial Barge Line Company will begin moving coal from mines on the old Camp Breckinridge property in Western Kentucky to TVA's new 2600 MW steam plant at Cumberland City, Tennessee. By April of 1973, this movement will reach a level of 7,000,000 tons per year. TVA bought the coal rights to this property from the General Services Administration in 1965 for approximately $7 million. The reserve contains about 120 million tons of recoverable No.9 coal, and about the same recover-able amount of No. 11 coal. TVA then contracted through competitive bidding with Peabody Coal Company to mine the No.9 seam through two slope shafts. The mines are about 300 feet deep and are separated by the one major fault on this property. The mine portals are approximately 3-1/2 miles apart, with the northern portal being over nine miles distant from the Ohio River (see Figure No.1). In 1969 TV A took bids on alternate methods for transporting 120 million tons of coal to Cumberland City at seven million tons per year. These alter-natives included overland transportation to the Ohio River by rail or conveyor, water transportation from Union County, Kentucky to Cumberland City, and total transportation packages from Camp Breckinridge to Cumberland City. The latter could be a joint land/water package, or all land (rail). Ultimately American Commercial Barge Line was awarded an $88 million package transportation contract to convey the coal from Camp Breckinridge to Uniontown, Kentucky; to store it at Uniontown in a quantity sufficient to allow ratable delivery to the steam plant; and to barge from Uniontown to Cumberland City via the Ohio and Cumberland Rivers.

Jan 1, 1971

By Jiro Yamatomi, Susumu Takemura, Osam Sakai, Hiroshi Shimotori, Yoshio Otsuka

The Toyoha Mine is operated under extremely high rock temperature. The geothermal heat is 10 to 20 times more active than the average of the Japanese Islands. The highest temperature ever observed in exploration drill holes is 242°C that must be equivalent to those of the geothermal fluids utilized for power generation in Japan. In order to improve the underground climate, the mine has a plan to introduce paste backfilling and to effectively reduce the heat flows from the mined out stopes. The surface flow test was carried and the second test is being arranged in underground.

Jan 1, 2001

By B. Rao Pothini, Julio H. Thaler, W. L. Finlay

The White Pine room-and-pillar mine started in 1955 from a suboutcrop, down gentle dips, and with a competent sandstone roof. As mining depths increased, extraction decreased 1% every 35 feet. Moreover, roofs became shaly and less competent, and regions of high fault and joint densities, sometimes with and some- times without high lateral stresses, increased the tendencies towards roof falls. Instinctive reactions towards narrower openings did not alleviate the problem. Careful consideration of rock mechanics principles culminated in the development of two variants to the conventional room-and-pillar mining system based on the concept of stress relief through load deflection. The two systems-EquiAdvance Cave, and PressureArch Panel Mining-are complementary. The objective of the former system is to provide relief from lateral stresses through advance caving and in the process also to achieve higher extraction at depth. Where surface subsidence cannot be allowed, the alternative PressureArch Panel concept is utilized to provide stress relief and moderately high extraction ratio. Both systems have been under trial for over three years and, together, produced over three million tons of copper ore. These two systems, and their production test results to date, are described.

Jan 1, 1977

By R. Larry Grayson

A menu-driven, linear-programming- based, user friendly computer program was developed to assist mine managers in determining optimal longwall panel dimensions for a given set of operating conditions. A sensitivity analysis must be performed by varying key mining and configurational parameters over an expected, practical range during the optimization process. Results from analysis of a base case mine indicated that no single combination of longwall panel length and face width is optimal for all operating situations. Each mine manager must therefore look closely at his operating situation and determine the proper dimensions to minimize total mining cost.

Jan 1, 1989

By Carol Cox Russell

More than two thousand abandoned mines within the Animas watershed in Southwestern Colorado are being prioritized for remediation by the Animas River Stakeholders Group (ARSG). Phased collection and assessment of information progressed from large scale to site specific. Prioritization was based on existing or potential environmental impact and technical feasibility of remediation as measured by dissolved Cd, Cu, and/or Zn in the discharge; indicators of habitat degradation; aquatic life in streams; cumulative impacts at the point of compliance; cost effectiveness; treatiblity/feasibility; and cultural and historic preservation.

Jan 1, 2000

By Bill Morgan

This paper discusses the economic zones of application for several different types of earthmoving equipment: dozers, wheel loaders in load-and-carry applications, wheel tractor scrapers, articulated trucks, rigid-frame trucks and wagons. Only the medium to large pieces of equipment were considered. From this chart (Figure 1), you can see the size range, in tons of carrying capacity, of Caterpillar equipment and the specific models analyzed.

Jan 1, 1994

By Felipe Calizaya, Sekhar Bhattacharyya

Mechanized underground mines suffer from noise overexposure. Noise levels are often above the Permissible Exposure Limit (PEL) where underground fans are used. Sound levels in active workings can reach up to 121 A-weighted decibels (dB(A)), especially when fans are not equipped with silencers. Use of silencers seldom ensures PEL. Overexposure of noise induces permanent hearing loss among mine workers. A NIOSH-funded research project and field studies at six coal and non-coal mines revalidated the findings. The University of Utah undertook laboratory studies to reduce fan noise at the source. A new silencer prototype with varying noise dampening material was designed and tested. The silencer and associated extension can be repacked with different dampening materials. The silencer and the extension were used in various configurations. Attempts were also made to simulate field conditions. The tests demonstrated a maximum sound level attenuation of about 14 dB(A) at the fan discharge. A properly designed silencer offers lesser resistance and thereby better fan performance and lower energy cost. The re-packable silencer is more likely to be maintained properly. Lowering of noise level happens in audible frequencies (4000 to 8000 Hz) which are important in A-weighting.

By Thierry Coléou

In this paper, we consider open pit optimization. At present, most methods specify the economic parameters and then find the corresponding optimal pit. But as the economic environment varies (which it does regularly these days), the "optimal" pit changes and quite often changes markedly. The questions are: by how much does it change and which parameters are most influential? The functional approach of Technical Parameterization of Reserves, devised by Matheron in 1975, gives the set of all the different optimal pits, under any economic condition. It separates technical design and economic assumptions and thus permits the use of several optimality criteria when choosing the final pit, and not just the maximization of an additive profit formula. Very efficient specific algorithms are presented to obtain all the potentially optimal pits. Fluctuations in the parameters induce changes in the optimum design. Inclusion relations that exist generate very tight bounds and hence very quickly detect optima, even when using a classical adaptation of maximization techniques (graph theory, moving cone, dynamic programming ...). The advantage of Technical Parameterization of Reserves over other methods is that it provides a nested sequence of optimal pits which can then be used for mine scheduling. Many possible mining schedules can be obtained by using the family of technically optimal projects to split up the orebody. The "optimal" schedule, which is in fact a compromise between the different requirements of the economists, the mine planner and the metallurgist, can be chosen from within the wide scope of possibilities. A practical example of mine scheduling for a chromite mine is presented in detail.

Jan 1, 1989

By M. A. D. Azevedo

The effect of pulping reagents on the flotation de-inking of laser printed wastepaper was investigated with regard to the removal efficiency of toner and mineral filler particles for different pH values. These results show that caustic pulping causes the toner to be released from the fibers at larger particles sizes. On the other hand, acid pulping not only causes the toner to be released at smaller particles sizes but also increases the concurrent flotation removal of mineral filler particles. It was experimentally observed that the froth generation and stability during flotation were improved for acidic pH values.

Jan 1, 1997

By L. R. Stoiser

The mineral resource potential of the Los Bronces deposit was successfully evaluated by an intense, coordinated field program over a 37-month period (April 1978 - May 1981). This project was part of a much larger study to determine the economic feasibility of expanding the open-pit, mine-mill operation 10-fold to 80 kt/d (88,000 stpd). The resource project included more than 120 km (74 miles) of core drilling and 64 km (40 miles) of drill rig access way construction under adverse topographic and climatic conditions, detailed geological mapping, and other related activities. The Los Bronces deposit is composed of an earlier mineralized porphyry-type body intruded in part by a large complex of mineralized hydrothermal breccia pipes. The mineralization is hosted by intrusive and extrusive igneous rocks. Various stages of erosion, oxidation, leaching, and supergene enrichment of copper are present. Drill hole indicated geologic reserves are estimated at 1.3 Gt (1.4 billion st), averaging 0.81% copper and 0.016% molybdenum at a cutoff grade of 0.6% copper equivalence decreasing to 0.25% over the life of the mine. Trace amounts of silver are also present.

Jan 1, 1987

By Brian Kenner, Peter Swanson, Todd Krahenbuhl

NIOSH has developed an automated PC-based seismic event (induced earthquake) monitoring, system for use in mine ground control studies. The distribution and coordination of data acquisition and processing functions across a local area network is a central feature of the system. Mine-wide installations utilize multiple, autonomous seismic networks located both underground and on the surface. Seismic event locations, magnitude estimates, and other processed data are distributed for display and analysis on network nodes both underground and in the offices of mine engineers and managers. This paper describes the system's design philosophy, hardware and software components, examples of installations, and a few observational results.

Jan 1, 2002

By S. C. Suboleski

Forecasts indicate that the acid rain bill currently before Congress is likely to cause an increase in demand of 30 to 40 million tons per year of compliance quality coal from Central Appalachia. This represents a doubling of this segment of the coal business. This paper will examine how this doubling can be met, what the likely implications for pricing are, the major uncertainties associated with these predictions, and the likely outcomes of the growth in compliance coal. Finally, some implications for fuel planners will be discussed.

Jan 1, 1993

By R. K. Mehta

A review of the literature reveals that methods for simulating the coupled behavior of size reduction and liberation are limited to binary mineral systems containing one composite particle class. The aim of this paper is to describe the development of a mathematical model to simulate such behavior for binary and ternary systems containing multiple classes of composite particles. A modified Levenberg-Marquardt algorithm and a finite difference Jacobian are used in conjunction with the developed model and a set of constrained equations to estimate all kinetic parameters. This estimation scheme is validated for a binary ore (sphalerite-dolomite) with five composite particle classes using experimental data.

Jan 1, 1989

By R. A. Metz, James W. Clark, William C. Dixon, Kevin L. Wiley, Thomas R. Couzens

This paper is a description of certain geologic aspects of the Inspiration mining operation. It is not a geologic description of the Inspiration deposit nor an exposition of all the geologic work involved in the development and exploitation of the deposit. A few specific examples of the application of geology and geostatistics to the mining process are given to illustrate the progress that has been made in making the Inspiration Mine more efficient and cost effective, and a statement of the philosophy of geologic applications is offered.

Jan 1, 1992

The concept of optical basicity is now being widely applied to rationalize and predict the chemical properties of slags. It employs signals from a probe ion to indicate the "state" or relative "freeness" of the oxygen ions in the slag, and hence provides a fundamental measure of slag basicity. Values of the bulk optical basicity of a slag can either be measured spectroscopically in samples of transparent solid glassy slag, or calculated very simply and accurately from the chemical composition of the slag. The way in which these values vary in different systems are illustrated as isoptical basicity lines on ternary diagrams, and the patterns obtained are discussed. The difficulties associated with assigning optical basicities to the oxides of transition elements are also reviewed briefly. It has been demonstrated that these bulk values can be used as the basis of a flux control model for steelmaking to achieve end-point chemistries much more reliably. Furthermore, several correlations have been established which allow the prediction of the slag-metal distribution of various solute elements. This approach has been used to predict the phosphorus distribution at the end of steelmaking, and also to custom design fluxes for the ladle and tundish to aid in the control of residual elements in the steel such as suphur, hydrogen and nitrogen.

Jan 1, 1990

By D. Sinha

Mine investment decisions involve both objective and subjective criteria. The subjective criteria are efficiently decided by interaction with company experts. The Expert System approach can incorporate knowledge of experts and interact with conventional computer programs on mine evaluation. Artificial intelligence offers considerable opportunities in comprehensive mine investment decision making process.

Jan 1, 1998