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By S. P. Singh

Drifts are an integral component of underground mining. They provide access for men and material, means for transporting ore and rock and serve as air passageways. In view of their importance on the overall safety, economy and productivity of mines, empirical guidelines for controlled blasting design in drifts have been developed in this study. The application of the proposed concept was described by generating blast hole patterns for a mine with the help of a computer program. The mechanism of blast damage and the need for controlled blasting to alleviate ground control problems in underground mines have been outlined in this paper. The economic analysis between normal-and controlled blasting was performed based on the information from an operating mine. In addition, the review of drift blasting practices and problems in Canadian mines was also carried out in this study.

Jan 1, 1990

This paper reviews the development and operation of a small underground tin mine in NE Tasmania. Tin mineralisation was discovered in the Lottah area in the 1880's with early alluvial and eluvial workings leading to the development of large low grade open pit operations. Apart from short lived activities operations ceased in 1915. Intensive exploration in 1978-81 outlined substantial tonnages of low grade tin mineralisation (0.2% Sn) of open pit material. An underground ore body was also located (800 000 tonnes 0.6% Sn). Spectrum Resources Australia Pty Limited acquired a 98 percent interest in the property in 1988. Mine and mill development began in early 1989 based on an underground mine utilising trackless mining using room and pillar with fill stoping. The milling circuit involves primary jaw crushing, Barmac secondary crushing to lmm, Mogensen and DSM screens with jigs and tables to make a wet concentrate. Final tin concentrates are produced by high tension and magnetic separation. Planned production rates are 500 t/day with a mine life of 6-7 years.

Jan 1, 1990

By Joseph E. Worthington

The announcement of a high-grade ore intercept near Wenatchee, Chelan County, WA, by Asamera Minerals in 1983 triggered widespread interest in this old gold mining district. The district has a long history of exploration and production and was actually one of the few underground gold mines that operated in the post World War I1 years in the US. Gold occurs in a north-trending structural zone in folded and faulted Eocene arkose intruded by andesite and dacite dikes having dates in the 42 to 50 m.y. range. Ore has been mined selectively from ladder veins perpendicular to the trend, from the south end of the trend near Squilchuck Creek. These veins narrow and silicification becomes pervasive northerly where wider zones were caved later in the operation. Recent discoveries at "B" reef at the north end are also in wide zones of silicified arkose. The gold lodes originally cropped out as prominent silicified and iron-stained ridges that were described in the early days as "reefs." The early discoveries were made in out- crop about a hundred years ago, and two claims, the Gold King and Macbeth lodes, covering the most prominent out- crops on the north side of Squilchuck Creek, were staked in 1885 and patented shortly thereafter. A five stamp mill was erected in 1894, but failed to liberate gold for amalgamation. The two patented claims were acquired in 1934 by J. Keegan, who carried out limited exploration and shipped small amounts of flux ore to Tacoma during the next few years. There was no substantial exploration or development of the claims, however, for several years after that time, and ownership of the claims eventually passed to a series of trusts administered by a bank in Seattle.

Jan 1, 1990

By Robert B. Parsons

"Effective January 1, 1990, mines in British Columbia are subject to a new provincial mining tax statute, the Mineral Tax Act. Under this Act, mines are subject to a two-tier tax system, with a minimum tax payable on ""net current proceeds"" and a higher tax paid on net income. For many mines, the present value of tax paid under the new rules should be comparable to the amount paid under the old rules. Earlier cash payments could pose difficulties, particularly for smaller mines, but existing producing mines could benefit in the short-term.IntroductionEffective January 1, 1990, British Columbia has replaced the provincial mining tax regime under the Mineral Resources Tax Act with a new system under the Mineral Tax Act. The new rules borrow some ideas from other provinces (New Brunswick's two-tier concept, and Saskatchewan's indexed costs) with a view to levying a tax that is fairer to both the producer and the province."

Jan 1, 1990

By Pierre Sauvé, Guy Perrault, Armand Savoie, Pierre Trudel

"La Mine Doyon est une entreprise détenue à parts égales par Cambior Inc. et par Minerais Lac Ltée qui en est l'opérateur. Les statistiques de production au 1"" janvier 1990 indiquent que, depuis le début de son exploitation (1980), 10.3 Mt de minerai d'une teneur moyenne de 5,9 g Au/t ont été usinées. Les réserves sont estimées a 10,4 Mt à une teneur moyenne de 6,6 g Au/t jusqu' à une profondeur de-450m.Trois zones minéralisées sont présentement en exploitation. Ces zones sont caractérisées par la présence de veines de quartz-pyrite accompagnées localement de chalcopyrite. Les roches encaissantes sont les schistes a séricite (zone# 1), les roches volcaniclastiques de composition felsique (zone #2) et intermédiaire (zone #2, zone ouest) ainsi que les roches intrusives appartenant au pluton de Mooshla (zone ouest). Toutes ces roches ont subi un métamorphisme régional dont l'intensité correspond à la limite supérieure du facies schiste vert ( -425°C}.Les zones minéralisées sont situées à I' intérieur des zones de déformation et d'altération les plus intenses. L'étude des structures mineures nous indique que la région a subi plusieurs épisodes de déformation ductile a fragile qui sont antérieurs, contemporains et postérieurs al a minéralisation. L'analyse structurale indique également que la déformation majeure est associée à une importante phase de compression orientée N-S a NNE-SSW.L’ensemble des observations suggère que la minéralisation et I' altération associée sont de type épigénétique. La mise en place du minerai se serait effectuée à la fin de l'épisode principal de métamorphisme et de la déformation."

Jan 1, 1990

By Steve Kral

Competition in the gold mining industry throughout the world has become fierce in recent years. The challenge facing operations personnel is to produce more gold for less money. Likewise, the explorationist's charge is to find more gold in a more cost-efficient manner. That means using new technology to find new gold deposits and expand present ones. More accurate mapping instruments are available to geologists in the search for new deposits. Advanced geophysical and geochemical methods enable explo¬ration teams to review previously mined districts in their search for minable reserves. Four technical sessions on the geology, exploration, and development of gold deposits were part of the program at `world Gold '89,' a Gold Forum on Technology and Practices," held by SME and The Australasian Institute of Mining and Metallurgy in Reno, NV, Nov. 5-8, 1989.

Jan 1, 1990

By P. M. Lin

This paper presents an overall stabilization method to eliminate the potential of reoccurrence of subsidence over abandoned mine lands. The method considers column grouting at the specific locations inside the subsidence influence areas including the distressed and stress concentration zones instead of grouting' around and beneath the damaged structures. The later method is commonly used for AML subsidence abatement at the present. By using finite element method the conditions of stress distribution in the strata before and after grouting can be calculated. The design of grout pattern includes the location and number of the grouting holes. Based on the calculation, the proposed method significantly reduces the stress concentration, i.e., the potential of reoccurrence of subsidence can be reduced or eliminated. A comparative analysis including number of grouting holes, grout affected area, stress level, and potential of subsidence reoccurrence will also be presented.

Jan 1, 1990

"The Pierre Beauchemin Mine attained commercial production in January 1989, and went on to produce 23 968 ounces of gold for the year, 3% higher than forecast. Underground development was accelerated to prepare the way for the production of an estimated 40 000 ounces in 1989.IntroductionThe Pierre Beauchemin Mine is located nine miles west of the city of Rouyn-Noranda (Fig. I).As a result of the amalgamation with Sullivan Mines in October 1987, the mine is now entirely owned by Cambior Inc.The Eldrich deposit was discovered in 1953and began production in 1955, closing in 1962 following the decrease in gold prices and the simultaneous decrease in silica content in the ore, which was sold to the Noranda smelter for flux. A total of 717 000 tons grading 0.14 oz Au/t were produced during this period.From July 1984 to October 1987, an underground exploration program was carried out by Sullivan on the Eldrich mining concession and the nearby Flavel property. The first phase of the program included reinstallation of surface facilities and dewatering of the Eldrich Mine. Following the completion of the first phase, extensive exploration was carried out, including a major program of diamond drilling. It was then decided to deepen the shaft to a depth of 1800 ft to access a new zone called the No.5 Zone .Following the amalgamation with Sullivan in October 1987, Cambior assumed the role of operator for the project, and continued the shaft deepening work that had already been started. A feasibility study was completed in April 1988 and the Cambior board of directors approved a production decision for the Eldrich-Flavel project.The preproduction program extended from May to December 1988 and was aimed at preparing the stopes in the upper part of the mine and at developing the mine infrastructure at the bottom of the mine.The mine was officially opened in August 1988. Cambior renamed the project the Pierre Beauchemin Mine in recognition of Pierre Beauchemin's pioneer-work."

Jan 1, 1990

By L. B. Phelps

This paper focuses on the use of an integrated mine planing software package entitled "REMINE" which was constructed to provide a project evaluation tool for analysis of remining projects. Coal remining constitutes the affecting of sites which have had a past history of mining and have a pre-existing pollutional discharge. Such sites require a Best Professional Judgement (BPJ) analysis. The program was written to provide such an analysis with flexibility in the mine plans which can be analyzed. The process required for a BPJ analysis will be detailed and mine plan simulation performed to demonstrate the analysis.

Jan 1, 1990

By J. Platt

Debate over acid rain legislation has presented a moving target for coal and utility company planners attempting to figure out how legislation will affect their business environment. In spite of disagreement among experts, the prospect for continued change, and persistent --perhaps even growing --uncertainty, a great deal has been learned about coal market dynamics. This paper reviews progress and describes some of the major problems and controversies.

Jan 1, 1990

By Demin SS

Slow seismotectonic movements along the in-clined deep fault zone under the compressional horizontal stresses are supposed to be the prin-cipal mechanism controlling the structure and processes in the active ocean margins. Within the scope of the plane strain problem a simple 2-D geomechanical model for the evolution of an island arc system is investigated. We consider a homogeneous elastic half-plane with a shea-ring surface crack. The key element of the model is viscous interaction between the crack sides, the viscisity varying with depth. The model dif-fers from the classical steady-state mode of subduction by nonstationary creep processes on deep faults and by possibly cyclical development of the transition zone.A numerical modeling of the stress-strain state within the island arc system through time was carried out using a semianalytical approach. The results of simulation are in good agreement with geological, geophysical, and seismological data.

Jan 1, 1990

By K. F. Unrug

A new testing technique for the determination of the rock strength from portable rock tester is proposed. It is a quick and economical method that can determine the rock strength with reasonable accuracy in different conditions. This method is based on the application of portable rock tester working at the principle of forcing steel ball into the rock surface. The correlation between laboratory measured compressive and/or tensile strength and rack tester reading has been determined in terms of the three-controlling parameters: (1). diameter of indentation &'the testing sample, (2). diameter of indentation-on the reference bar, (3). Brine11 hardness number of reference bar.

Jan 1, 1990

By Minglin W, Zhixing L

The laws of detonation wave velocity variation in propagation process along the charge under channel influence are investigated widely in this paper. The result is obtained by blasting experiments. Bore hole is simulated by plastic tube or steel pipe (with outer diameter 45 nun, inner diameter 40 or 41 mm). Blasting experiment is carried out with a cylindrical charge of 32 mm diameter. The author analyses the characteristics of energy distribution along the charge under above-mentioned conditions. Reasonable initiating position and initiating direction are also analysed. A double-direction initiating method which consists of several initiating charges is put forward. The blasting effect of this initiating method when used in underground mining is stated out.

Jan 1, 1990

By S. K. Kawatra, M. T. Rusesky, T. C. Eisele, D. X. Zhang

It has been observed in some mineral processing plants that grinding circuit efficiency varies seasonally, such as in some plants which are located in the northern US and Canada and undergo large seasonal temperature changes, with the grinding circuit efficiency different between summer and winter. This indicates that the temperature of grinding circuit slurry has a noticeable effect on grinding performance. The effect has rarely been studied. To this end, an investigation to examine the effect of changing temperature on efficiency and determination of the mechanism responsible has been carried out. Plant investigations and laboratory experiments have been conducted in order to study hydrocyclones. It was demonstrated that when the pressure drop is held constant, the d50(c) size decreased approximately linearly with increasing temperature, while the shape of the reduced efficiency curve remained nearly constant. This effect was determined to be due to changes in slurry viscosity with temperature.

Jan 1, 1990

By E. A. Pelczarski

Initially, the objective of this contract was to develop a PWSCSR that could meet proposed criteria (that were different from 30 CFR 11(Title 30 of the Code of Federal Regulation part II) and that would be less than twice the size and weight of a filter self rescuer. This objective was met. Consequently, the original contract was extended to develop a PWSCSR that would meet existing CFR-30 criteria within the same size and weight constraints. This resulted in the development of a PWSCSR (the SR-100) that received NIOSH/MSHA approval (TC-239). This report presents a historical discussion of the design and development of the SR-100 as developed by CSE Corporation under Bureau of Mines contract number H0368013. The technical parameters and the test results of NIOSH/MSHA 30 CFR 11 certification are also presented.

Jan 1, 1990

This paper will describe the exploration project which led to the discovery of the La Escondida porphyry copper deposit in northern Chile and will serve as companion paper to the description of the geology of Escondida being presented by J M Ojeda. The author would like to express his appreciation to Robert Hickman, Chairman of Minera Escondida, for permission to present this paper.In July 1978, a proposal was made by J D Lowell to Robert Wheaton, then Exploration Manager of Utah International, that Utah fund a "grass roots" program exploring for porphyry copper deposits in northern Chile. Wheaton expressed interest, and it was agreed that Getty Oil Co also be invited to participate. A joint venture agreement for the Atacama Exploration Project was signed January 1, 1979, between Utah, Getty and Lowell. The project was managed by Lowell who reported to a management committee which through most of the project consisted of Lowell, Francisco Ortiz, Robert Wheaton, Maurice Young, Sigfried Muessig and Louis Rove. Oliver Warin and Jim Bratt participated in the committee in the last phase of the contract. Special thanks are due Louis Rove of Getty and Maurice Young of Utah who made contributions throughout the course of the project. Francisco Ortiz was resident manager through most of the project.

Jan 1, 1990

By E. K. Albert

In 1977, Congress enacted Title IV of the Surface Mining Control and Reclamation Act (SMCRA), providing for an "abandoned ml.ne reclamation fund". This fund, taken from a fee collected from operating coal mines, provides capital for the reclamation process. However, given the number and extent of abandoned mine sites in some states, the question of project selection is important. This paper describes a project in progress to create a Management Information System application for project ranking under multiple objectives. The benefit of this project for the need of new environmental control technologies will be discussed.

Jan 1, 1990

By R. Sage, N. Rillette, M. D. Everell, G. Herget

"CANMET has been operating as a Government Technology Centre for two years. Many of CANMET's programs involve long-term research and require special expertise, often available at Canadian universities. CANMET's involvement with universities ranges from research grants and contracts to exchanges of scientists and joint use of research facililies. Examples of CANMET - university cooperation in mining are presented. IntroductionIn the last two years or so CANMET has undergone a significant metamorphosis, resulting in greater emphasis on applied research to enhance Canada's industrial capability. CANMET's new mandate is reflected in the types of projects undertaken and their categorization, (Fig . I). Emphasis is being placed on two project categories: strategic R&D, to enable CANMET to serve the changing technological needs of the industry; and incrernental R&D, to serve the more immediate industry needs through modifications to existing technologies and knowledge. The balance of CANMET's e ffor t is devoted to providing Mandated and Specialized Services, and to Exploratory Research.CANMET interaction with universities can involve one of several available vehicles : contracts, research grants, exchanges of scientists , student employment and nomination of professors on CANMET's advisory council. Instances of key university technical support to CANMET mining projects are highlighted."

Jan 1, 1990

By R. F. Hochstein, A. J. Neale, B. C. Flintoff

"Process control technology holds very significant potential benefits for many mineral and coal processing plants. The impact can be expected in terms of performance improvements (e.g. increased throughput, better quality control, higher availability), through reduced operating costs (e.g. lower reagent consumptions, manpower reductions) and in the form of intangibles (e.g. reduced vulnerability to manpower turnover, increased productivity in the user group). However, the installation of a process control system will represent considerable capital expenditure and will generate an operating cost. No management team would approve the funding for such a project without some reasonable measure(s) of the profitability of a proposed system. This paper describes a methodology for addressing the justification problem. Of particular interest is the approach to quantifying performance improvements, frequently found to be the predominant benefit of process control.INTROPUCTIONProcess control has become widely recognized as an essential component of any processing operation. It has direct impact on productivity, process efficiency and product marketability. The reported pay backs associated with successful installations underscore this observation. As a consequence, many operators who have little in the way of process automation are looking to initiate control projects, while those who currently enjoy some level of automation are looking to upgrade existing control systems (= process + instrumentation + hardware + software + operators + support). While the emphasis here would appear to be on retrofit process control projects, new plants, or those currently in the design stage, will usually find themselves in one of these categories shortly after startup 1."

Jan 1, 1990

By William A. Fuchs

A study of carbonaceous ore at the Santa Fe mine (Corona Gold Inc.) shows that there is no quantitative relationship between organic carbon content and preg rob, although much of this material preg robs. However, there is a relation between K20 and preg rob. Preg rob generally occurs only in those samples with greater than 2% K20. X-ray diffraction and chemical . studies show that the critical factor is the illite content of mixed (possibly interstratified) illite-smectite. Apparently illite, at a certain threshold, "geo-activates" the carbon. The potential for easily monitoring preg rob using a gamma ray spectrometer is discussed.

Jan 1, 1990