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By G. E. Karantzavelos

A novel two-stage froth flotation process for the recovery of pure magnesite from low grade ores is described. The process consists of a first-stage, magnesite flotation step where a rougher magnesite concentrate is floated with amine collectors. The first-stage froth concentrate is then repulped in fresh water, and quartenary ammonium salt and fuel oil are added to float the remaining impurities. The results from laboratory batch tests show that a high-grade magnesite concentrate assaying 0.99-0.20% Si02 and 2.84-0.46%a Ca0 can be produced. Regulation of the variables controlling magnesite froth flotation also allows the variation of the ratio % Ca0: % SiO2, between the acceptable limits 0.32 to 5.79. This ratio is important to the quality of dead-burned magnesite.

Jan 1, 1985

By James W. Harrower, Gerald S. Ball

This paper discusses the installation of steel linings in vertical, raisebored openings. Design criteria used to evaluate the applicability of liner type and design are presented as well as a brief description of installation procedures. Specific projects completed by J. S. Redpath Corporation are then outlined noting special considerations and techniques.

Jan 1, 1985

By Madan M. Singh

Increasingly, geotechnical data are being collected for various types of coal development projects. In many cases, a specific design concern is addressed. However, many data collection programs are not intended to immediately support mine design activities or to resolve a specific concern. The following discussion describes some current geotechnical approaches in mine planning, development of reserves, and peripheral activities. Types of Data Collection Programs Geotechnical data collection is increasingly becoming a part of standard coal exploration programs, performed along with stratigraphic evaluations and coal quality tests. The aims of such programs vary. The purpose of the exploration may be to fill out the portfolio on a block of reserves that is to be sold, leased, or held for potential future development. In such a case, a generic suite of geotechnical data are collected. The resulting engineering reports may touch on the more well known mining problems of the area, but detail may be lacking. The geotechnical data are mostly intended to enhance the saleability of the package. Mine design alternatives are generally not addressed.

Jan 1, 1985

Contents

Jan 1, 1985

By R. L. Amelunxen

"In January 1983, Gibraltar Mines Ltd. started an exploratory program on Column Flotation with hopes of improving performance of the Molybdenum Cleaning circuit. The encouraging results led to a column test trial in the Bulk Copper Cleaner circuit where the test unit has per¬formed well. A program was undertaken to understand the mechanics of column operation. A year and a half later, Gibraltar is considering the replacement of existing Bulk Copper and Moly Cleaning flotation cells with a fully computer con¬trolled Column Flotation circuit.BRIEF SUMMARY OF TESTWORKInitial testwork was done with a home made 20 inch diameter x 31 foot high column, equipped with a doppler flow-meter at the tail line and automatic level conrol. This loop maintained constant level in the column by throttling the tail valve. This column was placed in a variety of locations around the Moly circuit as shown on Figure 1 a, b. Test re¬sults indicated that the column could achieve much higher grades than the conventional cells, but recovery wise, the performance was low. Spillages from overloaded pump boxes were a common frustration during this time.Column control strategy was reviewed; and, in light of information received from McGill University, changed to conform with the methods that had been employed by D. Wheeler, of the Column Co. of Canada4 and Gaspe Copper Mines3.The column was tested replacing a portion of the bank, figure lc. The results obtained were more or less equal to the circuit. However, as we had Nitrogen gas connected to the column and not the regular cells, the column was kept in service. With the use of Nitrogen in the column, the usual copper depressant, Sodium Cyanide could be replaced with Sodium Hydrosulphide, hence lower operating cost.As time went on, a 10 inch diameter column was added in series to re-treat the concentrate of the 20 inch diameter column with hopes that the copper content would decrease from 0.6% down to 0.3% in order to save on subsequent leach¬ing costs. So far, results indicate there has been some im-provement, hut we are not achieving 0.3% copper. (See figure 1d)."

Jan 1, 1985

By John R. Bartels

In laboratory testing, the Bureau of Mines established criteria by which common resin-grouted roof bolting systems can be evaluated and compared. Ultimate strength and stiffness were determined for nonten-sioned full-column, point-anchor, tensioned full-column, and debondable resin-grouted bolts, and for variations on full-column boltsn Bolt per-formances were compared using the performance of the 3/4-in full-column resin-grouted bolt as the standard. New and innovative systems can also be qualitatively compared against this standard. Since the medium into which a resin-grouted bolt is installed is one of the most important parameters affecting bolt performance, various host mediums were used in the testing: sandstone, concrete, simulated coal, simulated shale, and plaster. Bolt performances expected in other mediums can be inferred from the response patterns obtained in these mediums. Results indicate several functional differences among bolt types. Where resistance to shear is important, point-anchor bolts may outperform nontensioned full-column bolts at a lower cost. In medium-to soft-strength rock, tensioned full-column bolts perform best. Also, varying the resin-steel ratio seems to have little effect on the properties of a full-column bolt, when proper resin mixing is ensured.

Jan 1, 1985

By R. P. Gardner

Results of work on the development of a phenomenological model for the continuous flotation process using short-lived radioactive tracer techniques for the determination of 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 state (CFFS) model has been derived and investigated. The short-lived radioactive tracer techniques necessary to extract the model parameters have been developed as have the necessary nonlinear search methods. The conditions under which all the model parameters can be extracted from a single radiotracer experiment are detailed and illustrated. A microcomputer-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 system for the two systems mica ore and coal.

Jan 1, 1985

By Al Sylvester

The drill-and-shoot excavation of the two underground Pumphouses for the Metropolitan Sanitary District of Greater Chicago's Mainstream Pumping Station is described. The construction sequence involved the concurrent excavation and support of the two 19.2 m (63 feet) wide by 83.6 m (274 feet) long by 29.3 m (96 feet) high caverns. Excavation was interrupted after taking the 6.1 m (20 feet) high top heading in order to cast-in-place a 0.2 m (8 inch) thick by 19.2 m (63 feet) wide concrete arch. The remaining 23.3 m (76 feet) of rock was then excavated in benches below the concrete arch. PROJECT DESCRIPTION Twenty-four kilometers (15 miles) southwest of the city of Chicago, Peter Kiewit Sons' Co., in a joint venture with John F. Shea Co., and Kenny Construction Co., has successfully completed the construction of the Mainstream Pumping Station for the Metropolitan Sanitary District of Greater Chicago. The five year, 169 millon dollar project is a vital component in Chicago's Deep Tunnel and Reservoir Plan in that its function is to lift the sanitary/ storm sewage back up to grade from 107 m (350 feet) below ground, and pump it to the treatment facilities 8 km (5 miles) away.

Jan 1, 1985

By Jack A. Caldwell

Jan 1, 1985

By J. Duncan Crone

"A test surface Pulse EM(PEM) survey over a plunging massive sulphide lens, located in the Snow Lake area of Manitoba, has shown that it is possible to detect the body to a depth of 300 metres. Another surface survey in the Athabasca basin of Saskatchewan, clearly outlined a large, basement graphitic zone below 450 metres of sandstone cover. Deep detection of these conductive bodies was achieved by energizing large volumes of ground with a strong transmitted EM field. Such large fields also energize all other conductors present in the exploration area. Both of the above survey results indicate that more than one conductor is present. In such cases, detailed field coverage is required for accurate interpretation, and interpretational procedures that assume simple geometrical shapes should be applied with caution. In all cases geological and geophysical information should be coordinated in detail. The first test drill hole still has a high risk of missing the deep conductive body and two or three holes should be budgeted per target.Borehole Pulse EM surveys are now routinely used to help zero in on deep conductive targets. They are also proving effective in development drilling programs by outlining the edges of conductive bodies. The results of surveys from northern Quebec illustrate how they may provide more accurate shape and tonnage estimates."

Jan 1, 1985

By R. D. Brown

This paper profiles Canada’s current economic, tax, and political environment with respect to its mining industry. Problems that must be overcome if the industry is to attain its full growth potential and are highlighted, some suggestions reflecting the opinion of many in the industry are given. Tables provide some detail on the current Canadian mining tax system, province by province, as well as for the Yukon and Northwest Territories, plus some relevant economic trends.

Jan 1, 1985

By Richard L. Rains

The 15,770-acre Worm Creek Roadless Study Area is in southeastern Idaho about 8 miles (mi) west of the northern portion of Bear Lake. U.S. Bureau of Mines personnel examined the roadless, area during the summer of 1984. No mineral resources were identified within the study area. There were no mines or mining claims in the study area in 1984. However, the study area is blanketed with oil and gas leases, but no known productive horizons have been identified within nor nearby. The roadless area is in the Cordilleran fold-thrust belt and is underlain by Paleozoic and Mesozoic marine strata more than 50,000 feet thick. The trace of the Paris thrust fault is 2 to 3 mi east of the study area and has an eastward displacement of about 4 to 7 mi.

Jan 1, 1985

All photographs by Carlos Pais Pictures only.... no script.

Jan 1, 1985

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 H. A. Schnell

"The Phase I Mill at Cluff Lake in northern Saskatchewan was designed to accommodate a very specific high grade uranium ore. As this high grade ore was depleted, construction was undertaken on a new mill circuit (Phase 2) to process a more conventional lower grade ore deposit.The Phase 2 Mill expanded the ore throughput to 800 tonnes per day. The new process employs crushing, grinding, leaching, counter—current decantation, solvent extraction and magnesia yellowcake precipitation and drying to produce a yellowcake concentrate.This paper discusses the process decisions required for this expansion and outlines the new mill circuit. Included is a review of the start up in August, 1984.1.,INTRODUCTION The Cluff Lake Uranium deposit is located 720 kilometers north of Saskatoon in northern Saskatchewan. A high grade deposit was discovered in 1970 with the first production taking place in 1980 after lengthy hearings. The original mill (or Phase 1 Mill) was specifically designed to accommodate this very high grade ore for a very limited plant life.Pilot plant work was carried out in 1981 on the other lower grade ores found in the immediate Cluff Lake area. Feasibility and process selection studies were then undertaken as the Phase 1 mill was nearing its end of life. These studies were completed in March 1983 when approval was given to construct the new Phase 2 mill."

Jan 1, 1985

By William H. Pomroy

The potential for large-scale fires in underground fuel storage and fuel transfer areas prompted the Bureau of Mines to study fire hazards in these areas and devise improved fire safety technology for use in these areas. This report describes the Bureau's research to characterize and quantify fire hazards in fuel storage and fuel transfer areas, develop guidelines for safe and efficient fueling system design, prepare specifications for automatic fire sensing and suppression systems for these areas, test prototype systems in the laboratory and in underground mines, and perform cost-effectiveness evaluations of the devised technology.

Jan 1, 1985

By C. G. Snavely

Martin County Coal Corporation produces coal from seven continuous miner sections in two coal seams which are often interlaced with rock partings. Because of high clay content and coal oxidation, all minus 100 mesh material is discarded in the preparation process. We began experimenting with various drum lacings on continuous miners in 1983 to improve product size consist and increase machine cutting rates. To date, + 6.35 mm material has increased from 61 to 73% of mined product, minus 0.15 mm material has decreased from 6% to 4% of product, and machine cutting rates have increased by 50 percent.

Jan 1, 1985

By P. Mousset-Jones

The USBH Mining Systems and Ground Control Generic Research Center funded a project leading to the improved planning of airflow and refrigeration in underground mines experiencing hot working conditions. The project was broken down into approximately five phases: 1. Visiting some of the known hot mines in the U.S. and sending out a questionnaire to determine other mines which might be experiencing hot working conditions in the future. 2. Choosing two mines in which to conduct measurements to determine the insitu rock thermal conductivity and diffusivity, and comparing these values with laboratory determined values. 3. Investigating computer programs available for mine climate simulation, and testing these programs with case study examples from the two mines where the rock thermal properties were measured. 4. Considering improved ways of estimating the wetness factor and experimenting with the use of heat flux meters to more directly measure the rock heat inflow into the airstream. 5. Applying the results of these investigations to simulating the climate for future mine development and production areas at the two- mines. The project is approximately two thirds completed. At the time of writing, the insitu measurements at one of the mines are still being recorded. This paper will be describing the procedures and results of the insitu rock thermal property measurements, and give a brief description of some of the simulated results obtained for a mechanised cut and fill stope case study from the Homestake Gold Hine in South Dakota.

Jan 1, 1985

By N. Melnyk

"FOREWORDThis paper provides a unique description of a method devised for mining a very thick steeply dipping seam of soft gassy coal which was prone to spontaneous combustion. The editors con¬sider that the information in this paper should be important to those who may have to consider mining such seams again at some time in the future and therefore believe that the paper warrants reprinting in the present volume. The author was ask¬ed to review the paper and to add any additional relevant in¬formation. He provided the accompanying footnote, only a month before his death on April 22, 1982.IntroductionIn the past, the Cadomin Coal Company has opened four mines, all in the same coal seam or its folds. Three of these were opened from river level by horizontal entries or rock tunnels. and the fourth, the present working mine, by vertical shafts. This paper deals largely with some operating phases of this fourth mine, with which the writer has been associated.The seam worked here is a thick, steep, bituminous seam, and the writer feels there is a paucity of published data on the mining of such seams. Possible reasons for this are that such seams do not lend themselves to intensive development or mining, there is little chance to mechanize because of the extreme pitch, and operations are fraught with many problems. In addition the present operations in this particular' seam are being carried on at a level below the former workings, introducing new problems, not encountered on the upper level.Coal will, without question, long continue to be an impor¬tant factor in the national economy, and some of the best coal is to be found in thick, steep seams. But with the exhaustion of the easily-mined coal near the outcrops, future coal will have to come more and more from lower levels. At Cadomin there is still considerable coal on the second level, below the old river-workings, and there is a possibility that, in the future, still lower levels will be worked. It is the purpose of this paper to indicate some phases of such lower-level operations and to invite discussion."

Jan 1, 1985

By R. C. Kadyk, C. J. Bise

High-voltage cable couplers are convenient and widely used accessories in modern coal-mine power distribution systems to help extend and retract power-feeder cables throughout a mine. Coupler design has tried to keep pace with the industry's desire to move to higher distribution levels, but the increase in recorded failures of 15-kV class couplers, which serve the 12.47-kV and above distribution levels, has inhibited this transition. Problems associated with the effects of partial discharge on high-voltage cable couplers are analyzed. The phenomenon of partial discharge is discussed, a testing standard is developed, and various coupler designs are subjected to its requirements. An analysis of test results and results based on field applications are provided.

Jan 1, 1985