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By Charles Hart

A STUDY of the various ores that have been discussed impresses one with the need of beneficiation, in many cases. This applies to the ores that have lain dormant, due to necessity for further preparation, or to ores that now find a market due to a changed condition. Processes of beneficiation will come into their own as our richer ores become exhausted. Many efforts at improvement have been commercial failures, due to prematurity. Thomas A. Edison, with characteristic foresight, attempted concentration of the low- grade New Jersey magnetites some thirty years ago. Due to high costs and the discovery of the Mesabi range, his efforts were futile. However, a successful crusher, designed by Mr. Edison, resulted from this attempt. Agglomeration of concentrates had not, at that time, been brought to its present efficiency, when sinters and briquettes of excellent physical condition are obtainable. Recent efforts in the beneficiation of the lean magnetites of the East Mesabi resulted in an excellent sinter, but that operation is also ahead of its time.

Jan 1, 1929

By E. L. BROKENSHIRE

FLUORSPAR, a little known non-metallic mineral, referred to technically as fluorite, chemically as calcium fluoride, is a compound of calcium and fluorine in the ratio of one molecule of calcium to two of fluorine. By weight it is composed of 51.3 per cent of calcium and 48.7 per cent of fluorine. Its specific gravity is 3.2. It is brittle, has a hardness of four and can be easily scratched with a knife. It weighs about 200 Ib. per cubic foot and has a melting point of 1650" F. The color of fluorspar ranges from pure white and opaque white, according to its purity, to various hues of yellow, green, pink, lavender, blue and brown, to bluish black. Although the lumps have color, when ground the fluorspar becomes pure white. The reason for this is because the mineral usually carries no fixed pigment, the color being produced by the re- fraction of light rays within the crystal structure and small quantities of organic matter which readily oxidizes. It crystallizes in the isometric system with perfect octahedral cleavages.

Jan 1, 1929

By O. A. Carson

Introduction Although the equilibrium conditions of the copper-tin alloys have been the subject of a ?great amount of research, the equilibrium diagram is still in doubt. The first systematic investigation of the series was made in 1894 by Le Chatelier, who published a freezing-point curve. In 1895, Roberts-Austen and Stansfield published the complete liquidus and partial solidus curves, which they modified somewhat in 1897. Their liquidus as given in 1897 is essentially that accepted today (Figure 3). Haycock and Neville also published a liquid us curve in 1897. In 1898, William Campbell published a series of micrographs showing the changes in microstructure which accompanied the thermal changes of Stansfield? s diagram. The classic work on the bronze series was published by Heycock and Neville in 1903. Their diagram was based on both thermal and microscopic evidence, and is the first for this series of alloys which can be considered nearly complete. Further, it was the first bronze diagram in which any attempt was made to apply the phase rule in the interpretation of the thermal and microscopic results. That portion of Heycock and Neville's diagram covered by the present work is reproduced in Figure 7.

Jan 1, 1929

By D. Harrington, F. E. Cash

For a number of years the efforts of the coal -mining industry , as well as of the Bureau of Mines , have been directed largely towards the limitation and prevention of explosions in coal mines . The origin of most explosions is ignition of methane or marsh gas , but the extent and violence of these explosions depend chiefly on the combustible dust present . The Bureau of Mines has conducted a large number of tests on the use of incombustible materials in limiting or preventing widespread explosions . The result of these tests , published in Bulletins 167 and 268 and Technical Paper 386 , proves that incombustible dust can be so applied and maintained in coal mines that the ignition of the mixture of incombustible and combustible dusts , or the propagation of flame by the dust mixture , is impossible ; on the other hand , experience and experiment indicate that watering methods are not reliable as a preventive of general or widespread coal-mine explosions . This report describes the use of " mudite , " a mixture of water and finely divided incombustible soil or dirt applied in some coal mines as a means of attempting to limit or prevent widespread explosions .

Jan 1, 1929

By S. R. Zimmerley, John Gross

"The investigation discussed in this paper was undertaken to obtain fundamental data on crushing and grinding and has been confined, so far, to work on quartz.The results of crushing or grinding have hitherto been judged entirely by the amount of the various-sized particles produced, based. on sieve sizing for particles above 74 microns in size and on microscopic measurement or elutriation for particles below 74 microns - a method which could give only a general idea of what had been accomplished.There was a distinct need of a ""yardstick"" for the measurement of crushed material. It appeared that no advance in the fundamental investigation of crushing and grinding could be made without a reliable method of surface measurement and that such a measurement would have to be based on some property of the surface of the crushed material.A number of attempts based on various surface actions, such as adsorption and heat of wetting, were made to measure surface on quartz particles, but all gave unsatisfactory results. After some preliminary work it was decided that a dissolution method based on Wenzel's law-- ""the reaction velocity between solids and liquids is proportional to the area. of contact""4 -- would be the most feasible.Early use of the dissolution method had been made for surface measurements5, and lately Dr. Geoffrey Martin and his coworkers in England used the dissolution method to determine surface on quartz. They compared the amount of quartz dissolved from a sample in one hour by a hydrofluoric acid solution, with the amountdissolved from a measured quartz cuboid6,After investigating the solvent power of sodium carbonate, sodium hydroxide, and hydrofluoric acid for quartz, hydrofluoric acid was selected as the most suitable solvent, and a dissolution method was developed which gives very reliable results.During the dissolution of quartz in hydrofluoric acid, the reaction velocity changes for two reasons: there is a change in concentration of solution, and a change of surface of the solid. The amount of quartz dissolved in a definite period of time is therefore not a true measure of surface. If, however, the reaction velocity or rate of dissolution for various periods of time be plotted, a curve will be obtained which, if extrapolated to the zero time ordinate, will give the rate of dissolution before any change of surface or any change in the solvent has taken place, and which is a true index of surface. This rate of dissolution, expressed in percentage of the original sample at the zero time ordinate, is designated herein as the ""Initial Rate"" or as simply ""I. R."""

Jul 1, 1928

By F. O. Willhofft

The symposium on mine safety held in connection with the annual meeting of the Institute three years ago, it. was pointed out that "at present no convenient, reliable, accurate means for determining the gas content of mine air is available, for use by the ordinary mine man." In a letter addressed to Coal Age and published on Feb. 25, 1925, Thomas T. Read, then Director of the Safety Service of the Bureau of Mines, stated: "It is to be hoped that sometime in the near future some-one will invent a reliable methane indicator that is con-venient to, use and will permit the keeping of all flames of every character out of bituminous mines, through doing away with the safety lamp." The Martienssen methane detector, which has re-cently received the official approval of the Bureau of Mines, is intended to. meet the demand for such an in-strument as expressed at that meeting and on many other occasions. The characteristics which qualify it for the task are the following: (1) simplicity; (2) small bulk and light weight; (3) ruggedness; (4) accuracy sufficient for the requirements; (5) safety; and (6) dependability. The principle on which the working of the instrument is based may best be explained by giving a brief out-line of the various stages of development through which the inventor, Professor Martienssen of the University of Kiel, Germany, advanced to the final solution of the problem which he had undertaken to solve.

Jan 2, 1928

By J. B. Mawdsley

Introduction The writer was instructed to visit the Chibougamau region during the field season of 1927 and report on the mineral discoveries that had been made there since 1911. lt was deemed advisable to obtain detailed information regarding the rocks underlying the area in the vicinity of these recent discoveries. Accordingly an area 60 square miles in extent was mapped. The outcrops were studied along the water courses and along bush traverses spaced at half-mile intervals between these water courses. The completion of the rest of the summer's programme allowed only three weeks for this work. lt is from this small, mapped area, and this necessarily cursory survey, that the material for this paper was obtained. Location And Means Of Access The name Chibougamau district is applied loosely to an ill-defined area of about 1,000 square miles lying mostly north and west of Chibougamau lake in the Province of Quebec. The lake is approximately half way between lake St. John and James bay. It lies 150 miles north of the Canadian National railway and 40 miles south of Mistassini?lake.

Jan 1, 1928

By C. A. Heiland

THE investigations described were made on a portion of Clear Creek basin near Golden, Colo. (A portion of the area under survey is shown in Fig. 1. The photograph was taken in the vicinity of station No. 2 of Line II.) Three principal purposes were in the minds of the investigators: 1. To repeat with modern, more sensitive and more reliable instruments magnetometric placer investigations previously made. 2. To disprove the recently advanced theory that deposits of the glacial period have no pronounced magnetic effects. 3. To develop in detail the theory of the magnetic effects produced by placer deposits. Six years ago, the first magnetic observations were published, which proved that it is possible to locate gold-bearing channels with relatively crude instruments.1 Two years ago, K. C. Laylander published results obtained with similar instruments.2 The measurements of the latter were discussed by the senior author of this paper.3 At that time, however, the material available for such a discussion was somewhat scarce and not made with the most modern magnetic instruments, although very brilliant results were obtained. Therefore, the senior author felt that magnetic investigations should be made on very clear geologic conditions with the most modern instruments.

Jan 1, 1928

By G. E. McElroy

When mechanical ventilation is to supersede the natural ventilation of a mine it is desirable to determine what resistance the mine as a whole offers to the flow of air in order to specify properly the limiting duties of a ventilating fan. The relation of pressure to volume of flow for the mine as a whole may be calculated from experimental data, or it may be determined directly by measurements of volume of flow and the natural draft pressures causing flow; but in both methods the determinations are affected by many variables. With the intention of making a practical application of both methods, a small metal mine in process of development at Butte, Mont., was selected by the writers as the object of experiments planned to compare the mine resistances determined by measurements of natural draft and volume of flow with those calculated from experimental data. Four sets of teats were made with natural draft in October, 1925, December, 1925, April, .1926, and September to December, 1926; the last set consisted of a series of weekly observations. DESCRIPTION OF MINE The mine selected for the experiments was a typical vertical shaft metal mine in the development stage. No stoping had been done, and ventilation was confined to shafts, crosscuts, drifts, and raises. Figure 1 is a dia¬grammatic sketch of the main openings. All were timbered with full sets on approximately 5-foot centers. The shaft compartments were 4 by 4.5 feet, and one in each shaft was partly blocked by staggered manway landings. A pump column in the upcast shaft was discharging about 280 gallons a minute of water at 70° F. from the 1,000-foot level. The drifts were slightly sinuous, but the crosscuts were exceptionally straight and uniform in area; both drifts and crosscuts were about 5 by 7 feet in cross section. The raises were composed of vertical sections joined by frequent 450 offsets; each had three 4.5 by 4.5-foot compartments, of which two were plank-lined ore chutes and one was partly

Jan 1, 1928

By J. D. Stewart

One of the first important questions that should be settled on the opening of a mine or the development of a new deep is the system of haulage to be used, since the layout of the haulage-ways at the pit bottom, or, in case of a slope mine, the arrangement of the surface works, depends largely upon the type selected. Should it later become desirable to install a system of haulage of a type other than that for which the mine roadways were originally laid out, considerable difficulty would likely be encountered in its installation and with the result that it would in all probability be most unsatisfactory and expensive in its operations. It therefore becomes very necessary that full consideration be given the haulage problem at an early date in order that the type best suited to the mine conditions and the required outputs can be intelligently planned for. It is sometimes found, however, that no matter how well the mining engineer explores the seam to be developed, or how accurately he anticipates its eccentricities, there will still remain some unrevealed or unsuspected conditions, or shall we say obstacles, placed by Nature to prevent the too easy winning of her treasures and incidentally to frustrate or modify the application of the plan so painstakingly laid down on paper, and to adversely affect the cost estimate.

Jan 1, 1928

By Louis Frost

The coal-mining industry of Nova Scotia, particularly of the island of Cape Breton, today faced as no other industry with economic problems calling for progressive engineering with production on an economic basis, must soon enter upon a phase of reorganization wherein all factors conducive to the cost of producing coal relative to the prolongation of the life of the collieries with the ultimate winning of the maximum submarine area must be closely reviewed. Bearing this in mind and applying the process of elimination to coal-mining costs generally, we are left with only three channels through which we may approach the problem of cost reduction in producing coal: (a) intensive mechanization (b) reduction in the cost of labour (c) reduction in the cost of materials. Assuming that mechanization has reached an economic stage and that labour costs have reached an economic limit, we must turn our attention to the general material costs, which may be classified as 'live' and 'dead' costs. The former take in all things which can be accredited with a fractional depreciation and written off the balance sheet over a period of years. On the other hand, the ?dead'costs-of which the cost of supporting the underground workings form part must be completely written off: for these, no return may be expected, other than the economic return in the reduction of the cost per ton of coal produced.

Jan 1, 1928

THE absence of any locality maps of the district of Morobe has been seriously felt by mining engineers engaged on the goldfields, and as it was evident at the beginning of operations that the administration would be unable to make good this deficiency, ascheme for making rapid traverses was worked out, and in all subsequent travelling the necessary records were kept for the construction of a reliable reconnaissance map of the Bulolo goldfield and its approaches (see Plate 1.). Since all the field work had tobe carried out without encroaching on primary duties, the compilation of sufficient data was a somewhat lengthy business. It was found that in this r;ough country a pedometer was useless, as it was impossible to calibrate it for the variation in length ofpace between climbing semi-precipices and walking over level country. Further, the native tracks "meander" so excessively that the only method of calculating air-line distance is by timing, and a knowledge of what the timing represents, and until a 10kg experience had been gained in the time taken to cover known distances in various types of-country, one could not feel competent to estimate sufficiently accurately. It was found that reliability could be attained only when walking at nearly top pace. Inregard to aeroplane traverses, results were reliable only when the air was fairly still.BEARINGSIn arriving at the bearing between main traverse points, the method used was to keep a "boy" about two chains- behind when marching and sight back on him, standing, at about two-chain intervals. These bearings were averaged into the field book at the end of the day, each line being averaged separately. As the roads became known, it was possible to get a considerable amount...

Jan 1, 1928

By C. C. Furnas

In the course of an investigation3 of the flow of gases through beds of broken solids the author obtained a number of data .on the specific volume of beds of broken solids of variously mixed sizes. A mathematical theory of the limiting conditions has been developed and some generalizations have been made for intermediate cases. A more definite knowledge of the relation between space occupied and size composition would be valuable to all those who are handling large quantities of broken materials. Such knowledge might be advantageously applied to the operation of a coke oven. For example, the output of the oven depends in general upon the number of pounds of coal which can be put in the oven at charging. It is known that the capacity of one battery of ovens was increased several per cent by slightly increasing the proportion of fine material in the charge.

Jan 1, 1928

By E. F. Kingsbury

ONE of the well-known and important uses of the noble or precious metals has been for electrical contacts. In fact, the elements of this group, comprising gold, silver and the six platinum metals, have been called "noble" because of their ability to resist- heat and corrosion, properties which were early found to be of importance in good contacts. Of these, platinum and its iridium alloys, palladium, and silver, have been extensively used. In recent years the electrical industry has been responsible for about one-eighth of the total consumption of the platinum metals in the United States. Information is not available as to what part of this one-eighth has been used for contacts but it is certainly an important one. SUBSTITUTES FOR PLATINUM During the past 20 years a considerable number of contact alloys have been proposed in the patent literature largely with the aim of more or less replacing platinum by gold or silver, and some of these alloys are finding increasingly widespread application as the reliability of their performance becomes established.. From even the partial data at hand it appears that this substitution by the less precious metals has replaced at least one-half of the amount of platinum that the entire electrical industry would otherwise be consuming at the present time.

Jan 1, 1928

By Etienne S. Bieler

Mr. Chairman, Ladies and Gentlemen, I come to you tonight distinctly as a physicist, not as a geologist or a mining man. My experience in applied geophysics has been short, and I do not doubt that many of you have a much larger acquaintance: with the subject than I have. A little over a year ago, the firm of Alderson, MacKay & Armstrong decided to investigate the possibility of developing a new method of electrical prospecting suitable to our northern Quebec and northern Ontario conditions, and asked me to take up the work. A preliminary survey of existing literature convinced me that the field of induction methods was most promising. I wish to give you some account of the work carried on last summer in the Rouyn district in this connection with the very able assistance of Mr. H. G. I. Watson. Geophysical methods of prospecting can be divided generally into four classes: magnetic, electrical, gravitational, and seismic. Each class depends on the existence of a definite property in which the valuable mineral to be discovered differs materially from the surrounding rocks. In the four classes, the property will be, respectively, magnetic permeability, electrical conductivity, density, and elasticity. By far the largest differences occur in the case of electrical conductivity, where it is not rare to find ratios of the order of several millions, or even billions, between ores, sulphide ores especially, and the surrounding rock. Hence the sensitiveness and delicacy of electrical methods. Of these four classes, only two, the electrical and the magnetic methods, have been put to extensive practical use in the discovery of metallic ores. The other two classes are important mainly in connection with oil detection.

Jan 1, 1928

By E. L. Martheleur

The use of electricity in coal mines dates almost from the time when it was realized chat it could be used to produce mechanical power. The first motor put in service underground was installed to drive a small pump nearly 40 years ago, and since then the use of electricity in mines has reached an extent undreamed of at that time. We now find its universal adoption in all the mining countries of the world. Great progress has been made in the development of mining electrical apparatus in the last decade, and excellent and adequate material is now available for the use of electricity underground. Although mining accidents, due to the use of electricity, are not frequent, the miner is justified in demanding chat all electrical apparatus for installation below ground be constructed with a greater degree of safety than that used on the surface. That this view is shared by the authorities of the different mining countries is evidenced by governmental regulations relative to the use, erection, and maintenance of electrical apparatus below ground. Those with which we are specially concerned are the regulations for the installation and use of electricity in the coal mines of Nova Scotia. The potential dangers of electricity in coal mines are: Shock or burns by contact from live parts. Shock or burns by contact with parts which, although normally dead, have become accidentally alive. Fire. Explosion of gas or coal-dust Explosion of apparatus.

Jan 1, 1928

By E. F. Kingsbury

ONE of the well-known and important uses of the noble or precious metals has been for electrical contacts. In fact, the elements of this group, comprising gold, silver and the six platinum metals, have been called "noble" because of their ability to resist heat and corrosion, properties which were early found to be of importance in good contacts. Of these, platinum and its iridium alloys, palladium, and silver, have been extensively used. In recent years the electrical industry has been responsible for about one-eighth of the total consumption of the platinum metals in the United States. Information is not available as to what part of this one-eighth has been used for contacts but it is certainly an important one. SUBSTITUTES FOR PLATINUM During the past 20 years a considerable number of contact alloys have been proposed in the patent literature largely with the aim of more or less replacing platinum by gold or silver, and some of these alloys are finding increasingly widespread application as the reliability of their performance becomes established. From even the partial data-at hand it appears that this substitution by the less precious metals has replaced at least one-half of the amount of platinum that the entire electrical industry would otherwise be consuming at the present time. While the subject is of considerable interest to the metallurgist it is , even more so to the electrical engineer and it is surprising that the literature records no systematic and comprehensive investigation along these lines. Practically all the scattered work on noble metal contacts has centered around platinum as a Standard and has had two more or less distinct aims. One of these has been the replacement of platinum by cheaper materials, and the other, the development of materials of superior electrical performance. The merit of a contact metal has been assumed to be dependent on its infusibility, and since the more precious metals have the higher melting points there has naturally been an association of the two qualities in the sense that the more precious were

Jan 1, 1928

By A. O. Dufresne

Introductory At the Annual Meeting of the Institute, held two years ago, I had the privilege of presenting a paper on Recent Mineral Discoveries in Western Quebec. In it were pointed out the areas favourable for prospecting in that section of Quebec adjoining the mining camps of northern Ontario; the discoveries that ?had been made were recorded; and some of the developments up to that date were reviewed. Since then, two full years have elapsed, during which a considerable amount of serious work has been performed with such results that western Quebec has today six properties about ready to mine commercial ores of gold, copper, and zinc. These results have been brought about after large sums of money had been invested to bring the district to a producing stage. A smelter has been built, and is already producing copper; two railways have extended their lines into Rouyn; and the Provincial Government has shown faith in the future of the district and has spent large sums of money in the building of highways and for other public works. The purpose of the present paper is to review the developments of the last two years, and the work that has been performed in various spheres of activity in that section on western Quebec covering the county of Abitibi and the northern part of the county of Temiscamingue.

Jan 1, 1928

By Chase E. Sutton

The porosity of a sand is usually the measure of its capacity for holding fluid, although porosity is sometimes selective; that is, a small percentage of the actual pore space (voids), particularly in fine-grained sandstones, may be isolated by the cementing material which prevents the entrance of fluids under normal conditions. Obviously, however, porosity determinations are essential to an engineering study of underground conditions of an oil field, and a simple and reliable method of obtaining a reasonably accurate figure for average porosity is desirable. This report describes a method suggested by Ruasell,3 which was used by the writer in the preparation of a report on the Texhoma-Gose pool, Archer County, Tex.4 The conditions in this pool were particularly favorable for obtaining an average porosity figure, in that some 30 to 35 core samples of the pay sand were available for analysis.

Jan 1, 1928

By F. A. McLean

The past decade has witnessed a rapid increase in the number and variety of uses found for internal combustion engines in mining operations. Gasoline engines are now widely used for operating core drills, pumps, compressors, small hoists, switching locomotives, tractors, boats, and other equipment. The heavy-oil engine is employed for operating compressors, generators, shovels, ore-milling machinery, and- in the iron, copper, and coal districts- in connection with that' latest newcomer in modern railroading, the oil-electric locomotive. Each of these applications could well form a subject for a lengthy treatise in itself. This paper, however, will be confined to a discussion of some of the features of internal combustion engines as applied to mine compressing plants and mill drive. Perhaps at no time in the history of mining in Canada has the search for new mines been more vigorously carried on, more old properties rejuvenated, or more remote districts exploited than during the past three years. The mine operator of today has a far wider range of equipment and facilities at his disposal than had the pioneers of Rossland, Cobalt, or Porcupine. Each year now witnesses the hinterland driven farther and farther back as improved forms of transportation, machinery, and methods make possible the exploration of properties once considered too inaccessible to warrant serious attention. Howey, Sherritt-Gordon, Callinan-Flin Flon, Jackson-Manion, Picard Gold Mines, and a number of properties in British Columbia, afford excellent examples of work carried out on an extensive scale miles from a railway, or in comparatively inaccessible mountain regions.

Jan 1, 1928