Search Documents

By R. W. Raymond

[NoTE.—-This paper was presented at the Pittsburgh meeting in a partially completed form, and I fully expected to obtain, before the period of its publication, both the data and the leisure required for its completion. The hygiene of collieries was to have been separately considered, and the sanitary conditions of various metallurgical industries connected with mining were to receive an extended discussion, while at the same time the points treated in the paper as prosented at Pittsburgh were to have more ample illustration from American and European sources. Delay in obtaining expected information, and the continuous pressure of professional work, have prevented hitherto the execution of this plan ; and I can now publish only a portion of what I had designed to contribute to the subject. In the meantime this portion, but slightly changed, has been included as a chapter on the Hygiene of Metal Mines in a work entitled Hygiene and Public Health,, edited by Dr. A. H. Buck, of New York. An excellent chapter on the Hygiene of Coal Mines, contributed to the same work by Mr. Henry C. Sheafer, of Pottsville, affords me an opportunity to supply one of the deficiencies above alluded to. Mr. Shearer's chapter contains much material in the way of explanations not required by professional readers; And be moreover devotes a considerable space to the explosive gases, falls of roof, and other causes of accidents to life or limb—a branch of the subject not belonging strictly to bygiene. I therefore make extracts only from his treatise.—R. W. R ] It is convenient to divide mines, with reference to this subject, into two classes, collieries and metal-mines. Subterranean quarries, rock-salt mines, etc., present no conditions requiring them to be separated from the latter class.

Jan 1, 1880

(SECRETARY'S NOTE.) The following discussion of the papers of Van Hise, Emmons, Lindgren and Weed, read at the Washington meeting, February, 1900, and printed on pp. 282 to 498 of this volume, comprises communications to the Secretary, received at various times before the Richmond meeting, February, 1901, and, for the most part, presented at that meeting. These communications are introduced at this point in the present volume, in order that they may precede the papers of Vogt, hemp, Lindgren, Rickard, etc., presented at Richmond, and therefore not forming part of the material considered in them. Since many of the contributors have mentioned in one communication several of the papers referred to, no attempt is here made to divide their remarks and distribute the fragments under separate headings. In each contribution, however, the several topics are indicated by subtitles. R. BECK,* Freiberg, Saxony : Prof. Veal Hise's Paper.-The paper of Prof. Van use (p. 282) represents a great step of scientific progress, in that the circulation of underground waters has never before been presented with such clearness, ill the light of modern chemical and physical knowledge. The theories of the formation of ore-deposits which follow the author's general survey of the currents and solvent power of atmospheric waters in the earth's crust do not, indeed, seem to be novel, being essentially an amplification of Le Conte's views; but the proofs adduced in their support are in many particulars so original that no one can read without profit this portion of the paper. Entirely new (though largely in agreement with the papers of Emmons and Weed, presented at the same meeting of the Institute) are the sections dealing with the formation of the rich sulphides of the precious metals, and especially the regeneration of normal sulphides, such as galena, etc., in vein-zones immediately beneath the ground-water level. Nevertheless, it appears to me that Prof. Van Hise, in the course of his most instructive exposition of unquestionable, yet still locally limited, phenomena, has been too much biased in favor of the " descensionists." This is indicated by the small importance which he attaches to the intimate genetic relation between epigenetic deposits and the plutonic hearths of the earth's interior.

Jan 1, 1902

By Thomas C. Atchison

An understanding of the physical processes involved in breaking rock with explosives will lead to better blasting techniques. In this chapter known rock breakage principles will be outlined, some conjectural ideas will be discussed, and areas needing further study will be pointed out. The principles outlined will serve as a basis for the design of blasting rounds described in the following chapter. 7.2-1. Factors Important to Rock Fragmentation. The efficacy of explosives as tools for rock fragmentation lies in their ability to deliver almost instantaneously large amounts of energy to a limited portion of the rock. When an explosive charge is detonated in a drill hole, its energy is released in a very small fraction of a second in the form of gas at extremely high pressure and temperature. The mechanics of the transfer of this energy to the rock and the resulting breakage are complex and not completely understood. Factors that have been identified as important to the fragmentation process may be grouped in three categories: explosive parameters, charge loading parameters, and rock parameters. EXPLOSIVE PARAMETERS. Explosive parameters known to influence breakage are density, detonation velocity, detonation impedance, detonation pressure, gas volume, and available energy. Detonation pressure is probably the best indicator of an explosive's ability to break solid hard rock. Detonation pressure is roughly proportional to the product of density and the square of the detonation velocity. The relative ability of different explosives to transmit their pressure to stress in a given rock is function of their detonation impedances. Detonation impedance is the product of density and detonation velocity. The volume of gas released in the explosive detonation undoubtedly is of importance, at least in the later stages of breakage, and is probably

Jan 1, 1968

By Sidney A. Swensrud

MUCH discussion has occurred as to the use or uses which might be made after the war of either or both .of the large diameter (24 inch and 20 inch) War Emergency pipe lines built by y the United States Government during the war, to move crude petroleum and refined products such as gasoline and light distillate fuels. Indeed, the disposition and future use of these lines constitutes, in the minds of many people, one of the most important problems of postwar readjustment in the Oil Industry. The two lines, running from points in Texas to the New York-New Jersey-Philadelphia area, were constructed only because of the inability during the war to continue normal ocean tanker movements from the Gulf Coast to the East Coast. Physically they could continue after the war to move crude or refined products, and it appears that lines of such large diameter as these, if operated at or near capacity, could move these liquids at costs per barrel which might be considered in the same general cost range as for tanker movements.1 If, therefore, we were to look forward at the end of the war to a shortage of tankers, it is probable that the continued use of these pipe lines for petroleum movements to the East Coast would be worth considering, as against building new tankers to take over the movement, provided there were no other economic or national defense reasons for restoring tanker fleets and no other better use for the pipe lines. Because of the extensive tanker construction program which has been and still is in progress, and because of our Navy's marked success in combating the submarine problem, it appears to be quite possible, however, that instead of a shortage of tankers at the end of the war, we may have a surplus instead. If this should turn out to be the case, then there would seem to be considerable doubt that these lines would continue to be used for moving petroleum or products to the East Coast at the expense of tying up tankers. It would hardly seem probable that the owner of any such tankers would ship via one of the large lines at the expense of tying up one of its own tankers, unless the pipe line tariff rate charged was lower than the out-of-pocket cost of operating a tanker as against the out-of-pocket cost of keeping it tied up. And considering that a substantial part of the cost of operating a tanker goes on even when it is tied up, it is very difficult to figure out how any pipeline tariff could be established that would be low enough to compete with individually owned tankers that otherwise would be idle. Certainly a pipe line tariff rate high enough to cover direct costs plus even a low rate of depreciation and return on the investment would be far above the out-of-pocket tanker operating costs. In view of these considerations, it has seemed desirable to examine with some care some of the various alternatives that have been suggested as to other possible uses to which these lines might be put. One of these is for transportation of natural gas to the New York-New Jersey Philadelphia area. This Eastern area, located at the destination of these lines, contains the heaviest concentration of population in the United States, and is not now served with natural gas. At the other end of the lines lie the greatest discovered natural gas reserves in the United States, if not in the world, and many

Jan 1, 1944

By Irwin Roman

IT has been known for many years that when a wire is moved in a magnetic field, an electromotive force is developed which is proportional to the rate at which the wire is moved in a direction perpendicular to the magnetic intensity and to the magnetic intensity itself. If the ends of the wire are connected to a current indicator, the current behaves exactly as though the source of electromotive force were a galvanic cell. If a wire is wound circularly and rotated uniformly around a diameter not parallel to the intensity, the current flowing through the wire will be alternating of sinusoidal shape. If, instead of a single loop, there are several turns wound in a short helix, the electromotive force developed will be approximately proportional to the number of turns, the area of the helix and to the speed of rotation. The maxi-mum electromotive force will be devel-oped when the axis of rotation is perpen- dicular to the field; if this is not so, only the component of the intensity that is perpendicular to the axis of rotation is effective. This is the principle of the usual earth inductor. With a few turns of wire and comparatively slow rotation, FIG. 1.-MAGNETIC GRADIOMETER. it is possible to produce a considerable deflection of a galvanometer. If two similar coils are rotated together at two different points for which the magnetic field intensities perpendicular to the axes of rotation are different, the electromotive forces developed will each depend on its corresponding intensity and be a measure of that intensity. If the inten-sities are sufficiently different so that the electromotive forces may be compared, the two intensities may be compared. This is the principle

Jan 1, 1934

By William Johnson

IT is now recognized that several important types of reactions in metallic systems proceed by the formation of nuclei and the growth of these nuclei. The process of freezing is a simple example of this, as Tammann pointed out years ago.1 Tammann held that ' the rate, of freezing is determined by a rate of nucleation, expressed as the number of nuclei formed per unit volume of unfrozen liquid per second, and a rate of growth of these nuclei, expressed as the linear rate of radial growth in units of length per second. For isothermal freezing the conception is simple; for ordinary freezing, extending over a range of temperature, it is not as simple, for the values of the two constants must change with change in temperature. There is ample evidence that the postulated mechanism is correct even though a quantitative derivation of the rate of isothermal or of ordinary freezing in terms of the two constants has been lacking. In recent years other reactions have been found to proceed in a similar fashion. It has been well established, particularly by Bain,2-8 that. the formation of pearlite from the eutectoid decomposition of the solid solu-tion austenite proceeds in such a way, and Polanyi and Schmid, Tammann and Crone, Karnop and Sachs, and others9-11 have shown that the process of recrystallization proceeds in a similar way. Isothermal reaction rates have been determined for eutectoid decom-position by a number of investigators. Bain's2-8 work on the formation of pearlite from austenite is especially valuable in this respect-the type of isothermal reaction curve obtained, as illustrated in Fig. 13, showed an initial slow rate, accelerating to an intermediate maximum rate which then decelerated to the completion of the reaction; similar curves have been obtained by Wever and his collaborators.12 Other eutectoid decompositions show similar behavior: for example, the decomposition of the beta eutectoid in the copper-aluminum system, studied by Smith

Jan 1, 1939

By John Norton

IN recent years, the damping capacity of metals has come to be recognized as an important index of certain types of structural change. In a number of instances, this property has proved to be particularly sensitive, but insufficient work has been done to permit a general inter-pretation. There is considerable question at the present time as to just what factors are responsible for the internal dissipation of energy when a metal is carried through a cycle of stress, and these factors must be ascertained if the value of the damping method as a metallurgical tool is to be determined. Since internal stresses are among the chief causes of dissipation of internal energy, or damping capacity, it was thought that a study of the changes in damping during the recovery and recrystalliza-tion of a cold-worked metal might throw some light upon the subject, particularly if the damping changes were correlated with other properties that are better understood. Probably more work has been done on the recrystallization phenomena of alpha brass than on any other metal, so this was chosen as the material for the present investigation. Damping measurements on brass have been made by Förster and Köster.1 They showed that the annealing of a brass that had been cold-drawn to 50 per cent reduction produced a rapid fall in the damping, a flat minimum occurring at approximately the temperature of recrystal-lization. The damping remained at a low value until grain growth was well under way and then it increased rapidly with increasing grain size. Köster and Rosenthal2 continued the work in greater detail. They pointed out that the damping decrease does not correspond to the hard-ness drop but occurs at a lower temperature, suggesting that the relief or redistribution of internal stresses has a large effect while the actual recrystallization effect is small. They also show the increase in damping at the higher annealing temperatures. Their curves are reproduced in Fig. 1.

Jan 1, 1940

By R. J. Watson

In an earlier paper, Ehrenburg and Watson1 published the develop ment for a potential function by which it is possible to obtain the electric potential at points on the surface of the ground when a current I passes between two electrodes and the subsoil is composed of parallel, homogeneous layers. In view of the continued interest in the resistivity method of electrical prospecting, the author has considered it desirable to publish the results of a number of theoretical studies making use of this potential function, and also the results of a considerable number of tests with models designed to show the soundness of the mathematical theory. It is hoped that these results will prove how erroneous the various empirical rules for depth determination may be. It has always seemed puzzling to the author that one can find, in papers published comparatively recently, statements upholding empirical rules for depth determination, and attributing most of the irregularities of resistivity curves to vertical discontinuities in resistivity in the subsoil. It would indeed be fortunate for the geophysical investigator if such a simple rule held. However, numerous investigators have proved both theoretically and by the success of their field work that such a rule does not hold, even by a "rough approximation" in many cases. On the other hand, as is shown in the development to follow, if the underground conditions are favorable it is possible for such empirical rules to give a satisfactory depth determination. Authors should be more careful about making such sweeping statements about the accuracy of these empirical rules because the relative simplicity of the field work places the method in the hands of any interested experimenter, and he is likely to become completely disgusted with the method after he has made several obviously wrong interpretations by empirical rules. There are simple and rapid methods for finding out whether the ground beneath the electrodes is sufficiently similar to the conditions

Jan 1, 1934

By Walter C. Lawson

The primary objective in laying track in panel sections is to reduce the number of track laborers required. This is possible because the work is mechanized. Moreover, because the work is mechanized and each of the operations needs only a few men, and each is self-contained, the work can be carried on at night as well as in daylight; therefore, the method provides a means of preparing tracks on more than one shift. The laying of tracks in open pits and quarries in panel sections is not new but new methods have been made possible by the introduction of new types of equipment. The purpose of this paper is to describe the methods that are followed in the Morenci open pit. General Mining Operations Full-scale ore production at Morenci is about 50,000 tons daily. The normal yearly output of ore and waste is 32,000,000 tons, of which 30,000,000 tons is handled by rail haulage. This requires the building of approximately 47 miles of loading and other temporary tracks during a 12 months' period (Fig I). Broken ore and waste is loaded into 90-ton capacity dump cars with 5-cu-yd full-revolving electric shovels. Shovel banks are uniformly 50 ft high. They are blasted with churn drill holes and the broken material from a blast is loaded out with two shovel cuts, the first one being called (locally) the "splatter" cut and the second one the "clean-up" or "face-up" cut. When a shovel is making its clean-up cut, the loading track is about 70 ft from the toe of the bank and, under normal conditions, a bank is blasted against it without removing the track. It is thus evident that each track is used for two shovel cuts before relocation is necessary, inasmuch as a single position serves for both the clean-up cut prior to blasting and for the splatter cut following the blast. The normal advance of a solid bench by a single blast is 40 ft (Fig 2). Preparation OF Panel Grade In preparation of panel grades bulldozers and rooters are used for the bulk of the work and an auto-patrol road grader for the final stage. At Morenci, bulldozers have always been used for track-grade preparation, but before the introduction of the other two types of equipment grades were uneven and irregular at best, and always necessitated a big gang of track laborers to hand-block under the ties with rocks after a track was laid into place. High blocking also made poor track because of instability and caused frequent derailments. Under these conditions derailments were generally bad as re-railing became difficult. Much track was torn up and many tics broken in the process. The inadequacy of the hand-blocked track, together with the inefficiency of hand blocking, constantly pointed, to the desirability of reducing the amount of labor required, so various means were tried to improve conditions, such as wood

Jan 1, 1949

By C. M. Loeb, T. E. Norman

THE use of ball, rod and tube mills for grinding ore, cement and other materials has grown so rapidly during the past forty years that the world's annual consumption of ferrous grinding media for these mills is now estimated to be between one half million and one million tons per year. Ferrous grinding balls constitute the major portion of this tonnage. Obviously they represent sufficient value to justify thorough studies' of the factor sgoverning their performance. The selection of grinding balls is governed principally by: I. Quality (wear resistance, impact resistance, soundness, and the like). 2. Sources of supply and delivered cost. 3. Grinding characteristics or efficiency in the ball mill. This paper deals principally with the quality of ferrous grinding balls. In the study of these factors certain data relative to the fundamental nature of ball wear in ball mills have been obtained. These data are also presented and discussed briefly. THE DEVELOPMENT OF A SUITABLE WEAR TEST A study of the fundamental factors governing the quality of grinding balls has been hampered seriously by the fact that a competent test has, in the past, involved the purchase of several hundred tons of balls of a specific type which were then run in one or more ball mills for a period ranging from several months to several years' duration. Often, during the period of test, it became necessary to change operating conditions or the character of the ore fed, to the test mill with the result that the rate of ball consumption changed and the test figures became of little value. Under such circumstances, progress in the development of better grinding balls, has been necessarily slow. Economic factors and variations in the quality of balls produced by different sources of supply generally make it necessary for each mill operator to determine for himself the most suitable type of balls for his mills. In our own ball mill grinding operations at Climax, Colo., we were faced with this problem. After we had run a few large scale wear tests at considerable expense we decided to investigate the possibilities of a small scale wear test which would be capable of testing numerous types of balls within a relatively short time. The most important requirement of any test is, of course, that it give results which can be used to predict accurately the wear in full scale operations. It was known that Ellis and his associates1,2 had developed a method of testing grinding balls by small scale tests run at the Ontario Research Foundation. Ellis' method of testing was used as a starting point in our investigations. In the course of our tests a number of modifications of the original method were found to be desirable so that, by an evolutionary procedure, a method of small scale

Jan 1, 1947

By Hugh S. Spence

In the winter of 1941-42, muscovite mica was discovered by a young prospector, Justin Purdy, in the township of Mat-tawan, Nipissing District, Ontario, a few miles north of the small settlement of Eau Claire, which lies on the main Transcontinental Highway (No. 17) between Mattawa and North Bay. Muscovite had been known for many years to occur in the general Mattawa region, and various small efforts at production had previously been made by individuals working scattered deposits in the area. These minor activities, however, had never led to production of any consequence or the discovery of any important mica bodies. The Purdy finds were made in a heavily timbered, mountainous area lying about three miles north of the low-lying settled land along the highway, and in a section not hitherto prospected. The mica taken by Purdy and two partners from surface outcrops proved so remarkable in point of size of trimmed sheets that the find attracted considerable attention, and the area surrounding the three claims taken up by the prospectors was quickly blanket-staked by various interests. Though a number of other mica-bearing pegmatite dikes were found later on these stakings, none proved as rich as those on the original Purdy ground; very little commercial mica was obtained from them and attempts to develop them were short-lived. Purdy and his partners sold their initial production to dealers in Ottawa and Hull, where the Canadian mica industry long has centered. Young Purdy, unfortunately was killed in a motor accident in the early summer of 1942. His father continued mining operations for a few months and produced and sold a considerable amount of mica. In October 1942 the Purdy holdings were acquired by lnspiration Mining and Development Co. of Amos, Quebec, which had been active in staking in the area. This company formed a subsidiary, Purdy Mica Mines, Limited, to develop the property. Under the energetic management of Joseph R. Norrie, rapid progress was made, and production soon attained important proportions. Realizing from the outset the unusual character and potential value in the war effort of the Purdy discovery, the Metals Controller, Department of Munitions and Supply, at once arranged with the Department of Mines and Resources for an official geological report on the area, and also drew the attention of the War Production Board in Washington to what seemed likely to prove a highly important source of strategic-quality mica. Officials of WPB were sent up in the Summer of 1942 to inspect the property, and so impressed were they with the possibility that it might become of high

Jan 1, 1948

By Hugh S. Spence

In the winter of 1941-42, muscovite mica was discovered by a young prospector, Justin Purdy, in the township of Mat-tawan, Nipissing District, Ontario, a few miles north of the small settlement of Eau Claire, which lies on the main Transcontinental Highway (No. 17) between Mattawa and North Bay. Muscovite had been known for many years to occur in the general Mattawa region, and various small efforts at production had previously been made by individuals working scattered deposits in the area. These minor activities, however, had never led to production of any consequence or the discovery of any important mica bodies. The Purdy finds were made in a heavily timbered, mountainous area lying about three miles north of the low-lying settled land along the highway, and in a section not hitherto prospected. The mica taken by Purdy and two partners from surface outcrops proved so remarkable in point of size of trimmed sheets that the find attracted considerable attention, and the area surrounding the three claims taken up by the prospectors was quickly blanket-staked by various interests. Though a number of other mica-bearing pegmatite dikes were found later on these stakings, none proved as rich as those on the original Purdy ground; very little commercial mica was obtained from them and attempts to develop them were short-lived. Purdy and his partners sold their initial production to dealers in Ottawa and Hull, where the Canadian mica industry long has centered. Young Purdy, unfortunately was killed in a motor accident in the early summer of 1942. His father continued mining operations for a few months and produced and sold a considerable amount of mica. In October 1942 the Purdy holdings were acquired by lnspiration Mining and Development Co. of Amos, Quebec, which had been active in staking in the area. This company formed a subsidiary, Purdy Mica Mines, Limited, to develop the property. Under the energetic management of Joseph R. Norrie, rapid progress was made, and production soon attained important proportions. Realizing from the outset the unusual character and potential value in the war effort of the Purdy discovery, the Metals Controller, Department of Munitions and Supply, at once arranged with the Department of Mines and Resources for an official geological report on the area, and also drew the attention of the War Production Board in Washington to what seemed likely to prove a highly important source of strategic-quality mica. Officials of WPB were sent up in the Summer of 1942 to inspect the property, and so impressed were they with the possibility that it might become of high

Jan 1, 1948

By Thomas L. Garwood, F. C. Menk

IT is generally accepted that no method of coal cleaning except froth flotation is effective in cleaning dust. In the majority of coals mined in the United States the dust sues contain a high percentage of impurities, hence the removal of the dust from the coarse sizes lowers the impurity content of these sizes. Dedusted coal is desired as a means of providing a better feed to cleaning plants because of increased efficiency in I both dry and wet plants. In dry-cleaning plants, a dedusted feed makes for a pervious and uniform bed. With a dusty feed the fines tend to segregate in the feed stream and pass en masse over the air separators, causing a lack of uniform aeration and fluidity of the bed necessary to efficient cleaning. In wet-cleaning plants dedusting of the feed often decreases the sludge problem to the point of eliminating the necessity of wasting wash water. It may be advantageous to eliminate sludge-settling equipment in favor of dedusting equipment, to provide the advantages of a dedusted feed to the wet-washing process. Dedusting advantages may include: (1) the removal of fusain, especially advantageous in plants washing coal intended for metallurgical coke; (2) prevention of the gradual build-up of solids in the wash water, with a consequent variation in the washing ability of the system; (3) prevention of the loss of dust to the sludge ponds, providing instead a fuel for local consumption or special markets. DEDUSTING The practice of dedusting, sometimes called aspirating, has presented a problem in disposing of the dust and intermediate small sizes recovered in the process. It has been found that no difficulty is experienced in disposing of the intermediate sizes, since they are free of fine dust and burn freely on grates built for small coal. They handle well, flowing freely from bins and hoppers and into conveyors, and pulverize easily. They have a low angle of repose. In tests made on this size as a feed to coke ovens, the results have been excellent, in that the natural breakdown of coal in handling and shooting in the mine gives this small-size coal good coking characteristics-producing a strong, fingery coke structure. Deduster dust from Illinois coal has been

Jan 1, 1950

As 1970 develops and industrial minerals stand at a crucial point in their progress, research and development programs appear to be the key needed to open up new uses for each mineral's future growth. Radically new processes are needed for making a host of new synthetic products from mineral raw materials which will more nearly meet the demanding specifications required for high performance in space, nuclear and defense applications. Consumer applications for high temperature environments will be needed and are important for continuing the nations economic mineral position. In addition, an acute materials problem limits the effectiveness of some of the newer concepts for controlling ail pollution. What is needed then, according to a report printed by the National Academy of Sciences, is the carefully planned development of a limited number of major centers at universities to provide for both basic research and training of personnel; the nurturing of interdisciplinary mechanisms for research and problem solving within these centers; the achieving of a better balance between physics and chemistry within research, emphasizing the chemical aspects of the material sciences; and the enhancement of a broader professional identity by unifying the various disciplines involved into a possible federation of existing societies which have an interest in the problems. [EE] presents its 1969 annual industrial minerals review, where individual authors evaluate the status of each industrial mineral and recount the major developments which occurred during the year.

Jan 1, 1970

By D. W. Brunton

The maps of our large mines are usually prepared with the greatest care; and it is somewhat singular that, in compari~on with the great amount of time and money spent in surveying and platting, 80 little actual use is made of them. Almost the only purpose for which a completed survey-map is afterwards consulted, is the determination of the relative position of the different workings to each other, and to the boundary-lines of the property. After the completion of such a map, it should be made the beginning of another, and in most cases a far more important undertaking, namely, its utilization as a starting-point for a complete inventory of the company's underground possessions. The ordinary mine-survey map, being nothing but a record of what has been done, is, in one sense, only ancient history. To increase its value, such additions should be made as will render it a complete statement of the amount and value of ore in sight at any particular time, and a guide for future development. Comparatively little extra labor is involved in this undertaking, since the larger and most expensive part of the work has already been completed when the mine has been surveyed and mapped. The necessary additions consist in working out and platting on the maps, the geology of the mine as exposed in the workings, in such a manner that the geological survey may be of daily use in the development and operation of the mine. The first step towards the production of a geological map consists in tracing individual level-sheets from the general or composite map. The area to be included, outside of the property in question, will depend very much on local conditions; but, for geological, legal and commercial reasons, it should be extended as far as reasonably practicable. The scale to be

Jan 1, 1906

By Oswald J. Heinrich

The deposit of rock salt along the shores of Lake Huron, in Canada, has been brought before the public during the last six months, in consequence of the developments made by the diamond drill at Goderich. It is likely to be of more than common interest in the future, since now actual operations have been commenced to exploit the deposit and work it by regular mining. The methods of mining rock salt being but little known in this country, it may be of interest to make a few general remarks in regard to them before entering, upon the description of this new mining enterprise. According to the conditions under which salt is .found in nature, various methods have been resorted to, in course of time, to make it available for the human race. They consist in: A. Natural or solar evaporation. B. Artificial evaporation, either exclusively or in connection with the former. C. Mining the rock salt in its natural state, and converting it to a marketable product, if need be, by simply pulverizing it. Without going into the details of the various methods of making salt available in an economical point of view, dependent on its degree of pority, or on various local influences, we cannot refrain from alluding to the general principles which influence the mining and manufacturing of salt in countries where they have been carried on for hundreds of years. ECONOMICAL CONDITIONS FOR SUCCESS. Salt being one of the articles of prime necessity, and one universally distributed throughout nature, it must always be sold at a comparatively low price. It would even be quoted in the market at prices far below those now ruling, if it were not for the high duties generally imposed upon it, for purposes of state revenues. But looking closer into the subject, it will be found that this duty is probably one of the least oppressive, although in some countries it exceeds sixfold the cost of profitable production. To produce the article at the lowest possible cost requires, therefore, a

Jan 1, 1879

By George Gardner

THE application of wet cleaning processes for the beneficiation of bituminous coal has created in some localities a problem in the recovery and disposal of fine solids in the washery water. The maximum allowable concentration of these solids in the washery circuit that is consistent with satisfactory operation of the cleaning units remains a controversial point. It has, however, been generally recognized for a number of years that some degree of control should be exerted over the concentration of such material. Early methods of control involved intermittent or continuous dis-charge of a portion of the plant slurry into near-by streams or settling ponds, and this persisted even after the adoption of settling tanks or cones. The practice is not always economical, for two reasons: first, because of the waste of coal, and, second, because it is sometimes difficult and expensive to obtain an adequate supply of water. The latter condi-tion often is aggravated by chemical treatment of the make-up water that is necessary to prevent excessive corrosion of plant equipment. The modern approach to this problem has been the adoption of continuous thickening devices. However, because such equipment occupies consid-erable plant space and is somewhat expensive to construct, the practice of loading these thickeners beyond their rated capacity is widespread, there-fore often the performance of such units is not altogether satisfactory. In recent years, European washeries have increased the rate of settling of the fine coal from the slurry by the addition of specially pre-pared starch solutions. These reagents cause flocculation of the solid particles and thereby increase the rate of sedimentation.

Jan 1, 1939

LOCAL SECTIONS (There are 60 Local Sections in the United States, 4 Foreign ) ADIRONDACK Established June 18, 1952 Paul W Allen, Chairman William Webb, Vice-Chairman Edwin Briggs, Secretary-Treasurer National Lead Company Mac Intyre Development Tahawus, New York Paul W Allen, Section Delegate R G Fleck, Alternate Section Delegate

Jan 1, 1954

By J. L. Jernegan

In a former paper laid before the Institute, entitled Lead and Silver Smelting in Chicago, I endeavored to give a description of the manner in which argentiferous lead ores from the far West were treated in that city, and also described the method employed in the desilverization of the silver-lead produced from the ores. It will perhaps be remembered, that very siliceous ores, principally from the Emma mine, Utah, containing over 40 per cent. of silicic acid, were then being treated at the works of the Chicago Silver Smelting and Refining Company in the reverberatory furnace, with the use of metallic iron, in the form of borings, as a precipitating medium for the lead ; and that the extraction of the silver from the resulting bullion was effected by the Balbach process. The Swansea Works, also the works at Brighton, just outside of this city, and those of S. P. Lunt, were at that time treating ore of a similar character by the same method. The inadequacy of the process for the ores then under treatment was, in a manner, pointed out by me in the paper above referred to. Since the time of its writing, many and important improvements have been made in the metallurgical treatment of western ores in Chicago. Most ores are now roasted previous to reduction, and the latter operation is conducted in the shaftfurnace instead of the reverberatory. Such is the fact at least at the Swansea Works, the largest in the city, and here it was where the first steps were taken in this direction. In selecting these works as the subject of this paper, I am in hopes that the description given of the varions metallurgical operations, as they are there now conducted, will serve to give an idea of the improvements introduced

By G. B. Walker, S. A. Falconer, S. J. Swainson, H. H. Vogel

During the past few years much interest and attention has been focused on a relatively new method of ore concentration, which utilizes the principles of sink and float and employs as the heavy medium a suspension in water of a finely ground solid, such as galena or ferrosilicon. Although a relatively recent development, much progress has already been made in applying heavy-media separation processes to a considerable number of ores. Eight plants in this country and abroad are now treating approximately 10 million tons of ore annually by heavy-media separation (sink-float) processes, including lead-zinc, lead, iron, garnet, tin and tungsten. At the annual meeting of the A.I.M.E. in 1941, three interesting papers (unpublished) dealing with heavy-media separation (sink-float) processes of ore concentration as practiced in four commercial units in the United States were presented by Victor Rakowsky, Grover Holt, Elmer Isern and Robert Ammon. These papers gave an excellent exposition of the principles of sink and float, as well as the operating practice in two iron-ore-beneficiation plants, the Harrison and the Merritt, of Butler Brothers, in Minnesota; the Central mill of the Eagle Picher Mining and Smelting Co.; and the Mascot mill, of the American Zinc, Lead and Smelting Co. Augmented by pictorial descriptions and a working model demonstrating the processes, these papers evoked a great deal of interest and discussion. In fact, in reporting the high lights of the meeting in the April 1941 issue of Mining and Metallurgy, Professor Taggart made the statement that " preconcentration by heavy suspension was Miss A.1.M.E 1941 so far as milling is concerned." Although to date the greatest application of heavy-media separation from the tonnage point of view has been for the treatment of lead, zinc and iron ores, these processes have a much wider field of usefulness. In this regard, it is to be noted that recently new heavy-media separation plants for treating cassiterite ore and garnet ore have been placed in successful operation. Moreover, numerous other types of ores have been found to respond well to these processes when tested on a semi-commercial scale, and it is expected that in the near future a considerable number of new plants will be erected. In view of the fact that heavy-media separation processes offer such attractive possibilities, particularly now, when the mining industry is being called on for an even larger production than ever before has been attempted, despite shortages of labor and supplies, it was felt that a description of some of the successful separations that have been worked out during the past year in the Ore Dressing Laboratory of the American Cyanamid Co. on a variety of ores of strategic importance would be of interest. The purpose of this paper, therefore, is to present the essential data relating to investigations of heavy-

Jan 1, 1943