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By C. Dinis da Gama

In mining, all unit operations are closely interrelated, and the results of blasting are probably the key factor within that sequence. The drilling program prior to blasting is just as dependent upon the desired rock fragmentation as are the loading, hauling, and mechanical crushing operations which are economically and technically influenced by the results of blasting, namely, the size and scatter of the product. What is known today as optimum blasting is the process of designing a blast in order to obtain a certain degree of fragmentation so that overall mining costs are minimized. Applying this criterion often results in a different program than when an individual blasting pattern is chosen only on the basis of the lowest operational cost for that pattern, disregarding what comes before or after the blast. [Fig. 1] shows the characteristic variation of mining unit costs with the degree of fragmentation, or the maximum size of blocks obtained from blasting. From the figure, it can be seen that optimum breakage must correspond to the lowest total costs, but reducing drilling-blasting costs only does not achieve such an optimum solution. Methods of designing surface or underground blasting operations should comply with the optimization criterion, but this compliance is feasible only if a detailed mining system analysis is available. Therefore, predictions of costs of loading, transporting, and mechanical breakage of ore as a function of its size will define a narrow range of variation for drilling and blasting parameters in order to get the minimum total costs.

Jan 1, 1972

By A. R. Rosenfield, G. T. Hahn

The effects of adding 0.025 volume fraction of uniformly dispersed Tho2, particles (particle size -380A) to iron have been examined. The two-phase alloy is shown to have a lower transition temperature and higher cleavage stress than either the base metal or a solid-solution alloy (Fe-3Si). Enhanced cleavage resistance is thought to be a consequence of particles limiting the effective slip distance of dislocations and thus the ability of Pile-ups to act as stress concentrations. Further calculations predict that the highest cleavage strengths are attained with uniform dispersions, where the particle size is kept small (-250A) and the volume fraction is relatively large (-2 to 3 pct). ALTHOUGH a fine dispersion of second-phase particles is known to impart strength to an alloy, the possibility that it might also impart ductility has only recently been explored. Outstanding progress has been made in the production of ductile tungsten alloys containing Tho21,2or (Hf, Zr)C,= but the contribution of the dispersion to ductility has neither been optimized nor fully analyzed. The basis for such an analysis has now been developed1,5 and is discussed briefly below. Experiments on iron are also described that attempt to isolate one of the possible ductilizing mechanisms and test its effectiveness. In analyzing these experiments, it is important to remember that cleavage obeys a stress criterion, and that either a lower ductile-to-brittle transition temperature or a higher cleavage stress is evidence of enhanced resistance to cleavage. DUCTILIZING MECHANISMS Slip Blockage. Cleavage fracture of polycrystals may be initiated at the intersection of a slip band (or twin) and a neighboring grain or a large (-1 to 5 µ) particle. The slip band generates a stress concentration at its head, and either the grain boundary fractures, the particle fractures, or cleavage is initiated in a neighboring grain. Experimental evidence for this viewpoint is found in metallographic studies8-8 and from the observation that cleavage is usually preceded by yielding.8-11 The potency of a slip band as a stress concentrator

Jan 1, 1968

By M. A. Hunter

THIS paper gives the results of an investigation of the specific resistance and temperature coefficient of the electrical resistance of nickel and its important alloy, monel metal. For most of the pure metals, the temperature coefficient of resistance is approximately 0.0004 per degree centigrade at 2.0° C. Nickel and iron, however, are exceptions. This property is important as it gives us good material for the construction of thermometers and other instruments involving electrical control. A summary of information on this subject has been published by the Bureau of Standards.1 The present experiments antedate this publication by several years and as the information obtained is not contained in it, the results of the experiments are published as additional information. ELECTRICAL PROPERTIES OF PURE NICKEL It is generally conceded that the lowest values for electrical resistance are obtained in the purest metal. In the case of nickel, the best material obtainable is electrolytic nickel, which contains approximately. 99.80 per cent. nickel, 0.15 per cent. iron, and 0.05 per cent. copper. Any cobalt that may be present is included in the nickel figure. If the electrolytic sheet has been deposited without intermission, it is possible to cut a section from the sheet and roll it into wire without melting. By this means a nickel wire may be obtained that is uncontaminated by any of the impurities always taken up by nickel during melting.

Jan 5, 1922

By D. D. Dunkin

SANDSTONE has been prepared for glassmaking purposes, and marketed from the White River Valley in-Arkansas at Guion, Izard County, since about 1910-soon after the completion of the White River Branch of the Missouri Pacific R. R. Co. Until 1921, operations were somewhat spasmodic and ended in many failures. In that year a plant was built by the Silica Products Co., Inc., and since that time the operation has been continuous and steady. The land is held under leases, covering about 30 sq. mi. of the best sandstone adjacent to the railroad. Most of the product is shipped to glassmakers. GEOLOGY The St. Peter sandstone is rather widely distributed in north central Arkansas and- is exposed most prominently in outcrops along the slopes of the White River Valley and its tributaries that form the division between the Boston Mountains to the south and the Salem Plateau of the Ozarks to the north. It is of Ordovician age and is generally underlain by Cotter dolomite and capped by Plattin limestone, except in the vicinity of Bellefonte and Everton. At those places, it is a massive cross-bedded, laminated, saccharoidal sandstone; underlying it is the Everton limestone and overlying it, the Joachim magnesium limestone. The sandstone at Everton contains numerous phosphatic pebbles and inclusions of sandy limestone. The irregularity of cross-section, the evidence of sorting action and the phosphatic pebbles appear to be indications of secondary deposition.

Jan 1, 1928

By Wm. Reuben Webster

BRASS is an alloy of copper and zinc. The brasses (using this term to denote all useful proportions of the two constituents) are the most valuable and widely employed of all [ ] nonferrous alloys, because of their high resistance to ordinary corrosive agencies and the very wide range of properties that may be imparted to them by variations in the proportions of the constituents and by variations in mechanical treatment and heat-treatment. Fig. I shows the normal physical properties, as determined by standard tensile tests, of the series when in the annealed condition. Fig. 2 shows the effect of varying amounts of cold-working on an almost pure brass containing 70 per cent copper and 30 per cent zinc. Fig. 3 shows the effect of annealing at various temperatures on the same alloy. This effect is somewhat modi- [ ] fied by the degree of cold-working to which a brass has been subjected, as shown by Fig. 4. A fourth test, which is empirical, has been found useful because of its simplicity the hot hammer test. Samples 1/2 in. in diameter and 3/4 in. long are placed in a suitable furnace. These are withdrawn one at a time at successively higher temperatures and are subjected to the blow of a drop hammer weighing 50 lb. with a drop of 4 ft. The percentages of reduction in length of the cylinders are plotted against temperatures and give a comparative measure of plasticity at different temperatures. The results of this test on several

Jan 1, 1942

By Edwin Ludlow

T HE OPEN FORUM on this subject called by Mr. Hoover at the recent meeting of the Institute' brought out a large number of very able papers, and a very full discussion of all the problems involved. The criticisms of the bituminous industry were: 1. That it was over-developed with the possible output nearly 50 per cent. in excess of the present requirements; that during the summer there were plenty of cars and no orders, and during the winter there were plenty of orders but no cars. 2. That the mines were not properly developed from an engineering standpoint, and that the recovery of the coal varies from 50 per cent. to 95 per cent. 3. That this industry, employing over 600,000 men, could, if running full time, release 100,000 men for other work. 4. That the studies made by the engineers of the Fuel Administration showed that the cost of production increased with a loss of time and that with a 50 per cent. operation the increase in cost was about 40 per cent.

Jan 1, 1920

By Orville R. Lyons

This paper presents a method whereby the amount of misplaced material and the difficulty of the separation can be used to compare coal cleaning equipment of all types, from effectiveness and capacity standpoints. The correlations presented do not include all types of equipment currently available, but the method can be used to evaluate any make or type of coal cleaning equipment, both old and new. THE relative performance of coal washing equipment, or the effectiveness with which any type or make of equipment removes impurities from coal, has been most difficult to evaluate in the past. The most widely used yardstick is the Frazer and Yancey efficiency formula developed in 1922,' but Yancey in a later article states that "washers treating coals of different density composition or operating at different densities of separation cannot be compared directly on the basis of this criterion."' Prior to and since 1922, a variety of other methods has been used for comparison purposes, including the distribution curve, the error area, and the "ecart probable" or probable error. Yancey and Geer in discussing these methods conclude, "Performance can be evaluated in a number of different ways, with the choice of the proper method to use being dictated by the objectives of the investigation and the data available."' It is true that performance can be evaluated in a variety of ways, but if the equipment is to be evaluated on an effectiveness basis, there should be only one universal comparison method. Varying methods have been used because one universal comparison method has not been found or developed. In the article previously quoted, Yancey and Geer state in clear terms the primary concept for a universal comparison method: "One of the simplest, and certainly one of the most obvious evaluations of washery performance is the quantity of sink material in the washed coal and the float material in the refuse. If the washery products are tested at the density at which the washing unit is operated, the sink in the washed coal and the float in the refuse represent material that has been misplaced." The quantity of misplaced material was used as a criterion of washery performance by Lincoln in 1913," by the United States Bureau of Mines in 1938,' by Hancock in 1947," and by the national French research agency Cerchar in recent years.' In 1950 Andersone proposed the use of this criterion as an efficiency value to replace the Frazer and Yancey formula. However, none of the above-mentioned investigators used the misplaced material concept in a manner that would provide universal coal-cleaning equipment comparisons. The Correlation Theory The ideal coal cleaning process would treat all sizes and would make a perfect separation at any given specific gravity. All material lower in density than the desired value would report in the coal product and all material higher in density would report in the refuse product. Unfortunately, no known cleaning process achieves this goal and there seems little likelihood that any process yet to be invented will do more than approach it. When coal is treated in volume under operating conditions, it is impossible to avoid mechanical entrapment, fluctuations in throughput and effective gravity of separation, and the creation of turbulent currents, even when a true heavy-liquid bath is used and the feed is closely sized and contains little intermediate gravity material. This being so, it is possible to appreciate the difficulties inherent in trying to obtain a perfect separation when treating a wide range of sizes and a feed containing high percentages of intermediate material, using turbulent currents to help create the effective separation gravity, under operating conditions which normally tend to be on the overload side. When coal is separated from refuse in any coal cleaning equipment, some refuse always reports to the coal and some coal to the refuse; the writer therefore assumed that there should be a relationship between the total amount of misplaced material produced by any given piece of equipment and the difficulty of separation as represented by the percentage of near gravity material in the feed. With small amounts of near gravity or k0.1 material in the feed there should be less misplacement of material than would occur with large amounts of near

Jan 1, 1953

By Orville R. Lyons

This paper presents a method whereby the amount of misplaced material and the difficulty of the separation can be used to compare coal cleaning equipment of all types, from effectiveness and capacity standpoints. The correlations presented do not include all types of equipment currently available, but the method can be used to evaluate any make or type of coal cleaning equipment, both old and new. THE relative performance of coal washing equipment, or the effectiveness with which any type or make of equipment removes impurities from coal, has been most difficult to evaluate in the past. The most widely used yardstick is the Frazer and Yancey efficiency formula developed in 1922,' but Yancey in a later article states that "washers treating coals of different density composition or operating at different densities of separation cannot be compared directly on the basis of this criterion."' Prior to and since 1922, a variety of other methods has been used for comparison purposes, including the distribution curve, the error area, and the "ecart probable" or probable error. Yancey and Geer in discussing these methods conclude, "Performance can be evaluated in a number of different ways, with the choice of the proper method to use being dictated by the objectives of the investigation and the data available."' It is true that performance can be evaluated in a variety of ways, but if the equipment is to be evaluated on an effectiveness basis, there should be only one universal comparison method. Varying methods have been used because one universal comparison method has not been found or developed. In the article previously quoted, Yancey and Geer state in clear terms the primary concept for a universal comparison method: "One of the simplest, and certainly one of the most obvious evaluations of washery performance is the quantity of sink material in the washed coal and the float material in the refuse. If the washery products are tested at the density at which the washing unit is operated, the sink in the washed coal and the float in the refuse represent material that has been misplaced." The quantity of misplaced material was used as a criterion of washery performance by Lincoln in 1913," by the United States Bureau of Mines in 1938,' by Hancock in 1947," and by the national French research agency Cerchar in recent years.' In 1950 Andersone proposed the use of this criterion as an efficiency value to replace the Frazer and Yancey formula. However, none of the above-mentioned investigators used the misplaced material concept in a manner that would provide universal coal-cleaning equipment comparisons. The Correlation Theory The ideal coal cleaning process would treat all sizes and would make a perfect separation at any given specific gravity. All material lower in density than the desired value would report in the coal product and all material higher in density would report in the refuse product. Unfortunately, no known cleaning process achieves this goal and there seems little likelihood that any process yet to be invented will do more than approach it. When coal is treated in volume under operating conditions, it is impossible to avoid mechanical entrapment, fluctuations in throughput and effective gravity of separation, and the creation of turbulent currents, even when a true heavy-liquid bath is used and the feed is closely sized and contains little intermediate gravity material. This being so, it is possible to appreciate the difficulties inherent in trying to obtain a perfect separation when treating a wide range of sizes and a feed containing high percentages of intermediate material, using turbulent currents to help create the effective separation gravity, under operating conditions which normally tend to be on the overload side. When coal is separated from refuse in any coal cleaning equipment, some refuse always reports to the coal and some coal to the refuse; the writer therefore assumed that there should be a relationship between the total amount of misplaced material produced by any given piece of equipment and the difficulty of separation as represented by the percentage of near gravity material in the feed. With small amounts of near gravity or k0.1 material in the feed there should be less misplacement of material than would occur with large amounts of near

Jan 1, 1953

By T. Sterry Hunt

THERE are about sixty bodies which chemists call elements ; the simplest forms of matter which they have been able to extract from the rocky crust of our earth, its waters, and its atmosphere. These substances are distributed in very unequal quantities, and in very different manners. As regards the frequency of these elements in nature, neglecting for the present those which constitute air and water, and confining ourselves to the solid matters of the earth's crust, there are a few which are exceedingly abundant, making up nine-tenths, if not ninety-five hundredths, of the rocks so far as known to us. The elements of which silica, alumina, lime, magnesia, potash, and soda are oxides, are very common, and occur almost everywhere. There are others which are much rarer, being found in comparatively small quantities. Many of these rarer elements are, however, of great importance in the economy of nature. Such are the common metals and other substances used in the arts, which occur in nature in quantities relatively very minute, but which have been collected by various agencies, and thus made available for the wants of man. It is chiefly of the well-known metals, iron, copper, silver, and gold, that I propose to speak to-night ; but there are two other elements not classed among the metals, which I shall notice for the reason that their history is extremely important, and will, moreover, enable , us to comprehend more clearly some points in that of the metals themselves. I speak of phosphorus and iodine. You all know the essential part which the former of these, com-

By C. C. Hatch, C. R. Larsen, A. L. Mular

INTRODUCTION As part of a general project to simulate a concentrator, the Brenda Mines Limited secondary crushing plant, located near Peachland, B. C., was sampled during the summer/winter of 1975 and during the summer of 1978 to develop a digital crushing plant simulator specific to the Brenda operation. The purpose of this simulator was to study the influence of manipulable process variables on important responses, to permit study of alternative circuit configurations if desired and to perform off-line optimization. This chapter describes the methodology employed to develop the simulator (1,2) along with typical applications thereof. SECONDARY CRUSHING PLANT FLOWSHEET Figure 1 is a schematic diagram of the Brenda Mines Ltd. secondary crushing plant circuit. The 41,000 tonne coarse ore stockpile(a) is -17.8 cm oversize (3B belt) from two 2.4 m x 6.1 m double deck vibrating screens (not shown). The screens are fed by 2 conveyor belts operated in series with two 198 cm apron feeders that handle discharge from a 152 cm x 226 cm primary gyratory crusher(520 KW). The primary crusher (not shown) treats up to 2725 tonne/hr of run of mine ore. Minus 1.9 cm undersize from the primary screens (#19 belt), referred to as the primary fines, joins secondary screen undersize (#18 belt) for conveyance to fine ore bins (not shown). Feed from the coarse ore stockpile is transferred by means of vibrating feeders and two 120 cm conveyors (#6 and #7) to transfer belts #8 and #9 (Figure 1). The belts feed two secondary 2.1 m standard heavy duty cone crushers (bl and b2). Each crusher is equipped with a modified coarse mantle liner and a standard coarse bowl liner. Mantle throw is 9.2 cm; nominal close side set is 3.2 cm. Crusher .countershafts (443 rpm) are driven by single 260 KW synchronous motors (710 rpm). Discharge from the secondary cone crushers joins discharge from four 2.1 m tertiary heavy duty shorthead cone crushers (fl, f2, f3 and f4). With the exception of the cavity (modified medium mantle liner and standard coarse bowl liner; close side set is nominal .84 cm) and motor (224 KW), these machines are similar to the secondary crushers. The combined discharge is transferred from a 183 cm conveyor to #14 belt which empties into a 1452 tonne secondary screen surge bin (c). Vibrating feeders beneath the bins feed five 2.4 m x 6.1 m double deck vibrating screens (dl, d2, d3, d4 and d5) sloped at 200 from the horizontal. The upper decks are punched plates with 2.7 cm x 7.6 cm slots. Lower decks are woven wire (1.27 cm diameter) sections with

Jan 1, 1982

By AIME AIME

THE Employment Bureau of the F. A: E. S., conducted under- the direct supervision of the secretaries of the four Founder Societies, has wanted to extend its activities and usefulness but it is operating right up to the limit of its budget; consequently, anything which requires the expenditure of more funds cannot be -undertaken, for the present. A great deal of time has been spent in recording, classifying, and interviewing the men listed, but owing to the business depression, only a comparatively small number of men have been placed' luring the last few months. There are men in New York from all over the country. What the Bureau needs is more positions available. With this in view, a number of high-grade engineers, themselves in need of employment, volunteered their services for a publicity campaign in the City of New York. A definite mode of procedure was evolved, and the success of the movement has been considerable, so much so that it has been thought well to call it to the attention, of members elsewhere, so that similar committees ' and campaigns might be organized in other cities. Following is a chronological arrangement of the methods used.

Jan 1, 1921

By Ezequiel Ordoñez

THE great activity with which the oil resources of the northern Cantons of the State of Veracruz have been developed has largely resulted from the great success obtained by the important explorations carried out since 1902 in the Ebano district in the North, and several years later near Tuxpam, in the South. It must not be thought that these successes were quickly obtained, since the preliminary studies by good experts, the acquisition of what were thought to be the most promising coast lands, the extensive clearing thereof, and finally the number of unsuccessful drillings at great depth, signified an original outlay of some ten's of millions of dollars before finding commercial oil. The discovery of oil in industrial quantities at Cerro de la Pez, Ebano district, and the famous Dos Bocas gusher some years later, which was burned, once and for all made famous the Veracruz coast, where today is concentrated the Mexican output of mineral oil. In .1917, this production was nearly 50,000,000 bbl. It is well known that this output represents only a fraction of what the wells in actual production can furnish, because with adequate means of transportation and storage, the present extraction could be somewhat over 300,000,000 bbl. a year. These enormous potential oil resources of the Veracruz coast proceed from a relatively small number of wells, scattered over a few oil fields, separated from each other by large unexplored areas, wherein may be found other favorable fields which, in time, will undoubtedly become just as great centers of oil production. Experts who know our Gulf Coast believe that lands with commercial oil resources lie not only between the Panuco amid Tuxpan Rivers, but that indications are that the oil zone of Mexico, with more or less interruption, takes in the coast zone from Northern Tamaulipas to the foot of the Sierra Madre of Chiapas, and the banks of the Usumacinta River. This generalization is not merely the outcome of optimism, but is the result of the persistency with which one finds, throughout this Gulf Coast, the most usual characteristics upon which we depend for recognizing oil-bearing lands.

Jan 5, 1918

By Henry Phelps Howland

During the last decade no topic has created more interest or received more thought among blast-furnace men than coke. One reason for this is, undoubtedly, the remarkable increase in the use of byproduct coke. Formerly our coke was made at a distance from the furnaces and by a distinct organization. There was little cooperation or development possible under these conditions. Today the situation is greatly changed. Much of our coke is made by the organization operating the furnaces and the coke oven is operated with the primary object of obtaining the best results in the blast furnace. The effect of changing the method of coke manufacture, even in some minor detail, is often felt almost immediately at the blast furnace. There naturally results one of the most valuable assets of the byproduct coke oven, i.e., the possibility of increased blast-furnace efficiency due to close observance and correct operation of the ovens. The results are evident, but often it is difficult correctly to account for them. In attacking the solution of a problem of as much importance as why one coke is better than another, there are facts which should be kept clearly in mind. The author hopes, in this paper, to bring out some points relative to the use of carbon in the blast furnace which will be of value in solving this question. GeÜner's Ideal Working Years ago GrÜner made a statement regarding the use of carbon in the blast furnace, which has been very generally accepted by metallurgical and blast-furnace men. I quote this theory as given by Prof. Richards on p. 248 of Metallurgical Calculations: "From the standpoint of the generation of the maximum quantity of heat in the furnace, GrÜner was right in formulating his dietum of the ideal working of a blast furnace, vie.: All the carbon burnt in the furnaee should be first oxidized at the tuyères to CO and all reduction of oxides above the tuyères should be caused by CO, which thus beeomes Co2."

Jan 1, 1917

By Albert Sauveur

As director of the Division of Metallurgy of the Technical Section of the Air Service, American Expeditionary Forces, from August, 1917, to January, 1919, I devoted much time to the study of the steels best suited to the construction of aircraft. It became apparent at a very early stage of my investigation that the practice of builders varied greatly in regard to the number of different steels to be used, to the kinds of steels, and to their treatment. Some manufacturers employed as many as fifteen steels while the builder of one of the newest motors, favorably passed upon in the United States, assured me that two or, at the most, three kinds of steel was all he needed to produce satisfactory results. In the matter of treatment, the manufacturers were also greatly at variance.. Some treated their steel with considerable refinement, while others paid but scant attention to this feature. Some manufacturers case-hardened many parts, while others used the case-hardening process sparingly, if at all. Nickel-chromium steels were used at some works for case-hardening while at other plants this treatment was applied exclusively to carbon steels. Air-hardening nickel-chromium steel was used extensively by some and not at all by others. Considerable variance existed likewise in regard to the steels used for admission and exhaust valves. The conclusion was obvious, that no two manufacturers of airplane motors held like opinions as to the steels to be used or as to the treatment they should receive. Was it to be inferred from this that the many committees and associations that had been created, in part at least, for the standardization of aircraft steels had failed to make proper recommendations or that the manufacturers had ignored their recommendations? Confining our inquiry to the committees and associations that had dealt with this question in England, France, and the United States, it was found that in Great Britain the British Engineering Standards Committee, now the British Engineering Standards Association, had devoted much time to the problem of satisfactory standards for aircraft steels. In April, 1918, this Association presented a set of specifications

Jan 9, 1919

By H. M. Chance

Recent research work has shown that coal can be produced, at reasonable cost, from almost all coal-mining districts containing not more than 3 to 8 per cent. of ash. From coal so produced, an abundant supply of coke, suitable for blast-furnace operation, can be made containing from 12 down to 6 per cent. or less of ash. These statements apply broadly to the Appalachian coal belt, including most of the mining districts in Pennsylvania, Ohio, West Virginia, Kentucky, Tennessee, and Alabama. The exceptions will generally be found among those coals carrying a prohibitive percentage of sulfur. Any gravimetric heavy fluid method of separation will effect a reduction in the percentage of sulfur, but this reduction may not be sufficient to produce, from coal unfit for metallurgic use, a product that can be so used. When a large part of the sulfur is in the form known as "organic sulfur, "or is present as very finely disseminated and homogeneously distributed pyrite, possibly it cannot be eliminated from the low-ash coal produced. When the sulfur exists as pyrite in distinct layers, bands, or nodules, or when it is finely disseminated but is irregularly distributed, often a low-ash coal low enough in sulfur to make good metallurgic coke can be produced from relatively impure coals. It has generally been assumed that the quality of coke on which blast furnaces must be operated depends on the geographic location of the furnace, and that the grade of coke on which a blast furnace must operate is that produced from the best coal obtainable by careful mining; or if the coal is prepared by washing, hand picking, or other means by which the foreign impurities are removed, that the grade of coke on which the furnace must operate depends on what has been termed the "inherent ash" of the particular coal. The term "inherent ash " is generally understood to mean the percentage of ash present after all removable (free) impurities, slate, fireclay, high-ash bony coal, and pyrite have been removed, and is usually applied to the percentage of ash present in run-of-mine coal from any mine after these impurities have been removed. Perfect washing, or perfect preparation, is understood to be attained when the percentage of ash in the washed coal is reduced to the percentage of inherent ash; that is, of ash that cannot be removed by the washing processes in common use. Wash-

Jan 1, 1924

By Joseph A. Holmes, Henry Kreisinger

At the Mining Experiment Station of the U. S. Geological Survey, in Pittsburg, an investigation of the process of combustion is being carried on in a specially-designed furnace having an unusually long combustion-chamber. This work is conducted by a con~mittee consisti~lg of 11. Kreisinger, mechanical engineer; Dr. J. C. W. Frazer, chemist; and Dr..J. K. Clement, physicist. The problem, essentially one of physical chemistry, is estremely interesting to all who are concerned in the burning of coal or the construction of furnaces. The main object of these experiments is to ascertain the relation between the amount of' the volatile combustible driven from the coal and the combustion-spaces necessary to burn it completely. Our best steam-coals vary from 15 to 45 per cent. in volatile matter and from 40 to 75 per cent. of fixed combtistible. The greater part of the latter is burned on the grate: but the volatile combustible leaves the freshly-charsed coal and must be burned in the combustion-space. If this space is not large enough, the volatile combustible mill leave the furnace only partly burnecl, and the result will be a considerable heat-loss and a smoky stack. Strictly speaking, the factor which determines the completeness of combustion of the volatile matter, after it has been mixed with a certain amount of air, is the length of time the mixture is allowed to remain in the combustion-space; but this length of time depends on the extent of the space itself. Let us suppose, for instance, that, when a given coal is burned at a certain standard rate, the volume of the volatile combustible driven oft' per second is 10 cu. ft. Adding, say, 10 cu. ft. of air, the volume of the resulting burning mixture is increased to 20 cu. ft. If the combustion-space is 30 cu. ft., the burning mixture will stay in it,

Jan 1, 1911

By J. Eric Belford

The Kidd Creek orebody is a massive base metal sulphide deposit with surface dimensions of 168 m by 670 m. The steeply dipping ore- body has been evaluated to a depth of 1 524 m. To date, the mining of the orebody has been divided into three stages. The first stage of mining was an open pit operation which supplied ore from 1966 until 1977 when a depth of 219 m was reached at the widest or north end of the orebody. The second stage of mining, called No.1 Mine, was the development of an underground mine to replace the pit and recover the ore from the floor of the pit to a depth of 792 m. Development of the underground mine started in 1969. Full production of 273 000 tonnes per month was attained in 1977. The third stage of mining called No.2 Mine, was initiated to accommodate a production expansion and included the development of a second underground mining operation to recover the ore from the bottom of No.1 Mine, i.e. the 2600 level; to a depth as yet undetermined but most likely the 4600 foot level. Development of the No.2 Mine began in 1974. Full production of 91 000 tonnes per month will be achieved in 1982. The choice of the 2800 level as the partition between the two underground mines was based on the following factors: The 2600 level is the lowest level which can conveniently be mined through the No.1 Mine crusher on the 2800 level. Development and trial stoping methods for mining at depth could be evaluated in the 2600 to 2800 block utilizing the existing hoisting facilities of No.1 Mine. Early development of the ore in the 2600 to 2800 block would provide additional mill feed sooner than could be achieved by developing from No.2 Shaft. The underground mining plan then is to mine from the pit floor down to the 2600 foot level and at the same time mine from the 2800 level down to at least the 4600 foot level. PLANNING The Kidd Creek operations are designed to follow a logical mining sequence. The grade of ore supplied to the concentrator is the result of following the mining plan. The philosophy of mining has been to mine downward in horizontal slices. In the case of No.1 Mine the slices are 122 m thick while in No.2 Mine the slices will be 183 m thick. The point of this approach is to mine the pillars immediately after creating them rather than allowing them to stand, deteriorate and generate uncontrollable situations. Two types of ore are handled separately to optimize recoverable values in concentrates. The 'A' type ore is a copper zinc ore with some silver and little lead. The 'C' type ore is a zinc silver ore with some lead and copper

Jan 1, 1981

By Ezequiel Ordonez

The great activity with which the oil resources of the northern Cantons of the State of Veracruz have been developed has largely resulted from the great success obtained by the important explorations carried out since 1902 in the Ebano district in the North, and several years later near Tuxpam, in the South. It must not be thought that these successes were quickly obtained, since the preliminary studies by good experts, the acquisition of what were thought to be the most promising coast lands, the extensive clearing thereof, and finally the number of unsuccessful drillings at great depth, signified an original outlay of some tens of millions of dollars before finding commercial oil. The discovery of oil in industrial quantities at Cerro de la Pez, Ebano district, and the famous Dos Bocas gusher some years later, which was burned, once and for all made famous the Veracruz coast, where today is concentrated the Mexican output of mineral oil. In 1917, this production was nearly 61,000,000 bbl. It is well known that this output represents only a fraction of what the wells in actual production can furnish, because with adequate means of transportation and storage, the present extraction could be somewhat over 300,000,000 bbl. a year. These enormous potential oil resources of the Veracruz coast proceed from a relatively small number of wells, scattered over a few oil fields, separated from each other by large unexplored areas, wherein may be found other favorable fields which, in time, will undoubtedly become just as great centers of oil production. Experts who know our Gulf Coast believe that lands with commercial oil resources lie not only between the Pgnuco and Tuxpan Rivers, but that indications are that the oil zone of Mexico, with more or less interruption, takes in the coast zone from Northern Tamaulipas to the foot of the Sierra Madre of Chiapas, and the banks of the Usumacinta River. This generalization is not merely the outcome of optimism, but is the result of the persistency with which one finds, throughout this Gulf Coast, the most usual characteristics upon which we depend for recognizing oil-bearing lands.

Jan 1, 1920

By B. O. Pickard

With more than a score of shafts and numerous stope openings to the surface, all inter-connected underground; with underground temperatures high, often exceeding 100' wet bulb; with an ore presenting a dust health-hazard; with certain rocks giving off inert gases; with an altitude of 6000 ft. above the sea level and a dry desert climate, the Tonopah mines offered an interesting problem to the student of metal-line ventilation. Tonopah is not an old mining district, relatively speaking. It was discovered in 1900 and Tonopah soon was a boom camp. Ry 1910 the mines of this district had paid many millions of dollars in dividends. At the time of the 1921 ventilation study, mining had passed its peak of production and the operators were striving to reduce costs, to discover new orebodies, and to attract desirable workmen. In 1925, the camp was operating on a still less prosperous basis, but the several managements had not relaxed in their efforts to keep the mines on a paying basis, neither had they lost their faith in the ability of the mines and the price of the silver to "come back." Early in the fall of 1921 the Bureau of Mines was invited by the mine operators at Tonopah, Nev., to make a detailed study of the underground air conditions in the Tonopah silver district. D. Harrington, chief engineer of the Safety Service Division of the Bureau, who was then directly supervising the ventilation studies, detailed district engineer B. 0. Pickard, mining engineer E. D. Gardner, surgeon C. E. Kindall, and petrographer IT. Insley to carry on the study. G. S. Rice, as chief mining engineer of the Bureau of Mines, was in general charge of the work. Upon the completion of the study each operator was furnished a report on conditions in his mine. In 1925, a supplemental study at Tonopah was made by the district engineer at the request of several of the operators, and each operator advised on the changes in his respective air conditions and recommendations for improvements. Recently, several of the operators gave the

Jan 1, 1927

By George Rice

THE subject of dust explosions in coal mines first appears in the Transactions of this Institute following the first great mine disaster that happened in bituminous mines of the United States. This was the Pocahontas explosion, which occurred Mar. 13, 1884, causing the loss of 112 men. The operating company wisely asked the technical assistance of the Institute, requesting that a committee be appointed to investigate and report. This committee consisted of Messrs. Bramwell, Buck, and Williams, who, after careful study, reached the conclusion that the explosion was due "either to dust alone or to dust quickened by an admixture of fire-clamp too slight for detection by ordinary means." This is perhaps the first time in this country that coal dust was considered to be the chief agency in a mine explosion.. The report is given in the Transactions, vol. xiii, p. 237 (1885). It is particularly worthy of note that the committee called attention to "the necessity of full-sized tests and systematic experiments. " In the same volume of the Transactions, there is a most interesting paper reviewing the literature relating to coal dust, by E. S. Hutchinson, entitled Notes on Coal-Dust in Colliery Explosions. Mr. Hutchinson gives a historical account of observations on the part played by coal dust in mine explosions, beginning with Messrs. Lyell and Faraday's report on the Haswell colliery explosion in 1844, in which it is said "much coal gas had been made from this dust in the very air itself in the mine by the flame of the firedamp, which raised and swept it along, and much of the carbon of the dust remained unburned only from want of air." The subject lay dormant until 1875 when William Galloway began some coal-dust experiments in a small gallery at a mine in South Wales of which he was manager. At that time he considered the presence of firedamp necessary for continued propagation of a dust explosion; but in 1884, the year of the Pocahontas disaster, he stated that no earlier author-than himself had credited coal dust with being a principal factor in mine explosions, relegating firedamp to a secondary place.

Jan 10, 1914