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By Samuel G. Lasky

The writer has been interested in determining the mineralogic dis-t,ribut.ion of silver in the base-metal ore of thc Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.' This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many districts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the proportionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impracticable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathematical method used, and to point out the value of using this method even when assays of pure specimens are available. Value of the Mathematical Method The obvious way of attacking the problem would be to separate cleanly large quantities of ore into its component minerals and then to determine the average silver content of each mineral by assay of representative samples. Since an absolutely clean separation is not feasible, it has been the practice, as mentioned above, to assay pure specimens of the different minerals. No one will contend seriously that the silver content of a base-metal mineral is constant throughout any particular deposit, and it will

Jan 1, 1935

By Samuel G. Lasky

The writer has been interested in determining the mineralogic dis-t,ribut.ion of silver in the base-metal ore of thc Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.' This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many districts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the proportionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impracticable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathematical method used, and to point out the value of using this method even when assays of pure specimens are available. Value of the Mathematical Method The obvious way of attacking the problem would be to separate cleanly large quantities of ore into its component minerals and then to determine the average silver content of each mineral by assay of representative samples. Since an absolutely clean separation is not feasible, it has been the practice, as mentioned above, to assay pure specimens of the different minerals. No one will contend seriously that the silver content of a base-metal mineral is constant throughout any particular deposit, and it will

Jan 1, 1935

The writer has been interested in determining the mineralogic dis-t,ribut.ion of silver in the base-metal ore of thc Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.' This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many districts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the proportionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impracticable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathematical method used, and to point out the value of using this method even when assays of pure specimens are available. Value of the Mathematical Method The obvious way of attacking the problem would be to separate cleanly large quantities of ore into its component minerals and then to determine the average silver content of each mineral by assay of representative samples. Since an absolutely clean separation is not feasible, it has been the practice, as mentioned above, to assay pure specimens of the different minerals. No one will contend seriously that the silver content of a base-metal mineral is constant throughout any particular deposit, and it will

Jan 1, 1935

By Samuel G. Lasky

The writer has been interested in determining the mineralogic dis-t,ribut.ion of silver in the base-metal ore of thc Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.' This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many districts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the proportionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impracticable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathematical method used, and to point out the value of using this method even when assays of pure specimens are available. Value of the Mathematical Method The obvious way of attacking the problem would be to separate cleanly large quantities of ore into its component minerals and then to determine the average silver content of each mineral by assay of representative samples. Since an absolutely clean separation is not feasible, it has been the practice, as mentioned above, to assay pure specimens of the different minerals. No one will contend seriously that the silver content of a base-metal mineral is constant throughout any particular deposit, and it will

Jan 1, 1935

By E. C. Truesdale, R. K. Waring

THE Research Division of The New Jersey Zinc Company (of Pa.) has conducted, over a period of years, numerous tests of the reducibility of various zinc ores and the reactivity of various kinds of coal, using a number of different experimental methods. Most of these tests have involved the reduction of mixtures of ore and coal. In such cases the following simultaneous reactions are believed to be mainly responsible for the production of zinc, as was shown by Bodenstein1 some years ago: ZnO + CO = Zn + CO2[I] C + CO2 = 2CO[2]. Each of these reactions is dependent upon the other for the supply of CO and C02, respectively, and the over-all rate of formation of zinc vapor will be determined by the slower of these two reactions. An analogous pair of reactions sometimes of importance is: ZnO + H2 = Zn + H2O[3] C+ H2O=CO+H2[4] While it is possible to obtain an indication of the relative reducibility of various ores, or of a fine versus a coarse ore, by testing them with a given coal, and while coal reactivities may be measured in a corresponding manner, a more direct determination of relative reaction rates is possible by carrying out the desired reactions, such as I and 2, separately and under reproducible conditions. It is one purpose of this paper to present some of the results that have been obtained by the latter method. C. G. Maier2 discusses the relative rates of reactions I and 2 and concludes that while at relatively low temperatures reaction I is faster than reaction 2, this difference becomes less with increasing temperatures, although at smelting temperatures reaction I is still the faster. He also says (p. 48), "At temperatures . . . between 1100° and 1300°C the zinc oxide reduction reaction is intrinsically more rapid than its physical limitations; that is, it is limited by gas diffusion rates." In the course of numerous reactivity tests involving the separate use of reactions and I and 2, we have obtained data that show by direct experiment, we believe for the first time, the correctness of Maier's statements concerning these reactions. We also include data on the relative rate of reaction 3, involving reduction by hydrogen. Finally, some interesting results obtained by carrying out the reduction of a zinc ore-coal briquet in streaming atmospheres of nitrogen, carbon monoxide and hydrogen, respectively, are presented.*

Jan 1, 1941

By Thos. W. Gibson

The object of taxation is the raising of a revenue. Unless a tax accomplishes this, it is a failure. The right to take for public purposes a part of the moneys obtained from the carrying on of private enterprises is an attribute possessed only by a lawful government, and may indeed be called the supreme attribute of government. In free, democratic communities this power must of necessity rest upon the consent of the governed. Power implies obligation, hence it is obviously the duty of a government, in framing a system of taxation, to provide one which, while effective in producing a revenue, is also just and impartial. • It will be conceded that mines and mining property ought to bear a fair share of the public expenditure. The question is, upon what basis taxation should proceed. Two separate taxing principles are usually contended for: Taxation should be proportionate to the benefits received by the person or property taxed; taxation should be based on ability to pay. A third is sometimes added, taxation should have reference to the extent and value of the natural resources enjoyed. As applied to mining taxation, it is pointed out by those who support the fist mentioned basis that, mines being usually situated in rocky and hence sparsely peopled regions, mining companies are frequently obliged to construct roads, railways, telegraph and telephone lines, schools, water and sewerage systems, and many other amenities and conveniencea of civilization the cost of which in regions better suited for agriculture, and consequently more thickly populated, has either been defrayed locally, or can be spread over a sufficiently large taxable group of people to materially lighten the financial burden on the mine. The mining company, it is argued, having made these outlays, should receive credit for them and be relieved of taxation to a corresponding extent. There may be some force in this contention, but the situation is capable of relief without attempting to place taxation upon so unworkable a basis as the value of benefits received. Who is to be the judge of these benefits, and how are they to be valued? The very existence of a mining company and its ability to carry on business in peace and security depeind on the prevalence of law and order, which is a result of good government. The state provides protection against violence, and courts of law for

Jan 1, 1920

By R. H. Schnitzel

Internal-friction peaks have been observed in tungsten single crystals at about 300° and 400°C. The characteristics of these peaks are similar to interstitial peaks observed in other bee metals; therefore, the origin of these peaks appears to he the Snoek mechanism. The interstitial responsible for the peak at about 300°C has not been identified. Carburizing increases the magnitude of the peak at about 400°C; consequently, it appears reasonable to suppose that the specific interstitial associated with this peak is carbon. The activation energies associated with the 300° and 400°Cpeaks are about 35,000 and 45,000 cal per mole, respectively. INTERNAL - friction peaks resulting from the stress-induced diffusion of interstitials (Snoek relaxation peaks) have been frequently observed in bee metals.1-5 Attempts to detect Snoek relaxation peaks in tungsten have, however, not been fruitful.' Failure to find Snoek peaks in sintered tungsten can perhaps be attributed to one or more of the following difficulties: a) the relatively low purity of the sintered tungsten; b) the lack of extensive metallurgical knowledge about tungsten-interstitial alloys, such as suitable interstitial dosing and quenching procedures; and c) the inconsistency of some of the interstitial analyses of tungsten, which reflects itself in one's inability to be sure of the nature of the specimens. This present investigation did not overcome all of these difficulties for successful tungsten internal-friction measurements. Some of these difficulties still persist and new difficulties were encountered during the course of this investigation. Nevertheless, the use of electron-beam tungsten single crystals having somewhat greater purity levels than sintered tungsten combined with appropriate carburizing and quenching procedures permitted a reasonable attempt to be made. As a consequence, internal-friction peaks were observed in these tungsten single crystals at about 300° and 400°C. These peaks were found to be unstable, since they annealed rapidly away during a sequence of internal-friction measurements. Hence, it was necessary to construct an apparatus having a faster heating rate to study some of the details of these peaks. From the behavior of these peaks as well as our knowledge of similar peaks in other bee metals, one can reasonably conclude that these peaks are caused by residual interstitial impurities within these crystals. Further investigation of these peaks after the application of various metallurgical treatments lent credence to this supposition. EXPERIMENTAL TECHNIQUE The internal friction of tungsten single crystals was measured using two different pieces of apparatus both of which are of essentially the same conventional design, namely the KE type of torsion pendulum. The important difference between these two types of apparatus was in the attainable heating rate and method of protection of the specimen from atmospheric contamination. The apparatus designated "number 1" was enclosed in a vacuum chamber which was heated by an externally mounted furnace. It had a slow rate of heating which was estimated to be about 4°C per min from room temperature to about 350°C and then about 1°C per min to 600°C. The internal friction of tantalum was measured with this apparatus and the established Snoek peaks were found.' These tantalum peaks in the temperature range from room temperature to 400° C served as a check for the apparatus. The apparatus designated "number 2" having a faster heating rate than number 1 was not elaborate. It consisted of a mounted nickel tube to which split heating elements were attached. Argon was used as the protective atmosphere. The measured heating rate was about 12° to 15°C per min whereas the cooling rate was somewhat slower at about 10° C per min because of the increased difficulty encountered in stabilizing the temperature. No surface oxidation of the specimen was noted after any test. This apparatus was also checked with the known peaks of tantalum.1 The preparation of the single-crystal specimens for internal-friction measurements consisted of centerless grinding the crystals from an approximate 0.200 in. diameter to 0.030 to 0.040 in. in diameter, and then electropolishing them to about 0.020 in. in diameter. Single crystals processed in this manner are designated as being in the virgin condition. Since the length of crystal varied from 3 to 9 in., the test frequency varied from about 1 to 2 cps. The frequencies of measurement, axial orientations, and chemical analyses for the various crystals are listed in Table I. The controlled addition of carbon into tungsten is a difficult problem. Attempts to find the critical conditions necessary for an equilibrium treatment were not fruitful. Therefore, a simple nonequi-librium method was used. The addition of carbon to these crystals consisted of appropriately combining three treatments—carburizing to achieve a case, annealing to partially dissolve the carbon into the

Jan 1, 1965

OLIVIA'S recent revolution, by hindsight, seems to have been inevitable. The misery of the majority of the people, coupled with the economic crisis engendered by the refusal of the United States to meet Bolivian demands for a higher tin price, gave the National Revolutionary Movement party all the excuse it needed for overthrowing the government. Most of the mines in Bolivia are owned by three families. Precisely what it will mean to the United States is still a moot question. Argentina, with a mixture of Marxism, Fascism, and few twists created by the Perons, is in a position to grab off much of the tin we need. Because of the contingencies of geographical location, language and a natural simpatico, Argentina may be able to continue its efforts to oust the United States from its South American markets. Point Four aid was supposed to be given to Bolivia, but only for agriculture. Even this was entirely too slow. Mining, Bolivia's other major source of income was forgotten by the Washington planners. Primary aim of the new power will be to diminish its dependence on the world tin market. At a time when the free world is fighting a battle for control of metal, it stands a chance of losing an important source of supply. With the accent placed on agriculture and other industries, mining in Bolivia is certain to suffer. Argentina will be in a position to get the available supply of tin, make a strong ally in the world order of things, and add to its power play against the United States in South America. Ten labor groups have formed the Bolivian Central Workers Union. The first item on their list for immediate action is the nationalization of the mining and railroad industries. They also came out for agrarian revolution and diversification of industry. President Victor Paz Estenssoro has promised to appoint a committee for the investigation of nationalization of the mines. At least, this is indicative of a feeling for the need for caution.

Jan 1, 1952

By H. M. Zoerb

Based on the belief that operating details are a definite contributing factor to major economies, this paper traces the development of crushing cavity design in Symons cone crushers to attain maximum liner utilization. Wear rates are analyzed and compared in this presentation and drawings illustrate succeeding design changes. IN these times of rising labor and material costs, it has become more and more necessary that attention be paid to some operating details which, in their obscurity, may he the key to major economies. Liner wear in crushing cavities of secondary and tertiary crushers can become an appreciable cost item when the material to be crushed is hard and abrasive. This item of cost not only includes the value of the crushing members, but also more intangible costs such as labor and lost production due to more frequent replacement. The variables which are encountered in ores and minerals to be reduced; the design of plant and machine application; the sizes, shape, and fineness, characteristics of the crushed product; the moisture; hardness; friability; and abrasiveness of the material to be crushed are all influencing factors which must be taken into consideration in the selection of a crusher, and particularly in the design of crushing cavity and liners to be used in a crusher. Through a research program undertaken in cooperation with many operators of Symons cone crushers a new approach to crusher cavity design was made, resulting in the development of liners for specific operations which showed: 1—maximum utilization, as high as 70 to 80 pct of original weight of metal, and 2— maximum capacity of unit during the greater portion of its life. It has been found that liners so designed for a given operation will show added economies in power consumption, maintenance, and general wear and tear on the crushing unit. Initial work in the so-called tailoring of crushing cavitles was begun on the tertiary or fine crushing units where as a rule reduction ratios were low, varying from 3 to 6. Parallel or sizing zones in the lower portion of the crushing cavity were too long, resulting in a tendency to pack. It was found that very little additional crushing was done in the parallel zone after the initial impact in that zone and that a relatively small amount of' additional crushing was done by attrition, which required very careful feed control. A small amount of over-feeding would result in packing which not only consumed power but caused unnecessary liner wear as well. The illustrations which follow in this discussion will show only contours of crushing cavities, and for purposes of simplification the cavities will be considered only in their closed position. The first step, therefore. was to reduce the sizing zone to a minimum. This was done by removing the lower portion of the liner as shown in Fig. 1. The result of the change was a saving of 15 to 20 pct in liner cost, less power consumption, with no change in capacity. This change in design, while an improvement, did not go far enough. As wear took place, the change in the liner was not uniform throughout its entire length, resulting in a restriction of the feed opening and thereby loss of capacity. Furthermore, progressive wear of the liner had the effect of lengthening the parallel zone until finally the entire crushing cavity was all parallel zone, see Fig. 2. It is obvious from the reduced feed opening of the worn liner that the ability of the machine to receive material is lessened considerably. Furthermore, the long parallel zone with its worn, irregular profile did not operate at its highest efficiency. The first attempt to overcome this difficulty was carried out on a 5 1/2-ft crusher installed in a plant producing roofing granules. The material being crushed was a very hard graywacke and the crusher was closed-circuited with a screen having .232-in. slotted openings. A radical change in contour was developed, as illustrated in Fig. 3. Equal wear lines on both concave and mantle are designated 1, 2, 3, etc. The method of development of this contour is as follows: Since adjustment for wear is vertical, corresponding intersections of wear lines and vertical lines developed concave and mantle contours which maintained equal but lengthening wear surfaces in the parallel zone. The ideal contour, of course, is one in which the length of the parallel zone remains constant, but because of present foundry practice and heat treating characteristics this is impossible.

Jan 1, 1954

By LEWIS F. THOMAS

MINING geologists and mining engineer, rarely give due thought to the geography of mining deposits. They realize, it is true that what may be ore in one place would be only worthless rock in another because f the in accessibility of a smelter r a market; and they may consider the lack of a supply of labor, or water, or power to carry on operations. But they do not think (of these things in terms of geography. Geography may be defined as the science of relationships between earth and man, so geographers are vitally interested in the how and why of mining as it is carried on at different place, having entirely different environment-. Such environments are geographic complexes or composites of natural and cultural elements, which are listed and briefly discussed in the following paragraphs.

Jan 1, 1941

By Colin C. Rae

The absence of paraffin and other oil hydrocarbons in the soil although they are concentrated in extensive deposits in some localities, the common distribution of plant remains through many formations that are not productive for oil, and many other factors, seem to indicate the existence of an intermediate organic compound between the complex plant compounds and the petroleum hydrocarbons; and much evidence points to the humus acids or associated organic compounds, which are probably collected by surface waters and concentrated in certain areas by means of precipitation by electrolytes, which would be contained in sea water or possibly in various inland seas or lakes. Present-day Evidence There are many present-day evidences of the association of petroleum with humus acids. Binney, in 1912, made observations without explanations on the peat mosses of Down Holland, England, where he found petroleum being formed by decomposition in the presence of an infiltration of sea water. The analysis of a typical peat will show its relationship to the humus acids under consideration. Sample No. 1, SamplE No. 2. PXr Cent. PER CENt. Water......................... 20.0 29.6 Ash.......................... 3.0 3.05 Fiber.......................... 47.0 54.95 Humus acids................ 30.0 12.50 J. D. Haseman and others have noted the association of asphalt and hydrocarbons with the swampy, boggy areas, particularly adjacent to the sea. Many of the rivers carry much humus acid in solution, and some tropical rivers carry in the aggregate millions of tons of humus each year. The amount of humus is a variable factor, depending on climatic conditions, and on the salts and alkalies present in the water, also on the density and temperature.

Jan 1, 1923

By Colin C. Rae

The absence of paraffin and other oil hydrocarbons in the soil although they are concentrated in extensive deposits in some localities, the common distribution of plant remains through many formations that are not productive for oil, and many other factors, seem to indicate the existence of an intermediate organic compound between the complex plant compounds and the petroleum hydrocarbons; and much evidence points to the humus acids or associated organic compounds, which are probably collected by surface waters and concentrated in certain areas by means of precipitation by electrolytes, which would be contained in sea water or possibly in various inland seas or lakes. Present-day Evidence There are many present-day evidences of the association of petroleum with humus acids. Binney, in 1912, made observations without explanations on the peat mosses of Down Holland, England, where he found petroleum being formed by decomposition in the presence of an infiltration of sea water. The analysis of a typical peat will show its relationship to the humus acids under consideration. Sample No. 1, SamplE No. 2. PXr Cent. PER CENt. Water......................... 20.0 29.6 Ash.......................... 3.0 3.05 Fiber.......................... 47.0 54.95 Humus acids................ 30.0 12.50 J. D. Haseman and others have noted the association of asphalt and hydrocarbons with the swampy, boggy areas, particularly adjacent to the sea. Many of the rivers carry much humus acid in solution, and some tropical rivers carry in the aggregate millions of tons of humus each year. The amount of humus is a variable factor, depending on climatic conditions, and on the salts and alkalies present in the water, also on the density and temperature.

Jan 1, 1923

By G. S. Brooks, L. G. Duncan

During the past few years, the Mineral Point Zinc Co. has had under consideration the improvement of various types of gas-filtering apparatus used in the removal of dust from crushing and milling plants, in the manufacture of oxide, and on blast-furnace fume and sintering furnaces. The original equipment of the various plants of the company was, of course, along lines of the standard stationary bag house. These houses required large surfaces, hand shaking, and varied only in the manner of the collection of solids and in the distribution of the gas. , Early in 1908, the first trial of a mechanical bag house was made at Nassau Plant at Depue, Ill. The duty of this installation was on dust-laden gas from a fine-crushing mill. The Printz and Rau bag machine was finally adopted and put into operation. This ingenious machine embodied what were then to us two novel features in bag-house practice: 1. An intermittent crinkling and snapping of the filtering fabric to free the meshes of solids. 2. A reversal of gas flow for a short period by a temporary connection with the suction trunk. This equipment worked fairly well except in cold weather, when we ran into condensation troubles. Had we at that time understood more fully some of the limitations of fabric filtering work, these might well have been remedied. We were impressed by this experience, however, with the efficiency of sudden tension on the fabric under suction. After a study had been made of some of the western blast-furnace houses using the reversal-of-flow feature, experiments were started early in 3 914 with a view to developing an automatic equipment along the best lines of our past experience. The objects sought were: 1. Keeping labor out of the houses for hygienic reasons. 2. Reduction of labor costs. 3. Reduction in size of bag houses. 4. Accessibility. 5. Ability to handle relatively hot gases where required.

Jan 1, 1918

By Ernest O. Kartinen

This report is the accumulation of eight years of experience on only one small phase in the business of oil production. It is not intended as a final report but rather as a progress report dealing with the internal corrosion of oil field dehydrating tanks. The corrosion of dehydrating tanks continues to be a problem in the production of crude oil. The deterioration hy corrosion of these tanks falls into three general classifications: (1) Atmospheric corrosion of exterior areas, (2) corrosion of the underside of deck and the rafters and top area of the upper row of staves in that part of the tank which is known as the vapor space, and (3) corrosion of the bottom and shell areas, and the steam coils which are normally immersed in water and thus exposed to the corrosive action of the water. Atmospheric corrosion is primarily a paint problem, and has been omitted in this discussion. The corrosion in the vapor space, in this company's experience, which has been of great concern only in one area. has also been omitted in this discussion. The third, and most troublesome type of corrosion, and the one with which this report deals, is that which occurs in the water-exposed areas of dehydrating tanks, and, to a lesser degree. in some stock tanks. The operating temperature of these waters varies from 80°F to 160°F and the salt counts run from a few thousand to as high as 25.000 parts per million. Corrosion in these tanks occurs in three forms: (1) pits, (2) ringworm type of attack along the vertical and horizontal bolt seams, and (3) as a general attack, spread over a wide area. Steam Coils In dehydrating tanks, our experience has been that the steam coils are the first to show signs of corrosion, and then the shell and bottom areas. This action is not uniform throughout this company's operations. Some installations have coil troubles with very little tank trouble, and some show just the opposite. But in the majority of cases the coils are the more seriously corroded areas. This may be partly due to the fact that we have tried by periodic application to keep a protective coating on the interior areas of the tanks, and some protection has been afforded by these coatings. Through the years several types of hot and cold coatings have been tried with many various methods of cleaning the steel, ranging from use of cleaning solvents to hot and cold Oakite washes, as well as sandblasting. Although experience has shown that a longer life expectancy of a coating is possible after a very thorough steel cleaning job, it has still been necessary to recoat these tanks at least every two or three years. Until a few years ago, vertical spiral steam coil bundles were installed when the tanks were originally erected. When these coils needed replacement, in some cases within 18 months, it was necessary to remove a couple of shell staves to accomplish this task. This required a down time period of several days and was often very inconvenient to the production operations of the leases. This problem was considered on the basis that the coils were expendable, and thus. to eliminate any unnecessary down time when changing coils, the vertical spiral coils were discarded in favor of horizontal flat coils which could be taken in and out of the tanks by way of the cleanout openings, and put together with unions. This made a fairly easily replaceable and repairable coil. But it was still very much of a nuisance when repairs were necessary. Efforts to increase the useful life of the dehydrating tanks led to the adoption of galvanized tanks at an increased initial cost. The zinc coating was depended upon for protection and no other protective coatings were applied. In July, 1944. during the development of a new lease, a 3-ring 1,500 bbl, black iron water tank was converted into a dehydrating tank with steam coils to handle the new production. This tank was coated inside with a cold, brushed-on coating, for protection against corrosion. After approximately 18 months of service, holes developed in the tank and the steam coils. The tank was emptied and cleaned for repairs. The coils were so badly pitted that it was felt advisable to replace them. Coating Becomes Loose Inspection of the tank showed the protective coating to be still in place but loose, and numerous blisters were in evidence. A closer inspection showed that the interior of this tank was so badly pitted under the coating that any further attempt to use the tank was inadvisable. This tank was therefore discarded and a new galvanized tank ordered and set up at considerable expense and inconvenience. In April, 1946, another dehydrating tank installation was made on an adjoining lease. This installation consisted of a 1,500 bbl. 3-ring galvanized tank with two sets of flat steam coils 12 in. and 24 in. up from the bottom. In September, 1947. seventeen months after installation. salt showed up in the boiler feed water. When the dehydrating tank was opened and cleaned, the steam coils were found to be badly pitted — several holes having penetrated through the wall of the pipe. New coils were installed.

Jan 1, 1950

By Harold W. Scott

Geological Engineering is now a recognized curriculum in most of the mining schools in United States. Graduates of these schools are scattered over the face of the earth, participating in exploration and mining enterprises of diverse character. They are engaged in the mapping of new mineral deposits, in the extension of old deposits, the estimation of reserves, microscopic analysis, and in the direction of exploitation and conservation of man's natural resources. The training of men qualified to carry out these technical phases of modern industry has fallen essentially to the mining schools. For the most part they have met the demand for technically trained men in the mineral industries. Schools Offering Geological Engineering Degree The mining schools have passed through the early stages of their development and at the present offer varied curricula covering the fields of geological engineering, mining engineering, and metallurgical engineering. Usually a B.S. degree is offered in any of these three fields. However, .there has been some tendency of recent date on the part of the Engineers Council for Professional Development to question the validity of a B.S. degree in Geological Engineering. The of this paper is to examine the curricula as offered in the mining schools, to evaluate their engineering content, and to propose minimum requirements for the degree of Geological Engineering in the mining industry. The curricula of eight institutions that offer the degree of B.S. in Geological Engineering or Mining Geology have been studied (Table 1). All except one of these schools are in or near mining districts and occur west of the Mississippi River. They are all state-supported institutions that have come into existence because of the state's need for technically trained men. A graduate from .a mining school is called upon to perform many duties of a technical nature. His initial task may be to make a geological map of a mine or the surface above, but before the map is finished he may be asked to take over the responsibility of getting the ore "on top." And finally, he might find it essential to know how to mill the ore. Certainly this requires technically trained men and the mining schools are essentially the organizations to do the job. The departments of geology in these schools are training geological engineers. Field Of Geology If we were to accept the opinions of some writers, we would be forced to conclude that all geology departments offer only a "dilettante" variety of subjects.

Jan 1, 1944

By Ben F. Dickerson

Mineral exploration programs have often experienced mismanagement in the decision-making process, and these errors have consequently resulted in stockholder losses. Unfortunately, the events leading to these errors are little known and rarely studied, since managers aren't prone to publicizing their mistakes. However, a bit of magnified hindsight may serve to identify some of the problems. It is interesting to note that there does not seem to be a generally agreed-upon definition of the role and function of exploration management. Several articles have addressed this subject, written by both academic and industry exploration personnel. Two apparent thought trends can be observed: First, the theoreticians insist that modern scientific management principles can be directly applied, without modification, to mineral exploration. However, when one searches for the rules, the proponents rapidly retreat behind the computers and talk learnedly of management information systems and game theory.

Jan 6, 1978

By E. J. Dulis, G. V. Smith

AS reported several years ago,' nitrogen may be taken up from the atmosphere by austenitic Cr-Ni steels during creep or creep-rupture tests. This was indicated by chemical analysis and by the appearance of a new microstructural phase, or phases, tentatively identified as chromium nitride (S), at the surface or at the intergranular cracks associated with fracture. The nitrogen pickup was observed to be dependent on time, temperature, and deformation. In a more recent investigation, a sample was obtained in which there was sufficient of the precipitate to suggest that it could be readily identified by X-ray diffraction. This sample had been taken from a 1/4 in. diam creep-rupture specimen of annealed, type 304L stainless steel of the following initial composition: C, 0.03 pct; Mn, 0.65; P, 0.010; S, 0.019; Si, 0.54; Cr, 19.50; Ni, 12.02; N, 0.031; and Al, 0.005. The specimen had ruptured after 10,470 hr at 1500°F (2000 psi). In this case nitrides were distributed across the whole section of the sample, Fig. 1. The precipitate occurred both at the grain boundaries and within the grains; the latter precipitate had in some cases the appearance of pearl-ite, and in others was distinctly Widmanstatten. Chemical analysis of the sample after test showed 0.64 pct "soluble" nitrogen (soluble in 1:1 hydrochloric acid: water) and 0.18 pct "insoluble7' nitrogen (insoluble in the hydrochloric acid solution but dissolved by fuming sulphuric acid). For identification of the precipitate by X-ray diffraction, the matrix in the surface layer of the specimen was dissolved by prolonged attack in an alcoholic solution of picric and hydrochloric acids. The appearance of the specimen surface after such etching is shown in Fig. 1c. The diffraction pattern of the surface-concentrated precipitate was obtained with a recording spectrometer in both the forward and back-reflection regions (the latter by adapting a special fixture to the conventional X-ray unit). The observed X-ray diffraction lines, Table I, show the presence of Cr,N and CrN; the agreement with interplanar spacings calculated from reported data2,3 is quite good. Since it has been suggested' that CrN dissolves only in concentrated sulphuric acid, whereas Cr2N dissolves in dilute hydrochloric or sulphuric acids, an effort was made to distinguish between the two nitrides. This proved possible, inasmuch as etching in a dilute solution of hydrochloric acid gave a sample in which microscopic examination showed that much of the Widmanstatten-pearlitic precipitate within the grains had been eaten out, leaving the grain boundary precipitate in relief, and which, when examined by X-ray diffrac-

Jan 1, 1953

By Norman Weiss

Most papers on xanthate have dealt with principles rather than practice. On the assumption that many millmen are interested in knowing where and in what manner the xanthates are being used in mills other than their own, this paper will summarize the results of a recent survey of North American plants. A brief background story and a description of the xanthates will be followed with the results of that survey; then a few observations will be made on storage, feeding, and ore testing. The first xanthate was made in 1822 by Zeise of the University of Copenhagen. With commendable scientific detachment (or perhaps a bad cold) Zeise ignored a more pervading quality of the substance and named it for its color, after the Greek word "xanthos," meaning yellow. During the first 80 years of its recorded existence xanthate found use only in small quantity as an insecticide; after the turn of the century there was some further demand for it in the vulcanization of rubber. It was not until 1922, by coincidence the centennial of Zeise's discovery, that C. H. Keller of San Francisco, seeking sul-phidizing agents, recalled xanthate in connection with his experience years earlier when he had seen this material used in Europe to combat grape phylloxera. His successful tests with the new flotation reagent culminated in the basic xanthate patent (U. S. 1,554,216) in 1925. In the minds of many metallurgists the introduction of xanthate as a flotation reagent is identified with the beginnings of alkaline circuits, the first use of chemical collectors, and the beginning of selective flotation. Actually, these preceded xanthate by a number of years. The alkaline circuit in lead-zinc flotation was introduced by Lyster as early as 1912. In 1922 Sheridan and Griswold made their momentous discovery (Timber Butte) that alkali cyanides and zinc sulphate effectively inhibited the flotation of pyrite and sphalerite in pulps made alkaline with sodium carbonate or bicarbonate. The use of lime to retard pyrite in copper flotation began within two years after Ralston directed attention to its possibilities in 1917. These were the beginnings of modern selective flotation, which was practiced successfully on copper-iron ores at Nacozari in 1922, and at Inspiration, Cananea, and others only shortly afterward. In the lead-zinc mills, selective flotation was of even greater economic importance at that time. The Sunnyside plant of U. S. Smelting, Refining, and Mining Co. used the process earlier than 1920, and Consolidated, Timber Butte, and others soon followed. As a chemical collector xanthate was relatively a latecomer, for the Corliss patent of 1917 covered the first of these, alpha-naphthylamine, and the Perkins patent of 1919 the second, thiocarbanilid. Both of these were in extensive use before Keller's xanthate made its commercial debut in 1923. There is general agreement, nonetheless, that the introduction of xanthate was

Jan 1, 1949

By P. E. McKinney

Developments in engineering during the past decade, particularly as applied to marine construction, mining machinery and other purposes in which corrosion offers a serious problem, have created a large demand for a non-ferrous metal highly resistant to corrosion and at the same time useful in general construction work as a substitute for steel without materially decreasing the factor of safety or increasing the weight of the various parts over that ordinarily used in the case of mild steel. To obtain the combination of desired properties many compositions have been proposed and used with excellent success, but at the present time probably the most popular and most widely used combination is the non-ferrous alloy commonly called manganese bronze. This is nothing more than a high brass to which have been added, by the proper method of alloying, comparatively small percentages of aluminum, iron, or manganese with the definite purpose in view of strengthening the alloy and rendering it more dense and close-grained than the average yellow-brass casting. In the manufacture of manganese bronze a great deal has been said about the importance of using only the highest grades of raw material and the beneficial or detrimental effects, as the case may be, of various impurities, as well as the importance of adding the ingredients according to various formulas proposed; but in most of these cases the literature on the subject has dealt principally with the manufacture of this alloy from virgin metals and raw materials of the highest purity. It is the purpose of this paper to deal particularly with the possibilities that lie in the proper development of methods for manufacturing such an alloy by more economical methods than those which have usually been discussed in other literature on the subject. Shortages have recently existed in raw materials needed for many products entering into the various branches of engineering work, particularly the non-ferrous metals, and during the next few years of reconstruction the country will be flooded with many

Jan 1, 1919

By S. E. Bretherton

Discussion of the paper of S. E. BRETHERTON, presented at. the San Francisco meeting, September, 1915, and printed in Bulletin No. 104, August, 1915, pp. 1595 to1599. ANTON EILERS, Brooklyn, N. Y. (communication to the Secretary*). While the advantages in the use of high-line siliceous slags in lead smelting which Mr. Bretherton discusses in this paper are obvious under certain economical conditions, he gives me credit for the introduction of such slags when it does not belong to me. It is true I did considerable experimental work, off and on, for the purpose of finding such slags, while at the Germania in 1877 and 1878, but I did not have occasion to introduce any such slags for regular work, because I had no ores which fitted the economical conditions for using high silica and high lime, except in isolated cases for very brief periods. On the contrary, the ores I had to treat were mostly very ferruginous and very low in silica, so that, economically, I was compelled to run nearly always on slags, which allowed me to use the abundant flux I had without cost. It was August Raht who first had occasion to establish and use for long periods a slag high in silica and line, and low in iron. This was when he was confronted with the task of smelting the. Horn-Silver ores at the smelting works at Franklin, Utah, with as little expenditure for fluxing material as possible. I was at that time in Leadville, Col., where, in the new works I had built, the Billings and Eilers smelters, I had occasion to use profitably many slags, but never anything as high in the earthy bases and in silica as Mr. Raht had to use.

Jan 12, 1915