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By J. E. Kirby, L. B. Schnitz, H. E. Stamm III

The production history of a gas-cap-drive reservoir was reproduced by calculations, and predictions were made for operations under primary depletion, pressure maintenance by gas injection, and pressure maintenance by water injection. Although the general equations used in this analysis have been available to the industry for a number of years, the procedure has not had extensive use because of the unusually large time requirements for developing numerical results. The use of digital computing equipment for processing the calculation work generally reduced the time usually required for an extensive analysis of this type. Calculation techniques were developed that were equally applicable for solving the gar-cap-drive problem, whether digital computing equipment or desk calculators are used. These techniques are outlined and the procedures are illustrated by the field problem. INTRODUCTION The analysis of a gas-cap-drive res-ervoir requires the simultaneous solution of the volumetric balance1 and displacement2 equations. Equations for the analysis of combination drive reservoirs were presented by Wooddy and Moscrip in a previous paper." These equations permit the evaluation of possible operating processes in order that the optimum method of pro- ducing the reservoir may be determined. Although these equations represent the basic technique known for the detailed analysis of gas-capdrive reservoirs, the calculation processes are quite complex and time consuming; hence, the procedure has not had extensive use. Recently, these equations were satisfactorily applied with the aid of a digital computer to investigate the completion history of a gas-cap-drive reservoir under the following operating methods: primary depletion, depletion under full pressure maintenance by gas injection, and depletion under full pressure maintenance by water injection. The use of digital computing equipment substantially reduced the time necessary for making the computations and permitted a more concise investigation of the reservoir's depletion history than was possible when the desk calculator was used. This more rigorous investigation also permitted a detailed analysis of the calculation procedures necessary in the solution of the gas-cap-drive problem. This paper outlines the procedure of analyzing a gas-cap-drive reservoir and illustrates the process with an actual field problem. CHARACTERISTICS OF THE RESERVOIR ANALYZED Production in the field under consideration is obtained from a Frio formation of Oligocene age at a depth of approximately 5,740 ft sub-sea. The accumulation, which is bounded on the flanks by strand lines, is semirectangular in shape with gentle narrowing toward the base of the structure as shown by the sand limits and completion map in Fig. 1. The reservoir development indicates an oil column of 319 ft that is defined by gas-oil and oil-water contacts. Basic data relative to the characteristics of the formation and the formation fluids are shown in Table 1. The formation exhibits considerable shaliaess and thinning near the oil-water contact indicating that little or no benefit will be received from natural water influx. This is substantiated by the fact that wells completed near the original oil-water contact have not produced water. A sizeable gas cap is present; however, considerable faulting is in evidence, and it is believed that only a limited portion of the gas cap will aid in oil displacement and pressure maintenance. Although the reservoir was in an initial stage of depletion, it was believed that as soon as the equilibrium gas saturation in the oil zone was exceeded and a number of upstructure wells were invaded by the expanding gas cap, the resulting high gas-oil ratio production would rapidly dissipate the natural drive and lead to limited oil recoveries and inefficient reservoir operation. This analysis evaluated the effectiveness of the primary displacement mechanism and

Jan 1, 1958

By Charles N. Bell

The Telluride mining district of southwestern Colorado is defined by the 37" 45' and 38" parallels of latitude and 107" 45' and 108" meridians of longitude. Telluride was never a boom camp, but has had a steady growth. In recent years, notwithstanding the business depression of 1920, the business has been the same as in normal years. The first prospector is said to have appeared in 1875, in which year locations on the Smuggler vein were made. Shipments were made in 1877 and 1878, and in 1879 milling the ores was attempted. While the district produced high-grade ores, it did not become important until 1890, when the Rio Grande Southern R. R. was completed from Ridgway to Telluride. The railroad has since been extended to Durango. In the fall of 1896, 400 stamps were in operation, and the annual production was $3,000,000.00, two-thirds of which was gold. The total production from 1875 to 1923 was: gold $58,274,527; silver 41,-830,920 oz., valued at $31,016,893; copper 15,258,866 lb., valued at $2,533,291; lead 166,056,484 Ib., valued at $8,324,910; zinc 18,141,182 Ib. valued at $1,323,787; or a total production of $101,473,408. All claims are held in fee. Most of them are 1500 by 300 ft. but claims located within the last few years are 1500 by 600 ft. General supplies are obtained at Telluride, Denver, and Salt Lake. The largest mines are within 6 miles of the town of Telluride. Denver is 422 miles and Salt Lake is 439 miles, by rail, from Telluride. One-half of the distance to Denver and one-sixth of the distance from Telluride to Salt Lake is by narrow-gage railroad. The labor is efficient. The best miners are Italians and Austrians, then Slavs, Greeks, and Mexicans follow in the order mentioned. There are no labor unions. There are no serious mine pumping problems, the drainage being through adits. The Tomboy and Smuggler companies pump water from their reservoirs, the former for milling and domestic purposes and the latter for milling, power, and domestic purposes. BIBLIOGRAPHY A partial bibliography of the Telluride District is: Geologic Atlas Telluride No. 57; Preliminary Report on the Mining Industries of the

Jan 1, 1925

By Harry E. Cross

Kiln Products commissioned a Waelz kiln 4 metres in diameter by 75 metres long, in South West Africa in March, 1969, to recover nine in a form suitable for the production of electrolytic zinc. The raw material consists of a mixture of zinc silicate concentrates and zinc rich tailings purchased from an adjacent zinc mine - the mixture containing 20% to 25% zinc. The chemical composition of the ore is tabulated and the initial test results are described. Due to the comparatively low temperature at which the ore starts softening the kiln has certain unusual features to enable the temperature to be controlled within the necessary limits. A detailed description of the kiln, the starting-up problems and present operating conditions and results are presented.

Jan 1, 1970

By L. E. Mannion

Sodium carbonate (soda ash) is one of two principal commercial alkalis. Its principal competitor is sodium hydroxide. The use of sodium carbonate is recorded in ancient Egypt, where naturally occurring brines and solid salts provided impure soda for early glassmaking. Until the 19th century, soda ash (as well as potash) was recovered mainly by leaching wood or other plant ashes. In 18th-century Europe, for example, leaching seaweed ash with hot water produced a brown laundry lye. One of the better grades of this material was a Spanish product, barilla, which analyzed 24 to 30% Na2CO3 (Hou, 1942). The modern chemical industry was born in 1691 with the LeBlanc process for making sodium carbonate from salt, sulfuric acid, and lime. English industry used this process extensively in the 17th and 18th centuries. The next major advance was in 1863, when Ernst Solvay devised the ammonia-soda, or Solvay process. The first of many Solvay plants was built in 1874. These supplanted the LeBlanc method and dominated worldwide soda ash production until 1974, when mined sodium carbonate became predominant. Although considerably less important until recently, natural sodium carbonate deposits historically have supported small soda ash operations throughout the world. Shortages during World War II stimulated production of "natural" soda ash from such deposits, particularly at Searles Lake, CA and Lake Magadi, Kenya. More spectacularly, increased production from the vast trona deposits in Wyoming has virtually supplanted the Solvay process in the US. Principal producers of natural soda ash as well as the character of the source deposits are listed in Table 1. [ ]

Jan 1, 1983

By F. George, W. Tice, M. Salkind

It was found that Al-A13Ni could be readily cold rolled perpendicular to but not parallel to the whiskers. Reductions of more than 98 pct were achieved without cracking by rolling perpendicular to the whiskers, whereas extensive edge cracking was noted after only 15 pct reduction when rolling parallel to the whiskers. The longitudinal and transverse tensile strengths were nearly doubled, and the longitudinal yield strength more than tripled by cold rolling 50 pct in a direction perpendicular to the whiskers. The whiskers exhibited some waviness (elastic bending) as a result of cold rolling, but at very high reductions (greater than 75 pct) whisker fracture and misalignment became significant. A fine dislocation substructure in the matrix consisting of cells attached to the whiskers was pro -duced by cold rolling. Most of- the substructure was readily removed by a 1-hr anneal at 500°C. Cold rolling was found to substantially reduce the thermal stability of the microstructure at 610°C but did not affect the stability at 500°C. FIBER and whisker reinforced composite materials promise significant improvements in properties over conventional materials. Before they find wide use, however, it will be necessary to understand the response of these highly anisotropic materials to common metalworking processes. Most of the nonmetal-lic fiber reinforced materials have very low elongations (a few pct or less) in the direction of fiber alignment. Thus, metalworking techniques such as rolling and forging would not be as broadly applicable to these materials. This investigation was initiated to determine how a composite system consisting of Al3Ni whisker reinforced aluminum responded to rolling, what changes in the microstructure occurred, and the effect of deformation on the mechanical properties. The composite material studied was produced by unidirectional solidification of the A1-Al3Ni eutectic alloy'-7 and consisted of 10 pct by volume of aligned whiskers of Alai in a matrix of aluminum. It should be pointed out that this system is not representative of all composite materials, and the results will therefore not be universally applicable. The A1-Al3Ni system is characterized by: 1) A strong fiber-matrix interfacial bond 2) A ductile matrix 3) A sufficiently low fiber content to allow significant plastic flow between fibers 4) Strong, completely elastic whiskers (tensile strength 400,000 psi, elastic modulus = 20 X 106 psi.1 These factors allow the material to be readily rolled perpendicular to the fibers. If the fiber-matrix bond were not strong, such a weak interface could fail during rolling. A measure of the ability of a composite to be rolled in the transverse direction can be obtained from noting the transverse tensile behavior. In the case of Al-Al3Ni,2 there is considerable ductility (15 to 30 pct). In the case of boron filament reinforced aluminum, for example, the transverse elongation is less than 1 pct,8 and the material could probably not be cold rolled as readily in that direction. EXPERIMENTAL PROCEDURE 3-in. diam ingots of A1-A13Ni eutectic were unidi-rectionally solidified in graphite crucibles. The starting materials consisted of 99.99+ pct pure nickel and aluminum, and the pure eutectic ingots were made with 6.2 wt pct Ni. The unidirectional solidification process (described in detail elsewhere1-3) consists of preparing a master heat of eutectic composition, remelting, and withdrawing the ingot vertically downward through the heat source at a controlled rate so that plane front solidification proceeds upward at a constant velocity. The resulting microstructure consists of 10 pct by volume of whiskers of very high aspect (length to diameter) ratio. The fiber lengths have not been measured because of the difficulty of detecting fiber ends9 but exceeds 104. There is some possibility that the fibers may be continuous within one grain. Flat sheet specimens 2¾ in. sq and approximately 0.2 in. thick containing whiskers parallel to the plane of the sheet and to one edge were used for this study. A1-A13Ni exhibits either a rod-like (high solidification rates) or a blade-like (low solidification rates) whisker morphology,1,3 and both types were studied. Rolling was accomplished using a two-high rolling mill at a speed of approximately 10 fpm. The rolling direction was either parallel to or perpendicular to the direction of growth (direction of whisker alignment). Reductions of from 0.002 to 0.03 in. per pass were used with the most common value being 0.005 in. per pass. Cold rolling of Al-Al3Ni to more than 98 pct reduction in thickness was accomplished with no intermediate anneals. In addition. a series of speci-mens was cold rolled 97 pct with a 1-hr, 500°C anneal in air after each 50 pet reduction. Tensile testing was accomplished using a Tinius-lsen four screw testing machine. Flat sheet specimens + in. wide and between 2 and 2; in. long with the thickness dependent upon rolling reduction, were used. The gage section was in. wide and 1 in. long. Strain was measured using a clip-on LVDT extensome-

Jan 1, 1970

By H. M. Shepard

THE copper industry operated at high capacity throughout 1947, with no serious tie-ups in operation as was the case in 1946, when almost the entire industry was shut down by a four-month strike. Refined copper production in the United States averaged 94,250 tons for the first eleven months and deliveries to domestic consumers, including foreign copper for domestic consumption, averaged 114,000 tons per month. On April 29 the import duty of 4d per lb was suspended until March 31, 1949. Copper prices fluctuated considerably for a short time thereafter. Over the year the price of domestic electrolytic copper at refineries on the Atlantic seaboard advanced from 19.225¢ on Jan. 2 to 21.200d on Dec. 24.

Jan 1, 1948

By H. A. Schwartz, W. Kenneth Bock

In this paper it is shown that when the tensile strength of a given steel in various states of heat-treatment is plotted against its elongation, a straight line results. The equation of this straight line can be computed with considerable accuracy from its chemical composition. The appropriate equations are given. The logarithm of the slope of the tensile-strength locus is shown to be proportional to the cumulative effect of the total alloy addition and the vosition of the line to be directly proportional to the cumulative effect of the alloy content. It is further pointed out that heat-treatment is more effective than composition in determining yield ratio. The latter enters mainly by its effect on hardenability, which is briefly discussed. Reduction of area and Brinell number are given some incidental attention. The data are applicable only to steels that have been normalized and/or quenched. The steels, if normalized, may or may not have been tempered. If quenched they must have been tempered at or above 4oo°C. (75o°F.). Introduction Cast steels vary in composition and frequently are used in various states of heat-treatment. It is obviously important to be able to predict the compositions that might accompany specific engineering properties by suitable selection of heat-treatments. For cast steels, which are of necessity produced heat by heat in accordance with the particular requirements of the castings to be poured, there has been, happily, much less tendency to standardization than for rolled products, whose destination is not necessarily known when particular ingots are made or rolled. It is of distinct advantage to the steel foundry-men to be able to make steel of given properties, using alloys that can be recovered from scrap, or most conveniently or cheaply bought, rather than a particular formula adopted in the interest of standardization. The heat-treatment appropriate to securing a given result in a given steel is well known to be closely related to composition. For example, molybdenum steels are not much softened by tempering except at rather high temperatures. Highly alloyed steels are "air-hardening," and on cooling in air behave like carbon steels that have been quenched. With these matters, we do not concern ourselves in this paper, although we recognize their importance. The entire picture evidently will be very complex and can be brought within accurate understanding only if our knowledge of test results can be coordinated in terms of general principles.

Jan 1, 1944

By H. A. Schwartz, W. Kenneth Bock

In this paper it is shown that when the tensile strength of a given steel in various states of heat-treatment is plotted against its elongation, a straight line results. The equation of this straight line can be computed with considerable accuracy from its chemical composition. The appropriate equations are given. The logarithm of the slope of the tensile-strength locus is shown to be proportional to the cumulative effect of the total alloy addition and the vosition of the line to be directly proportional to the cumulative effect of the alloy content. It is further pointed out that heat-treatment is more effective than composition in determining yield ratio. The latter enters mainly by its effect on hardenability, which is briefly discussed. Reduction of area and Brinell number are given some incidental attention. The data are applicable only to steels that have been normalized and/or quenched. The steels, if normalized, may or may not have been tempered. If quenched they must have been tempered at or above 4oo°C. (75o°F.). Introduction Cast steels vary in composition and frequently are used in various states of heat-treatment. It is obviously important to be able to predict the compositions that might accompany specific engineering properties by suitable selection of heat-treatments. For cast steels, which are of necessity produced heat by heat in accordance with the particular requirements of the castings to be poured, there has been, happily, much less tendency to standardization than for rolled products, whose destination is not necessarily known when particular ingots are made or rolled. It is of distinct advantage to the steel foundry-men to be able to make steel of given properties, using alloys that can be recovered from scrap, or most conveniently or cheaply bought, rather than a particular formula adopted in the interest of standardization. The heat-treatment appropriate to securing a given result in a given steel is well known to be closely related to composition. For example, molybdenum steels are not much softened by tempering except at rather high temperatures. Highly alloyed steels are "air-hardening," and on cooling in air behave like carbon steels that have been quenched. With these matters, we do not concern ourselves in this paper, although we recognize their importance. The entire picture evidently will be very complex and can be brought within accurate understanding only if our knowledge of test results can be coordinated in terms of general principles.

Jan 1, 1944

By Heinrich 0. Hofman

A T THE meeting of the Board of Directors on June 24, Prof. Heinrich O. Hofman was elected an honorary member of the American Institute of Mining and Metallurgical Engineers. Professor Hofman is best known to the world at large for his publications, and in this respect he is to this generation what Schnabel was to the previous one. The first edition of Professor Hofman's "Metallurgy of Lead and Desilverization of Base Bullion"; was published in 1893; the fifth edition in 1898. In 1913, he published his work on "General Metallurgy;" this was followed by "Metallurgy of Copper" in 1914, and a revised and enlarged edition of the "Metallurgy of Lead" in 1918. "Metallurgy of Zinc and Cadmium" is now in press. He also published, through the Massachusetts Institute of Technology, "An Outline of the Metallurgy of Iron and Steel" for students' use. Since the founding of "Mineral Industry" in 1892, he has been continuously the annual contributor on the metallurgy of lead, and all Institute members know that his contributions to the TRANSACTIONS have been liberal in the extreme. It is through this medium that the results of the extensive research work, which he has always carried on in connection with his work at the Massachusetts Institute of Technology, have been published. Of the greatest importance are his papers dealing with the formation temperatures of slags, but many other metallurgical subjects have been covered.

Jan 1, 1921

E. E. THUM,* Salt Lake City, Utah (written discussion?).-While the present paper is confined exclusively to the microstructure of fusion welds, it may be of interest to draw attention to certain appearances existing in resistance welds such as spot or butt-welded joints produced by the Thomson process. For instance, a butt weld between two pieces of carbon tool steel (carbon about 0.90 per cent.) will show concentric ellipsoids of the various materials from pearlite to martensite. The surfaces of demarcation are quite well defined, the center of the ellipsoid being at the intersection of the axis of the piece and the plane of the weld. Often these unannealed welds show a troostitic center; evidently this core was not quenched as rapidly as the surrounding shell. Such specimens are beautiful samples for instruction purposes. An annealed butt weld of this kind will show a very well defined central ellipsoid of decarburized, materials. It is interesting to consider the reason why this change takes place. It must be understood that the heat is on the metal for a very short time, possibly 30 sec. It is therefore evident that the decarburization, or migration, of the carbon takes place with extreme rapidity. Since no blowholes are evident in a well-made butt weld, the deoxidizing air and the products of combustion must migrate with the highest speed; second, the carbon might migrate back into the stock; or, last, a large proportion of the pearlite may be extruded with the hot metal, which forms a fin at the plane of weld. Examining these possibilities in detail, it is not probable that such deep-seated decarburization, extending with maximum effect to the very center of a 2-in. round bar, is done by reaction with the oxygen of the air. This would postulate entrance of oxygen and egress of carbon oxides in large quantity without leaving behind traces in the form of oxides or

Jan 5, 1919

By Donald A. Brobst

The minerals barite (BaSO4) and witherite (BaCO3) are the chief sources of the element barium and its compounds needed for many industrial processes and products. Barite, the principal ore mineral, is found the world over and is abundant and widely distributed throughout the United States.3 Witherite is much less common than barite, though more desirable in many ways as a raw material for the production of barium chemicals. England is the chief producer of witherite. Witherite is not mined in the United States at the present time, but it has been mined with barite from a deposit at El Portal, California. Barite is also called barytes, tiff, cawk, or heavy spar. Ordinarily it is a heavy mineral that crystallizes in the orthorhombic system. It is colorless, white, or gray, and transparent to opaque. In some deposits barite is black, yellow, brown, red, green, or blue because of included impurities. The streak is white and the luster vitreous to resinous or pearly. The specific gravity of pure barite (65.7 pct BaO and 34.3 pct SO3) is calculated to be 4.5, but inclusions and impurities in natural barite may reduce this value considerably. Well-formed crystals are generally tabular and have three cleavages. The barite of many deposits, however, has an uneven fracture and an apparent cleavage caused by separation along planes between successively deposited layers. The hardness is 2.5 to 3.5 on Mohs' scale. Commercially the terms "hard" and "soft" are used to refer to ease of grinding. Barite is relatively insoluble in water and acid, and thus can be used as a chemically inert material. Witherite, the natural carbonate of barium (77.7 pct BaO and 22.3 pct CO2), crystallizes in the orthorhombic system. The fracture is uneven and the luster is vitreous to resinous. The hardness is 3 to 3.5. The specific gravity of the pure mineral is calculated to be 4.29. It is transparent to opaque. The color is ordinarily white, gray, yellow, brown, or green. Geology and Distribution of Deposits Workable deposits of barite are widely distributed throughout the world in many geologic environments in sedimentary, igneous, and metamorphic rocks. Most deposits can be classified into three main types: (1) vein and cavityfilling deposits; (2) bedded deposits; and (3) residual deposits. 1. Vein and cavity-filling deposits are those in which barite and associated minerals occur along faults, gashes, joints, and bedding planes, and in breccia zones and solution channels. They also occur in various collapse and sink structures in limestone. Sharp contacts of the veins and cavity fillings with wall rocks are common. Barite cements fault and collapse breccia by replacement of the matrix or by filling voids. Large-scale replacement of the wall rocks beyond ore-controlling structures is rare. Barite in vein and cavity filling deposits is generally dense, "hard," and white to gray. Associated minerals are fluorite, calcite, ankerite, dolomite, quartz, and many sulfide minerals, especially pyrite, chalcopyrite, galena, and sphalerite. Gold, silver, and rare earth minerals occur with barite in some deposits in the western United States. Barite is also a gangue mineral in metallic ore deposits but production as a byproduct from such deposits will be affected by many economic factors. The host rocks are igneous, sedimentary, and metamorphic rocks of pre-Cambrian to

Jan 1, 1960

By O. H. Eschholz

THE electrostatic process of fume precipitation is an excellent example of the successful application of scientific knowledge to an industrial operation. Originally proposed for the precipitation of sulphuric acid mists, it has been extended until at present there is practically no fume carrying gas to which the method cannot be applied. Among the more common applications are: the recovery of non-ferrous smelter flue-dust, iron blast-furnace dust, cement dust, and potash fume. It should be borne in mind that the process is restricted to the precipitation of suspended particles, either liquid or solid, and does not separate gaseous constituents. However, -by proper temperature control, mixtures of vapors having different temperatures of condensation to either solids or liquids may he selectively precipitated. The process consists essentially of subjecting suspended particles, including those too minute to be effectively acted upon by centrifugal or gravitational forces, to such an electrical force that they are driven from the gas stream, acting as a conveyer, and deposited upon a suitable receiving surface. This directional impulse is obtained front the interaction of charged particles and an electrostatic field of definite intensity gradient existing between two dissimilar electrodes, known as discharge and receiving electrodes. In principle, the equipment is equally simple. As shown diagrammatically in Fig. 1, it consists of: (1) A source of high-potential direct current, requiring: (a.) Source of alternating-current energy. (b) Means of transforming from tow voltage to high voltage. (c) Means of converting alternating to direct current. (2) Precipitation chamber having: (a) Transmission tubes for fume-laden gases. (b) Suitably designed and disposed electrodes. (c) Means for affecting removal of deposited solids.

Jan 8, 1918

By J. W. Halley, G. L. Plimpton

BECAUSE of the two distinct stages in the solidification of rimmed steel, segregation in the rimmed ingot is more complex than that in the killed or semikilled ingot. In the earlier stage, chemical reactions, resulting in evolution of gas and vigorous stirring of the metal, effect a degree of negative segregation unique to rimmed steel. The composition of this zone constitutes the principal quality advantage of this type of steel. In the later stage of solidification, after the evolution of gas has ceased, the segregation follows the general pattern of a more completely deoxidized steel. However, the composition of the liquid remaining after the first solidification stage varies markedly from that of the original melt, some constituents having been partially removed as reaction products while the concentration of others has been intensified by rejection from the metal solidifying in the first zone. The aim, from the standpoint of segregation, in rimmed steel of high quality is to effect a maximum negative segregation in the rim zone without excessive concentration of undesirable elements at the center of the ingot. To achieve this aim, the composition of the melt may be varied and the furnace and pouring practice may be adjusted within certain limits. It is the purpose of this study to discuss segregation in rimmed steel from the standpoint of the mechanisms that produce it and to survey the phases of open-hearth practice that influence those mechanisms. MECHANISMS PRODUCING SEGREGATION The mechanisms that determine the degree of segregation in the rimmed ingot are closely interrelated, making it difficult to select the primary factors and to determine a satisfactory order for presenting them. For instance, the question of sulphur segregation is relatively simple, since sulphur is not directly involved in chemical reactions in the ingot; but its concentration in the rim zone is dependent not only on its original analysis in the melt, its segregation coefficient, and the freezing rate, but also on the rate of its removal from the impure film on the solidifying surface. This washing action involves all the factors (such as freezing rate, the carbon-oxygen product, pressure, etc.) that determine the rate of gas evolution and hence the efficiency of film removal. Sulphur distribution between the rim and core is affected by the volumetric ratio between the two zones, and its segregation in the core is a function not only of the freezing rate of the core but also of all the foregoing factors that determine its concentration in the metal when solidification of the core starts. To simplify the presentation, it is proposed to treat the mechanisms affecting segregation independently in this section, reserving a discussion of their over-all effects for the section in which actual segregation data are given. The factors affecting segregation will be treated in the following order: (I) differential solidification, (2) removal of constituents as

Jan 1, 1944

By S. H. Ash

More than 100 minerals are mined and processed in the U. S. Management and labor have negotiated wage-scale agreements that have balanced wages and affected cost of labor in such a manner that comparisons can be made of transportation costs. Transportation of materials underground has become of vital importance. This report describes underground haulage methods and equipment, presents cost analyses, and discusses future plans for underground transportation in metal mines. It does not cover hoisting in shafts or slopes by cage, skip, or cars. Advancements have been made by the metal mining industry in lowering transportation costs in several mines, making it possible to mine orebodies or portions of orebodies not considered economically recoverable a few years ago. Numerous reports have been written on transportation at metal mines; this report covers recent haulage at some representative mines throughout the U.S. The term metal mine is used to include all noncoal mines from which up-to-date information was obtainable.

Sep 1, 1956

By L. L. Davis

Current research by the US Bureau of Mines to develop technology for improving efficiency and productivity in metal/nonmetal mines is described. The research program addresses a wide variety of problems associated with each of the major categories of mining: underground mining, surface mining, m situ mining, and premining investigations. An overview of the Bureau's research activities is given with emphasis on underground mining. In particular, two innovative and promising concepts currently under development are described: a unique shaft sinking system that uses an impact hammer for rock fragmentation, and a low-profile portable crusher for underground hard-rock applications.

Jan 1, 1982

By John E. Willson, Ben L. Seegmiller

A portable electronic instrument was designed and constructed to detect unknown stress magnitudes in rocks. The principle used to detect stress is based on the propagation velocity method. This method allows the stress in a rock subjected to a load of unknown magnitude to be determined, provided that the wave velocity-stress relationship for similar rock is known. This is accomplished by measuring the travel time of longitudinal mechanical waves passing between two points a set distance apart in a rock. The velocity of the wave is calculated and the stress determined from the wave velocity-stress relationship. If the sending and receiving transducer spacing is constant, a time vs. stress relationship rather than the velocity-stress relationship may be used. The method is nondestructive and tests can be made without drilling or otherwise disturbing the rocks. The first studies undertaken in the United States to determine stress in rocks using propagation velocity techniques were reported by Obert1,2 in 1939 and 1940. The Soviet Union first reported using propagation methods to study rock pressures in 1951.8 Success of the method led to the development of a pulse-type ultrasonic seismoscope4 in 1953. Using this instrument, Ivanov and Betaneli5,6 in 1963 succeeded in devising and testing under field conditions a method of investigating coal pillar stresses. In 1967 Osipova7 reported results of similar studies in the Nakhichevan salt mines. In France, Tincelin8 has used the propagation velocity method to study the stress distribution in iron ore pillars. Uhlmann9 has investigated stresses in salt and potash pillars in Germany, using velocity techniques. Determination of uniaxial stress by propagation velocity methods is limited to rocks which have readily detectable wave velocity-stress variations. The present stress detection instrument is restricted in application to rocks which have a velocity change under stress of at least 300 fps. Examples of rocks which meet this requirement are sandstones, coal, and possibly some limestones. Testing of this instrument was limited to a laboratory study and the results may or may not be indicative of what would be found in a field test. A program of field experiments to study the feasibility of using this instrument to determine mine pillar and tunnel stresses is in progress. Instrument Design The instrument has two main components: A probe and a control-display unit. The probe is a hand-held device to which two identical rodlike transducers are rigidly mounted. Coaxial cable connects the probe to the control-display unit which is mounted in an enclosed carrying case measuring 7 % x 9 x 13 in. The instrument is designed so it may be carried and operated by one man. Weight of the probe and enclosed control-display unit is approximately 20.1b. The probe consists of two transducers identical in construction. One transducer is used to convert electronic pulses to mechanical waves and transmit these waves into a rock. The other detects the transmitted waves in the rock and converts them back into electronic signals. The basic element in both transducers is a piezoelectric crystal. The crystal is a disk made of lead titanate zirconate and has a natural resonant frequency of 400 kHz ±1% in the thickness mode. A schematic of one of the two identical transducing elements is shown in [Fig. 1.] A spacing of 6 in. between sending and receiving transducers has been found to be most satisfactory. The control-display unit consists of a pulse generator and a 1-in. oscilloscope. Various electronic devices are used for the power supply, amplification, and calibration. The amplitude of the square wave from the pulse generator can be continuously varied between 0 and +20 vdc. Pulse width can be set at 1, 2, 3, or 4 µsec. The repetition rate of the pulse can have the following values: 50, 75, 100, 150, 200, 250, 300, 400, 500, 750, and 1000 Hz. The oscilloscope delay system allows the travel time of the longitudinal wave passing through a rock to be measured to an accuracy ±0.1 µsec in the range from 0 to 995 µsec. Fig. 2 is a schematic of the various electronic sections in the control-display unit. Laboratory Testing The first step in using the instrument is to develop a velocity-stress or a time-stress curve for the par-

Jan 1, 1972

By Wm. Hamilton Merritt

With the exception of the Vancouver Island coal, all the western coal-fields owe their present development to the completion, in the autumn of 1886, of the Canadian Pacific railroad. While it could not be expected that a very great deal could be accomplished in three years, enough has been done to pretty thoroughly establish the coal-bearing areas and their correspondence with those which have been developed to the south of the boundary along the lines of the transatlantic railroads in the United States. This summer I visited some of the important developments in the coal areas of Washington Territory, largely with the object of being better able to appreciate the corresponding coal-bearing areas in British Columbia to the north. In Western Canada, coal-bearing rocks have been found in three zones: 1. In the plains to the east of the Rocky Mountains and in the eastern flanking ranges, the coal occurs in the Cretaceous formation (including the Laramie). 2. In the interior plateau of British Columbia, the coal is found in the Tertiary formation. 3. On the coast of British Columbia, Cretaceous and Tertiary rocks are found carrying coal, and on the Island of Vancouver the well known Nanaimo coal has been worked for years in the first named formation. In all of these zones, the coals vary from lignites up to higher grades, the factor determining quality being the amount of pressute to which they have been subjected. The intensity of this pressure is generally shown by the disturbance which the coals exhibit, and, in many cases, is almost directly in proportion to the distance of the deposits from mountain ranges. This seems to be also the opinion expressed by Mr. Bailey Willis in connection with his Census Report on the coals of Washington. It has been elsewhere stated

Jan 1, 1890

By Reno H. Sales

EVERY mine manager, mine geologist, and every prospector in the field who appraises the future of mining properties does so on the basis of a theory of ore deposition whether he recognizes this fact or not. Wherever the ultimate value of a mine or prospect is dependent upon undeveloped ore, any estimate by an engineer or geologist necessarily involves a theory of origin of the deposit. In view of these facts the importance of a thorough understanding of the genesis of ore deposits cannot be overestimated. It well may be that the greatness of our country will depend upon finding reserves of natural resources as yet undiscovered. The genesis of ore deposits offers a fascinating field for study and investigation. This is attested by the large number of geologists who have written at length on the subject. For progress made toward a better understanding of ore genesis we owe much to Kemp, Lindgren, Ransome, Vogt, Emmons, Spurr, Graton, and a host of others. Within my own experience, I have attempted to apply in practice the various concepts and theories that have been advanced by these men.

Jan 5, 1954

By H. E. McKinstry

MOVEMENT on a fracture of irregular shape can cause local widening of the fissure and thereby offer freer channelways for circulation of ore-depositing solutions. This influence, coupled with large areas of wall rock available for reacting with ore solutions in brecciated and shattered ground can account for locally active deposition of metals and the resulting ore shoots. Such irregularities in the fracture system may be caused by local variations in the strength of rocks and by pre-existing lines of weakness, especially if these stand at favorable angles to certain components of the fracturing stress. Therefore correct interpretation of the mechanics of fracturing should permit deductions as to structurally favorable places on unexplored portions of the vein system. INTRODUCTION IT has long been recognized that movement on a curved or irregular fault surface is capable of separating the walls in certain portions of the fault, but until very recent years the importance of this mechanism as a factor in localizing ore shoots has escaped proper recognition. A short time ago W. H. Newhouse' presented a careful analytical study of displacements and their corresponding open spaces. For reasons that will be discussed later, it frequently happens that portions of the vein which are favorably oriented are not merely wider but also richer than the average. In many cases the widening with its accompanying richness coincides with very minor changes in the dip or strike of the vein, irregularities that commonly escape notice unless the vein is mapped in detail and a careful geometrical analysis made. While the relationship between the width of the vein and the changes in dip or strike has been recognized as a matter of observation, the irregularities have been accepted as more or less the result of accident. There has been very little effort except in isolated cases to find out the causes of these changes in dip or strike. Yet it is clear that if the causes can be recognized and expressed in terms of geologic structure the geologist will know where to look for repetitions of these favorable conditions either on extensions of the same vein or on adjoining veins. Any lack of understanding of the causes is due to the limitations of our ability to interpret our observations and not to the sheer capriciousness of

Jan 1, 1941

By H. Conrad, E. Stofel

The fracture behavior of 60-deg-oriented sapphire crystals was investigated for both tension and compression. Plastic flow on the basal plane was found to be a factor in reducing the tensile stress required to produce fracture in the temperature RECENT experiments1-' have shown that single crystals of a alumina (sapphire) can deform plastically, particularly at temperatures greater than 1000°C. The effect of this plastic flow on the fracture behavior of sapphire was not established, but range 1100º to 1500ºC. Mechanical twins, both (0001) and (0111) types, were produced by compression in the temperature range 1100" to 1300°C. Cracks propagated more readily along the twin boundaries than in the nontwinned crystal. experiments with other ceramic crystals4'5 have shown that plastic flow can initiate cracks that lead to catastrophic failure. This suggests by analogy that plastic flow might also be an important factor in the fracture of sapphire crystals. A recent experimental investigationS undertaken to determine the mechanism of plastic flow in sapphire provided an opportunity to study the type of fracture produced after various amounts of plastic shear strain. The results of this study of fracture are reported in the present paper. During the course of

Jan 1, 1963