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By Beverley S. Randolph

While our coal-mining practice, in regard to hauling on main roads, has advanced very rapidly in recent years by means of compressed air, electricity and ropes, that of gathering from rooms or working-places has remained almost stationary. Few large mines are without some method of mechanical haulage on main roads, but the gathering from working-places is still done almost entirely by means of animals or men. An effort to improve this has been made recently by the Consolidation Coal Company, under the direction of the writer, at its mines in the Georges Creek region. The seam worked is the Pittsburg bed, known locally as the " Big Vein." It is from 8 to 12 feet thick. Immediately overlying the coal there is from 5 to 6 feet of " rashings," consisting of thin alternating beds of shale and coal, which disintegrate rapidly on exposure to the air, and making a very treacherous roof. Rooms are driven from 12 to 15 ft. wide, with a single track close to one side. A line of posts is placed just far enough from this side to leave a clear space for the mine-car with a driver at the brake. This brings the post not far from the middle of the cross-bar, and provides more effectual support than if placed at the end. The tracks in these rooms are usually of 4 in. x 4 in. oak scantling, though of late years, owing to the advance in the price of lumber and the reduction in steel rails, more of the latter are being used. This track is laid by the miner. His pay for the work is included in the price per ton for mining. It is therefore, as a rule, unskillfully and often carelessly laid, and cannot be relied upon to carry safely any weight materially greater than the loaded mine-car. Compressed air was already in use on the main roads, driving motors weighing 30,000 pounds each, which were used to. bring the mine-cars that had been assembled from the rooms

Jan 1, 1904

By N. H. Emmons

THE work of a consulting engineer or manager, when controlling mining-operations, requires that he have all the information concerning the mine in as concise a form as possible, and as the ore-reserves and their depletion and enlargement are the vital points to be studied, it is well to have them kept up to date and in some convenient form. The present paper describes a method adopted by me, which shows in a very clear manner the ore-reserves in a mine. The case illustrated is that of a vein near enough to the vertical for the vertical elevation of the mine to be the main working-map. A flat ore-body would be represented on a similar plat, but instead of the horizontal thickness of the vein being shown in the circles, the vertical thickness would be inserted. Fig. 1 represents an ideal longitudinal elevation of a mine, plotted in the ordinary way, using 100-ft. blocks and section-lines. In a mine where the block-numbers are posted by the engineer underground, the system of keeping the ore-tonnages extracted from the different blocks is easily maintained, and the actual tonnages of ore extracted can be kept so that the surveyor can have a check on his estimate from time to time. The ore-reserve sheet, Fig. 2, should be the same size as the map it is to accompany. Each square is used for the description of the ore-reserve in the block it corresponds to on the elevation. Where the section-lines cross the levels a circle is drawn, in which are written the widths of ore at that point, these widths being used in the calculations of each block cornering in the circle. It has been found convenient to show the figures in black in the lower half of the circle when the actual widths of ore are known, and when it is necessary to make up the figures of probable ore, as at the time of making

Jun 1, 1912

By Howard Drullard

To OBTAIN the best results from hammer drills, close attention must be paid to two factors in drill maintenance, which are of equal importance; one is lubrication, the other is the shank. With the exception of stoping drills, most modern rock drills require both oil and grease. The oil ports are in the lubricator, on or behind the hammer cylinder; the grease port for the lubrication of the 'chuck sleeve and rotating mechanism is on the chuck end. Ordinary machine oil is not, adapted to rock drills; a heavier more gelatinous oil such as castor machine oil or liquid-grease should be used. The lubricators should be filled-once for every 12 or 14 ft. (3.5 to 4m.), of hole drilled. Grease-guns should be used to fill the port in the chuck end once a shift; a medium ( No. 3) grease is well adapted to this purpose. Hard grease must not be put into- the lubricators, as it will not flow through that part. Contrary to the popular belief, oiling a machine once or twice a shift does not provide sufficient lubrication; the drills should be oiled once for every 12 or 14 ft. of, hole drilled. The rotating handle of a stoping drill -is an oil reservoir and is provided with a port for oiling. The rotating handle is packed with wicking, or similar material, which causes the oil to feed slowly from the handle to the other parts of the machine. Stoping drills require oil at. least twice a shift; lighter oils than castor, such as Arctic Ammonia may be used.

Jan 8, 1920

By Charles H. Behre

SLATE (Thonschiefer, German; ardoise, French) is a rock, an aggregation of mineral grains, occurring in nature, which is used for roofing and other special purposes. It is finely granular and crystalline and generally derived from an originally clayey bed or series of beds. As a result of its having been put under essentially horizontal compression by geologic forces, this material now has its particles elongated and flattened so as to yield a very good rock cleavage along the flat surfaces of the minerals, a feature entirely independent of the original bedding in the rock. This is the gist of the definition adopted by the Committee on Slate of the American Society for Testing Materials. Slate differs in varying degrees from most other common rocks (such as limestone, sandstone, granite, and "trap") in chemical and mineral composition. Its most characteristic feature, however, is its tendency to fracture along a series of very nearly parallel and very closely spaced smooth planes, called cleavage planes. This property of cleaving, above all else, gives slate its industrial value. ORIGIN AND MODE OF OCCURRENCE Most of the features of slate might be anticipated from its origin. Being a rock rather than a mineral, its composition may vary consider- ably without impairment of value. In most slates, the material of which the rock is now composed was once deposited as clay on the bottom of a lake or sea. Subsequently these clayey strata were compressed by the kind of lateral pressure that folds rock strata, the minerals of the clay being changed or metamorphosed. In the chemical reaction involved, new and essentially plane-shaped minerals belonging to the mica groups were developed. Other minerals were formed but micas generally pre- dominated. These were oriented so that their two longer dimensions are approximately at right angles to the last effective direction of pressure. Since the crystals are thus subparallel, fractures can be developed easily along their surfaces, much as cards can be separated by inserting a knife blade between them. For the foregoing reasons, slate is found in noteworthy amounts

Jan 1, 1949

By L. R. Woodyatt, H. J. Beattie, C. T. Sims

Theories correlating the formation of u and related intermetallic compounds to the electron-per-atom density of binary and ternary alloys have appeared regularly in recent technical literature. These same principles can be modified and applied to complex precipitation-strengthened alloys such as the iron-, cobalt-, and nickel-base superalloys and the stainless steels. Since these complex alloys contain carbides and other phases that normally precipitate before the U-type phases, the nature and amount of the precipitated phases must be calculated first. The following general formula is then applied to the residual matrix composition of the alloy: element. The magnitude of the resulting number is indicative of whether the alloy will form a a -type phase. When these calculations (which are computerized) are systematically applied to alloys of knoun phase analysis, a breakoff in average electron-vacancy number is noted between U-free and U-prone alloys. Alloys with an average electron-vacancy number higher than the breakoff form a-type phases, while those with lower ones do not form these phases. This method could then be used to eliminate from consideration all experimental compositions that would precipitate undesirable phases. It also is useful in evaluating analyzed heats of alloys where minor heat-to-heat variations determine whether the alloy is o-free or o-prone. THE highly significant development of strong, ductile superalloys to provide reliable construction materials in the 1000" to 2500° F temperature range has been due principally to unremitting application of Edisonian techniques and logic by the dedicated physical metallurgists who have shouldered this responsibility. Tools such as the electron microscope, phase analysis, and computers to accomplish regression analyses have been used heavily, but the effort has been essentially practice of an art, rather than a science. The objective of this paper is to describe and illustrate application of some relatively fundamental principles to certain of these alloy systems in an attempt to remove some of the empiricism from the technology. Specifically, the work presented here deals with the use of periodic-group relationships to predict the formation of intermetallic phases which can occur in primarily austenitic (fcc) structures. Calculations that have been developed might be applied in the design of new alloys and the evaluation of known alloys, and thus have the potential of eliminating vast areas of unnecessary alloy preparation and evaluation. ALLOYING CONCEPTS AND STRUCTURAL FEATURES OF SUPERALLOYS Strength is produced in austenitic superalloys by three principle mechanisms: 1) precipitation of y'; 2) formation of carbides; 3) solid-solution hardening by soluble refractory metals. The first mechanism requires the addition of aluminum and titanium, the second requires carbon and carbide-forming elements, while the third calls for the addition of molybdenum and/or tungsten. A considerable concentration of chromium is usually maintained to resist oxidation/corrosion, but it is also an important carbide-forming element. Fig. 1 shows a sketch and electron micrograph of the structure of a typical wrought nickel-base super-

Jan 1, 1967

By J. Brian Eby

The Gulf Coast area of Louisiana enjoyed a particularly active and profitable year in 1939. Fifteen new producing structures were located and approximately sixty new producing sand horizons in old fields were opened in that period of time. The most important new discoveries are the Eola field, Avoyelles Parish, and the Paradis, St. Charles Parish. The Eola strike was indicated during December 1938, but the well was not placed on production until January 1939. Eola is particularly important because it was the first discovery of oil in a commercial quantity in the Wilcox formation in that area. Sid Richardson, of Ft. Worth, Texas, drilled the first well on the Haas Investment Company's property, which encountered the producing sand at a little below 8500 ft. Within the year 48 wells were drilled, 42 being commercial producers and 6 dry holes. The second most favorable discovery was the Paradis field, which was discovered by The Texas Company's Louisiana Land and Exploration Company's Paradis No. 1 well, in St. Charles Parish, just west of New Orleans. Detailed information concerning this field has not yet been made available but it is reported that the oil sand is as much as 175 ft. thick. The initial production indicated was 1750 bbl. daily and reports suggest a very large structure. In Calcasieu Parish the Humble Oil and Refining Company's Edge-wood Land No. 1 discovered gas in the Oligocene at a total depth of 7042 ft., in the Perkins area. Although two additional dry holes have been drilled in this prospect, it is still believed to have some merit. A new discovery is credited to Cameron Parish with the finding of Miocene oil in the Superior Oil Company's State No. 1 well in Grand Lake. The Chalkley field, Cameron Parish, is credited as a 1938 discovery but was largely developed in 1939 into one of the more important new fields. During the year 13 wells were drilled, 8 being oil wells and 5 dry holes. The oil is found in the Oligocene at depths of approximately 9000 feet.

Jan 1, 1940

By J. Brian Eby

The Gulf Coast area of Louisiana enjoyed a particularly active and profitable year in 1939. Fifteen new producing structures were located and approximately sixty new producing sand horizons in old fields were opened in that period of time. The most important new discoveries are the Eola field, Avoyelles Parish, and the Paradis, St. Charles Parish. The Eola strike was indicated during December 1938, but the well was not placed on production until January 1939. Eola is particularly important because it was the first discovery of oil in a commercial quantity in the Wilcox formation in that area. Sid Richardson, of Ft. Worth, Texas, drilled the first well on the Haas Investment Company's property, which encountered the producing sand at a little below 8500 ft. Within the year 48 wells were drilled, 42 being commercial producers and 6 dry holes. The second most favorable discovery was the Paradis field, which was discovered by The Texas Company's Louisiana Land and Exploration Company's Paradis No. 1 well, in St. Charles Parish, just west of New Orleans. Detailed information concerning this field has not yet been made available but it is reported that the oil sand is as much as 175 ft. thick. The initial production indicated was 1750 bbl. daily and reports suggest a very large structure. In Calcasieu Parish the Humble Oil and Refining Company's Edge-wood Land No. 1 discovered gas in the Oligocene at a total depth of 7042 ft., in the Perkins area. Although two additional dry holes have been drilled in this prospect, it is still believed to have some merit. A new discovery is credited to Cameron Parish with the finding of Miocene oil in the Superior Oil Company's State No. 1 well in Grand Lake. The Chalkley field, Cameron Parish, is credited as a 1938 discovery but was largely developed in 1939 into one of the more important new fields. During the year 13 wells were drilled, 8 being oil wells and 5 dry holes. The oil is found in the Oligocene at depths of approximately 9000 feet.

Jan 1, 1940

By G. T. Lineberry

Power requirements for a piece of mobile mining equipment are largely dependent on the set of conditions in which they must operate. These conditions are isolated and key parameters are identified. The effect of operating conditions on power determination is investigated. A simulation technique is developed to predict ranges of power demands for off-highway haul units as an archetype, permitting the analysis of changeable operating conditions. This program uses given data, conditions, and probabilities and ranges to solve for individual components of power, which can then be summed. By adopting such a technique, a systematic and rational determination of power is made possible. The usefulness of this basic approach in the determination of power requirements for other mobile mining equipment is emphasized.

Jan 1, 1983

By H. W. Johnson

DURING part of the year 1932, conditions at the plant of the Inland Steel Co. made possible the collection of data on two of the variables of blast-furnace operation, between which we observed an interesting correlation. The variation in percentage of coke ash in the coke seemed to be reflected in the variations in percentage of silicon and sulfur present in the iron. This subject is of particular interest during this period of low production because of its effect on quality and cost of pig iron. The consumers of pig iron are now more exacting in their requirements. Formerly 0.050 per cent sulfur was considered satisfactory; now many foundries and steel plants insist on iron under 0.030 per cent sulfur and expect it to average 0.025 per cent sulfur. To attempt to produce iron so low in sulfur and still have reasonably good furnace operation means that everything possible must be done to minimize all variations. This subject is also directly connected with the cost of producing iron. A blast furnace operates most economically and efficiently in rather narrow limits and so any variable that has range enough to disturb regular operation must be moderated. The importance of regularity is accepted and the methods followed to eliminate variations in materials such as coke and iron ore are recognized as indispensable. Uniformity of Ore and Variations in Coke Ash The delivering of uniform cargoes of well mixed ore to the blast furnace involves much handling and expense, but it is accepted that the trouble and expenditure are justified. After the ore reaches the dock, further mixing is assured by spreading ore in thin layers, preventing segregation by keeping piles level, variations in digging, and the use of several bins for one ore. And finally, the fact that the furnace burden generally contains three or more ores, together with several miscellaneous materials, eliminates the possibility of ill effects due to variations in any one. Thus, much effort is made to insure a uniform ore. But a variation in the percentage of silicon in ore is less detrimental than a variation in the percentage of ash in coke. The former affects

Jan 1, 1933

The Inspiration ore body was discovered in 1904, but a 50 -ton mill which was installed to treat the disseminated copper ore promptly failed. The original Inspiration Company then gave way to another, backed by W. B. Thompson, which found 40 million tons of ore. Control then passed to Anaconda and Dr. Louis Ricketts took charge as consulting engineer. He abandoned the mill which had been partially built (to the horror of the stockholders, according to Ira Joralemon) and spent a year and a million dollars experimenting with flotation. The first large copper flotation plant was then built and recovered 50% more copper than had previous gravity mills. It, of course, was highly successful and became the forerunner of modern flotation plants. Inspiration is distinctive as the first fully integrated copper operation in the United States. Three open pits supply sulfide ore to the concentrator and mixed oxide and sulfide ore to a vat leaching and electrowinning operation with leached ore also being sent to the concentrator. In addition, dump leaching supplies pregnant solution for scrap iron precipitation. Inspiration has recently constructed an electric furnace smelter and also operates a continuous casting and rod plant. The new primary 54 in. by 74 in. crusher was completed in May of 1972 and replaced an older unit which was in the way of the open pit development. It is of an unusual circular silo design, which permits dumping 0 from two positions at 90 from each other. One dumping position is in line with the spider, while the other one is at right angles to it. A box girder splitter bar hung from the dump pocket slopes downward from the second dump point, across the spider cap, and rests on the pocket bottom. This splitter was not installed to protect the spider but was to aid in distributing wet ore being dumped from that position to both sides of the spider. Any large amount of wet ore delivered to one side of the spider would pack in the crusher cavity. The round front wall of the 18 ft (5.5 m) deep pocket is unlined except for light steel protection at the top, while the straight back wall is lined with vertically positioned railroad rails. Water for dust suppression is sprayed into the pocket through a cluster of 3/8 in. (9.5 mm) nozzles at the back of the pocket. About 5 gpm (19 lpm) of water are mixed with 90 psi (620 kPa) air upstream of the nozzles to produce a fog which is effective in dust control. The 54 in. Allis -Chalmers gyratory is placed mostly within one quadrant of the circular enclosure to permit placement of the apron feeder on the lowest level in the proper position to transfer crushed ore to the

Jan 1, 1978

In the time it takes you to read this sentence, you'll be "zapped" by about 40 cosmic rays. Though harmless, their existence is being probed by a team of Texas A&M University physicists. What's most unusual about the research project is the design and location of the telescope required to detect the particles-it's made of fluorescent light tubes and is 457 m (1500 ft) underground at United Salt Corp.'s mine in Hockley, Texas, about 80 km (50 miles) southeast of Texas A&M's College Station campus. Cosmic rays are actually particles smaller than atoms traveling at extremely high speeds. Scientists believe their source is the same as that of starlight, and that these primary particles entering the earth's atmosphere create secondary particles in collisions with oxygen and nitrogen atoms.

Jan 6, 1978

By B. Egeberg

BRITANNIA metal is a white alloy consisting primarily of tin and antimony, the tin greatly predominating. The alloy usually contains a small amount of copper and occasionally very small amounts of one or two, other metals, such as bismuth, zinc, and lead. It is capable of being cold-rolled, it takes a high polish, and it is fairly noncorrosive; properties which make it a popular metal for many household and traveling utensils. Britannia metal is similar in many respects to pewter and has largely replaced pewter in the arts, but it should not be confused with that alloy, because pewter is essentially a tin-lead alloy, while Britannia is a tin-antimony alloy. In view of the fact that so little has been published concerning Britannia metal, the authors feel justified in presenting the results of their investigation, particularly since the behavior of this alloy under cold rolling and heat treatment differs so greatly from that of other metals and alloys. The old craftsman, engaged in the making of ornaments or tableware, heated the cold-rolled sheet metal or his finished product to a straw color corresponding to about 375° F., claiming to produce thereby a harder and more rigid article. The fact that possibly led him to this heating was that a reheated article or sheet made from Britannia metal has a distinct metallic ring when struck a sharp blow, whereas an unheated article or sheet has a leady, dead note. No doubt he has associated the metallic ring with a greater rigidity and strength, and justly so, as will be seen later.

Jan 1, 1928

By R. S. Dean

True careful work of Gross and Zimmerley1 has established the fact that the energy actually used in grinding is proportional to the new sur-face produced. This confirmation of Rittinger's law was made by crush-ing quartz in a frictionless drop-weight machine and determining the surface of the quartz by its rate of solution in hydrofluoric acid. The details of this procedure have been described adequately elsewhere and need not be repeated here. The resultant data furnish the only available basis for comparing accurately the efficiency of grinding machines. This method is so cumbersome experimentally that it has been little used. As an alternative all sorts of approximations have been proposed. The best of these is complete size analysis by sieving and elutria-tion. Such procedure is very lengthy and difficult to carry out accurately. Furthermore, any sizing method becomes very inaccurate for determining surface with very fine sizes where the ratio of surface to volume becomes very large. To avoid the lengthy and difficult technique of elutriation it has been proposed to estimate the size distribution below 200 mesh from various probability formulas. Such a procedure is at best an engi-neering approximation; at worst it is a mere guess. Some time ago Dr. V. H. Gottschalk2 found that the coercive forces of magnetite powders were directly proportional to the surface area, regard-less of size distribution. It was at once apparent that this furnished a method for determining grinding efficiency quickly and accurately. The only requirement was a single determination of the relation between the work input of the Gross-Zimmerley drop-weight machine and the coercive force of the resultant crushed magnetite.

Jan 1, 1936

By R. P. McLaughlin

IN most branches of the mining industry it is a well-recognized fact that care must be taken to protect the mineral deposit from undue physical injury. It is comparatively easy to grasp this idea when the mineral is a solid and the lives of workmen depend directly upon the care with which it is removed from its natural position, but when the product is a liquid. drawn up from pools several thousand feet beneath the surface of the ground through openings only a few inches in diameter, it requires some imagination to picture underground conditions and the changes which must often occur. The development of the petroleum deposits of California has been attended by numerous accidents, the results of which are readily noticed at the top of the wells and in the profit and loss accounts of the operators. Determination of the cause of these accidents has been the subject of considerable study, which naturally has fallen upon men familiar with technical methods. The greatest damage to the oil deposits of California has resulted from water finding its way into the oil-bearing sands, and it is the purpose of this paper to set forth briefly this phase of the oil industry. Much of the material here presented has previously appeared inn publications issued by the California State Mining Bureau, which, under the direction of State. Mineralogist Fletcher McN. Hamilton, has investigated the subject and taken steps toward improvement of conditions. The writer, having been in charge of this branch of the Bureau work, has gained considerable knowledge of existing conditions.

Jan 12, 1915

By W. C. Schafer

In tunneling or mining where hydraulic shields, moles, or rock boring equipment is used lasers such as those shown guide the production machine by providing a continuous and visible line and grade reference. In this application the laser may be mounted in the heading, preferably somewhere above spring line. If we view the circular heading as a compass in the vertical plane with 0º referencing at the crown of the heading and 180º on the invert, then it might be said that the laser may be mounted anywhere from 270º through 0º to 90º. The laser is generally mounted 2 to 3 ft off the wall or the crown of the heading by means of a bracket that may be attached directly to the liner plate. In cases where no liner plate is used, then brackets may be bolted directly into the ribs, or grouted directly into the rock. Once the laser is in position the beam is projected to the face. Two points must be surveyed upstream between the laser and the face which define line and grade. Targets may be suspended beneath each of these points approximately 2 to 3 ft. These targets may be circular or rectangular with a surface area which approximates 16 sq in. Each of these two targets should have a ½ to ¾ in. hole drilled directly in their center. When the laser is adjusted so that the beam passes through the holes in each of the two targets, the laser beam itself will parallel the center line of the tunnel and become a visible line and grade reference over the total beam projection.

Jan 1, 1970

By W. A. Bruce

This paper covers the theory and present state of development of an apparatus for the nonmathematical analysis of complex problems of reservoir and well behavior. At the present stage of development of this apparatus, it is capable of solving the water-drive problem of any reservoir performance for which a mathematical solution has been presented in the literature, either on the basis of steady or unsteady-state flow analysis. The theory is presented for the extension of the scope of this analyzer along the lines of the present development. The resulting apparatus should be able to solve reservoir-performance problems previously thought too difficult for practical solution by mathematical means. As an illustration of its operation and present scope, the analysis of a reservoir problem and synthesis of expected performance is presented. Introduction In this method† of analyzing problems of petroleum-reservoir and well behavior, the porous continuum of the reservoir is assumed to be divided into small blocks, or units. Each block is assumed to be small enough so that for a material balance on the fluids in the block an average pressure for the block can be used. In analyzing reservoir behavior from this point of view by mathematical means, a set of simultaneous difference equations would be obtained (two for each block), which must be solved or combined into a partial differential equation. In the method to be described here, instead of solving these sets of equations analytically, electrical units are constructed, which will behave in respect to the flow of electricity exactly as the reservoir units behave under various conditions of fluid flow. The electrical units are then wired together in the same way that the reservoir units are connected naturally by virtue of their geometrical locations and shapes. Fluid-Flow Equations Consider a block in a reservoir. Assume that reservoir fluid (or fluids) is flowing in at one face and out at the opposite face, and that the block is small enough so that at all points the stream lines are within one degree of perpendicular to the face. Furthermore, assume that the pressure, pi, at the upstream face (Fig, I) is not more than one per cent greater than P2 the pressure at the downstream face. A material balance will show that the mass of fluid flowing out less the mass of fluid flowing in will equal the change in density times the fluid volume. This is expressed in the equation:

Jan 1, 1943

By W. A. Bruce

This paper covers the theory and present state of development of an apparatus for the nonmathematical analysis of complex problems of reservoir and well behavior. At the present stage of development of this apparatus, it is capable of solving the water-drive problem of any reservoir performance for which a mathematical solution has been presented in the literature, either on the basis of steady or unsteady-state flow analysis. The theory is presented for the extension of the scope of this analyzer along the lines of the present development. The resulting apparatus should be able to solve reservoir-performance problems previously thought too difficult for practical solution by mathematical means. As an illustration of its operation and present scope, the analysis of a reservoir problem and synthesis of expected performance is presented. Introduction In this method† of analyzing problems of petroleum-reservoir and well behavior, the porous continuum of the reservoir is assumed to be divided into small blocks, or units. Each block is assumed to be small enough so that for a material balance on the fluids in the block an average pressure for the block can be used. In analyzing reservoir behavior from this point of view by mathematical means, a set of simultaneous difference equations would be obtained (two for each block), which must be solved or combined into a partial differential equation. In the method to be described here, instead of solving these sets of equations analytically, electrical units are constructed, which will behave in respect to the flow of electricity exactly as the reservoir units behave under various conditions of fluid flow. The electrical units are then wired together in the same way that the reservoir units are connected naturally by virtue of their geometrical locations and shapes. Fluid-Flow Equations Consider a block in a reservoir. Assume that reservoir fluid (or fluids) is flowing in at one face and out at the opposite face, and that the block is small enough so that at all points the stream lines are within one degree of perpendicular to the face. Furthermore, assume that the pressure, pi, at the upstream face (Fig, I) is not more than one per cent greater than P2 the pressure at the downstream face. A material balance will show that the mass of fluid flowing out less the mass of fluid flowing in will equal the change in density times the fluid volume. This is expressed in the equation:

Jan 1, 1943

By S. A. Braley

DRAINAGE water from coal mines is probably the most serious water pollution problem today, varying in importance according to location of the mines and geological structure. Drainage may be either acid or alkaline in character. Acid discharge, the most severely detrimental to a stream, is caused by natural oxidation of the sulfuritic material (FeS2) in the strata associated with the coal seam. Since the acid is the result of a natural reaction the acid water differs because it does not cease with abandonment of the mining operations. There is no known economical method of neutralizing acid mine water or any practical method to prevent oxidation of exposed pyrite. Since production of acid from a mine does not stop when mining stops, the total quantity produced depends entirely upon the excavated areas. The increasing volume of acid water in many mines has greatly increased operating costs. Pumping is expensive and acid mine waters are destructive of all equipment, especially metals in pumps and piping, and necessitate the use of corrosion-resistant materials. Discharge of the acid mine drainage into streams neutralizes their normal alkalinity, causes them to become acid, and produces an environment unfavorable for aquatic life and unsuited for industrial or domestic use without costly treatment.

Jan 1, 1957

By C. R. McClure

The objective of this papef is to summarize briefly the practical use of rock mechanics in design and construction of various types of structures. These range from foundation for industrial facilities, nuclear power plants, bridges and dams to tunnels and underground caverns. The use of rock mechanics has varied from performing a few laboratory unconfined compressive tests on core samples to complete field and laboratory tests for underground power caverns. The primary difference between the rock mechanics studies we hare for construction projects and those most commonly found in the literature is that our tests must provide immediate answers to specific questions facing a design or construction engineer. For example, when we make a plate-bearing test we arrive at a load-deformation relationship. We realize that this is not a true modulus of elasticity. Yet, when considering the resistance the rock will provide against forces occurring in a pressure tunnel it is a far more useful value than the true modulus of elasticity of the rock. Another example of this difference in interest is in the use of flat jacks. Many people criticize the use of flat jacks because they measure the stresses in the disturbed zone very near the surface and do not represent the undisturbed stress condition in the rock. However, in actual construction it is frequently those near-surface stresses with which we must cope. We are interested in both the stress conditions present prior to excavation and those as modified by construction of an exploratory adit or drift. Fundamentally, we are interested in the practical application of rock mechanics in the solution of problems of design and construction of civil engineering works.

Jan 1, 1968

By Dan A. Permenter

This paper assesses some of the critical factors that must be considered and addressed in the implementation of small computer systems for technical applications within a coal company. Aspects of hardware selection that are somewhat specific to the coal industry are discussed, and a table of potential areas of application is presented. The dilemma of internal software development is presented and a software development program based on a users group approach is outlined and discussed in detail.

Jan 1, 1983