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By Norman Maxwell

There was more activity in crude production in northwestern Pennsylvania in 1935 than for several years before, resulting in an increased oil production and also in the number of wells completed. Crude -production approximated 16 million barrels for the state, an increase of about one million barrels over 1934. Demand, indicated by refiners' runs to stills, increased proportionally, leaving stocks of available crude at the end of the year at the lowest point since the middle of 1934, when they reached an all-time low. The price of crude varied during the year from a low of $2.02 to a high of $2.27 at the end of the year for Middle district oil. The price of Bradford and southwest Pcnnsylvania oil changed accordingly. The average for the year would be a lower price than in 1934. A summary of the production data for the year 1935 is given in Table 1. In making up this table, 1935 figures were simply added to the table published by S. H. Cathcart last year1. A list of important wildcats is given in Table 2. Bradford Field Approximately 10,000 acres of the proven producing area of the Bradford field is in Cattaraugus County, New York, and it is possible, by differences, to distinguish the Pennsylvania production from the New York portion. The listed production for the Bradford field includes only that portion of the field situated in Pennsylvania, but also includes production from a small pool, locally known as the Mt. Jewett-Kanesholm pool, where the Bradford sand is being developed and flooded in precisply the same manner as that of the Bradford field itself. The Mt. Jewett-Kanesholm pool is not, strictly speaking, an extension of the Bradford field, but inasmuch as it is so closely allied with the Bradford field-—that is, the sand is the same and the production methods are the same—the production and drilling figures include this area.

Jan 1, 1936

Productivity of mines can be improved by taking fewer, but larger blasts. The initial blasts taken in starting a mining block are restricted by the low amount of void or space to fire into. Block cave mines are using a blasting technique to blast areas that have less than the normally accepted minimum void to establish drawbells for their orebody development. This technique used in block caving mines can be used to improve productivity in mining operations that utilise other mining methods. Some larger blasts have been done in mines, using open stoping methods, which have had void ratios as low as 13 per cent. This has been possible with the use of the explosive gases to transport the broken rock out of the area normally considered to be available to blasts. This trapping of the explosive gases in the broken rock has allowed rock to be moved over 30 m, horizontally, to allow for more void to be available in the blast area. This gives the necessary void ratio allowable to fire larger blasts. This paper will discuss the blasts where this technique has been used in mines to increase the tonnes fired in low void situations. It will also discuss where this type of blasting may improve the productivity of underground mines. Figure 1 shows the how explosive gases have enabled the broken rock to flow out of a draw point without the typical air blast and fly rock that would normally cause a rope suspended sign to be damaged beyond use.

Jan 1, 2008

By P. C. Benedict

"The Island Mountain mine is at the southeast end of Island mountain; across Jack of Clubs lake from the Cariboo Gold Quartz mine.; The orebodies consist of quartz veins and pyritic replacement deposits in limestone. To December 31; 1944; there has been mined 296; 273 tons of quartz-vein ore averaging about 0.34 oz. gold a ton; and 101; 002 tons of sulphide ore averaging about 0.83 oz. gold a ton; a total of 397; 275 tons averaging 0.46 oz. From this; 175; 985 fine oz. of gold and about 26; 450 fine oz. of silver were recovered; having a value of $6; 510; 521.More than 95 per cent of the production has come from a band 500 feet wide along the contact of the Rainbow and overlying Baker members and extending about 100 feet into the latter. Evidence that the Rainbow belongs stratigraphically above the Baker is presented later in this paper. Both members are most variable lithologically, and individual beds and whole series of beds pinch out in short distances. In part, at least, this is due to squeezing out incidentally to intense folding. No section can be claimed with assurance to be really representative. However, both memb.ers are composed predominantly of quartzitic rocks. Both contain argillaceous quartzite, argillite, limy quartzite, limy argillite, limestone (marble), and minor amounts of highly ankeritized rocks believed to be igneous sills possibly originally approaching diorite in composition."

Jan 1, 1954

By Virgínia Morete Barbosa Bertolo

Ligas a base de zircônio são utilizadas na indústria nuclear devido à baixa absorção de nêutrons e alta resistência à corrosão em ambientes de alta temperatura e pressão. Nas condições de operação essas ligas estão sujeitas à fragilização pelo hidrogênio. Este trabalho visa avaliar o efeito do hidrogênio na liga ZirBrasil-1, produzida em forno elétrico a arco VAR (Vacuum Arc Remelting) nas condições: encruada e tratada termicamente. As análises de difração de raios-X indicam a existência de uma matriz Zr-a, hexagonal compacto, para todas as condições de tratamentos térmicos. Após a hidrogenação, ocorreu a formação de ZrH e ZrH2. Os hidretos formados são de pequeno volume e não conectados para as amostras laminada e tratada a 700°C/1 h e 800°C/2 h, sendo que a condição de 800°C por 6 h obteve a maior quantidade de hidretos por área e alguns hidretos conectados. Em todas as condições os hidretos se encontram espaçados ao longo da espessura das amostras. Os resultados de microdureza Vickers indicam a ocorrência de precipitação para tratamentos a 800°C e confirmam o efeito fragilizador do hidrogênio. A liga encruada absorve maior quantidade de hidrogênio, com início do processo de absorção ocorrendo após 12 horas, já a amostra tratada a 800°C por 6 h absorveu apenas 0,5%H e iniciou a absorção após 26 h. O conjunto de resultados permite concluir que a amostra recristalizada é a indicada para o desenvolvimento do processamento termomecânico, quando comparada a condição encruada devido ao maior tempo para início do processo de absorção e menor quantidade absorvida de hidrogênio.

Aug 8, 2018

By John W. Frey

This paper presents one of a series of digests of foreign mining legisla- tion and court decisions which is being prepared in advance of a general report relative to the rights of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws of Trinidad has been prepared from the best information available in ashington but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State.

Sep 1, 1930

By L. G. Austin

INTRODUCTION Autogenous (including semi-autogenous) grinding has probably been the most important single innovation in milling practice for the last twenty years. However, the design of these units has been largely a matter of trial-and-error, since the normal empirical laws for the design of ball mill circuits do not apply with exactitude to autogenous grinding circuits. There have been examples of autogenous mills failing to achieve output or product specifications. It is worthwhile, therefore, to attempt to develop a more detailed and precise set of design laws, using the concepts of specific rates of breakages and daughter fragment distributions (1), and performing mill simulations by computer. This type of approach has been applied to ball and rod milling (2, 3,4,5), but even for these mills it is by no means complete as yet (6), because of the amount of experimental work involved. There has not been a strong incentive for industry to develop new design procedures in ball and rod milling because the prior back-log of experience with these mills makes for easy design by empirical comparsion with existing systems. The new approach has been followed mainly by University groups (7,8,9,10), although experience in Australia (9,11) has shown the advantages of the approach. Stanley (12) has applied the approach to results from a large autogenous mill, and we will use many similar concepts to his work, but extend the concepts to a more

Jan 1, 1977

By M. J. Brevoort

Research work in the Bureau of Mines cryogenic laboratory requires the use of high-sensitivity galvanometers of the d'Arsonval type in a building that is subject to unusually severe vibrations. A modified form of the galvanometer suspension described by Julius' has damped the vibrations so successfully that a short note concerning it is thought to be desirable. The laboratory is on the site of the Amarillo helium plant near a building that houses gas engines of from 180 to 250 hp driving compressors and electric generators. The distances from the galvanometers to the individual engines range from about 80 to 180 feet. The subsoil, consisting of black clay loam, transmits the impulses without much damping. The usual methods of protecting galvanometers from vibration were tried and proved fruitless. A Julius suspension purchased on the market was carefully installed in the hope that it would overcome the difficulty, but the conditions were too severe even for this elaborate arrangement. Several modifications of the original Julius suspension, which were then introduced, resulted in almost complete elimination of all vibrational effects. These modifications were suggested by careful study of the original idea embraced in the Julius construction. They were designed to give further constraint to motion in any direction other than that parallel to a line from the point of support through the center of gravity of the suspension, This was accomplished by making the suspended frame more rigid and by improving the means of adjusting each of the supporting wires to the same degree, thereby transmitting any impulse symmetrically through the three wires. The result was a suspension that is more effective, particularly for severe vibration, than the form described by Julius; also, it is believed to have advantages in stability, simplicity, and ease of adjustment over the few suspensions for this type of service that the author has found described in the literature.

Jan 1, 1931

By R. Wang

"Under high stress conditions, rock bursts, borehole breakouts, and spalling events are common phenomena that occur around underground openings. In general, together these three phenomena represent brittle failures of an intact rock mass; however, individually they reflect different failure modes under high stresses. After analyzing and comparing the stress-to-strength criteria for rock bursts, borehole breakouts, and spalling events, proposed by previous researchers, it is found that these brittle failure phenomena share common stress-to-strength prerequisite. The stress-to-strength preconditions for brittle failures can be defined by the ratio of the maximum tangential stress around an underground opening to the uniaxial compressive strength (UCS) (s?max/sci) or by the ratio of the maximum far-field principal stress to the UCS (s1/sci). Both these indicators can be used to reflect the same stress preconditions. For s?max/sci, a ratio of 0.4±0.1 represents the critical stress requirement for brittle fracture. However, for s1/sci, a ratio of 0.15±0.05 should be considered as the critical stress requirement. Numerous engineering case studies and analysis of rock mechanics based on the Hoek-Brown criterion also verify these two stress-to-strength preconditions. Here, these two indicators are presented with an error range because complex rock mass quality ratings, lithology, and geotechnical conditions have profound impacts on the stress-to-strength preconditions for brittle failures. INTRODUCTIONHigh stresses are one of the most important factors that must be considered when undertaking underground rock mass projects (Kaiser et al., 1998). Wang et al. (2009) reviewed current progress in the evaluation of high stresses and their corresponding criteria. However, after clarifying the definition of high stress, civil engineers need to understand the deformation and failure behaviors of rock mass around an opening under high stresses. Under high stress conditions, the deformation of rock masses around an opening can be categorized into two groups, i.e., severe brittle failures (or rock bursts) and compressional plastic deformation of the surrounding rock mass, as indicated in Figure 1."

Jan 1, 2015

By E. Stamboliadis

Gravity separation techniques were used in the early years to extract native metal nuggets and flakes from placer gold deposits. This was relatively easy for visible metal grains. As the size of the grain becomes smaller traditional gravity separation techniques become inadequate to recover native gold. Cyanidation was invented as a solution to the problem. According to it, gold and other precious metals are dissolved in water by sodium cyanide. The result was a drastic increase of world gold production but at the same time environmental issues were raised. In Greece gold mining has become equivalent with the absolute destruction of the environment and is under extinction. In the last years a new type of gravity equipment have been produced which create a gravitational field up to 200 G and can separate gold from gangue minerals at sizes below 50 µm. The strong gravitational field is created by centrifugal forces and the separation occurs in a fluidized bed, formed by water flow. Accumulations of finely disseminated native gold are found in the sedimentary sequence of the Flysch of the Ionian Zone. The main gold minerals are gold and electrum present as free metal flakes and micro nuggets in the size range between 5-250 µm. Test work, using the Falcon SB40 centrifugal concentrator, at the Department of Mineral Resources Engineering at the Technical University of Crete, has shown that this particular type of gold ore can be processed by gravitational methods that require no reagents and are environmentally safe.

Jan 1, 2003

By M. E. C. Snyman, N. Naudé

"Coal fines produced during processing are difficult to dewater and result in a lower quality product and consequent lower value. A South African coal mine experiences severe difficulties with belt filter dewatering operations due to the presence of fines reporting from the thickener underflows. Plant 2 currently handles super-fine particles of size -34 µm and has low belt filter efficiency: excessive moisture retention lowers the product quality and strains downstream processing. It was necessary to determine an alternative method for dewatering these fines. Blending of fine material with coarser material was proposed as a solution. The effect of coal particle size and layering during ultrafines belt filter dewatering was evaluated using various blends of the fine Plant 2 material with coarser Plant 1 material. The best layering arrangement of the two materials and its optimum blend required to achieve reduced filter cake moisture content was determined in practise using a vacuum filter to simulate belt filtration. A blend of the two materials gave improved dewatering efficiency for the belt filters compared with that of the Plant 2 material alone. The best layering configuration was with Plant 2 material at the bottom and Plant 1 material on top. The optimum blend for industrial applications comprised 48% fines from Plant 2. IntroductionFines are produced during the processing of coal. It is estimated that 2 to 3% of run-ofmine coal reports to the ultrafine portion (-100 µm) (le Roux, 2005). The particle size of coal is inversely proportional to the amount of water adsorption, so smaller particles adsorb more moisture. Moisture removal requires either mechanical processes or thermal drying: mechanical processes are less expensive, but the fines still have high moisture retention. Discarding of fines leads to economic losses, so it is essential that they be dewatered so that they can then be sold as a product: fines need to be treated for both resource management and conservation reasons (Kenney, 1994). Removal of free surface moisture from ultrafine coal particles using a belt filter therefore remains a process that needs to be continuously improved. Ultrafine coal originating from a thickener underflow is known to be difficult to dewater owing to factors such as filter cloth blockage and moisture retention due to clogging. Mixing of finer and coarser materials has been proposed to deliver better dewatering efficiency and improved the quality of the recycled water (Kenney, 1994)."

Mar 1, 2019

Geologists in some underground gold mines collect grab samples from broken ore piles or trucks as a method of grade control. It is often known as muck sampling. Generally, the goal of grab sampling is to try and reconcile the mined grade at the ore source to the predicted grade and/or predict the mill feed grade. The mass of the sample collected is limited by health and safety issues, as well as the capacity of the laboratory to process the samples within a given timeframe. In general terms, grab sampling is known to be problematic because samplers tend to over sample the fines, and/or pick out high-grade fragments; surface sampling of piles does not test material within the pile; muck piles in development drives/faces are likely to be zoned due to the blasting sequence; high or low-grade material may preferentially segregate in the pile during mucking; the five percent mass reject size of the material in muck piles is very large from underground blasting; some correlation usually exists whereby the larger fragments are enriched or depleted in the critical component of value; and the average error made in estimating the true stockpile grade is likely to be high. The method is prone to chronic fundamental sampling, grouping and segregation, delimitation, and extraction errors. Substantial warnings must be given with respect to the use of grab sampling for grade control in gold mines. The method may appear to work sometimes, which can be attributed to a fine gold particle sizing and more disseminated distribution. As with all sampling methods, its appropriateness must be determined by ore characterization and heterogeneity testing to ensure the method suits the ore type.

Jan 1, 2009

MRS. SIDNEY J. JENNINGS, President, MRS. ARTHUR S.. DWIGHT, First Vice-President, MRS. KARL EILERS, Second Vice-President, MRS. H. W. HARDINGE, Third Vice-President, MRS. BRADLEY STOUGHTON, Recording Secretary, MRS. AXEL 0. IHLSENG, Corresponding Secretary, MRS. ARTHUR S. DWIGHT, Acting Treasurer. Welfare Committee MRS. C. C. BURGER, Chairman, Sub-Committees Americanization Belgian Relief MRS. LEVI HOLBROOK, Chairman, MRS. HENRY H: KNOX, Chairman, Emergency MRS. HERMAN A. PROSSER, Chairman. Since the annual meeting held in February, 1917, when the Woman's Auxiliary to the A. I. M. E., was formed, the work of organization, which of necessity must be slow, has steadily gone forward. Under the Chairmanship of Mrs. C. C. Burger of the Welfare Committee, three active sub-committees have been formed: that of Americanization; under Mrs. Levi Holbrook, who is eminently fitted for such a position, by her active and valuable work in a number of the fine patriotic societies of our country; the Belgian Relief Committee, under Mrs. Henry H. Knox, which has clone phenomenal work in the three months of its existence, and whose report is later given in detail; and the Emergency Committee under Mrs. Herman A. Prosser, which has a fund already established, and is. in close touch with Major Arthur S. Dwight, ready to act when necessity arises. The officers of the Auxiliary feel more than gratified at the response so far received, and in a later issue will print extracts from letters, if permission can be gotten from the writers, showing the interest and enthusiasm that have beer aroused by the formation of a Woman's Auxiliary. Answers have even come from far Korea "the hermit nation," from Australia, from South America, showing what a bond of sympathy and, helpfulness is in process of growth. It is our sad duty to announce the death of our Treasurer, Mrs. George D. Baryon, who, from the very inception of our plan to organize, was an inspiring and valuable co-worker. Her place will be difficult to fill. Mrs. Arthur S. Dwight is Acting Treasurer at present. The Auxiliary wishes to express its heartiest thanks to Mr. Stoughton, the genial and efficient Secretary of the A. I. M. E., for his cooperation and valuable suggestions in the difficult work of organizing. He has indeed been "a guide, philosopher and friend." SUSANNE M. IHLSENG (MRS. AXEL 0.), Corresponding Secretary.

Jan 7, 1917

By David Oyler

Unusual circumstances may require that a longwall retreat into or through a previously driven room. The operation can be completed successfully, but there have been a number of spectacular failures which exposed miners to serious roof fall hazards. To help determine what factors contribute to such failures, the National Institute for Occupational Safety and Health (NIOSH) compiled a comprehensive international database of 130 case histories. The cases include five failures where major rock falls occurred in front of the shields, and six even more serious failures involving major overburden weighting. This suggests two room failure mechanisms. The first is a roof fall type failure caused by loading of the immediate roof at the face as the fender narrows. The second is a weighting type failure caused by the inability of the roof to bridge the recovery room and face area, and affecting rock well above the immediate roof. The data indicate that the roof fall type of failure is less likely when intensive roof reinforcement (bolts, cables, and trusses) is employed together with higher-capacity shields. The overburden weighting failures, in contrast, occurred when the roof was weak and little standing support was used.

Jan 1, 1998

By Seymour Wasserman

To develop noise control designs for secondary crushers in Taconite plants. Taken into consideration: 1. Acoustical criteria 2. Day-to-day operational considerations and maintenance accessibility 3. Materials of construction 4. Adaptability of design to other Taconite plants having crushers 5. Cost of noise control treatment.

Jan 1, 1977

By Aldo Henrique de Almeida Barbosa

Dentre os revestimentos galvanizados a quente, o galvannealed (GA) destaca-se por possuir uma estrutura composta por fases Fe-Zn, o que lhe confere excelente desempenho na aplicação em peças de alta solicitação. A qualidade do revestimento GA é governada principalmente pelo tratamento de galvanneling, tendo em vista seu efeito na formação dos compostos Fe-Zn. A influência desse tratamento é ainda mais pronunciada em aços com características de bake hardenability (BH), pela presença de elementos que alteram a sua reatividade. Nesse estudo, foram avaliados os efeitos das condições de galvannealing na formação do revestimento GA sobre aços BH. Para tal, ciclos de galvannealing variando-se a temperatura de aquecimento entre 530°C e 580°C foram simulados em escala de laboratório. Além dos ciclos completos, foram também realizadas interrupções do tratamento ao longo da etapa de encharque, através de resfriamentos bruscos das amostras, com o objetivo de avaliar a microestrutura do revestimento ao longo de todo o tratamento. Os resultados permitiram determinar os mecanismos de formação e crescimento dos compostos intermetálicos Fe-Zn que constituem o revestimento galvannealed, e correlacioná-los com as características do produto final, de maneira a estabelecer faixas adequadas de processamento desse material.

Jul 30, 2018

By R. L. Slobod, B. H. Caudle

In the past, the main emphasis in attacking the problem of the recovery of oil has been on the determination of fluid flow characteristics and residual oil saturation in the part of the reservoir which is contacted by a displacing phase. It is recognized that the determination of the fraction of the reservoir contacted in secondary recovery operations is also of great importance in predicting the ultimate recovery to be expected. A method is described in which radiographic techniques are used to determine these areal sweepout factors for any type of well spacing. Data showing the relationship of viscosity ratio and relative permeability to areal sweepout efficiency are presented for the five spot and the direct line drive well spacing patterns. Further applications of the method to studies of the displacement efficiency in the area contacted are mentioned. INTRODUCTION The problem of increasing oil recovery from typical reservoirs is generally attacked by trying to devise some means for reducing the residual oil in that part of the reservoir which is contacted. The fraction of the reservoir contacted in the displacement process. however, is also of major importance but has been given less consideration in the past. one reason for this neglect is the meager information available on the portion of the reservoir contacted and the magnitude of changes in this factor as operating conditions are varied. Until recently, the only means available for determining this quantity has involved the use of the electrolytic or poten-tiometric modelsl in which one is limited to working with a mobility ratio of unity. while means for calculating the volume of a reservoir contacted do exist. the calculations are very tedious for systems with mobility ratio different from unity. Recently several such determinations have been reported,213 and an experimental method involving a step-wise use of potentiometric models has been described.' A new method which has been developed for studying the areal distribution of phases in a porous medium is discussed below. This tool can be' used to determine the effect of operating variables such as viscosity, relative permeability, presence of gas, mobility ratio, rate and stratification on the fraction of the reservoir contacted by the displacing medium. This development based on the use of X-rays gives a pictorial representation of the location of the phases. Further, the amount of each phase at each point of interest can be determined quantitatively. X-RAY METHOD FOR AREAL STUDIES In this method the location of various phases distributed Over a test area are observed simultaneously by obtaining a photographic record of the transmission of X-rays through the test plate. This procedure is an adaptation of the radiographic techniques which have 10% been used in the medical and industrial fields. Just as the medical profession uses a chest plate to show spatial interrelationships, the location of an X-ray absorbing fluid and a nonabsorbing fluid in a porous medium can be determined by obtaining a photographic record of transmitted X-rays. Moreover, as changes occur in such a System, these changes can be observed by taking successive photographs. Previously, X-ray methods have been used in fluid flow studies to determine quantitatively the saturation at a given point in the system. The intensity of the transmitted X-rays was measured by an ionization chamber, so that a point by point survey of saturation could be made. In comparison with this earlier quantitative procedure, the photographic procedure which simultaneously observes the saturation at many

Jan 1, 1952

By Richard Hodgson

FMC Corporation, at their mine and soda ash refinery near Green River, Wyoming, currently mines in excess of 3 million tons per year of trona. Upon completion of the current expansion, the mine will be producing in excess of 4.0 million tons per year. The single level mine, approximately 1,500 feet in depth, is currently serviced by five (5) concrete lined circular shafts varying in diameter from 12 ft. to 24 ft. A sixth shaft is complete, but not yet operational and the seventh is currently being sunk. Two of the shafts are equipped with single drum hoists. The original production shaft is equipped with a double drum hoist. The newest production shaft and the main service shaft are both equipped with ground mounted friction hoists. These friction hoists have given excellent service and another will soon be installed as a man and material hoist at No. 7 Shaft. There are a number of advantages that the ground mounted hoist has over a tower mounted hoist. There are also operating problems common to both. FMC's original experience with ground mounted friction hoists began in 1962 with the conversion of a single drum hoist to a friction hoist. The converted hoist was an Ottumwa with a 5 ft. diameter drum and a 4 ft. face. This hoist had been installed at the No. 3 Shaft for some years prior to its conversion to a friction hoist. At the time the conversion of this hoist was made, there were no friction hoists in service in Wyoming. Wyoming mining laws required that all conveyances carrying men be equipped with safety dogs. Since it was desired that wire rope guides be used, safety dogs were impractical. Agreement was reached with the State Mine Inspectors that safety dogs would not be necessary provided that recommended rope safety factors for hoisting men would still be maintained if one hoisting rope was broken. Since-the shaft is approximately 1,500 ft. deep, the recommended safety factor is 6.0 so that this installation has a safety factor in excess of 8.0 for hoisting men when new ropes have been installed. The hoist conversion was engineered by Lake Shore, Incorporated. The friction ring was made in halves and bolted over the original drum face which had been machined to remove the grooves. The ring provided for four 3/4 in. diameter ropes on 8 inch center to center spacing. The pitch diameter of the modified drum was 72 inches. The grove liners are hald in place by hard-wood wedges bolted to the drum. The other modification required by the conversion was an increase in size of bearing caps and the hold-down bolts because of the increased force tending to lift the drum.

Jan 1, 1975

By E. J. Ripling

TUBES may be produced by a large number of forming processes, the most common of which will be discussed analytically in this paper. In no case will the stress analysis for any given tube producing process be derived formally for where such analyses are available, they may be referred to readily. Rather, emphasis will be placed on the interpretation of the theory of the different processes, few of which are developed to a state that will allow rigorous mathematical analyses, in an attempt to give a rational description of the effects of the different variables involved in each method. Tube producing methods can be divided into two groups: Those used to form shells, and those used to further work these shells into a shape more suitable for their final use. Among the first group are included roll piercing, extrusion and cupping for seamless shells, and bending with welding for welded tubes. The re-forming processes include sinking, drawing with a plug, and drawing with a rod. Only the plastic forming operations will be discussed here; other forming processes such as casting shells will not be considered. PRODUCTION OF SHELLS Shells for Seamless Tubing Piercing: The extremely important process of forming an axial hole in a billet by oblique rolling never has been analyzed satisfactorily, although a certain amount of experimental work relating to this process has been conducted. There are a number of factors that make piercing difficult to analyze; one of these is the fact that piercing is not a problem in plasticity, but one in fracturing, and the laws of fracturing are even less well understood than those of plasticity. If, however, it is assumed that fracturing occurs on a surface as a result of tensile stresses acting normal to this surface, piercing can be analyzed qualitatively by examining the stresses established in the oblique rolling process. To determine the origin of the tensile stresses that are thought to effect piercing, it will be necessary to know the angular relationships between the maximum stresses that are established in piercing. These angles quite frequently can be determined in a plastic deformation process by an examination of the deformed product. For example, consider the stresses established when a tensile test is conducted on a rectangular cross-sectional specimen of pearlitic steel. When stretched, this material first flows plastically, exhibiting the well-known yield jog on a stress-strain curve. The formation of the slip areas that give rise to the yield jog can be detected during the straining, since these flowed areas cause depressions on the specimen surfaces which can be seen if the surfaces are polished highly. The plastically strained areas also can be found after the specimen has been stretched to a strain not exceeding the yield jog, by sectioning the test piece and. etching these sections with Fry's etch. With this etchant, it is possible to dis-

Jan 1, 1951

By Thomas M. Chance

All gravity methods for the separation of ore from gangue, or of slate and other refuse from coal, are based upon differences in the falling velocities, in some fluid medium such as air or water, of the materials to be separated. As all materials falling in a vacuum have the same velocity, independent of the size, shape, weight or specific gravity of their individual particles, it would be more accurate to describe the operation of these methods as depending upon the retardation of falling velocities effected by the resistance of a fluid medium, this retardation being greater for small or light particles than for large or heavy particles. This generalization is true also of those appliances utilizing centrifugal force to replace or to supplement the action of gravity. The separation of materials of different specific gravities by means of a fluid having a specific gravity greater than that of the lighter particles and less than that of the heavier particles has not been applied commercially, or on a large scale, to the separation of ores or to the washing of coal, the method being limited to laboratory experimental work or to laboratory determinations for the purpose of checking up the work of jigs, classifiers, and other types of concentrating appliances. A solution of zinc chloride has thus come into general use in the laboratory to separate coal, bony coal, and slate, both to check up the work of coal-washing plants and for the purpose of making tests preliminary to the designing of coal-washing plants. The use of a heavy solution of some chemical in water has often been proposed for making such separations, especially in connection with the washing or preparation of coal. Practically insuperable difficulties, however, have prevented the commercial development of any such process, the difficulties being both physical and financial. The cost of the chemical used to make high-gravity solutions is usually prohibitive, and the freeing of the coal from all traces of the chemical is found to be practically impossible. Such solutions inevitably penetrate the individual lumps and particles of coal, transfusing into the pores and saturating the joint-planes, and very large quantities of wash water

Jan 1, 1918

The underwater test method for the determination of energy content of explosives is a very useful method. It’s also the only one which can separate shock and gas heave energies from each other. The total energy can be determined as a sum of these partial energies. Because of this special feature, the test method can be used to develop the energy content of explosives for different purposes; the military high explosives should contain more shock energy whereas the gas heave energy is a very important feature for the blasting explosives. The goal of this study was to find out the effects of aluminium and sodium perchlorate increments to the shock, gas heave and total energy values of an emulsion explosive and detect the particle size effects of two different aluminium powders to the total and partial energies as well. Both partial energies as well as the total energy were observed to increase linearly as a function of aluminium (A-80) concentration. The fine aluminium powder (A-100) (6%) also seemed to increase the shock energy of the explosive slightly whereas the gas heave energy was observed to remain unchanged to compared to the normally aluminazed (A-80) (6%) emulsion explosive. Therefore the fine aluminium powder also increased the total energy, but only very silightly. The fine aluminium powder can probably take apart to the chemical reactions more easily during the detonation. (3%) of sodium perchlorate (NaClO4) mixed with (6%) of (A-80) aluminium powdered emulsion explosive was observed to effect to the gas heave energy content of the explosive, but only very slightly. The shock energy was observed to remain unchanged.

Jan 1, 2005