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AARONS, J. BOYD; Major. AGNEW, FRANK VANS. ALLEN, HERMAN H., Private, D Co., 8th Reserve Engineers. AMBLER, HARRY A., Second Training Camp,, Ft. Sheridan, Ill. BAINS, THOMAS M., JR., Major, Engineer Officers' Reserve Corps. BANKS, H. R., Lieutenant, Canadian Engineers, B. E. F. BARBOUR, PERCY E., Deputy' Supt. (Captain), New York State Troopers; Captain, 22d Regiment, N. Y. N. G. BARLING, H. B., 1st Lieutenant, Engineer Officers' Reserve Corps. BARRETT, LESLIE P., Lieutenant, A. E. F., France. (Unattached.) BENSEL, J. A., Major, Engineers' Reserve Corps. BIGELOW, BRAXTON, Royal Engineers, B. E. F. BLOOMFIELD, E. C., Lieutenant. BORROW, F. K. BOWLES, MARTIN F., 2d Lieutenant of Infantry, Camp Funston, Kans.

Jan 11, 1917

By R. E. Collom

VARIOUS chapters already written in the history of development of the North Dome of Kettleman Hills are monotonously identical in the one underlying theme of conservation of oil and gas. Discovered on Oct. 4, 1928, by Milham Exploration Co. with its wildcat Elliot No. 1, the field has been subjected to practically every modern form of produc-tion restraint in the name of conservation. The record thus far developed shows that conservation was had for a time, at a price; and that unitiza-tion must he blessed by single ownership or 100 per cent participation to be effective. In fact, incomplete unitization places a heavy handicap upon its participants in the competitive development that follows.

Jan 1, 1937

Estimated Receipts Dues Arrears $ 3,500 00 Current 108,115 00 New Members - 11,937 00 In Advance 1,763 00 $125,315 00 Initiation Fees - 7,250 00 Initiation Fees-Additional if increased to $20 00 7,250 00 Sale of Transactions 3,000 00 Sale of Binding 7,092 00 Sale of Magazine 2,913 00 Sale of Pamphlets 370 00 Sale of Indexes and Emmons Vols 313 00 Sale of Pyrometry 900 00 Sale of Raymond Vol 100 00 Interest received on Bank Balance . 500 00 Interest received on Life Memberships 500 00 Advertising-Gross 27,000 00 Voluntary Subscriptions-Estimated 16,000 00 Income from James Douglas Fund 5,000 00 Total $203,503 00

Jan 1, 1923

July 1-Sept. 30, Centennial of Engineering, Chicago. Aug. 28-29, Oak Ridge Summer Symposium, Oak Ridge, Tenn. Sept. 3-8, AIME, Industrial Minerals Div., annual fall regional meeting, Chicago. Sept. 3-6, AIME, fall meeting, Palmer House, Chicago. Sept. 3-13, AIME, Chicago Section, Centennial of Engineering, Chicago. Sept. 5-6, Engineers' Council for Professional Development, annual meeting, Hotel Sheraton, Chicago. Sept. 10-12, Porcelain Enamel Institute, annual shop forum, University of Illinois, Palmer House, Chicago. Sept. 11-13, American Institute of Chemical Engineers, Palmer House, Chicago, ill. Sept. 18, AIME, Utah Section, Newhouse Hotel, Salt Lake City. Sept. 22-25, American Mining Congress, Metal and Nonmetallic Mining Convention and Exposition, public auditorium, Denver.

Jan 1, 1952

By W. L. Doyle

SLAG weights were taken on a series of twenty-eight 6-ton bottom-pour heats. These weights varied from 573 to 1050 lb. Of these, four were chosen for study of the effect of cleaned and uncleaned foundry scrap on the variations of slag weights. Data regarding the make-up and results of the heats are given in Table I. For heat No. 3 the actual slag weight was checked, using the Mn-MnO calculation method-weight 1050 lb. [5,600 X 0.0055 = 30.80 heads and gates 6,000 X 0.004 = 27.00 plate scrap 800 X 0.0083 = 6.64 pig iron 450 X 0.0034 = 1.53 iron ore]

Jan 1, 1947

By M. G. Schuerger, D. W. Park

An improved gage for monitoring fractures in underground openings was successfully developed using the reflection photoelastic technique. The gage may be used to detect crack initiation in mine openings or tunnels so reme¬dial action may be taken to prevent further deterioration. Fringes concentrated around the cracks were spread by using rubber backing. Crack growth as little as 76µm (0.003 in.) up to as much as a 2.54-mm (0.1-in.) width were detect¬ed in this study. Variation of gage materials will provide alternative ranges. The feasibility of the method was tested and calibration was made in a laboratory study. Field study successfully demonstrated the capability of applications in detecting mine roof crack development.

Jan 1, 1984

By W. F. Mullen

WITH few exceptions, unit operations in the Pennsylvania slate industry in 1950 did not differ appreciably from production methods described by Behre1 and Bowles 2-4 several decades ago. Many traditionally picturesque but relatively inefficient hand operations continued to contribute to high operating costs in an industry in which the margin of profit, for various reasons, was admittedly low. As part of a general program in which the Pennsylvania State College has been assisting the slate industry to solve some of its problems, time and method studies were used in an effort to determine the bottlenecks of production flow. The results are as applicable to other stone industries as they are to slate.

Jan 12, 1951

By H. R. Deeth, C. J. Koenig

ABOUT ten years ago nepheline syenite was introduced to the ceramic industry and the material has now found application in the various branches of the industry, namely, as a vitrifying agent in white-wares and as a source of alumina and alkalies in glasses, glazes, and porcelain enamels. Spence1 described the early mining and processing developments regarding this material. Since the time of his article many research papers have appeared relating to the usage of nepheline syenite but little has been published relative to subsequent mining and processing methods. A complete indexed review of the literature was issued recently by Ohio State University.2 Since "Lakefield" nepheline syenite from Blue Mountain, Ontario (Fig I); is the only commercial ceramic-grade nepheline syenite now being marketed on this continent, discussion is limited to this operation carried on by American Nepheline Limited, Lakefield, Ont., and its subsidiary in the United States, American Nepheline Corp. at Rochester, N. Y. THE DEPOSIT Blue Mountain is a long ridge rising to an elevation of about 350 ft at its highest point above the surrounding country and extending for about six miles in a northeasterly direction across Methuen township, Peterborough County. The rock of the Blue Mountain central alkaline intrusive is fine grained, light colored and of even granitic texture. The solidified mass consists predominately of the minerals albite, nepheline and microcline in order of abundance. The average mineralogical composition for the deposit obtained by a study of 112 samples taken regularly over the whole formation is as follows:3 [VOLUMETRIC MINERAL PER CENT Albite54 Microcline20 Nepheline22 Muscovite2 Mafics2 (Biotite, hastingsite, magnetite) Total100] The mineral nepheline (or nephelite) belongs to the feldspathoid group but is lower in silica content than are the feldspars. It is a silicate of soda, potash, and alumina (NaKAl2O32SiO2). Its presence with albite (Na2O A1203 6SiO2) and microcline (K20 A12O3 6SiO2) gives the Blue Mountain deposit an alkali content of 15 pct and an alumina content of approximately 24 pct. While this huge alkaline mass is somewhat variable mineralogically, it has a uniform chemical composition. When the iron, mostly in the form of magnetite, is removed during processing, a remarkably uniform finished product is obtained. Geological surveying has disclosed many million tons of nepheline syenite in the Blue Mountain deposit. Diamond drilling in the area where mining is now being carried out indicates a block of about one million tons.

Jan 1, 1947

By Frederick C. Hull

THE grain size of a metal or alloy is one of the most important factors determining its properties. In steels, for example, grain size affects hardenability, toughness and machinability; in brasses, grain size is related to hardness and deep-drawing quality. In the field of heat-resistant alloys, grain size has a marked effect on ductility, creep and endurance strength. In order to determine these effects, as well as to control the properties of materials, many accurate and rapid measurements of grain size must be made. This paper presents a new and improved method for the estimation of grain size. USUAL METHODS of EVALUATING GRAIN SIZE A frequently used method of estimating grain size is that of comparing the image of a polished and etched specimen on the ground-glass screen of a metallographic microscope with standard grain-size charts. Several types of standards are available for use with different classes of microstructures. Geometric Grids.-The Metals Handbook1 has a series of hexagonal grids ranging in size from ASTM No. I to 8. Idealized Grain Networks.-Idealized grain-boundary networks for ASTM grain sizes I to 8 are included in the American Society for Testing Materials Tentative Standard E19-39T. Standard Micrographs.- The Metals Handbook and ASTM Tentative Standard EI9-39T contain micrographs of hypoeutectoid and hypereutectoid steels ranging in grain size from No. I to 8. The grain size of annealed brass (diam¬eter of the average grain in millimeters) is obtained by comparison with 10 micrographs of varying grain size in ASTM Tentative Standard Es-39T. A handicap to accurate evaluation of grain size by this method is the fact that it is difficult to compare photographs in a dimly lighted room with the image on the ground-glass screen, or, if the general illumination is increased so that the printed standards may be clearly seen, the contrast of the image of the unknown is decreased. It is easier to estimate grain size by comparing a micrograph of the unknown with the grain-size standards. However, photographing every specimen on which the grain size is desired is too costly in time and materials to be practicable. For hardened steels, the Shepherd or Jernkontoret fracture grain-size standards are very accurate and useful, but this method obviously cannot be applied to ductile alloys such as brass, stainless steels and austenitic heat-resistant alloys. Jeffries' method for grain-size measurements consists of counting the number

Jan 1, 1947

By J. J. Taber, I. S. K. Kamath, R. L. Reed

Alcohol floods of consolidated sandstone cores have shown the process to be strongly dependent on the phase behavior of the particular alcobol-oil-water system used. This means that in many cases the mechanism does not conform to the idea of a piston-like displacement. Instead, it is found that by changing the alcohol it is possible to change the relative velocities of the oil and water and, in fact, the entire mechanism of the process. The effects of rate, viscosity, initial saturation, distance travelled and hysteresis of relative permeability on the alcohol flooding mechanism are discussed. INTRODUCTION Reasons for interest in the use of alcohol to miscibly displace oil and water from a porous medium appear in the existing literature.l-7 The mechanism of the displacement has been considered and the apparent implications formulated into a theory which presumably would enable one to predict the essential features of the process.6 Unfortunately, most of the reported experiments have been performed with unconsolidated or artificially consolidated sands. With these systems some of the noteworthy facets of the process are obscured and resulting data appear uncertain. It is the purpose of this paper to show how the use of consolidated sandstones has led to revision of the mechanism and, hence, the theory of alcohol flooding. The practical result is increased pessimism toward the possibilities of commercial application of the simplest form of the alcohol-slug process. However, elucidation of the mechanism has made it possible to define the essential characteristics of a system of slugs which will behave in a nearly piston-like fashion and, thus, yield the best possible result. EQUILIBRIUM PHASE BEHAVIOR Fig. 1 is a diagram of the ternary system isopropyl alcohol (IPA)-Soltrol-calcium chloride brine. Brine was used to prevent plugging of the core and calcium chloride was used because sodium-chloride brine exhibits a solid phase with Soltrol and IPA. If alcohol is added in increments to the immiscible mixture of water and oil represented by Point A, the path followed by the successively equilibrated samples will be on the Line ABC and pass from the immiscible region to the miscible region by crossing the binodal curve at B. Consider the intersection D of this path with the tie Line EF. The quantity of oleic phase is proportional to the Segment ED and the quantity of the aqueous phase is proportional to DF. Compositions of the two phases are specified by Points E and F. It is clear that in the case shown the oleic phase is diminishing and entirely disappears when miscibility is achieved. Such will

By W. H. Ashby, R. W. Cassingham, C. R. Blomberg, J. B. Justins

The Brookhaven field is one of several Basal Tuscaloosa reservoirs located in south-central Mississippi. It is a standstone reservoir, of erratic deposition and with several faults, having an approximate subsea depth of 9,800 ft. A large variation in permeability exists with a weighted average being 256 md. Estimated average interstitial water saturation is 45 per cent. The undersaturated reservoir fluid exhibits marked differences in physical properties with measured saturation pressures ranging from 733 to 2,255 psi. Early rapid decline in reservoir pressure caused the operating interests to unitize the field and initiate a program of pressure maintenance by gas injection. At the time gas injection was commenced, the reservoir pressure had fallen to nearly half of the original pressure with only 4.5 Per cent of the original oil in place produced. The reservoir pressure has since been maintained at approximately 2,750 psig, and cumulative production to date is 17 per cent of original oil in place. An analysis of field performance during gas injection is presented in detail. The program of pressure maintenance by gas injection is considered to be a success, since the expected ultimate recovery has been increased and the current production rate is in excess of 2 per cent of original oil in place per year. Performance has been better, anticipated ultimate recovery is larger, and total production costs are lower than for a similar Basal Tuscaloosa reservoir nearby, even though that field appears to have a more effective natural water drive. INTRODUCTION The history of the Brookhaven Unit is a testimonial for unitization and for the application of engineering techniques in the operation of an oil field. The operating and royalty interests in this field have mutually benefited from their early recognition of the need for unitization and pressure maintenance and from the forthright manner in which these were accomplished. The tangible benefits accruing to the participants in the Unit are: (1) income from gasoline plant products, (2) reduced lifting and operating costs from those of competitive operation, (3) maintenance of high levels of current income by mitigation of the inevitable decline in production rates inherent to natural depletion, (4) an increase in ultimate recovery of about 40 per cent over natural depletion operations. This paper should properly be considered a progress report; however, the performance of the field after five years of pressure maintenance clearly indicates that the ultimate success of the project is assured. LOCATION AND GEOLOGY The Brookhaven field is located in south-central Mississippi, about six miles from the town of Brookhaven. Production at Brookhaven

Jan 1, 1955

By Pradeep K. Rohatgi, Clyde M. Adams

Dendritic aggregate of ice formed on freezing of aqueous soluitions has been studied. Chlorides of sodium, potassiutn, lithiunz , and hydroget1 were used as solutes. The spacing between ice platelets or den-drites was experimenlally found proportzonal to the square root of freezing time when the freezing rate was constant from beginrting to end of solidification; the constant freezing rates were obtained during freezing of small droplets of aqueous soliitions surrounded by relatively large heat sinks. The transverse growth velocity of the ice platelets is proportional to the square root of the freezing rate. During unidirectional freezing from a constant temperuture chill, the solution at each location is subjected to a spectrum of freezirtg rates. The freezing rate is ini- FREEZING of solutions has been a subject of investigation in many disciplines. Aqueous solutions offer the advantage of transparenty; their study is of special significance due to the increasing interest in freezing processes for desalination. In addition dendritic solidification of aqueous solutions is in many ways analogous to freezing of metallic solutions. Aqueous solutions of most ionic salts freeze with tially low, passes through a maximum, and then decreases until solidificatimz is complete. The den-drite spacing increases linearly with the distance from the chill surface; it is inversely profiortional to the square root of the maximum freezing rate. The dendrite spacings in the two systems (the constanl freezing rate and the varying freezing rate) are equal, when the maximum freezing rate of the varying freezing rate system equals the average freezing vale of the constant freezing rate system. Mass transport in interdendritic liquid duriug solidificatiotz is analyzed; the experimental observations indicate that maximum concentration difference (AC) and supercooling (AT) in the interdendritic liquid are indepexdent of freezing rate. the separation of practically pure ice crystals from the liquid phase; with very few exceptions there is no solid solubility of ionic salts in ice. As an ice crystal grows there is rejection of solute from the moving interface into the liquid. Since the rejected solute moves primarily by diffusion, concentration gradients are established in the liquid. The highest solute concentrations are found in liquid immediately adjacent to liquid-solid interfaces and lowest concentrations farthest from the interface. Two-phase equilibrium obtains only at the solid-liquid interface; at other locations the liquid becomes supercooled because temperature gradients are negligible compared to concentration gradients. This is an immediate consequence of the fact that thermal diffusivities are considerably higher than mass diffusivities.

Jan 1, 1968

By William J. McCaughey, Richard L. Barrett

For sixty years—in fact, ever since the inception of the basic steelmaking process —basic slags have been the subject of study by chemists, metallurgists and petrog-raphers! with the purpose of providing a better understanding of the reactions between the slag and the metal during the refining process. The result of this work and of the researches of mineralogists and physical chemists into the chemistry of oxide systems is a considerable body of literature dealing not only with slags themselves but with equilibrium relationships in systems synthesized from pure components. Since any actual slag is a multicom-ponent system more complex than any yet worked out in the laboratory, a complete solution to the problem is still far away. The writers have recently published a paper1 which they believe sheds light on the role of the slag in the elimination of phosphorus and it is the purpose of the present paper to discuss the metallurgical applications of that work. Since the pioneer investigations on the constitution of basic slags carried on by Stead and Risdale, Carnot and Richards, Hilgenstock and others in the I88o's, a considerable body of literature on this subject has appeared. Many of the more important of these papers were summarized in the previous paper,l therefore they will not be reviewed here. PetRographic Study The present writers have had occasion, over a period of years, to examine petro-graphically a great number of basic steel-making slags having a very wide range of chemical compositions and made under various conditions of operating practice. Although certain of these slags exhibit some unusual features, it is a remarkable fact that the great majority of mature slags show certain typical characteristics, which persist throughout the wide range of chemical compositions. The typical mature slag usually appears under the microscope to consist of two phases. The phase of primary crystallization is light colored and doubly refracting. If separated mechanically and subjected to chemical analysis, it is found to consist essentially of SiO2, CaO, and P2O6. Sometimes, although not usually, two such silicate-phosphate phases are found. The other conspicuous phase is dark in color and optically isotropic, and occurs as the interstitial material between the grains of the light colored phase. This dark colored interstitial phase when analyzed is found to consist essentially of FeO, Fe2O3, MnO, and MgO. In some 'lags high in iron oxide, particularly those from low-carbon heats, dicalcium ferrite is found. This phase is dark reddish brown in color and anisotropic.

Jan 1, 1944

By William J. McCaughey, Richard L. Barrett

For sixty years—in fact, ever since the inception of the basic steelmaking process —basic slags have been the subject of study by chemists, metallurgists and petrog-raphers! with the purpose of providing a better understanding of the reactions between the slag and the metal during the refining process. The result of this work and of the researches of mineralogists and physical chemists into the chemistry of oxide systems is a considerable body of literature dealing not only with slags themselves but with equilibrium relationships in systems synthesized from pure components. Since any actual slag is a multicom-ponent system more complex than any yet worked out in the laboratory, a complete solution to the problem is still far away. The writers have recently published a paper1 which they believe sheds light on the role of the slag in the elimination of phosphorus and it is the purpose of the present paper to discuss the metallurgical applications of that work. Since the pioneer investigations on the constitution of basic slags carried on by Stead and Risdale, Carnot and Richards, Hilgenstock and others in the I88o's, a considerable body of literature on this subject has appeared. Many of the more important of these papers were summarized in the previous paper,l therefore they will not be reviewed here. PetRographic Study The present writers have had occasion, over a period of years, to examine petro-graphically a great number of basic steel-making slags having a very wide range of chemical compositions and made under various conditions of operating practice. Although certain of these slags exhibit some unusual features, it is a remarkable fact that the great majority of mature slags show certain typical characteristics, which persist throughout the wide range of chemical compositions. The typical mature slag usually appears under the microscope to consist of two phases. The phase of primary crystallization is light colored and doubly refracting. If separated mechanically and subjected to chemical analysis, it is found to consist essentially of SiO2, CaO, and P2O6. Sometimes, although not usually, two such silicate-phosphate phases are found. The other conspicuous phase is dark in color and optically isotropic, and occurs as the interstitial material between the grains of the light colored phase. This dark colored interstitial phase when analyzed is found to consist essentially of FeO, Fe2O3, MnO, and MgO. In some 'lags high in iron oxide, particularly those from low-carbon heats, dicalcium ferrite is found. This phase is dark reddish brown in color and anisotropic.

Jan 1, 1944

By John Randall

It is a fair assumption that the main purpose of any diagram is to present facts to the eye in more convenient form than they could be tabulated in figures, and this implies that a screen diagram should set forth in a convenient and familiar form certain facts as to the character of the material screened regardless of the screen standards used, and it seems particularly desirable on account of the well-known differences in the size of openings of different laboratory screens having the same nominal mesh. In making screen-sizing tests it has been customary first to consider the largest size, going progressively to the smallest, and this seems to have led to the practice of placing the smallest size .at the right-hand side of the diagram and measuring toward the left. This is not altogether convenient and might be changed to advantage, but for illustration I have preserved that feature and present the method just as I have used it for over 2 years. Direct plotting in which the intervals on the diagram are proportional to the sizes of the openings, or to the arithmetical difference between them, seems at first sight more natural and is extremely useful for certain purposes, but it makes the diagram very crowded in the smaller screen sizes while the larger ones occupy unnecessary space, making it less convenient for most purposes, and for that reason the method here discussed is the well-known one based on the ratio between openings, and is plotted in logarithms instead of the direct values of the screen opening. Metric coordinate paper is convenient, although not necessary; it is recommended, as the use of the metric scale gives a diagram of convenient size, but any scale of equal parts may be used. In order to make any screen diagram translatable in terms of any standard screen size, it is necessary to have noted on the size scale of the diagram all points corresponding to the openings of the various screens in question, instead of a single series of points as with a single screen. In drawing the diagram assume 0.001 in. (corresponding approximately to 0.025 mm.) to be the smallest size to be considered and fix this as the zero point at the lower right-hand corner of the diagram. This value is selected because the values are to be plotted in logarithms, and the logarithm of 1 is zero. Then lay off to the left for the position of each screen

Jan 1, 1918

By William J. McCaughey, Richard L. Barrett

FOR sixty years-in fact, ever since the inception of the basic steelmaking process -basic slags have been the subject of study by chemists, metallurgists and petrographers, with the purpose of providing a better understanding of the reactions between the slag and the metal during the refining process. The result of this work and of the researches of mineralogists and physical chemists into the chemistry of oxide systems is a considerable body of literature dealing not only with slags themselves but with equilibrium relationships in systems synthesized from pure components. Since any actual slag is a multicomponent system more complex than any yet worked out in the laboratory, a complete solution to the problem is still far away. The writers have recently published a paper1 which they believe sheds light on the role of the slag in the elimination of phosphorus and it is the purpose of the present paper to discuss the metallurgical applications of that work. Since the pioneer investigations on the constitution of basic slags carried on by Stead and Risdale, Carnot and Richards, Hilgenstock and others in the 1880's, a considerable body of literature on this subject has appeared. Many of the more important of these papers were summarized in the previous paper,' therefore they will not be reviewed here. PETROGRAPHIC STUDY The present writers have had occasion, over a period of years, to examine petrographically a great number of basic steel- making slags having a very wide range of chemical compositions and made under various conditions of operating practice. Although certain of these slags exhibit some unusual features, it is a remarkable fact that the great majority of mature slags show certain typical characteristics, which persist throughout the wide range of chemical compositions. The typical mature slag usually appears under the microscope to consist of two phases. The phase of primary crystallization is light colored and doubly refracting. If separated mechanically and subjected to chemical analysis, it is found to consist essentially of SiO2, CaO, and P2O5. Sometimes, although not usually, two such silicate-phosphate phases are found. The other conspicuous phase is dark in color and optically isotropic, and occurs as the interstitial material between the grains of the light colored phase. This dark colored interstitial phase when analyzed is found to consist essentially of FeO,Fe2O3, MnO, and MgO. In some slags high in iron oxide, particularly those from low-carbon heats, dicalcium ferrite is found. This phase is dark reddish brown in color and anisotropic.

Jan 1, 1944

INTRODUCTION TO SAMPLING THEORY Before specifically discussing mineral sampling and sampling procedures, let us briefly consider broader and more universal concepts of modem sampling theory. A sample is de- fined as a representative part or a single item from a larger whole, being drawn for purpose of inspection or shown as evidence of quality. In modem theory the sample is a part of a statistical population whose properties are studied to gain information about the whole. The theory of sampling is built around the concept that if enough representative units of a larger overall population are selected without bias, the average value of the units will approximate that of the total population. Modem theory attempts to answer the question of how many samples are enough, given certain limits and constraints, and seeks to apply methods of sample selection and of estimation that provide, at the lowest possible cost, estimates that are precise enough for the purposes at issue. In order to meet these objectives the designer of a sample survey must rely heavily upon statistical theory. Statistics has been defined as the collection, presentation, analysis, and interpretation of numerical data. Statistical methods are primarily concerned with making valid inferences about a population based upon samples taken from the population. For most statistical applications, the total sample is in terms of number of items, attributes, or things; whereas mineral samples are usually in terms of weight or volume of mineral particles. Certain steps are involved in a well designed sample survey without regard to the particular field of application. Because the desired characteristics of an unmined mineral deposit can- not be known other than by sampling, we will consider these principle steps in terms of a mineral sample survey: 1) Clear definition of the objectives of the survey. In the case of mineral sampling this step is so apparent as to be almost ridiculous. However, it is surprising how often the overall objective of a sampling program is overlooked when decisions are made on a day-today basis. 2) Definition of the population to be sampled. The word population is used to designate the aggregate from which the sample is chosen. A sampling program may be designed to determine the grade of a single stope within a mine, the grade of a particular zone within a complex ore body, or the total value and extent of a mineral deposit. Since mineral sampling is usually done in phases, it is well to

Jan 1, 1980

By H. L. Riley, B. W. Gandrud

A froth flotation unit was added to the DeBardeleben Coal Corporation's Empire washer at Empire, Alabama, in the fall Of I94O following an investigation of possible ways and means of recovering coal values from settling-tank overflow or slurry. Officials of the DeBardeleben corporation hoped that some practical and reasonably economical way could be found for recovering fine coal from overflow water, although there had as yet been very little progress along this line in the Alabama coal fields. The Bureau of Mines was asked to cooperate in the project through its Southern Experiment Station, at University, Alabama. This paper presents a brief description of the process and the installation that resulted from the investigation of the overflow water or slurry problem at the Empire mine. The experimental data include' as a Part of this Paper were obtained during the course of the investigation in 1940 Since that time, however, the flotation unit has been running more or less continuously without significant operational changes and is still Performing pretty much in accordance with the data obtained in 1940. Flowsheet at Empire and Type of Coal Treated The Empire mine is developed on the Black Creek bed near the the border of the Warrior field. The coal in this bed is extremely low-ash and although there is an almost complete absence of bone coal and partings, the bed is so thin that, with mechanized mining, a high percentage of rock from roof and floor inevitably gets into the run-of-mine coal. The thickness of the Black Creek bed throughout the part of the Warrior field in which it is mined extensively is rarely over 30 in. and probably would average about 25 in, the coal is of the high-volatile A rank and of excellent quality, but as a result of admixture of roof and floor material, the run-of-mine product usually contains I ; to 20 pct rock by weight. he following is a proximate analysis on an "as-received " basis of a typical seam sample from the Empire mine:' moisture, 3.0 pet; volatile, 34.6 fixed carbon 58.3; ash, 4.1 This sample shelved 15,070 Btu per pound and 0.9 pct sulphur on a moisture-and-ash-free basis. In the Empire preparation plant the lump sizes above 3 in. are removed and hand-picked on a Marcus conveying Screen, the 3 to ? -in. size is removed by vibrating screens and washed in two Montgomery single-cell jigs, and the ?-in. to o slack is cleaned on four diagonal

Jan 1, 1949

By John Randall

IT is a fair assumption that the main purpose of any diagram is to present facts to the eye in more convenient form than they could be tabulated in figures, and this implies that a screen diagram should set forth in a convenient and familiar form certain facts as to the character of the material screened regardless. of the screen standards used, and it seems particularly desirable on account of the well-known differences in the size of openings of different laboratory screens having the same nominal mesh. In making screen-sizing tests it has been customary to first consider the largest size, going progressively to the smallest, and this seems to have led to the practice of placing the smallest size at the right-hand side of the diagram and .measuring toward the left. This is not altogether convenient and might he changed to advantage, but for illustration I have preserved that feature and present the method just as I have used it for over 2 years. Direct plotting in which the intervals on the diagram are proportional to the sizes of the openings, or to the arithmetical difference between them, seems at first sight more natural and is extremely useful for certain purposes, but it makes the diagram very crowded in the smaller screen sizes while the larger ones occupy unnecessary space, snaking it less convenient for most purposes, and for that reason the method here discussed is the well-known one based oil the ratio between openings, and is plotted in logarithms instead of the direct values of the screen opening. Metric coordinate paper is convenient, although .not necessary; it is recommended, as the use of the metric scale gives a diagram of convenient size, but any scale of equal. parts may be used. In order to make any screen diagram translatable in terms of any standard screen size, it is necessary to have rioted on the size scale of the diagram all points corresponding to the openings of the various screens in question, instead of a single series 'of points as with a single screen. In drawing the diagram assume 0.001 in. (corresponding approximately to 0.025 mm.) to be the smallest size to be considered and fix this as the zero point at the lower right-hand corner of the diagram. This value is selected because the values are to be plotted in logarithms, and the logarithm of 1 is zero. Then lay off to the left for the position of each screen

Jan 9, 1917

By L. G. Truby

DISCUSSION By Rhrt G. Nisle, Phillips Petroleum Co., Barthesville, Okla. The subject paper presents the results of a reservoir behavior analyzer study of the pressure-production performance of five Ellenburger pools in West Texas. These five pools are Wheeler, TXL, Andector, Embar, and Martin. This laboratory has also made reservoir behavior analyzer studies in this area and arrived at substantially the same conclusions. Although the principal results of the studies made in this laboratory are confirmed by the results in the subject paper, there are certain points of difference. The points of difference are (1) the subject paper includes the Martin pool in the common aquifer, whereas our studies indicate that it is not, and (2) the subject paper concludes that the effective aquifer is considerably smaller than that derived from studies made in this laboratory. In terms of reservoir analyzer data, our rejection of Martin is based on the inability to obtain a satisfactory match of the pressure curve when Martin is considered as lying within the common aquifer. A satisfactory match was possible, however, when Martin was run as an isolated pool. This indicates that the pressure disturbance resulting from production at Martin had not reached Embar, Andector, TXL, or Wheeler at the time of our study. A similar situation exists relative to Dollarhide. In tern of geological data, our rejection of Martin is based on the presence of a faulted zone between Martin and Embar. This condition is indicated in Fig. 4 and again in Fig. 10 of the subject report. If a permeable connection between Martin and the other fields does exist, it is probably by way of a detour around this fault. The second point of difference between the two studies is illustrated by a comparison of Fig. 4 of the subject paper with Eg. A. Fig. A is obtained from an internal report on one of the studies made by this laboratory. It will be noted that the area indicated in Fig. 4 is roughly that marked "Pool Unit" in Fig. A. The additional portion of the aquifer shown in Fig. A was simulated on the reservoir analyzer by means of the water drive network. A satisfactory pressure match could not be obtained without this additional network. The differences involved here stem from a more fundamental consideration concerning reservoir analyzer operating techniques. The true source of these differences in reported results cannot at this time be determined because of the incompleteness of the subject paper. It is not stated, for instance, whether the pressure match was induced by altering the field resistance or the field capacitance, or both. Changing analyzer

Jan 1, 1953