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By D. V. Doane, G. A. Timmons, W. G. Scholz

Molybdenum of high purity can be produced by direct dissociatiott of commercial molyhdenm disulfide in vacuo at 1600° to 1700°C (2910° to 3090°F). The Product is lower in oxygen than commercially available molybdenzdm powder. Analyses of ingots arc-cast from commercial molybdenum powder, hydrogen-re-cluced from animonium molybdate, and from thermally dissociated molybdenum disulfide indicate that the levels of chemical impurities in these ingots are similar. Equipment now in operation will produce 100-lb hatches of powder product. The paper describes development of processing equipment, control of processing varzahles, handling of the product, and evaluatiotl of the melal produced. MOLYBDENITE (molybdenum disulfide) can be decomposed by heat in the absence of oxygen to produce elemental molybdenum and sulfur, which is evolved as a gas. The temperatures required for the dissociation are above 1370°C (2500°F); the sulfur must be continuously withdrawn to permit the reaction to proceed to completion. This is accomplished by continuous evacuation of the thermal dissociation chamber and condensation of the gaseous sulfur in another part of the system. Cognizance of the fact that the dissociation takes place in two steps is important in controlling the process. Basically, the molybdenite dissociation process has two potential advantages as a method of produc- ing pure molybdenum: 1) The materials entering into the process contain little or no oxygen. Since the process is carried out in vacuum at high temperature, the quantities of interstitial oxygen, nitrogen, and hydrogen in the product should be very low. 2) The process is more direct than the commercia1 method of producing high-purity molybdenum. In the conventional process, molybdenite is roasted to molybdic oxide, the oxide is purified first by sublimation, then by conversion to ammonium molybdate, and finally, the molybdate is reduced in a hydrogen atmosphere (usually in two steps) to the metal lic molybdenum powder. This paper presents a description of the stages in scaling-up of the dissociation equipment and an account of attempts to evaluate the molybdenum produced by thermal dissociation, rather than a report of a fundamental study of the dissociation reaction. Since little has been written on the subject, it is appropriate, before detailing the development of the process, to review briefly the research that has been conducted over quite a period of years. LITERATURE SURVEY The first accounts of the possibility of thermal dissociation of the mineral molybdenite were re-

Jan 1, 1962

By T. A. Pollard, C. R. Sandberg, E. B. Elfrink

This paper presents an evaluation of compressibility factor data and a discussion of their application to the estimation of gas reserves. A correlation is presented which provides compressibility factors for use in both two-phase and single-phase hydrocarbon systems. Accuracies comparable to those obtained previously for single-phase systems only can be expected. A simple means of predicting the presence or absence of a liquid phase in a condensate system of known composition is illustrated. The correlation is based on 1,030 compressibility determinations from 21 hydrocarbon samples taken from eight oil fields. Of the data used, 75 per cent were from California, 15 per cent were from the Mid-Continent area, and 10 per cent were from South America. The average numerical deviation of the experimental data from this compressibility chart is 1.22 per cent. Charts and tables are included and discussed which illustrate the errors involved through the misuse or nonuse of compressibility factors in estimates of gas-in-place. INTRODUCTION The compressibility factor is a coefficient which expresses the deviation of a gas of given composition from the Perfect Gas Laws. A factor such as this is necessary in any calculation involving volumes of gaseous mixtures, and finds extensive application in the estimation of natural gas and condensate reserves. It is used in the decline curve, the volumetric, and the material balance methods of gas reserves estimation. The behavior of gases at high pressures has been investigated extensively in recent years and considerable data have been assembled on the compressibility characteristics of a number of gases. Notable among the investigators of high pressure gas relationships are Kvalnes and Caddya, Kay" Sage and Laceys, and Brown, Standing" and Katz4. Other contributors are Smith and Watson, Roland and Kaveler', and Stevens and Vance". The data on compressibility factors assembled by these investigators have been presented and correlated in numerous ways; particularly noteworthy is the method first presented by Kay5 which relates compressibility factor "Z" to pseudo-reduced temperature and Pseudo-reduced pressure. Other investigators have used this empirical relationship successfully and numerous charts covering a large number of gases have been constructed on this basis. It is the purpose of this paper to evaluate compressibility factor data and to illustrate the importance of their proper use in the estimation of gas-in-place for both gas and condensate reservoirs. EVALUATION OF COMPRESSIBILITY FACTOR DATA The compressibility chart presented by Standing, Katz, Brown and Holcomb in 1941 is probably the most recent and reliable chart for natural gases. The reliability of the Katz chart has been investigated by the writers for a fairly large number of gases (single-phase) in the pressure range from 500 to 10,000 psia and temperature range from 80 to 400°F. A summary of this comparison is presented in Table I. The numerical average deviation of the chart compressibility factors from the experimental compressibility factors is 1.05 per cent, and the algebraic deviation is -0.28 per cent. The Katz correlation appears to be quite accurate for single-phase hydrocarbon systems. It was based on single-phase systems and does not necessarily provide a means of accurately predicting the behavior of two-phase systems which might be encountered in condensate work. Data published recently by Sage and Oldsl' have enlarged the knowledge of phase behavior in condensate systems by covering extensively the Compressibilities of systems in the two-phase as well as single-phase regions for a wide range of temperatures, pressures and gas-oil ratios. An evaluation of these data indicates that conditions can arise, especially in condensate systems having fairly low gas-oil ratios, in which two phases occur and the usual gaseous compressibility factors do not accurately apply. The measured PVT data of Sage and Olds covering two-phase systems have been correlated with additional such data from the Mid-Continent area and South America; these are presented in Fig. 1. This chart is the result of 1,030 compressibility* determinations from 21 hydrocarbon samples taken from eight oil and condensate fields. Of the data used, 74.75 per cent were from California, 15.45 per cent were from the Mid-Continent area, and 9.80 per cent were from South America. The chart construction is based on the original

Jan 1, 1949

By C. R. Sandberg, T. A. Pollard, E. B. Elfrink

This paper presents an evaluation of compressibility factor data and a discussion of their application to the estimation of gas reserves. A correlation is presented which provides compressibility factors for use in both two-phase and single-phase hydrocarbon systems. Accuracies comparable to those obtained previously for single-phase systems only can be expected. A simple means of predicting the presence or absence of a liquid phase in a condensate system of known composition is illustrated. The correlation is based on 1,030 compressibility determinations from 21 hydrocarbon samples taken from eight oil fields. Of the data used, 75 per cent were from California, 15 per cent were from the Mid-Continent area, and 10 per cent were from South America. The average numerical deviation of the experimental data from this compressibility chart is 1.22 per cent. Charts and tables are included and discussed which illustrate the errors involved through the misuse or nonuse of compressibility factors in estimates of gas-in-place. INTRODUCTION The compressibility factor is a coefficient which expresses the deviation of a gas of given composition from the Perfect Gas Laws. A factor such as this is necessary in any calculation involving volumes of gaseous mixtures, and finds extensive application in the estimation of natural gas and condensate reserves. It is used in the decline curve, the volumetric, and the material balance methods of gas reserves estimation. The behavior of gases at high pressures has been investigated extensively in recent years and considerable data have been assembled on the compressibility characteristics of a number of gases. Notable among the investigators of high pressure gas relationships are Kvalnes and Caddya, Kay" Sage and Laceys, and Brown, Standing" and Katz4. Other contributors are Smith and Watson, Roland and Kaveler', and Stevens and Vance". The data on compressibility factors assembled by these investigators have been presented and correlated in numerous ways; particularly noteworthy is the method first presented by Kay5 which relates compressibility factor "Z" to pseudo-reduced temperature and Pseudo-reduced pressure. Other investigators have used this empirical relationship successfully and numerous charts covering a large number of gases have been constructed on this basis. It is the purpose of this paper to evaluate compressibility factor data and to illustrate the importance of their proper use in the estimation of gas-in-place for both gas and condensate reservoirs. EVALUATION OF COMPRESSIBILITY FACTOR DATA The compressibility chart presented by Standing, Katz, Brown and Holcomb in 1941 is probably the most recent and reliable chart for natural gases. The reliability of the Katz chart has been investigated by the writers for a fairly large number of gases (single-phase) in the pressure range from 500 to 10,000 psia and temperature range from 80 to 400°F. A summary of this comparison is presented in Table I. The numerical average deviation of the chart compressibility factors from the experimental compressibility factors is 1.05 per cent, and the algebraic deviation is -0.28 per cent. The Katz correlation appears to be quite accurate for single-phase hydrocarbon systems. It was based on single-phase systems and does not necessarily provide a means of accurately predicting the behavior of two-phase systems which might be encountered in condensate work. Data published recently by Sage and Oldsl' have enlarged the knowledge of phase behavior in condensate systems by covering extensively the Compressibilities of systems in the two-phase as well as single-phase regions for a wide range of temperatures, pressures and gas-oil ratios. An evaluation of these data indicates that conditions can arise, especially in condensate systems having fairly low gas-oil ratios, in which two phases occur and the usual gaseous compressibility factors do not accurately apply. The measured PVT data of Sage and Olds covering two-phase systems have been correlated with additional such data from the Mid-Continent area and South America; these are presented in Fig. 1. This chart is the result of 1,030 compressibility* determinations from 21 hydrocarbon samples taken from eight oil and condensate fields. Of the data used, 74.75 per cent were from California, 15.45 per cent were from the Mid-Continent area, and 9.80 per cent were from South America. The chart construction is based on the original

Jan 1, 1949

By J. L. Sepulveda, R. F. Yap, R. Jauregui

INTRODUCTION The Third Theory of Comminution, oftentimes called the Bond Theory, was first published by Fred C. Bond in 1952. Since then, it has been widely used in the milling industry to size crushing and grinding equipment as well as to predict and evaluate their performance. Although two other comminution theories were advanced almost a century earlier, one by Rittinger, 1867, and the other by Kick, 1885, their use was limited because they did not agree with actual commercial comminution systems (Bond, 1961). According to Bond's Third Theory, the work input is proportional to the new crack tip length produced in particle breakage, and equals the work represented by the product minus that represented by the feed. For particles of similar shape, the crack tip length is equivalent to the square root of one-half the surface area, and the new crack length is proportional to [(1/vT - vF)]; where P and F are particles diameter of product and feed, respectively. For practical calculations, the particle diameter can be expressed in terms of the 80% passing sizes, P and F, respectively. Therefore, the work input is given by, [10 _ 10', W = Wi [7P_7F(1)] Where W = the energy input to the mill, (kwh/t) Wi = Work Index, (kwh/t) P = square sieve opening which 80% of the product passes, (microns) F = square sieve opening which 80% of the feed passes, (microns) Equation (1) is the mathematical statement of the Third Theory, or the Bond equation. Numerically, the work index is the energy required in kwh/t to reduce a given material from theoretically infinite feed size to 80% passing 100 microns. The work index of a particular material is determined in the laboratory by conducting the standard Bond grindability test. Bond developed separate tests for the rod mill and the ball mill. The simplified test method described in this paper, which is used at Anaconda Research Center to approximate the work index, is an alternative procedure to the ball mill

Jan 1, 1982

By T. D. Thomas

CONTENTS PAGE T. D. Thomas-Misfires in Anthracite Coal Mines 3 W. H. Forbes-Misfires in Bituminous Coal Mines 12 A. W. Worthington-Misfires in Non-metallic Mining (Limestone) 18 Misfires in Anthracite Coal Mines BY T. D. THOMAS,* LANSFORD, PA. (New York Meeting, February, 1929) IN THIS paper, major attention is given to misfires in mines where electric multiple shot-firing is the system used. Misfires are sometimes caused by one action or condition and at other times by a combination of two or more. They may be divided into two classes: (1) those caused by workers in the mines, (2) mechanical or manufacturer's causes. The second cause will be discussed first. MISFIRES CAUSED BY FAULTY DETONATORS The important part of an electric blasting cap, to the user where multiple shot-firing is done, ass in the steep-pitch, thick-vein, anthracite mines, is the bridge wire. In single shot-firing this factor is not apparent, but in mines where multiple firing is done any variation in the resistance of the bridge wire, where full or even rated battery capacity is required, will most likely cause a misfire The reason for this is obvious. If the resistance in the bridge wires is not the same, some of the detonators will fire because of their greater comparative resistance. Variance in resistance of bridge wires is caused by a slight difference in the diameter of the bridge wire, also to a difference in the composition of the bridge wires. Again, where the bridge wires have become rusted, there will be a variance in resistance. About the year 1922, one of the large coal companies was greatly alarmed by the number of serious and fatal accidents caused by misfires. The general manager issued an order that these accidents must be greatly reduced, and if possible, entirely prevented.

Jan 1, 1929

By S. J. Kidder

Application of shrinkage stoping methods, without filling, in the mining of large silver-gold orebodies in the Mogollon district, where the ore is hard and wall rocks stand well without timbering and where veins make little water. Vertical and inclined shafts in use with both surface and underground hoisting stations. Storage pockets used on main hoisting levels, with electric signals and telephones for communication. Power is generated by De La Vergne engines having a total sea-level rating of 1540 hp. On account of the remote location of the camp, transportation is an important item of expense, amounting in 1922 to $0.641 per ton of ore milled or $0.265 per ton-mile on all freight hauled. THE Mogollon mining district is in the southwestern part of New Mexico near the southern end of the Mogollon range, from which the district takes its name. The town of Mogollon is but 37 1/2 mi. in an air line northeast of Clifton, Ariz. The air-line distance from Silver City is 52 1/2 mi. and from Tyrone, 57 mi. Supplies are transported by motor truck from Silver City. The distance by road is 75 mi., half of which is an improved highway of modern construction. Transportation has always - been a large item of expense in carrying on operations in the district. Valuable ore is said to have been discovered in the Mogollon Mountains as early as 1870 but the first regular prospecting was carried on in 1875, by James C. Cooney, a sergeant from Fort Bayard. His discovery of rich silver-copper ores in the region of Mineral Creek led to the establishment of the Camp of Cooney. Remote from any settlements where there was a semblance of law and order, and harassed by the Apaches, development was slow and nearly 10 years elapsed before the village of Mogollon was established on Silver Creek. Prospecting in this section of the district had disclosed the outcrops of several promising veins containing silver-gold ores. Among the early claims located were the Last Chance, Top and Confidence, on what has proved to be the most productive vein in the district.

Jan 3, 1924

By Dr. O’Neil Thomas J., Donald W. Gentry

Who steals our gold and silver, and copper, zinc and lead? Who takes the joy all out of life and strikes our high hopes dead? Who never wrote a schedule that to anyone else was clear? The sulphur-belching, miner-welching, smelter engineer. -Anonymous From "The Engineer," Engineering & Mining Journal, Apr. 13, 1918 INTRODUCTION A striking characteristic of publications devoted to the principles of engineering economy and investment analysis is that the revenue side of the equation is generally either ignored entirely or addressed only in a superficial manner. This is understandable to a degree in the general case because methods of revenue estimation are highly dependent upon the specific type of project under consideration and the nature of the market served. An important contributing factor, however, is that developing estimates of future sales prices for most products is a risky activity which is less amenable to credible quantitative modeling than other topics in investment analysis. The specific subset of capital intensive investments addressed in this book- mining projects-is particularly sensitive to projections of mineral prices, many of which are notoriously volatile. Furthermore, the unique nature of mineral markets, prices, and product specifications occupies a major role in mineral project evaluation. Even here, however, authors have tended to offer little assistance to the reader in estimating project revenues. For example, the most popular mining engineering textbook for four decades, Elements of Mining (Lewis and Clark, 1967), contains the following advice on estimating future mineral prices (pp. 359-360): "Since the life of the mine will extend over a number of years the future price of mineral products must be estimated in order to calculate the probable profit to be realized. Current prices may be used, but it is preferable to take the average price for the past 25 to 35 years as it covers definite business cycles. Some engineers believe that a mine should make a small profit if its highest-grade ore is marketed at the minimum price during the past 35 years. Business

Jan 1, 1984

THIS paper presents briefly some of the principal results of 3 ½ months field work during the summer of 1938 in the Chichagof mining district, southeastern Alaska. The report is preliminary and presumably will be followed later by a more complete report to be published by the Geological Survey. The paper is concerned principally with the structural geology of a block of steeply dipping graywacke as revealed underground in the Hirst Chichagof and the Chichagoff mines, the two principal mines of the district. The two mines have produced about $16,000,000 worth of gold and silver. The attitude of the graywacke, which is locally cut by dikes and sills of aplite, is remarkably uniform and trends about N. 62º W. The average dip is about 67º SW. The graywacke is cut by large faults, the best known of which are the Hirst and the Chichagof, whose average trends are about N. 30ºW. and average dips about 75º SW. The faults at some places split into the bedding of the graywacke and at others are deflected from their normal trends for considerable distances along the bedding. The relative movements along the faults was northwest and up at about 30º for the south- west or hanging-wall sides. The ore bodies are elongate quartz lenses in the faults. Most of the quartz is mineralized but locally large quartz masses are too low grade to be mined. The emplacement of the ore bodies appears to have been structurally controlled in large part by the intersections of the faults with the bedding surfaces. Places where the faults split or are deflected appear to have been particularly favorable places for ore deposition. There has been some post-quartz movements along the faults but it is thought that such movements have not been extensive enough to greatly modify the original positions and shapes of the ore bodies.

Jan 1, 1939

By J. M. Donkers, R. de Groot

The various objectives of dredging at sea require different methods and radically different equipment for their optimum fulfillment. In the majority of cases, sea dredging is done by means of dredging equipment connected to a pontoon or ship floating at the surface. As the supporting hull is subject to the influence of waves, swells, currents and wind, the connecting point of the dredging equipment to the hull will generally move relative to the sea bottom with 6° of freedom. The more important hull motions are surge, heave, pitch and roll. Depending on the actual sea and weather conditions and the size of the hull, some of these motions can be so large that dredging equipment of rigid construction (normal or inland dredges) cannot be used. In those cases where mechanical disintegration of the bottom is necessary and where accurate dredging is required, the designer must find a solution for this problem. For cases where the bottom consists of soils that can be handled by plain suction, highly sophisticated dredging equipment such as the trailing suction hopper dredge permit dredging under all but the most severe sea state conditions. This type of dredge picks up the soil from the sea bottom while slowly underway. The drag suction head is fitted on a suction pipe of such flexibility that the supporting ship can carry out all six movements in relation to the draghead (heave, pitch, roll, sway, yaw and surge), while the draghead remains in firm contact with the bottom. The suction pipe is fitted with flexible hoses, a universal hinge, a horizontal hinge, axial turning gland and sliding turning gland with horizontal axis and is suspended flexibly from the ship incorporating swell compensating buffer gear, keeping the wires taut and the draghead bottom contact pressure fairly constant while the dredge moves up and down. Due to the fact that the draghead has a low bottom contact pressure and has little tendency to sink into the bottom, this compensation is not difficult to realize.

Jan 4, 1974

By H. F. Winham

The history, development, subsurface geology, production, economics and estimated reserves are discussed in this paper. The Magnolia structure is an anticline with a known maximum structural relief at 372 ft., and the areal extent of the producing acreage is 4494 acres. Production is obtained from the Smack-over oölitic lime and 116 successful wells have been drilled. The field, which was developed on 40-acre spacing, has been under strict control. It is believed to be producing with a strong water drive, To date it has produced more than eighteen million barrels and the estimate of ultimate recovery is 220 million barrels. Early History The Magnolia field is in colurnbia County, Arkansas, T. 17 s., R. 19 and 20 W. Various geologists had long been interested in this general area, and as early as 1921, John F. Magale was able to define a surface structure. The first wildcat, one of the first in Columbia County, was drilled in 1923 by Mid-States Oil Co., in sec. 10, T. 17 S., R. 20 W. This well was about 11/2 miles northwest of the Kerlyn oil Company's discovery well and was based on surface geological work done by Jewel and Dobie. Subsequently, several shallow wells that were not carried below the Upper Cretaceous beds were drilled in the immediate area of the discovery well, but none of them contained any commercial showings of oil Or gas. In the latter part of 1935, Elam and Magale (or Southwood) Garrett NO. I was located in sec. 13, T. 17 S., R. 20 W., 3/4 mile east of the discovery well. It was drilled to a total depth of 4018 ft. in the lowermost Glen Rose beds but failed to obtain any showings of oil or gas. Interest had been stimulated in this general area, however, by the discovery of several oil fields, mainly Glen Rose oil production in the Rodessa field in Louisiana in 1935, Smackover lime productioil in Snow Hill in May 1936, production from the Cotton Valley formation in Schuler in 1937, and Smackover lime production from the Buckner field in November 1937. With this background and subsequent seismic work, which was carried on partly because the old shallow wells drilled in the township had shown evidence of closure in the Upper Cretaceous beds, the discovery well, Kerlyn Oil Company's Barnett No. I, Sec. 14, T. 17 S., R. 20 W., was originally projected to a total depth of 6300 ft., to test the equivalents of the Morgan sands of the Cotton Valley series, then producing at Schuler. The well was carried to a depth of 6325 It. and tested the objective beds without finding commercial production. In the meantime, however, one well had found production in the Jones sand and another in the Smaclrover lime at Schuler. Kerlyn immediately made arrangements to deepen the Barnett well to the Smackover lime. The top of the Smackover lime was encountered at 7618 ft. and the well

Jan 1, 1943

By H. F. Winham

The history, development, subsurface geology, production, economics and estimated reserves are discussed in this paper. The Magnolia structure is an anticline with a known maximum structural relief at 372 ft., and the areal extent of the producing acreage is 4494 acres. Production is obtained from the Smack-over oölitic lime and 116 successful wells have been drilled. The field, which was developed on 40-acre spacing, has been under strict control. It is believed to be producing with a strong water drive, To date it has produced more than eighteen million barrels and the estimate of ultimate recovery is 220 million barrels. Early History The Magnolia field is in colurnbia County, Arkansas, T. 17 s., R. 19 and 20 W. Various geologists had long been interested in this general area, and as early as 1921, John F. Magale was able to define a surface structure. The first wildcat, one of the first in Columbia County, was drilled in 1923 by Mid-States Oil Co., in sec. 10, T. 17 S., R. 20 W. This well was about 11/2 miles northwest of the Kerlyn oil Company's discovery well and was based on surface geological work done by Jewel and Dobie. Subsequently, several shallow wells that were not carried below the Upper Cretaceous beds were drilled in the immediate area of the discovery well, but none of them contained any commercial showings of oil Or gas. In the latter part of 1935, Elam and Magale (or Southwood) Garrett NO. I was located in sec. 13, T. 17 S., R. 20 W., 3/4 mile east of the discovery well. It was drilled to a total depth of 4018 ft. in the lowermost Glen Rose beds but failed to obtain any showings of oil or gas. Interest had been stimulated in this general area, however, by the discovery of several oil fields, mainly Glen Rose oil production in the Rodessa field in Louisiana in 1935, Smackover lime productioil in Snow Hill in May 1936, production from the Cotton Valley formation in Schuler in 1937, and Smackover lime production from the Buckner field in November 1937. With this background and subsequent seismic work, which was carried on partly because the old shallow wells drilled in the township had shown evidence of closure in the Upper Cretaceous beds, the discovery well, Kerlyn Oil Company's Barnett No. I, Sec. 14, T. 17 S., R. 20 W., was originally projected to a total depth of 6300 ft., to test the equivalents of the Morgan sands of the Cotton Valley series, then producing at Schuler. The well was carried to a depth of 6325 It. and tested the objective beds without finding commercial production. In the meantime, however, one well had found production in the Jones sand and another in the Smaclrover lime at Schuler. Kerlyn immediately made arrangements to deepen the Barnett well to the Smackover lime. The top of the Smackover lime was encountered at 7618 ft. and the well

Jan 1, 1943

By Robert L. Braun, Arthur E. Lewis

A contained nuclear explosion is proposed to produce a chimney of broken ore well below the water table. After the chimney is filled with water and reaches hydrostatic equilibrium, oxygen, under pressure, is introduced near the bottom of the mass of broken rock. The increase in solubility of oxygen at high hydrostatic pressure is sufficient to initiate the oxidation of the primary sulfides, chalcopyrite and pyrite. The oxidation and dissolution of these sulfides produces enough heat to increase the temperature of the ore and water in the chimney as much as 100° to 150°C. The rate of dissolution of chalcopyrite exposed to oxygen-saturated solutions becomes so rapid under these conditions that the rate of copper extraction becomes limited by the accessibility of chalcopyrite to the solutions. Means of solution control and distribution of oxygen in the chimney have been examined in some detail. A calculational model utilizing experimentally determined solubility rates is utilized to estimate the temperature rise in the chimney and the rate of copper recovery as a function of initial temperature, sulfide content of ore, and size of ore particles. It is concluded that the high pressure and high temperature obtainable in a large ore mass broken by nuclear explosives promise the rapid and economic recovery of minerals not considered soluble by conventional in-situ leaching methods. The method should be broadly applicable to the kinds of deep deposits that must be depended on for future production and with minimum disruption of the environment.

Jan 1, 1974

By H. E. Cline, E. F. Koch, J. L. Walter

It has been postulated and, in a few instances shown, that some kind of dislocation structure will be present at semicoherent interfaces to accommodate small lattice mismatches. In the present study of the NiAl-Cr eutectic, regular arrays of interface dislocations are observed at the boundary between the chromium-rich rods and the NiAl-rich matrix. The networks were examined by transmission electron microscopy and selected area diffraction. The rods and the matrix have a crystallographic relationship in which all directions and planes of the two phases are parallel. The dislocation networks are cmposed of a<100> dislocations lying on the intersections of the cylinders with (100) planes. Dislocations forming hexagonal rather than square arrays are also observed at certain areas of the network. The morphology of the network is consistent with the interpretation of mismatch being accommodated by interface dislocations in the cylindrical geometry. The measured spacing between dislocations was used to calculate an apparent lattice mismatch between the phases (˜0.35 PCt)interface network energy (-140 ergs per sq cm), and network strengthening (-10,000 psi). It has been proposed by Frank and Van der Merwe1 that dislocations should be present at the boundary between two semicoherent crystallographically related phases. The role of the interface dislocations would be to reduce the internal stresses, caused by the mismatch in atomic spacing across the interface. Such dislocations have been observed at the interface between expitaxially grown films and Substrates.2-4 Interfacial dislocations have also been observed at precipitate-matrix interfaces.&apos;-&apos; Directionally solidified eutectics have been shown to have semicoherent phases1&apos; and would, therefore, be expected to have interfacial dislocations as found by Weatherly at a lamellar fault in A1-A12Cu.11 The NiAl-Cr eutectic appeared to be a promising system to examine because both phases are cubic, the lattice mismatch is small, and the phases are crys-tallographically related. Furthermore, the eutectic is easily thinned for transmission microscopy. Indeed, interfacial dislocations were observed and this report describes the nature of the dislocation networks in the boundary between the NiAl-rich ma-trix-phase and the fine chromium-rich rods.21 I) EXPERIMENTAL PROCEDURE Ingots, 3/4 in. in diam and 6 in. long were made by melting in vacuum and casting under argon using 99.9 pct pure material. The composition, in at. pct, was 33 pct Ni, 33 pct Al, and 34 pct Cr. The ingots were then placed in A1203 crucibles on a water-cooled base, melted by means of induction, and withdrawn from the hot zone at the rate of 1 in per hr under argon.* * T his material was first directionally solidified in this laboratory by E. R. Stover Slices were taken perpendicular to the growth direction of the directionally solidified ingot for metallography and for transmission electron microscopy. The electron transmission samples were thinned mechanically, then thinned electrolytically in A-2 electrolyte* *A-2 electrolyte: 62 ml perchloric acid, 700 ml ethanol, 100 ml butylcellosolve, 137 ml distilled H20. until a hole appeared in the foil. 11) EXPERIMENTAL RESULTS A) Optical Microscopy. The microstructure, viewed on a plane perpendicular to the growth direction, is shown in Fig. 1. The structure consists of cells or colonies of parallel chromium-rich rods in the NiAl matrix. The cells occur when there are impurities present12 or, in a ternary eutectic, if the composition is slightly off the eutectic composition. The axis of the chromium-rich rods is parallel to the growth direction except near the cell boundaries. Here the rods may assume angles to the growth direction; however, examination shows that the crystallographic relationship between the rod and the matrix remains the same. Fig. 1 includes cell boundaries where the rods formed at a large angle to the growth direction. The variation of rod position across the cells made it possible to Fig. 1-Structure on plane perpendicular to growth direction. Rods near cell walls are at large angle to growth direction. Magnification 315 times.

Jan 1, 1970

By John Chipman

RECENT developments in iron alloys containing nitrogen have indi-cated that this element may exert a considerable influence on the proper-ties of the metal. This influence is not always in an undesirable direction and the indications are that nitrogen should be regarded as an alloying element, the amount of which should be subject to control, rather than as an inherently deleterious impurity. In controlling this element in liquid iron to the best advantage, it is necessary to have a reliable background of fundamental data pertaining to solubilities, rates of solution and chemical reactions of nitrogen in liquid iron. Obviously, the first step in such an investigation is the determination of the solubility of nitrogen in pure iron, and this has been the object of the experiments described in this paper. The solubility of nitrogen in solid iron has been measured by Jurich,1 Sieverts,2 Martin,3 and Iwasé4 and the agreement among the first three inspires confidence in their results. No accurate determinations of its solubility in liquid iron have been recorded though several investigators have obtained approximate results. Strauss5 was able to introduce 0.03 to 0.04 per cent nitrogen into steel by the action of either ammonia or nitrogen on the liquid metal. This was accomplished by Eilender and

Jan 1, 1935

By S. J. Hardison

IN the fall of 1912, the appearance of water in the oil of the Nevada Petroleum Co., Coalinga, Cal., made necessary the installation of a dehydrating plant to reduce the water below the 3 per cent. limit prescribed by the agency. Unlike the mining industry, technical literature of the oil industry is limited and extremely unsatisfactory. Until the recent efforts of the Petroleum and Gas Committee of the American Institute of Mining Engineers, no concerted movement has been instituted to secure publication of papers dealing with the problems of the oil business, and because of the additional fact that dehydrating of oil has not been practiced in California to any extent up to comparatively recent time, it was found necessary to experiment in order to determine the most satisfactory plan for this purpose. It is easy to write regarding successful enterprises, but, while not so pleasant, it is equally desirable to write of failures so that others may be saved the loss incident to such investments. The water in this oil occurs both free and as an emulsion. Free water easily settles out, but the emulsion requires treatment. So far as can be determined, the emulsion consists of globules of water surrounded and enveloped by a film of, oil. Starting with this hypothesis, the theory has been evolved that in order to break up this emulsion the water must be heated at least to boiling point, when an explosion takes place destroying the globule. Unfortunately, this condition was not recognized in the installation of the first plant, which was planned on the following lines: A heater was arranged so that all the oil from the wells could be heated before reaching the shipping tanks, these being already fitted with coils for steam heating. Tanks were filled with about 4 ft. of water, live steam was turned into the coils and the water brought nearly to the boiling point, when the heated oil was run in. This for a time was partly successful, but the length of time necessary to apply this heat was too great for practical operating.

Jan 3, 1915

By T. M. Gurr

The United States is the world&apos;s leading producer of phosphate rock. In 1975 according to the US Bureau of Mines&apos; statistics, 44.3 million tonnes (48.8 million st) of phosphate rock were produced in the United States, l which is 40.6% of the world&apos;s production.2 The major phosphate producing areas of the United States are located in [Fig. 1] and the production for 1975 is listed as follows: [ ] All of these areas produce phosphate from deposits which are of marine sedimentary origin. Occurrences of phosphate exist throughout the United States in numerous locations that are of both igneous and sedimentary origins. However, these other phosphate occurrences vary greatly in extent and economic significance. Georgia, South Carolina, California, Texas, Arkansas, Kansas, Iowa, Alabama, Kentucky, and Virginia are but a few of the states in which phosphate is thought or known to exist. The near future expansion will probably continue to be in, or near, existing producing areas, (i.e., Florida and North Carolina).

Jan 1, 1980

By B. H. Caudle, B. M. Hickman, I. H. Silberberg

Secondary recovery projects often are not started in oil reservoirs until dictated by rising GOR&apos;s or declining oil production. Such circumstances require a well dispersed injection pattern to prevent the oil bank from bypassing the production wells. Many times this purpose is served by using the five-spot or line-drive patterns, in which half of the wells are made injection wells. A regular injection pattern is proposed that is based on the same well spacing as the five-spot but in which only a third of the wells need be converted to injection wells. Fluid flow model studies on this proposed pattern show that production histories will be as good as those for a five-spot pattern at mobility ratios of three and above. The model data are presented in a form that may be used to predict recoveries from both homogeneous and stratified formations. Introduction The injection of fluid into a petroleum reservoir usually is prompted by an actual, or predicted, loss in the productivity of the reservoir. Often, an oil reservoir is produced by pressure depletion until high GOR&apos;s dictate a change in policy. Fluid injection also causes increased ultimate recovery, but this usually is of less importance to the operator than is the maintenance of the production rate. It is a fact that the ultimate recovery in any particular fluid injection project is relatively independent of the number and spacing of the injection wells as long as the reservoir voidage through the production wells is balanced by the total injection rate. However, the response of a production well is directly affected by the distance it lies from an injection well. In places where the well productivities are declining, the injection wells should be spaced as evenly as possible among the producing wells ("dispersed" injection pattern). More particularly, if the production response depends upon the formation (and subsequent production) of an oil bank, each production well should be surrounded by injection wells. Otherwise, the oil productivity will increase very little as the oil bank moves past the well.&apos;.&apos; An evenly spaced injection pattern has the best chance of generating an oil kick in the production wells. If reservoir voidage and injection rates are to be equal, the ratio of injection wells to production wells must be equal to the ratio of the average injectivity to the average productivity (in reservoir volumes). This ratio is in strumental in choosing the injection pattern. Table 1 shows the production well to injection well ratio for the dispersed injection patterns that have been described in the literature.&apos;-&apos; All of these patterns will have comparable recoveries and response times (for the same basic distance between wells). The choice of pattern there fore depends upon the relative injectivity and productivity of the wells and upon the type of drilling pattern employed. Another important factor may be the ability of the proposed production wells to make up the lost productivity from those wells converted to injectors. These factors become more pronounced at the higher oil viscosities (low gravity oils). All other things being equal, the probable ratio of single well injectivity to single well productivity will be equal to the water-oil mobility ratio of the proposed flood. Thus, high mobility ratios (due to low gravity oil) should call for fewer injection wells — as long as these injection wells are "dispersed" to obtain more even pro duction response for the remaining wells. Secondary re covery projects in oil reservoirs seldom, if ever, will have mobility ratios requiring more injection wells than production wells. Thus, only the last five of the patterns listed in Table 1 will be of significant interest in oil recovery. Almost every development drilling program calls for the wells to be drilled along equally spaced rows and

Jan 1, 1969

By L. A. Panek

When rock is subjected to a load it is deformed. Ordinarily this is observed in a mine as the displacement of one point with respect to another-the deflection of the roof, which may be observed as a convergence between roof and floor; or the extrusion of material from the rib, which may be observed as a decrease of the distance between the rib and the post of a timber set. The effect of excessive pressure may be a rockburst if the rock is strong, or it may be "squeezing" ground if the rock is "soft". Some desirable effects of high stress (high in relation to strength) are the caving of roof in a longwall mining operation, the caving of ore in block caving, and the decrease in mechanical energy required to break down the mineral seam in a retreating pillar-robbing operation. In any case, whether the observable effect of rock load is desirable or undesirable, it is a displacement, and depends on the following four factors:

Jan 3, 1961

By Howard Scott

INVAR is the preeminent low-expansion metal by virtue of the fact that it can be prepared with a zero coefficient of expansion at atmospheric temperature. This fact suggests that there is little room for improvement in the expansion properties of the low-expansion nickel steels. The inference is true, however, only so far as the expansion at and near atmospheric temperature is concerned, because the expansivity of invar starts to increase rapidly on heating above 100° C. and soon reaches the value of copper. Guillaume1 met this situation by increasing the nickel content above that of invar. By that expedient, alloys having low expansivity under higher temperatures were obtained, but not without a large increase in minimum expansivity. The increase in minimum expansivity with increasing nickel content severely limits the technical applications of these alloys at high temperatures. Prospects of improving the expansion characteristics of the nickel steels is offered by alloying. Search for an advantageous alloying addition by analogy with other alloy systems, however, is not productive because the low-expansion characteristic is unique with that system. The rule of mixtures usually gives a fair value of the expansivity of other solid-solution alloys, but in the iron-nickel systems gives a value of 18 X 10-6 per deg. C. whereas the actual value is 1 X 10-6 per deg. C. Apparently suitable additions are not to be deduced from such ingenuous considerations. Recognition of the fact that the temperature range of low expansivity in nickel steels is terminated with loss of magnetism affords a more promising basis for the selection of an advantageous element. One may expect from that fact that additions of nonmagnetic elements to the iron-nickel alloys are detrimental to the low-expansion characteristic. Indeed, carbon, manganese, silicon, copper and chromium are detri-mental to the expansion properties and no nonmagnetic element is reported to be beneficial. From the same viewpoint, the addition of a magnetic metal offers prospects of improvement. As two of the three ferromagnetic elements are already present in the

Jan 1, 1930

By Frank L. Gaddy

Falls of roof account for over 50% of the fatalities that occur in coal mines in the US. Thus, roof control is one of the more important phases of underground mining. In reality, the control of roof influences the system of mining and is a major determinant of the width and spacing of working places, operations at the mining face, ventilation control, and surface subsidence. Frequently, the control of roof is the largest single cost item. Roof control is a never-ending task, not only at the working face and throughout sections where men are working, but along haulways and air- ways that must be maintained for the life of the mine. This is because roof, even the hest of roof, slowly deteriorates, so it must be frequently examined, with corrective support applied when needed. As coal is excavated, stresses are set up in the roof because the previous equilibrium is upset, resulting in pressures that cause fractures and slight movements that are frequently hard to detect. Unless the immediate roof, in the excavated area, is given support by artificial means, it might fall or there might be a succession of falls, varying from a thin scale to several feet, depending on the nature of the top. Exceptions to this are those rare mines, or sections of mines, with hard, strong, nonweathering roof that requires no support. GENERAL CLASSIFICATION OF ROOF There are two broad types of roof as far as support is concerned: the immediate roof above the coal and the main roof. Artificial support for mining purposes is only concerned with the immediate roof as nothing except large blocks of solid coal, or massive concrete, will support the main roof. The immediate roof is generally a few feet thick but call vary from inches to 6.1 m (20 ft) or more. There are examples of where there is no imrncdiate roof as the massive main roof lies directly on the coal

Jan 1, 1981