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"No true conception of the Park City mining district can be obtained without first giving consideration to the part it has played as a consistent producer of mineral wealth. Its position in this regard is almost unique in the annals of a lead silver camp. For over fifty years it has been a continuous producer of lead and silver and for twenty years it has added to the world's supply of zinc. Few camps with its productive history are so little known to the mining fraternity for the reason that its life has never been punctuated by periods of ""boom"" which serve to attract general attention, neither has it been the field of operation for promoters who temporarily focus attention upon their scene of action. Its history is one of legitimate mining operations. These were at first carried on by a number of smaller companies. A period of consolidation followed and at the present time the entire production of the camp is in the hands of two major companies and one smaller company. These are flanked by a number of prospecting properties, which are at this time actively engaged in the search for ores and later events will doubtless put some of them in the producing class.A technical discussion of the ore occurrence and mining operations in the camp will be the subject of a paper to be read before this meeting of the Institute. The mission of this article is to supply a ""Baedeker"" where Baedeker is lacking.The town of Park City is a typical, up-to-date, western mining camp which owes its existence as a town of 4,500 inhabitants solely to the mining industry. The camp is located 7,000 feet above sea level, thirty-two miles east of Salt Lake City. It is situated on the Victory Highway seven miles from its junction with the Lincoln Highway and has the benefit of excellent automobile communication with the metropolis of the state. Both the Denver and Rio Grande and the Union Pacific Railroads give daily train service to the camp and effectively solve the transportation problems of the mining companies."

Jan 1, 1925

By E. W. Pehrson, J. W. Furness

THE five charts presented here- with are part of an original group prepared by the U. S. Bureau of Mines showing the international trade in the principal metals and metallic ores. Charts 011 anti- mony, chromite, copper, lead, manganese, mercury, nickel, tin, tungsten, and zinc were published in the February, 1936, issue of the Engineering and Mining Journal. Those shown here include bauxite, aluminum, iron ore, pig iron, and the platinum-group metals.

Jan 1, 1936

By M. Deighton, R. N. Parkins

The metals Cd, ,Wg-, Sn, TI, Zn, and Zr reach a peak hardness after a criticfir1 deformation by rolling- and then soften with fwther rolling-, thereby exhibiting wovk softening. Optical metallography on Cd, Mg, and Zn shows that work softening is accompanied by a change in grain size occurring during deformation. The creep of zinc from -1l° to +60°C at stresses in the range of 7.9 to 17.3 kg per sq mm is given by € = e0 -t- Bt + Kt +at6. The third and second rate constcints are related by the equation a = K~ K6 and their stress and temperature dependence can be represented by the equations K = A, . exp - (u, - Bu)/kT. A model based upon the stress activated glide of sub-boundaries is proposed which qualitatively accounts for the metallog-raphic observations. Expressions, which are in reasonable quantitative agreement with the ex-pe~inzental observations, are derived for the creep of zinc. THE term "work softening" has been used previously by Polakowski1 and by Cottrell and stokes2 to describe phenomena where further strain of a deformed material leads to a decrease in flow stress. In both cases, however, the conditions were changed for the second straining. Here, the term "work softening" is intended to refer to a decrease in flow stress after continued straining in the same direction at the same temperature: work softening is the antithesis of "work hardening". Work softening of zinc was reported by chadwick3 and in discussion of that paper Jenkins4 indicated that cadmium also work softens. More recently work softening has been reported5 in two magnesium alloys, -99.5 pct Mg. Chadwick found that the hardness, 0.2 pct Proof Stress and the UTS of electrolytic zinc all increased with progressive cold reductions up to 30 pct and then progressively decreased with further rolling. Gay and Kelly6 used a back-reflection X-ray technique to study the effect of cold rolling zinc and found that although deformations greater than 2 to 5 pct reduction in thickness produced some recrystallized grains, deformations greater than 40 pct caused com-plete spontaneous recrystallization. At deformations greater than 60 pct the material was found to consist solely of recrystallized grains, -20 pm diam, the size of which decreased with increasing reduction and was much less than the initial grain size of the annealed material (-300 pm diam). Similar results were also reported for cadmium, tin, and lead.6 Gay, Hirsch, and Kelly' suggest that these experiments indicate recrys-tallization takes place when the dislocation density exceeds a certain value. However, no measurements of MATERIALS AND EXPERIMENTAL PROCEDURE The purity of the metals used in this work is indicated by the following figures: Zn (99.99); Cd (99.94); Mg (99.95); T1 (99.99). The zirconium was iodide crys tal bar with a probable purity of about 98 pct. The metals were obtained in the form of 0.25 in. thick strip or 0.425 in. diam rod by various fabrication methods and then annealed to ensure complete re-crystallization. Hardness-deformation curves were obtained at room temperature by rolling 4 in. thick strip under conditions which left a surface adequate for diamond pyramid hardness tests immediately after rolling. The hardness was taken as the niean of five impressions made using a 5 kg load and the time elapsing between rolling and making the last impression never exceeded 5 min. The zinc specimens for creep testing were from 3 by 3 by 4 in. cast slabs which were rolled to 0.10 in. thickness starting at 350°C and finishing cold. The resulting strip was cut into pieces 1 in. wide and annealed in batches. With suitable choices of annealing temperature between 100" arid 400°C five different grain sizes varying from 4.54 x 10' to 3.03 x l05 grains per sq cm (530 to 20 um diam) were obtained. Creep tests were done in compression using a sub-press, based on a design after Ford,8 in which the strip is compressed between dies 0.100 in. wide under conditions of plane strain. Since there is no lateral spread of the material, the area of contact between the dies and strip remains constant throughout the test and the application of a constant load, using the load maintaining device of a hydraulic testing machine, resulted in a constant stress. Covering the dies with strips of P.T.F.E. reduced frictional effects to a minimum. The creep strain was obtained by measuring the travel of the crosshead of the testing machine to a sensitivity of 0.1 pct reduction in thickness. The complete subpress assembly was contained in a steel box and for tests above the ambient this was filled with liquid paraffin and heated electrically. Temperatures below the ambient were obtained with a cooling mixture of acetone and solid carbon dioxide in the box. The liquids were stirred and the temperature of the specimen, which was controlled to ±0.5"C dur-ing a test, was measured by a thermocouple placed near the dies. Compression testing of cylindrical specimens was also carried out in the subpress using hardened flat discs separated from the test material by P.T.F.E. sheets which obviated barrelling of the specimens. Various initial strain rates were supplied by the hydraulic testing machine, and the deformation was measured by a clock dial gage resting on the cross-

Jan 1, 1970

By E. W. Davis

The: mysterious Lake Erie price for iron ore, established each spring, determines the maximum price that will be paid during the following season for ore of Mesabi Non-Bessemer base grade. This price is important to the ore producers, hut since most of the ore in the Lake Superior district is owned or controlled by consuming interests, the really important question to them is not the price of ore but how much it will cost them to mine and transport their season's requirements to their furnace plants. However, a few million tons are actually sold each year, and considerable quantities are traded for mixing purposes, and the negotiations lor these sales and trades usually begin with some reference to the Lake Erie price. There is no difficulty with the Lake Erie price itself or with the manner in which it is established, but the system prescribed for determining the values of ores that are not exactly base grade is incomplete. The Lake Erie price takes into consideration only the iron and phosphorus contained in the ore, but when the ore producer is negotiating a sale or trade, he is confronted by the fact that his ore must he studied and the price adjusted, not only on the basis of the iron and phosphorus analyses, as specified by the Lake Erie price, but also on the basis of silica! alumina, manganese, structure, etc. The vague and unsatisfactory methods used in making these adjustments bear some relation to the manner in which the ore is supposed to act in the blast furnace. The ore producer may not understand all of the idiosyncrasies of the blast furnace, but if the smelting-plant operators have a system more accurate than the Lake Erie price method for determining the relative values of different ores, why not pass this information on to the ore producers, so that they can make use of it and perhaps modify their practice in such a manner as to benefit both themselves and their customers? There is a lack of understanding and appreciation between these two groups that may, to some extent, be unavoidable, but in the interests of efficiency and conservation rules that are more accurate and complete than the Lake Erie price method in use at the present time should be established for the guidance of the ore producers. Recently a paper was read before the Eastern States Blast Furnace and Coke Oven Association, by Mr. G. W. Hewitt, Manager Production, Blast Furnace and Coke Oven Department, Wheeling Steel Corporation, in which he explained how his company determines the relative values of different grades of Non-Bessemer ore. This is a very important paper, perhaps not so much on account of the actual calculation methods described as because of the fact that premiums and penalties are shown on Non-Bessemer ores for silica, alumina, phosphorus, and manganese. As pointed out by Mr. Hewitt, the premium and penalty system described may not apply without adjustments to other smelting plants. However, if the various ore

Jan 1, 1941

By Albert Wiggin

THE copper-bearing sulphide ores from the mines in Butte, Mont., which are for the most part concentrated at the Boston & Montana duction Works in Great Falls and at the Washoe Reduction Works in Anaconda, contain the following minerals of economic value: Chalcocite, Cu2S; enargite, Cu3AsS4; cupriferous pyrite; bornite, Cu3FeS3; covellite, CUS; tetrahedrite, 4 CuS2Sb2S3; and tennantite, Cu8AsS7;. All of the ores carry a high percentage of pyrite. Many of the above sulphides are argentiferous and also carry from 10 to 20 cts. per ton in gold. The gangue is quartz and highly altered granite, with sphalerite and galena and more rarely barite and hubnerite as accessory minerals. An average chemical analysis of the second-class ore concentrated at Great Falls and Anaconda would be as follows: Copper 3.2 to 3.4 per cent. Silver 2. 3 to 3.0 oz. per ton. Gold 0.0-1 to 0.15 oz. per ton. Si02.. 55 to 60 per cent. FeO 12 to 15 per cent.. Sulphur 12 to 1.5 per cent. Al2O3, S to 10 per cent. CaO 0.5 to 0.8 percent. As203, 0.5 to 0.6 percent. Lead 0.2 to 0.3 percent. Before describing the Great Falls flow sleet as installed, at Anaconda, a brief history of the Great Falls concentrator will be given, including a description of the various concentrating machines and systems which have been tested in the search for a flow sheet which would give a higher recovery of copper.

Jan 8, 1913

By C. D. Ramsden

DURING the war years of 1941 to 1945, maintenance of mine locomotives and other mine equipment took the form of rebuilding rather than of renewing. Pur¬chase of new parts became increasingly difficult and mine operators found it necessary to maintain equipment by sal¬vaging old parts. Mine-locomotive wheels, although not representing a high cost per pound of material, contain a con¬siderable amount of steel and without rebuilding would have to be scrapped long before even a moderate percentage of the steel in the wheel is actually consumed. Many mine operators have been re¬building locomotive wheels for several years with automatic open arc-welding equipment. In 1927, the Pittsburgh Coal Co. started such a program, using a single Westinghouse automatic welding head. Since that time, many refinements have been added, until in 1944 the setup was operating very efficiently. A desire to increase wheel life and to hold down rising costs led the company in 1944 to investigate the possibilities of the under¬flux arc-welding process for wheel rebuild¬ing, although at that time, little or no work had been done on multiple pass or "build-up" welding with the underflux arc. Work with this process had been confined largely to welding together flat plates in a "down hand" position. Possibilities for savings were intensified by the fact that the company has 300 locomotives in operation, using actively or as spares 1200 sets of wheels. During 1942 and 1943, about 500 sets of wheels were sent each year to the company's maintenance shop at Library, Pa., for rebuilding. Based on having 800 sets in service (many of the company's heavy locomotives have three- sets of trucks), the average life of a set of wheels was approximately 19 months. Anything that could be done to increase wheel life promised sizable annual savings. OPEN ARC WELDING With the open arc process, a set of wheels could be rebuilt for about 40 pct of the cost of new wheels. Underflux arc welding gave promise of greatly increased welding speeds, more homogeneous, dense deposits and the chance for use of a wider range in welding-wire compositions. Against this was ranged the higher cost of materials and the cost of developing the process from the theory to a practical reality. Since 1927, when a single open arc head was placed in operation, fixed welding procedures had been gradually developed, a positioner for handling a set of wheels was built, and a second head was placed in operation in order to weld two wheels simultaneously. The fixture, or posi¬tioner, which was built to position and turn the wheels under the two welding heads, included a motor drive, controlled by a rheostat, which rotated the wheels through a double set of speed reducers and a removable jaw coupling attached to one end of the axle of the wheel truck.

Jan 1, 1946

By E. W. Davis

The: mysterious Lake Erie price for iron ore, established each spring, determines the maximum price that will be paid during the following season for ore of Mesabi Non-Bessemer base grade. This price is important to the ore producers, hut since most of the ore in the Lake Superior district is owned or controlled by consuming interests, the really important question to them is not the price of ore but how much it will cost them to mine and transport their season's requirements to their furnace plants. However, a few million tons are actually sold each year, and considerable quantities are traded for mixing purposes, and the negotiations lor these sales and trades usually begin with some reference to the Lake Erie price. There is no difficulty with the Lake Erie price itself or with the manner in which it is established, but the system prescribed for determining the values of ores that are not exactly base grade is incomplete. The Lake Erie price takes into consideration only the iron and phosphorus contained in the ore, but when the ore producer is negotiating a sale or trade, he is confronted by the fact that his ore must he studied and the price adjusted, not only on the basis of the iron and phosphorus analyses, as specified by the Lake Erie price, but also on the basis of silica! alumina, manganese, structure, etc. The vague and unsatisfactory methods used in making these adjustments bear some relation to the manner in which the ore is supposed to act in the blast furnace. The ore producer may not understand all of the idiosyncrasies of the blast furnace, but if the smelting-plant operators have a system more accurate than the Lake Erie price method for determining the relative values of different ores, why not pass this information on to the ore producers, so that they can make use of it and perhaps modify their practice in such a manner as to benefit both themselves and their customers? There is a lack of understanding and appreciation between these two groups that may, to some extent, be unavoidable, but in the interests of efficiency and conservation rules that are more accurate and complete than the Lake Erie price method in use at the present time should be established for the guidance of the ore producers. Recently a paper was read before the Eastern States Blast Furnace and Coke Oven Association, by Mr. G. W. Hewitt, Manager Production, Blast Furnace and Coke Oven Department, Wheeling Steel Corporation, in which he explained how his company determines the relative values of different grades of Non-Bessemer ore. This is a very important paper, perhaps not so much on account of the actual calculation methods described as because of the fact that premiums and penalties are shown on Non-Bessemer ores for silica, alumina, phosphorus, and manganese. As pointed out by Mr. Hewitt, the premium and penalty system described may not apply without adjustments to other smelting plants. However, if the various ore

Jan 1, 1941

By F. W. SUTTER

IN order to have ore available on the completion of the beneficiation plant at Clifton and to provide for continuous production while underground development was carried out, it was decided to develop an open-pit through the crest of a long hill in which the ore outcropped, using 40-ft. vertical benches.

Jan 1, 1943

Arizona F. P. MATHEWSON, Chairman F. W. MACLENNAN, First Vice-chairman _CLYDE F. WEED, Second Vice-chairman F. D. GARDNER, Secretary-Treasurer Box 4097, University Station, Tucson, Ariz. ARTHUR CROWFOOT G. H. DOWELL HENRY F. FASTER R. D. LEISK Boston Meets first Monday each month, October to May, inclusive FREDERICK K. MORRIS, Chairman DANIEL CUSHING, Vice-chairman F. LEROY FOSTER, Secretary-Treasurer Rooms 6-202, Mass. Inst. of Tech., Cambridge, Mass. WILLIAM H. COBURN RUSSELL 01550K

Jan 1, 1934

By E. S. Wheeler, M. W. Murphy

A LARGE part of the molybdenum produced in Colorado is converted and consumed in the Eastern States. As the raw materials and the power needed for the conversion of the Colorado concentrate are also accessible in the Eastern States, the conversion plant has been installed some 1500 miles east of where the ore is mined and milled. When concentrate was first produced at Climax in 1918, a custom smelter converted the product into ferromolybdenum. By 1924, the Company had decided to produce calcium molybdate and rented a building and installed equipment for that purpose at Langeloth, near Burgettstown, Pa., about thirty miles west of Pittsburgh. For the first few years the plant was a simple one of small capacity. A small hand-rabbled roaster was used, the product of which was made iota calcium molybdate by a conventional method; then an eight hearth mechanically rabbled roaster was installed to increase and speed up production. The output was considerably less than a million pounds of contained molybdenum annually until 1928, when a small part of the produc-

Jan 1, 1946

Payloader The Frank G. Hough Co. has made available another four-wheel drive tractor-shovel. It has a 1 cu-yd bucket with 60 hp Diesel or 54 hp gasoline power optional. The use of large pneumatic tires, same size all around, and drive on all four wheels gives this new Payloader traction to work effectively in sand, mud and snow, and travel on pavements with- [ ] out injuring the surface. Rear wheel steer with power booster plus short wheel base makes it easy to operate and highly maneuverable. Four speeds in both directions insure fast travel speeds for transport and fast operating speeds on shuttle loading or similar operations. Bulldozer blade, crane hook, fork lift and snow plow attachments are available, quickly interchangeable with the bucket to further increase its multi-purpose usefulness. Circle No. 1

Jan 1, 1952

By H. H. Evinger, M. Muskat

Although the shooting of oil wells for the purpose of increasing production has been practiced since 1866, present-day shooting technique has been arrived at almost wholly by a process of trial and error. The difficulties attending either a theoretical analysis of the problem or an experimental attack become apparent when one actually embarks on a theoretical investigation or attempts to formulate an intelligent experimental program. The literature on the subject consists mainly of descriptions of current practice, scattered eye-witness accounts of events following the shooting of a well, and vague speculations on the mechanical processes involved. In contrast to quarry blasting, the results of oil-well shooting cannot be determined by means of visual inspection, and it is perhaps for this reason that only one attempt at what approaches a direct experimental attack has been reported in the literature.' In these experiments, charges of liquid nitroglycerin were exploded in holes drilled in a sandstone outcrop. In order to observe the character and extent of the resulting fractures, the rock was blasted away so as to expose the original shot holes. After all this had been done it was found impossible to distinguish the fracturing due to the original shots from that due to the subsequent blasting. The enlargement of the holes due to the pulverizing action of the shots was measured and an attempt was made to determine the effectiveness if sand tamping. Only five shots were made and few definite conclusions could be drawn. Some small-scale experiments to deter-mine the effect of tamping were performed by Snelling and IIalL2 Small charges (zo grams) of dynamite were detonated at the bottom of a cylindrical hole in a lead block and the resulting enlargement of the hole was taken as a measure of the effectiveness of the explosion. It was found that when the shot was tamped with a sufficient amount of sand or clay, the volume enlargement was approximately double that found when no stemming had been used. The properties of the explosives have been the subject of much study by the manufacturers, the U. S. Bureau of Mines, and various other agencies. For example, velocities of detonation for many commercial explosives are to be found in the Blasters' Handbook, issued by the Du Pont company. Many other properties are given in a treatise on the subject by Naoum.~ The shock wave that accompanies the detonation of high explosives has been studied photographically by Payman4 and others. The hydrodynamical theory of the shock wave has received much attention, and an extended theoretical treatment is given by Bateman.6 Two aspects of the well-shooting problem will be considered in this paper; namely, the fracturing of subsurface strata, and possible damage to casing. With respect to the former of these, several calculations have been made giving the stresses in the rocks surrounding the shot. In order to arrive at numerical results at all, however, it is necessary to introduce a great many simplifying

Jan 1, 1941

By C. J. Rosa, W. C. Hagel

An attempt is made to determine the diffusion coefficients of oxygen ions in hypostoichiometric zirconium oxide. A phenomenological theory is developed for three-phase, unidirectional volume diffusion of a gaseous species from a planar source. Knowledge about oxygen diffusion in a and ß zirconium and experimentally measured rates of movements of interfaces permit the evaluation of oxygen ion diffusivi-ties in ZrO2-x. The results conform to the relationship: sq cm per sec, for the temperature range of 875" to 1050° C. DIFFUSION coefficients of oxygen ions in stoichio-metric oxides have been studied by many investigators. The obtained results not only supplement the knowledge about the lattice-defect structures of oxides and conduction mechanisms but also provide information of technological importance. Rate processes such as oxide sintering, high-temperature creep deformation, and oxidation of metals and their alloys are directly dependent on diffusion phenomena. Unfortunately, diffusion coefficients obtained from studies on stoichio-metric oxides cannot be treated without restraints when applied to oxidation kinetics, if precise evaluations of oxidation rates are desired. Oxides formed on metals are usually nonstoichiometric and exhibit nonuniform distribution of either cation or anion vacancies across their thicknesses. Debuigne and Lehr1 extended Danckwerts'2 mathematical analyses and furnished a semitheoretical treatment for evaluating oxygen diffusion coefficients in zirconium oxide in terms of weight gain measurements during oxidation of zirconium in the temperature range 400° to 850°C. Their calculations are based on theoretical partitioning3 of the total amount of oxygen between a zirconium and its oxide phase. An inherent discrepancy appears to continue throughout their calculations. The amount of oxygen confined to the oxide phase should be corrected by multiplying the calculated oxide thickness by the inverse of Pilling-Bedworth ratio, if expansion of zirconium dioxide is taken into account. The purpose of the present investigation is to provide a new semitheoretical treatment for evaluating diffusion coefficients of moving species in hypostoichiometric oxide. The analyses are relevant to unidirectional volume diffusion. Although the presented method is quite general, its applicability will be discussed in terms of kinetic measurements from oxidation of zirconium at temperatures above the a/ß transition, for reasons stated in the later part of this paper. EXPERIMENTAL Pure, 99.93 wt pct, zirconium samples of approximately 2 by 1 by 0.35 cm were exposed to oxygen for various times at four temperature levels: 875°, 950°, 1000°, and 1050°C. High-purity, better than 99.9 vol pct oxygen was passed through a cold trap and columns containing anhydrous CaSO4 to remove residual water vapor. Before exposing to oxygen at a pressure of 500 Torr, specimens were subjected to wet abrasion on 200- through 600-grit Sic papers and polished with 1—p diamond dust. Prior to oxidizing, all zirconium samples were vacuum-annealed at 10-6 mm Hg for about 15 min at the test temperature. The temperature variation across the uniform heat zone was ±2°C from the preset value. Final polishing, for phase thicknesses measurements, was performed by using 8- and 1-p diamond dust and followed by vibrator polishing with 0.05-µ ? Al2O3 solution. Measurements of phase thicknesses were made by projection on a metallographic viewing screen. Conventional powder X-ray analyses for the oxide were employed. RESULTS Fig. 1 is an example of the cross section of oxidized zirconium. Designations of phases given below this figure are the same as those used in the three-phase diffusion system represented by Fig. 5 in the following section. Zirconium oxidized for longer exposure times showed two types of oxides: white oxide at the surface and an underlaying layer of gray oxide. X-ray powder patterns of these oxides at room tern-

Jan 1, 1969

By W. B. Wise, H. D. Attra, W. M. Black

The purpose of this paper is to illustrate a comparatively new approach for solving a problem that has plagued oil producers for many years—how to make the most money with available field production capacity. In a very basic operation such as a top-allowable one-well field, a computer and staff of engineers are not required to determine that the best operation is to produce that well at its maximum for as long a time as it will produce. However, as the problem becomes more complex and the number of wells and number of reservoirs increase, it probably will be a wise choice to devote some engineering thought and calculation time to determine the best way to operate that field on both an ultimate and day-to-day basis. Continued developments in the field broadly referred to as "operations research" have led to a number of useful engineering analyses for optimizing field operational problems. One of these techniques, termed linear programing, is parlicularly interesting because of its potential applications to the study of complex oilfield operating problems. Linear programing is concerned with the problem of planning a complex set of interde~endenl activities in the best possible (optimal) fashion. A field application of linear programing is being used to maximize daily income from a multi-reservoir producing operation. The initial results of this study indicate that the linear programing technique (I) can be applied effectively to field problems, (2) can be used to detect unsuspected avenues for improving operations and (3) can effect a significantly improved means of controlling field operations through the use of the highspeed computer. INTRODUCTION The usual approach for studying complex field operational problems has been to look in detail at several basic plans suggested by judgement and experience and, then, to choose the best plan from those investigated. This approach is entirely satisfactory provided: (1) that judgment and experience alone will reliably pick the best or near the best program as one of the plans to be investigated; and (2), and most important, that the factors which control field production will not change. This paper deals with the large group of field operations which are at least one-step removed from a satisfactory solution using the conventional method of analysis. Problems such as pipeline- and gathering-system design, transportation studies, large field development projects and multi-reservoir producing operations fall in this latter category. To find the best program for handling these problems when the best program is not obvious, a complete optimization study is required, and high-speed computers are required to continually update the program once it is selected. Operations of this type have an extremely large number of possible solutions. However, only one will result in maximum economic return and, more important, this one program must be re-evaluated and adjusted constantly to accomodate such changing field factors as the number of producing days, the price of crude, the discovery of new reserves, declining reservoir pressure with subsequent decline in production and a host of other factors which characterize specific operations. One of the most widely used, direct methods of optimization is a numerical procedure termed "linear programing", which is designed to investigate systematically each of the possible solutions involved in a given problem, determining rapidly and uniquely the optimum answer. As implied by the name, linear programing requires that all field variables be either defined or expressed in a series of interdependent linear equalities or inequalities. These relationships are solved simultaneously, using a form of matrix solutions to determine the optimum values for each producing variable that will maximize net profits. The solution techniques used in a recent field case study is termed the "simplex method" and is discussed in full detail in Ref. 1.

By M. Muskat, H. H. Evinger

Although the shooting of oil wells for the purpose of increasing production has been practiced since 1866, present-day shooting technique has been arrived at almost wholly by a process of trial and error. The difficulties attending either a theoretical analysis of the problem or an experimental attack become apparent when one actually embarks on a theoretical investigation or attempts to formulate an intelligent experimental program. The literature on the subject consists mainly of descriptions of current practice, scattered eye-witness accounts of events following the shooting of a well, and vague speculations on the mechanical processes involved. In contrast to quarry blasting, the results of oil-well shooting cannot be determined by means of visual inspection, and it is perhaps for this reason that only one attempt at what approaches a direct experimental attack has been reported in the literature.' In these experiments, charges of liquid nitroglycerin were exploded in holes drilled in a sandstone outcrop. In order to observe the character and extent of the resulting fractures, the rock was blasted away so as to expose the original shot holes. After all this had been done it was found impossible to distinguish the fracturing due to the original shots from that due to the subsequent blasting. The enlargement of the holes due to the pulverizing action of the shots was measured and an attempt was made to determine the effectiveness if sand tamping. Only five shots were made and few definite conclusions could be drawn. Some small-scale experiments to deter-mine the effect of tamping were performed by Snelling and IIalL2 Small charges (zo grams) of dynamite were detonated at the bottom of a cylindrical hole in a lead block and the resulting enlargement of the hole was taken as a measure of the effectiveness of the explosion. It was found that when the shot was tamped with a sufficient amount of sand or clay, the volume enlargement was approximately double that found when no stemming had been used. The properties of the explosives have been the subject of much study by the manufacturers, the U. S. Bureau of Mines, and various other agencies. For example, velocities of detonation for many commercial explosives are to be found in the Blasters' Handbook, issued by the Du Pont company. Many other properties are given in a treatise on the subject by Naoum.~ The shock wave that accompanies the detonation of high explosives has been studied photographically by Payman4 and others. The hydrodynamical theory of the shock wave has received much attention, and an extended theoretical treatment is given by Bateman.6 Two aspects of the well-shooting problem will be considered in this paper; namely, the fracturing of subsurface strata, and possible damage to casing. With respect to the former of these, several calculations have been made giving the stresses in the rocks surrounding the shot. In order to arrive at numerical results at all, however, it is necessary to introduce a great many simplifying

Jan 1, 1941

By Frank J. Markewicz, William Lodding

Greensand, greensand marl, and green earth are names given to sediments rich in the bluish green to greenish black mineral known as glauconite by the mineralogist. The word glauconite is from the Greek word glaukos, meaning bluish green. The term "greensand" as a rock name for a glauconite-bearing sediment is more appropriate than "greensand marl," a term that has been doggedly perpetuated in the literature. Because of its potash and phosphate content, greensand was dug and marketed as a fertilizer and soil conditioner for more than 100 years. The advent of prepared fertilizers with adjustable nutrient ratios led to the decline of green- sand for agricultural application. The material has since been recognized for use in water treatment. Unfortunately, in spite of large reserves and worldwide distribution, the mineral has not been utilized to any significant commercial extent because no major application has been found for a substance with its chemical composition and properties. This lack is probably due to a paucity of research on its potential commercial application. Extraction of potash received considerable attention during and just after World War I. Because of relatively high extraction costs and generally low potash content (up to 8%), glauconite lost its appeal as a source of this commodity. Historical Background Greensand was used as a fertilizer in New Jersey in the latter part of the 1700s. During the early 1800s its use became more common; applications of up to 100 tons per acre were sometimes made, although recommendations for agricultural use suggested 20 to 50 tons per acre (Tedrow, 1957). Many crops, especially the forage type, were said to improve with greensand application; however, because of slow release of potash, large quantities were required. Certain greensands that contain sulfur and sulfide minerals are harmful to plant growth, and these were classified as "poison," "burning," or "black marls." The availability of higher-grade potash salts from other mineral sources, and the manufacture of prepared fertilizers, displaced the agricultural use of green- sand during the later 1800s. During the mid-1800s the domestic greensand industry, centered in a small section of the eastern United States, grossed more than $500,000 per year. Toward the end of the century, annual production had dwindled to less than $100,000. By 1910 there were only six or eight greensand producers, grossing less than $5000 (Tyler, 1934). There was a small revival in the industry during World War I because of the curtailment of foreign potash, especially from Germany. During the later 1940s and early 1950s greensand was again recommended as a food nutrient for plants and farm crops. Agronomic studies discussed its potential as a soil additive that gradually releases potash and many trace- element nutrients essential for plant growth (Tedrow, 1957). Greensand was sold with the idea that it would condition soil and absorb and hold water while its base-exchange properties would release trace elements. For a short time glauconite was utilized in certain parts of New Jersey as a binding additive in the brick industry, and in the 1800s for making green glass (Cook, 1868). In the early 1900s the base-exchange property of glauconite was recognized for water treatment, and the mineral gained acceptance as a water softener. Mansfield ( 1922) does not mention base-exchange; however, the base ex-

Jan 1, 1975

By John Fritz

THE John Fritz Medal was presented to Ambrose Swasey of Cleveland, Ohio, in the Auditorium of the Engineering Societies Building, in New York, on April 23. Charles F. Rand, Chairman of the Board of Award, presided and, after speaking very briefly of Mr. Swasey, whose friend he has been for a great many years, ,introduced Gen. William Crozier, formerly Chief of Ordnance, U. S. Army, who spoke most entertainingly of, Mr. Swasey's accomplishments in designing and manufacturing instruments of precision, particularly for the use of artillery in range finding: Dr. William Wallace Campbell, Director of the Lick Observatory, and President of the University of California, described Mr. Swasey's, contribution to astronomical advancement by his notable development of the largest telescopes in this country.

Jan 1, 1924

By Robert L. Akre

When Marco Polo visited China in the 13th century, no one knew what black powder was except the Chinese; they knew enough to make dazzling fireworks with it. But the realization that black powder could also do useful work came much later and, like all important discoveries, it altered the course of history. It was in the 14th century that black powder was first used to break rock in a very crude way; there were no drills and the powder was simply poured into cracks and exploded by setting it afire. Because its energy value was pretty low, the need for something more powerful was felt when the industrial revolution began. In the 1850s, miners began experimenting with liquid nitroglycerine on a limited scale. This was a very sensitive and dangerous explosive. Fortunately in the 1860s, Alfred Nobel succeeded in stabilizing nitroglycerine by absorbing it in kieselguhr-and a new product, dynamite, was born. With it, miners were able to unleash the great energy of nitroglycerine for blasting purposes. But dynamite was still a very sensitive explosive. In subsequent years, other explosives of various strengths and characteristics were developed, such as blasting gelatin, gelatin dynamite, ammonia dynamites, (all containing some nitroglycerine or nitrostarch), and liquid oxygen explosives. These products and their variations supplied the blasting trade for many years. A grained ammonium nitrate product containing some carbonaceous material entered the market in the 1930s. This explosive had below-zero sensitivity-meaning: a No. 6 blasting cap imbedded in it would not detonate it. A more sensitive initiator, called a primer, was needed to detonate this mixture. From Rags to Primacord to Solid-State The first initiator for an explosive charge was probably a rag slowly burning its way to the charge; this method was quite unreliable. Then came the burning fuse, which was an improvement. Next was the nonelectric blasting cap initiated by a fuse. With these initiators, a miner needed quick reflexes and good legs; upon lighting the fuse, he had to run immediately for cover. Development of the electric blasting cap that allowed for accurate timing eliminated this hazard; the electric cap, however, introduced other safety problems because of its susceptibility to extraneous electricity, e.g., ground currents, lightning, and static electricity. These caps also became available in millisecond delays. Development in the mid-1930s of Primacord, a detonating fuse insensitive to electrical currents or impact, further reduced blasting hazards, and is generally acknowledged as the safest known means of initiation. Eventually, Primacord millisecond connectors also became available for delay patterns in blasting. In the mid-1960s, the Primadet delay was introduced; it is a practical nonelectric detonator system that offers the precise timing of electric blasting caps-and is immune to the hazards or effects of extraneous electricity. Recently, Research Energy of Ohio, Inc. introduced a new type of solid-state blasting machine that combines a sequential timer and delay caps. It enables the efficient breakage of rock with a minimum amount of shock, ground vibration, and noise. Improvements in Blast-Hole Drilling World War II created an enormous demand for coal and other minerals in the U.S. and elsewhere. Great efforts and large amounts of capital were spent to find new mineral deposits and develop better mining methods. But while mechanization in mining proceeded at a rapid pace particularly in open-cut work, there was a definite lag in developing new or improved machines for drilling blast holes. The industry continued to depend largely on horizontal, churn, and pneumatic drills. No better machine was available for large scale production. The need for improvement in this phase of mining became more acute in the post-war years. Despite efforts toward further mechanization, mining costs rose rapidly because of mounting inflation and increasingly high wages. In most operations, drilling and blasting the overburden became the principal item of cost. Therefore, whatever size holes were being drilled, the holes had to be spaced so that any foot of the bore hole could be loaded with the maximum load required for the number of cubic yards of material that each foot of the hole was carrying. With the smaller holes that were being drilled, the proportion of drilling cost to the total drilling and shooting cost was much higher than it would have been with larger holes (because of the closer spacing required by smal-

Jan 1, 1977

By David R. Mitchell, R. M. Fleming

MANY trends were evident in the coal industry during 1951. Some were favorable for the industry; others were not. Probably those having the most far-reaching consequences are those affecting coal's markets. The rapid dieselization of many railroads and the continued trend toward oil and natural gas for home heating has caused serious dislocations in various mining districts. Mines have been forced to close down or to work on a reduced time basis. Conversely the increased activity in the metallurgical industries has increased the demand for coking and special purpose coals, and the growing production of electric energy has increased the demand in certain areas for steam coals. The increased demand for metallurgical coal and for steam raising by the large utilities is more than equal tonnage-wise to the loss of coal to railroad dieselization and conversions to oil and gas in the domestic market. Since much of the expansion is at captive mines of large corporations, many commercial operators supplying railroad and domestic users have had their markets curtailed without any compensating demand from other sources. Feverish activity was in evidence in many areas by commercial operators attempting to find new markets. The Norfolk and Western Railway is the, only major American railroad committed to the burning of coal. It has an exceptionally good cost record. During 1951, fifteen additional modern coal-burning steam switching locomotives were authorized for construction in the company's Roanoke shops at a cost of about $1,450,000. When the new order is completed the road will own a total of sixty locomotives of the modern-switcher type, including thirty acquired by purchase last year. The Norfolk and Western today is the only American railroad building its own motive power. All of these locomotives burn coal. Production Coal production in the year 1951 will approximate 570 million tons of anthracite, bituminous coal, and lignite. Of this, approximately 7 pet is anthracite. Total production is approximately 30 million tons more than in 1950 and reflects the increase in general industrial activity. Exports are expected to be close to 50 million tons. The industrial stockpile is close to 75 million tons, the highest it has been since 1943. With the exception of the usual local stoppages the year 1951 was unmarked by labor disputes. It was a year of good labor-management relations with a negotiated wage increase unmarred by a work stoppage. This may be the beginning. of an era of sensible negotiations to find agreeable settlements of disputes without the usual protracted bickering and industry-wide strike. The United Mine Workers of America has condemned wildcat strikes, stating that in nearly every, instance proper grievance procedures have not been instituted. Government defense organizations, perhaps profiting by their experiences during World War II, are pursuing a more enlightened program with regard to the fuel requirements of the nation. Many prominent officials have stated that wherever possible coal should be considered the primary source of fuel in all defense expansion. With the increased consumption of steel by defense projects, approval of transportation facilities for liquid and gaseous fuels have been refused where these fuels would enter a coal producing area. Liquid and gaseous fuel producers also have failed to provide satisfactory evidence that they have sufficient reserves and are capable of supplying their product in adequate amounts for the periods of time required. Realization has at last become prevalent that the hydro-electric power installations in several areas are insufficient to handle increased demands.' Steam generating plants are being constructed in these areas and equipped to burn coal. Most notable of these, is the TWA area whose supplemental steam power plants are expected to consume 10 million tons of coal per year when completed. The Pacific Northwest is another area which is expected to follow the same pattern. Nearly all new steam-power generating plants are being equipped to burn coal either as a primary fuel or as an emergency measure. Metallurgical Coal The steel and other metallurgical industries are expanding rapidly to meet increased industrial demands and defense orders. Since these industries are dependent on coke, coke has had a year of high production and can be expected to break all existing records when steel-plant expansions are completed. Most notable of the expansion projects is that of the Delaware River area where the iron ore will be received by ship from Canada and South America. U. S. Steel is only one of several steel corporations that are planning on putting integrated steel producing units in this area. The Defense Solids Fuels Administration announced in December that through. November 30, 1951. 29 projects in eight states, with a total cost of

Jan 1, 1952

By John D. Roach

DURING an investigation of the yttrium-hydrogen system aimed at producing solid yttrium hydride specimens containing various amounts of hydrogen, it was observed that yttrium containing approximately 2 wt pct H exhibited a tendency to crack and crumble to a powder on standing in air at room temperature. It was also observed that longer hydriding times, at a given temperature, increased this susceptibility to powdering without an increase in hydrogen content, also that moisture in the air is necessary for the observed effects to occur. Even if cracking did not occur, there was a continual formation of a light gray powder on the as-treated surface of the hydrided yttrium and this reaction continues until the entire hydrided piece has been reduced to a powder. Storing the hydrided specimens in the absence of air or removing the surface either by machining or grinding were effective means of preventing this disintegration of hydrided yttrium. In an attempt to determine the reason for this powdering phenomenon, the surfaces of a number of as-hydrided yttrium specimens were examined by X-ray techniques. In all cases the X-ray pattern obtained showed the major phase to be yttrium hydride (YH2) as would be expected since the specimens contained 2 to 2.2 wt pct H. In some cases a trace of yttrium oxide was observed. There was also a third phase present on the surface of these hydrided specimens which could not immediately be identified. This unknown phase was a face-centered cubic material, NaC1-type structure, with a lattice parameter of 4.855 and a calculated density of 5.914 g per cc. Very slight hand polishing of the surface of the hydrided yttrium specimens completely removed both the unknown phase and the traces of oxide so that only the yttrium hydride pattern remained. Based on the X-ray patterns the quantity of the unknown phase on the surface of the hydrided yttrium appeared to be directly related to the susceptibility of the material to powdering. Work at the Denver Research Institute on the yttrium-nitrogen binary system showed that yttrium nitride (YN) is a face-centered cubic material with a lattice parameter of 4.878A and a density of 5.890 g per cc. They also noted that this compound rapidly disintegrated to a powder on standing in air. The unknown pattern observed in the above specimens corresponds very closely to that of the nitride—fcc structure, 4.885 parameter, and density of 5.914 g per cc. The presence of this thin film of nitride on the surface of the hydrided specimens probably accounts for the observed powder formation and crumbling. The nitride reacts with the water vapor in the air (verified by private communication from Dr. C. Huffine, General Electric Co.) to yield yttrium oxide and ammonia. Ammonia is readily detected when hydrided yttrium specimens were allowed to stand in bottled moist air. The powder formed on the surface of the hydrided specimens was shown by X-ray analysis to be yttrium oxide. This reaction appears to occur primarily at the grain boundaries since discrete particles of yttrium hydride separate from the specimens during this powdering process. The reaction of yttrium nitride with water vapor is believed to be as follows: 2YN + 3H2O - Y203 + 2NH3. Despite the fact that this nitride is present only as an extremely thin surface film, if the above reaction is not prevented by removing this film from the surface either by machining or grinding, the reaction continues until the entire hydrided piece has been reduced to a powder. To account for this continuation of the reaction, it is believed that the following reactionalsooccurs: 2YH2 + 2NH3 -2YN + 5H2. The nitride produced by the latter reaction reacts in turn with water vapor. The reaction therefore becomes autocatalytic and continues until the hydride has been consumed and the entire piece reduced to oxide powder. The amount of nitride required to initiate this reaction is quite small and this nitrogen contamination can occur from a number of sources—hydrogen gas employed, minute leak in the hydriding apparatus or even from degassing of the reaction vessel itself. Longer hydriding times increase the possibility of nitrogen contamination and this is especially true when a dynamic gas system is employed in the hydriding process. The production of stable, solid hydrided yttrium is dependent on the complete absence of nitrogen contamination during processing. If such contamination does occur, powdering of the hydrided product can be prevented by removing the nitride from the surface e.g. grinding or by preventing access of air to the pieces e.g. sealing in wax or plastic. The author wishes to express his appreciation to General Electric Co. for sponsoring this research and for permission to publish the results of work under Subcontract AT-93.

Jan 1, 1962