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By C. H. North, L. E. Lynd, W. W. Anderson, H. Sicurdson

Since the composition and structure of the beach sand concentrates correspond so closely to what would be expected of ilmenites that have been altered by oxidation and leaching, there is no reason to postulate the existence of the hypothetical compound, arizonite, to account for the composition of titaniferous beach sand concentrates. The four concentrates studied are examples of the different products that can result from various degrees of alteration of primary ilmenite. CONSIDERABLE uncertainty is revealed in the literature regarding the nature of the titanium minerals which make up the bulk of the heavy, opaque fractions of numerous beach sand deposits of the world. An investigation was made, therefore, of beach sand concentrates of North Carolina, Florida, Brazil, and India. Magnetic concentration, X-ray, and microscope data were obtained which show that these concentrates consist essentially of ilmenite and its alteration products. The alteration, brought about by oxidation and leaching of iron values, has resulted in upgrading the ores to a range of 56 to 64 pct TiO², as compared with 52.7 pct in ilmenite of theoretical composition. Conclusions drawn regarding the nature of the dominant titanium-bearing mineral in beach sand deposits have been based mainly on chemical composition, specific gravity, and petrography. This material has usually been referred to as ilmenite or weathered ilrnenite.: It has also been referred to as arizonite because in chemical composition it resembles an Occurrence in in which was described by Palmer' in 1909. The chemical composition of Palmer's arizonite corresponded closely to the formula Fe²O³ . 3TiOs. From approximate measurements of crystal angles on a large imperfect crystal with rounded faces, the

Jan 1, 1955

By Joseph P. Hodgson

Since about 70 per cent. of the total cost of mining is due to underground work which is out of sight, it is essential that expenditures should be made here to the best advantage. A great many mistakes have been made which were expensive, but perhaps these have not even been detected by mine owners. In the future these may be minimized to some extent, especially if there is cooperative effort on the part of each employee. I have been interested in this subject for some years and have tried to deduce principles and methods. These have proved highly advantageous and may also be of help to others. Some corporations, like the United States Steel, and the Cleveland-Cliffs Iron Co., have done a great deal in this field by having stated meetings of their organizations, with the view to interchanging ideas among their men and educating them along the lines of concerted effort. Since no man knows all about the various branches of mining, it is advisable that frequent meetings of the operating department be held for the interchange of ideas and that all members of the organization have an opportunity to express themselves on the various subjects. It has often been found that in discussions between heads of departments, foremen and bosses, many valuable suggestions may be obtained which promote the best interests of the company. The method regarded as the most conducive to cooperative effort, and pursued by the organization, is to analyze and develop the different phases of various mining subjects at regular meetings. Nine Foremen's Dinners In the latter half of 1912, the Copper Queen Consolidated Mining Go. gave monthly dinners to the men in the operating departments. Those who attended were superintendents, foremen, shift bosses, engineers, geologists, and heads of all departments, making a total of about 75 men. After the dinner, lectures were given on subjects which pre-

Jan 1, 1917

By W. P. Dyrenforth, W. E. Horst

Although, separating or concentrating minerals, based on differences in. their magnetic properties has been practiced for years1 the early industrial applications of magnetic separators were involved with the most highly magnetic materials. These early separators were used to concentrate magnetite, separate metallic iron from furnace products, and separate iron and brass turnings. Next, the addition of a pretreatment operation, such as roasting or calcining, to transform certain iron-bearing minerals into a highly magnetic compound that could readily be separated from the altered mineral mixture using existing magnetic separation machines was added to the flowscheme. As the number of magnetic-separator installations grew, steady development of better equipment evolved including the design and implementation of induced magnets having high-intensity fields, These developments of course greatly expanded the field of magnetic separation and made it possible to commercially separate or concentrate very weakly magnetic minerals which previously had been considered as nonmagnetic minerals. A number of different designs of magnetic separators were well developed and the unit operation of magnetic separation was gaining wide acceptance in mineral processing operations when two events occurred that dampened these developments. First, the Mesabi iron range with its direct-shipping iron ore was discovered and placed into operation. This of course significantly reduced the need for magnetic separation to meet the raw material requirements of the iron and steel industry. Second, the advent of selective froth flotation, was so successful in solving many mineral process problems that electrical concentration techniques being developed at that time, including magnetic-separation methods, were either terminated or received low priority ratings. During the past two decades interest has been renewed in the use of electrical concentration methods to solve mineral separation problems. As the direct-shipping iron ore reserves are depleted more emphasis has been placed on magnetic upgrading of lower value iron ore available throughout the world. In addition, magnetic separation techniques have found numerous applications in the non-metallic and industrial minerals industry to supplement froth flotation and thus add to the variety of beneficiation methods available.

Jan 1, 1971

By P. Gianella Vincent

Barite deposits are of widespread occurrence in Nevada but there are few pro-ducing properties; most of the latter are in northern Nevada. The production of the state is small at present-in the neighborhood of 15,000 tons annually-but is steadily increasing. The barite occurs in veins and also as replacement deposits in lime-stone. The bulk of the production has come from the replacement deposits. It is thought that the barite was deposited from rising hot waters similar to-and probably contemporaneous with-those responsible for some of the metallic ores of the state. This paper discusses only the deposits in northern Nevada. THE commercial mining of barite did not begin in Nevada until 1916 but although the production has been small there has been a rapid increase in tonnage during the past several years. Barite is widely distributed in the state and production comes from at least nine of the seventeen counties. Apparently this is not generally known, as only two counties are mentioned in a recent publications dealing with barite. The increase in output is due largely to recently discovered barite deposits in northern Nevada. The principal production has come from the northern portions of Lander and Eureka counties; smaller amounts from Elko County. The discussion in this paper is confined largely to the deposits in these counties. Most of the producing area is tributary to the Western Pacific and Southern Pacific Railroads, whose tracks lie along the Humboldt River. Barite is known from other northern counties but so far the production has been small. The output has come entirely from veins and replacement deposits, the latter largely in sedimentary rocks. In general, the barite from veins is white; that from the replacement deposits usually is dark gray to black, although some is light gray or white. Most of the veins contain sulphides and many barite-bearing veins have been worked for their content of base or precious metals.

Jan 1, 1940

By J. M. Lovejoy

Tests are described that show that back pressure on flowing wells is a waste rather than a conservation of natural forces. Stop-cocking, however, gives encouraging results. VARIOUS estimates have been made as to the percentage of oil left in a field after the wells have become so small that it is no longer practical to produce them. Engineers have given the matter much study and can substantiate their figures by data taken from fields from the Appalachians to California. The average oil sand has a porosity of about 20 per cent., which gives a capacity per acre-foot of approximately 1500 bbl. The sand thickness in Oklahoma pools averages 20 ft. With 20 per cent. porosity and a 20-ft. sand thickness, the capacity per acre is 30,000 bbl., yet these pools will seldom yield more than 5000 bbl. to the acre. These figures support the theory that at least 50 per cent. of the oil remains in a sand after all known methods to recover it have been used. Certainly we can never recover all the oil, unless in years to come oil becomes so rare and yet so necessary that the price will justify sinking shafts into the abandoned fields and regular mining methods of drifting and stoping. However, with improved methods of production and conservation of the natural agencies of expulsion, we should be able to increase recovery. It is with this in mind that this paper, relating to the effect of back pressure on wells, is presented. Except in the fields where production is caused by hydrostatic pressure, the chief agency for getting, oil out of the sand into the hole is the gas that occurs with the oil. After the pressure has declined, probably gravity also is a factor, but not an important one. With a given amount of oil in a sand and a given amount of gas occurring with the oil, the ratio of gas volume per barrel of oil is the key to the ultimate recovery from that sand. Our efforts should be along lines that will, lower this ratio and make the gas, the agency given us by nature, do its work better and yield more of the oil, of which it is a part.

Jan 1, 1924

By E. C. Houston, R. A. Laurence, F. A. W. Davis, L. L. McMurray, H. S. Rankin

This paper is coodensed from several reports by members of the staff of the Minerals Testing Laboratory of the Tennessee Valley Authority, on a series of experimental tests in the beneficiation of barite of the Valley area. These experiments were conducted upon a large number of samples taken from several mines in three different districts. The area contains numerous producing deposits, nearly all of which are hampered by the high iron and silica content of the ores. Because of the small difference in specific gravity between the iron oxide and the barite, a gravity separation is generally poor. The removal of the iron thus offers a special problem. Some of the operators have turned to magnetic separation to meet the shipping requirements for less than one per cent iron. The present experiments were conducted to determine the application of decrepitation or flotation in simplifying the concentration of the barite by removing the iron oxide and silica in one operation. Practically all the barite marketed in the area has been as "off-color" crude. The bleaching studies were made to determine the bleach-ability of the ores to alleviate this inferior grading, placing them on the market as bleached barite. Geology Barite has been produced at many places in the Tennessee Valley area, and prospects and minor deposits are known at many other places, but practically all the production of barite in the Valley has been from the Sweetwater district of East Tennessee. Other leading areas of former production are the Tazewell-Russell counties areas of southwest Virginia, the Del Rio-Stackhouse district of East Tennessee and western North Carolina, and the Fall Branch district of upper East Tennessee. The areas described in this paper are those from which samples used in the concentration tests were obtained.

Jan 1, 1942

By H. S. Rankin, F. A. W. Davis, R. A. Laurence, L. L. McMurray, E. C. Houston

This paper is coodensed from several reports by members of the staff of the Minerals Testing Laboratory of the Tennessee Valley Authority, on a series of experimental tests in the beneficiation of barite of the Valley area. These experiments were conducted upon a large number of samples taken from several mines in three different districts. The area contains numerous producing deposits, nearly all of which are hampered by the high iron and silica content of the ores. Because of the small difference in specific gravity between the iron oxide and the barite, a gravity separation is generally poor. The removal of the iron thus offers a special problem. Some of the operators have turned to magnetic separation to meet the shipping requirements for less than one per cent iron. The present experiments were conducted to determine the application of decrepitation or flotation in simplifying the concentration of the barite by removing the iron oxide and silica in one operation. Practically all the barite marketed in the area has been as "off-color" crude. The bleaching studies were made to determine the bleach-ability of the ores to alleviate this inferior grading, placing them on the market as bleached barite. Geology Barite has been produced at many places in the Tennessee Valley area, and prospects and minor deposits are known at many other places, but practically all the production of barite in the Valley has been from the Sweetwater district of East Tennessee. Other leading areas of former production are the Tazewell-Russell counties areas of southwest Virginia, the Del Rio-Stackhouse district of East Tennessee and western North Carolina, and the Fall Branch district of upper East Tennessee. The areas described in this paper are those from which samples used in the concentration tests were obtained.

Jan 1, 1942

By P. P. Reichert, L. S. Gournay, N. T. Burdine

An investigation of equivalent pore entry radii in typical samples of petroleum reservoir rock and the pore volume associated with each value of pore entry radius has been made. Theoretical discussions together with experimental procedures for obtaining pore entry radii and the distribution of pore volume with pore entry radii are presented. Experimental results on a number of core samples, along with typical distribution curves, are shown. Data on the per cent of the pore volume filled by mercury at a pressure of 1500 psi are included. The results of re-runs of samples, made possible by regenerative apparatus, show the repeatability of the data and indicate the amount of physical change in the samples by mercury penetration. Theoretical equations for calculating permeability from pore size distribution data were derived and the results of such calculations are compared with measured gas permeability data. The effect of the shape, surface area, and weight of the sample on the pore size distribution of reservoir rocks was investigated experimentally. Mercury capillary pressure curves are compared with those obtained by the porous diaphragm method using pas to displace water. Standard core analysis techniques, in general, lead to quantities which are statistical averages of the varying properties of the samples under examination. Although such statistical information has real value in predicting the gross performance of porous bodies. it fails to provide fundamental information concerning the properties of the porous medium itself or any processes which may be occurring in it. For example, a gas permeability measurement on a core sample is an indirect way of determining an average pore radius for that particular sample. Since there are many combinations of pore radii that will give the same radius. and, hence, the same permeability, no information is obtained on the pore size distribution. Furthermore, similar values in permeability do not imply similarity in other properties of a porous medium. For instance, it is possible to have two core samples with identical permeability which would have different residual oil contents at the end of an air-oil drive, or even different amounts of interstitial water. It has been recognized for some time by the petroleum industry that a determination of pore size distribution for porous reservoir rocks offered promise of increased understanding of fundamental flow processes in the porous matrix. and therefore of petroleum res- ervoir performance in general. There have recently been published several methods for determination of pore size distribution in porous materials. A report is given here of the modifications in equipment and technique required to adapt one of these methods to measurements on petroleum reservoir core samples. Although only a few correlations or applications of the method are available for presentation at this time, the technique is brought to the attention of the industry so that the opinions and experience of others with this or similar techniques may be exchanged. It seems possible that the method will have wide application in the future. METHOD There are three general methods which may be employed to measure the pore size distribution in naturally occurring rock formations. One method1 is based on experimentally determined adsorption isotherms for calculating the surface area of the porous medium. Knowing the surface area and the pore volume, a rough estimate of the pore radius can be made. Since this method depends on the thickness and uniformity of the adsorbed layer, the validity of the results would be highly questionable. A second method utilizes capillary pressure data obtained by static dis-

Jan 1, 1950

By B. B. Zavoico, J. G. H. Crump, P. P. Gregory

West Texas was the scene of greatly increased oil activity during 1937, producing 75,743,000 bb1.l in that year as compared with 61,901,-000 bb1.2 in 1936, an increase of 22.36 per cent. The annual total of wells completed increased from 15863 in 1936 to 28062 in 1937, an increase of 76.92 per cent. Of the total completions in 1937, 2464 were oil wells,2 11 gas wells2 and 331 dry holes.2 The marked increase in the number of oil wells completed in West Texas during 1937 had a substantial effect upon the daily average production per well, which decreased 20.84 per cent from December 1936, when a total of 5310 wells3 produced 5,236,467 bbl.3 for an average of 31.81 bbl. per well per day to December 1937, when 7571 wells2 with a total production of 5,910,257 bb1.2 averaged 25.18 bbl. per well per day. Drilling blocks and checkerboard acreage were being acquired following geophysical work in the northern end of the Permian Basin area, composed of Bailey, Cochran, Hockley, Yoakum and Terry Counties, presaging extension of active development northward. During 1937, at one time 30 geophysical crews were working in West Texas, and an average of 15 to 20 crews was active in this area throughout the year. Discoveries Wasson-Denver Field.—Wasson-Denver field in Gaines and Yoakum Counties was the outstanding field discovery of the year. Production is from porous limestone found at about 5000 ft., and an average well is good for from 300 to 500 bbl. of crude oil per day through 3/4-in. choke. The discovery well was drilled by A. G. Carter and others on the Wasson Ranch, Gaines County, and the field has since been extended into Yoakum County. At the year's end 21 wells had been completed, producing

Jan 1, 1938

By James W. Burns

Thin, heavily doped n-type layers of GaSb have been grown on p-type GaSb substrates. Techniques have been developed for the growth of the n-type layers from a tellurium-doped gallium-rich solution. The solution used consists of 95 at. pct Ga and 5 at. pct Sb. The process consists of immersing the p-type wafer in the solution at a temperature slightly above the liquidus temperature, holding briefly to permit dissolution of the substrate surface, then decreasing the temperature to a value slightly below the liquidus to obtain 1 HE resistivity of n-type GaSb varies linearly with applied hydrostatic pressure, while the resistivity of p-type GaSb is insensitive to such pressure.1,2 The growth. Growth from a solution of GaSb in tin will also be described. In either case the substrate is clamped to a shelf at one end of a graphite boat, and immersion of the wafer and subsequent decanting of the solution is accomplished simply by tilting the furnace. The process is useful for the formation of p-n junctions in III-V compounds and has the advantage that the problems normally associated with diffusion of Group VI elements are not present. Layers up to 4.0 mils in thickness have been grown by the process. material therefore should be useful in a hydrostatic pressure-sensing device. A practical hydrostatic pressure sensor, however, requires the fabrication of GaSb sensing elements of several hundred ohms resistance. Attempts were made to prepare such elements by diffusion, taking advantage of the high sheet resistance of the thin diffused layers and depending upon the p-n junction to provide isolation from the base layer. Additionally, thin layers of conductivity type opposite from that of the base layer were pre-

Jan 1, 1969

By Lynn G. Howell, Alex Frosch

In a previous article1 we have described a technique for measuring the relative intensities of gamma rays from the radioactive elements occurring naturally in geological formations along the walls of a borehole. The apparatus consisted of two Geiger-Müller tubes mounted inside a pressure-tight chamber. Each counter tube was coupled separately to an amplifier and a frequency meter at the surface by means of a multiconductor cable upon which the chamber was suspended. The output currents of the two frequency meters were recorded on a photographic paper as the chamber was moved in the hole. These traces showed remarkable correlation with the geologic formations, as evidenced by comparison with commercial electrical logs.2 Owing to the penetrating power of the gamma rays, logs may be taken in both open and cased boreholes. The apparatus has recently been changed somewhat. One of the counter tubes has been removed and a stage of amplification has been added inside the chamber. This arrangement seems to give a more favorable signal-to-noise ratio and satisfactory logs can be now made in cased holes and also in open holes as previously. Briefly described, the chamber moving in the hole is made of 3½-in. drill pipe and is about 10 ft. long. There is an additional extension about 2 ft. long at the top, inside which cable connections are made. The Geiger-Müller tube is mounted inside the bottom end of the chamber. Above this is the vacuum-tube amplifier with its batteries and transformer. In the top part of the chamber, small 45-volt batteries are mounted, which in part supply the high voltage for the counter tube. Additional voltage is supplied from the surface through the multiconductor cable upon which the chamber is suspended. Also, the output of the transformer in the single-stage amplifier is coupled to another single-stage amplifier at the surface through this cable. The surface amplifier is coupled to the Thyratron-controlled frequency meter, the tank circuit of which consists of a one megohm resistor across which is a bank of condensers varying in

Jan 1, 1940

By J. W. Harden

AT our meeting in October last we saw in operation at Pittsburgh, the comparatively modern process of the utilization of small coal by washing, by an arrangement similar to that of Bérard or Morrison. The small coal washed was that of an old pile, the refuse of the mining of the Pittsburgh bed, and which had long lain uncared for. Value was thereby restored to it when it was converted into a very good coke. This circumstance led to comments on the mountains of broken coal lying wasted, and in its present condition worse than useless, in the neighborhood of the mines of the Wyoming Valley, though they are not confined to that district. Some things were said condemning the course which produced it, some were left unsaid. Of a system that destroys one-half the coal-bed in producing the other half there can, however, be but one opinion. Schemes have been suggested for the utilization of present accumulations which, if successfully applied, would in so far be beneficial. More than ordinary attention is now being given to the same subject in England; a Mr. Barker has invented a means by which he amalgamates the "dust," too fine to burn in ordinary grates, with a composition he calls "diamond cement," producing blocks of coal said to resist water, both hot and cold, and which a smart blow will only break to pieces, not cause to crumble. But any scheme less than the one which will prevent the wasting of coal, which still goes on, though that involves the abandonment donment of the breaker, will only be one of expediency; and the latter can only be done by the aid of the consumer. But the wasting of coal is not alone with the breaker ; much is made in the mine. The cause is not far to seek ; the remedy is with capitalist and owner. Owners and consumers then are alike interested, and they have it in their power, in the one case, to mitigate, in the other, almost entirely to remove the cause of the evil. Of consumers there is one in every

Jan 1, 1873

By Alex Frosch, Lynn G. Howell

In a previous article1 we have described a technique for measuring the relative intensities of gamma rays from the radioactive elements occurring naturally in geological formations along the walls of a borehole. The apparatus consisted of two Geiger-Müller tubes mounted inside a pressure-tight chamber. Each counter tube was coupled separately to an amplifier and a frequency meter at the surface by means of a multiconductor cable upon which the chamber was suspended. The output currents of the two frequency meters were recorded on a photographic paper as the chamber was moved in the hole. These traces showed remarkable correlation with the geologic formations, as evidenced by comparison with commercial electrical logs.2 Owing to the penetrating power of the gamma rays, logs may be taken in both open and cased boreholes. The apparatus has recently been changed somewhat. One of the counter tubes has been removed and a stage of amplification has been added inside the chamber. This arrangement seems to give a more favorable signal-to-noise ratio and satisfactory logs can be now made in cased holes and also in open holes as previously. Briefly described, the chamber moving in the hole is made of 3½-in. drill pipe and is about 10 ft. long. There is an additional extension about 2 ft. long at the top, inside which cable connections are made. The Geiger-Müller tube is mounted inside the bottom end of the chamber. Above this is the vacuum-tube amplifier with its batteries and transformer. In the top part of the chamber, small 45-volt batteries are mounted, which in part supply the high voltage for the counter tube. Additional voltage is supplied from the surface through the multiconductor cable upon which the chamber is suspended. Also, the output of the transformer in the single-stage amplifier is coupled to another single-stage amplifier at the surface through this cable. The surface amplifier is coupled to the Thyratron-controlled frequency meter, the tank circuit of which consists of a one megohm resistor across which is a bank of condensers varying in

Jan 1, 1940

By F. L. Wolf

THE tests here described were made to obtain information regarding costs, efficiency, etc. of baking cores in an oil-fired oven, and two electric ovens, which were installed, early in 1920, in the core room of The Ohio Brass Co. and were used almost continuously during the rest of that year. Operating costs were rather high so a complete test was undertaken early in 1921. The ovens will be referred to as Nos. 1, 2, and 3. Nos. 1 and 2 are electric ovens of different makes while No. 3 is an oil-fired oven made by the firm that made No. 2. The three are equipped with similar ventilating devices. They have full-height doors at front and rear. The cores are placed on iron racks, which are lifted by Cowan trucks and rolled into the ovens through the front doors. When baked, they are removed through the rear doors. Fig. 1 shows the general plan of the electric ovens while Fig. 2 shows the plan of the oil-fired oven. Oven No. 1 is 91 in. (231 cm.) wide, 83 in. (210 cm.) high, and 79 in. (200 cm.) deep, inside measurements. The walls are constructed in, panels about 18 in. (46 cm.) wide and 4 3/16 in. (10.6 cm.) thick, packed with blocks of insulating material and covered with sheet iron. The concrete floor on which the ovens set is 13 in. (33 cm:) thick. A recess about 5 in. (13 cm.) deep was cut in the floor to provide room for the heating units. Channels and plates supported. on I beams serve as' supports for the trucks and racks. The ventilating system consists of a Sirroco No. 1 ½ fan, connected so as to draw air from the top of the-oven or from the room, through damper C, and to deliver it either to the bottom of the oven or to the floor; the delivery is controlled by the vane A. The fan and pipes are covered with ¼ n. (6.3 mm.) asbestos cement lagging.

Jan 4, 1922

By S. A. Falconer

This paper deals with the practical application of the Dutch State Mines cyclone separator for fine-coal cleaning. The more important operating variables are discussed, and results of a number of continuous- scale tests on various fine coals with a 6-in. cyclone separator are given. Descriptions of the Cyanamid Pilot Plant and the 50 tph Cyclone Separator Plant at the Emma Washery in Holland are included.

Jan 7, 1950

By Wilbur Nelson

ALL of our accounts of the discovery of copper ore at Ducktown, Tenn., state that the discovery was made in August, 1843, yet it would appear that samples of copper from this district were found by the Spanish explorer, DeSoto, when he wandered into Southern Tennessee, in 1539, in his four years of exploration through the Southern States. The following quotation is taken from his diary: "Towards the north there was a province named Chisca; and that there was a melting of copper, and of another metall of the same colour, save that it was finer, and of a farre more perfect colour, and farre better to the sight, and that they used it not so much, because it was softer. And the selfe same thing was told the governor in Cutifa-Chiqui, where we saw some little hatchets of copper, which were said to have a mixture of gold. But in that part of the country it was not well peopled; and they said there were mountains, which the horses could not passe; and for that cause, the governor would not goe from Cutifa-Chiqui directly quicker." DeSoto sent two of his company to try to find these mines, but after five days' wandering through the mountains they returned, stating that their guides had become lost. Although the Ducktown area may have been known to the ancient Indians, it was not until August, 1843, when a Mr. Lemmons, who was panning for gold on Potato Creek, in the Ducktown basin, found some reddish-brown decomposed rock, which he supposed to be gold, that the copper deposits were actually discovered. His disgust on finding that this yellow metal. was not gold was so great that he did not. try to develop his find. In March, 1847, B. C. Dugger erected an iron forge at this same place, but was unable to work the iron as it contained so much copper that on cooling it would break to pieces. The finding of copper in the iron ore by Mr. Dugger led to further explorations; and in April, of the same year, A. J. Weaver, who was passing through that country, told the people that the black rocks they had dug out were rich copper ore. Mr. Weaver began the first mining in this district.

Jan 10, 1924

By John K. Hammes, Stanley D. Michaelson

The material presented in this chapter is supplemental information on those significant aspects of open-pit copper mining that are to an extent unique and therefore not detailed in previous sections covering the fundamentals of open-pit mine planning, operations and maintenance. In addition, tabulated cost and operating data are presented for a variety of open-pit copper mines. 13.3-1 History. The history of the civilized use of copper began at the end of the Stone Age when man discovered that the red metal, in the form of native copper, could be readily worked into a variety of weapons and tools which simplified the primitive requirements for survival. Almost concurrently, the high value of these early copper products became so widely known that they soon assumed major importance as trading commodities. Copper and copper-alloyed artifacts, even though produced in very limited quantities by ancient miners and metalworkers in a few parts of the Near East and the Western Hemisphere, were so valuable that early warriors and traders carried them into nearly all the world's known areas of importance. As far as copper is concerned, the Bronze Age, at sometime around 8000 BC to 6000 BC, marked the vague, little-known beginning of metallurgy. Man learned to alloy the valuable red metal to make it harder and tougher; its use multiplied as did the variety of weapons and tools made with the gradually increasing metallurgical and fabricating skills. By 3000 BC bronze alloy products became relatively widespread ; copper mining activities assumed tremendous importance and the mines on the Isle of Cyprus developed into prized possessions of each Mediterranean empire from the times of Egyptian supremacy to well beyond the decline of the Roman Empire.

Jan 1, 1968

By V. Damiano, M. Herman

CELLULAR substructure observed in metal crystals grown from the melt. has been studied extensively'-' and is attributed to the existence of a constitutionally supercooled zone in the liquid ahead of the solidifying interface. The mathematical description of this process has been given in terms of the concentration of solute in the liquid phase, the rate of solidification, and the temperature gradien.t in the liquid as the only variables.5 This technical note presents some evidence of 1) the effect of crystal orientation on some aspects of cellular growth, and 2:) the degeneracy of these cells into dislocation arrays. The zinc single crystals used in these studies were alloyed with cadmium sufficient to produce the constitutional supercooled cellular substructure. Crystals containing 0.05 pct Cd exhibited substructure formation for a growth rate of 10 cm per hr and a temperature gradient of 15°C per cm in accord with the theory. The growing liquid-solid interface was examined after we liquid had been decanted away in a fashion similar to that described by Rutter and Chamers.' The cellular substructure was also observed after polishing and etching the surface directly behind the decanted interface with a solution of HNO, and water. Fig. 1 is a photomicrograph of a typical polished and etched surface revealing substructure, the cleavage plane, and twins. The crystal has been grown with its basal plane parallel to the direction of growth and the plane of the micrograph is per-

Jan 1, 1960

By Eugene A. Stephenson

In most instances the fluids produced from underground reservoirs have been described as they appear at the surface, and usually it has not been necessary to distinguish between surface and reservoir phases. More recently it has become imperative to recognize the fact that changes in phase may occur between the reservoir and the receiving unit. The simple terminology of "wet" and "dry" gases and "crude petroleum oil" served our needs fairly well in the shallow, low-temperature and low-pressure fields. It has been left to the legislatures, regulatory commissions, and courts to decide whether a field is or was a gas field, an oil field, or both. This they have done by direct definition and also by implication. For example, in Texas:' (d) The term "gas well" is any well (a) which produces natural gas not associated or blended with crude petroleum oil at the time of production, or (b) which produces more than one hundred thousand (100,000) cubic feet of natural gas to each barrel of crude petroleum oil from the same producing horizon, or (c) which produces natural gas from a formation or producing horizon productive of gas only encountered in a well bore through which crude petroleum oil is also produced through the inside of another string of casing. (e) The term "oil well" is any well which produces one (1) barrel or more of crude petroleum oil to each one hundred thousand (100,000) cubic feet of natural gas. In the state of Louisiana, the same general result is achieved largely by the following paragraph :* Wells producing both oil and gas shall not waste or blow into the air an amount of gas of more value at three cents per thousand cubic feet, than the market value of the oil recovered. The Commissioner of Conservation shall allow a reasonable time to determine the status of any well. This means that for wells making both oil and gas, if n represents the price of oil in dollars, and x the allowable gas waste expressed in M cu. ft. Per day,

Jan 1, 1938

By Alfred Heggem

IT is the purpose of this article to describe methods recently introduced into the oil and natural gas industry to safeguard the lives of the workmen and to protect property from destruction. Only such drilling methods are described as pertain directly to the operations necessary to maintain the well under complete control at all times. Wells Formerly Drilled Without Controlling Equipment It may seem incredible that practically all wells, until recently, were drilled without the provision of any means for control. To drill a hole into a boiler carrying high-pressure steam without first providing means to control the escape of steam would be unthinkable, yet in oil fields wells are drilled into a gas or oil formation with a possible pressure of 300 to 1,800 lb. per square inch and a daily flow of 20,000,000 to 80,000,000 cu. ft. of gas or 1,000 to 15,000 bbl. of oil per day. Some wells have produced in excess of 100,000 bbl. of oil per day, but these are exceptional cases. In addition to the loss of product, one must consider the great danger attendant upon the promiscuous liberation of such an amount of explosive and inflammable substance.

Jan 1, 1916