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By M. E. Lombardi

The cost of maintaining the production of an operating oil company is one of the most important, as well as one of the most difficult to estimate, of the various items which go to make up the total cost of producing oil. In the opinion of many operators the cost of drilling and developing new wells, whose, production takes the place of the loss in production through decreased yield of the old wells, is considered an operating expense, for the reason that the total income-producing power of the property is not increased. The cost of these new wells may be added directly to production expense, or it may be charged to capital account, and this account depreciated to the same extent. In either case, after an oil company is on a satisfactory income-producing basis, the money for drilling new wells to maintain production must be taken from the income of the company. Three factors determine the cost of maintaining production: First, the rate of decline in yield of the wells; second, the cost of drilling and equipping new wells in terms of their production; third, the decrease in initial production of new wells as the property is drilled and gas pressure taken off the sands, etc. In order to check theoretical figures for the cost of maintaining production the writer, with the assistance of Reed Bush and Fred Tough, has compiled the following figures. It is necessary first of all to choose a' period of time during which production for the field or territory studied remains fairly constant. The longer the period of time over which this condition prevails, the better. It is also necessary to eliminate or allow for any extraneous condition which may have affected the production returns, such as the shutting down of a large number of wells, the bringing in of a well of exceptionally large yield, the opening up of virgin territory where the flush yield is greater than will be had from new wells in after years, etc. All these conditions are exemplified most simply in the case of the Coalinga field, and perhaps these figures are more truly prophetic than the two other cases given. In applying these figures to the future it is well to assume that the average yield of new wells will constantly de-

Jan 1, 1916

The ventilation of metal mines is becoming more of a fundamental requirement than it was 10 or even 5 years ago. There are many reasons for this, and in general they are based on economy or efficiency rather than health or safety, yet the latter enters into the picture in at least some instances. One Montana metal mine which had installed mine fans and a general ventilating system shut down the fan when there was a period of cessation of work; within a few weeks it was found that the underground timbers were becoming so covered with fungus that the fans were put into operation and thereafter continued in operation whether the mine was worked or not. The fungus soon disappeared and the cost of operating the fans was held to be far less than would be the numerous losses from timber decay which quickly started when cessation of air flow was encountered. A large iron ore mine in Michigan had much difficulty in holding men in a slicing region due to foul air under certain surface conditions as to direction of wind. Upon the placing of a moderate sized fan on the surface with some doors, stoppings and regulators underground, not only was the bad air condition removed but there was found to be a decided increase of tonnage per man per shift and timber decay was retarded to a very considerable extent. This particular mining company was rather inclined to be angry when I called attention to some of the what I considered very bad working conditions underground, and the mine superintendent for about a year and a half was on anything but friendly terms with me. Later on when the effect of the placing of the fan was found (the fan had been placed over his protest), that, man came through very nicely with a letter and congratulated me on the recommendation made and congratulated himself and the company on the conditions obtained after the installation of the fan. Poisonous Fumes after Blasting A copper mine in the Southwest with an ore of a high sulfide content has much difficulty due to poisonous fumes after blasting, and the, fan installation is as elaborate as those of many of the most nearly up-to-date coal mines, and coal mine splitting and regulating practices are being

Jan 1, 1927

By John M. Hartman

TWO systems are used for heating air in blast-furnace operations: I. The double surface system, in which a cast-iron pipe is heated on the outer surface, and, at the same time, heats the blast from its inner surface. This is simple in operation and gives a continuous effect, but is limited by 1100" F. as a maximum temperature of the blast. 11. The single surface system, by which large surfaces of fire-brick are heated, and air passed over the heated surface, absorbing the heat and carrying it on to the furnace. This system is more comylex than the double surface, as it invoives the reversing of the air and gas every hour and a half. The single surface system has two advantages: 1. The blast can be heated to a temperature of 1800° F. 2. The stoves are indestructible. From recent experience it has been found that 1300" F. to 1400' F. is the best average temperature for economy of coal for safe working. This is equivalent to a saving of 11/2 to 2 cwt. of coal per ton of iron over the extreme limit of cast-iron stoves. Independently of this, it is a strong point in favor of this system that the blast can be raised to a temperature of 1800° F. within an hour when the hearth is getting cold. All furnacemen know the ralue of a hot hearth for quality and quantity of iron. Cooling of a hearth occurs from leaky tuyeres, scaffolds, or heavy burden. When there is not sufficient coal at the tuyeres to seize on the oxygen of the entering air and convert it at once to carbonic oxide, there will not be enough heat to liquefy the cinder. Black cinder and poor iron are the results. The remedy is additional heat from the blast. If the stoves will give 1800" in place of 1100°, it is obvions that the furnaces will get around sooner, and without waiting for a change of burden at the tunnel head to bring extra coal to the hearth. The heat absorption caused by a leaky tuyere will chill the hearth and drive the zone of fusion higher up in the furnace. This loss must be supplied, and the calorics lost to the hearth must be regained before good iron can be made. Take another case: A furnace carefully burdened on No. 1 iron, during a spell of damp weather, goes on to No. 2 or No. 3. Heat is lost to the furnace through absorption by the moisture, and less burden must be carried in order to get back on No. 1. When the

Jan 1, 1879

By Tracy C. Jarrett

In 14-karat gold alloys, as in 10-karat gold alloys,3 the addition of such metals as zinc, nickel, copper and silver produces a wide range of physical and chemical properties such as color, hardness, corrosion resistance and melting points. These important factors made gold alloys desirable in the optical work and for jewelry. In 14-karat gold alloys, as well as in 10-karat or 12-karat, it is possible to have two golds of the same color, one of which will corrode more than the other, although it may be harder. Some of these alloys have been investigated by F. E. Carter,' E. M. Wise,= and L. Sterner Rainer.4 In this group of alloys the gold content of 58.3 per cent (14-karat) was held constant, while the copper varied from 36 to 24 per cent. The balance of the alloy consisted of one, two, or three of the metals silver, zinc, and nickel. All the alloys were melted in an induction furnace and cast into an ingot that measured 3 by 1/4 by 3/4 in. The method of determining the melting points, color determinations and acid test have been discussed in previous papers by the author.2, 3 It is necessary to use small test bars (Fig. I). The tensile bars were annealed at 1300oF. for 20 min. and then air-cooled. There being a very marked drop when the yield point was reached, "the drop of the beam" method was used in determining the yield point. Alloys Gold-copper.zilzc A~loys.—Gold-copper-zinc alloys melt, cast, and labricate easily. The low melting points, however, limit their use to some extent. The physical properties of these alloys are not entirely satisfactory. When the ultimate strength is satisfactory, the elongation and reduction of area are too low (Table I). Gold-copper-sinr-nickel A lloys.—In this group of alloys, in which zinc and nickel replace copper in approximately equal parts (Table I), the yield point, hardness, and ultimate strength increase with the increase of zinc and nickel content, while the reduction of area and elongation decrease. The physical properties are desirable, particularly of the white gold alloys. The alloys of this group are not difficult to cast and fabricate, and most of these colors could be used commercially. Gold-copper-nickel A lloys.—Gold-copper-nickel alloys are similar to the gold-copper-zinc and the gold-copper-zinc-nickel alloys. They do, however, possess high yield point, ultimate strength and hardness, somewhat higher than those of the other two groups mentioned (Table I). The difficulty with these alloys is that they fire-crack readily and heavy rolling is necessary between annealings. Being hard to fabricate, many

Jan 1, 1941

By Sherwin F. Kelly

In presenting this brief historical perspective, it is not my purpose to address myself to the geophysicists, to most of whom the story is already well known. My objective is to draw the attention of those who hold the belief that geophysics is something new, typically twentieth century, to the fact that fundamentally, whether it was known by the name of geophysics or not, the science is an ancient and an honorable one. It began many centuries ago, and our modern civilization and its commerce owe a great debt to its founders, who today are likely to be overlooked and their names forgotten. The word "geophysics" means the physics of the earth, and is descriptive of a science that in many ways bears the same relationship to geology that astrophysics does to astronomy. When dealing with distant stars or deeply buried rocks, the experimenter cannot reach them to obtain samples, which can be taken to his laboratory for study. He therefore exhibits the resourcefulness of Mahomet in the mountain episode, and makes the terrestrial globe or the cosmic universe his laboratory, studying the effects of distant bodies on certain "fields of force" which come to him across interstellar space, or through the rocks that make our earth. The application of these- techniques of the physics laboratory to the study of the stars is the science of astrophysics, and to the investigation of the earth is geophysics. Yet the origin of the most valuable contribution to the world's trade and commerce ever made by geophysics remains lost in deep obscurity. Unknown even is the country wherein lived the unsung genius who invented the first geophysical instrument, the mariner's compass! Worse yet, it is not certain whether this invaluable guide of man had its beginnings in Europe or in Asia. A Chinese legend tells of the Emperor Hwang-ti, who attacked his enemy Tchi-yeou on the plains of Tehou-lou in the year 2634 B.C., whereupon the latter magically raised such a fog that the Emperor could not pursue the retreating troops. Not to be outdone, the mighty ruler constructed a chariot that indicated the cardi-

Jan 1, 1940

By C. W. Greenhalgh

THE accuracy with which grade and tonnage of a mineral deposit may be calculated from diamond-drill assays is dependent upon: (I) the reliability of core and sludge samples and (2) the validity of methods used in grade and tonnage calculations. Limitations imposed by drilling and sampling preclude elaborate methods of computation. In adjusting core and sludge assays the importance assigned the core and sludge samples may be based on either the respective weights recovered or the respective volumes represented by each. Only when core and sludge recoveries are poor do discrepancies between adjusted assays calculated by these two methods develop, in which case the "weight" method gives emphasis to the core sample and the "volume" method gives emphasis to the sludge sample. When the sludge suffers classification within the drill hole, the weight method gives more accurate results; when the sludge sample suffers no classification, the volume method gives more accurate results. Any drilling campaign offers a compromise between desired accuracy on the one hand and expediency, limited time, money, or facilities on the other. Since the determination of grade and tonnage is an approximation at best, a proper basis for their computation requires a knowledge of the limitations imposed by all phases of work upon which the calculations depend. A rational basis for coordination of these phases of work requires determination of: (I) the degree of accuracy desired, as a function of the object of examination; (2) the degree of accuracy attainable, as a function of the limitations imposed in the drilling and sampling program; and (3) the validity of method to be used in calculating grade and tonnage from core and sludge assays. This paper presents results of a comparison made between two commonly used methods of adjusting core and sludge assays, the assumptions upon which these methods are based, and the interrelationship of the phases of work upon which these calculations are dependent. OBJECT OF EXAMINATION The purpose of prospecting any mineral deposit is to secure sufficient samples from which ore grade and tonnage may be calculated. Any mine examination, preliminary or formal, has a definite purpose, although its scope may be limited or broad. The type of examination to be conducted is dependent, therefore, upon the reason for instituting the investigation; its scope and thoroughness are directly related to economic considerations. It is highly desirable, therefore, that before starting a drilling campaign a complete understanding of the extent of examination and desired degree of accuracy be determined as a means of simplifying the drilling program and unifying the relative degree of

Jan 1, 1946

By John M. Hartman

(Read at the Wilkes-Barre Meeting, May, 1877.) Two systems are used for heating air in blast-furnace operations I. The double surface system, in which a cast-iron pipe is heated on the outer surface, and, at the same time, heats the blast from its inner surface. This is simple in operation and gives a continuous effect, but is limited by 1100° F. as a maximum temperature of the blast. II. The single surface system, by which large surfaces of fire-brick are heated, and air passed over the heated surface, absorbing the heat and carrying it on to the furnace. This system is more complex than the double surface, as it involves the reversing of the air and gas every hour and a half. The single surface system has two advantages: 1. The blast can be heated to a temperature of 1800° F. 2. The stoves are indestructible. From recent experience it has been found that 1300° F. to 1400° F. is the best average temperature for economy of coal for safe work¬ing. This is equivalent to a saving of 12 to 2 cwt. of coal per ton, of iron over the extreme limit of cast-iron stoves. Independently of this, it is a strong point in favor of this system that the blast can be raised to a temperature of 1800° F. within an hour when the hearth is getting cold. All furnacemen know the value of a hot hearth for quality and quantity of iron. Cooling of a hearth occurs from leaky tuyeres, scaffolds, or heavy burden. When there is not sufficient coal at the tuyeres to seize on the oxy¬gen of the entering air and convert it at once to carbonic oxide, there will not be enough heat to liquefy the cinder. Black cinder and poor iron are the results. The remedy is additional heat from the blast. If the stoves will give 1800° in place of 1100°, it is obvious that the furnaces will get around sooner, and without waiting for a change of burden at the tunnel head to bring extra coal to the hearth. The heat absorption caused by a leaky tuyere will chill the hearth and drive the zone of fusion higher up in the furnace. This loss must be supplied, and the calories lost to the hearth must be regained before good iron can be made. Take another case : A furnace carefully burdened on No. 1 iron, during a spell of damp weather, goes on to No. 2 or No. 3. Heat is lost to the furnace through absorption by the moisture, and less burden must be carried in order to get back on No. 1. When the

Jan 1, 1878

By F. W. McQuiston

INTRODUCTION IDARADO Mining Company's mill and surface plant are at the portal of the Treasury tunnel at elevation 10,625 ft, 12 miles south of Ouray, Colo. In 1943 and 1944 this tunnel was extended in a westerly direction to tap the Black Bear vein, and, together with the recently completed 1100-ft inclined Treasury raise, provides access to the Black Bear mine. In 1945 a 250-ton mill was placed in operation to process development ores containing much needed copper, lead and zinc for war requirements, and to serve as a pilot testing unit for larger scale milling operations. In the years 1902 to 1927 some 329,000 tons of ore were produced from mine workings on the Black Bear vein that extended downward from elevation 12,325 ft at the Black Bear tunnel portal to elevation 11,618 ft, the lowest level of the mine. The ores were taken to the Cascade and Smuggler-Union mills near Telluride over two aerial tramways. Gold bullion, a copper-lead concentrate, and a zinc concentrate were produced. ORES The Black Bear is a compound fissure vein that has undergone several stages of mineralization. The first important stage is represented by complex ores of copper, lead and zinc in a quartz gangue. Precious metal content in this stage is low. The galena is argentiferous and varying amounts of tetrahedrite, freibergite and bornite tend to increase the normal copper content represented in chalcopyrite. The zinc occurs as a true sphalerite with little or no iron. Later re-openings of the fissure took place more or less co-extensively with the successive introduction of (1) abundant quartz gangue containing minor amounts of chalcopyrite, galena and sphalerite; (2) free gold in a fluoritic quartz gangue; and (3) barren, low-grade quartz with minor amounts of pyrite as the only important sulphide. The sulphides show practically no oxidation and little mineralogic intergrowth. Because of the common overlapping of these successive stages of mineralization within a given mining area, considerable dilution of the base-metal content takes place, thus lowering the average mill-head grade. PLANT PRACTICE Metallurgical testing was started shortly after the Black Bear vein was encountered on Treasury tunnel level in 1944. Laboratory tests showed good flotability of the minerals in the ore and indicated an economic separation could be made of the copper, lead and zinc minerals into their respective concentrates. The success of the separation is close reagent control to maintain a balance between promotion and depression of the sulphides. To maintain this balance reagent consumption for the three metal separation is considerably higher than in ordinary lead-zinc flotation.

Jan 1, 1947

By Sherwin Kelly

IN presenting this brief historical perspective, it is not my purpose to address myself to the geophysicists, to most of whom the story is already well known. My objective is to draw the attention of those who hold the belief that geophysics is something new, typically twentieth century, to the fact that fundamentally, whether it was known by the name of geo-physics or not, the science is an ancient and an honorable one. It began many centuries ago, and our modern civilization and its commerce owe a great debt to Its founders, who today are likely to be overlooked and their names forgotten. The word "geophysics" means the physics of the earth, and is descriptive of a science that in many ways bears the same relationship to geology that astrophysics does to astronomy. When dealing with dis-tant stars or deeply buried rocks, the experimenter cannot reach them to obtain samples, which can be taken to his laboratory for study. He therefore exhibits the resourcefulness of Mahomet in the mountain episode, and makes the terrestrial globe or the cosmic universe his labora-tory, studying the effects of distant bodies on certain "fields of force" which come to him across interstellar space, or through the rocks that make our earth. The application of these techniques of the physics laboratory to the study of the stars is the science of astrophysics, and to the investigation of the earth is geophysics. Yet the origin of the most valuable contribution to the world's trade and commerce ever made by geophysics remains lost in deep obscurity. Unknown even is the country wherein lived the unsung genius who invented the first geophysical instrument, the mariner's compass! Worse yet, it is not certain whether this invaluable guide of man had its begin-nings in Europe or in Asia. A Chinese legend tells of the Emperor Hwang-ti, who attacked his enemy Tchi-yeou on the plains of Tchou-lou in the year 2634 B.C., whereupon the latter magically raised such a fog that the Emperor could not pursue the retreating troops. Not to be outdone, the mighty ruler constructed a chariot that indicated the cardi-

Jan 1, 1938

By Sherwin F. Kelly

In presenting this brief historical perspective, it is not my purpose to address myself to the geophysicists, to most of whom the story is already well known. My objective is to draw the attention of those who hold the belief that geophysics is something new, typically twentieth century, to the fact that fundamentally, whether it was known by the name of geophysics or not, the science is an ancient and an honorable one. It began many centuries ago, and our modern civilization and its commerce owe a great debt to its founders, who today are likely to be overlooked and their names forgotten. The word "geophysics" means the physics of the earth, and is descriptive of a science that in many ways bears the same relationship to geology that astrophysics does to astronomy. When dealing with distant stars or deeply buried rocks, the experimenter cannot reach them to obtain samples, which can be taken to his laboratory for study. He therefore exhibits the resourcefulness of Mahomet in the mountain episode, and makes the terrestrial globe or the cosmic universe his laboratory, studying the effects of distant bodies on certain "fields of force" which come to him across interstellar space, or through the rocks that make our earth. The application of these- techniques of the physics laboratory to the study of the stars is the science of astrophysics, and to the investigation of the earth is geophysics. Yet the origin of the most valuable contribution to the world's trade and commerce ever made by geophysics remains lost in deep obscurity. Unknown even is the country wherein lived the unsung genius who invented the first geophysical instrument, the mariner's compass! Worse yet, it is not certain whether this invaluable guide of man had its beginnings in Europe or in Asia. A Chinese legend tells of the Emperor Hwang-ti, who attacked his enemy Tchi-yeou on the plains of Tehou-lou in the year 2634 B.C., whereupon the latter magically raised such a fog that the Emperor could not pursue the retreating troops. Not to be outdone, the mighty ruler constructed a chariot that indicated the cardi-

Jan 1, 1940

By Lucien Eaton

THE accuracy with which detachable bits can be sharpened and gauged by grinding has made possible refinements in design that cannot be attained by forging. This applies particularly to gauging, where accuracy is of the greatest importance. Gauge changes of 1/32 in., and even 1/16 in., are now feasible, whereas 1/16 -in. changes are about the limit in accuracy for forged bits. These small changes in gauge are feasible, however, only with certain fundamental principles of design. Within reasonable limits the depth to which a hole can be drilled is dependent primarily upon the loss in gauge, or diameter, of the bit. In drilling there is always a certain amount of " overdrilling "-the bouncing of the bit in the hole and its rotation wear away the walls-so that the actual diameter of the hole is greater than the diameter of the bit. The amount of this overdrilling depends upon the kind of rock being drilled, and is sometimes sufficient to permit the use of the same diameter of bit for the full depth of the hole. If, for instance, a 1 ¾ -in. diameter bit overdrills 1/32 in. in diameter, and loses 1/64 in. in gauge in drilling 2 ft. of hole, the bottom of the hole is still 1/64 in. larger than the original diameter of the bit, and a new 1 3/4-in. bit can be used to drill the next 2 ft. If, however, the overdrill is less than the loss in gauge, the next bit must be of smaller diameter. The first requisite in reducing loss of gauge in drilling is to have the points and corners of the wings of the bit cut circles of the same diameter, thus producing a reaming surface with continuous bearing on the wall of the hole. The greater the reaming surface, the less the gauge loss that is to be expected. If the reaming surface, however, is too large, it may impede the rotation of the bit through excessive friction. This principle was probably first recognized in the design of the Carr bit (Fig. 1)) a bit with a single cutting edge of wide angle, a definite reaming edge, and a large center hole. The same idea was followed in designing the double-taper cross bits, which are now standard almost everywhere Fig. 2 illustrates a typical double-taper cross bit. The taper from the point of the wing A to a little behind the corner B is 5° and from

Jan 1, 1939

By Tracy C. Jarrett

In 14-karat gold alloys, as in 10-karat gold alloys,3 the addition of such metals as zinc, nickel, copper and silver produces a wide range of physical and chemical properties such as color, hardness, corrosion resistance and melting points. These important factors made gold alloys desirable in the optical work and for jewelry. In 14-karat gold alloys, as well as in 10-karat or 12-karat, it is possible to have two golds of the same color, one of which will corrode more than the other, although it may be harder. Some of these alloys have been investigated by F. E. Carter,' E. M. Wise,= and L. Sterner Rainer.4 In this group of alloys the gold content of 58.3 per cent (14-karat) was held constant, while the copper varied from 36 to 24 per cent. The balance of the alloy consisted of one, two, or three of the metals silver, zinc, and nickel. All the alloys were melted in an induction furnace and cast into an ingot that measured 3 by 1/4 by 3/4 in. The method of determining the melting points, color determinations and acid test have been discussed in previous papers by the author.2, 3 It is necessary to use small test bars (Fig. I). The tensile bars were annealed at 1300oF. for 20 min. and then air-cooled. There being a very marked drop when the yield point was reached, "the drop of the beam" method was used in determining the yield point. Alloys Gold-copper.zilzc A~loys.—Gold-copper-zinc alloys melt, cast, and labricate easily. The low melting points, however, limit their use to some extent. The physical properties of these alloys are not entirely satisfactory. When the ultimate strength is satisfactory, the elongation and reduction of area are too low (Table I). Gold-copper-sinr-nickel A lloys.—In this group of alloys, in which zinc and nickel replace copper in approximately equal parts (Table I), the yield point, hardness, and ultimate strength increase with the increase of zinc and nickel content, while the reduction of area and elongation decrease. The physical properties are desirable, particularly of the white gold alloys. The alloys of this group are not difficult to cast and fabricate, and most of these colors could be used commercially. Gold-copper-nickel A lloys.—Gold-copper-nickel alloys are similar to the gold-copper-zinc and the gold-copper-zinc-nickel alloys. They do, however, possess high yield point, ultimate strength and hardness, somewhat higher than those of the other two groups mentioned (Table I). The difficulty with these alloys is that they fire-crack readily and heavy rolling is necessary between annealings. Being hard to fabricate, many

Jan 1, 1941

By Hermann Wedding

I ask your permission to speak about a matter which is not of a specifically scientific nature, but more of a general—I might even say of an international—nature, and the international character which this city now presents must be my justification for introducing it. The Germans, very often, are thought to be an exceedingly warlike people, but I come to-day in the capacity of a peacemaker. Our German language is an original language; it is, therefore, a language in which it is impossible to change the meaning of a word at will. It may be, perhaps, easier in a combined language, as the English, to associate and to exchange meanings. Now, a word which we hear a great deal at the present day, is "Stahl," in English, "steel." This word means, in the German language, a substance which can be hardened. As the German literature, in relation to metallurgy, is the oldest of the modern world, this circumstance may give the German a right to ask for consideration. But I think, now, when the four languages, German, Swedish, French, and English, compete in rich metallurgical literature, it is very necessary to have uniformity in the nomenclature of iron, which would prove not only useful for science, but equally so for trade. For that purpose I propose to make the divisions of iron so that the word steel shall comprise a subdivision and not a primary division as formerly. Nature furnishes us iron mostly in the state of oxides, and if in any other condition, we must convert the ore into oxide before we can make iron. The oxides are always mixed with certain earthy substances called rock or gangue. The extraction of iron involves, therefore, the twofold process of the reduction of the iron, and imparting to it the amount of carbon necessary for technical purposes, and the separation of the reduced and carburized iron from the gangue. The reduction is always effected by carbon or carbonaceous substances (coke, anthracite, carbonic oxide, etc.), and the result is, according to the degree of heat employed, either malleable iron or a non-malleable iron. The process of malting malleable iron in this way is called, generally, the direct process—in German, Rennarbeit. It produces the iron in a solid state with a fluid cinder. By this process our ancestors made all their iron, and it has been revived in various ways in modern times up to the process of Mr. Blair, so far as I know, always without commercial success. The

By A. Karim, T. G. Langdon, C. Y. Cheng, J. E. Dorn

The effect of changes in temperature and stress on the creep behavior of Fe-4 pct Si was investigated over the temperature range from 650° to 1175K Over the temperature range of 799° to 110l°K, the shear strain rate, ?', obeys the relationship: where K is a constant, 7 the applied shear stress, G the shear modulus, g the free activation energy for diflusion, R the gas constant, and T the absolute temperature. The results strongly suggest that the creep in this alloy is controlled by a dislocation climb mechanism. In a recent investigation, Ishida, Cheng, and Dorn1 observed that the apparent activation energy for creep of a! Fe from 480" to 775°K corresponded to that for self-diffusion. Over the magnetic transformation range (775" to 1045"K), the apparent activation energy for creep increased steeply with increasing temperature in agreement with the known decrease in the free activation energy for self-diffusion. Passing through the Curie temperature, the apparent activation energy decreased abruptly following which it then increased mildly as the temperature further increased. Inasmuch as the apparent activation energy for creep of a! Fe below the Curie transformation range of temperatures appeared to decrease with increasing values of the stress, the data were analyzed in terms of a model based on the nonconservative motion of jogged screw dislocations. But since the observed creep rate was much higher than that which could be accounted for on the basis of usual models, the authors found it necessary to assume that pipe diffusion became significant over the lower temperature range. Furthermore, the abnormally high activation energy for creep above the Curie temperature was attributed to grain boundary migration which became prevalent in this temperature range. It was thought that a number of the interesting issues that arose in the creep of a Fe might be resolved by investigating the creep of Fe-4 pct Si alloy: This alloy has about the same Curie range and therefore should give creep results that closely parallel those for a Fe and in this way provide comparable data for analysis of creep mechanisms. Furthermore, it can be annealed at higher temperatures which could provide some stabilization against grain boundary migration. In addition, it might serve to illustrate the possible effects of short-range ordering on creep.

Jan 1, 1969

By Fred H. Kan

The production of petroleum in Venezuela during 1931 was approximately 118,767,000 bbl., a decrease of 18,904,000 bbl., or 13.7 per cent, compared with the previous year. This is the first break in production, which has risen steadily since 1920, and is attributable to restriction of output and drilling operations, in harmony with lessened demand, rather than to any real decline in potential production. Venezuela ranked third among the world's producers, having lost second place to Russia. The Bolivar coastal fields, which were extended approximately 14 miles southward during the year, continued to supply most of the oil. La Concepcion, Los Manueles and Quiriquire all showed marked increases. A new field of light oil was discovered on the north coast near Puerto Cumarebo, State of Falcon. Exports declined 15.7 per cent, from 137,377,000 bbl. in 1930 to about 115,800,000 bbl. in 1931. Crude oil in storage at the end of the year amounted to 7,450,000 bbl., a decrease of 2,150,000 as compared with 1930. Tankage utilized is about 40 per cent of the available space. A drastic decline in drilling activity reduced the number of wells completed in producing areas from 401 in 1930 to 116 in 1931. Only three wells were drilled in the Lagunillas field proper, but, the amount of closed-in production and proven acreage gave assurance of a satisfactory potential output. Of the 1580 wells drilled to the close of 1931 in the producing areas of the Bolivar Coast, 631 were active and 853 were closed in; 96 had been abandoned. The status of the active wells at the end of 1931 was as follows: flowing, 331; pumping, 99; gas-air lift, 201. Producing wells closed in numbered 452; workovers, 8; totally inactive, 393. Lago Petroleum Corp. and Venezuela Gulf Oil Co. placed in operation the first units of their electric power plants, the former at Punta Gorda and the latter at Las Morochas, and are replacing steam power in their operations as rapidly as possible. Compressor stations were also installed for use in connection with air-gas lift operations. A considerable volume of gas was treated in gasoline extraction plants, the tail gas being recom-pressed and utilized together with natural high-pressure gas, for stimulation of production.

Jan 1, 1932

By G. Mempel, D. C. Yang, D. W. Fuerstenau

This paper describes details of the design and operation of a batch tumbling mill which has been used for a number of years in the laboratories at the University of California. In order that the energy expended for grinding can be measured accurately, this specially constructed laboratory mill has sensitive torque measuring apparatus. Torque measurements are given for a variety of conditions with this particular mill. In recent years, there have been numerous and fairly extensive investigations of grinding in tumbling mills reported in the literature. Most of these investigations have been carried out in mills with widely differing dimensions. As a result, comparison of results obtained from various investigations has been virtually impossible. If similar mills were used by different investigators, a considerable step forward would be taken in grinding research. A specially constructed laboratory mill with sensitive torque measuring apparatus has been used for a number of years in the laboratories of the University of California. The purpose of this paper is to describe details of the design and operation of this batch tumbling mill so that other researchers, who might be interested in obtaining data for intercomparison, could construct a similar device for their own research. Furthermore, since torque instrumentation is quite expensive, torque measurements are given for a variety of conditions with this particular mill so that those who may not wish to duplicate torque measuring apparatus can make reasonably accurate torque estimates merely by duplicating the loading conditions. It is not intended in this paper to present theoretical derivations of energy consumption in ball mills. This has been done e1sewhere.l-3 CONSTRUCTION OF THE MILL In order to eliminate rust problems with wet grinding, the mill and grinding media are made of stainless steel. The mill shell was rolled from 1/2-in. steel plate. The inside dimensions are 10-in. diam and 11-1/2-in. length, similar to the mill used by Charles.4 It is equipped with eight lifter bars (1/4-in. in height) whose dimensions are given in Fig. 1. The lifter bars have been bolted into the shell so they can be removed for experiments without lifter bars; however, all data presented here are for the mill with lifters. One end of the mill is fitted with two 1/2-in. diam removable plugs for filling the mill with liquid for wet grinding experiments. The mill is mounted on ball bearing rollers as can be seen in Fig. 2. The pillow block bearings are single-row self-aligning sealed ball bearings with 1-1/4 in. hole diam. The bearings supporting the mill shell are single row sealed ball bearings with

Jan 1, 1968

The Inspiration ore body was discovered in 1904, but a 50 -ton mill which was installed to treat the disseminated copper ore promptly failed. The original Inspiration Company then gave way to another, backed by W. B. Thompson, which found 40 million tons of ore. Control then passed to Anaconda and Dr. Louis Ricketts took charge as consulting engineer. He abandoned the mill which had been partially built (to the horror of the stockholders, according to Ira Joralemon) and spent a year and a million dollars experimenting with flotation. The first large copper flotation plant was then built and recovered 50% more copper than had previous gravity mills. It, of course, was highly successful and became the forerunner of modern flotation plants. Inspiration is distinctive as the first fully integrated copper operation in the United States. Three open pits supply sulfide ore to the concentrator and mixed oxide and sulfide ore to a vat leaching and electrowinning operation with leached ore also being sent to the concentrator. In addition, dump leaching supplies pregnant solution for scrap iron precipitation. Inspiration has recently constructed an electric furnace smelter and also operates a continuous casting and rod plant. The new primary 54 in. by 74 in. crusher was completed in May of 1972 and replaced an older unit which was in the way of the open pit development. It is of an unusual circular silo design, which permits dumping 0 from two positions at 90 from each other. One dumping position is in line with the spider, while the other one is at right angles to it. A box girder splitter bar hung from the dump pocket slopes downward from the second dump point, across the spider cap, and rests on the pocket bottom. This splitter was not installed to protect the spider but was to aid in distributing wet ore being dumped from that position to both sides of the spider. Any large amount of wet ore delivered to one side of the spider would pack in the crusher cavity. The round front wall of the 18 ft (5.5 m) deep pocket is unlined except for light steel protection at the top, while the straight back wall is lined with vertically positioned railroad rails. Water for dust suppression is sprayed into the pocket through a cluster of 3/8 in. (9.5 mm) nozzles at the back of the pocket. About 5 gpm (19 lpm) of water are mixed with 90 psi (620 kPa) air upstream of the nozzles to produce a fog which is effective in dust control. The 54 in. Allis -Chalmers gyratory is placed mostly within one quadrant of the circular enclosure to permit placement of the apron feeder on the lowest level in the proper position to transfer crushed ore to the

Jan 1, 1978

By L. W. Page

PrEvious to the introduction of the motor vehicle the broken stone or macadam' road met the conditions of rural horse-drawn traffic better than any other type of road, but under fast motor traffic it has been proved to be quite unsatisfactory, and necessitates high maintenance charges. Such a road depends for its success upon the fact that the rock dust fills the voids between the stones and acts as a cement or binder. Under ideal conditions it should be constructed of rock so suited to the volume and character of horse traffic that only enough fine dust is worn from the stones of which the road is composed to take the place of that carried off by wind and rain; and when these conditions are met, the fine dust resulting from the wear of traffic forms with the stone a smooth, impervious shell, shedding the surface water and protecting the foundation. With increase in the number and speed of motor vehicles, however, it was soon found that the cost of maintenance also increased, until at the present day highway engineers consider the old method of constructing and maintaining broken-stone roads increasingly inadequate, and are introducing every known type of binding material other than rock dust to cement the stone together. Among the most prominent types of products in use are those produced from our various petroleums. That the value of modern methods of road preservation was appreciated in this country much earlier than we have been accustomed to believe is demonstrated by the recent revival of an old patent which was granted to one John Martineau, of Elbridge, N. Y., in 1834. Petroleum had, of course, not been discovered at that time, but he claims as his invention and improvement "The application of tar, turpentine, or any of that class of tenacious, cohesive substances, reduced before use to a fluid state, and that state used as a cement, to apply to, and combine with sand, gravel, pebbles, and pulverized stone, such as is used for a Mc-Adam road, or cobble stone, the interstices of coarser material being in all cases filled,'as well as may be, with sand and gravel and cemented with tar or turpentine, to form the wearing face or surface of streets,

Jan 1, 1915

By Reuben B. Ellestad, Fremont F. Clarke

Lithium chemical plant extraction methods are discussed with reference to 1) base exchange with alkali sulphates; 2) processing based on roasting with lime; 3) miscellaneous methods; and 4) application of the Lithium Corp. process to extraction of lithium from run-of-mine, low grade spodumene ore, or concentrates. IN the early days of the lithium industry most of the production was from lepidolite, zinnwaldite, and amblygonite. Nearly all the early extraction processes described in the literature involve heating the finely ground mineral with sulphuric or hydrochloric acid. On subsequent water leaching most of the bases present in the mineral (especially aluminum) are dissolved as sulphates. As a result, the leach solution required extensive chemical purification before the lithium could be precipitated as carbonate. Following the remarkable growth of the lithium industry to its present size, zinnwaldite and amblygonite ores must be considered of minor importance only. Attention is now focused on spodumene, abundant enough in North America to be a major source of supply, and there are important supplies of lepidolite and petalite in Africa. The extraction processes described below all apply to spodumene, although several will also operate on other lithium minerals, such as petalite. Base Exchange with Alkali Sulphates: A distinct advance was made with the disclosures of Wadman and von Girsewalt. In these methods the finely ground silicate ore (spodumene or lepidolite) is intimately mixed with an excess of alkali sulphate (usually K2SO4) in at least a 1 to 1 proportion, and the mixture was heated to a relatively high temperature. Base exchange results, with the formation of lithium sulphate. A water leach dissolves the lithium sulphate, together with the excess potassium sulphate. Successful operation of this type of process requires very thorough grinding and mixing, as well as careful temperature control. The use of K2SO4 is objectionable from cost considerations since purification of lithium carbonate requires the use of potassium carbonate, if the K2SO4 is to be recovered and recycled. The lower solubility of K2SO4 as compared with Na2S04 is also objectionable, since it limits the concentration of the Li2SO4 solution to be precipitated by K2SO4. Early laboratory-scale investigation of this process by Lithium Corp. was not encouraging. Other related base exchange processes are those of Lindblad, Wallden, and Sivander3 and Sivander, Gard, Villestad, and Wallen4. The former covers the reaction of lithium silicate minerals with a sodium sulphate solution, at 100" to 300°C (under pressure), while the latter involves the extraction of silicate minerals with molten sodium sulphate. Both these processes would seem to be difficult and expensive to operate.

Jan 1, 1956

HAVING promised you to write concerning the nature of ores in particular, I must tell you some general facts, especially those concerning the places, kinds, and manner of their existence as well as the tools which are used. However, you must know that according to good investigators these ores are found in many parts of the world. They show themselves almost like the veins of blood in the bodies of animals, or the branches of trees spread out in different directions. Indeed, careful investigators of minerals, wishing to show by analogy how ores are located in mountains, have drawn a large tree with many branches, planted in the middle of the base of a mountain. From its principal trunk extend various branches, some thick, some slender, exactly like real trees in mature forests. They think that these grow and enlarge continually and draw themselves toward the sky, ever converting into their own nature the most disposed adjacent materials so that finally the tips arrive at the summit of the mountain and emerge with clear sign, sending forth, in place of leaves and blossoms, blue or green fumosities,* marcasites with small veins of heavy mineral, or other composition of tinctures. From these things, when they are found, it is possible to make certain inference that such a mountain contains ores, and as the signs are more or less, so are the minerals plentiful and rich or poor. For this reason the prospectors for these things take heart according to the manifestations that they find, and with hope and certainty of profit they take all possible pains to mine with skill and expense those things that the signs have indicated. Often there are ores of such a kind and quality that they raise a man in wealth to the skies. For this reason men penetrate with eyes of appraisal and judgment within the mountains and see almost exactly the places where there is ore and the

Jan 1, 1942