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By George Smith

THE discussion of production control at the Insti-tute's annual meeting was profitable in that it started some thinking. One pertinent question there raised was how the opening of new mines, whose now unneeded output would inevitably react on prices, could be postponed until the market was ready to ab-sorb their output. In transportation some restraint is being exercised on building new and unneeded fa-cilities, but in production no general solution of the problem has been offered. Yet in a special field of new development of increasing importance a quick and easy solution has been suggested. I refer to the leasing of mineral deposits on the public domain. The report of the United States Coal Commission says: "In its possession of approximately 60,000,000 acres of public coal lands the Federal Government has its own responsibility in restraining overdevelopment. The Department of the Interior, which has control of these lands under the leasing law, construes the law as giving the department no discretionary right to refuse applications for leases regularly made by qualified citizens or corporations for coal deposits on the pub-lic domain. It presumes, that the applicant believes there is a need for an additional coal mine in his local-ity and expects to find a market for the coal produced. Overdevelopment, however, is a fact in the West as well as in the East, and wherever present involves needless investment and excessive costs of operation. Plainly, the leasing law should be so amended as to give the executive department full discretion in its approval of the opening of a new coal mine on the, public domain, making that approval contingent on the showing that the new mine would serve the in-terest of the consuming public." A similar view of the Federal Government's re-sponsibility in restraining overdevelopment of its oil lands has been presented by the Federal Oil Conser-vation Board. The leasing law vests little or no dis-cretion in the Secretary of the Interior, who must grant a lease to a qualified applicant regardless of any obvious country-wide condition of surplus produc-tion. This wide-open invitation to exploit and dissi-pate the people's own oil resources could be restricted by simple legislation, although as remarked by the board, such a legislative remedy for a plain economic ailment "does not evoke popular support when its purpose is avowedly to put the brakes on development of natural resources."

Jan 5, 1928

By F. C. Miller

The metallurgical fuel of Colorado, Utah, and New Mexico has been a Veiny tardy member in the caravan of western industrial progress. The history of western coke has naturally been closely related to the development of the metallurgy of iron and steel and the precious metals, in the State of Colorado. It was at Leadville, with a population of 300 in 1877, that the Sentinel was published by Richard S. Allen. The Sentinel gave very full accounts of the various mineral discoveries at the new town of Leadville, which found their way to the more widely circulated journals of the East, and attracted the attention of many people. At the close of 1878, a census slowed a total of 5040 persons. The first smelter was established in 1877, at Malta, two miles from Leadville, by A. R. Meyer, but was not successful. It was succeeded by the Harrison Reduction Works, in 1878. The La Plata began with one furnace in June, 1878, and in 1879 had four furnaces in active operation. These furnaces used charcoal for fuel, and, because of hot tops, suffered a tremendous loss in lead and silver. This difficulty was overcome by the erection of 50 single-bank 10-ft. beehive ovens at Crested Butte, Colo., in 1880. The slack coal sent to these ovens was very pure, and yielded a coke carrying as little as 4.5 per cent. ash. Among the pioneers in the Leadville district were Grant, Eddy, James, Billings, Eiler, and Dickson. To these men the West owes the present expansion of its mining industry, and the erection of metallurgical processes for the treatment of precious metals. On Mar. 1, 1876, Pueblo was connected to the Atchison, Topeka & Sank Fe by the Pueblo & Arkansas Valley branch. The first smelter was erected in Pueblo by Mather and Geist. This modest plant grew into the immense Pueblo Smelting and Refining Co., now a part of the American Smelting and Refining Co. Coke for these small furnaces was made from unwashed Engleville coal, in 186 single-bank 12-ft. ovens at El Moro, in the Trinidad district, and it was not uncommon for the percentage of ash to exceed the percentage of fixed carbon in the coke. On Jan. 23, 1880, the Colorado Improvement Co. consolidated

Jan 1, 1920

By E. V. Foran

AMONG the many newer disclosures that have accompanied the petroleum industry's progressively deeper exploratory drilling is the increased frequency with which the operators are encountering reservoirs of which the products at the time of discovery exist wholly or predomi-nantly in the gas phase. The popular term "distillate pool" is most often used within the industry when referring to this type of reservoir, and in this paper the term is used in that sense. These pools have been observed in many different surroundings. In some places the entire reservoir is filled with the wet gas containing its water-white condensible products in the gas phase but apparently with no dark oil or other hydrocarbon liquids in the reservoir. The 8200-ft. horizon in the Big Lake field in West Texas is a good example of this type. At other places the wet, or distillate-bearing, gas may form a large gas cap directly overlying and in contact with an extensive reserve of dark oil. Oklahoma City, Kettleman Hills, the 8500-ft. horizon in the Big Lake field, and many others are examples of this type. There are also many places in which the wet distillate-bearing gas fills nearly the entire reservoir space, while the dark oil occupies only a narrow, bandlike zone, which marks the boundary of the reservoir along its lowest productive contour. The heavier components of these deep pool gases are generally water white in color, a large portion of which are condensible in a conventional oil and gas separator, when operated under pressures of the order of 400 to 800 lb. per sq. in. Although the water-white products recovered in the separator sometimes have end points of 650° F. and higher on standard Engler distillation, they occur only in the gas phase in the reservoir. It is entirely possible that even some small amounts of dark colored reservoir components may occur in the gas phase when the temperature is 300° F. and pressures exceed 6000 lb. per sq. in. Close approaches to these conditions have been encountered in the deepest producing wells. The condensible content of the deep reservoir gases of the many pools that have been tested or produced to date shows a wide variation in both condensible content, per 1000 cu. ft. of gas, and physical character.

Jan 1, 1939

By C. P. Parsons

To properly account for the various characteristics of drilling muds obtained in different areas and geological horizons, it is necessary to study the composition of the mud from a chemical and physical standpoint as determined by the proportions and activities of the various solid contituents that are present in various states of division. Briefly summarized, science teaches that there are three states of division into which these solid constituents or particles may be grouped: namely, the suspended state, the individual particles of which are known as suspensoids; the colloidal state, in which the individual particles are termed colloids; and the crystalloidal state, wherein the individual particles are held in true solution and are termed crystalloids. The suspended state is one wherein the particles are fairly large and are present as molecular complexes, having none of the properties of colloids or crystalloids. Since matter varies in physical character and in chemical activities with its state of division, these coarser suspensoids do not themselves materially affect the physical or chemical properties of the solution in which they are suspended. On the other hand, they are distinctly detrimental in drilling muds and it is desirable that they be removed. Under the general classification of suspensoids are included sand, gravel and cuttings which contribute nothing to the colloidal stability or other desirable properties of the drilling fluid. As the state of division approaches but does not reach a molecular simplification, the term "colloidal state" is used in describing this condition. The colloidal state arises when one form of matter is in a very fine state of division and is distributed through a second phase. The material in the finely divided state is called the dispersed phase, while the liquid in which it is dispersed is called the dispersive phase. These particles of matter are in a colloidal state and will not settle out from the dispersive phase so long as colloidal conditions are stable. Moreover, they exhibit the property of having an oscillating movement around a central position in solution (the Brownian movement). In the third state of division, the crystalloidal state, the individual particles are held in true solution and are usually present as single molecules or ions. In a drilling fluid the water content of the fluid contains

Jan 1, 1931

By Norman D. Fitzgerald

The purpose of this paper is to analyze the behavior of oil securities during the six-year period January 1932 through December 1937. This period was selected because of its varied character. It includes the depths of the depression, the broad and spasmodic recovery, and the recession collapse. The first part of the analysis is devoted to the correlation of a number of economic factors with an index of 13 oil stocks. The second part is a comparison of the different,ial behavior of 6 oil stocks. The relationships developed here are only a few of many that might be considered in a complete analysis. The stock market is regarded as a barometer of business confidence and as such exerts an important influence upon corporate policies, particularly upon industrial expansion. The complex and continuously changing nature of its price structure, the ebb and flow of influences and the effects of impacts require dynamic rather than static analysis. When treated in this way, many of the important fluctuations in market prices and changes in the relationships between securities appear quite logical. The market for oil securities has varied widely in recent years. The Standard Statistics index of 13 oil stocks made a bull market peak of 166.7 in September 1929. The collapse of the boom and the ensuing bear market finally carried the index down to a low of 36.4 in June 1932. From this point oil stocks made an irregular recovery; they reached a top at 139.7 in March 1937, and after maintaining this approximate level through August, declined precipitously to 93.3 in December 1937. The prices of these 13 oil stocks have gone up and down under the influence of numberless variables. These variables are of two kinds, those external to the industry, and those that are solely due to its internal condition. The external factors are political, social, and economic, both domestic and foreign. These are the influences that induce the ebb and flow of all prices in general and security prices in particular. Among the internal factors are the regulation of industry, the development of new reserves and processes, and the disequilibrium due to lack of balance between supply and demand. Some of the simpler relationships are examined in this paper.

Jan 1, 1938

By E. V. Foran

Among the many newer disclosures that have accompanied the petroleum industry's progressively deeper exploratory drilling is the increased frequency with which the operators are encountering reservoirs of which the products at the time of discovery exist wholly or predominantly in the gas phase. The popular term "distillate pool" is most often used within the industry when referring to this type of reservoir, and in this paper the term is used in that sense. These pools have been observed in many different surroundings. In some places the entire reservoir is filled with the wet gas containing its water-white condensible products in the gas phase but apparently with no dark oil or other hydrocarbon liquids in the reservoir. The 8200-ft. horizon in the Big Lake field in West Texas is a good example of this type. At other places the wet, or distillate-bearing, gas may form a large gas cap directly overlying and in contact with an extensive reserve of dark oil. Oklahoma City, Kettleman Hills, the 8500-ft. horizon in the Big Lake field, and many others are examples of this type. There are also many places in which the wet distillate-bearing gas fills nearly the entire reservoir space, while the dark oil occupies only a narrow, bandlike zone, which marks the boundary of the reservoir along its lowest productive contour. The heavier components of these deep pool gases are generally water white in color, a large portion of which are condensible in a conventional oil and gas separator, when operated under pressures of the order of 400 to 800 Ib. per sq. in. Although the water-white products recovered in the separator sometimes have end points of 650" F. and higher on standard Engler distillation, they occur only in the gas phase in the reservoir. It is entirely possible that even some small amounts of dark colored reservoir components may occur in the gas phase when the temperature is 300" F. and pressures exceed 6000 Ib. per sq. in. Close approaches to these conditions have been encountered in the deepest producing wells. The condensible content of the deep reservoir gases of the many pools that have been tested or produced to date shows a wide variation in both condensible content, per 1000 cu. ft. of gas, and physical character.

Jan 1, 1939

By O. C. Ralston

The use of copper sulfate for improving the flotation behavior of sphalerite is probably at least 15 years old. The original discovery of its activating influence is somewhat obscure. The story goes that in the mill at Mascot, Tenn., its favorable action was discovered by accident, early in 1914, as follows: The original laboratory test work on a sphalerite ore gave favorable flotation results, but after a mill had been built the flotation concentration of the ore was very unsatisfactory. In diagnosing the probable reasons, one fact pointed out was that the laboratory test machine had been constructed of bronze whereas the commercial machine allowed pulp to come in contact only with wood and iron. A plate of sheet copper was hung in the flotation machine and results immediately improved. At first fanciful explanations of electrolytic and electrostatic behavior were given credence, but when the copper plate was removed and a small amount of copper sulfate substituted in the pulp an even more favorable result was obtained. Toward the end of 1914 copper sulfate was also adopted in the acid flotation circuit of the Butte and Superior Copper Co. Just who is responsible for the original discovery the present writers do not know. It seems strange that in that era of flotation litigation this discovery was not patented. While for pragmatic purposes it [nay be sufficient to know that the mere addition of copper compounds to a flotation pulp is sufficient to activate the flotation of the sphalerite, for scientific purposes it is quite desirable to know more about how the action takes place. It is the purpose of this paper to present certain evidence dealing with the mechanism of the beneficial effect. The description of the effect as activation in contradistinction to depression is now common in both the English and German languages. It makes no assumptions as to whether the zinc sulfide surfaces have been filmed with copper compounds. In fact, the principal differences of opinion expressed in the literature deal with whether there is an actual formation of CuS (or even Cu2S) on the surface of the sphalerite. Activation of sphalerite takes place in alkaline, neutral or weakly acid solutions and whereas the present day flotation of sphalerite is usually in ah alkaline solution, the early use of copper sulfate was in a sulfate solution.

Jan 1, 1930

By E. V. Foran

Among the many newer disclosures that have accompanied the petroleum industry's progressively deeper exploratory drilling is the increased frequency with which the operators are encountering reservoirs of which the products at the time of discovery exist wholly or predominantly in the gas phase. The popular term "distillate pool" is most often used within the industry when referring to this type of reservoir, and in this paper the term is used in that sense. These pools have been observed in many different surroundings. In some places the entire reservoir is filled with the wet gas containing its water-white condensible products in the gas phase but apparently with no dark oil or other hydrocarbon liquids in the reservoir. The 8200-ft. horizon in the Big Lake field in West Texas is a good example of this type. At other places the wet, or distillate-bearing, gas may form a large gas cap directly overlying and in contact with an extensive reserve of dark oil. Oklahoma City, Kettleman Hills, the 8500-ft. horizon in the Big Lake field, and many others are examples of this type. There are also many places in which the wet distillate-bearing gas fills nearly the entire reservoir space, while the dark oil occupies only a narrow, bandlike zone, which marks the boundary of the reservoir along its lowest productive contour. The heavier components of these deep pool gases are generally water white in color, a large portion of which are condensible in a conventional oil and gas separator, when operated under pressures of the order of 400 to 800 Ib. per sq. in. Although the water-white products recovered in the separator sometimes have end points of 650" F. and higher on standard Engler distillation, they occur only in the gas phase in the reservoir. It is entirely possible that even some small amounts of dark colored reservoir components may occur in the gas phase when the temperature is 300" F. and pressures exceed 6000 Ib. per sq. in. Close approaches to these conditions have been encountered in the deepest producing wells. The condensible content of the deep reservoir gases of the many pools that have been tested or produced to date shows a wide variation in both condensible content, per 1000 cu. ft. of gas, and physical character.

Jan 1, 1939

By Felix B. Shay

The Agua Fria mine is in eastern Honduras at Lat. 140" 06' N., Long. 86" 36' W. Danli, the seat of the local municipal government, is the nearest town. The property is approximately 44 miles east of Tegucigalpa, the terminus of a truck road from the Pacific coast. The mine lies at an altitude of 3300 ft. with surrounding elevations as high as 6000 feet. For 20 years the oxidized croppings of the Agua Fria vein had been worked intermittently when in 1927 an attempt was made to open the property. A shaft was sunk 300 ft. and considerable ore was blocked out, but before a mill could be installed financial difficulties arose and the mine reverted to the original owners. Erle Y. Halliburton, of Los Angeles, purchased the property in 1934. At that time a careful consideration of all factors involved showed that air transport was the only practical method of moving the equipment and machinery necessary to commence production. The other alternative was by muleback, which required sectionalizing all equipment to a maximum load of 200 lb., and during the rainy season this type of freighting was subject to serious delays. It was decided to purchase a trimotor Ford powered by three Pratt and Whitney Wasp B motors developing 400 hp. each. There were several reasons for the choice: (1) this type of plane was available at a reasonable price, owing to its replacement by faster models on most of the airlines in the United States; (2) the ship was capable of carrying a pay load of 3000 Ib. over the required distance; (3) since this airplane had been widely used there would be no difficulty in securing competent personnel or in purchasing spare parts. It was necessary to rebuild the plane for cargo servicc. The windows were removed and the fuselage was entirely covered. A hatch was cut in the top of the fuselage to receive heavy crane loads and pieces of freight that were too large or too long to go through the rear door. The seats were removed and the interior of the plane was lined with Duralumin sheets. A heavy-duty landing gear was installed and the floor was reinforced. The nearest site for an airport was two miles north of the mine. The necessary grading was done by a small track-type tractor with a wheeled grader, which was brought in overland. Six weeks was required for bring-

Jan 1, 1940

By M. B. Standing, D. L. Katz

Equilibrium data are reported on the composition and densities of coexisting vapor and liquid phases as a function of Pressure and temperature for four hydrocarbon systems prepared from crude oil and natural gas. The data were observed over a range of pressures from 1000 to 8220 Ib. per sq. in. and at temperatures ranging from 35' to 250°F. The compositions of the hydrocarbon systems were such that the critical temperatures of the mixtures were lower than the range of the investigation. Under these conditions, it is shown that the composition of the systems has a marked effect upon both the absolute value of the equilibrium constants and the change of the constants with pressure for the several components comprising the system. From weight-balance considerations, it has been possible to construct the partial phase diagram of a mixture of a 49.9" A.P.I. crude oil and natural gas having a gas-oil ratio of 3660 cu. ft. per barrel. Descriptions of the apparatus used, the analytical procedure, the material used, and the equilibrium measurements are included. A knowledge of the physical behavior of naturally occurring hydrocarbon mixtures is fundamental to the treatment of many problems in the production, transportation and rehing of petroleum. The recent discoveries of pools having formation pressures up to 7500 lb. per sq. in. and higher, and the development of full-scale equipment to operate at pressures of 5000 lb. per sq. in. or more have greatly increased the need for knowledge of the composition, temperature, pressure and density relationships of coexisting vapor and liquid hydrocarbon phases. The following paper presents the results of investigations upon 22 mixtures of natural gas and crude oil of known com~o~itio~ that had been brought to equilibrium under controlled conditions of temperature and pressure. Data are presented upon the densities and compositions of the coexisting vapor and liquid phases for four different systems containing hydrocarbon material having boiling points from minus 2 5S°F. to well over I000 F. The data were observed Over a pressure range from Iooo Ib. per Sq. in to 8220 lb. Per sq. in. and a temperature range from 35' to 2 50°F. The accepted method of computing the physical relationship between two coexisting phases of a hydrocarbon mixture is by use of the "equilibrium constant" K as proposed by Souders, Selheimer, and Brown. definition,

Jan 1, 1944

By Felix B. Shay

The Agua Fria mine is in eastern Honduras at Lat. 140" 06' N., Long. 86" 36' W. Danli, the seat of the local municipal government, is the nearest town. The property is approximately 44 miles east of Tegucigalpa, the terminus of a truck road from the Pacific coast. The mine lies at an altitude of 3300 ft. with surrounding elevations as high as 6000 feet. For 20 years the oxidized croppings of the Agua Fria vein had been worked intermittently when in 1927 an attempt was made to open the property. A shaft was sunk 300 ft. and considerable ore was blocked out, but before a mill could be installed financial difficulties arose and the mine reverted to the original owners. Erle Y. Halliburton, of Los Angeles, purchased the property in 1934. At that time a careful consideration of all factors involved showed that air transport was the only practical method of moving the equipment and machinery necessary to commence production. The other alternative was by muleback, which required sectionalizing all equipment to a maximum load of 200 lb., and during the rainy season this type of freighting was subject to serious delays. It was decided to purchase a trimotor Ford powered by three Pratt and Whitney Wasp B motors developing 400 hp. each. There were several reasons for the choice: (1) this type of plane was available at a reasonable price, owing to its replacement by faster models on most of the airlines in the United States; (2) the ship was capable of carrying a pay load of 3000 Ib. over the required distance; (3) since this airplane had been widely used there would be no difficulty in securing competent personnel or in purchasing spare parts. It was necessary to rebuild the plane for cargo servicc. The windows were removed and the fuselage was entirely covered. A hatch was cut in the top of the fuselage to receive heavy crane loads and pieces of freight that were too large or too long to go through the rear door. The seats were removed and the interior of the plane was lined with Duralumin sheets. A heavy-duty landing gear was installed and the floor was reinforced. The nearest site for an airport was two miles north of the mine. The necessary grading was done by a small track-type tractor with a wheeled grader, which was brought in overland. Six weeks was required for bring-

Jan 1, 1940

By H. M. Howe

(Read at. the Lake George Meeting, October, 1878.) MANY direct processes have been proposed for the treatment of oxidized ores of copper by reducing the copper oxide to the metallic state, and by separating it from its impurities by a subsequent fusion. The radical objection common to all the methods which have come to my notice, except those in which sulphur plays the prominent part, is that the very deoxidizing agent which effects the reduction of the copper oxide, inevitably reduces at the same time a very considerable part, if not the whole, of the iron which almost invariably accompanies copper in its ores. The result is that, when the ore is subsequently fused, a very great quantity of the already reduced iron separates from the slag along with the copper, alloying with it, and necessitating costly subsequent operations for its separation. Thus, at Perm, in the Urals,* the product of the fusion of ferruginous copper oxides is a mixture of one hundred and fifty-five parts of highly cupriferous pig iron with two hundred and five parts of very impure and ferruginous black copper, containing some 10 per cent. of carbon and iron, though free from sulphur, and of course very difficult to refine. If, in order to avoid this reduction of iron to the metallic state, the reducing action be made feebler, it inevitably results that a considerable part of the copper as well escapes deoxidation ; and, consequently, the slags are so rich that it becomes necessary to treat them subsequently in order to recover the copper which they contain. Thus, in treating native copper, at Lake Superior, where the reducing action is purposely made feeble in order to prevent the deoxidation of the iron, the slags from the first fusion of the ore carry so much copper as to render it imperative to treat them again, which is done in a cupola. And yet, in spite of so far weakening the reducing action as to cause a notable slagging of the copper, a very considerable reduction of iron actually takes place. These are the two dangers which threaten the smelter of oxidized copper ores. If he wishes to avoid slagging his copper, he must have so strong a deoxidizing action as to reduce a great deal of his * Rivot, Prineipes Généraux du Traitement des Minerais Métalliques, i, p. 79.

Jan 1, 1879

By M. B. Standing, D. L. Katz

Equilibrium data are reported on the composition and densities of coexisting vapor and liquid phases as a function of Pressure and temperature for four hydrocarbon systems prepared from crude oil and natural gas. The data were observed over a range of pressures from 1000 to 8220 Ib. per sq. in. and at temperatures ranging from 35' to 250°F. The compositions of the hydrocarbon systems were such that the critical temperatures of the mixtures were lower than the range of the investigation. Under these conditions, it is shown that the composition of the systems has a marked effect upon both the absolute value of the equilibrium constants and the change of the constants with pressure for the several components comprising the system. From weight-balance considerations, it has been possible to construct the partial phase diagram of a mixture of a 49.9" A.P.I. crude oil and natural gas having a gas-oil ratio of 3660 cu. ft. per barrel. Descriptions of the apparatus used, the analytical procedure, the material used, and the equilibrium measurements are included. A knowledge of the physical behavior of naturally occurring hydrocarbon mixtures is fundamental to the treatment of many problems in the production, transportation and rehing of petroleum. The recent discoveries of pools having formation pressures up to 7500 lb. per sq. in. and higher, and the development of full-scale equipment to operate at pressures of 5000 lb. per sq. in. or more have greatly increased the need for knowledge of the composition, temperature, pressure and density relationships of coexisting vapor and liquid hydrocarbon phases. The following paper presents the results of investigations upon 22 mixtures of natural gas and crude oil of known com~o~itio~ that had been brought to equilibrium under controlled conditions of temperature and pressure. Data are presented upon the densities and compositions of the coexisting vapor and liquid phases for four different systems containing hydrocarbon material having boiling points from minus 2 5S°F. to well over I000 F. The data were observed Over a pressure range from Iooo Ib. per Sq. in to 8220 lb. Per sq. in. and a temperature range from 35' to 2 50°F. The accepted method of computing the physical relationship between two coexisting phases of a hydrocarbon mixture is by use of the "equilibrium constant" K as proposed by Souders, Selheimer, and Brown. definition,

Jan 1, 1944

General discussion on the above subject, presented at the Pittsburgh meeting, October, 1914. GEORGE S. Rice, Pittsburgh,. Pa.-Undoubtedly there is a serious problem through the juxtaposition of gas and oil wells and coal mines, not only at the present time, but possibly of far more serious import for the future. If one examines a map of the coal fields on which is superposed the oil and gas fields of the country, one finds that they overlap to a very great extent. I may say at the beginning that we have not, so far as I know, had any very large number, of accidents growing out of this situation causing loss of life. Such accidents, or rather incidents, that have occurred have all been rather potential possibilities for disasters due to the leakage of gas from wells into the adjacent coal mines. The condition has been most acute in the Fairmont district of West Virginia, and in the general coal fields southwest of Pittsburgh in Pennsylvania. The accidents which have actually occurred were summarized in Bulletin No. 65 (Oil and Gas Wells through Workable Coal Beds) issued by the U. S. Bureau of Mines, reporting the transactions of several meetings in Pittsburgh, February, 1913, of oil and gas well representives, State geologists, State mine inspectors, coal-mine operators, and representatives of the U. S. Bureau of Mines. This conference was partly brought about through a case in which the Pennsylvania State inspection department had brought suit to restrain a gas company from completing a well through a certain mine. The office of the Attorney General of Pennsylvania asked the opinion of the Bureau of Mines upon the matter; about the same time the Association of State Geologists, at its New Haven meeting, asked the Bureau to take up the problem. Accordingly, it was thought advisable to bring together the several, interests. For the most part the danger is, I think, greater in the future, than at the present time Many parts of the coal fields of Pennsylvania, in Greene County particularly, have been penetrated by numerous wells very close together, and with the present practice of having a large coal pillar around each well, has made or will make the mining of many areas difficult or pro-

Jan 4, 1915

By S. M. Parmley

Experience has shown that there are some factors connected with the drying of fine washed coal that are not present in drying of slack coal as normally practiced at cement kilns or pulverized coal plants. It is the purpose of this paper to show some of these variations as they have been encountered under actual operation. The Champion No. 1 cleaning plant of the Pittsburgh Coal Co. uses the wet system of cleaning coal. The plant is equipped to produce commercial sizes or mixtures, the primary sizes being plus 6 in. and 4 by 6 in., which are hand-picked. Minus 4-in. sizes are all cleaned by the wet process. To produce a commercial product as free of moisture as possible, the washed coal is first passed over sizing and dewatering screens, then each size except the — ?-in. coal is conveyed to loading booms by slow-moving draining conveyors. As the +?-in. sizes are not heat-dried, no data will be given, as it is the purpose of this paper to describe the heat drying of — ?-in. coal as practiced at the Champion No. 1 plant of the Pittsburgh Coal Company. To fully appreciate the conditions, it must be remembered that the — ?-in. product is now shipped at a lower moisture content than when received from the mine. The incoming coal in the — ?-in. size will average 5 per cent. moisture and the shipped product 3 per cent. moisture. This is a case where a wet process gives a reduction of both ash and moisture in the fine sizes. The shipped product, therefore, is more uniform in all characteristics, and uniformity of product is the most important single factor in coal preparation. The 0 by ?-in. coal is first dewatered on slow-moving continuous bucket dewatering elevators, running at the rate of 40 ft. per minute, with 48-in. perforated buckets with ¼ by 1½-in. slots, spaced ? by 2?-in. centers staggered. The moisture in the coal discharged from the elevators runs 20 to 28 per cent., depending on the fineness of the product. The discharge from the dewatering elevator is further drained on a drag-type conveyor equipped with ½-mm. wedge wire screen. The conveyor discharges coal with an 18 to 25 per cent. moisture to three centrifugal dryers of the Carpenter type. The Carpenter dryers

Jan 1, 1931

By Augustus J. Bowie

THE discovery of the auriferous cement gravel deposits in and near Deadwood Gulch, Lawrence County, Dakota Territory, in 1876, created a mining excitement, and rush to the Black Hills. Numerous ten and twenty-stamp mills were built on Deadwood Gulch ; Central City and the town of Deadwood sprang into existence, and became the centres of the mining industry of the Hills. Gold quartz deposits were subsequently discovered and located on a so-called mineral belt, extending from Whitewood Creek on the south, to Deadwood Gulch on the north. A northerly group of these quartz locations was purchased in December, 1877, by parties in San Francisco,, who formed a company, incorporated under the name of the Father de Smet Consolidated Gold Mining Company. This company immediately commenced the work of exploration. The deposits were proved to be extensive, and easily mined, but it was found that the ore, on an average, would not. yield more than $10.00 per ton* of 2000 pounds. At this time the cost of supplies and materials in the Hills was high. Miners' wages were $3.50 per diem, and custom mills charged $6:00. per ton. The successful working of mines on "the belt" necessitated cheap milling. The ores being of so low grade,† this could be accomplished only with large and economically running mills. To insure the greatest possible economy, the Father,& Smet mill * Up to December 31st, 1879; the de Smet mine had produced bullion of the value of $718,211.68 from 76,155 tons of ore, being an average value of $9.41 per ton. During the year ending December 31st, 1879, the mine produced 46,344 tons, which yielded $425,360.42, or $9.18 per ton. The total gross cost of working for the corresponding period, including deadwork, exchange, legal expenses, fete., wits $219,914.82. The yield of the mine for the year 1880 (Engineering and Mining Journal, February 5th, 1881), was $600,011, with total expenses of mining and milling, of $313,108. † The first 4083 tons extracted from the de Smet mine, were selected, yielding $62,783.97. The next 25,728 tons produced $230,067.24. The total 29,811 tons were weighed, and worked at custom mills. The yield of the first 409 tons from tine Golden Terra Mine was $11.44 per-ton.

Jan 1, 1882

By L. A. Willey

IN 1953, a method for filtering a liquid phase from solid phases while in equilibrium at elevated temperatures was devised at the Alcoa Aluminum Research Laboratories. Since then, it has been applied to the investigation of liquid-solid equilibrium in metallic systems. In application, the method simplifies the centrifuge filt.ration procedure as developed by Scheil and described by Gebhardt Fig. 1 shows a sketch of the filtering apparatus located within a thermal analysis furnace. It consists of a stainless steel filter crucible A, into the bottom of which a porous carbon filter disk B, 1 3/4 in. diam by 1/4 in. thick, is sealed to the shoulder and rim with carbonaceous cement. The base of the filter crucible, machined to an angle, fits into a tapered seat at the mouth of a stainless steel vacuum chamber C. A connecting tube from the vacuum chamber to a vacuum line also serves as a means for supporting the apparatus from the base of the furnace. An alundum crucible D of 25 ml capacity is placed with- in the vacuum chamber below the filter for collecting the filtrate. Two thermocouples E, in stainless steel protection tubes, which extend from 1/16 to in. above the center of the filter, are mounted on the rim of the filter crucible. One thermocouple is used in differential connection with the furnace control thermocouple to regulate rates of heating and cooling. The other serves as a means for recording the temperature of the alloy prior to filtering. A suitable mold coating is used on exposed surfaces of stainless steel parts to guard against attack upon these parts as well as to avoid contamination of the alloy samples. A mold wash prepared from precipitated CaCO, is suitable for aluminum alloys. The porous carbon for the filter disks and the carbonaceous cement, grade 200 (graphite base), were obtained from the National Carbon Co. Porous car-bon, grade Nos. 10 to 60, has been employed. Grade No. 40, however, appeared to give the optimum advantages in operation. In operation, an alloy sample is remelted and heated to about 50°C above its liquidus temperature. At the same time, the filter apparatus is preheated to about the same temperature. The alloy then is cast into the filter crucible.

Jan 1, 1957

By Walter O. Snelling

In the course of some experiments more than five years ago, made for a totally different purpose than the investigation of the oil used, I placed a small quantity of a transparent yellow lubricating oil in a bomb-like vessel and heated it to a relatively high temperature. At the end of the experiment I removed the oil from the vessel and was amazed to find that instead of bearing any resemblance to the oil which I had put in, it now had the appearance of ordinary crude oil. The green color by reflected light and the rich red-brown by transmitted light were so unmistakable as to at once lead to further investigation. I subjected the material to fractional distillation, and the surprise which I experienced at the appearance of the oil, changed to amazement when I found that it yielded, on distillation, 15 per cent. of gasoline and 30 per cent. of burning oil, and that its constitution resembled crude oil quite as much as did its appearance. Furthermore, the gasoline and kerosene distillates which it yielded were of a clear water-white color, entirely without treatment with acid or alkali, and were entirely free from the odor familiar in "cracked" petroleum distillates. The result of this experiment was quite too remarkable to be credited without further confirmation, and I at once filled the vessel with some of the same oil that I had used before, and again heated to about the same temperature that I had previously used, and for the same period of time. Upon opening the vessel and removing the contents I found, not the material resembling crude oil that I had obtained before, but apparently only the same oil that I had put in, somewhat darkened in color, but nevertheless far different in appearance from the material obtained in the previous experiment. Evidently some condition existed in the first experiment that had not existed in the second test, and here began a series of tests in which I sought by the change of one variable after another to arrive at the identical conditions which must have existed in the first experiment. Only the fact that the bottle of heavy oil used in the first test was still in its place,

Jan 1, 1915

By H. R. Collins

The purpose of pulverizing coal before burning it is to make available every heat unit it contains. Machinery has been developed which will pulverize coal in one operation, delivering it to bins in front of the furnaces at an expenditure of about 17 hp.-hr. per ton, in a medium-sized plant. The cost of the operation depends upon the amount of moisture that must be expelled before pulverizing, the cost of labor, and the cost of coal delivered at the plant. At a small plant, requiring a pulverizer with a capacity of only 1/2 ton per hour, the cost per ton pulverized will naturally be greater than at a plant requiring the largest pulverizer, with a capacity of 7 tons per hour. :The first step is to reduce large lumps to a size suitable for drying uniformly, before passing to the pulverizing mills; this is done in rolls, at a single pass. The second step is the elimination of moisture, in order to facilitate pulverizing to great fineness, while also increasing the heating effect and the temperature attainable when the coal is burned. There are other mechanical advantages in the handling of dried coal. Driers are now manufactured which are able to eliminate moisture without distilling any of the volatile combustible matter in the coal; they are fired by hand or with pulverized fuel. The heat first surrounds the shell of the drier, being confined within a chamber where complete combustion takes place; the heated gases are then led through a duct to the discharge end of the drier and enter the inside of the shell at a temperature not exceeding 300" F. This temperature is maintained by the operator and is indicated by a pyrometer. Volatile combustible matter is not likely to be distilled until the temperature rises above 400" F. On discharging from the drier, the coal is usually passed over a magnetic separator in order to prevent pieces of iron from going to the pulverizer. Two types are used: a magnetic pulley which automatically discharges its collection of iron, and a lifting type, from which the iron is removed by hand when convenient. In the operation of pulverizing, the coal should preferably be reduced until 95 per cent. will pass through a 100-mesh and 70 per cent. through a 300-mesh sieve. Such a product is obviously an almost impalpable powder.

Jan 1, 1920

By C. O. Brawner

Introduction The procedures used to design slopes in rock have only been developed over the past 10 years. Therefore, continued review and assessment of field experience by the publication of case studies is necessary to determine the accuracy of the theory and the application of the design techniques being used. Where failures have occurred, mine management should insist that the slides be 'back analyzed' to determine the shear strength parameters at failure. These values should be used for any pit design as they reflect site conditions more accurately than any other procedure. The previous papers have dealt with the basic concepts and factors that influence stability. To illustrate the application of these concepts in the study of practical stability problems, six ease studies have been selected for review. The examples include failure of tailings dams due to an earthquake, failure and redesign of a slope in overburden, review of failures of rock slopes, calculation of the amount of seepage into a pit and influence of the groundwater on stability, and the design of slopes for a proposed 2,500 ft. deep open pit mine. All but the first example are drawn from the authors personal experience. EXAMPLE 1 Failure of Tailings Dams Due to an Earthquake On March 28. 1965 a serious earthquake occurred in Chile with the epicenter located near the town of La Liqua, about 80 miles north of Santiago. The earthquake had a rating of 7 to 7.25 on the Richter scale. A record of the acceleration was taken at Santiago where a maximum horizontal acceleration of 0.18 g. was recorded. Many small mines are located in this region. Each of the mines provided impoundment storage for tailings with one to three dykes. As a result of the earthquake, most of the dams failed. The most serious failure involved two dams at El Cobre where more than 2,700,000 cu. yd. of tailings flowed into the valley, travelled over 7 miles in a few minutes, destroyed part of the town of El Cobre and killed more than 200 people. The Chilean government commissioned an investigation into the failures. A summary of the findings was published by Dobry and Alvare7 in 1967 (1). The location of the earthquake and the tailings dams which were investigated is shown

Jan 1, 1971