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By Charles P. Berkey, John B. Hastings

The reconnaissance of the Goldfield mining-district, describecl in this paper, was made in May and June, 1905, and, though this time was too short for a complete report, the work accomplished may serve as a basis for more thorough future research. Dr. Berkey has examined the rocks collected by me, and I am using his classifications. As a result of further field-work, and Dr. Berkey's examination of the rocks, this paper is an elaboration and correction of my views expressed in the Gold-$elm Sun, May 12, 1905. The sketch-map, Fig. 1, illustrates the geology of the Goldfield mining-district. Goldfield is an eruptive complex, consisting of alaskite (hinary granite), hornblende-andesite, hornblende-dacite, rhyolite, pyroxene-andesite, pyroxene-dacite (sometimes containing a small quantity of olivine), quartz-felsite, olivine-pyroxene-ande-site, and basalt. Considering this list to be arranged in the order of eruption, the age-sequence of the rocks conforms to Richthofen's law, formulated in 1868. From his observations in Europe and America, propylite, andesite, trachyte, rhyolite and basalt, occurring together, succeed one another. In a general way, the medium and the more acidic rocks precede the most basic—a result supposed by some to hare arisen from their position beneath the. surface, and due to a rude stratification by gravity in the original cooling magma during the older history of the earth, or to the same differentiation occurring during a quiescent (molten ?) period preceding eruption, being aided by the ease with which acidic rocks, mixed with water vapors, become fusible. In effect, the more basic and less re-

Jan 1, 1907

By T. A. Rickard

INTRODUCTORY. THE presentation to the Institute, eight years ago, of the paper of Pošepny on " The Genesis of Ore-Deposits " has borne fruit in much fresh: investigation, as is evidenced, for example, by the group of very valuable papers, by distinguished members" of the United States Geological Survey, read at the Washington meeting-discussions of general principles particularly suggestive to those who are engaged in mining. Pošepny, in the discussion of his famous treatise, said that the present writer seemed to look at every new conception in ore-deposition" from the sole standpoint of its immediate usefulness in mining."* Protesting mildly against " sole " and "immediate," I accept the impeachment. It calls for no defence. THE DEVELOPMENT OF RECENT THEORIES. Given the idea of an underground water-circulation as the chief factor in the deposition of ore, the next step in the inquiry as to the genesis of such deposits is, the endeavor to determine which particular part of the general water-circulation is responsible for the results. Around this question have centered the controversies of a generation, and to these controversies we owe the gradual clarification of our ideas upon the processes of ore-formation. It is unnecessary to sketch here their progress from Werner to Le Conte, who combated in 1883 the extreme views of the lateral-seeretionists, and in 1893 opposed the narrow interpretation of the ascensionist-theory. The generally accepted opinions of to-day are a well-deserved tribute to his philosophic discrimination. Thanks to Prof. Van Hise and Mr. Slichter, whose work he utilizes, we have now arrived at a comprehensive conception

Jan 1, 1902

“The mining industry can do more to alleviate world poverty, hunger and human misery, more to close the widening gap between advanced and developing nations and more to achieve international peace and understanding than any other single force in the world," Charles W. Court, Minister for Industrial Development, Western Australia, told the American Mining Congress audience at the opening session of the 1969 Mining Convention, October 19-22, San Francisco. Australia, he pointed out, is a shining example. In 1971, 60% of U.S. mining investment overseas will go to Australia and other parts of Oceania, an increase of 42% over a year ago. Australia has capitalized on world needs, its own rich resources and good investment climate. Developing nations can and should do the same, but they mix emotion with nationalism, often frightening away foreign investment which could breathe life into dormant and backward areas, said Court.

Jan 12, 1969

By A. U. Seybolt

The solubility of oxygen in a iron has been determined in the range between 700° and 900°C. The solubility is a function of temperature and varies from about 0.008 pct oxygen at 700°C to atureandabout 0.03 pct at 900°C. The heat of solution is approximately +15,500 cal per mol. AS pointed out in a recent paper by Kitchener et al.,1 there has been a lack of agreement among many investigators even as to the order of magnitude of the solid solubility of oxygen in the various forms of iron. This lack of agreement is attributable in large part to the difficulties in the determination of a small oxygen solubility; but because the problem has remained so long unsettled, it also indicates a lack of interest which is rather surprising when the demonstrated importance of small amounts of soluble nonmetallic impurities in iron is considered. The work of Kitchener et al. apparently leaves the solubility of oxygen in iron in a satisfactory state, but no attempt was made to investigate the solubility in a iron. The solubility of oxygen in a iron is actually of greater interest, since it is in this form that iron and mild steels are employed ordinarily. That the effect of oxygen in iron is of more than theoretical interest has been well established by Fast,' and more recently by Rees and Hopkins," who demonstrated that oxygen in the range between 0.0008 and 0.27 wt pct has a pronounced effect upon the mechanical properties. Previous Work and Methods Used To report in detail the literature relating to the solubility of oxygen in a iron would require an inordinate amount of space. For those interested in reviewing this work, a bibliography4-13 of the more significant papers is appended. In general, two methods of studying this problem have been used. One is the gas-metal equilibrium method where the H2O-H2-Fe or the CO2-CO-Fe equilibria have been used. The other is the more direct approach of the oxidation of thin strips of pure iron by packing in mill scale or by air or gaseous oxygen at some desired temperature. In this method oxygen is allowed to oxidize the surface and then to diffuse inward until saturation is obtained. In the gas-metal equilibrium method the oxygen dissolved in solid iron at a given temperature is proportional to the ratio of the water vapor-hydrogen pressures or the CO2-CO pressures over the sample for small ratio values. If the ratio becomes higher than a critical value, then an oxide phase makes its appearance (the solution becomes supersaturated). In principle, it is possible to use a series of H2O/H2 or CO2/CO ratios and to find by analysis the corresponding amounts of oxygen in solid solution at constant temperature. At the point where a very small increase in the gas ratio (increase in oxidizing powder) produces a large increase in oxygen content, the solid solubility limit is reached. Alternately, if the critical ratio is known, it is possible to use the procedure of Kitchener et al.1 and to use a ratio which is near but below the critical one. The solubility corresponding to this lower ratio will not be the saturation solubility at the temperature employed, but the saturation solubility can be calculated by multiplying the measured solubility by the critical ratio over the ratio used. However, in the case where oxygen gas is the oxidizing medium, the saturation solubility is not a function of pressure, providing the pressure exceeds the dissociation pressure of FeO in equilibrium with iron. This is 1.2x10-16 mm at 800 °C, according to Dushman." As pointed out by Darken17 in discussing the FeO phase diagram, most of the possible errors tend to yield high values of oxygen solubility. For example, one circumstance which evidently caused the reporting of many high values was the use of finely divided or powdered iron in the gas equilibrium method. Because of the large surface area of such a sample, and the likelihood of some surface contamination if only by exposure to air, the results tended to be high. The direct oxidation method which was used in this work has the advantage in that it is simple and direct, but it suffers from one disadvantage: equilibrium can only be approached from the low oxygen side. The important factors to be kept under control are the following: 1—use of high purity iron to avoid internal oxidation (oxidation of readily

Jan 1, 1955

REGULATIONS (proposed) for the location, drill-ing, casing, protection, operation, plugging and filling, and abandonment of natural gas and petroleum wells; having for their objectives. the protec-tion of life and property by prevention of intrusions of oil and gas into workable coal beds, and the conserva-tion of oil and gas resources in territory not underlain with workable coal beds. ARTICLE I Definitions Section 1.-For the purpose of these regulations (proposed), definitions are as follows: Well.-A bore-hole drilled for the purpose of developing natural gas or petroleum, or a bore-hole producing natural gas or petroleum. Well Operator.-Any person, persons, firm, partnership, corporation, company or association that proposes to, or does drill, operate, or abandon a well as herein defined. Coal Operator.-Any person, persons, firm, partnership, corporation, company or association that proposes to, or does operate, a coal mine in territory known or reputed to be underlain with oil or gas-bearing strata. State Mining Department.-The duly constituted authorities of a state having jurisdiction over coal-mining operations. Plat.-A map, drawing, or print made in accordance with the pro-visions of these regulations (proposed). Casing.-The pipe greater than 3 in. in diameter commonly used in wells drilled for natural gas and petroleum. Oil and Gas.-Synonyms, respectively, for petroleum and natural gas. Cement.-Hydraulic cement properly nixed with water only. Workable Coal Bed.-A coal bed in which, in the united judgment of the coal operator, the well operator and the State Mining Department, protection for life or property will be required when wells are drilled through it.

Jan 7, 1927

By P. L. Allsman

Butte mining district contains extensive manganese vein deposits forming a peripheral zone. Oxidation in the veins studied usually extends to a depth of about 75 ft. Secondary minerals formed by oxidation were found to be ramsdellite—always accompanied by intermixed pyrolusite—and cryptomelane. Enrichment of the gossan is accomplished by reduction of weight upon oxidation; theoretical enrichment is 32.2 pct. Additional enrichment is caused by leaching of soluble minerals, particularly calcium and magnesium carbonates. BUTTE mining district contains extensive manganese vein deposits in the outer zone, surrounding the copper and zinc deposits and corresponding to the well known silver zone. This article describes the mineralogy of the manganese veins, the oxidation and enrichment processes, and the use of this information in prospecting. Information was derived from a study of the Emma, Star West, Tzarena, and Norwich mines, selected as representative of the district. Vein exposures at these mines were mapped, studied, and sampled on the outcrops and throughout the oxidized zone. Specimens were cut and polished for minera-graphic examination, identification, and textural studies. Knowledge of the manganese oxide minerals is scanty, previous information having been rendered obsolete by publication of the first correctly identified list of manganese oxide minerals by Fleischer and Richmond in 1943. Positive identification of the manganese oxides is possible only by X-ray analysis. Identifications for this study were made by the author with a Phillip's Diffractometer at the Montana School of Mines and confirmed by Lester Zeihen of The Anaconda Co., using a Norelco X-ray camera. It was necessiary to re-evaluate some X-ray data, as published patterns of several manganese oxides proved to be of mixtures, mostly showing pyrolusite as a contaminant. Perhaps the most useful information on oxidation and enrichment of manganese is presented in recent books by Goldschmidt1 and Rankama and Sahama.2 While their hypotheses are not conclusively proved, all laboratory and field evidence has served to substantiate them. This information was very useful in this study. Mineralogy: The primary minerals of the manganese veins are chiefly rhodochrosite and quartz. Rhodonite is abundant in the northern part of the district and in places has been found to comprise over a third of the vein matter. A variable but generally small amount of sulfides may be present, principally pyrite and silver minerals. Sphalerite is progressively more abundant near the zinc zone. Rhodochrosite is believed to form complete iso-morphous series with siderite, ankerite, and calcite. Some variation into these compositions is common, and the intermediate forms are termed manganosid-erite, manganankerite, and rnanganocalcite. Much of the rhodochrosite is remarkably pure. Other manganese minerals in the district include huebner-ite, alabandite, and helvite. Ramsdellite (MnO2, orthorhnmbic) is the principal manganese oxide mineral, comprising perhaps two-thirds of the total oxides. It is dull to iron black, and generally massive or platy in structure. A prominent platy cleavage is the only distinguishing megascopic characteristic. Pyrolusite (MnO2, tetragonal) is next most abundant to ramsdellite, with which it is usually intimately mixed. The luster is often brighter or more metallic than in ramsdellite, and needle-like crystals are diagnostic. Pyrolusite is common in small cavities formed by oxidation of pyrite grains. It is relatively abundant in zones of high limonite content. Cryptomelane (KMnO16 tetragonal ?) is rare in the outcrop, but becomes more abundant with depth. At depths of several hundred feet it is the principal oxide. Although its appearance varies, a blue-black flinty luster and blocky to conchoidal fracture are most common. A potassium flame test will identify this mineral. Hardness of all three oxides varies from 2 to 6. The three are quite commonly intermixed, and their textures can vary greatly. The commonest textures are massive or colloform, representative of colloidal deposition, or vuggy and boxwork textures, formed by partial leaching and oxidation in place. A box-work of either ramsdellite or chalcedony is formed after rhodochrosite rhombs and is indicative of ore shoots in this district. Some replacement of both quartz and the granitic wallrock by ramsdellite has been noted, but most of the oxide was deposited as a fissure filling by fine particles. No trace of manganite, hausmannite, braunite, or manganosite was found. No minerals of the psilome-lane group were detected besides cryptomelane. Amorphous MnO, was found at several spots. A specimen of oxide coated with yellow barite crystals was amorphous and not psilomelane (BaMn9O18. 2H2O). Voids formed by the leaching of sphalerite were coated with cryptomelane, not hetaerolite (ZnMn2O4) as might be expected. No manganese sulfate minerals were found in the gossans; however manganese alum (apjohnite ?) has been re-

Jan 1, 1957

E. A. HOLBROOK,*Urbana, Ill.-To those who have followed the development of powdered coal two questions often occur. First, as to the moisture in the coal. In Illinois we recognize that the bituminous coals contain about 12 to 15 per cent. of what we call "contained moisture," that is, the moisture is present in the coal although this may appear absolutely dry and dusty. In addition, the surface moisture may be present in any amount. I would like to ask what is the relative effect of these two forms of moisture upon the work of pulverizing. Does Mr. Collins refer to the contained moisture or to the surface moisture in estimating the degree to which the coal must be dried? H. R. COLLINS.-In the lignite coals, of which this country possesses a great deal and is beginning to develop them to considerable extent, the "contained" or "combined" moisture does not .trouble us; we have no difficulty in reducing lignites to a high degree of fineness. But when dealing with bituminous, sub-bituminous, or semi-bituminous, we, prefer to reduce the combined moisture as well as the hydroscopic moisture as far as possible. We have recently put into operation, at a plant, furnaces and boilers consuming the lignite from northern New Mexico, which contains between 4 and 5 per cent. moisture as we pulverize and burn it. The evaporating efficiencies under the boilers have been so remarkable that we wish to check the results half a dozen times before quoting them. We have also just started two boilers at the Garfield smelter, and have obtained the same high efficiencies.

Jan 11, 1918

By L. R. Jackson, W. T. Lankford, K. F. Smith

COMMERCIAL steel sheet is prepared by a combination of hot and cold rolling and annealing. This treatment usually results in more or less pronounced anisotropy. The [ ] anisotropy may manifest itself both as preferred orientation and in the manner in which impurities, segregations, and the like, are aligned in the sheet. The type of preferred orientation and the organization of impurities or segregations may affect the elastic moduli, the yield strength, the tensile strength, and almost always the amount of ductility in different directions. In any case, the most important directions concerned in the anisotropy are along the rolling direction, along the width direction, and along the thickness direction. Considerable data exist on the anisotropy of sheet steel as demonstrated by conventional tensile tests; however, few attempts have been made to measure the constants of plastic anisotropy and use them to describe the flow of anisotropic sheet under combined stresses. [ ] In this paper, evidence is presented indicating that plastic flow in anisotropic sheet can be described by the shear-strain energy flow theory provided that the anisotropy is properly taken into account. MATERIALS USED IN THE INVESTIGATION Table I lists the sheet materials used in this investigation and describes the condition in which materials were tested. DESCRIPTION OF TESTS AND TEST METHODS Two types of tests were run-tensile tests and hydraulic-bulge tests. Characteristic parameters of anisotropy were determined from the tension tests by methods which will be described later. In all cases, the tensile test pieces were cut from the same quarter line and adjacent to the bulge test pieces in the sheet in order to minimize

Jan 1, 1948

By J. J. Tietjen, D. Richman

Single-crystal Gap lms been epitaxially grow from the vapor phase at a rate oJ 3 p per nzin without encountering a7Zy low-ang-le grain boundaries or debwading- the electrical properties of the material. This growth rate exceeds any value previol~sly reported for the vapor phase growth of Gap. In pure material, mObilities ns high as 175 sq cm per U-sec at room tenzperature and 1450 sq cm per v-sec at 77°K have been obtained. These values are anLong the highest that have been attai)led for this material. For the first time, Gap possesses a number of important properties which make it well-suited for use in electro-optic modulators. First, the transverse electro-optic effect is operable in this material, which makes it possible to increase the path length of the modulated iron doping of Gap has been achieved; this results i?z resistivities of approximately 10" ohm-cm. The problelrls of residual strain and isolated shorting paths in these crystals have been partially solved. Electro-optic modulation of visible radiation has been demonstrated with this material. It is anticipated that further improvement with regard to the probleins of strain and shorting paths will result in a practical Gap electro-optic modulator. radiation without increasing the applied voltage. In addition, this permits the use of thin crystals so that relatively small voltages are needed to provide the requisite high electric fields. Second, GaP is a cubic crystal and therefore does not introduce critical optical-alignment problems associated with birefrin-gent crystals, such as ammonium dihydrogen phosphate (ADP), and potassium dihydrogen phosphate

Jan 1, 1968

By Frank R. Milliken

This paper is a running commentary on metallurgical problems and developments, stressing ilmenite flotation, since the start of operations five years ago, at the mill of National Lead Company, Titanium Division, MacIntyre Development, Tahawus, New York. In early 1941, when world conditions threatened to cut off the supply of ilmenite (obtained largely from India) to this country, the National Lead Company started to develop and bring into production their MacIntyre Development. This operation supplied the bulk of the ilmenite used during the war period for the manufacture of the much needed titanium pigments. MacIntyre Development is at Tahawus, New York, on the headwaters of the Hud- son River in the center of the scenic Adirondack Mountains. A general description of the operation was given in the Adirondack Issue of Mining and Metallurgy for November 1943. Operating tonnages and production have increased since 1943, however. Nearly 10,000 tons of.ore and waste is broken and loaded daily in the open-pit mine. About half of this tonnage is ore, from which is produced nearly 800 tons of ilmenite concentrate and 1600 tons of magnetite concentrate daily. Ore—types From an ore-dressing standpoint, there are five rather distinct ore types and two waste-rock types in the mine. The ore types are shown in Table I. The anorthosite waste is a coarse-grained white rock, largely labradorite feldspar. The gabbro waste is generally finer grained, and contains, in addition to feldspar, 35 to 75 pct iron silicates such as hornblende, in garnet and biotite. A minor mineral mineralogically, but important metallurgically, is apatite. A few calcite

Jan 1, 1949

By James R. Jones

The concern for air pollution goes back centuries as will be seen from this quotation : "Strife and coal, it seems, have a hand-in-hand historical relationship. It was thought by some . . . in the Middle Ages that burning coal filled the air with dangerous poisons. So great was the concern that in 1306 King Edward I of England passed the first and unquestionably the harshest air pollution legislation edict that history will record. His proclamation declared the use of coal an act punishable by death." As related to coal mining, the air pollution problem is primarily that of its customer when using the fuel. Thus the major impact relates to markets for coal rather than the actual mining operation itself. In the vicinity of the coal mine the problem is principally related to fugitive dust from roads, transfer facilities, loading facilities, crushers, etc., and particulate matter (dust or fly ash) from thermal dryers and air cleaning tables. FUGITIVE DUST Most state air pollution regulatory agencies now have rules and regulations requiring control of fugitive dust. Fugitive dust has been defined by the courts as particulate matter other than that emanating from a specific point such as a stack or chimney. A typical air pollution control agency regulation reads as follows : “Fugitive Dust " "No person shall cause, suffer, allow, or permit any material to be handled, transported, or stored; or a building, its appurtenances, or a road to be used, constructed, altered, repaired or demolished without taking reasonable precautions to prevent particulate matter from be- coming airborne. Such reasonable precautions shall include, where applicable, but not be limited to the following:

Jan 1, 1981

By Charles Albert Ashburner

Natural gas has been known to exist for many years in the St. Lawrence Valley, between Quebec and Montreal, and more partirularly in the vicinity of Louisville and Three Rivers, 74 and 94 miles respectively northeast of Montreal, and 98 and 78 miles respectively southwest of Quebec; the distance from Montreal to Quebec along the St. Lawreuce River being about 175 miles. It was not until 1880 that any practical explorations were begun with the hope of finding gas in sufficient quantities for commercial uses. In this year Messrs. Piret and Genest, of Three Rivers, sank a well near St. Maurice to a depth of 50 feet, where solid rock was encountered. A similar well was drilled through the glacial and allavial drift, in the same district, in 1883, by the Messrs. Renaud Freres and Dubois, to a depth of 70 feet before solid rock was encountered. In this latter well a strong flow of gas was obtained. The gas was an outflow from a very limited reservoir in the porous glacial gravel, which had been filled from the gas resulting from the decomposition of vegetable remains, which had been buried in the gravel at the time of its deposition. Subsequently, other wells were sunk in the same way, with the hope of getting gas in commercial quantities from similar reservoirs. Commercial Gas.—By gas in commercial quantities I mean gas in such quantity that, if utilized with proper care and economy, it would generate steam at a cost below the cost at which the same duty could be obtained from the use of coal or wood at current prices, and that

Jan 1, 1890

By E. T. Dumble

In continuation of the geological work begun in Sonora, Mexico, a partial account of which has already been given in the Transactions of the Institute,* a similar reconnaissance was made of Cochise county, Arizona, and a part of the Whetstone mountains. The investigation resulted in the identification of beds of similar age and character to those of the Sonora region, and in the discovery of interesting deposits, which, so far as I call ascertain from the literature at my command, have not been described heretofore. Route.—Starting from Nogales, we followed the railroad to Crittenden, and then drove to the southeastern slope of the Whetstones. After a brief examination of some reported coalbeds we continued our route, following the wagon-road between the Whetstones and the Mustang mountains to Huachuca, and eastward to Tombstone. Crossing the Dragoon mountains at South Pass, we traveled south and west by way of Turquoise and Antelope Spring into the road from Tombstone to Bisbee. Our route over the Mule mountains lay through Mule Pass and Bisbee, where we stopped a day or two. Thence, crossing Sulphur Spring valley, we drove around the southern end of the Swisshelms, and N. through the valley between these mountains and the Chiricahuas, to White river. From that point our way led through Rucker canon into the San Simon valley, then northward along the eastern face of the Chiricahuas, and by way of Fort Bowie to Willcox, Arizona, from which place we returned to Nogales. It was greatly regretted that the extremely wet weather prevented us from including in our examination the Huachuca

Jan 1, 1902

By Marius R. Campbell

Does mine-sampling show the commercial value of a coal, and if so, how should it be done ? This question is often asked, but seldom answered. During the past summer, while engaged in securing coal for the Government coal-testing plant at St. Louis, I had an excellent opportunity to obtain information on t,his subject, and the results seem to furniih an answer to the question propounded above. Sampling for the U. 8. Geological Survey Coal- Testing Plant. In organizing the work of the testing-plant, it was decided that coal, in car-load lots only, would be accepted for testing; also that this coal should be loaded under the immediate supervision of a representative of the plant, so as to be certain that the car-load sample would be representative. As an additional check on the work, two mine-samples were to be collected from each mine visited, and these samples, as well as the sample from the car when it was received at the testing-plant, were to be carefully analyzed at the chemical laboratory established in connection with the plant and operated under the direction of Prof. N W. Lord of the Ohio State University, Columbus, Ohio. Mine-Samp1ing.—Mine-samples were collected with great care by me and my assistants, Messrs. J. Shober Burrows, John W. Groves and Frank W. De Wolf. The dominant idea in the regulations adopted for mine-sampling mas, that it should be done in such a manner that the sample would have the same composition as the commercial output of the mine.

Jan 1, 1906

By H. E. N. Stone, B. L. Daniell

This paper examines the cracking behavior on chemical reduction of three types of ore/oxide briquette mixtures. The complex sintering/hardening atmosphere was replaced by 100% oxygen and the blast furnace atmosphere by a 5/95 hydrogedsteam mixture which was used isothermally at 700°C for a constant, arbitrary time. Cracking has been assessed by measurement of reduction expansion or increase in specimen diameter as a result of chemical reduction and a subjective index based on appearance and friability. Oxidized briquettes of iron ore concentrate crack on reduction'-3 in a manner which parallels the degradation of sinter in the Linder test. In the present work, the cracking behavior on chemical reduction of three types of ore/oxide briquette mixture has been studied. Firstly, LD converter fume with additions of silica; secondly, Oxfordshire ore with ferric oxide; thirdly, ferric oxide with separate additions of silica, alumina and lime. Motivation for the first-mentioned experiments lay in the improvement of the fume as furnace feed; for the second, in assessing the tolerance of a finely divided ferric oxide as a base for low melting point additions. The third series provided additional information. In this work, the complex sintering/hardening atmosphere is replaced by 100% oxygen and the blast furnace atmosphere is replaced by a 5/95 hydrogen/ steam mixture used isothermally at 700°C for a constant arbitrary time. The particular reduction conditions were known from previous experience3 to be capable of disclosing any tendency to cracking. Cracking has been assessed by measurement of reduction expansion (i.e., increases in specimen diameter as a result of chemical reduction) and a subjective index based on appearance and friability. Generally

Jan 1, 1970

By Terry Ramsey

INTRODUCTION The Cyprus Pima Mine is located 20 miles southwest of Tucson, Arizona and about fifty miles north of the Mexican border. The Cyprus Pima orebody was discovered in 1950. Feasibility studies were begun in 1952 employing underground development. Economic studies showed open pit operations to be feasible and stripping of overburden was begun in late 1955. The first ore was reached in October of 1956. A 3,000 tpd (tons per day) concentrator was completed and began operation January 1, 1957. From these beginnings, Cyprus Pima Mining Company has expanded into a plant processing approximately 54,000 to 56,000 tpd. Four expansions were required to bring the plant up to its present capacity. Each expansion incorporated what had been learned in previous operation of the plant. The first expansion was completed in August of 1963 doubling design capacity to 6,000 tpd. In reality, because of softer than average ore, capacity was closer to 8,000 tpd. Expansion II was completed in July 1966 bringing design capacity to 18,000 tpd. Expansion III followed immediately. Completed in the summer of 1967, this expansion increased the design capacity to 30,000 tpd. The actual dry tonnage of this portion of the operation in 1974 averaged 38,400 tpd, again, primarily as the result of treating softer than average ore. The latest expansion (Expansion IV), completed in December 1971 and utilizing a semi-autoge- nous grinding circuit, is located in a separate building (Mill II) approximately 200 yards southeast of the original mill (Mill I). Expansion IV was designed for 14,000 tpd, but after circuit modifications, averaged 16,500 tpd in 1974.

Jan 1, 1976

By Carroll F. Hardy

THE position of the coal industry has been affected by a wide variety of developments in the production and use of energy. The tempo of development and change has been increasing and the end is not in sight. Legislation is currently being proposed for commercial use of atomic power, and the employment of atomic energy in significant quantity will probably occur about the same time as the decline in production of petroleum and natural gas. But these developments are in the future and have little immediate effect on utilization and marketing of coal. While no one should try to suppress or retard the development of a new and economical source of energy, both the coal and private utility industry should be allowed to question how the nuclear power is to be used, who is to use it, and who is going to pay for it. The taxpayers have a monopoly on fissionable material and the knowledge to employ it. Any commercial use must stem from this source. It is not hard to visualize either taxpayer- subsidized private utility atomic power plants on one hand and super TVA's on the other. In view of the gains of gas and oil in the home heating field, it is interesting to compare the 1940 and 1950 census reports on the kind of fuel used for heating in occupied dwelling units. Table I shows that whereas coal provided 77 pct of the fuel for central heating (furnaces and boilers) in 1940, it was down to 45.4 pct in 1950. However, only about 1 ½ million units were lost in this 10-year period.

Jan 3, 1954

By Frederick Laist

IT IS obviously impossible to design a copper smelting plant which could be considered, ideal under all conditions. For example, a plant properly designed to smelt the concentrates resulting from the treatment of porphyry ores by flotation would not be the kind of plant that one would design for the treatment of a coarse pyritous copper ore. The smelting of flotation or other fine concentrates is generally accomplished in a reverberatory plant, although occasionally the concentrates are sintered and then smelted in blast furnaces. On the other hand, coarse self-fluxing ores, whether pyritic or semi-pyritic, are generally smelted in a blast-furnace plant. Even this statement is only- approximately true, since the choice will be influenced by many factors; for example, the kind of fuel available (coal, oil or coke), the value of power (electric or steam), the uses to which waste steam may be put (heating, drying, etc.), the cost of refractories (silica and fire brick), the permanence and continuity of the ore supply and the relative first costs of the two types of plant (the reverberatory plant is generally more expensive to construct and to shut down), the contour of the site on which the plant is to be built (rugged, rolling or flat), the intelligence and character of the labor avail-able, and many other factors. From these remarks, it is evident that no copper smelter can be ideal for all conditions of ore and locality, and inasmuch as most of the copper now being pro-duced comes from fine or flotation concentrates and these are generally smelted in reverberatory furnaces, I shall confine my remarks to this type of smelt-ing plant.

Jan 5, 1923

By W. R. Toeplitz

Probably a more descriptive title would be "Much Ado About Nothing." By "nothing," of course, I refer to the porosity which is the main feature of this type of bearing. Porosity has a decided effect on the manufacturing techniques, the structure and physical properties, the oil content, and on the installation and service of oil-retaining porous bronze bearings. A simple curve can be drawn by plotting specific gravity along the abscissa and percentage of porosity by volume on the ordinate. A bronze composition, analyzing 89 Per cent copper, 9.75 Per cent tin, and 1.25 per cent graphite, has an absolute solid specific gravity of 8.5. At this specific gravity, of course, occurs the point of zero porosity. Conversely, at loo per cent porosity, the specific gravity is zero. A similar curve can be drawn for bearings impregnated with oil; the only change being that the specific gravity at loo per cent oil will be 0.89 if we assume that that is the specific gravity of the lubricant. The curve is useful in determining the oil content by volume for any specific gravity. The normal range of oil content for porous bronze bearings of this composition is from 35 to 16 per cent, which is in the specific gravity range of from 5.8 to 7.3. In addition to the amount of porosity, the type of porosity is important. The first consideration here is that the porosity must be intercommunicating. This can be determined by a number of simple tests. The first method, which is very accurate, is to extract the oil in the bearing by cycling

Jan 1, 1945

By C. E. Beecher

THE application of gas or air under pressure to obtain more oil from a sand which has been practically exhausted by ordinary production methods has been practiced to a limited extent for many years. Until recently such methods were confined to the Eastern fields, principally those of Ohio and West Virginia, where in many cases the production obtained after applying pressure for a few years was nearly equal to the total production prior to that time which had been obtained by the usual production methods.' As early as 1917, J. 0. Lewis1 called attention to this method of increasing the recovery of oil and cited the phenomenal results obtained by H. E. Smith, I. L. Dunn and 0. C. Dunn, who pioneered the application of air or gas pressure recovery methods. With this information available it would appear that other oil-producing sections of the country have been extremely slow to realize the advantages of repressuring. However, after a few successful projects in the Mid-Continent area, the oil producers appreciated the value of this method for obtaining further and profitable production from their practically exhausted leases and are now making extensive use of it. In general, it has been the practice to apply pressure to the sands when production has declined to a small yield per well. The purpose of this paper is to discuss some of the advantages which may be expected from returning gas under pressure to the oil sands during the early stages of development, before the rock pressure has been dissipated and the gas exhausted, and to stimulate discussion of this subject on which comparatively little actual field data are available.

Jan 1, 1928