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By James F. Kemp

The iron ores of southeastern Cuba present a subject of exceptional geological interest. Their relations to the inclosing rocks are varied and in some cases unusual. The problem of their geological origin is not a simple one and for this reason has occasioned some divergence of views among previous observers. Profiting, however, by these earlier studies and by more detailed field and laboratory observations as well as by the experience of added years of mining, much more satisfactory descriptions and interpretations can now be prepared. Previous Work In 1884, interest in the southeastern coast of Cuba became active among the consumers of iron ore along the Atlantic seaboard of the United States. Active development was undertaken by the Juragua Iron Co., Ltd., a corporation affiliated with the Bethlehem Steel Co., and the Pennsylvania Steel Co. The property of the Juragua company, which is situated about 15 miles east of Santiago, was studied in June and July, 1884, by Dr. James P. Kimball, at the time Professor of Economic Geology in Lehigh University and one of the best known of American mining geologists. Dr. Kimball published on his return two papers, the first important descriptions which we have of the local geology.1 It is

Jan 1, 1916

By David B. Reger

Exploration for new pools of gas in the Oriskany sand and continued exploitation of areas already known to be productive in that sand were the main features of petroleum activity in West Virginia during 1938. To a considerable extent the exploration program resulted in failure, but the extension of former areas was eminently successful. Throughout the state, in general, less drilling was done than in 1937. According to the West Virginia Department of Mines, only 631 permits to drill were issued, as compared to 1034 in 1937. The account of operations, as reported by trade journals and other sources, shows that 766 wells were drilled, resulting in 131 oil wells with 1609 bbl. of daily production; 484 gas wells with 1,232,216,000 cu. ft. of daily open flow; and 151 dry holes. Several discoveries indicate new pools of oil and gas; and several extensions of old gas pools have been made. In spite of a decreased number of total wells, the figures for new gas and oil are both larger than in 1937. The new oil average is 12.3 bbl. per well per day; the gas average is 2,545,900 cu. ft. per well per day, the ratio of dry holes to completions is 19.71 per cent. No general attempt was made to discover new pools of oil. A continued low price, coupled with reduced takings, combined to make drilling unattractive. The principal oil wells completed, by counties are: Boone, 6; Calhoun, 10; Clay, 7; Gilmer, 5; Kanawha, 5; Lincoln, 7; Pleasants, 13; Ritchie, 32; Roane, 6; Tyler, 7; and Wirt, 14. Production for the year, according to the Oil and Gas Journal, was 3,724,750 barrels. The leading counties in gas, with the number of successful wells in each, are: Boone, 16; Braxton, 13; Cabell, 47; Calhoun, 29; Doddridge, 10; Gilmer, 55; Kanawha, 127; Lincoln, 18; Ritchie, 29; Wayne, 19; and Wetzel, 26. Production for the year is estimated as 150,000,000,000 cubic feet. Pipe-line construction, which was extensive in 1937, was insignificant in 1938. Exploration was not as active as in 1937. Field prices of both oil and gas have severely declined.

Jan 1, 1939

By David B. Reger

Exploration for new pools of gas in the Oriskany sand and continued exploitation of areas already known to be productive in that sand were the main features of petroleum activity in West Virginia during 1938. To a considerable extent the exploration program resulted in failure, but the extension of former areas was eminently successful. Throughout the state, in general, less drilling was done than in 1937. According to the West Virginia Department of Mines, only 631 permits to drill were issued, as compared to 1034 in 1937. The account of operations, as reported by trade journals and other sources, shows that 766 wells were drilled, resulting in 131 oil wells with 1609 bbl. of daily production; 484 gas wells with 1,232,216,000 cu. ft. of daily open flow; and 151 dry holes. Several discoveries indicate new pools of oil and gas; and several extensions of old gas pools have been made. In spite of a decreased number of total wells, the figures for new gas and oil are both larger than in 1937. The new oil average is 12.3 bbl. per well per day; the gas average is 2,545,900 cu. ft. per well per day, the ratio of dry holes to completions is 19.71 per cent. No general attempt was made to discover new pools of oil. A continued low price, coupled with reduced takings, combined to make drilling unattractive. The principal oil wells completed, by counties are: Boone, 6; Calhoun, 10; Clay, 7; Gilmer, 5; Kanawha, 5; Lincoln, 7; Pleasants, 13; Ritchie, 32; Roane, 6; Tyler, 7; and Wirt, 14. Production for the year, according to the Oil and Gas Journal, was 3,724,750 barrels. The leading counties in gas, with the number of successful wells in each, are: Boone, 16; Braxton, 13; Cabell, 47; Calhoun, 29; Doddridge, 10; Gilmer, 55; Kanawha, 127; Lincoln, 18; Ritchie, 29; Wayne, 19; and Wetzel, 26. Production for the year is estimated as 150,000,000,000 cubic feet. Pipe-line construction, which was extensive in 1937, was insignificant in 1938. Exploration was not as active as in 1937. Field prices of both oil and gas have severely declined.

Jan 1, 1939

By Henry Emmett Gross

Two types of decline curves are considered and their applications are discussed. The first is the well-known semilogarithmic decline curve having the rate of production plotted on the logarithmic scale and the time on the horizontal scale. The other curve is the percentage of oil in the fluid versus cumulative production, and it is plotted on Cartesian coordinate paper. These curves are illustrated by carefully and adequately labeled graphs. Where conditions permit application of both types of curves for rationally determining the reserves of a well, both should be applied and the most conservative reserve should be chosen. Formulas are given for determining the economic limits. For a semi-l~~arithmic~decline curve the formula is: A = B X C X D X E X F or B = A/C ? D X E X F A = total monthly operating cost (average of past year), B = economic limit in barrels of oil per day, C = days in an average month = 30.4, D = market price of crude per barrel, E = 1-royalty, F = 1-gross production tax, G = water production in barrels per day at the economic limit, H =per cent oil in fluid at economic limit. The economic limit for a per cent oil in the fluid curve is: H = B/B+G X 100 The semilogarithmic decline curve is treated first. Straight-line extrapolations on semilogarithmic paper follow the compound interest compound discount law, hence the ensuing formulas derived from this law may be used in computing reserves for such extrapolations: [1___1/(1+Y)]

Jan 1, 1939

By Henry Emmett Gross

Two types of decline curves are considered and their applications are discussed. The first is the well-known semilogarithmic decline curve having the rate of production plotted on the logarithmic scale and the time on the horizontal scale. The other curve is the percentage of oil in the fluid versus cumulative production, and it is plotted on Cartesian coordinate paper. These curves are illustrated by carefully and adequately labeled graphs. Where conditions permit application of both types of curves for rationally determining the reserves of a well, both should be applied and the most conservative reserve should be chosen. Formulas are given for determining the economic limits. For a semi-l~~arithmic~decline curve the formula is: A = B X C X D X E X F or B = A/C ? D X E X F A = total monthly operating cost (average of past year), B = economic limit in barrels of oil per day, C = days in an average month = 30.4, D = market price of crude per barrel, E = 1-royalty, F = 1-gross production tax, G = water production in barrels per day at the economic limit, H =per cent oil in fluid at economic limit. The economic limit for a per cent oil in the fluid curve is: H = B/B+G X 100 The semilogarithmic decline curve is treated first. Straight-line extrapolations on semilogarithmic paper follow the compound interest compound discount law, hence the ensuing formulas derived from this law may be used in computing reserves for such extrapolations: [1___1/(1+Y)]

Jan 1, 1939

By A. U. Seybolt, C. H. Mathewson

As is well known, many questions affecting the properties and uses of a metal cannot be answered without careful consideration of the state of purity realized in the various operations of preparation, refining, or special treatment that have brought the product to its final state. The occurrence of an impurity in minute quantity offers no guarantee that its effect will be inconsiderable because dissolved substances often modify the properties of a metal quite out of proportion to their concentration. In such cases the determination of solid solubility must be accepted as a problem of considerable difficulty, requiring the use of especially purified materials and methods not ordinarily used in the metallurgical laboratory. This aspect of the equilibrium between metals and their oxides is especially important and a search for fundamental data reveals little except conflicting opinion even concerning the systems of common occurrence and interest. Rhines and Mathewson1 in 1934 studied the solubility of oxygen in solid copper by annealing to equilibrium in air and gave reasons for the failure of other methods, notably the ordinary procedure of heat-treatment followed by microscopic examination, to yield reliable results. In this paper, a similar study has been made of the solubility of oxygen in cobalt. The simple theory of this method is outlined below.

Jan 1, 1935

CHARLES H. FULTON (author's reply to discussion*).-Mr. E. E. Thum is kind enough to point out an apparent discrepancy between the conclusions drawn from experiments and the results of those experiments. It is stated on page 1383 that carbon dioxide in excess of 1 per cent. is not found in the gases above the carbon reduction temperature (of zinc oxide). This statement refers to such temperatures as occur in ordinary zinc distillation and is not meant to include temperatures above 1350° C., and it should have been so stated in the original paper. When the temperature of the distilling chamber reached 1400° and above, it was noted that the amount of carbon dioxide in the gases increased. This cannot be explained by the equilibrium of the reaction 2CO?CO2 + C, and in seeking reasons for the discrepancy, the experiments of Meyer

Jan 1, 1919

Discussion of the paper of L. W. BAHNEY, presented at, the New York meeting, February, 1915, and printed in Bulletin No. 9S, February, 1915, pp. 339. to 344. E. J. HALL,* New York, N. Y. (communication to the Secretary+).- The Chiddy method for determining gold and silver in cyanide solutions has been subjected to so many proposed modifications, of which L. W. Bahney's is one, it is natural to suppose the method is defective. There is no denying that this method is capable of giving inaccurate results, but so is any other method of quantitative determination. However, proof has not come to my notice that the troubles are inherent and not in the detail application, and I am inclined to think from our experience that in many cases it is the latter. Errors in this method may be occasioned by: (1) The retention of zinc in the sponge, which tends to desilverize the molten lead in cupellation, similar to the action in the Parkes process, removing gold and silver in a crust of zinc oxide. Failure to remove zinc may result from lack of concentration of hydrochloric acid, clue to neutralization by salts present, volume of liquid too great for the specified amount of acid, or the use of weak acid. (HCl rapidly loses its strength unless kept in perfectly tight containers. The HCl gas escapes even from the ordinary glass-stoppered acid bottles after the plaster seal has been broken.) Undissolved zinc, is likely to be held in the upper part of the lead sponge, which floats above the liquid, and unless the solution is boiled it will escape action. Mr. Bahney's modification makes this

Jan 5, 1915

By L. A. Wright, J. F. Emerson

The Pine Creek mine, owned by Union Carbide Nuclear Co., Div. of Union Carbide and Carbon Corp., is one of the world's largest producers of tungsten. The mine is located on the eastern slope of the Sierra Nevada Mountains, about 25 miles north- west of Bishop, Calif. Prior to 1948, production from the property came either from surface pits or from underground workings above A level haulage tunnel. The tunnel is at an elevation of 10,900 ft, which left 500 to 600 ft of vertical backs to the surface outcrops. Heavy production demands during World War II hastened the planning for long range development of orebodies below A level. A 7000-ft haulage tunnel, 1500 ft below A level, was started in 1943 and completed in early 1947. This haulage tunnel is at an elevation of 9400 ft and is known as Zero tunnel.

Apr 1, 1956

By AIME AIME

WITH a brilliance undimmed by hard times, the annual dinner on Wednesday evening, Feb. 17, was a complete success. More than 600 members, friends and ladies gathered early and filled the anterooms of the grand ballroom of the Commodore Hotel, while the president's reception was in progress, and then at the sound of the gong and with the music of the orchestra, rising above the happy din of conversation thronged to their seats at the tables. Following the "potage Ambassadeur"-probably to eliminate a very real hazard-the usual toy balloons appeared and a gay and lively scene, punctuated by multitudinous explosions, ensued, as the hundreds, of variously colored spheres bounced yon and hither until their gaseous existence was ended on the glowing end of a cigar or cigarette. On the speakers' dais sat C. E. Beecher, Chairman Petroleum Division; J. Vipond Davies, representative of A. I. M. E. on the Alfred Noble Prize Committee; Corbin T. Eddy, Alfred Noble Prize recipient; A.' S. Tuttle, Vice-president American Society of Civil Engineers; W. C. Mendenhall, Director U. S. Geological Survey; George C. Bateman, representing the Canadian Institute of Mining and Metallurgy; Paul D. Merica, Institute of Metals lecturer and Chairman James Douglas Medal Committee; Champion Herbert Mathewson, James Douglas Medalist; Robert E. Tally; retiring President; G. Temple Bridgman, toast-master; Scott Turner, incoming President; F. W. Bradley, William Lawrence Saunders Medalist; Fred Searls, Jr., Chairman William Lawrence Saunders Gold Medal Committee; Arthur Notman, President Mining and Metallurgical Society of. America; Robert J. Grant, Director U. S. Mint; Landon F. Strobel, Chairman New York Section; Howard Scott, recipient of Robert W. Hunt Prize; George. B. Waterhouse, Chairman Robert W. Hunt Prize Committee; F. M. Becket, Chairman Iron and Steel Division; Ora E. Clark, recipient of the J. E. Johnson, Jr., Award; Richard Peters, Jr., Chairman J. E. Johnson, Jr., Award Committee; E. C. Bain, Howe Lecturer; Sam Tour, Chairman Institute of Metals Division; and H. Foster Bain, Chairman. Charles F. 'Band Foundation Committee. ' Each was heartily applauded when introduced by Mr. Bridgman, as was Mrs. Tally, who also made a bow. The toastmaster made graceful reference in introducing Mr. Strobel, to the large part the latter had taken in planning the meeting.

Jan 1, 1932

By A. U. Seybolt

As is well known, many questions affecting the properties and uses of a metal cannot be answered without careful consideration of the state of purity realized in the various operations of preparation, refining, or special treatment that have brought the product to its final state. The occurrence of an impurity in minute quantity offers no guarantee that its effect will be inconsiderable because dissolved substances often modify the properties of a metal quite out of proportion to their concentration. In such cases the determination of solid solubility must be accepted as a problem of considerable difficulty, requiring the use of especially purified materials and methods not ordinarily used in the metallurgical laboratory. This aspect of the equilibrium between metals and their oxides is especially important and a search for fundamental data reveals little except .conflicting opinion even concerning the systems of common occurrence and interest. Rhines and Mathewson1 in 1934 studied the solubility of oxygen in solid copper by annealing to equilibrium in air and gave reasons for the failure of other methods, notably the ordinary procedure of heat-treatment followed by microscopic examination, to yield reliable results. In this paper, a similar study has been made of the solubility of oxygen in cobalt. The simple theory of this method is outlined below.

Jan 1, 1935

By William T. Folwell

The Lucky Friday mine east of Mullan, Idaho, is an outstanding example of a property in the Coeur dlAlene district where a small and insignificant-appearing silver-lead-zinc vein at the surface has changed at depth into a large vein of great importance. The Lucky Friday vein has little if any surface expression and above the 1200 level the ore shoots are small and discontinuous. Between the 1200 level and 2450 level, the lowest developed level, the main ore shoot has shown remarkable improvement on each succeeding lower level, and today the mine is one of the major lead-silver producers in the Coeur d'Alene district. History: The Lucky Friday property is on the north side of the South Fork of the Coeur d'Alene River in sections 25, 26 and 35, T. 48 N., R. 5 E., Hunter mining district, Shoshone County, Idaho. This is about one mile east of the town of Mullan, which serves the eastern portion of the Coeur d'Alene district. The southern part of the property is crossed by a branch line of the Northern Pacific Ry. and by U. S. Highway 10. This highway is the principal road crossing the panhandle of Idaho and connects the district with Spokane, Wash., on the west and Missoula, Mont., on the east. The main portal and surface plant of the Lucky Friday mine is at an elevation of 3365 ft, only a short distance above the valley floor and a few hundred feet from U. S. Highway 10. so the mine is readily accessible for year-round operation. The property is comprised of six claims, known as the Lucky Friday group, owned outright by the Lucky Friday Silver-Lead Mines Co. There are four patented claims, Good Friday, Lucky Friday, Northern Light, and Lucky Friday Fraction No. 2 (Mineral Survey No. 3028), and two unpatented claims, Hunter and Creek. In addition, Lucky Friday owns an undivided one-half interest in the Hunter Creek property. which adjoins the Lucky Friday group on the north: a 90 pct interest in the mineral rights in the Jutila Ranch (160A), which adjoins the Lucky Friday group on the east; and a 60 pct interest in the Lucky Friday Extension claim group, which adjoins the Lucky Friday group on the west. The company also has a long-term mining lease on the Hunter Ranch, which adjoins the Lucky Friday group on the west. The claims of the Lucky Friday group were located between 1899 and 1906. The Lucky Friday Mines Co. was organized in 1906 and did considerable exploration work by surface trenching and shallow underground workings, only to see the property sold by the Shoshone county sheriff to satisfy labor claims totaling $2000 in 1912. Another firm, Lucky Friday Mining Co., bought the claims in 1914 and spent 12 years driving what is now known as the tunnel level crosscut. This tunnel intersected a vein previously exposed in a higher tunnel, but it was only a few inches wide. The vein was followed a short distance westerly but was so unpromising that the work was discontinued in favor of extending the main crosscut tunnel several hundred feet north. No ore was found and all work was discontinued. The property was held in such low esteem by the firm that it let taxes amounting to less than $15 a year go delinquent for nine years. Then the property lay idle for two more years until in 1938 John Sekulic, a Mullan service station operator, took a lease, with a $15,000 purchase option, on the advice of an old miner who had worked in the mine. Sekulic re-opened the tunnel level crosscut and explored the vein with an easterly drift for about 200 ft. The vein was too narrow to be of commercial value but was believed interesting enough to warrant further exploration at depth. Lacking funds to explore the vein at depth, Sekulic tried to get the district's larger operating companies to take over his lease and option. They were not interested because of the lean tunnel level showing and the fact that the property lay between the White Ledge fault on the north and Osburn fault on the south, an area which geologists always considered unworthy of exploration. Sekulic then organized the present company and assigned his lease and option to it for stock. This was in 1939. Enough stock was sold locally to finance sinking of a shaft 100 ft from the tunnel level east drift. The vein at this additional depth still was not commercial but showed some improvement. Treasury stock was offered at 5 to 10C a share

Jan 1, 1959

By F. C. Greene

The oil and gas industry in Missouri in 1934 continued along the same lines that have marked the previous years. One new gas pool has been opened, others have been extended and in one oil pool a 25-bbl. well was completed. Missouri has no laws or regulations relating to drilling or the filing of well logs and the Geological Survey depends on its own scouting activities to obtain information. The data herein have been taken largely from a paper by the author recently published in the 58th Biennial Report of the State Geologist of Missouri. That report is available on application to H. A. Buehler, State Geologist, Rolla, Missouri, accompanied by ten cents in stamps, the amount of the postage. The preliminary figures, subject to revision, indicate that before the end of December, 1932, there were 2495 completions, of which 320 were oil wells, 1139 were gas wells and 1036 were dry. Over half of the oil wells were drilled in the Richards-Stotesbury area of Vernon County and were pumped for only a short period of time. During the period 1933-34 there were 201 completions, of which 10 were oil wells with an initial daily capacity of 100 bbl., 90 were gas wells, with an open flow of 26,578,256 cu. ft., and 101 were dry. The most active areas in drilling for gas in 1934 were the Marota area, sec. 17, T.49N., R.32W., Jackson County, the Grandview area in T.47N., R.33W., Jackson County, and the Plattsburg area in Clinton County. The Knoche oil pool in sec. 16, T.46N., R.33W., Cass County, was the scene of the only important oil development. In the Marota pool nine wells were completed to the Squirrel sand, with a combined open flow of about 5,000,000 cu. ft. The pool is on a small symmetrical dome with a closure of at least 30 ft. The average depth of the wells is 450 ft. The Squirrel sand (Upper Cherokee, Pennsylvanian) had a thickness of 94 ft. in a near-by dry hole, but only the upper 30 or 40 ft. is drilled in the producing wells. The largest well

Jan 1, 1935

By E. B. Branson

Introduction to Geology, by E. B. Branson, W. A. Tarr, and W. D. Keller, revised-by Carl C. Branson. McGraw-Hill, 1952. $5.50.-Dealing with physical and historical geology, the book has been revised from an earlier edition. An attempt has been made to eliminate unnecessary detail in discussing processes and history. Revisions bring technical and statistical data up-to-date, and follow suggestions by teachers who used earlier editions. The book carries an eye witness account of the severe earthquake in Assam, India, in 1950 and the story of Paricutin and other major examples of volcanism. Charts summarize chemical weathering, and the results of metamorphisms. The book also contains many new illustrations, including aerial photographs. A History of Phelps Dodge 1834-1950, by Robert Glass Cleland. Alfred A. Knopf, 1952. $4.00.-The book traces the growth of Phelps Dodge from the day Anson Greene Phelps opened a small saddle shop in Hartford, Conn., to the present day. As the country grew, so did Phelps Dodge. The company took part in large affairs from its very beginning. It bought and sold, exported and imported, built factories and railroads, and widened its scope of operations economically and geographically. Entrance of Phelps Dodge into copper mining and the gradual giving up of other interests in favor of the new venture is traced.

Jan 1, 1952

By Evan Bennett

ALMADEN is Arabic for "the mine." The definite article is properly used, for no mercury mine in the world compares with it for richness and volume of ore, produced and potential. After more than twenty centuries of exploitation, intensive throughout the last lour, ore from Almaden is about five times as rich as that of its closest competitor. We drove to the mine one April afternoon, across Don Quixote's plains of the Mancha, up the bleak, arid valley of the Rio Valdeazogue where we passed tenth century Moorish workings and their ruined castles. At dusk, we came to the Hacienda de Castilseras, a large farm where Almaden miners work their land on off days. Then we drove through the whitewashed, well-ordered town to the Castillo de la Direccion where we were challenged at the iron gate by two picturesquely costumed Guardias Jurados.

Jan 1, 1948

By W. Armstrong Price

INVESTIGATION by German chemists during the World War showed that particles of iron oxide form rapidly in iron pipes carrying hydrogen gas under pressure when the gas contains small amounts of water. Under these conditions, the gas frequently exploded when expanding into a dirigible. The explanation of the explosions lies in the building up of a charge of static electricity in the flow just beyond the orifice and the ignition of the gas by a spark accompanying discharge of the electricity. Friction between the moving particles and the pipe generated the electric charge, which was manifested by a pale blue glow formed in the flow at pressures above two atmospheres. In one experiment, this glow, at eighty atmospheres, extended for a distance of forty to fifty centimetres, but did not ignite hydrogen and air mixtures until the charge was col-lected by a conductor and discharged across a gap between electrodes placed at the side of the column of gas. Autoignition did not occur when this discharge was effected at a distance from the gas column, nor if the gas used was thoroughly dried and free from impurities. The electric charge has been studied by placing various wire and screen conductors in the outcoming stream of gas, Guest having summarized these experiments. The application of these conclusions to fires in petroleum and natural gas issuing uncontrolled from wells is made in the following paper, citing the ignition of a wild gas well in Texas.

Jan 1, 1936

COUNCIL OF SECTION DELEGATES A J Duff G H Ruggles E D Gardner E H Torgersen F W Strandberg, Chairman W I Garms H C Weed R D Chapman, Vice-Chairman H M Lavender J A Wilcox F T Moyer. Secretary W C Lawson C F Willis EXECUTIVE COMMITTEE J E Kastrop L Thiessen Past Chairmen R H Smith E H Wisser P D I Honeyman R W Hughes C H Kuzell

Jan 1, 1951

By William N. Poundstone

To forecast the future of coal intelligently, one must first consider the market outlook. Coal can be used for many purposes, but currently about 25% of it goes into metallurgical coke, while 75% serves as fuel. Coal for metallurgical coke should show a modest growth for at least the next decade, primarily because of increased exports, but the important factor in the coal outlook is energy. Today, this country faces a serious shortage of energy, and its requirements are growing at an almost unbelievable rate. Last year the United States consumed 68 quadrillion Btu, or double the energy it consumed in 1950, and, if projections are correct, this figure will grow to 150 quadrillion Btu by 1990. Thus, in one working lifetime, the nation's energy consumption is expected to increase by roughly five times. The future of coal hinges on its degree of participation in meeting this energy need. The Federal Power Commission predicts that coal consumed by electric utilities will increase about 4-576 per yr, reaching 472 million tons by 1980 and 615 million tons by 1990. If this projection proves correct, 1980 consumption will be double that of last year and, even more startling, the utility industry alone will use more coal in 1990 than the entire coal industry produced in 1970. This is a tremendous increase, but in view of the projected energy growth, it is difficult to see how this country's needs can be satisfied with- out a coal contribution of this magnitude. Unless some new source such as solar energy is discovered, it must be assumed that the projected energy will come principally from the present-day sources-oil, gas, nuclear materials and coal.

Jan 1, 1971

By Francis B. Foley

In examining steel under the microscope, one is constantly confronted with structures that are difficult to interpret. Recently, in a collection of samples for exhibition purposes, the writer found a piece of open-hearth runner metal, 2 in. (50 mm.) in diameter, that had been fractured for use as a sample of cast-steel structure. On polishing and etching a section for the purpose of photographing a field to typify the microstructure of steel in the "as cast" condition, a variety of structures was found (Fig. 1) so arranged as to arouse interest at once. For a distance of about 0.065 in. (1.6 mm.) from the skin of the runner, normal ingot structure was found (Fig. 2); this was followed by a zone, about 0.215 in. (5.5 mm.) wide, of considerably lower carbon content in which occurred a most pronounced Widmannstattian structure (Fig. 3); from this point on to the center of the runner, the metal was again of normal ingot structure (Fig. 4). Representative samples taken from the metal in the three zones showed the following analysis: Carbon Nickel Chromium Per Cent. Per Cent. PeR Cent. Metal from skin........................... 0.34 1.26 0.63 Widmannstattian zone.................... 0.21 1.18 0.63 Metal from center......................... 0.34 1.32 0.67 Such a condition might result from decarburization followed by recarburization of the skin. This section came from one of the branch runners to the bottom of the mold, not from the main runner, and it is difficult to conceive of decarburization occurring in this portion of a runner. If the metal were stripped while quite hot, some oxidation would take place but the recarburization is unaccounted for. It could not occur by segregation after solidification—the tendency then is for diffusion and homogeneity. The following seems to fit the conditions and is offered as an explanation. The outside layer of normal structure 0.065 in. (1.6 mm.) thick was chilled on the walls of the runner brick when the molten metal first entered the runner. As the molten metal flows by, the outside of the stream

Jan 1, 1920

By Roy C. Kirkman

Dear Editor: It is with great pleasure that I read Mr. Howard M. Wells article in the December 1978 issue of MINING ENGINEERING entitled: "Optimization of Mining Engineering Design in Mineral Valuation." Mr. Wells very adequately presents the case and point that there are a great number of variables which must be analyzed during an economic evaluation of an FUND RESOURCE, such as copper or uranium. I wish to take this opportunity to suggest that, given today's economic climate, decision making takes place under conditions of uncertainty and that this uncertainty justifies our need to examine each one of the parameters entered into the evaluation model. It is my contention that the influence of the tonnages and grades as well as their distributions, have the most profound effect upon the results of an evaluation. Everyone concerned with the evaluation of FUND RESOURCES realizes that as metal prices decline or stagnate with sharply rising direct operating costs, cutoff grades (Gc) must increase according to the equation below which Mr. Wells uses: Gc = Total Operating Cost/(Market Price X 20 X Recovery) However, historically, we have seen cutoffs move dramatically lower in both the copper and uranium industries for the past decade. Henceforth, this established the metals industry most important argument for processing greater tonnages of lower grade materials from disseminated deposits (refer to paper by Kirkman, Roy C.). These disseminated deposits, created by either concentration processes (uranium) or dispersion processes (copper, gold, molybdenum), have log-normal grade distributions (Fig 1). Gross profits are rising, but unit profits are falling. The industry has created longevity through economy of scale, i.e., mining vast tonnages of low grade. In order to develop the great tonnages necessary to prove economic viability, we must examine alternatives at the low-end of the tonnage grade relationship. Notice from [Fig. 2] that as we move further to the right away from line A-B drawn tangential to the average grade curve at 45°, total profits will increase (given fixed annual production capacity) and unit profits decrease. The theoretical optimum operating point is where: [ ] At this point my observation is that slight shifts in production capacity bring about greater changes in profitability due to greater grade changes. Therefore, the best financial risk evaluation is obtained by totally revising the mining engineers methods and fixing the financial parameters such as discount and interest rates. A 10% shift in either of these two parameters will not cause near the same variance in economic viability as will a change on the GRADE-TONNAGE curve [(Fig. 2)].

Jan 1, 1980