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By Clifford Frondel

THE aluminum oxide known as corundum has several varieties that have been used as gem materials since ancient times. These include the red variety called ruby, the blue variety sapphire, and the asteriated types of ruby and sapphire. Asteriated sapphire was known to the ancients under the name of astrios, and descriptions of this gem were given by Pliny and other early writers. The relation of these gem materials to each other as varieties of a single species, corundum, was first clearly established by Haüy in 1805 and J. M. Güthe1 in 1809. Natural gem corundum is obtained principally in Ceylon, Siam, Burma, India, and Australia. Star sapphires and rubies always have been highly prized and in recent years have become particularly popular in the United States. Natural star rubies of large size and fine quality are extremely rare and rank with large and fine emeralds and diamonds as the most valuable of gem stones. Interest thus attaches to the recent success in commercially synthesizing star sapphires and rubies of a size and perfection unmatched by nature.

Jan 1, 1954

By Kenneth Cottingham

The number of wells completed in Ohio during I940 was about 20 per cent more than during the preceding year, the comparative totals being 1020 and 1228. Of the 1940 completions, 327 were oil wells, 491 gas wells, and 410 dry. The completions for the past five years, divided into oil wells, gas wells, and dry holes, are shown in Table 2. Wells drilled deeper and input wells in water-flood areas are not included in the tabulation. The annual production of oil has decreased steadily in Ohio from the maximum of 23,941,000 bbl. produced in 1896. Table 3 shows the quantities of oil produced in the last five years. In 1940, the total was 3,052,000 bbl., produced by about 25,500 wells. The number of wells and the approximate quantities by grades are shown in Table I. Table i ,—Tabulation by Grade Grade 1 2 Barrels __________________________________________________________________________________________ Pennsylvania ............. . 1,198,000 Lima.................... . 325,000 Corning................... 3,730 1,159,000 Lodi...................... T,040 350,000 Cleveland................. 30 1:1,000 Total................... 25,500 3,052,000 The prices paid for Ohio crude oil in 1940, together with dates of changes in posting, are shown in Table 4. The production of natural gas in 0hio has declined from a maximum of 79,510,032 M cu. ft. in I9I5 S to 36,469,000 M cu. ft. in 1939, the most recent year for which a figure is available. Consumption reached its peak in Ohio in the year 1916, when it was 169,480,01r M cu. ft., declining to 114,720,ooo M CU. ft. in 1939. The produc-tion and consumption of natural gas in Ohio for the past five years are shown in Table 5. TAble 2.—Completions in Ohio during Past Five Years Numbs of Wells Drilled during Year YearI, ] Oil Gas Dry Total 1936............. 263 570 324 1,157 1937............. 317 503 45I 1,271 1938............. 189 433 288 gro 1939............. I70 501 349 1,020 19391940............. 327 491 410 1,228 Total.......... 1,266 2,498 1,822 5,586 Table 6 shows the number of oil wells and the number of gas wells completed by sands during 1940, with the average initial production per well for each sand. Table 7 shows the total number of wells drilled—oil, gas and dry—by sands. Development during 1940 Szth-Trenton.—For several years, considerahle interest has been shown in a horizon lying some 500 to 700 ft. below the top of the Trenton, known to the driller in western Ohio as the "green sand," and in eastern Ohio as the St. Peter. In 1939, ten 'lgreen sand" tests were drilled, all in western Ohio and all dry- In 19401 eight wells were drilled to this horizon, one of which was a small oil well (one barrel) in Men county- Of the remaining seven—all of which were dry-—one in Franklin County, in central Ohio, was drilled to a depth of 2903 ft. .Another was in Medina

Jan 1, 1941

By Kenneth Cottingham

The number of wells completed in Ohio during I940 was about 20 per cent more than during the preceding year, the comparative totals being 1020 and 1228. Of the 1940 completions, 327 were oil wells, 491 gas wells, and 410 dry. The completions for the past five years, divided into oil wells, gas wells, and dry holes, are shown in Table 2. Wells drilled deeper and input wells in water-flood areas are not included in the tabulation. The annual production of oil has decreased steadily in Ohio from the maximum of 23,941,000 bbl. produced in 1896. Table 3 shows the quantities of oil produced in the last five years. In 1940, the total was 3,052,000 bbl., produced by about 25,500 wells. The number of wells and the approximate quantities by grades are shown in Table I. Table i ,—Tabulation by Grade Grade 1 2 Barrels __________________________________________________________________________________________ Pennsylvania ............. . 1,198,000 Lima.................... . 325,000 Corning................... 3,730 1,159,000 Lodi...................... T,040 350,000 Cleveland................. 30 1:1,000 Total................... 25,500 3,052,000 The prices paid for Ohio crude oil in 1940, together with dates of changes in posting, are shown in Table 4. The production of natural gas in 0hio has declined from a maximum of 79,510,032 M cu. ft. in I9I5 S to 36,469,000 M cu. ft. in 1939, the most recent year for which a figure is available. Consumption reached its peak in Ohio in the year 1916, when it was 169,480,01r M cu. ft., declining to 114,720,ooo M CU. ft. in 1939. The produc-tion and consumption of natural gas in Ohio for the past five years are shown in Table 5. TAble 2.—Completions in Ohio during Past Five Years Numbs of Wells Drilled during Year YearI, ] Oil Gas Dry Total 1936............. 263 570 324 1,157 1937............. 317 503 45I 1,271 1938............. 189 433 288 gro 1939............. I70 501 349 1,020 19391940............. 327 491 410 1,228 Total.......... 1,266 2,498 1,822 5,586 Table 6 shows the number of oil wells and the number of gas wells completed by sands during 1940, with the average initial production per well for each sand. Table 7 shows the total number of wells drilled—oil, gas and dry—by sands. Development during 1940 Szth-Trenton.—For several years, considerahle interest has been shown in a horizon lying some 500 to 700 ft. below the top of the Trenton, known to the driller in western Ohio as the "green sand," and in eastern Ohio as the St. Peter. In 1939, ten 'lgreen sand" tests were drilled, all in western Ohio and all dry- In 19401 eight wells were drilled to this horizon, one of which was a small oil well (one barrel) in Men county- Of the remaining seven—all of which were dry-—one in Franklin County, in central Ohio, was drilled to a depth of 2903 ft. .Another was in Medina

Jan 1, 1941

By H. A. Guess

For a number of years I have used for the commercial wet assay of lead generally the ammonium molydate, and occa-sionally the ferrocyanide method. These well-known methods need no detailed description here. In the ore-selling and ore-buying establiahments of the West, 90 per cent. of all wet lead-assays are made by one or the other, and at least nine-tenths of this proportion by the molybdate method. A procedure so well-established must have merit; and, in

Jan 1, 1905

By William Plank

IN PAST YEARS, engineering educators and others have been able to study the problems relating to en-gineering education in the United States with only inadequate and, frequently, inaccurate data at their command. For the first time there is now available fairly full and accurate information on this subject, gathered and compiled by the Board of Investigation and Coordination of the Society for the Promotion of Engineering Education. This board, of which W. E. Wickenden is the director, has for the past four years been carrying out fact-finding investigations into "the objects of engineering education and the fitness of the present day curriculum," under a grant of funds from the Carnegie Corporation of New York. Twelve bulle-tins have already been published by the board and others are in the process of preparation. The studies made, thus far, have been of the various phases of engineering education in general as well as of the major branches of engineering. Within the past year. the board has completed a study of mining engi-neering education by means of a questionnaire sent to members of the Institute. A special committee, con-sisting of Charles E. Locke, Allen H. Rogers and the writer, cooperated with the board in drafting certain parts of the questionnaire and in selecting the mailing list. Similar studies have been made through the mem-bers of the four other national societies. The results of these studies have been published only in mimeo-graphed form, therefore, in order to place the data before the members of the Institute an incomplete sum-mary of the replies to the A. I. M. E. questionnaire is here given. The full report will be available for distri-bution at the annual meeting in February. The questionnaire was sent to 306 members of the Institute, a proportion about equal to the proportion of the membership of the other national societies can-vassed; 152 members replied to the questionnaire, 55 per cent of whom had received college degrees in some branch of engineering connected with the mineral in-dustry. Forty-seven educational institutions were rep-resented in the replies. Seventeen different positions were held by the members who replied, with 24 con-sulting engineers at the head of the list, 20 managers, 16 superintendents, 11 presidents, 10 professors, 6 deans, and others.

Jan 1, 1928

By W. B. Coleman

Considerable discussion on the effect of iron and steel scrap in blastfurnace burdens was presented in the January, 1927, issue of Mining and Metallurgy. Therein the question is asked as to what causes the difference in physical properties of pig irons where the chemical analyses are practically the same. This point no doubt has been noticed by a number of furnace operators, but several years ago very little thought was given to it. The foundries purchased pig iron, had it analyzed and found it to be within their specification. The castings made from this iron at times would be satisfactory and at other times hardness and shrinkage would occur. Since the iron was chemically correct the foundries generally were at a loss as to what to do. They changed their method of melting in the cupola and in some cases this corrected the trouble. In some instances the foundry would continue eliminating a brand of iron until the castings produced were satisfactory. Through this process of elimination they would finally arrive at the conclusion that a certain brand of iron was causing the trouble. During the course of this elimination minor changes might have been made in the melting and in the end satisfactory castings were secured without discovering any definite reason for the trouble. Frequently the foundries blamed the manufacturer of the pig iron although the seat of the trouble was in their own method of melting. I have in mind one foundry in particular that was using three brands of pig iron for producing their castings and their losses were rather high. Three entirely new brands of iron were substituted in the charge and still the losses continued. Even after using six brands of pig iron the management felt that the pig iron was the cause. The difficulties encountered in the melting of iron in the cupola, over the past several years, reflect in a great many cases on the operation of the cupola. At different times certain brands of iron were unsuitable for producing a certain class of castings, but at the same time one could see no reason why the iron should be considered abnormal. Irons from furnaces where production and low cost are the main factors that are being used in foundries produce in most cases harder cast-

Jan 1, 1927

By James A. Lewis

It is the purpose of this paper to show the importance of sand characteristics, when combined with other physical data, in evaluating production obtained by secondary recovery operations, and to indicate the benefits to be gained from the application of these principles to primary production.

Jan 1, 1942

By F. V. Shallcross

Physical properties of thin films of CdS and CdSe formed by vacuum deposition onto glass sibstrates have been studied as a function of deposition and processing conditions. The crystallinity and surface features of CdS films were examined using electron microscopy and electron and X-ray diffraction techniques. The films were poly crystalline; the preferred orientation and crystallite size increased with film thickness, substrate temperature, and deposition time. The CdS films consisted primarily of hexagonal-phase material, in contrast to similarly prepared CdSe films which have previously been observed to contain mixtures of cubic and hexagonal phases. As-deposited CdS films showed no major dependence of Hall mobility on crystallite size or degree of preferred orientation. Hall mobility and carrier concentration in CdS and CdSe .films were measured at various temperatures; both parameters increased with temperature and yielded activation energies which depended on fabrication conditions. Surface-desorption phenomena and overcoating of the semiconductor with SiO affected the observed electrical properties significantly. THIN films of cadmium sulfide1,2 and cadmium sele-nide3,4 have been employed by various workers as semiconductors in the insulated-gate thin-film field-effect transistor, known as the TFT. These devices are most commonly made by vacuum deposition of all materials onto an amorphous substrate such as glass. A knowledge of the microstructure and electrical properties of semiconductor layers used in the thin-film transistor is essential in order to form a realistic model for the device and to improve its performance, reproducibility, and reliability. This paper will describe studies of the physical properties of vacuum-deposited CdS and CdSe films prepared under various conditions. Structural characteristics examined in- cluded phases present, crystallite size, nature of preferred orientation of crystallites, surface roughness, and structural homogeneity throughout the film thickness. Electrical properties measured were Hall mobility and conductivity and their dependence on temperature and ambient. Thin-film properties are affected by many fabrication parameters including purity and physical form of evaporant, deposition rate, film thickness, design and temperature of the evaporation crucible, geometry of the deposition chamber, nature of the residual atmosphere, composition and temperature of the substrate, and details of postdeposition processing. PREPARATION OF FILMS In this work the semiconductor films were deposited in a conventional oil-diffusion-pumped system with pressures in the 10-8 torr range. The CdS evaporant was obtained from the Eagle-Picher Co. as a high-purity coarse-grained crystalline powder; the CdSe was a high-purity sintered powder supplied by the Harshaw Chemical Co. The evaporation crucible was a resistance-heated molybdenum-wire basket coated with aluminum oxide and filled with a quartz wool plug at the top. The source to substrate distance was usually 10 cm. This region was enclosed by a Pyrex inner cylinder. The substrate was heated with an overlying Pyrex plate coated with tin oxide. The substrate temperature was controlled using a thermocouple attached to the lower side of the heater. This thermocouple was calibrated against another thermocouple attached to a dummy substrate and by observation of melting points of various metal films deposited in the system. The substrates were polished borosilicate glass plates and conventional glass microscope slides. Substrate preparation included cleaning with an ultrasonically agitated detergent bath followed by isopropanol-vapor de-greasing. Film thickness was measured interferomet-rically during and after deposition. STRUCTURE OF CdS FILMS Structural studies were performed on CdS films using electron diffraction, electron microscopy, and

Jan 1, 1967

By Wayne C. Hazen, James K. Kindig

As the complexity of hydrometallurgical systems increases, it offers new opportunity for applications of solvent extraction. However, the high capital cost of mixer-settlers for large flow rates is a drawback to wide application in base metal recovery. This paper presents information on the use of cyclone separators in place of settlers with attendant significant reduction in capital cost. Various flowsheet possibilities for this development are discussed.

Jan 1, 1972

By George Rice

THE A.I.M.E. Ground Movement and Subsidence Committee, pro-posed in 1920, held its first technical meeting in February 1923, under the able chairmanship of Mr. H. G. Moulton. The following list of papers and discussions, indicating the scope of the problems and relation to various conditions and method of mining, were given at that meeting by the distinguished mining engineers: J. Parke Channing, on Subsidence at Miami, Arizona; Howard N. Eavenson, on Mining an Upper Bitu-minous Seam after a Lower Seam Has Been Extracted; J. J. Rutledge, on Subsidence in Two Oklahoma Coal Mines; Benjamin F. Tillson, on Caving Cracks at the Franklin Mine, New Jersey; Dr. F. W. McNair, on the Dome Theory; William Kelly, on disadvantageous effects in Mining and Back-filling Working Upward a Steep-Fitching Iron-ore Bed; Eli T. Conner, on the good results of Back-Filling by Hydraulic Means in Preventing Destructive Subsidence in the Anthracite District; Thomas H. Claggett, on the merit of Systematic Pillar Drawing in Preventing Cracks in an Upper Seam; Henry H. Otto, successful results in the anthracite district in Mining Lower Seams before Upper Seams; Douglas Bunting, on Leading Factors Incident to Successful Mining of an Overlying Seam; Edwin Ludlow, on there being "less damage to buildings when there was complete removal of coal with complete packing than when room and pillar is used without extracting the pillars"; Edward O'Toole on "bumps" in eastern Kentucky mines, which he thought were the result of geologic stresses: H. A. Buehler, on Upheaval of Surface in an Illinois Case in Advance of the Face; and R. Dawson Hall, on The Mechanics of Subsidence from Mining. The author of this paper discussed various kinds of problems of ground movement and subsidence in both metal mining and coal mining; the production of great landslides by workings near an outcrop, as at Turtle Mountain, Alberta, Canada; and general

Jan 1, 1939

By Henning Nielsen

SIX weeks ahead of schedule, the International Nickel Co. of Canada Ltd. has brought a 30-mile rail line into the newly born town of Thompson, Manitoba. Its construction spurs the development of a rich new mining region slated to become the world's second largest nickel-producing area-exceeded only by Inco's Sudbury, Ont., workings. Two mines, the Thompson and the Moak Lake, will be opened to meet International Nickel's scheduled annual production goal of 385 million lb of refined nickel by 1961. Accomplishment of this aim will mean an additional 75 million lb of the metal available to consumers. In addition, stepped-up out- put of Inco's Sudbury holdings may increase this figure by another 25 million lb. (For an earlier report on these developments see MINING ENGINEERING News, January 1957).

Jan 12, 1957

By R. D. Pehlke, W. M. Small

The effect of added alloying elements on the solubility of nitrogen in a liquid alloy of 74 wt pct Fe. 18 wt pct Cr, and 8 wt pct Ni has been studied. At 1600°C and 1 atm nitrogen pressure, aluminum, chromium, columbium, manganese, molybdenum, tantalum, and vanadium increase the solubility of nitrogen in the liquid 18 Cr-8 Ni alloy, whereas additions of cobalt, copper, nickel, silicon, tin, and tungsten decrease the solubility. Interaction parameters based on a constant ratio of iron, chromium , and nickel have been used to quantitatively define the changes in nitrogen solubility. INVESTIGATIONS on the solubility of nitrogen in liquid iron have usually treated the pure metal, and often the influence of a single added element. Pehlke and Elliott1 carried out a comprehensive study on the influence of alloying elements on nitrogen solubility in liquid iron, and compared their results with previous studies. Turnock and pehlke2 have recently reported a study on the solubility of nitrogen in multicomponent liquid iron alloys. The original interaction parameter proposed by wagner3 was successfully employed in these studies. The need for obtaining information on the gas solubility in more complex alloys is indicated by the increasingly significant role played by dissolved gases in the processing of iron-based materials. The commercial stainless steels, for example, represent an area where data on nitrogen solubilities are required as a function of composition, temperature, and gas pressure. The nitrogen solubility in liquid Fe-Cr-Ni alloys has been studied by Humbert and Elliott.4 Their investigation covered the entire ternary system, and attempted to use data from binary alloys to predict nitrogen contents in liquid ternary alloys. Langenberg,5 using a method developed by Morris and buehl,6 calculated the nitrogen solubilities in multicomponent iron alloys from data available on binary iron alloys at 1600°C. Nelson,7 using a regular-solution model, extended this prediction to include the effect of temperature. Chipman and corrigan8 and Turnock and pehlke2 also employed empirical methods to calculate nitrogen solubilities in liquid multicomponent iron alloys. In order to provide a basis for predicting nitrogen solubility in liquid stainless steels, and to extend the data available for thermochemically modeling systems of this type, the following investigation was carried out. The study involved measupements of nitrogen solubility in a nondilute alloy and examination of the influence of a small addition of an alloying element on the nitrogen solubility. The study was focused on a very narrow range Of composition in the vicinity of 18 wt pct Cr-8 wt pct Ni (herein referred to as 18-8) with special emphasis on the change of.nitrogen solubility with the addition of a fourth metallic element. EXPERIMENTAL PROCEDURE A Sieverts' apparatus, described previously,1,2 was used in this investigation. The charge materials were contained in a recrystallized alumina crucible and inductively melted. Additions were dropped from a glass side-arm. All materials were hydrogen-refined and vacuum-treated to eliminate or minimize the oxygen content. The source and purity of materials is given in Table I. The initial metallic charge was heated to approximately 1000°C and held under vacuum for 30 to 45 min as a means for removing hydrogen and adsorbed gases. Argon was used as the calibrating gas to determine the "hot volume". The average hot volume of the system was approximately 50 cu cm STP and a few experimental runs were made using a reaction bulb with a hot volume of 80 cu cm. The temperature range studied was from 1550° to 1700°C and the temperature was measured optically. THEORETICAL PRINCIPLES General Discussion. Nitrogen dissolves in liquid iron alloys according to the reaction: 1/2N2(g) = N (wt pct in solution) [l] The equilibrium constant, K1, for this reaction is written as:

Jan 1, 1969

By C. R. Ramachandra, C. C. Patel

Flotation of chalcopyrite from a low grade ore was studied by using different xanthates and dixanthogens as collectors and by conditioning the flotation pulp with oxidizing gaseous systems. The improvement in the recovery of chalcopyrite with the oxidizing systems was mainly due to the auto-activation of chalcopyrite, leading to the enhanced adsorption of xanthates and dixanthogens even when the latter were formed by oxidation of the xanthates. With air or oxygen as oxidizing system, the amount of ethyl xanthate required at pH 8.5 was much less than normally employed in the industry, the recovery being 97-99% of chalcopyrite with a concentrate of 24% copper. With isopropyl and isoamyl xanthates, the recovery was improved but the grade was lowered. By conditioning the pulp with air-CO2 or oxygen-CO2 mixture, the recovery was lowered with ethyl xanthate only, mainly due to the depressant action of bicarbonate formed. Flotation with dixanthogens gave cleaner concentrates of chalcopyrite. because iron pyrite did not float with these collectors. Of the dixanthogens tried, diisopropyl dixanthogen gave the highest recovery, 99% chalcopyrite with a concentrate containing 28.5 to 30% copper, when the pulp at pH 8.5 was condi-tioned with air. Isopropyl dixanthogen was found to be the best collector of all the xanthates and dixanthogens studied. It was found that the adsorbed ethyl, isopropyl and isoamyl xanthates at chalcopyrite surface, activated by cupric sulfate, and at iron pyrite surface were oxidized to the corresponding dixanthogens to different degrees in presence of air, oxygen, air-carbon dioxide mixture and oxygen-carbon dioxide mixture.' The dixanthogen formed at chalcopyrite surface was, however, firmly adsorbed while that at iron pyrite surface was easily desorbed. Since dixanthogens formed have greater hydrophobicity than the corresponding xanthates, as revealed by contact angles,1,2 the former were expected to improve the flotation results. It was, therefore, thought desirable to find out the effect of air, oxygen, air-carbon dioxide mixture and oxygen-carbon dioxide mixture on the selective flotation of chalcopyrite when individual xanthates were used as collectors. The effect of direct use of dixanthogens as collectors on the selective flotation of chalcopyrite was also investigated. For these studies, low grade chalcopyrite ore, received from the Indian Copper Corp., Ltd. (I.C.C.), Ghatsila, Bihar, was employed. At the milling plant of the I.C.C., chalcopyrite is floated at a pH of 8.5, employing ethyl xanthate as collector. EXPERIMENTAL Materials Employed: XANTHATES - Ethyl, isopropyl and isoamyl xanthates of potassium were prepared in a pure state by the methods described earlier.4 A 0.03% aqueous solution of a xanthate was freshly prepared in air-free distilled water for flotation studies. DIXANTHOGENS - Diethyl, diisopropyl and diisoamyl dixanthogens were prepared by the oxidation of xanthates by iodine and purified by extraction with petroleum ether. A 0.03% alcoholic solution of dixanthogen was used as a collector. FROTHER - A 0.2% solution of pine oil in ethyl alcohol was employed. SODIUM CARBONATE - A 0.4 N solution was used. ORE - The composition of the -100 +200-mesh size (Tyler standard) powdered ore, as determined by standard methods of analysis, was: copper 1.57%, iron 10.29%, sulfur 3.15% and acid insolubles 66.10%. Iron present as chalcopyrite (CuFeS2) was 1.38%, while that present as iron pyrite (FeS,) was 1.37%. Both chalcopyrite and iron pyrite were found to be liberated from the gangue minerals and from each other, as observed under a microscope. Flotation of Chalcopyrite with Xanthates in Presence of Different Gaseous Systems: Fifteen grams of -100 + 200-mesh size ore were shaken well with 100 ml of distilled water. The pH of the pulp was adjusted to 8.5 by the addition of sodium carbonate solution. Then 0.1 ml of xanthate solution (0.005 lb xanthate per ton of the ore) was mixed with the pulp, and the latter together with washings transferred to a

Jan 1, 1963

By Robert M. Keeney

Important recent developments in the melting and annealing of non-ferrous metals include: 1. Melting of nickel silver in the vertical ring induction furnace. 2. Electric melting of stereotype metal. 3. The rotary-drum gas-fired brass melting furnace. 4. The low-frequency coreless induction furnace. 5. Finishing annealing of brass sheets with city gas1 replacing wood in the large brass-rolling mill. 6. Electric annealing of brass and copper tubing and sheets. 7. Replacement of oil by gas and electricity in the annealing of nickel-silver shells and stampings. Melting Nickel Silver in Vertical Ring Induction Furnace Although over 90 per cent. of the output of the brass rolling mills in the United States is now melted in electric furnaces,2 until recently a considerable part of the output of nickel silver has been the product of the pit fire. The application of the electric furnace to the melting of nickel silver has been slow for several reasons: (I) Until recently no lining has been available that gave a satisfactory life in the vertical ring induction furnace when melting nickel silver; (2) the rocking arc furnace so widely used in the foundry does not appear to have been favored by the rolling mill for melting nickel silver, possibly because the gases present may affect the quality of the alloy; and (3) the exclusive rights to the use of the high-frequency coreless induction furnace (which has proved very satisfactory for melting nickel silver) for the wrought brass industry are controlled by one concern. A little over one year ago the first vertical ring induction furnace to be used for melting nickel silver in the Naugatuck Valley was placed in operation. This was followed by two more in the same mill, and by

Jan 1, 1930

FOR this Famous Mining Enterprise issue MINING ENGINEERING selected the company that started the zinc in dustry in the United States. The New Jersey Zinc Co. has been a supplier of zinc products to the nation's industries for more than 104 years. Its Horse Head trade mark is famous throughout the world.

Jan 12, 1953

By Cyril Smith

ISOLATED alloys of copper and silicon were prepared and examined by chemical methods more than one hundred years ago, but it was not until the work of Rudolfi1 that the equilibrium relations. were studied. The early history of the alloys was well described by Baraduc-Muller2 PERCENT SILICON-BY WEIGHT FIG. 1.-COPPER-SILICON EQUILIBRIUM DIAGRAM ACCORDING TO RUDOLFI (1907). and need not be further discussed here. The diagram of Rudolfi, based entirely on thermal observations, showed silicon to be soluble in copper up to 4.5 per cent. at 849° C., at which temperature there was a peritectic horizontal resulting from the formation of a 0 phase with about 7.4 per cent. silicon from a and liquid with 7.85 per cent. silicon. The ß phase was believed to form a eutectic with Cu3Si at 820° C. and 9.8 per

Jan 1, 1928

By F. S. Crawford

IRON and copper are mined in the Lake Superior district. The iron mines of the district have the best safety record for that industry in the country as a whole, while the copper mines of the district rank second in two of the four years recorded (Table 1). In Utah copper comes mainly from open-pit mines, which enables that state to lead easily in safety. All of the Michigan production comes from deep underground workings. About 60 per cent of the iron miners in St. Louis County, Minnesota, are employed at open-pit mines; this favorably affects the combined open-pit and underground accident-frequency rate, as this county provides most of the Minnesota-mined iron ore. In Michigan, however, there are few open-pit mines, the bulk of the production coming from underground mines, while all of the Wisconsin production, just across the state line from Michigan, is from underground mines. In spite of the fact that fewer mines in Michigan use the safer open-pit method, the iron-mining industry of that state maintained a consistently low record from 1931 to 1934; however, it was many points behind its nearest competitor, Minnesota, with its much greater production from open-pit mines.

Jan 1, 1939

By J. F. Stiehr, R. L. Sanford, T. L. Myers

This paper summarizes the development of a Directory of Computer Programs Applicable to US Mining Practices and Problems. The directory is funded by the US Bureau of Mines and includes a sampling of computer usage in operating and manufacturing companies, consulting firms, computer companies, research organizations, universities, and various US government agencies. General references to computer applications throughout the mining industry are discussed as well as the availability of programs to interested organizations or individuals.

Jan 9, 1979

THE education of adolescents to perform the duties and assume the responsibilities of maturity has been a characteristic of human society since the dawn of history. In the beginning the members of the immediate family performed this function, and in modern life they still have an important part in it. Possibly religion was the first field in which education began to be functional; young people were sent for instruction to a teacher who had a broader and deeper knowledge of the subject than was possessed by the family. It does not seem necessary for our purpose to attempt to determine how, when, or where instruction in the practical arts first began to become functional, and the brief outline which follows must suffice. The discovery and utilization of mineral substances to improve and maintain the conditions of human living is a practical art, which must have had an almost accidental origin and have been developed by empirical experiments. We do not know, nor would it be useful to try to fancy, how men first learned that they could make use of mineral substances to their benefit, but however that knowledge was initially gained it was certainly trans- mitted through instruction in the family. At fist such activities must have been merely a minor part of the making of a living, bit in time those who excelled found it better to devote them-

Jan 1, 1941

By J. W. Rutter, K. T. Aust

The temperature dependence of the rate of grain boundary migration was measured in bicrystals of zone-refined lead containing from 20 to less than 1 ppm by wezght of tin. The apparent activation energy in the temperature range from 320" to 200oC is markedly dependent upon the solute tin concentration and upon the orientation relationship of the grains adjacent to the grain boundavy. The quantitative experimental observat~ons are compared with the predictions of various theories of grain boundary migration. In previous work.&apos;?&apos; the mobility of individual grain boundaries was studied as a function of impurity concentration and type of boundary. Grain boundary migration occurred at the expense of dislocation arrays which were introduced into the specimen during solidification. Boundary mobility in zone-refined lead at 300°C was markedly decreased by small additions of tin. 0.004 wt pct being sufficient to decrease the rate of grain boundary migration by a factor of 1000. The mobility of grain boundaries having polar orientation relationships near 38 and 22 deg about <Ill>, and 28 deg about <100>, was much less sensitive to tin concentration in the range studied. As a result, these boundaries have relatively high mobilities. The present paper is a continuation of the above study. Data are now presented on the temperature dependence of the motion of individual grain boundaries in zone-refined lead as a function of solute tin concentration and orientation relationship of adjacent grains at the grain boundary. The experimental observations are compared with the predictions of a number of theories of grain boundary migration3-8 which, prior to the present experimental investigation, could not be critically evaluated. EXPERIMENTAL PROCEDURE The striation or lineage structure of melt-grown single crystals of zone-refined lead, containing various additions of tin, was utilized to provide a driving force for grain boundary migration, as previously described.1,2 Each grain boundary under study separated the striated single crystal from another grain which was introduced by localized plastic deformation and recrystallization of a small region of the sample. The speed of migration of grain boundaries in dilute alloys of tin in zone-refined lead was investigated as a function of 1) tin concentration from < 0.0001 to 0.002 wt pct, 2) temperature in the range of 200" to 320°C, and 3) orientation relationship of the adjacent grains at the grain boundary. The substructure driving energy available for grain boundary migration was estimated to be about 4000 ergs per cu cm, within a factor of two, from specimen to specimen.&apos; The specimen dimensions, and growth and alloying procedures for the preparation of striated single crystals of lead of known tin composition, were as described previously.&apos; Each bicrystal was carefully wrapped in aluminum foil, and annealed in a well-stirred salt bath consisting of 50 pct NaNO2 and 50 pct KNO3, for known periods of time at a series of constant temperatures (*2°C). The grain boundary positions, before and after each anneal, were determined by etching lightly in a solution of 5 pct nitric acid in methyl alcohol, in order to follow the motion of the boundary and determine its rate of migration. Thus, the rate of motion of the grain boundary in a single specimen was measured at various temperatures. The above procedure was carried out for each grain boundary in seventeen different bicrystal specimens.

Jan 1, 1960