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By F. W. Lee

A GREAT CURTAILMENT of field activities among the geophysicists occurred last year, especially in prospecting for the common metals. In gold, however, an "outstanding achievement . . . was made by the engineers of Consolidated Goldfields. Here the suboutcrop of the Main Reef Series was traced from Middelvlei through properties of the westward area, a distance of from 30 to 40 miles. Here Drs. Reineche and Krahman prospected with the aid of a sensitive magnetometer and established the singularities of the various beds which heretofore had not been sufficiently appreciated. Several underlying shale beds were used to determine this suboutcrop under the dolomite. This area promises to be the equivalent of one-half the size of the present gold fields and to rank in value with the Far East Rand." The present temperature compensated magnetometers permit accurate field observations to less than 5 gammas. Since magnetic anomalies may have their origin due to a change of elevation as well as to the outcropping of a bed of another magnetically different material, intimate geological knowledge is of great assistance in the interpretation of these measurements. To what extent magnetic measurements reflect the basement when the material is homogeneous, consisting primarily of red granite, was determined by members of the Bureau of Mines and described by Dr. J. H. Swartz. Because of the diverse causes of magnetic anomalies, some of which were discussed and correlated by Stratton and Joyce upon known conditions, magnetometer measurements are often difficult to interpret.

Jan 1, 1933

By H. C. Schultz

CERTAIN local conditions were known to govern in large measure the successful adaptation of liquid-oxygen explosives to the large-scale blasting at Chuquicamata. The wide variation in hardness of the rock at this mine makes necessary the use of several types of explosives. A locally manufactured, relatively cheap black powder is used in blasting the softer waste and capping material, where a thorough displacement breaks the ground sufficiently. Before the introduction of L. 0. X., an ammonia dynamite of about 65 per cent. strength was being used exclusively in the harder underlying orebody, where a strong disruptive as well as a displacement effect is required for breaking the ore. The L. 0. X., as developed for quarry work in the United States, has a practically pure carbon cartridge material, and the explosive has an extremely high rate of detonation, which should therefore cause it to usefully develop its full disruptive effect in hard ground. The individual blasts at Chuquicamata are large, black-powder shots which dislodge masses of rock averaging 250,000 tons each, and dynamite shots which dislodge masses averaging 80,000 tons each. It was desirable, therefore, to attempt to displace with L. 0. X. the faster, higher-cost ammonia dynamite used in the smaller blasts. It was not considered practical to attempt to displace the low-cost black powder with L. 0. X., as estimated costs showed no probable saving if this were accomplished. Since it was desirable to continue shooting relatively large blasts for effective operation, it was recognized that larger storage facilities than had been in use would be needed for the liquid oxygen. Because of the difficulty of transporting and discharging large storage containers of efficient design, the better plan appeared to be storage and discharge of the liquid at the place of manufacture, and transportation of the filled soaking boxes to the blast.

Jan 1, 1928

No. 264. A long established company operating steel and iron foundries, machine and forge shops, whose varied products are sold to the Government, railroads, mining and contracting industries, etc., has, openings in both manufacturing and selling departments for men with technical education and experience who are not subject to military call. State full particulars, kind of position preferred and salary expected. No. 265. Young man wanted, technical graduate preferred, to superintend construction f a small charcoal blast furnace. Man with blast-furnace experience preferred. For the right kind of man this is, not only a permanent job but an opportunity. In writing, give full particulars as to age, education, experience, salary wanted, etc. No. 26.6. An important copper mining and smelting company in Arizona needs two or three metallurgical chemists, at salaries. ranging front $150 to $175 per month. No. 267. A consulting mining engineer needs two superintendents for developing chrome deposits near Philadelphia; and another technical man for other engineering work in the same vicinity. No. 268. An iron-mining company, in New York State needs a mining engineer with knowledge of geology and acquaintance with construction work; A married man, with about 10 years' engineering experience preferred.

Jan 2, 1918

By AIME

THE wind howls almost incessantly over the mining engineers working in the near desert that is the Division of Namaqualand, the upper Atlantic coastal corner of South Africa's Cape of Good Hope Province. But when these men at the U. S.-owned mines called Nababeep South and East O'okiep (pronounced Oh-keep) tell you about their achievements, they can be heard above the wind. For their O'okiep Copper Co. Ltd. now produces over half the Union of South Africa's annual output of 30,000 tons of copper metal. Moreover, it is a very decent sample of U. S. geotechnical imagination. financial daring, and managerial skill, all operating successfully in a

Jan 1, 1947

By P. D. Rao, H. B. Charmbury, D. R. Mitchell

As a result of a changing market pattern for anthracite, there is now an increasing demand for steam size and a decreasing demand for domestic sizes. To help the producer meet this new demand, the authors present the technical aspects of the problem of crushing domestic sizes to steam fineness and size. The market pattern for anthracite coal has changed considerably in recent years. The demand for domestic sizes has been gradually decreasing and the demand for the steam sizes has been increasing. The companies however aim for a maximum production of domestic sizes, since these sizes command premium prices. To meet the market demands, particularly in certain periods of the year, further size reduction of the coarse clean coal is necessary. The present practice of multistage crushing in toothed rolls leads to complicated flow arrangements and is high in cost. Data presented herein indicate that crushers with high reduction ratios could be used with a resulting simplification of crushing flows and an appreciable reduction of capital and operating costs. The different types of crushing equipment investigated included the rotary-type breaker, the jaw crusher, the impactor-type crusher, and the Aerofall mill. CURRENT PRACTICE The standard sizes of anthracite are presented in Table I and market specifications require that any given size be maintained with only a limited amount of oversize and undersize material. The 1958 prices of the various sizes also are presented, so it may be seen that size reduction is only performed when dictated by market demands. At the present time the general practice of crushing anthracite consists of removing the top size and crushing it in a toothed double roll crusher to the next largest size. Consequently, to reduce the domestic egg, stove, and nut sizes to steam sizes of pea, buck, rice, and barley, the original material must be screened to produce the three top sizes and each size must be crushed in three separate rolls to the next largest size. Each crushed product must then be rescreened to remove the oversize for re crush ing. Thus a typical operation would consist of scalping the egg size from a mixture, crushing it to stove size, and rescreening the product. This same cycle would be repeated for the stove and nut sizes requiring three screens and three crushers as well as conveying equipment to handle the crushed products. This results in an expensive series of operations to make a product which sells for a lower price. If the three top sizes are crushed in one operation to the smaller sizes then the yield of steam sizes is low and the production of Nos. 4 and 5 sizes is large. These sizes sell for lower prices than the steam sizes. A typical operation is presented in Fig. 1. From the figure it may be seen that the original cleaned anthracite contains 67.4 pet domestic sizes, 26.4 pct steam sizes, and 6.2 pct fines. After multistage crushing of the domestic to steam sizes the composition of the product is 0.6 pct domestic sizes, 89.6 pct steam sizes, and 9.8 pct fines. From a technical standpoint these results are reasonable but the handling and crushing costs are

Jan 1, 1961

By G. L. Schroeder

Investigations were conducted at two underground locations, foreman's room and 5702 area, of the Kermac Nuclear Fuels Corp. uranium mining installation, Ambrosia Lake, New Mexico. The rock environment is stratified sandstone. Pressures were varied from minus 0.4 an Hg to plus 3.8 cm Hg with respect to barometric pressure, and were maintained for periods ranging from several hours to 21 days. One cm Hg overpressure (-1.5% of normal barometric pressure) produced a 20-fold decrease in Rn flux into the foreman's room as compared to the Rn flux observed during dilution ventilation. The 5702 area experienced a 5-fold decrease in Rn flux for a similar overpressure. During 21 days of continuous 1 cm Hg overpressure in the 5702 area this reduced Rn flux was maintained. The smaller reduction in flux for the 5702 area results in part from the proximity of the foreman's room to a non-pressured area and the presence of an impermeable shale lens overlying the ceiling of the 5702 area. A 0.4 cm Hg underpressure of the 5702 area increased the Rn flux into the area by 3-fold over the non-pressured value. A barometric pressure influence on Rn flux into the mine and on air Rn concentrations in non-pressurd areas of the mine was measured. A falling barometric pressure causes an increase in the flux of interstitial gas into the mine; a rising barometric pressure decreases this flux. These effects are not seen in overpressured mine areas. Radon concentrations in rock interstices show, during overpressure, decreases of all locations monitored except in the immediate vicinity of the shale lens above the 5702 area ceiling. These reductions are the result of air flowing from the mine into the rock interstices under the influence of the pressure gradient induced by the overpressure. The relative humidity of the 5702 area was reduced after 2 days of 1 cm Hg overpressure from a pre-overpressure value of 96% to 81%. The control of harmful or noisesome gases which emanate into underground mining areas from surrounding rocks is often a costly necessity. In uranium (U) mines this problem is presented by the high interstitial concentrations of radon-222 (Rn), a radioactive noble gas of 3.82-day half-period, formed in the decay scheme of U238, and the relative ease with which this noble gas diffuses from its parent rock into the interstices of the rock and then to a working area. Long-term exposure to moderate concentrations of Rn (3000 µµc per 1) and its short-lived alpha-ray emitting daughter products, RaA (Po218) and RaC (po214), has been found to result in an increased incidence of bronchial carcinomaa2 The acceptable limit of Rn daughter products in a mine atmosphere is presently set at a concentration of short-lived radon daughters which would be in equilibrium with 100 ppc of Rn per 1 of air. Ventilation of mines is conventionally accomplished by continuously diluting the mine air with fresh air brought in by fan or natural convection from above ground surface. The diluted air is allowed to vent freely to the atmosphere. This process does nothing to retard the rate at which gases (including Rn) diffuse into the mine from surrounding rock. It merely reduces the concentrations of these gases within the mine. It is suggested that in a sufficiently permeable rock environment a slight pressurization of the mine air may induce air flow from the mine into the interstices of rock surrounding the mine. The convective flow of comparatively fresh air will reduce the concentration and the concentration gradient of undesirable gases in the rock interstices adjacent to the mine. Radon will diffuse counter-current to this convective flow at a rate proportional to its concentration gradient. In time, a steady state of convection and counter diffusion will be established. The Rn flux into the mine will never be reduced to zero, and will only asymptotically approach zero as the overpressure (and hence the convective velocity of purging air) approaches infinity. During 1963 and 1964, an investigation into the effect which such applied pressures have upon the Rn characteristics of a mine atmosphere was conducted at the Kermac Nuclear Fuels Corp. uranium mines, Ambrosia Lake (near Grants), New Mexico.

Jan 1, 1967

By George S. Rice

STUDIES of ground movement and subsidence caused by mining necessarily chiefly deal with causes and effects of making extensive excavations underground with spans beyond the strength of the un- supported or temporarily timbered roof or hanging wall. Perhaps no other phase of engineering is so de- pendent for results upon the assemblage of what may be called "experience data." That this is the case is cot surprising when one considers the number of variables involved in any at- tempted mathematical formula to determine the angle of draw or the angle of permanent slope of the rocks in any particular case. It is not like dealing with construction materials in which, through testing of. small specimens, in conjunction with the tests of large built- up specimens, relative stresses and strains may be deter- mined and formulas closely approximated for still larger constructions.

Jan 1, 1931

By J. A. SINGMASTERN

THE New Jersey Zinc Co.'s vertical retort plants are believed to have been in continuous operation through the whole year. At Palmerton metal purer than that made from the same ore in the old plant has been produced and has been able to compete successfully with very pure electrolytic metal in die castings and other special uses where extreme purity is worth money. A new plant using this process was put in production by the Grasselli Chemical Co. at Meadowbrook, W. Va., early in the summer. It is said to be working very satisfactorily. It is understood that this plant will not produce high-grade metal. Two patents issued to Bunce and Mahler (Nos. 1,749,126 and 1,749,127) describe a method of operating the vertical retort so that practically lead-free metal can be obtained from ores containing consider- able lead. The zinc vapors and other gases leaving the reaction zone are filtered through a column of material maintained at a temperature high enough to prevent much zinc from condensing. The filtering medium is either periodically or continuously changed.

Jan 1, 1931

By Eckley B. Coxe

The subject of this paper will be treated as briefly as possible under the following heads : I. The latest designs of some of the machinery used at these collieries in the preparation of coal. 11. The means employed for elevating, conveying and transporting the coal and slate in and about the breaker. 111. The means employed for raising the coal from the mines to the top of the breaker. IV. The iron breaker as a structure. V. The preparation of the coal as effected in the iron breaker. A key to the plates and the letters and numbers designating different parts, will be found at the end of the paper. I. Preparing Coal. Anthracite coal as it comes from the mines is not marketable. The "run of mine" cannot, as in the case of bituminous coal, be sold. Anthracite, being very compact and practically free from volatile combustible matter, burns only at the surface, and it is, therefore, deemed important to have the lumps as nearly of a uniform size as possible, so that between them a large amount of surface will remain exposed to the action of the air without checking the draught too much, or allowing enough air to pass to cool the coal below the ignition-point, In other words, if the pieces of coal of the size of a chestnut and smaller are mixed with lumps of the size of an egg they fill the air-passages and prevent a free draught. It has long been recognized, therefore, that one of the most important points in preparation is to have a uniform sizing, and also to make as large a number of different sizes as can be produced without too

Jan 1, 1891

By B. D. Saklatwalla

FOR the proper understanding of the inclusion of certain elements in this review it seems necessary to state the meaning of "rare metals." Certain elements occur in deposits limited in extent or concentration, so that the extraction of the element in relation to market conditions becomes uneconomical. Others may occur in extensive and rich deposits but the reduction of the metal may be difficult and costly. Both these conditions effect the same result, namely, make the metal rare and costly. As an example of the first kind may be mentioned radium and of the second, calcium.

Jan 1, 1939

By Nagel, Theodore

USE of oxygen in metallurgical operations was investigated by a committee of unusually able engineers more than ten years ago. A record of their work appeared under the title "The Use of Oxygen or Oxygenated Air in Metallurgical and Allied Processes," Serial 2502, Report of Investigations, U. S. Bureau of Mines. Shortly thereafter the A.I.M.E. published "Use of Oxygenated Air in Metallurgical Operations," based on a symposium at the New York meeting, February 1, 924. Quoting from the Bureau of Mines report In view of the many recent developments in oxygen manufacture, and considering the increasing cost and decreasing quality of our raw materials, the Bureau of Mines has taken the matter of the application of oxygen or oxygenated air to the metallurgical centers for consideration and has appointed an advisory committee to study the problem.

Jan 1, 1935

By AIME AIME

BUFFALO, Queen City of the Lakes, singularly accessible by land, water and air, will be the mecca for metallurgists throughout the United States and Canada during the week of the National Metal Congress, Oct. 3 to 7. Headquarters during the National Metal Congress will be the Hotel Statler and there on Wednesday and Thursday, Oct. 5 and 6, the Institute of Metals and Iron and Steel Divisions, A.I.M.E., will hold a series of technical sessions, the annual Science Lecture, a dinner and executive committee meetings. The American Society for Steel Treating, American Welding Society, Production Division of the Society of Automotive Engineers, the Iron and Steel and Machine Shop Practice Divisions of the American Society of Mechanical Engineers, the Wire Association and the American Drop Forging Institute will present a carefully planned program extending throughout the week.\

Jan 1, 1932

Jan 1, 1947

Jan 1, 1947

CONTENTS PAGE Rae, Colin C.-A Possible Origin of Oil. Discussed by S. Linker, Colin C. Rae... 2 Cottingham, Kenneth.-Subsurface Conditions on Portion of Arches Fork Anticline. Discussed by David B. Reger 6 Moyer, W. Irwin.-Time to Pay Out as a Basis for Valuation of Oil Properties. Discussed by H. J. Smith 9 Pogue, Joseph E.-Future Demands on Oil Industry of United States. Discussed by James O. Lewis 11 J. J. Walsh.-Coa-lmine Ventilation. Discussed by W. B. Daly, J. J. Walsh, R. R. Sayers, H. H. Stock, George S. Rice, James W. Paul, D. Harrington, T. D. Thomas 15 Longyear, Robert Davis.-Diamond-drill Sampling Methods. Discussed by Ira B. Joralemon, J. J. Rutledge, E. C. Harder 19 Joralemon, Ira B.-Sampling and Estimating Disseminated Copper Deposits. Discussed by J. Parke Channing, John E. Hodge, E.E. Hunner, B. B. Gottsberger, W. Y. Westervelt, W. O. Hotchkiss 20 Boericke, W. F.-Sampling and Estimating Zinc and Lead Orebodies in Mississippi Valley. Discussed by J. Parke Channing, Arthur Thacher 24 Daly, W. B. and Linforth, F. A.-Organization of Mine Sampling at Anaconda. Discussed by George A. Packard, W. B. Daly, B. B. Gottsberger 25 Norris, E. M. and Rahilly, H. J.-Mine Fires. Discussed by R. Dawson Hall, W. B. Daly, Frank Haas, D. Harrington, Robert E. Tally 26 Raymond, R. M.-Safety Practice for Hoisting Ropes. Discussed by B. F. Tillson, Graham Bright, Rudolph Kudlich, J. F. Howe, Robert Peele, H. G. Davis. 30 Howe, J. F.-Use of Wire Rope in Mining Operations. Discussed by Horace F. Lunt, J. F. Howe, B. F. Tillson 36 Tanner, W. N., and Jaccard, F. C.-Wire Rope and Safety in Hoisting at Butte Mines. Discussed by Horace F. Lunt, W. B. Daly, C. L. Colburn, William Kelly, Robert Peele, B. F. Tillson, Graham Bright, Charles E. Locke 38 Richardson, A. S.-Ventilation of Butte Mines of Anaconda Copper Mining Co. Discussed by D. Harrington, Chas. A. Mitke 42 Stuart, Charles E.-Storage-battery Locomotive as Applied to Mine Haulage. Discussed by Howard N. Eavenson, Charles E. Stuart, William Kelly, Arthur Thacher, W. H. Patton, Graham Bright 45 Woodward, C. D.-Electric Haulage Systems in Butte Mines. Discussed by William Kelly, Graham Bright, Howard N. Eavenson, C. E. Arnold, Gerard B. Rosenblatt, K. A. Pauly 47 Harrington, D.-Efficient Ventilation of Metal Mines. Discussed by R. E. Simpson 52 Otagawa, Masayuki.-Mining Methods at the Ashio Copper Mine. Discussed by Horace V. Winchell, D. W. Brunton 52 Stoek, H. H. and Clagett, Thomas H.-Coal Mining Methods. Discussed by P. D. Browning, G. L. Cox, Erskine Ramsay, Frank Haas, George S. Rice.

Jan 6, 1922

By J. A. Fellows, Earnshaw Cook, H. S. Avery

THE increased use of heat-resistant alloys (26 per cent Cr, 12 per cent Ni; 16 per cent Cr, 35 per cent Ni; 12 per cent Cr, 60 per cent Ni; etc.) in recent years has been accompanied by continued demands by the consumer for improvement in properties. The manufacturers of these materials, of necessity, have resorted to more critical studies of the basic causes of variations in fundamental properties. To keep pace with the need for augmented information, previous techniques of investigation have been refined and new test methods and instruments created. It is the purpose of this paper to describe the apparatus, experimental technique and precision of measurement that were employed in the exploration of properties of heat-resistant alloy presented in a companion paper.? The detailed precautions in experimental procedure essential for attainment of accurate and comparable data at elevated temperatures cannot be too highly emphasized. THE CREEP TEST Since the fundamental concepts of creep testing have been recognized for the past 20 years, present interest is restricted to refinements in equipment and experimental procedure. The creep-test laboratory constructed for the American Brake Shoe and Foundry Co. is designed to permit 1000-hr. tests in the temperature range of 1200° to 2200°F. with a choice of applied stress extending from 50 to 50,000 lb. per sq. in. in increments of 50 lb. per sq. in. To simplify the calculation of weight combinations, the loading beams (Fig. I) are provided with counterweights to eliminate the tare. The precision of the knife-edges (10.1 ratio) is such that a 10-gram weight placed on the upper specimen grip will be exactly balanced by a 1-gram weight attached to the loading shackle. Check of the loading weights proved the maximum error to be 0.06 per cent. Axial alignment is provided by crossed knife-edges in the grip seats. The furnaces are similar in design to those of Crane and Company, Battelle Memorial Institute, and the U.S. Steel Corporation. An 80 per cent Pt, 20 per cent Rh No. 19 B. and S. gauge wire is used as the heating element. The details of construction are shown in the radiograph reproduced in Fig. 2. The windings are held in place on an alundum tube with alundum cement; the distribution of turns is adjusted to give a maximum temperature gradient of ± 1°F. over a 4-in. gauge length (Fig. 3). To avoid sharp temperature differentials at the ends of the test section, the length of the furnace is four times the gauge length. Sixteen-inch coupons are used to reduce the temperature of the threaded

Jan 1, 1942

By Lord Marley

ACTIVE participation by the United States in the war acted as a stimulant on the Annual Institute Meeting in New York rather than a retardant as feared. Attendance was about 10 per cent under the all-time high reached last year, but considering the number of men who could not possibly come because of active military service and the additional number who are devoting their whole time and effort to turning out vital war materials, the registration was really greater than might have been expected. But all in all the Institute put on a show that taxed the capacity of the Engineering Societies Building as well as the capacity of the visitors to find time to attend everything that promised to be of interest.

Jan 1, 1942

US 4,190,436 - In the cyanide leaching of gold ore in tailing or ore dump piles, or gold ore in vats or on pads, the ore is agitated and oxygenated by introducing timed bursts of air, along with cyanide in a cyclic or regulated manner. The leach liquor is drained from the material by providing a continuous flow of air. Fines are homogenously mixed, thereby reducing channelling In the ore bed. Yield is improved and cyanide consumption lessened. R M. Hughes Feb. 26, 1980. 7 pp. (75-105). Filed. 12-20-77 (862,335).

Jan 1, 1982

By N. M. Raju, B. Singh

The paper seeks to present the results of experimentation in room and pillar stopes with different ground conditions to determine the safe working span. In the experimental stopes, ground movement was monitored with gradual widening of the room span. The field measurements included closure between the stope walls and the extent of ground movement in the hangwall using borehole extensometers. hock bolting was used as an exclusive support system which enabled introduction of scrapers for improving productivity. In one nine, phosphate bed, 3 to 3.5 m thick dipping at 45O and overlaid by weak laminated shale, was worked at shallow depth of cover. h the experimental panel, five s topes were worked with spans varying from 5.5 to 7 m. In the second mine, the chalcopyrite orebody up to 6 m in thickness dipping at 25 - 30" was worked at a depth of 1100 m. The hangwall consisted of fairly competent schistose rocks and therefore 10 to 15 m wide spans could be experimented. The field measurements confirmed that in the phosphate mine with weak shale roof, 7 m span could be safely worked with subsequent caving of the bolted roof. In the copper mine, 15 m span could be worked and the stopes required subsequent backfilling for better ground control.

Jan 1, 1983

By AIME AIME

WEDNESDAY night, by long tradition, is al- ways set aside for the annual dinner, even when, as it was this year, it is Ash Wednesday. Whether the somewhat smaller attendance than last year is attributable to that cause, the unexpectedly long persistence of business depression, or whatever may have been the reason, it was a joyous occasion, and the grand ball-room of the Commodore Hotel was as completely filled With diners as * was consistent with com- fort. In the half hour before the dinner was actually served the guests assembled in an adjoining room and not only exchanged greetings but proceeded along the receiving line to greet the guests of honor. The number present was so large that hardly more than half of them had been able to do this before the summons to the dining room sounded and a hearty and immediate response was made to it. Toy balloons at each plate, inflated and directed at the heads of companions or nearby friends, but which were just as likely to carom from the nose of a hurrying waiter, successfully broke the ice as well as not a few plates. It would be interesting to know whether the pleasure the guests derive from these de- vices is in part based on the all-too evident annoyance of the waiters, and what the relative quantitative relationships are.

Jan 1, 1931