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By C. V. O. Hughes

Florida phosphate operations are unique in the ways standard mining equipment is made to meet specialized problems. Hydraulic mining and transportation has evolved in meeting three such special problems: 1) surface mining of a shallow, poorly consolidated but wet material; 2) high pro¬duction rates, necessary because of low prices for phosphate rock in a highly competitive market; and 3) preparation of the value-bearing rock, or matrix, for washing and flotation. The magnitude of the problems is better appreciated if the reader understands the size of operations in the area. The Florida phosphate field produces and ships about 10 million tons per year of phosphate rock. All of this has to be concentrated to its shipping grade, either by scrubbing and screening or by flotation.

Jan 1, 1956

By Eugene S. Perry

The oil and gas industries in Montana continued through the year of 1937 with but little change. No new fields were discovered, and production of old fields did not vary greatly. No outstanding wildcat wells were drilled. Perhaps most notable were extensions in the western part of the Kevin-Sunburst field. Acid treatment of wells in the Kevin and Pondera fields continued with gratifying results.

Jan 1, 1938

By William Loblowitz

A simplified system of flotation testing has been developed recently at the Bureau of Mineral Research of Rutgers University. The technique involves the known principle of skin flotation and can be used with minute quantities of sample and reagents in a beaker. A vessel containing the conditioned sample with added water and flotation reagents is held inclined and rotated slowly. Water-repellent particles come in contact with air and float on the surface of the liquid, while wettable particles are submerged. The float is poured off and filtered whereas the nonfloat remains in the beaker. The filtrate may be returned to repeat the process. This procedure can be made quantitative. Separations are obtained and are remarkably complete and repeatable. The effect of different reagents, optimum quantities, pH and other variables can be determined in a fraction of the time required for conventional testing. However, the method gives no information on the effect of frothers and the quality of froth to be expected in a cell, and it is not practical for particles finer than 200-mesh. Unlike other preliminary tests, separate float and nonfloat products are obtained, and their contents can be determined quantitatively by chemical analysis or grain counts. After the optimum reagent combination has been determined, the effect of fines and frothing may be verified in the conventional flotation cell. On the other hand, agglomeration-tabling can be directly duplicated from beaker tests. Procedure: Five to ten grams of sample are weighed into a 100-ml beaker. Flotation reagents and a small initial quantity of water are stirred together; additional water is then added to produce the proper water-solids ratio. The beaker is then tilted to 45" and rotated slowly. After three to five rotations, liquid and float are poured off and filtered; the filtrate may be recycled until the separation is completed. One test generally requires less than 10 min. Reagent concentration and pH remain quite constant because of the recycling of the filtrate. Two to four tests may be made simultaneously, and the effect of varied conditions may be observed by comparison. Considerable time is saved in preparation and handling since small quantities of sample suffice for a series of systematic tests. Repeatability One test was repeated four times under constant conditions. The sample used was a quartz sand containing approximately 24 pct feldspar and some clay aggregates. The +28-mesh grains had been screened out, and most of those finer than 100-mesh had been removed by hydraulic classification. The results are presented in Table I. For comparison, 500 g of the sample were separated by agglomeration-tabling using the same reagent combination and quantities as given in Table I. The weight percent float was 18.3 pct, composed almost entirely of feldspar and with only traces of quartz. Most of the remaining feldspar was recovered in a middling product with 2.2 pct by weight.

Jan 1, 1952

By Richard R. Klimpel

The role of dispersion is described in the wet grinding of ores using tumbling media mills and the flotation of coal, sulfide, and non-sulfide ores. Emphasis is placed on characterizing the effects of dispersion in laboratory tests using engineering models which provide information useful for the improvement and control of existing plant operations. Significant economic gains in the above named operations have been realized using these models as guides for full- scale plant testing.

Jan 1, 1980

By William P. Blake

The importance to the growing steel industry of the United States of a domestic supply of ferro-manganese or "spiegel" of a high grade, induces me to bring to your notice some details of the method by which a superior article is produced in the Austro-Hungarian Empire. At Reschitza, Hungary, and probably at Laibach also (the Krainische Industrie Gesellschaft), ferro-manganese is made in a blastfurnace, with charcoal as fuel, and limestone as the flux. The ore is a ferruginous mixture, containing about 37 per cent. of sesquioxide of manganese. It is silicious, and somewhat, resembles, in its appearance, the manganese ore from Red Island, in the Bay of San Francisco, California. It contains about 29 per cent. of silica and some alumina, shown by the subjoined analysis:

By D. G. Mickle, H. L. Hartman

Hydraulic filling was probably first used as a means of ground support in 1864 in an anthracite mine at Shenandoah, Pa. In the nearly 100 years since that time it has gained widespread acceptance, but surprisingly little study has been made of the basic features of the process. The investigations that have been made primarily concern the design of preparation processes and transportation systems, while little attention has been paid to ensuring that the fill does its job adequately after placement. Both permeability and compressibility of fills have been studied in the laboratories of the Department of Mining at The Pennsylvania State University under the sponsorship of the Mineral Conservation Section, formed to promote efficient utilization of the state's resources. Results of these studies form the basis of this article.

Jan 11, 1961

By R. Dawson Hall

Discussion of the paper of R. DAWSON HALL, presented at the San Francisco meeting, September, 1915, and at the New York meeting, February, 1916, and printed in Bulletin No. 105, September, 1915, pp. 2013 to 2021. R. DAWSON HALL, New York, N. Y.-The general practice in the past has been to view the roof as being somewhat subject only to shear. In fact the action of the roof under the stress of its own weight has been but little considered, not because the matter is unimportant but because it is so complicated that it has been felt that an analysis of it would not result in any conclusions definite enough to justify the inquiry. The result has been that the consideration of the subject has fallen into the hands of persons who are not experts in the study of beam and plate stress. They have been disposed naturally to view the destruction of the roof as the outcome of the simplest of stresses-vertical shear. In the lack of a careful consideration of the conditions of roof fracture it was thought that the roof consisted of a number of horizontal layers, which were each of them weak, because, no matter how strong they might be they usually lacked sufficient depth. This view of the condition of the roof would naturally lead one to expect that it would yield to bending moment, the various layers succumbing one by one to their lack of the necessary radius of gyration to meet such severe stresses. But,

Jan 5, 1916

By H. E. Kramm

During the summer of 1910, I had the opportunity to study in detail the geological conditions of what is known in northern California as " Harrison gulch," in Shasta county. Though the district, as a whole, that is, the western part of Shasta and the eastern part of Trinity county, has contributed during the last 15 years a considerable share of the gold-production credited to Shasta county, very little is known of its geology, perhaps because the country is covered with a dense growth of brush which makes exploration and prospecting extremely difficult. Topographically the district presents a succession of ridges trending approximately N-S., and alternating with deep, narrow canyons. The drainage is partly into the Sacramento, partly into the Trinity river. Climatic conditions in summer time are almost ideal. It is true, the thermometer may climb to 115°, but the air is dry

Jan 1, 1913

By Herbert A. Everest

The idea of economical production is usually associated with large operations, tonnages, and mines, with even larger capital behind them. , Nevertheless many small mines operate in the shadow of large competitors and make a good showing on the capital invested despite larger overhead expenses. For the purpose of this discussion I will divide the cost of production into classes, and specify opposite each the approximate percentagc expended thereon: 1. Labor, including miners and company men; 60 to 75 per cent. 2. Development, including all necessary .yardage, room turning, crosscuts, etc.; 7 to 12 per cent. 3. Deadwork, covering payment to miners for handling falls, draw-slate, or faults, rock work, water, and in general, all nonproductive labor; 3 to 7 per cent. 4. Supplies: mine timbers, oil, brattice material, lumber, cement, and repairs to equipment; 2 to 6 per cent. 5. Expense: management, selling, office, taxes, etc.; 1 to 5 per cent. 6. Depreciation of coal reserves and royalties; 6 to 10 per cent. 7. Depreciation of equipment and interest on capital invested; 1 to 3 per cent. 8. Fuel; ½ to 1½ per cent. The labor cost for a small mine is relatively much lower than for a large mine, particularly the sum paid to company men. Idle-pay expense is cut to a minimum; the labor item being larger than all the others together, a saving in labor makes a decided showing on the total cost. The development charges in small and large mines are about the same. There should be a small showing on the deadwork item in favor of the small mine. The unit cost for supplies is usually small in the small mine. The operator of the small mine finds, owing to a limited tonnage, that the expenses of management, selling, etc., are abnormally high. The item, depreciation of coal reserves and royalties, is usually about

Jan 1, 1916

By John F. Abel

Personal gain seems to be the most powerful incentive to economic progress. One of my first exposures to this phenomenon was the comparison between company stopes and leaser's stopes in a vein gold mine. The company stopes were 4 to 6 ft wide, whereas the leaser's stopes were so narrow that in some places one could not turn around. The company leased only that ground it felt was marginal to mine with day's- pay miners, but by skillful, careful and energetic mining, the leasers managed in most cases to make money for themselves and the company. The Hurting Truth This capitalist system, which puts a premium on successful risk taking, is under attack. Not that it hasn't been under attack all along. What hurts and angers us at this time is that the attack comes from the children of the system-its youth. Such blasphemy should, of course, be eradicated, root and branch. Or should it? Are we hurt in part because some of the things they say are true?

Jan 1, 1970

By Frank C. Roe

Two cogent and ubiquitous facts have supported a constant search by the ore processing industry for better wear resistant materials in equipment. First, designs and types of equipment change or improve continually to meet the economic and physical demands of different and/or leaner ores. Second, practically all equipment is subject to impact and abrasion conditions that probably are more severe and extensive than in any other industry. Development and testing by operators and equipment manufacturers alike, has produced an extensive variety of longer lasting metal alloys, rubber, plastics, ceramics and other materials to improve equipment performance under different specific conditions. The need for diversified materials becomes obvious upon the simple realization that no two beneficiation operations are identical. Among the variables in the handling of ore are: 1. Size and weight of ore particles. 2. Hardness and sharpness of ore particles. 3. Concentration of ore particles in liquid or gas suspension. 4. Velocity and direction of particle impact toward equipment surface. 5. Coefficient of friction between ore particles and equipment surface. 6. Temperature of operation. 7. Chemical environment of operation.

Jan 12, 1967

By Ed L. Reed

INTRODUCTION The most efficient development of a mine plan for in-situ leach (solution) mining must be based upon an understanding and application of the basic hydrologic characteristics of the aquifer containing the mineral values. Similar knowledge of the overlying and underlying aquifers is also required. This paper summarizes the hydrologic properties of a ground water system and describes some of the more important conclusions that can be drawn from a detailed hydrologic study. Basic to an in-situ leach mining operation is the flow of fluids through porous rock from place to place. The degree to which these movements of fluids can be predicted and controlled determines to a large extent the efficiency of the ore recovery operation. HYDROLOGIC CHARACTERISTICS The principal hydrologic characteristics of a porous medium (sand, intercrystalline or vuggy limestone, fractured basalt, etc.) influencing fluid flow are: Porosity Permeability Thickness Transmissivity Storage Coefficient Water Table or Piezometric Surface Hydraulic Gradient Briefly these parameters can be defined as follows: Porosity: the void space in a unit volume of rock. Permeability: the ease with which fluid will flow through a porous medium. Thickness: the height of the formation which contributes flow to a well. Transmissivity the product of permeability and thickness. Storage Coefficient. the volume of water released from the reservoir per unit drop in head. Water Table or Piezometric Surface: the level at which water will stand in a well: the top of the zone of saturation in a gravity aquifer; the height to which water will rise above the confining bed in an artesian system. Hydraulic Gradient the direction and rate of dip of the water table or piezometric surface. A properly designed pumping test will provide numbers for transmissivity, storage coefficient and the water table or piezometric surface. Drilling records or bore hole logs provide aquifer thickness data from which permeability can be calculated. Ground elevations applied to measured depths to water enable one to calculate the direction and rate of dip of the water table or piezometric surface. Porosity can be determined from core analyses or density logs; it can be estimated from grain size distribution curves in sands or sandstones and from, microscopic examination of drill cuttings derived from carbonate aquifers. CHARACTERISTICS OF FLUID FLOW The characteristics of fluid flow that are vital to an understanding of leach mining include: Velocity Direction Flow Path Radius of Influence The velocity of fluid flow is of paramount importance in planning and managing a leach mine operation. Velocity is directly proportional to the permeability and hydraulic gradient and indirectly proportional to the effective porosity The permeability determined from a pumping test is an average value for the interval stressed; therefore, the velocity calculated from data derived from a pumping test represents average conditions. Under actual conditions discrete portions of the aquifer open to the screen may have permeabilities several times as high as the average and minimum permeabilities only a fraction as much. An injection front will be irregular to the extent that the reservoir rocks are heterogeneous An important consideration is the direct relationship of velocity to head. A reservoir which would provide a velocity of 0.05 feet per day under conditions of equilibrium would allow fluid flow of 36 feet per day under typical leaching operations, i.e. 12-foot injection head, 12-foot pumping level and 50 foot five-spot pattern. The direction of fluid flow is also vital both inside and outside the mine area. In the pattern area the direction of flow is determined by the geometry of the well field and can be approximated by mathematical modeling techniques. Outside the well field, the direction of flow is influenced by both natural conditions and the degree to which production and injection volumes are balanced. Flow directions (and velocities) are critical to an understanding of leachate excursions and their control.

Jan 1, 1979

By P. C. Keith

IT is difficult to talk about atomic energy and the engineer without repeating a number of phrases that have been worn smooth with use Mr John M. Hancock has spoken to you of the two-sidedness of atomic energy, one useful, and the other destructive. If a control plan of the type that he has outlined is adopted it will be perfectly possible to go ahead with the peacetime development of atomic energy Failing the adoption of such a plan, emphasis will of necessity be placed upon the perfection of atomic energy as a weapon of destruction I want to speak, however, in the hope that atomic energy will be developed for peace-time use, and speak about the role of the engineer Before I can do that I must, outline the framework within which the engineer must work, and then I would like to go back and tell of some of the things that he has done, in the hope that that may throw some light on what he may be expected to do in the future Last year the McMahon Committee the Senate Committee charged with drafting domestic atomic-energy legislation-held extensive hearings in an effort to strike a balance between the negative attitude of what to do about atomic energy and the positive attitude of what to do with it Out of these hearings grew the United States Atomic Energy Act, calling for a civilian commission to exercise control over all atomic-energy activities in this country As you

Jan 1, 1947

By H. E. McCoy, C. J. McHargue

Single crystals of columbium containing various levels of oxygen, nitrogen, carbon, or hydrogen were deformed by slaw compression and impact loading at -196°C. For the slow deformation rates. 1500 to 1900ppm oxygen, 500 pprn nitrogen, or 150 to 200 ppm carbon completely suppressed mechanical twinning. Hydrogen in concentrations to 1000 ppm had no apparent effect on ease of twinning. Impact loading caused twins to form at all levels of contamination studied, and cleavage mucking on (100) planes occurred in specimens having higher interstitial contents. It is well established that, under some conditions, the bcc metals vanadium, columbium, tantalum, chromium, molybdenum, tungsten, and iron deform by formation of mechanical twins. In general it has been accepted that high strain rates, low temperatures, and large grain sizes are conducive to this kind of deformation.' Since interstitial impurity atoms have a relatively large effect on slip in bcc metals, one might sus- pect a similar effect on twinning. This could occur directly by the interstitials affecting the nucleation or growth of the twins or indirectly from their effect on slip. It has often been argued that the large increase in yield stress caused by interstitial elements enables the effective stress to exceed that necessary to cause twinning. The twinning stress has always been thought to be higher than the stress necessary to cause slip in pure metals.2 simonsens and Tipper and Hall4 found profuse twinning in very pure a iron even at room temperature, whereas Low and Fueste15 and Churchman and tottrell' observed twins in a iron containing carbon but none in highly decarburized specimens. McHargue7 reported mechanical twins to form readily in vanadium which contained 390 ppm interstitigs, while Clough and Pavlovic8 found twins only in the one or two grains adjacent to the fracture surface in vanadium which contained 1500 to 1700 ppm interstitials. In columbium, McHargue9 found high-purity single crystals to twin easily whereas Churchman,10 Adams, Roberts, and mallman,11 and Johnson12 studied less pure material and found far fewer twins. Although the results of Leadbetter and Argent13 showed oxygen to inhibit twinning, a study by sheely14 indicated the opposite to be true. Chromium exhibits this mode of deformation15,16 but there are no data regarding impurity effects. Lawley, Van den Sype, and Maddin17 observed twins in very pure molybdenum single crystals deformed at 77°K but none in less pure crystals. The work by Cahn18 and

Jan 1, 1963

To control the slag in an iron blast furnace is to control the quality of the pig iron produced (and to a certain extent the tonnage), and to control the whole operation of the furnace itself, including a large part of the cost of production. The character of the slag is the determining factor in the character of the pig iron as to the controllable limits of sulfur, silicon, and, to a certain extent, the manganese; it has an influence on the proportions of combined and graphitic carbons.

Jan 1, 1935

To control the slag in an iron blast furnace is to control the quality of the pig iron produced (and to a certain extent the tonnage), and to control the whole operation of the furnace itself, including a large part of the cost of production. The character of the slag is the determining factor in the character of the pig iron as to the controllable limits of sulfur, silicon, and, to a certain extent, the manganese; it has an influence on the proportions of combined and graphitic carbons.

Jan 1, 1935

By G. Wranglen

On account of the possibility of isolating carbides in steel it is generally assumed that the electrode potential of iron carbide is more noble than that of ferrite.1,2,3,4,5 Differences from 0.032 V1 to 0.4 V4 have been recorded. However, it is important to realize that the more noble behavior of cementite in relation to ferrite is not an issue of thermodynamics but of reaction kinetics. Theoretically, cementite is less noble than ferrite, which is a direct consequence of its thermo-dynamic instability. With the value ?F°298 = +4700 cal per mol for the free energy of formation of cementite6 it is easily calculated that the electrode

Jan 1, 1950

By G. L. Oldright

DURING 1919, in the face of high cost for labor and supplies and a rapidly dropping copper market, the management of the Ohio Copper Co. of Utah was left with an orebody that had been shown to be very low grade, and a mill that could not make a satisfactory recovery, even by flotation, because a considerable proportion of the copper minerals was oxidized. About seven million tons had been mined by the use of a caving system, the best of the broken ore extracted and milled, and the nature and copper content of the rest of the orebody fairly well determined. The rock of the whole mine was shown to run between 0.3 and 1.3 per cent. in. copper. As, the Ohio Copper orebody lies at the contact of the original sandstone (now altered to quartzite) with the quartz monzonite intru-sion that was the source of the mineralization at Bingham Canon, the rock was thoroughly shattered. It was shown further that the rock was mostly quart-zite, with a few quartz-monzonite "fingers" projecting into it. Although some of the old cleavage planes had been healed by resilicification so as to leave some of the copper minerals disseminated in the rock, a large proportion of these minerals was distributed along the cleavage planes.

Jan 10, 1923

By Alex G. McKenna, Thomas M. Drown

The unsatisfactory character of most, if not all, of the processes for the direct determination of alumina in the presence of iron and phosphoric acid, and the sharpness with which both the iron and phosphoric acid can be determined, have led chemists to rely mainly

Jan 1, 1892

By Calvin C. Brown

A university is a place to build minds and develop leaders. It provides the tools necessary for the development of new ideas which come from the inquisitive mind and is one of the stepping stones to management responsibilities for the truly ambitious. However, it is not always a financially sound investment! Lately, there have been several articles published on the economic advantages of a college education. These articles tend to average wages together according to education and years of service. Their tabulations generally include the chairman of the board, various vice presidents and plant managers and do not reflect the achievement of the average graduate. They consistently fail to include an analysis of the investment a college education requires. In reality, the bright high school graduate would make more real money over a 20-year period if he went directly to work "on the hill" than he would if he graduated from college. Furthermore, he would find little difference between his wages and those of the college graduate in the period from 20-30 years after high school graduation.

Jan 1, 1971