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By J. D. Mooney, D. L. Darnell

The accompanying chart has been drawn for the convenicncc of engineers as' a means of quickly determining the correct number of plies of conveyor belts operating under specific conditions. The calculations are based on the average safe strength (factor of safety, 15) of the various standard rubber conveyor belts. The calculations assume maximum loading conditions; that is, the belt is considered as carrying the greatest load that it will handle without spillage at ordinary belt speeds. This not only produces the most economical operating conditions, but also the maximum tension in the belt. The chart is a graphical representation of the formula: Where, p = kg W(L + 10H) p = the correct number of plies k = a constant, depending on the type of drive g = the weight 'in pounds per cubic foot of material handled W = the width of the belt in inches L = the length of the belt in feet (approximately twice the center distance). H = the difference in elevation between the head and tail pulleys, in feet. For a simple drive, with a bare pulley, k = ----1 For a simple drive, with a rubber-lagged pulley, k = --- 1 For a, tandem drivej with bare pulleys, k = 1/375.000 For a tandem drive, with rubber-lagged pulleys, k = ---1 The chart is drawn for a simple drive, with a bare pulley (k — =e)1 ; therefore, the number of plies obtained from the chart should be multi- ' plied by the factor 0.83 or 5/6 for simple, lagged drive; the factor 0.67 or 2/3 for tandem, bare; and the factor 0.55 or 11/20, for tandem, lagged. The formula p = kgW(L + 10H) has been developed mathematically

Jan 1, 1916

By Carls Benedicks

It is well known by every one who has had to deal with boiler tubes that these are often seriously affected by a sort of corrosion, occurring as a local pitting, that frequently causes a perforation of the tube in a rather short time. The characteristic appearance of this corrosion is shown in Fig. 1. A very similar corrosion occurs in condenser tubes (Fig. 2).l A study of the microstructure or local chemical composition of the metal (iron 70:30 brass) fails to reveal any cause for this pitting. Of course one might possibly assume the starting point to be some oxide particle, causing an electrolytic local action, but this in no way explains the continued corrosion, progressing even when the assumed oxide particle must have disappeared. By the excellent work done by the Corrosion Research Committee of the Institute of Metals, and communicated, in October, 1923, to the Institution of Engineers and Shipbuilders in Newcastle-on-tyne, stress was laid on the faot that a content of entangled air has a very obnoxious effect. In the following correspondence, Sir George Goodwin stated that "engineers have, for a long time past, regarded air as the big enemy to be fought against in all questions of corrosion'72 and Kenneth Fraser pointed out that the most vital point is "the avoidance or removal of possibly the chief cause of present day corrosion, i. e. entrapped air and gases brought out of solution."3 In their reply, however, the authors state that they had "never for a moment believed that entangled air was responsible for the beginnings of corrosion, and express the opinion that the gradual liberation of air could not account for localized corro~ion."~ On consulting the many textbooks on corrosion, as that

Jan 1, 1925

By S. Arthur Krom

ThE James diagonal-plane slimer is specially adapted to handle the finest slimes, but it will also handle sands as coarse as 40-mesh. The saving efficiency of this machine is due to the original construction ,of the deck, and to the rapid reciprocating movement imparted to it by the head-motion. The deck consists of a plurality of connected planes, having a certain fixed ratio of inclination one to another. These planes intersect each other diagonally to the stroke-line of the table and are arranged so as to give the pulp on the table a double treatment. This double concentration performed by the diagonal-plane deck produces cleaner concentrates and tailings than those obtained by the operation of two separate machines. The action of the diagonal planes settles, combines, and holds all the concentrates in one compact mass, sharply defined from the gangue, and easily cut away without loss. Many slime-concentrating machines distribute the feed-pulp for a distance of 4 or 5 ft. only, and upon a very limited settling-surface. This results in a thick, heavy deposit, from which it is impossible to stratify the values and wash away the gangue, the resulting products being dirty concentrates, and tailings carrying high values. The diagonal-plane slimer distributes the feed-pulp for a distance of 10 ft., and upon a settling-surface having an area of 40 sq. ft.; in other words, it spreads the pulp thinly on the table, which allows the metallic values to settle through the gangue quickly, forming a bottom stratum from which the thinly-distributed overlying stratum of gangue is easily brushed away by the feed-water without disturbing the underlying concentrates. Referring to Fig. 1, plane A is the main settling-section of the table. The feed pulp flows gently down this plane and is

Jan 1, 1913

By Orson Cutler Shepard, Charles F. Skinner

THE leaching method that was first widely used with the cyanide process consisted of percolation leaching of crushed ore in vats or leaching tanks. It was frequently necessary to separate the sand for cyanide treatment and discard the slimes, because only granular material allows the necessary amount of solution to percolate through it in a reasonable time. Later a slime process consisting of agitation followed by thickening and filtration was developed, and is extensively used to the present day. Even though the agitation-leaching slime process is considered satisfactory, the cost of plant and of operation are both greater than for a percolation-leaching plant of equal capacity. This situation has been recognized in the hydrometallurgical treatment of copper-bearing slimes; and a considerable amount of work has been done at the Southwest Experiment Station of the U. S. Bureau of Mines in an effort to develop a percolation method of treating slimes. Experimental work on the copper-leaching problem was started by H. E. Keyes1, and later tests were made by J. D. Sullivan and A. P. Towne2. The Bureau of Mines work resulted in the development of a process by which slimes were moisture-agglomerated with sand and crushed ore, to form a permeable mass through which solution could be trickled without breaking down the glomerules. The agglomeration trickle-leaching method was developed on a small scale and finally tried out in a 12-ton vat. Successful results were obtained as long as the leach solution was added slowly, so that the agglomerated charge was never flooded. If the leach solution flooded the charge, the glomerules broke down and the charge became impervious. There are two important difficulties in the application of the agglomeration trickle-leaching method to the cyanide process for gold and silver ores:

Jan 1, 1937

By P. R. Sheorey

I read this interesting paper on pillar strength in some detail because this is also my area of interest. It has long been the desire of mining rock mechanicians to predict pillar strength from laboratory compression tests. Considerable literature is available on compression strength of rocks and coal but many of these experiments were conducted not for pillar design but for rock behavior. I have a few comments on the author's approach to pillar design, especially equation (33). Two important factors, which the author seems to have excluded, can be added to the right side of equation (2): time-dependence of strength and the influence of mine environment on strength (moisture and weathering.) The author has taken considerable pains to analyze a large amount of testing data in [Table 1], yielding the various exponents ci of equation (2) (or the subsequent equations derived from it.) He has, however, not shown by means of a worked out example how these values of [Table 1] could be applied to a practical pillar design situation. It would have been interesting to compare predicted pillar size using equation (33) with an actual case. Alternatively, equation (33) could have been used to explain the failure of a pillar, if such a case history were available. Consider we have a large number of case histories of stable and collapsed pillars in a seam and we conduct a large number of tests in a laboratory press. The exponents [ci] can then be determined for actual pillars as well as for test specimens. Thus, equation (2) will read [ ] Since laboratory testing conditions (e.g., between steel platens) are different from the conditions on pillars, the exponents [ci] in

Jan 1, 1983

By Paul Klopstock

(Butte Meeting, August, 1913.) THE Kennedy mining district is situated about 55 miles in a southerly direction from Winnemucca, and about the same distance south-east from Battle Mountain : two towns situated oil t the main line of the Southern Pacific railroad. History. Prospectors were first attracted to the district by the reported discovery of gold by Chinamen in Cinnabar creek in the early 90's. The prospectors came from the rich placer workings in and about American canyon ; but the new diggings were not found sufficiently rich to justify their being, worked as placer properties, and the prospectors started work in a number of places, looking for the veins which had fed the canyon. In 1893, Charles E. Kennedy, a prospector who had been attracted by the reported discoveries in the vicinity, left Hawthorne and came to the present site of the town of Kennedy. Within a short time he discovered the vein known as the Imperial, and proceeded, with the aid of some friends, to develop it. The vein was readily traced for a distance of about a mile, and about $10,000 worth of high-grade ore was shipped to the Utah smelters. At about the same time the Lawler Brothers, who had been prospecting in the district for some time, located the ?Gold Note group," which showed some extremely rich ore. Within a very short time they extracted from 'the Gold Note vein 150 tons of ore, which was shipped to the Utah smelters, and netted about $105 per ton above all expenses. Their good fortune attracted attention to the camp, and within .a short time a town was laid out, with a population of about 500 people. It was named in honor of Kennedy, who had made the first discovery of pay ore in the district.

Jan 6, 1913

By Orson Shepard

THE leaching method that was first widely used with the cyanide process consisted of percolation leaching of crushed ore in vats or leaching tanks. It was frequently necessary to separate the sand for cyanide treatment and discard the slimes, because only granular material allows the necessary amount of solution to percolate through it in a reasonable time. Later a slime process consisting of agitation followed by thick-ening and filtration was developed, and is extensively used to the pres-ent day. Even though the agitation-leaching slime process is considered satis-factory, the cost of plant and of operation are both greater than for a percolation-leaching plant of equal capacity. This situation has been recognized in the hydrometallurgical treatment of copper-bearing slimes; and a considerable amount of j work has been done at the Southwest Experiment Station of the U. S. Bureau of Mines in an effort to develop a percolation method of treating slimes. Experimental work on the copper-leaching problem was started by H. E. Keyes1, and later tests were made by J. D. Sullivan and A. P. Towne2. The Bureau of Mines work resulted in the development of a process by which slimes were moisture-agglomerated with sand and crushed ore, to form a permeable mass through which solution could be trickled without breaking clown the glomerules. The agglomeration trickle-leaching method was devel-oped on a small scale and finally tried out in a 12-ton vat. Successful results were obtained as long is the leach solution was added slowly, so that the agglomerated charge was never flooded. If the leach solu-tion flooded the charge, the glomerules broke down and, the charge became impervious. There are two important difficulties in the application of the agglom-eration trickle-leaching-method to the cyanide process for gold and silver ores:

Jan 1, 1937

By S. F. Frederick, G. F. Pittinato

The deformation mechanisms operating in Ti-5Al-2.5Sn at 20°K under uniaxial and biaxial stress fields were determined by using both optical and electron microscopy. In the uniaxially stressed specimens, de-fu~rnation twins were found only in the immediate vicinity of the fracture. Twinning was, however, established as a deformation mechanism under biaxial stress conditions. The same slip systems were opera-tiz,e under both uniaxial and biaxial stress. Prismatic slip was identified as the major slip syslem; however, basal and first-order pyramidal slip also occurred, but to a lesser degree. The interaction of moving dis-locations on intersecting slip planes resulted in the formation of jogs and dipoles. Hexagonal dislocation networks were formed only under biaxial stress conditions. A discussion is given on the formation of hexagonal dislocation networks. IT has been shown that titanium alloys can exhibit unusually high strengths when tested in a biaxial stress field.'-" The high biaxial strengths are a consequence of a strong basal plane sheet texture which results in distinctly anisotropic flow properties. This texture strengthening appears to decrease with decreasing temperature2 and would seem to indicate a change in deformation modes. For example, in a uniaxial tensile test, Ti-5A1-2.5Sn yields isotropically at 20°K but is strongly anisotropic at room temperature. The increase in biaxial ultimate over uniaxial strength at 20°K is also much less than at room temperature. It is known that titanium car] form deformation twins more readily at cryogenic temperatures than at room temperature.4 Since the formation of deformation twins will reduce the degree of basal texture in sheet material,' an accompanying decrease in texture strengthening would be expected. To investigate more fully the nature of texture strengthening at cryogenic temperatures, the deformation modes of Ti-5A1-2.5Sn tested in uniaxial and 1:1 biaxial tension at 20°K were studied by optical and electron transmission microscopy. EXPERIMENTAL PROCEDURE The uniaxial and biaxial stress test specimens were prepared from 0.020-in. thick sheets of Ti-5A1-2.5Sn ELI having the composition shown in Table I. Uniaxial stress conditions were obtained by using flat tensile specimens machined from the sheet material. The longitudinal axis of the tensile specimens was aligned perpendicular to the rolling direction of the sheet. Tile biaxial test specimens were prepared by rolling precut, 19-in.-lengths of sheet into 4-in.-diam cyl- inders. Following longitudinal butt welding, the cylinders were stress relieved at 1000°F for 4 hr. A 9-in. sq "window" was then chemically milled into each cylinder's surface reducing the wall thickness in the milled area to approximately 0.006 in. The testing procedure consisted of pressurizing the cylinders while simultaneously applying a tensile load. Using this technique, a 1:l axial to hoop stress was obtained. Complete details of the specimen and testing procedures are given in Refs. 1 and 2. The biaxial and uniaxial stress specimens were all tested in liquid hydrogen. Specimens for electron transmission microscopy were prepared by first chemically milling to a thickness of about 0.001 in. followed by electrolytic polishing to electron transmission thickness. The chemical milling solution, consisting of 800 ml of water,

Jan 1, 1970

By Godfrey T. Vivian

Very often important discoveries are made in one industry that may be used to advantage in another, but, owing to the rarity that men step out of one industry into another, these discoveries remain unknown outside of the trade or profession in which they are made. The present paper is written solely with the object of bringing to the notice of mining and metallurgical engineers a centrifugal ore-concentrator which eventually may have a great application. Ore- Grading. Fig. 1 represents the action which takes place when solids of different dimensions are stirred up in a box and allowed to settle as minerals of the same size but of different specific gravity. This principle is applied practically in grading china-clay and in enriching tin-slimes. In the latter case the slimes are stirred around in a tub with water and allowed to settle while at the same time the side of the tub is struck with a hammer. The colloidal slimes are then poured off and various slices taken off horizontally. The great drawback of this process is that the particles are deposited horizontally and all the colloids are lost. Fig. 2 represents the action in which the particles are deposited side by side. Here the drawback is the great length of the box needed in order to prevent excessive loss. The alternative to lengthening the box is to increase the force of gravity. Centrifugal force may be regarded practically as the force of gravity augmented. Fig. 3 illustrates the Gee centrifugal machine for grading ores. The drum, A, fitted with a box, B, is mounted on a shaft or spindle, C, the whole being suspended from a ball-bearing of special design at D, supported between girders, E. Rota-

Jan 1, 1913

By G. W. Housner

The series of earthquakes in the vicinity of Koyna Dam in south- western India, which included a very damaging magnitude 6.5 shock on Dec. 11, 1967 (Dec. 10 GMT), is of much interest. The events are exceptionally well documented, which is a tribute to Indian geologists, seismologists, and engineers. To help in disseminating the information in the United States, this chapter presents a brief summary of the pertinent data and lists references. Koynanagar (Koynatown), which began as the construction camp for the dam, is located about 140 miles southeast of Bombay and 70 miles south of Poona at 17.4ºN and 73.7ºE, about 40 miles inland from the Arabian Sea. Koyna River flows almost due south from its source a distance of about 38 miles and then makes an abrupt turn to the east and travels some 480 miles to empty into the Bay of Bengal. Koyna Dam is located about 3 miles north of this turn. The approximately north-south trending continental divide is a few miles west of Koyna and the terrain drops steeply about 1700 ft to where the hydroelectric generating station is located. The reservoir behind Koyna Dam forms a long, narrow lake (Shiva- jisagar Lake) with mean water level (MWL) at 2160-ft elevation. The 345-sq-mile watershed receives an annual rainfall of about 200 in., most of which falls between mid-June and mid-October. The peak storage is 99 x l09 cu ft. A controlled flow passes under the continental divide in a tunnel and then down to the electric generating station about 5 miles WNW of the dam. The inflow not used for power generation is released to Koyna River. The Koyna project is a major source of electric power for Bombay and produces 540 MW at peak load.

Jan 1, 1970

By S. Weissmann, P. R. Swann, D. F. Wriedt

The sizes and density of precipitates in an intemally oxidized 0.19 wt pct Al-Ag single crystal have been determined by low-angle X-ray scattering and by transmission electron microscopy . The correlation in particle sizes measured by the two techniques is reasonably good. For an oxidizing temperature of 800°C the particles were found to INTERNAL oxidation of dilute alloys of aluminum in silver produces an oxide which has an excess of oxygen compared to Al2O3.' It is believed that the excess oxygen is an indication of the small sizes of the oxide particles. Depending upon the particular model chosen for the oxide structure, the size of the o-A1 particles can be calculated as a function of the oxygen-to-aluminum ratio. These calculations pre- have diameters in the range 30 to 140A, with a mean size of about 50.4 as observed by electron microscopy. At lower oxidizing temperatures, less than 600°C, no clearly resolved particles are formed, and it is suspected that if A1-0 clusters exist they must be exceedingly small, i.e., 10A or less in diameter. dicto that the particles would vary in size from 15 to 100A. This range of sizes is amenable to detection by both small-angle X-ray scattering and transmission electron microscopy. This paper compares the cluster sizes in such internally oxidized A1-Ag alloys determined by transmission electron microscopy and small-angle X-ray scattering. SPECIMEN PREPARATION Single crystals were prepared from 99.9999 pct Ag, obtained from Cominco Products, and 99.99 pct Al, obtained from Aluminum Co. of America. All melting operations were carried out in graphite molds under flowing purified hydrogen in a horizontal zone refiner. The silver was first degassed,

Jan 1, 1964

By R. Dawson Hall

THE stresses in the e simplest structures are often those we find most difficult to analyze. The most complex condition in mine stresses is found in simple tunnels where the roof, the sides, and the floor are a monolith. The functions of the parts are like the parts themselves not distinct and specialized, and the problems to be solved are like those in a metal structure with riveted joints or a redundancy of bars. This difficulty explains perhaps why the condition has not been treated. But just because it cannot be discussed in its entirety is no reason why it should be treated as an action of parts with specialized functions as a roof 'beans with supports and a foundation. The problem cannot be ignored on the ground that it is not of sufficient importance to warrant careful consideration, because conditions of complete monolithism, of which the tunnel is the type, are found materially unchanged) in room-and-pillar and in longwall work. This unity between roof, sides, and floor, which to the coal miner is a difficult conception, really deserves a scientific appellation, and perhaps holoid (from holos, whole, and eidos, form) will serve the purpose as well as any other. In a simple tunnel the roof, the sides, and the floor form integral parts of one and the same structure; and the distortion of one cannot be conceived without a consequent strain in the others. Thus when the roof of the tunnel droops by reason of its weight, the upper parts of the sides are drawn in because they are integrally-connected with the roof and must approach each other whenever, by the sagging of the roof, the distance between any two points in it is diminished. (See Fig. 1.)

Jan 9, 1915

By S. R. Maloof

In 1945, Hollomon' showed that after plastic yielding and prior to necking under simple tension, both ferrous and nonferrous materials are approximated by an equation of the following form: where, a = true stress K = strength coefficient 5 = true strain n = strain hardening exponent If a material is stress free, a plot of log o vs log 6 would be expected to be a straight line, the slope of which is the strain-hardening exponent (n) and the intercept on the ordinate axis for 6 = 1. is the logarithm of the strength coefficient K. It can be easily shown that the strain-hardening exponent in the above equation is equal to the total uniform elongation prior to necking. Thus, one can determine the total uniform elongation prior to necking from such a plot and, as pointed out by C. W. MacGregor, 2 it is the amount of strain prior to necking which determines the extent to which a material may be deep drawn. In the view of the current interest in the fabrication of beryllium shapes, it was thought that a knowledge of the strain-hardening exponent of cross-rolled beryllium sheet would be of general interest. Load-strain data after yielding and prior to necking was taken from the work of Greenspan,3 converted to true stress and true-plastic strain, and plotted on log-log paper as shown in Fig. 1. The value of Young's modulus E for beryllium was taken as 43 . l06 psi. The slope of this plot gave a value of 0.212 for the strain-hardening exponent (n) and the intercept on the ordinate axis a value of 105,000 for K. The total uniform elongation is thus 21.2 pct, in excellent agreement with the value estimated by Greenspan (about 20 pct). Furthermore,

Jan 1, 1960

By A. B. Calhoun

These mines, which belong to the Burma Corporation, Ltd., formerly a London company now incorporated in Rangoon, Burma, are situated in the semi-independent state of Tawng-Peng, one of the small divisions comprising the northern Shan states and erroneously known as part of Upper Burma. Bawdwin is approximately 23' 6' N. latitude and 97" 20' E. longitude, 450 miles north of Rangoon, 169 miles northcast of Mandalay and 50 miles south and west of the Province of Yunnan, China (see Fig. 1). Although the mines were worked by the Chinese during the Ming Dynasty, 1412 A. D., the most extensive operations took place between 1796 and 1851, when the mines contributed largely to the silver market of China. During the reign of Tung Chik, 1868 A. D., they were abandoned partly because of the Mohammedan rebellion in Yunnan, which made life and property insecure, but largely because of the difficulty of operating the mines on account of water and poor ventilation. Since that time practically nothing was done, although the Burmese kings are said to have made several sporadic attempts to work the mines, until 1891 when Europeans were attracted by the great slag dumps (assaying about 40 per cent. lead) which the Chinese had left after extracting the silver. After a railroad and smelter had been built and 200,000 to 300,000 tons of slag smelted for lead, exploration work was started and old workings cleaned out in order to locate the remnants of the orebody that it was supposed the Chinese had left. After two years of most discouraging work, the remains of a large orebody was discovered by the Dead Chinaman Tunnel or what is the 171-ft., or No. 2 level adit. From then on the development was rapid and today the Chinaman is considered one of

Jan 1, 1923

By A. B. Calhoun

These mines, which belong to the Burma Corporation, Ltd., formerly a London company now incorporated in Rangoon, Burma, are situated in the semi-independent state of Tawng-Peng, one of the small divisions comprising the northern Shan states and erroneously known as part of Upper Burma. Bawdwin is approximately 23' 6' N. latitude and 97" 20' E. longitude, 450 miles north of Rangoon, 169 miles northcast of Mandalay and 50 miles south and west of the Province of Yunnan, China (see Fig. 1). Although the mines were worked by the Chinese during the Ming Dynasty, 1412 A. D., the most extensive operations took place between 1796 and 1851, when the mines contributed largely to the silver market of China. During the reign of Tung Chik, 1868 A. D., they were abandoned partly because of the Mohammedan rebellion in Yunnan, which made life and property insecure, but largely because of the difficulty of operating the mines on account of water and poor ventilation. Since that time practically nothing was done, although the Burmese kings are said to have made several sporadic attempts to work the mines, until 1891 when Europeans were attracted by the great slag dumps (assaying about 40 per cent. lead) which the Chinese had left after extracting the silver. After a railroad and smelter had been built and 200,000 to 300,000 tons of slag smelted for lead, exploration work was started and old workings cleaned out in order to locate the remnants of the orebody that it was supposed the Chinese had left. After two years of most discouraging work, the remains of a large orebody was discovered by the Dead Chinaman Tunnel or what is the 171-ft., or No. 2 level adit. From then on the development was rapid and today the Chinaman is considered one of

Jan 1, 1923

By F. N. Lathe

In 1882, The Arizona Copper Co., Ltd., acquired producing copper mines at Metcalf and Morenci (locally called Longfellow). Metcalf is situated a distance of 7 miles, and Morenci a distance of 6 miles from the general office of the company at Clifton, Ariz. A reduction works with five blast furnaces was built in the center of the town of Clifton in 1884 and operated until January, 1914. Concentration of oxidized ores was begun in 1890-1891, in a mill built adjoining the smelter, and id October, 1893, a leaching process was started for treating tailings from the oxide mill. A sulphide concentrator with 300 tons capacity was built at Clifton and started treating chalcocite ores in July, 1896. This was the first mill to treat low-grade copper-siilphide ores successfully. Another concentration mill for sulphide ores was erected at Morenci in 1900. The sulphide mills are now being remodeled to treat ores by concentration and flotation, with a capacity of 4,000 tons at Morenci and 500 tons at Clifton. The leaching plant has not been running since September, 1914. The average yearly production from this company's mines and reduction works from 1885 to date has been: Pounds 10 years ended 1894................................... 6,864,902 10 years ended 1904................................... 20,439,614 10 years ended 1914................................... 32,665,905 Part of year 1915, to Sept. 12........................... 30,206,106 4 months of 1916, to June.............................. 15,964,840 June, 1916........................................... 4,900,000 Construction on a new smelting plant was started in February, 1912, and finished in February, 1914. In the Transactions, vol. 49, E. Horton Jones published "Unit Construction Costs from the New Smelter of the Arizona Copper Co., Ltd.," which fully describes the construction of this plant, with details of costs.

Jan 1, 1917

ASIDE from the John Fritz Medal, in which the Institute partici¬pates through its representation on the John Fritz Medal Board, the Institute itself has four awards it may make annually, as fol¬ lows the Robert W Hunt Medal and Prize, the J E. Johnson, Jr , Award, the James Douglas Medal, and the William Lawrence Saun¬ders Medal ROBERT W HUNT MEDAL AND PRIZE The partners of Robert W Hunt established a fund which was, presented to the Institute at a fitting ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded tinder the following rules¬ 1 The award shall consist of two prizes first of a gold medal, second of a sum of money, a certificate to accompany each prize The money prize shall not be awarded to a member' over 40 years of age, but under unusual circumstances, both prizes may be allotted to one per son provided that he is not over 40 years of age In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal 2 The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best original paper or papers on non and steel The scope of the term "iron and steel" shall be determined by the sub-committee consideing the awards In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt's main con¬ti ibutions to the industry have been in the improvement of production and quality of material

Jan 1, 1923

ABIDE from the John Fritz Medal, in which the Institute participates through its representation on the John Fritz Medal Board, the Institute itself has three major awards to make annually and one special prize for excellence in technical papers, as follows. The Robert W. Hunt Medal and Prize, The J. E. Johnson, Jr., Award, the James Douglas Medal, and The Lewisohn Platinum Prize to senior members. ROBERT W. HUNT MEDAL AND PRIZE The partners of Robert W. Hunt established a fund which was presented to the Institute at a fitting' ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded under the following rules ? 1 The award shall consist of two prizes, first of a gold medal, second of a sum of money, a certificate to accompany each prize. The money prize shall not be awarded to a member over 40 years of age, but under unusual circumstances, both prizes may be allotted to one person provided that he is not over 40 years of age In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal. 2 The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best original paper or papers on iron and steel The scope of the term "iron and steel" shall be determined by the sub-committee considering the awards In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt's main contributions to the industry have been in the improvement of production and quality of material

Jan 1, 1923

By J. A. Bartnik, Gerald D. Rose, William H. Benson

New techniques in the magnetite and heavy media beneficiation industries demand more efficient magnetic dispersion and flocculation of the finely ground particles. Demagnetizing coils must produce several major effects, such as improving classification and screening efficiency, decreasing moisture content in filter cake and improving separation selectivity and green pellet properties. Likewise, magnetic flocculators must increase filtering rates and the settling rates of solids, improve magnetite recovery and produce cleaner water. To improve the design of equipment and to conduct tests leading to the optimization of such dispersion and flocculation, a program was initiated at Eriez Magnetics. The major conclusions reached are: 1. Laboratory and plant scale tests conducted on magnetite products show that a demagnetizing force of 450 rms oersteds at 60 cycles for 1/20- second duration will depolarize natural magnetite particles coarser than approximately 10 microns. This has been found satisfactory for most applications. 2. Effective flocculation of magnetite was obtained when a slurry with more than one percent magnetite was exposed for a period of approximately 1/15 second to a 600-gauss field. 3. The cost of demagnetizers (or flocculators) increases rapidly for larger diameter pipes. In order to reduce the cost, narrow rectangular sections are recommended for magnetic flocculators. 4. For minimum operating cost, permanent magnetic flocculators are ideal, chiefly because they do not require any maintenance and have no operating cost. 5. A newly designed electro-demagnetizing coil with high heat dissipation and a nonmetallic core provides high efficiency and long life. 6. To select the correct magnetic flocculator (or demagnetizing coil) the following information is necessary: a. Magnetic product susceptibility b. Magnetic product coercive force c. Percent of magnetic product d. Flow rate e. Viscosity f. Structure of magnetic product

Jan 8, 1968

All the TECHNICAL PUBLICATIONS and CONTRIBUTIONS published in 1933 are available at Institute headquarters, unless otherwise noted. They are also on file in many public, university and technical libraries and, when so indicated in the list, may be found in the TRANSACTIONS. Copies of the TECHNICAL PUBLICATIONS have been mailed to those members of the Institute who are registered in the different classes: A-Metal Mining; B-Milling and Concentration; C-Iron and Steel Division; D-Nonferrous Metallurgy;. E-Insti¬ tute of Metals Division; F-Coal Division; G-Petroleum Division; H-Nonmetallic Minerals; I-Mining Geology; J-Mineral Industry Education Division; K-Mining Administration; L-Geophysical Prospecting. Other members may obtain copies by writing to the Secretary. Copies of CONTRIBUTIONS may also be obtained from the Secretary's office. Additional copies are sold at the rate of 1 cent per page; minimum charge, 25 cents. Nonmembers may purchase the papers at the prices mentioned. METAL MINING TECH- NICAL PUBLI- TITLE AUTHOR MEETING TRANS. CATION VOLUME No. AND PAGE* 499-A.47 Red Ore Mines of the Woodward T. C. DeSollar New York, Iron Company at Bessemer, Feb., 1933 Alabama (11) CONTRI¬ BUTION No. 1-A The Owyhee Tunnels (16) P. R. Hines New York, Feb., 1933 2-A Sinking and Equipment of the No. D. D. Homer New York, 2 Shaft at Minas de Mata- R. H. Cromwell Feb., 1933 hambre (25) 3-A Subsidence Resulting from the Charles W. Allen New York, Athens System of Mining at Feb., 1933 Negaunee, Michigan (8) 4-A Effect of Approximately Vertical P. B. Bucky New York, Cracks on the Behavior of Hori- Feb., 1933 zontally. Lying Roof Strata (16) 21-A Selection of a Mining System (11) R. K. Warner New York, Feb., 1933

Jan 1, 1933