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LANS are underway for the annual meeting of AIME, to be held in New York, February 17 to 21. The technical program includes meetings of all divisions of all three branches, Mining, Metals, and Petroleum. The bulk of the technical sessions will be held at the Statler Hotel, and the annual banquet will be held at the Waldorf-Astoria, Wednesday evening, February 20. The technical program of the Mining Branch activities is included in this issue. While it is not complete in every detail, it shows general interest groupings as well as subjects to be discussed. The program for each division is shown separately to facilitate following the activities of these special interest groups. Then, after a full scale and possibly somewhat strenuous technical meeting, a post-meeting feature will appeal to many of the members. A restful cruise to Bermuda and Nassau is offered at special rates to AIME members and friends. The schedule is a 3:00 pm departure from New York on the Queen of Bermuda on Saturday, February 23; arrival at Bermuda at 7:00 am Monday, February 25; arrival at Nassau at noon, Wednesday, February 27; and the trip ending again in New York at 9:00 am, Saturday, March 1. Rates begin at $202.10 per person, with higher rates depending upon accomodations desired. The base rate includes outside room with private bath and all meals, as well as Federal, Bermuda and Nassau taxes. Reservations for the trip should be made immediately through Leon V. Arnold, 36 Washington Square West, New York 11, who is in charge of arrangements.

Jan 1, 1952

By Henry J. Miller, Marcella Linderman

During some experiments made by Henry J. Miller, partly in Germany and partly in the United States, in which it was found necessary to melt metals in quantities up to 60 kg. in a vacuum or under low pressures of hydrogen, molybdenum was tried as the resistor in the electric melting furnaces. Molybdenum ribbons 16 by 0.55 mm. and 18 by 0.45 mm. were used as resistors. The furnaces were of the type shown in Fig. 1. About the heating tube, Y, are wound parallel resistors of molybdenum ribbon from the water-cooled electrodes, El, Ez. The whole is within a copper container having outlets for the removal or introduction of gases and a window, W, for observation, the space about the heating tube and electrodes being filled with insulating material. The life of the molybdenum used as the resistor was found to depend very much on the manner of using it, its failure being due in some cases to thinning by evaporation or chemical reaction and in others to hardening, which prevented it from following the expansions and shrinking of the heating tubing without cracking. As such failures are often rather expensive in commercial work, it was thought worth while to determine the causes. The factors influencing the behavior of molybdenum resistors used in this manner may be briefly stated as follows:

By H. Shaw

Gravitational measurements made by means of the Eotvos torsion balance over any area enable a representation to be obtained of the total gravitational effects over the surface of that area arising from the combination of all sources of gravitational disturbance. The investigation of gravitational anomalies occurring in the upper layers of the earth's crust, in this way, has been attended with considerable success, and, especially in areas in which no undesirable disturbing factors were present, it has been possible to locate geological structures and mineral deposits with remarkable accuracy and also to delineate their confines and to indicate their depth below the surface with a certain amount of precision. Before this can be done successfully, however, it is necessary to determine the gravitational effect arising from all other extraneous anomalies in order that these may be satisfactorily eliminated. Disturbing features giving rise to these gravitational anomalies may be divided into two classes, according to whether they are situated at or below the surface. The former are determined readily by a detailed leveling of the ground surface, and may be satisfactorily eliminated provided the specific gravity of the terrain material is known, but the latter are generally unknown, and can only be ascertained with difficulty. When, therefore, the observations obtained by means of the Eotvos torsion balance have been corrected for all surface irregularities, known as terrain and topographical effects, there remain residual gravitational values which are due entirely to subterranean conditions. The. task of interpreting these results consists in disentangling the various subsurface anomalies, and subsequently in computing and recombining the effects of these various masses in order to verify the interpretation. When the gravitational anomalies are due to large and comparatively simple structures it is a matter of little difficulty to arrive at a satisfactory interpretation of the subterranean conditions, but in more complex areas, where the geological conditions are more complicated and several irregular features exist, the process of disentangling the various constituents of the complex mass arrangement is more difficult and requires the expenditure of considerable time and labor. When the subterranean effects have been obtained, they are subjected to a critical examination, and an effort is made to recognize and

Jan 1, 1932

By Arthur Knapp

No oil territory in the world has been so rich in large producing wells, in a comparatively small area, as the Baku field. Particularly is this true of the Bibi Eibat field, which formerly produced millions of "poods," of " gusher," or as it is called in Russia, " fountain " oil. The Bibi Eibat and Balachany fields have been exhausted of gas and ruined by water, but the Surachany and Benegadi fields are still fountain territories and many outlying districts that have only been prospected produce rich fountains. The method of controlling fountains, or gushers, is the result of growth, along with the Russian system of drilling, where large diameters and riveted casing have been in vogue. The screw casing is seldom used except to exclude water. Formerly the method of finishing wells and the condition of the casing at the top of the well would not permit the use of gates, manifolds, and connections as is standard elsewhere. The life of the flowing wells is very short, particularly those 10 in. (25 cm.) or more in diameter, which produce large quantities of sand and often flow for but a few days and are then a complete loss. More than 1,000,000 poods in 24 hr. have been claimed in several instances, but in no case was the flow for more than a few days. The oil sands of this district are free uncemented sands and vary in thickness from paper thin to a maximum of 10 ft. (3 m.). The sands are interlaid with strata of soft clay. In spite of this, the practice has been to drill into such sands and produce from the open hole without screen or liners. Sometimes the casing is set below the oil sand but in this case holes from 2 ½ to 3 in. in diameter are drilled opposite the oil sand, which would not have the effect of a screen.

Jan 1, 1920

By D. H. Davis

HAND picking was the earliest form of coal preparation, first practiced to improve the outward appearance of the coal being loaded and to remove any pieces that might appear objection- able to the buyer. It is still extensively practiced on the plus 1-in. sizes and particularly on the plus 4-in. and larger sizes. The percentage of ash reduction that can be obtained by hand picking depends entirely upon the amount of free impurity occurring in the coal. In a particularly dirty seam, where a considerable quantity of rock occurs with the coal as mined, hand picking produces sizable reductions in ash. If the coal is prepared clean at the working face hand picking is a final check; in some cases, on the smaller sizes, it is practiced only to show that an effort is being made to prepare a clean product. Because of the variety and different methods of handling coal, the early plants were not always adapted for efficient hand picking. At most mines an attempt is made to remove the visual impurities at one or more of the following places in the surface plant? (1) in the tipple during screening; (a) on picking band, belt, or shaking conveyors;*(3) during the loading of the coal as it goes into the railroad car. Whatever the physical arrangements of the plant may be, the usual practice is to run the coal over the screen, picking table or boom at such a rate that each piece of impurity is exposed to the view of the picker. Coal should be uniformly sized and spread out on the table so as not to exceed one particle in depth. The flow should be even in tonnage and the speed of travel should be from 30 to 60 ft. per minute and not exceed 80 ft. per minute. The dirtier the coal, the slower the speed required for a fixed number of pickers. Actually, picking capacity depends on the number of particles per minute that can be picked out and rejected. The percentage of impurity removed is determined by this and the average weight of piece rejected. Handling a mixture of sizes from nut to the largest lump over the same picking table or conveyor is not conducive to efficient separation by hand picking because the lump hides the smaller

Jan 1, 1943

By Edward H. Robie

HOW have recent events affected the general trend in world mineral production? What effect has the World War, with its resultant boom and depression, had on the long-term trend of output? Have all of the principal metals and fuels been similarly affected, or have some boomed or slumped much more than others? The trend of world production of coal, iron, the principal nonferrous metals, and petroleum is shown in the accompanying chart, covering the period from 1882 to 1931 inclusive-the last fifty years. The curves are plotted logarithmically to show the comparative trends. In the lower left-hand corner of the chart is a slope diagram to aid in visually evaluating. the average yearly rate of increase in production; from this one can easily see, for example, that the petroleum production curve indicates an average annual increase of around 8 per cent, and that up to the period of the World War the average annual increase in copper production was about 6 per cent.

Jan 1, 1932

By Blamey Stevens

(San Francisco Meeting, October, 1911.) IN this paper, which is a logical extension of my paper, The Laws of Intrusion, 1 the various pressures of emanation and their mechanical causes and effects on the large scale of nature are determined, .and a classification of emanations is deduced therefrom. The Subterranean Sea. The subterranean sea is here defined as the intercommunicating water contained in the trains of pores and fissures of the rocks down to great depths. Whether the actual amount of water constituting this subterranean sea be large or small, does not enter into the present argument, since the static pressure of this water at any particular depth is not a function of the quantity : it involves only the depth and the density of the water. Densities. The total pressure at depths down to 10 or 15 miles is made up of the rock-stresses investigated in my previous papers, and the pressure of the subterranean sea. The latter component must evidently be equal to the weight of a solid column of the overlying water of unit sectional area. As water expands with heat, it should really be necessary to sum the density at every level. A knowledge of the densities of water under a variety of conditions is therefore needed, but does not seem ever to have been ascertained for such combined pressures and temperatures as we have to consider. The specific gravity of water at 28° C. for various pressures up to 400 atmospheres, has been determined by Barus,2 who

Apr 1, 1912

By Richard H. Jahns

Terminology and Basic Specifications Minerals and closely allied natural substances that are used for personal adornment, as raw stock for the fashioning of ornamental objects, or for other decorative purposes can be referred to collectively as gem materials. Industrial gem materials are those employed directly in various areas of industry. Substances that are manufactured for gem or industrial uses are termed synthetic gem materials; most of these correspond in composition and crystal structure to certain minerals found in nature. Imitation materials are those whose use is based upon their resemblance to substances of different composition and greater value. Gem stone is a designation commonly restricted to those materials suitable for personal adornment, and the complementary term ornamental stone is applied to the remaining materials not used industrially. This distinction is arbitrary and somewhat inconstant, owing to numerous geographic differences and historical shifts in end uses. Further, there is a complete gradation between the category of ornamental stones and that of dimension stone. Although many building and monumental stones are undeniably ornamental in their uses, treatment of such material is beyond the scope of this chapter. Substances that lose their identity in use are excluded from the gem category. Thus a transparent crystal of beryl would not be classed as a gem stone if it were treated as a source of beryllium metal. The adjectives precious and semiprecious have been employed as a means of distinguishing different gem materials on the basis of their recognized value. Diamond, emerald, ruby, and sapphire consistently have been regarded as precious stones, and in cut form they commonly are referred to as the noble gems. Opal, pearl, turquois, and chrysoberyl also have been classed as precious at various times. In recent years, however, it has been increasingly recognized that no satisfactory distinction can be based upon assessed value or any group of intrinsic properties, and at the present time all gem stones normally are referred to as precious. Indeed, the tendency is to extend this term to include many of the so-called ornamental stones, and the designation semiprecious has been essentially discontinued. Unlike most mineral commodities of economic value, gem materials are little altered in processing for end uses. Some stones are used in essentially their natural form, and most are reshaped and polished without significant changes in their fundamental properties. Thus the preparation of gem and ornamental stones is intended chiefly to emphasize or enhance desirable characteristics that are present initially. The worth of most synthetic gem stones is founded upon the identity between their major properties and the natural characteristics of the corresponding minerals, just as the pleasing qualities of imitation stones depend upon how well certain of their properties simulate those of more valuable substances. The most important specifications of gem materials represent four basic factors: beauty, durability, rarity, and portability. Beauty, whether expressed as splendor, "purity," attractiveness, or in some other way, is mainly a function of personal response to optical properties such as color, transparency, indices of refraction, and dispersion. Freedom from visible imperfections is important for transparent stones. For some substances beauty depends also upon asterism, opalescence, textural and

Jan 1, 1960

By M. A. Meyers, P. P. Meyers

The analysis of the phenomena involved in determining the compressive strength of iron-ore agglomerates leads to the identification of important parameters. It is shown mathematically that the pellet rupture strength is proportional to the cross-sectional area. Fracture is initiated at the center of the pellets by the tensile stresses developed by the compressive loads normally to the compressive axis. The variation in strength between individual pellets of identical composition and subjected to identical treatments u due to internal voids of varying sixes that act as stress-concentration sites. Two novel testing procedures are proposed. The first consults of testing the pellets between two plates having three steel spheres each. This configuration simulates much better the environment actually encountered by the pellets. The second procedure consists of a thick-walled cylinder in which a piston penetrates; a large group of pellets is tested simultaneously, as the stress versus strain plot is being recorded. This latter test presents vacant advantages over the conventional testing procedure; the main one is that one single test is sufficient to characterize the mechanical response of the pellets.

Jan 1, 1984

By H. S. Bell

It seems unnecessary to dwell upon the advantages of the modern pipe still as compared with the older type of distillation equipment used by oil refiners. The relatively low installation cost, coupled with remark-able operating efficiencies of pipe stills, precludes the consideration of other types except in rare instances where some peculiarity of product or plant may have an influence. The question of the actual heat required to distil petroleum is quite involved. We have extensive data on the latent heats of the various hydrocarbons under different conditions of pressure. We also have information regarding the specific heats of various oils and the effect of temperature thereon. Because of the complexity of petroleum and of each fraction, it seems impossible to analyze theoretically the partisl-pressure effect of the great number of hydrocarbons upon one another during distillation. If a distillation curve and percentage analysis of any crude or product are available, it is possible to construct a curve with ordinates representing per cent. distilled and B. t. u. per pound or per gallon, or other desired unit. To do so the crude is split into fractions, of 5 or 10 per cent. The boiling point and gravity of each fraction being determined, it is possible to evaluate the heat required. As each fraction is removed, the residue must be raised to a higher temperature and latent heat supplied for the successive fraction. As the calculations progress, the latent heats decrease while the specific heats increase. Such a curve is illustrated by Fig. 1 for a typical 39.9° Be. North Texas crude. The chart is illustrative of batch distillation. Theoretically, if the oil were heated by a single flash in a pipe still, the partial-pressure effect of the light products would result in the removal of the same amount of vapors at a lower temperature. Practically, we find that because of the necessarily extensive fractionating equipment required when separating many products all in vapor phase, the oil has to enter the separator at temperatures corresponding to or even above those required in the batch still. Furthermore, in single-flash distillation the vapors evolved in the heater must be superheated to the outlet temperature. Very little is

Jan 1, 1928

By Alden Greninger

THAT metallographic structures analogous to the martensite of steel may be found in certain copper-aluminum and copper-tin alloys has been known for many years; similar structures recently were found in certain copper-zinc alloys.1 In all three of these alloy systems the martensite structures result from transformation of the metastable ß phase when the speed of cooling from the ß range is sufficiently high to suppress decomposition into equilibrium phases. ? In the normal decomposition of solid solutions into equilibrium phases, diffusion is needed to bring about the necessary changes in concentration, and the rate of reaction falls almost to zero at temperatures slightly above room temperature. The rates of reaction for martensite processes, however, are not dependent upon temperature; the transformation does not require readjustments of concentration. For example, the marten-site transformation in 60:40 (ß) copper-zinc does not begin until the temperature has dropped to about minus 30° C., and then continues down to minus 130° C. and probably even at lower temperatures.1 Further-more, martensite processes apparently proceed only while the tempera-ture is falling, within the proper range, and cease completely while the temperature is held constant; ? and they cannot be suppressed by extremely rapid cooling although the rate of cooling for some alloys may be increased to over 10,000 times the critical cooling velocity. Isaitschew, Kaminsky and Kurdjumow2 account for these observed behaviors of martensite processes by postulating that the mechanism " . . . consists in a regular rearrangement of the lattice in such a way

Jan 1, 1939

By M. C. Udy, C. H. Lorig

THROUGH the years much interest has been centered in attempting to develop a direct method of iron-ore reduction, to replace or supplement the present indirect blast-furnace process. It would not be difficult to produce a list of more than 500 patents dealing with the direct production of iron and steel, but the few of this type of process that have proved successful do not produce in competition with the blast furnace; they produce special products. A survey of the literature reveals that the equilibrium conditions for the reduction reactions (iron oxides with carbon monoxide and with hydrogen) have been fairly well established but that data on the rate of reaction are discordant, although the general effects of the variables are known. This dissertation deals with the rate of reduction of a magnetite concentrate with hydrogen. The following variables have been studied: bed depth, gas velocity, particle size and temperature. The behavior of a single particle was also studied. LITERATURE Two general factors should he considered in a study of reduction of iron oxide: (1) equilibrium relations, and (2) rate of reaction. The first factor, equilibrium, has received the attention of many investigators and the equilibria Fe3O4-FeO-H2-H2O, Fe304-FeO-CO-CO2, FeO-Fe-H2-H2O, FeO-Fe-CO-CO2 are fairly well established. Of the second factor, the rate of reaction, much less is known. Data are comparatively scarce and there is very little concordance. The discordance probably results from the large number of variables influencing the reactions. However, the general effect of the variables is known. Among these variables are temperature, gas velocity, particle size, porosity, gas composition (distance from equilibrium), presence of impurities, greater or less prevalence of side reactions, and even design of the apparatus itself. Wetherill and Furnas1 published an excellent paper in 1934. They point out that any one or more of five processes (the chemical reaction, diffusion of the reactant through the gas film, diffusion of the reactant through the solid phase, diffusion of the reaction product through the solid phase, or diffusion of the reaction product through the gas film) may be the slow process, and thus the rate-controlling process. It is regretted that the work of these authors was limited to experiments at one temperature, and that the range of gas compositions was limited. Langmuir2 has shown that heterogeneous reactions take place at phase boundaries.

Jan 1, 1942

By J. A. Woolf, E. S. Leaver

THE purpose of this paper is to describe, in a general way, gold-dredging operations in California, with particular reference to unusual features, including types of deposits and recent attempts to improve the recovery of the gold. Dredging Areas The gold-bearing formations that traversed the western slope of the Sierra Nevadas for a north and south distance of some 300 miles furnished the immediate source of the gold found in most of the placer deposits of California. Erosion through a long period carried the gold, together with various forms of partly disintegrated material, to lower elevations and formed placer deposits. Through the classifying action of water in motion, the coarser gold and heavier material of various kinds were - deposited relatively near the source; consequently, in the higher mountain country, old river channels were worked feverishly during the early California gold-rush days because of their high gold content. With the working out of these known high-grade channels, and from the knowledge thus obtained of prehistoric stream beds, drift mining was started and flourished until about 1890. Even today many drift mines are operating with the objective of opening other old Tertiary river channels that have been covered by volcanic flows. Adjacent to these areas, which contained relatively high gold values in the older river channels, smaller particles of gold, gravel, and debris were deposited along the sides of the former stream beds and on the adjoining flat areas, thus forming the large placer deposits, which were worked principally by hydraulic mining. Following the course of the ancient rivers and of the present drainage system to the lower edge of the foothill country, extensive areas of alluvial

Jan 1, 1937

By Norman Brown, J. V. Rinnovatore

Substructures in explosively deformed and annealed ß brass have been examined by electron microscopy. In the explosively deformed condition, the structure contains a large density of straight screw type dislocations. Subsequent annealing up to 300oC produces low angle boundaries, which are characterized by superlattice dislocations, and expanded and contracted nodes. Evidence is given where two a(111) superlattice dislocations combine to form two a(001) superlattice dislocations. It is also shown that annealing at 400°C the networks disappear and that quenching from 400" C produces square and circular prismatic dislocation loops that lie on (100) and (111) planes, respectively. THE purpose of this work was to determine the effects of explosive deformation and subsequent annealing in a superlattice using electron microscopy. One of the first observations of explosively deformed structures was made by Hornbogen1 on a iron. Hornbogen found that screw dislocations were most prominent in the explosively deformed structure. He explained this result by suggesting that the edge components of dislocation loops move with the velocity of the shock front leaving a trail of extended screw components. Kressel and Brown2 observed explosively deformed Fe3A1, which is basically a body-centered type of superlattice in terms of dislocation geometry, and found that, as in the case of iron, screw dislocations were most prominent. It was also observed2 that, in cold-rolled and explosively deformed nickel, screw dislocations did not predominate, but rather a uniform network of dislocations was present in which the orientation of the dislocations was random. (Cell structures also have been observed by Nolder and Thomas3 for copper and by Johari and Thomas* for nickel). Kressel and Brown2 discussed the difference between dislocation morphology for bee and fee metals in terms of dislocation mobilities. They suggested that edge dislocations have a greater mobility than screw dislocations in bee metals but not in fee metals. Thus, the idea offered originally by Hornbogen1 is not valid since it should apply equally to fee and bee systems but does not. The results of recent work by Mikkola and cohens on explosively deformed Cu2Au are consistent with other observations for fee metals. They found that dislocations were randomly arranged but there was no significant cell formation. At high shock pressures, deformation twins are produced in fee metals.' High pressures in bee metal should induce the bee — fee transformation while the metal is under pressure. EXPERIMENTAL PROCEDURE The Cu-Zn alloy used in this work contained 51.4 wt pct Cu. Specimens of 0.5 in. diam and 0.012 in.

Jan 1, 1968

By James C. Ray

The age classification of the mineralized veins of the Butte district, as given by Weed and Sales, was tacitly accepted for many years. Weed, whose field work was completed in 1906, divided the copper veins into groups of four ages.' In 1913, Sales modified Weed's classification and assigned all mineralized veins (including the silver-zinc veins of the border or "peripheral" zones) to three periods of fracturing and mineralization. Both writers based their classifications mainly on the relative ages of the observable faulting whereby the veins of a so-called "earlier" system are intersected and offset by those of a "later" system. Nevertheless they possess structural and mineralogical characteristics in common which indicate that they are of the same age. The writer has maintained since 19143 that these vein systems were formed during one general period of mineralization along a network of intersecting fractures of approximately simultaneous origin and that the existing offsets are largely due to postmineral faulting. Leith,* takes cognizance of the accumulating mass of data relative to the simultaneous formation of intersecting fracture systems and says, referring to ~utte: "It now appears that the mineralization accompanying them (individual structure systems into which the veins have been grouped) is substantially of one period, indicating that the successive structural movements took place mainly within the period of mineralization." This paper presents the results of certain structural experiments which suggest a modified interpretation of the published data on the Butte district. The interpretation is substantiated by the writer's observations in the Butte mines and is offered with the hope that it will reconcile the structural with the mineralogical conditions existing in this most interesting district; also, that it will emphasize the importance of a

Jan 1, 1931

By V. W. Aubel

AMONG the iron-bearing ores of the world, the titaniferous iron sands of New Zealand are probably the least known to American engineers. This is not surprising in view of the fact that. American ironmasters look with disfavor on any, even domestic ores, containing over 1 per cent. titanium. The possibilities of smelting titanium-bearing ores in the blast furnace are still undetermined, but the problem of their efficient reduction is becoming more important each year. There seems to be little inclination on the part of American furnace operators to tackle this problem, and they will no doubt continue to utilize the non-titanium ores at their command, leaving research and experiment to those countries not so fortunately endowed. New Zealand has, however, been intensely interested in her deposits of titanium,bearing iron sand, and during the last 50 years considerable English and New Zealand capital has been expended on this problem. The extent of the New Zealand iron-sand deposits is almost beyond measure. From Patea north to Manuka Heads, along almost the entire west coast of the, north island, these deposits exist. Wherever there is beach sand along this 300 mi. of coast line, the sand is iron bearing. It varies considerably in grade; but wherever the contour of the coast affords small bays and inlets, large dunes are found that are remarkably uniform in quality. Several of these large deposits, especially those at New Plymouth and Patea, are noted for their high iron content. The dune at New Plymouth runs between 55. and 60 per cent. of metallic iron; the panning action of the prevailing westerly winds and northwesterly currents has no doubt resulted in this concentration. Whatever the origin of this material may be, there is no doubt that deposition is going on continuously. At New Plymouth, a small artificial harbor, protected from the drifting sand by a large breakwall, has been dredged. Here sailing vessels have for years been loaded with iron sand for ballast by means of a crane and grab bucket operated from the wall of the breakwater. Thousands of tons of sand have been removed from this spot

Jan 9, 1919

By W. W. Lowry, G. C. Eggleston, W. E. Keck

THE potential iron ores of Michigan can be classified from the stand- point of the predominant impurities into siliceous, sulphurous and phosphorous ores. Research on the flotation of each of these classes of ore was carried out in the following manner. The flotative properties of the valuable minerals of iron and of the worthless and deleterious ones were first determined under carefully controlled conditions. This information was then applied to synthetic mixtures of these minerals, which simulated the potential ores. Finally, data obtained during the two foregoing stages of the investigation were used in the flotation beneficiation of samples of the potential ores. Hematite is the most important mineral of iron in each of the above classes of iron ores. This paper deals with a study of that mineral in the very nearly pure state. There are two varieties of the mineral-specular hematite and massive hematite. The latter is the principal variety, but the former is an important mineral of iron in some of the potential ores. Because of this condition, flotation research was performed with both varieties. This research consisted essentially of: (1) a survey of the literature on hematite flotation, (2) the preparation of pure massive hematite, (3) the preparation of pure specular hematite, (4) the development of a laboratory procedure and (5) flotation experimentation. For the purpose of this discussion, the results of previous work on the flotative properties of hematite can be summarized as follows: Specular hematite has been readily floated with terpineol and sodium oleate or heptylic acid1. Further, hematite has been likewise floated with a proprietary frother and oleic acid or other soluble oils2. Finally, lead nitrate, copper sulphate, silver nitrate, chromium nitrate, mercuric chloride, ferric

Jan 1, 1937

By Gerald Edmunds, R. K. Waring, E. A. Anderson

Brass is liable to failure under the combined influence of stress, certain corrosion media, and time, a phenomenon commonly termed season cracking or stress-corrosion cracking. The consequences of this are serious in applications of brass generally, including the important field of cartridge cases. Cartridge cases (70 Cu: 30 Zn) that fail from this cause may allow the escape of gas from the gun breech, a hazard to the shooter, and may not eject, thus temporarily putting the gun out of action. In loaded cartridge cases, the stress present is partly residual from the, drawing and necking operations and partly applied by the insertion of the projectile. Ammonia, present as a decomposition product of smokeless powder, air and moisture constitute corrosive media. The prevalence of season cracking has been reduced considerably, but not eliminated, during the past quarter of a century by low-temperature annealing to relieve stresses residual from fabrication, a method suggested by Diegel 38 yr. ago(I).2

Jan 1, 1945

By V. F. Swanson

A petrographic study was made of the type and sources of mineral contamination occurring in Florida phosphate rock products. Emphasis was placed on contaminants in the screened rock (+1 mm), since this portion of the product undergoes no physical beneficiation except for scrubbing to remove slimes. Since iron and aluminum contents of the finished product affect the salability, special emphasis was placed on identifying types and sources of these contaminants and relating chemical composition to visual characteristics. Wavellite derived from the overburden was the major aluminum contaminant with some aluminum being included as secondary clay balls. Iron occurred as phosphates in the overburden and as colloidal oxides included in the phosphate pebbles. Chert and limestone contamination derived from the Hawthorne formation underlying the phosphate matrix.

Jan 1, 1972

By J. L. Craig, C. L. Edwards, M. D. Harper, J. M. Ray

The Los Alamos National Laboratory executed 19 intermediate scale cratering experiments in oil shale at the Colony Mine in Garfield County, Colorado. These experiments have led to a better under- standing of fracture characteristics and fragmentation of & - oil shale by use of a conventional high explosive. Geologic site characterization included detailed mapping, coring, and sample analyses. Site-specific geology was observed to be a major influence on the resulting crater geometry. The joint patterns at the experimental site frequently defined the final crater symmetry. Secondary influences included vugs, lithology changes, and grade fluctuations in the local stratigraphy. Most experiments, in both the rib and floor, were conducted to obtain data to investigate the fragmentation results within the craters. The rubble was screened for fragment- size distributions. Geologic features in proximity to the explosive charge had minimal effect on the rubble due to the overpowering effect of the detonation. However, these same features became more influential on the fracture and rubble characteristics with greater distances from the shothole. Postshot cores revealed a direct relationship between the grade of the oil shale and its susceptibility to fracturing. The Colony Mine experiments have demonstrated the significant role of geology in high explosive/oil shale interaction. It is probable that this role will have to be considered for larger applications to blast patterns and potential problems in retort stability in the future of oil shale development.

Jan 1, 1983