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By Alfred H. Bell, Charles W. Carter

In 1943, Illinois produced 82,256,000 bbl. of oil, or 5.5 per cent of the total for the United States, and ranked sixth in the nation in oil production. This represents a decline of 23 per cent from 1942, when the total Illinois production was 106,ggo,o~~ bbl. and Illinois ranked fifth. The daily average production for 1943 was approximately 225,000 bbl. Daily averages by months were as follows: Jan......... 238,000 July......... 218,000 Feb......... 240,000 Aug......... 216,000 Mar......... 237,qoo Sept........ 220,ooo Apr......... 230,000 Oct......... 220,000 May....... 221,000 Nov......... 223,000 June......; . 222,000 Dec......... z18,ooo This shows that most of the decline during the year took place between March and May, and that for the last eight months of 1943 production has been essentially steady. This means that there has been enough production from new wells drilled to balance the natural decline of the Older wells. The trends of drilling and production are shown in Fig. I and Table 3.

Jan 1, 1944

By Denton R. Wieland, Harvey T. Kennedy

The frequency of bubble formation is measured for oils from the East Texas field and the Slaughter field in cores from these fields. East Texas oil was also tested in a Slaughter core. The data checked previous results in that a definite supersatrtration may exist without the formation of bubb1es in periods of observation totaling 158 hours. Measured frequencies varied from zero at supersaturations below 14 psi to 3.1 bubbles/sec/ cu ft of rock at 40 psi supersaturation INTRODUCTION The formation of bubbles is essential in a solution gas-drive reservoir in the displacement of oil. In formations where the basic pore structure consists of fine pores or fractures connected to larger pores or crevices, bubble formation in the fine pores may be the most effective means by which the oil may be displaced, even if secondary methods are applied. The most efficient oil displacement would occur where at least one bubble would form in every pore. As the pressure decreased, the bubbles would expand, due to the gas diffusing into the bubbles, and displace the oil toward the lower pressure area around the wellbore. Kennedy and Olson' have shown that the total number of bubbles formed in a reservoir is primarily dependent upon the rate of pressure drop, the rate of diffusion of gas through oil, and surface area of the rock. The surface tension of the liquid and other characteristics of the rock may also exert an important effect, which would give a different frequency to different rocks and oils and various combinations of different rocks and oils. The purpose of this paper is to present frequency measurements on two rocks and two oils. A hydrocarbon liquid is at equilibrium with gas when it contains the maximum volume of gas in solution that it can have at the prevailing temperature and pressure. If the temperature is maintained constant and the pressure is reduced below the equilibrium pressure, the liquid is supersaturated to the extent of the difference in the two pressures until the gas comes out of solution as a free phase. As shown by previous work, and confirmed in the present investigation, the number of bubbles formed per second increases with an increase in supersaturation. Kennedy and Olson showed that a tenfold increase in the rate of pressure decline resulted in a tenfold increase in the number of bubbles formed per cubic foot of reservoir rock, e.g., for decline rates of 0.1, 1, and 10 psi/day, the number of bubbles formed per cubic foot would be 40, 400, and 4,000, respectively. For another hypothetical system, Stewart, Hunt, and Berry' estimated that for pressure declines of 0.1, 1, and 10 psi/day, the number of bubbles formed would be approximately 10, 100, and 1,000 cu ft of reservoir rock. Their value of bubbles formed is lower than given by Kennedy and Olson; however, the order of magnitude agreed satisfactorily. The rate of diffusion will also affect the number of bubbles formed. If the diffusion coefficient is high, the gas in solution in the oil surrounding a single bubble will tend to diffuse into the bubble rather than forming other bubbles. On the other hand, the formation of more bubbles will tend to occur if the diffusion coefficient is very low. In his thesis dated Aug., 1953, Wood" reports on the frequency of bubble formation in a system consisting of oil and rock from the Rangely field. In the present work, the apparatus of Wood was redesigned to allow greater precision, especially at low supersaturations, where bubble growth is slower, and detection is more difficult.

Jan 1, 1958

By David A. Thomas, Eugene S. Meieran

MECHAMCAL, electrical, and other property measurements are often more easily made on wires than on sheets. In order to carry out transmission electron microscopy on the same material used for property determinations, we have developed a method for preparing thin foil specimens of wires. The technique was developed for 0.030 in. diam tungsten wires, and is a modification of the thinning techniques used by Wilsdorf, et al 1 A length of wire is first ground to about 0.010 in. thick by mounting the wire in low melting temperature wax, hand grinding a longitudinal flat, removing and reversing the wire in the mount, and then grinding a second parallel flat. The 0.030 in. wide and 0.010 in. thick strip is cut into 1/8 in. lengths to fit in the specimen holder of the electron microscope. Next the specimen is gripped in platinum-tipped tweezers (the anode) and placed 2 mm below a hol- low copper cathode with a 0.010 in. ID nozzle. Electrolyte, 10 pct NaOH, flows by gravity feed through the nozzle onto the specimen, as shown in Fig. l(a). Polishing is carried out until a shallow impression is made on one surface, and then the specimen is turned over and the opposite surface indented. The metal between the two impressions should be about half the specimen thickness, as is shown by the heavy line in the cross section in Fig. l(b). The entire specimen is then electropolishedin 2 pct NaOH until a hole appears at the location of the indentations. The apparatus is shown in Fig. 2, and is essentially the same as that used by Wilsdorf et al. at The Franklin Institute. Light is reflected by a mirror onto the bottom surface of the specimen! which is viewed by a stereoscopic microscope placed above it. Polishing is carried out until light is seen, indicating that a hole has formed, and then immediately stopped. The specimen is washed in water. alcohol, and ether, and is then ready for examination. The specimen should be reversed in its platinum clip during electropolishing to insure equal polishing on both sides of the impression. For tungsten, indenting at 120 v and 0.04 amp takes less than 1 min, and final polishing, at 10 v and 1 amp, less than 5 min. The portion of the specimen available for transmission microscopy surrounds the hole, as is seen by the dashed lines in Fig. l(b). Slight electroetch-ing accompanying electropolishing reveals the mi-crostructure, as seen in Fig. 3(a) by light microscopy. Low-magnification electron microscopy, as in Fig. 3(b), enables the same areas and grains to be viewed and identified when subsequently examined at high magnification. Fig. 4 is a typical structure of

Jan 1, 1963

By John M. Dealy, Robert D. Pehlke

Values for interaction parameters in nonferrous systems, as calculated from published data, are tabulated and discussed. The influence of temperature on the parameter is derived and compared with the results of the literature study. Wagner's relationship between the interaction parameter and the self interaction coefficients is compared with the tabulated data. A problem which has been of considerable interest in the field of metallurgy is the prediction of the effect of one alloying element present in dilute concentration on the thermodynamic properties of another dilute alloying element. Ultimately, the prediction may be accomplished entirely from statistical mechanical considerations. At the present, however, the problem remains unsolved since liquid solution models which are simple enough for analytical treatment are inadequate for such purposes. Thus, we desire some means of organizing the information on dilute systems which will serve as a guide for further study on interactions in dilute alloys, and also provide a basis for the utilization of thermodynamic data in the engineering design of alloys.

Jan 1, 1963

By John Hays, Hammond

IT is both a pleasure and an honor to be a guest of the Institute and I thank you, Mr. President and fellow-members, for giving. me the opportunity of meeting you this evening. My esteemed friend, President Smith, has requested me to do a bit of "reminiscing" as to the earlier years of my career as a mining engineer, which has now covered a period of fifty years. Let me reassure you by promising that my narrative will not include all the experiences I have had over that long period. You will, I trust, pardon what might seem egotistical but I do not see how a personal narrative could well be otherwise.

Jan 1, 1928

By R. P. Rothwell

AT this our first meeting I beg to call the attention of the members of our Institute to what is certainly a question of the greatest possible importance to the industries we represent; and more particularly to the welfare of the coal and iron trades: I refer to the enormous waste of coal in mining and in its preparation for market, as now practised in our anthracite coal-fields. I t is a fact which many of you can certify to, that we are wasting fully me-half of all the coal in the veins we are now working, and there are cases, which might be mentioned where this proportion, immense as it is, has been greatly exceeded. The popular belief that our deposits of anthracite coal are "practically inexhaustible," is very far from being founded on facts. On the contrary, supposing the present rate of increase in the production to be maintained, it is probable that a maximum yield for our coal-fields would be attained in about fifteen years ; there are in fact some of our smaller basins where the principal veins are nearly exhausted and the production has already attained its maximum. There are others, again, where the depth attained-and it must be borne in mind that we commenced working at the surface outcrop moderate though it is (scarcely ever reaching eight hundred feet), has so increased the cost of mining as to imperil the capital invested, and though it requires but little foresight to predict the time when the difficulties of mining will be very considerably increased by reason of the greater depth, greater quantity of water, fire-damp, and other fruitful sources of cost, yet, ignoring these recognized facts, we continue to waste more than one-half of the coal where it is obtained with the least danger, expense, and trouble, that is, near the surface-either above water-level or at a moderate depth . below it. The inspection of almost any accurate mine map will satisfy you that, on an average, we leave fully one-third. of the coal in the ground as pillars to support the roof; in some places more than one-third thus remains, while it is very rare that less than one quarter is left. In almost every case this coal is absolutely lost, for it will very rarely pay to reopen gangways and lay roads to it after that portion of the mine has been abandoned. Is it necessary in all cases to support the roof, and where it is, may not some artificial

By W. J. Keep

Almost without exception, writers on the subject say that sulphur in cast-iron will cause it to be white, and is in every way injurious. All founders believe that a small amount of sulphur in the fuel will work great damage, and that if any castings crack, or if anything out of the general run occurs, it may be charged to sulphur in the fuel. Fuel rarely contains more than 1 per cent. of sulphur, and if this can produce so marked an effect, one would suppose it an easy matter to introduce sulphur into cast-iron, so as to produce castings containing different desired percentages of sulphur. We have be-

Jan 1, 1894

By D. R. Parrish, K. W. Beaver, H. W. Wood, R. W. Rausch

A pilot test of forward combustion in the Shannon pool, Salt Creek field, Wyo., is described. The Shannon sand, 950-ft deep, contains a heavy (25" API), viscous (76 cp) oil. Natural reservoir energy is limited. Primary production, intermittent since 1889, recovered only about 2 per cent of the oil in place. The field is operated by Pan American Petroleum Corp. for the Midwest Oil Corp., the owner. The original pilot was a 1.32-acre five-spot. The expanded pilot has eight producing wells surrounding a roughly triangular area of about five acres with the injection well near the center. A control or comparison well was also recompleted in another part of the field. Operation of the pilot has been little different front an ordinary gas drive. Little special equipment was found to be absolutely necessary. Except for some use of a temperature-resistant cement, all wells were conventionally completed. In spite of poor oxygen consumption, the over-all performance of the pilot has been good. Total oil recovery to June 1, 1961, was 73,971 bbl. The wells of the original pilot alone had produced about 24,000 bbl, equivalent to 50 per cent of the oil in place, when fire breakthrough at the first well occurred. These wells have now produced oil equivalent to more than 74 per cent of the oil in place in the original pilot area and production is continuing. It appears that ultimate recovery will approach theoretical maximums before the wells must be abandoned. Performance of the pilot has been encouraging, and expansion to a fieldwide combustion operation is being investigated. INTRODUCTION The results of both laboratory investigations and field tests of underground combustion have been reported previously.' However, most of the field tests were primarily experimental. More information and experience are needed before forward-combustion operations can be engineered with confidence. The purpose of this paper is to present the results of a successful pilot test of forward combustion. These re- sults should increase confidence in forward combustion as a practical method for commercial oil recovery. HISTORY OF THE SHANNON POOL The Shannon pool is located on the north end of the Salt Creek field in Natrona County, Wyo. It is approximately 50-miles north of the city of Casper. The Shannon pool's3 discovery well was completed in 1889, making this one of the oldest oil fields in the Rocky Mountain region. Three more wells were drilled in 1890. First production was hauled in wooden barrels by horse and wagon to the railroad in Casper. In 1894 a small refinery, the first in Wyoming, was built in Casper to process the Shannon crude. In the following years the field changed hands several times. It appears that each new owner did some development drilling as several wells were completed in each of the years 1895, 1902, 1905 and 1912, with negligible development in the intervening years. Forty-eight wells were drilled in this period, but many were later abandoned. Discovery of the more prolific Salt Creek field proper ultimately forced suspension of operations at the Shannon pool. After 1915 there was only sporadic production, mostly to supply cheap boiler fuel to drilling rigs in the Salt Creek field. But even this was discontinued in 1931. Since then the pool had been dormant until the recent operations, which are the subject of this paper. The Shannon pool is now owned by the Midwest Oil Corp. Field operations are conducted for Midwest by Pan American Petroleum Corp. THE RESERVOIR Fig. 1 is a map showing subsurface contours of the Shannon pool. The reservoir is on a nose of the Salt Creek anticline dipping to the north at about 500 ft/mile. The trap is provided by a shallow fault on the updip side of the productive area. The downdip limits are bounded by water, but this water has not provided an effective source of reservoir energy. The Shannon sand outcrops at many places in the immediate vicinity, providing good surface indications of the Salt Creek anticline. At the Shannon pool the sand has been lowered by faulting and is overlain by about 900 ft of shale and other sands. The Shannon sand consists of two members. The upper, a water sand, is about 40-ft thick and is separated from the lower member by several feet of sandy shale. The oil pay occurs in the lower mem-

By Thomas M. Drown

ZING is, as is well known, very brittle at a temperature of about 210' C. (410' F.), and may then be readily pulverized in a mortar. By sifting it may be obtained of uniform grain. I have been accustomed to prepare products passing through 40, 60, and 80-mesh sieves, and also by bolting through a fine handkerchief. The principal analytical uses to which I have hitherto applied this material are to the reduction of iron directly from the ore by heating it with the pulverized zinc, and the reduction of ferric to ferrous compounds in solution. In the first case the pulverized ore, 0.5 gram or less, is intimately mixed with about ten times its weight of the pulverized zinc (the finer the zinc the better), in a porcelain crucible, and this mixture is covered with about the same amount of zinc. The crncible is then heated at the top of the flame of a Bunsen bhrner, at a dull red heat, for about ten minutes. The crucible should not be covered. When cool, the crucible, with its contents, is placed in a flask treated with hot dilute sulphuric acid, and brought quickly to a boil. The zinc and reduced iron are dissolved in a few minutes and the flask is then tightly corked and allowed to cool. When cool, the iron is directly titrated by potassium permanganate.

Jan 1, 1879

By Edwin Ludlow

To THE members of the American Institute of Mining and? Metallurgical Engineers who were fortunate enough to be able to attend the Fiftieth Anniversary at Wilkes-Barre, it was brought home that commercial anthracite requires not only expensive mining but that the milling or preparation of it is also a costly operation, requiring very large capital expenditures and high maintenance and labor costs. The great trouble that coal men meet in discussions of coal problems today is the difficulty the average coal user, especially in the East, finds in distinguishing between anthracite and bituminous coals. They are two entirely separate problems and yet the people who are burning coal complain bitterly of the high cost of anthracite and quote the figures furnished in regard to the prices of bituminous coal and feel that the anthracite operators are making an excessive profit, without realizing the enormous difference in the cost of production in the two fields. The great difference that can be marked is that in this year of industrial depression the prices of anthracite have been not only maintained but have increased during the summer, while the price of bituminous coal has been continually dropping since the first of the year, and yet the same law of supply and demand governs both anthracite and bituminous. In order to understand the situation the two problems must be considered from their separate points of view.

Jan 1, 1921

By J. Fageant, W. C. Ellis

All major regions in a progressively solidified germanium ingot were related through successive orders of octahedral twinning. The occurrence of lineage structure and the generation and survival of orientations are discussed. WHEN metals solidify in a temperature gradient a preferred orientation, or casting texture, usually develops. For example, in face-centered and body-centered cubic metals, most of the solidifying crystals have a cube axis, <loo>, aligned approximately in the freezing direction.&apos; In the solidification of diamond cubic metals this is not the case, since there is a natural tendency to form twin orientations.&apos; . In this paper, twinning relationships in cast germanium are described; some conclusions with respect to nucleation and survival of new orientations are discussed. In the first experiment, an ingot of high purity germanium, % in. in diameter and 1 % in. in length, was formed by progressive solidification4 from the bottom. The ingot was cut into 21 slices, each circular and about 0.030 in. thick. The top surface of each slice was polished and etched to reveal the regions of different orientations. Orientations were determined by the Laue X-ray back-reflection method. The uncertainty in the determined orientation relationships was l" or 2" when separate slices and films were involved. Frequently, however, advantage was taken of illuminating across a boundary when the patterns of the two orientations were recorded on the same film. The uncertainty then was less than 1". Often the twin relation was evident from common zones or individual reflections. Twin relationships were recognized through comparison of the values of the nine angles between cube poles of the two orientations with those calculated for successive orders of octahedral twinning. The birth and survival of each region can be reconstructed by visual examination of the etched slices shown in Fig. 1. In slice 21, where solidification began, many regions are present; these regions were found to be twin-related. Solidification appears to have started from one nucleus formed probably at the wall of the crucible.* Subsequent ori- entations were developed by nucleation on existing solid surfaces, and only in the twin relationship. This is an example of a general process of nucleation on a surface of existing solid and may be descriptively termed oriented nuc1eation.t In germanium, and other diamond cubic substances, the orienting habit is that of twinning on an octahedral plane.&apos; " The prevalence of straight traces in the polished surfaces of succeeding slices (Fig. 1) suggests that the twinning observed in the first slice persisted throughout solidification. This was confirmed by X-ray determinations. The schematic diagram of Fig. 2 shows the twinning relationships of the major regions throughout the ingot. Since all observed relationships are describable as twinning, it is reasonable to conclude that no random nucleation occurred in the freezing of the ingot. An alternative possibility would be that nucleation of a random nature occurred, but only those nuclei in twin orientations survived in subsequent growth. This is unlikely for there would be as good a reason for the growth of randomly oriented nuclei as for the growth of the many different orientations present after several orders of twinning. The many twin components contain a wide distribution of orientations, and did grow. In fact, they are the only ones found in the solid. The conditions of solidification of this ingot were such as to discourage nucleation of crystals wholly in the liquid. The rate of solidification was 0.125 in. per min. This slow rate of heat removal afforded but small opportunity for supercooling within the liquid —a condition needed to provide enough decrease in free energy for such nucleation. When nucleation occurs on an existing solid surface, the interfacial energy between the existing and forming regions is important in determining the new stable orientation. The new orientation is expected to be one which minimizes this energy. In the diamond cubic structure, the interface for the

Jan 1, 1955

By G. L. Coleman, D. S. Hutton, W. C. Leslie

The occurrence of twins in a iron, generated during cooling through the ?-a transformation, is well established,1-8 but this phenomenon has been nearly ignored during the past 20 years. It is the purpose of this note to call attention to the prevalence of such twins and to illustrate their appearance. The work of paxton7 and Kelly8 has demonstrated beyond reasonable doubt that for Neumann bands (mechanical twins) in a iron the twinning plane is (112) and the twinning direction <III>. The agreement with McKeehan&apos;s earlier work4 on transformation twins indicates that both types of twins in ferrite follow the same twinning law. There is little doubt of this conclusion, but it could be strengthened by a microbeam X-ray determination of the orientation relationship between a single ferrite grain and a transformation twin within that grain, as in the technique used by Kelly8 on Neumann bands. RESULTS AND DISCUSSION Transformation twins, identified by their appearance on a polished and etched section, were found in

Jan 1, 1960

By N. B. Aughenbaugh, W. C. Patrick

The availability of a thorough, simple-to-use roof fall classification system is desirable for several reasons. First, such a system would expedite the reporting of falls for the purposes of estimating material removal costs, analyzing damage levels, and complying with federal regulations to report falls in certain areas of the mine. Second, the classification system would allow the mining engineer to record falls routinely with little time and effort expended. This would encourage him to make observations concerning what type of roof support would work best in a given situation. Third, and probably most important, an

Jan 3, 1979

By W. G. Oldham

By monitoring the capacitance of abrupt p-n junctions it is possible to follow the motion of substitu-tional impurities. A p-n junction is formed by growth of silicon from an Al-Si alloy on an n-type silicon sutstrate at a temperature in the range 650" to 750°C. The diodes are etched and sorted for consistent V-I and capacitance behavior and separated into groups. After irradiation, each set with an unirradiated control set is annealed to various temperatltres for 10 mm and the capacitance remeasnred. For very heavily doped diodes (-1019 per cm3) observable capacitance changes occur at neutron fluences of >1015 per cm 3. The results may be interpreted in seceral ways, the simplest of which is to assume simple vacancy diffiision with small impurity -racancy interaction (at the diffiision, i.e. annealing temperature of 700°C). In this interpretation it is found that a typical vacancy makes about 1024 jumps and travels about 10-5 cm before disappearing. The required effective annihilation center density is about 1016per cm3 . Estimates of the vacancy-impurity interaction can be made and the above numbers correctecl, but for arty reasonable assumptions the number of vacancy sinks connot be much reduced. ThE complete annealing of radiation induced defects requires that the vacancies and interstitials either recombine, travel to the surface of the crystal, or travel to an annihilation center, e.g., a dislocation or a precipitate. If the interstitial is ignored except as a possible vacancy annihilation center at low temperatures,* the motion of vacancies may be followed by monitoring the corresponding motion of substitutional impurities. pfister2 has measured the enhanced diffusion of impurities in an asymmetric shallow diffused silicon structure by optically monitoring the junction movement. In these experiments we monitor instead the capacitance of a heavily-doped deep symmetric p-n junction. The sensitivity for this method is several orders of magnitude higher than in Pfister&apos;s technique, mainly for two reasons: 1) the junction capacitance of a heavily-doped junction is sensitive to impurity movements in the Angstrom range* com- and 2) the junction may be far from the surface which is a major annihilation center for vacancies. THE EXPERIMENT A p-n junction is formed by the epitaxial growth of silicon from an A1-Si alloy on a silicon substrate at a temperature in the range 650° to 750°C. The technique used is the transport of an aluminum melt through a temperature gradient.4 A 10-mil thick aluminum disc is sandwiched between two silicon wafers and the assembly raised to about 650° C with a temperature gradient normal to the sandwich. After about 8 hr the upper (hotter) wafer has been entirely transported and deposited epitaxially on the substrate wafer. The substrate and overgrowth resistivity are measured with a 4-point probe. The as-grown structure is lapped until the wafer is about 1/2 mm thick with the junction in the center. Contacts consisting of electroless nickel covered by electroplated rhodium are applied to both the p and n sides. The wafer is diced into square dice 1/2 to 1 mm on a side and the dice are etched sufficiently to remove approximately 1 mil of silicon. The following results are all for aluminum (p-side) and antimony (n-side) doped specimens with NA =3x 1018 per cm3, ND = 2-8 x 101A per cm3. The diodes are sorted for consistent V-I and capacitance behavior and separated into groups. After irradiation, each set with an unirradiated control set is annealed and the capacitance remeasured. A special capacitance measurement method is used to insure a low sensitivity to shunt resistance. The diode is voltage driven and the current monitored by a phase lock amplifier. It is possible to adjust the detector phase to a point where shunt resistances as low as 100 O have no effect on the reading. The diodes in this study have a capacitance in the range 1000 to 5000 picofarads and a shunt resistance in the range 100 to l06 O depending on the stage of the anneal. THEORY The theoretical problem is twofold: 1) The computation of the amount of impurity diffusion and hence the impurity profile resulting from a given amount of vacancy motion, and 2) the computation of the capacitance from the impurity profile. A comparison of the theoretical and experimental capacitance (in particular the changes) yields the amount of vacancy motion. Vacancy Motion. A convenient parameter to measure the total amount of vacancy motion is Jv the total number of vacancy jumps per unit volume. Although this parameter varies with position in the crystal, owing to vacancy annihilation at the surfaces, it is approximately independent of position far from the surfaces, i.e. in the junction region. In terms of the number of vacancies per unit volume Nv and the vacancy diffusivity given by

Jan 1, 1970

By C. S. Smith

The partial persistence of grain size and grain shape on melting and resolidifying crystalline substances, as well as the general effects of pre-solidifi-cation and of superheating on nuclea-tion rate, have been attributed to the presence in the liquid of crystalline impurities bearing some structural relation to the principal solid and hence capable of serving as nuclei for its crystallization. That such lattice matching does sometimes occur is well established, but it is surely improbable that a compound possessing both high-temperature stability and the requisite structural similarity should be naturally available in almost every system. It is now suggested that a mechanism for producing appropriate nuclei exists in the crystallization of all but absolutely pure substances. Impurities can he of many kinds. Some will give rise to compounds that are less soluble in the solid crystal than in the liquid. A . crystal forming from a melt or solution containing these will be supersaturated in some degree, and the foreign atoms will commence to segregate during or after solidification. They do not necessarily form pure, unstrained, crystals of the precipitating compound with its normal composition and structure. Generally—at least in the metallurgical examples that have been most studied —the first recognizable nuclei have lattice coherency with the surrounding matrix and have practically the same crystal structure and lattice spacing as the material in which they form, differ- ing only in composition. An extremely thin oxide layer formed under appropriate conditions on or in a solid metal will tend to be coherent with the metal lattice, and the first few atom layers of the oxide in contact with the metal will differ in both composition and structure from massive crystalliue oxide. It will resemble the metal more closely than the oxide. If it did not subsequently change on melting, such an oxide film would constitute an almost perfect "template" or two-dimensional matrix to hold a few atoms of the primary metal in the exact array needed to form a nucleus for solidification. Any precipitating material will adopt the correct spacing over a few atom diameters, and with appropriate substitution of other atoms of the correct sizes a precipitate can match the parent lattice over large areas of cohererlce without excessive strain. In metals, the componentsof a host of oxides, silicides, borides, nitrides, carbides, sulphides, and other compounds are always present in minute amounts. Some of these will be eliminated because of extreme insolubility in the liquid, while others will remain soluble in the solid; occasionally, however, particles will be formed in the solid by coherent precipitation—not of pure substances, but of whatever assortment of atoms best satisfies the joint requirements of availability, affinity, and appropriate average atom size. Of these, many will disappear on melting, but a few will persist unmelted as little rafts of complex composition, maintaining in the liquid a surface of the exact geometry needed to nucleate the solid on subsequent cooling. Their number and size distribution will determine the resulting grain size; the dimensions of the largest will determine the degree of undercooling that can occur before solidification commences. A similar process may operate in the case of phase transformations in solids. The coherent precipitation of supersaturated minor constituents in a low-temperature phase should facilitate the nucleation of this phase on subsequent cooling after transforming into another phase at higher temperatures. At first sight this hypothesis may seem little different from the older ones. It should therefore be emphasized that it does not depend on chance to provide the right compound to form a nucleus, but postulates that every crystal, containing minute amourlts of any of a wide range of impurities, automatically engenders particles having the correct surface structure to serve as nuclei for subsequent solidification. It could operate in any system, metallic, organic, or inorganic. The suggested mechanism is closely analogous to the production of antibodies from antigens in living organisms—indeed, it was a description of the matrix theory of this process that suggested to the writer its crystalline analogue.

Jan 1, 1950

By Jon Kogut

This paper describes three programs, currently in use within MSHA, for graphic analysis of accident frequency data. The first program, TREND, plots confidence bands for curved trends in data compiled over a period of time. In addition to detecting statistically significant upward or downward trends, the program can be used to determine whether an observation at a particular time deviates significantly from the historical pattern. The second program, POIPORP, plots interval estimates for the risk of accident in each of several environments, given an observed number of incidents and exposure time at each environment. POIPORP is designed to quantify the uncertainty implicit in incidence rates based on limited information and to facilitate statistically valid comparisons among the rates. The third program, CINDY, plots dynamically adaptive control charts for accident or injury experience at a given location. These charts are used to detect statistically significant departures from a changing standard or a previously established trend. All three programs are written in FORTRAN IV, utilizing DISSPLA and IMSL. They exemplify forms of statistical analysis that would not be practical without a computer. Use of the programs is illustrated with applications to coal mine fatality and injury experience.

Jan 1, 1983

By W. H. Nielson, L. S. Diaz

Several techniques are presented to adjust small errors inherent in data collected from material balance measurements on the flotation process. The basic technique used is a Lagrange multiplier adjustment of the filtered data taken from the equipment measurements. The raw data are adjusted such that material balances are closed. The adjustments to each data point is inversely proportional to the square of the standard error of measurement. Problem areas in equipment utilization are discussed. Typical results from on-line measurements are presented. This technique can be applied to either on-line process measurements or metallurgical test data.

Jan 1, 1973

By C. S. Barrett

It has been observed that deformation in iron takes place by slip on (110) + {112) + (123) planesl, 2, but in silicon ferrite with low deformation temperatures or high silicon contents (exceeding 4 per cent) the authors have found that slip is confined wholly to (110) planes, at least with small amounts of deformation. The purpose of the present investigation was to determine the effect of this alteration of slip mechanism on preferred orientations in cold-rolled and recrystallized strips. Incidental observations on the effect of the recrystallization temperature were also made. The numerous determinations of the texture of cold-rolled iron and steel have been in satisfactory agreement as to the principal features of the texture (with the exception of a few conclusions that apparently have been based on insufficient data). The texture is chiefly one in which 11101 directions of the grains lie along the direction of rolling, with a deviation of a few degrees, and in which the (100) planes lie in the plane of the rolled sheet, with a deviation from this position chiefly about the rolling direction as an axis. This deviation about the rolling direction as an axis has been measured by different observers and lies between about 45" and 50" or 60" for iron5, 6, 9 and is usually in the neighborhood of 50" for mild stee16, 7, 8. The range of this deviation is a function of the percentage of total reduction8, 10. Post8 reported that it decreases with increasing percentage reduction, but apparently he studied only the surface material, which Gensamer and Meh17 found to be somewhat differently oriented from the material in the inside of the sheet. McLachlan and Davey10 found that the deviation also decreases with increasing percentage of total reduction for the material in the interior of the sheet and is independent of the percentage of reduction per pass. The deviation about the cross direction as an axis (the direction in the

Jan 1, 1937

By R. F. Hollis, C. K. McArthur

PRIOR to the application of anion exchange, all recovery of uranium from acid leach liquors precipitated an impure product requiring further upgrading before it could be refined. The ion exchange process, on the other hand, provides excellent selectivity for extracting soluble uranium from leach liquors, so that high grade concentrates can be produced directly. The discovery that uranium is readily adsorbed by anion exchange resins, together with the experience of resin and equipment manufacturers in water treatment, led to rapid development of ion exchange in a multiple column operation. Many processing plants using fixed bed ion exchange are in operation or under construction in Africa, Australia, and Canada. There are a limited number in the U. S. Although the fixed bed process has been highly successful, the feed to the ion exchange columns must be a clear solution, which is obtained by filtration or by countercurrent decantation of leached pulps. With some ores, poor filtration or settling characteristics make production of a clear solution difficult. Most processing plants in the U. S. receive their ores from a number of small mines, and there is considerable variation in the settling and filtering behavior of the ores. An ion exchange process was therefore desirable in which the uranium could be recovered directly for the leached pulp by adding ion exchange resin, which could be then separated from the pulp by a screening operation. The process would thus resemble the cyanide-charcoal process in which gold is adsorbed from cyanide pulp by means of activated charcoal. Preliminary tests in which leached pulps were directly contacted with resin beads led to the development of the RIP process.

Jan 4, 1957

By Thomas T. Read

It is natural, in reviewing the progress that has been made in mineral industry education during the three quarters of a century that has elapsed since the American Institute of Mining Engineers was organized in 1871, to seek to establish some significant correlation. Earnest endeavor along such lines, however, produces nothing more in the way of fundamental relationship than a technical economic interest in mineral production and utilization in the United States, which had been steadily increasing since 1800. This is a sound correlation, since it is unquestionable that organized and systematic mineral industry education had its origin in Germany, more than 150 years before 1871, in an economic interest in producing minerals for use with the maximum of recovery at a minimum of cost. Mineral industry became the originator* and creator of systematic technical education because of the political and economic fact that in all European (and most other) countries, prior to 1800, precious metals belonged to the ruling power, no matter upon whose land they were discovered. The practical way of working under this system was to grant to a discoverer the right to work the deposit on payment

Jan 1, 1947