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By J. R. Campbell

It is the purpose of this paper to review somewhat in detail the literature on the subject that is extant, which ought to provoke considerable beneficial discussion. The value of 1 per cent. ash in blast-furnace practice was brought to the attention of the writer when he was connected with the U. S. Steel Corpn. Various groups of blast furnaces in the Pittsburgh district compiled a statement in which the average saving was about 6 c. per ton on pig iron for every 1 per cent. of ash reduction. Later, the same groups of furnaces, when materials had reached a higher price, compiled a statement in which there was a 30-cent saving on pig iron for every 4 per cent. ash reduction in the Pittsburgh district, which was equivalent to 7½ c. for every 1 per cent. ash reduction. In the Chicago district, on long freight hauls of coal and coke from the Pocahontas district, the set-up was 30 c. per ton of pig iron for every 2 per cent. ash reduction, or 15 c. for every 1 per cent. Some years ago, Ralph H. Sweetser, of the American Rolling Mill Co., presented a paper which provoked considerable comment.' To get the matter again before this body a résumé of his computations is given below: Comparison of Pig Iron Costs Ash in Coal. Ash in CoKe, Fixed Carbon in Coke peR Ton OB PIG Iron peN Day, Per Cent. PeR CeNt. Coke. Per Cent. PIG IRon. Lb. Tons 6.00 8.70 89.80 1800 365.0 7.00 10.15 88.35 1860 353.2 Coke with 8.70 Per Cent. Ash Ore mixture, 4144 It). = 1.85 tons @ $5.50.............................. $10.17 Coke, 1800 lb. = 0.90 ton @ $6.50..................................... 5.85 Limestone, 1000 lb. = 0.50 ton @ $1.50................................. 0.75 Labor, $365 per day on 365 tons....................................... 1.00 Supplies and service, $250 per day...................................... 0.68 Overhead, $200 per day............................................... 0.55 Reserve for relining and depreciation................................... 1.00 Total............................................................. $20.00

Jan 1, 1931

By G. W. Toop

In a recent publication,31 Darken has derived an equation to describe thermodynamic behavior in ternary metallic solutions with compositions near pure component 1: Eq. [I] is understood to be a general equation, consistent with the ternary Gibbs-Duhem equation, which is proposed as a logical formalism in view of observed behavior in some binary metallic solutions31'32 rich In Eq. and am are constants obtainable from the 1-2 and 1-3 binaries. The parameter 023 may be determined from measurements on the ternary The purpose of this discussion is to compare Eq. [I) or [3] with other ternary formulations involving binary terms, within the regions of validity of Eqs. [I], [2], and [3]. First, the ternary point is considered to be at the intersection of two composition paths, one with constant N1 and another with constant N2/N3 as shown in Fig. 10. The terms in Eq. [3] may be related to the binary points shown by multiplying the first term on the right-hand side of Eq. [3] by N2 (1) /l -N1, the second term by the third term by and the fourth term by each multiplier being unity: It should be noted here that no suggestion has been made that either the binary or the ternary systems form regular solutions. However, Eq. [5] and hence Eq. [3] shows that the contribution made to the ternary excess free energy from the 1-2 and 1-3 binaries has the same form as for a regular ternary system.1 Before considering the term a23 for the above case, a second geometrical relationship is examined with the ternary point at the intersect ion of three composition paths with constant N1/N2, N2/N3, and Nl/N3, respectively, as shown in Fig. 11. For this geometry, ternary values of NZ and N3 in terms of the binary values shown may be substituted into Eq. [I]. Then by making use of identities of the form Eq. [6] contains terms that are similar to those in a ternary regular solution formulation34 based on the geometry shown in Fig. 11. Although at finite concentrations, unless the 1-2 and 1-3 binaries form

Jan 1, 1968

By M. E. Fine

IN the apparatus for measuring internal friction shown in fig. 1, a modification of that described by Kê,1,2 the parasitic energy loss or background is equivalent to a Q-1 of approximately 4x10-5. This low value of background was obtained by using a jeweler's collet of appropriate size for the upper support, eliminating lateral motion without immersing the bob in oil, and designing the bob to reduce air resistance. The pendulum is supported on the frame through a snug fitting, sliding rotary joint (fig. I-B). A slight twist of the top imparts essentially pure torsional motion to the pendulum. No evidence of energy loss in the sliding joint has been observed. In the bob (E) steel balls are used in the torsion arm, and the bottom is filled with lead giving a total weight of 94 g. A lighter bob may be used for small diameter specimens. Another bob was a solid disc with provision for adding discs to change the frequency. The oscillating image of the filament is recorded on a revolving drum camera (fig. 1-3) driven by a synchronous motor. This allows use of frequencies higher than can be measured visually on a glass scale. Samples varying in diameter from 0.020 to 0.075 in. have been measured, the frequencies have ranged from 1 to 12 cps, and the maximum strain varied from 0.5 to 10x10-5. With appropriate modification the sample may be placed in a thermostat. The apparatus may also be used to measure the shear modulus. In the examples of measurement given in table I the internal friction of Permendur and the 46.8 Ni-Fe alloy are due, for the most part, to magneto-mechanical hysteresis8 (elastic hysteresis accompanying stress-induced magnetostriction) which depends on strain amplitude and increases with annealing. The internal friction of most materials decreases with annealing. References IT. S. K6: Physics Review (1947) 71, 533. 2 T. S. Kê: Transactions AIME (1948) 176, 448; Metals Technology (June 1948) TP 23703. 3 R. Becker and W. Döring: Ferromagnetismus. 365 (1939). J. Springer.

Jan 1, 1951

By G. Donald Emigh

Nothing is more important to life-plant and animal-than phosphate. Its compounds are essential to the energy functions of all living systems and for the formation of bones and teeth. Animals get their phosphate from eating plants and other animals, or domestically from feed supplements. Plants get their phosphates from the soil. Man's most important use of phosphate is for fertilizer; approximately 95% of the world's phosphate rock production is consumed by fertilizers. Most of the balance is processed in electric furnaces into elemental phosphorus, the important raw material for making industrial phosphates. Recovery of uranium from phosphates has been possible but not widely used. However, recent significant developments have generated interest in such recovery in the US and elsewhere. Phosphate occurs in all igneous and sedimentary rocks, and in all fresh and salt water. However, economical recovery is limited to deposits where natural concentration of the phosphate mineral has occurred. Occasionally natural concentration is great enough that the material can be used as mined; generally, however, the ore is low grade_ and must be concentrated. Phosphate rock is produced in 31 countries. Fig. 1 shows the location of major phosphate rock producers as well as some of the known phosphate deposits not yet in production. In the last decade the world phosphate industry has experienced steady growth. World production rose from 98 Mt of phosphate rock in 1973 to 140 Mt in 1982. Fig. 2 shows the growth curve of rock production and graphically illustrates the almost straight-line rise since 1945 in both US and world production. Table 1 gives the breakdown, by countries, of world rock production, 1974 through 1979. Table 2 shows US rock production by producing areas. Definitions of Terms Used in the Phosphate Industry Phosphate Rock: Commonly called rock in sedimentary deposits and apatite in igneous deposits. Those expressions generally include any mined, or mined and beneficiated, fluorine-containing calcium phosphate used as the raw material for the next stage of manufacturing. The average phosphate content in rocks is 0.1 to 0.2% P2O5, as documented by McKelvey (1973). About 200 minerals contain more than 1 % P2O5. However, the important mineral in igneous rocks is fluorapatite, [Ca5 (PO4),3 F], containing about 42% P205 and 3.8% F2; in sedimentary rocks the important mineral is francolite, a carbonate fluorapatite containing up to 2% molecular CO2. Both are in the apatite family of minerals. Most phosphate rock, whether beneficiated or not, is a fine-grained material. The expression phosphate rock has no relation to its phosphate content. For example, phosphate rock from Idaho used in the production of phosphorus may contain about 24% P205, whereas rock from Morocco may contain 36.6% P2O5. Phosphorite: A deposit of phosphate directly or indirectly of sedimentary origin, which is of economic interest. Grade of Phosphate Rock: The calcium phosphate content of phosphate rock is expressed in different world areas by one of the following terms: BPL (bone phosphate of lime) TPL (triphosphate of lime) P2O5 (phosphorus pentoxide) P (phosphorus-not commonly used) An illustration of relationship is: 80% BPL = 80% TPL = 36.6% P5O2 = 16% P

Jan 1, 1983

By J. E. Campbell, G. D. Calkins, N. M. Ewbank, M. Pobereskin, A. Wesner

GRINDING for size reduction affects the economics of many processes and products. It is essential as the first step in many industrial processes and is also a finishing step for materials with properties depending on particle size, such as talc, cement, and silica sand. Intermediate and fine grinding are vital operations in the U. S. cement industry, which is producing more than 250 million bbl of cement per year.' Wear of the grinding media is a large part of the grinding operation cost. Problems encountered in grinding cement are so complex that evaluation of efficiency and economy of grinding media is difficult.2 It has been especially difficult to evaluate the relative effectiveness of different types of balls because there are no good testing techniques. Many other industrial operations can be evaluated on a laboratory scale with reasonable accuracy. This does not hold true for evaluation of grinding balls. The consistent results obtained in a laboratory test under a given set of conditions are not always borne out in field application. Rough evaluations of the effectiveness of various compositions and types of grinding balls have been made in the field by using a full charge of one type in a mill and comparing the production record with another run using another type of ball. This method is time-consuming and not very precise, as the second run may not have been carried out under identical conditions. Laboratory-scale tests, on the other hand, have yielded inconclusive results, and many investigators have turned their attention to the development of a field testing technique. Field testing small sample lots of grinding balls has been impractical because it is difficult to identify and recover the test specimens from the grinding mill, and individual groups of balls that have undergone different heat treatments can not be separated.".4 To overcome these difficulties, previous investigators have identified the balls by distinctive marks, notches, and drilled holes, but this procedure has three serious drawbacks: 1) Grinding characteristics and quality of the steel balls may be affected. 2) Physical markings may be worn away in the grinding process, especially during a prolonged run. 3) Recovery from the bulk of the charge will be extremely difficult because the markings are hard to see and may be masked by a coating of the product. To circumvent these difficulties, a radioactive-tracer technique was proposed for recovery and separation of steel grinding balls and subsequent evaluation of the various compositions of the balls. The proposed technique involved five basic operations: 1) Thermal-neutron irradiation activation5 of each group of test grinding balls to a different level of specific radioactivity. 2) Addition of groups of radioactive steel-ball specimens into a ball tube mill. 3) Recovery of radioactive steel-ball specimens from the bulk of the mill charge. 4) Separation of the various groups by their specific radioactivity. 5) Evaluation of actual grinding ball wear. Before any physical tests were performed, required neutron irradiation intensity and time were calculated. Probable composition of the steels to be used was ascertained. An examination was made of the radioactive nuclides8 to be formed which would contribute measurably to the radiation level immediately after irradiation and during the test operation. The radioisotopes formed, their types of radiation, and their half lives are listed in Table I. Of these radioisotopes only iron-59 and chromium-51 were significant for the actual wear test. The intensity of radiation that could be detected by a Geiger counter when the test was completed was the basis for the minimum activation level established. The intensity of radiaton that could be safely handled at the beginning of the test was the basis for the maximum activation level, although this was not considered a major problem. Ten groups of grinding balls of various composition and/or surface or heat treatment were to be tested. One group was designated for the minimum irradiation time. The remaining groups were designated for irradiation periods that increased by increments of 33 pct from that of each preceding group. This difference was considered enough for separation and identification of the groups by comparison of specific activity. Potential Hazards: Possible radiation hazards that might be encountered during this experiment were evaluated for the three important phases: 1) the radiation hazard of placing balls and removing them from the mill, 2) contamination of the product cement by radioactive material worn from the balls, and 3) contamination of the steel by the radioactive balls left in the mill. The radiation intensity expected from the whole group of radioactive balls was calculated to be 250 milliroentgen per hr at 1 ft. This meant the balls would require special shielded packaging and warning labels on the shipping containers. In a radiation field of 250 mr per hr a man can work for 1 hr without exceeding maximum permissible weekly exposure. Since the balls could be dumped into the mill in a matter of seconds, relatively little radiation exposure was anticipated at this stage of the operation. If the weight loss in the balls was 7.7 pct per month and the cement feed through the mill was

Jan 1, 1958

By J. L. Fitch, B. G. Hurd

The presence of gypsum in samples subjected to standard core analysis introduces serious errors in the measurement of water saturation and porosity. The magnitude of these errors, depending upon the type of analysis procedure used, has been evaluated experimentally and theoretically. Water-saturated pore volumes determined by vacuum distillation or retort procedures may be too high by as much as 48 per cent of the volume of gypsum present. The maximum error in this value determined by Dean-Stark extraction with toluene is 36 per cent of the gypsum volume. If pore space is measured by a Boyle's law type porosimeter the maximum erorr due to gypsum is 38 per cent of the original gypsum volume present. The conscientious core analyst may eliminate the errors caused by gypsum by either of two methods. He may apply suitable corrections for the water of crystallization removed from gypsum, or take special precautions to prevent dehydration of gypsum during core cleaning and alzalysis procedures. These alternatives are discussed and methods for obtaining reliable core analysis data are proposed. Gypsum (CaSO4 . 2H2O) occurs as a common mineral in many of the world's sedimentary basins. In addition to its presence as primary bedded evaporitic deposits, it is often found as secondary replacement zones and pore-fillings in host rocks. That it may cause false indications in porosity, both on neutron logs and in standard core analysis, has been generally recognized. False porosity interpretations from neutron logs result because the chemically bound water in gypsum attenuates neutrons as effectively as free water. Errors in core analysis result when gypsum is dehydrated prior to or during the analysis. Vacuum retort procedures used by many laboratories to determine fluid saturation and porosity effect a complete removal of water of crystallization from gypsum. The crystal water, distilled and collected with free water from the sample, is counted as water-sat11rated pore space. Dehydration of gypsum results in a decrease in volume occupied by calcium sulfate and a corresponding increase in pore volume. Thus, if gypsum is dehydrated by sample cleaning and drying procedures, subsequent porosity measurements with gas expansion or compression instruments will be high. The qualitative effect of gypsum on porosity determinations by retort procedures was discussed in a recent article by Bynum and Koepl3. They concluded that since false porosity was interpreted as being water saturated, determinations of oil content were not affected. Others in the industry, however, have pointed out that porosity values are often used with values of water saturation determined independently, e.g., from electric resistivity logs in making reserve estimates. Values of water saturation calculated from the formation resistivity using the Archie equation, S4= are actually low if values of are high due to gypsum. In this case, false porosity values due to gypsum could cause serious errors in calculations of oil-in-place. This investigation was made to determine quantitatively the effect of gypsum on porosity values determined by different core analysis procedures. EXPERIMENTAL PROCEDURES Dehydration of Gypsum The extent and rate of removal of water of crystallization from gypsum under conditions encountered in core analysis procedures were studied. Taken for the experiments were three types of relatively pure, naturally occurring gypsum, viz. selenite, satin spar and massive gypsum. Although all samples probably contained trace chemical impurities, each type lost the theoretical amount of water upon complete dehydration. An automatic recording thermobalance, similar to one described by Mauer2, was used to obtain dehydration rate data for samples heated in dry air. Water

By P. A. Witherspoon, R. W. Donovan, T. D. Mueller

The use of petroleum-barren aquifers for underground storage has become extremely important to the natural-gas industry. A critical problem in assessing the feasibility of a specific aquifer for such use is the permeability determination of the caprock over the proposed storage project. The approach used here is to conduct both static and dynamic field tests on the aquifer being analyzed. Valuable information on the possibility of communication between the storage aquifer and any other aquifers above can be obtained by measuring hydrostatic water levels and water analyses. Significant differences in such data give evidence of the lack of communication between the intended storage reservoir and other horizons. The dynamic approach requires that one well be pumped in the storage aquifer, and changes in fluid levels recorded in both the aquifer and its caprock. The interpretation of the data from such pumping tests involves the solution of nonsteady radial flow in an infinite aquifer and the influence on such flow of a leaky caprock. A finite-difference model has been used to investigate this problem, and the transient behavior has been solved numerically with a digital computer. It has been found that the pressure transients in the storage aquifer are not affected significantly by moderate caprock leakage. The pressure behavior of the caprock is a much better indicator of the degree of leakage, and generalized solutions for this behavior are included. Field data are presented to demonstrate both the static and dynamic approach. If is concluded that appropriate investigation of the groundwater hydrology in an aquifer-type gas-storage project can provide much valuable information for determining the effectiveness of the caprock to hold gas. INTRODUCTION Underground storage of natural gas in the United States has been developing at a rapid rate over the past few years. In 1955, the total gas-storage capacity was about 1.6 trillion cu ft; by 1961, this figure was almost 3.2 trillion cu ft, an increase of 100 per cent in six years.' This trend un- doubtedly will continue because the economics favor the development of gas storage, as opposed to the construction of new pipelines, to meet the inherent cyclic demand for fuel in the metropolitan areas of this country.' About 15 per cent of the current underground gas storage has been developed in petroleum-barren aquifers, i.e., geological domes or anticlines in which no commercial quantities of oil or gas had been produced prior to the storage operations. The necessity for using barren aquifers outside many metropolitan areas of this country has been due to the lack of depleted oil or gas fields that were near enough and large enough to meet the demands of such consuming areas. Pipeline companies have developed aquifer storage along their transmission lines to meet the fluctuating needs of their complex systems. Considerable thought has also been given to the problem of storing gas in a structureless aquifer, both in this country' and in the Soviet Union outside the city of Leningrad.'," Conditions such as these have led to the development of aquifer gas-storage projects in many parts of the U. S. Most of these developments have centered in the Mid-Continent area, and the greatest amount of activity has been concentrated in Illinois.6 Thus, the use of petroleum-barren aquifers for gas-storage purposes has become extremely important to the natural-gas industry. There are three basic problems in developing aquifer-type storage: (1) finding an adequate geologic structure, (2) finding a suitable storage reservoir within the structure and (3) determining the tightness of the caprock over the intended storage zone. The first two problems can be solved by applying conventional methods of exploration geology, but once these problems are solved, the question arises as to why no oil or gas is present in an otherwise favorable setting. Two situations are possible: (1) an adequate source bed was never present, or (2) a source bed was present but the petroleum seeped away because of a leaky caprock. Determining the tightness of the caprock is one of the most critical problems in assessing the feasibility of a specific aquifer for storage purposes. In attacking this problem, one usually takes cores of the caprock and subjects them to a rigorous investigation. Such core data are desirable, but they only detail the matrix properties and cannot be expected to reveal the gross characteristics of the caprock. Several gas-storage projects in the U. S. have had considerable leakage where

By Walter Craft, John L. Lamont

Adequate hardenability has long been recognized as one of the first requirements for producing desired mechanical properties in a heat-treated steel. Since the introduction of the Jominy end-quench test' and the development of correlative information to expand its use, industry has had an effective measure of hardenability. Prediction and control of the hardenability have been made possible by Grossmann's principle2 for calculating hardenability from chemical composition; and Field's conversiona from depth of half-martensite hardening to Rockwell C hardness has made the relation more quantitative. These developments have facilitated the design of new steels and the control of standard grades to the extent that it has been possible to establish tentative hardenability bands for some of the more commonly used alloy steels.4 As the depth of hardening of the Jominy test specimen is usually measured by Rockwell C hardness, it was considered that it should be possible to predict the hardness by a more direct calculation. It has been found that this can be accomplished by the addition of Rockwell C units proportional to the carbon and alloy content, grain size, and position in the Jominy test specimen. The calculation has been found to be fairly accurate, and because of its additive character is relatively simple to use. In principle the method of calculation is somewhat similar to the expressions developed by Herty, McBride, and Hollen-back,5 Burns, Moore, and Archer,= and Burns and Riege1.l The calculation is started from a base that includes the effects of carbon content and position in the Jominy test speimen. Rockwell C units are added to the base in proportion to the alloy content and grain size. This sum represents the Rockwell C hardness up to the level at which a disproportionate increase of hardness is caused by the formation of martensite, and above this level an increment for martensite hardening is added. The effects of alloys are directly proportional to the amounts present and are independent of each other, the carbon content, and the position in the specimen. Furthermore, the factors for determining the martensite increment are dependcnt only on carbon content and are independent of cooling rate and alloy content. It is this absence of interrelation between the different factors that makes it possible to calculate the hardness and makes the method of calculation consistent with the principle that the character of the hardening reaction is governed primarily by carbon and that alloys exert their effect chiefly through control of the critical cooling rate. The principle of the calculation, and the effects of alloys on the critical cooling rate,

Jan 1, 1947

By John L. Lamont, Walter Craft

Adequate hardenability has long been recognized as one of the first requirements for producing desired mechanical properties in a heat-treated steel. Since the introduction of the Jominy end-quench test' and the development of correlative information to expand its use, industry has had an effective measure of hardenability. Prediction and control of the hardenability have been made possible by Grossmann's principle2 for calculating hardenability from chemical composition; and Field's conversiona from depth of half-martensite hardening to Rockwell C hardness has made the relation more quantitative. These developments have facilitated the design of new steels and the control of standard grades to the extent that it has been possible to establish tentative hardenability bands for some of the more commonly used alloy steels.4 As the depth of hardening of the Jominy test specimen is usually measured by Rockwell C hardness, it was considered that it should be possible to predict the hardness by a more direct calculation. It has been found that this can be accomplished by the addition of Rockwell C units proportional to the carbon and alloy content, grain size, and position in the Jominy test specimen. The calculation has been found to be fairly accurate, and because of its additive character is relatively simple to use. In principle the method of calculation is somewhat similar to the expressions developed by Herty, McBride, and Hollen-back,5 Burns, Moore, and Archer,= and Burns and Riege1.l The calculation is started from a base that includes the effects of carbon content and position in the Jominy test speimen. Rockwell C units are added to the base in proportion to the alloy content and grain size. This sum represents the Rockwell C hardness up to the level at which a disproportionate increase of hardness is caused by the formation of martensite, and above this level an increment for martensite hardening is added. The effects of alloys are directly proportional to the amounts present and are independent of each other, the carbon content, and the position in the specimen. Furthermore, the factors for determining the martensite increment are dependcnt only on carbon content and are independent of cooling rate and alloy content. It is this absence of interrelation between the different factors that makes it possible to calculate the hardness and makes the method of calculation consistent with the principle that the character of the hardening reaction is governed primarily by carbon and that alloys exert their effect chiefly through control of the critical cooling rate. The principle of the calculation, and the effects of alloys on the critical cooling rate,

Jan 1, 1947

By Castle. J. E., J. L. Gillson

In this chapter there is a wide difference in the meaning of some words used for rock and mineral names as defined by scientists and tabulated in the "Glossary of Geology and Related Sciences," published in 1957 by the American Geological Institute, and the meaning as used by the commercial producers of feldspar. It is necessary, therefore, to define these terms giving both the "scientific" and the "practical" definitions. There is no ambiguity about the name feldspar itself. This is a general term for a group of related minerals which are silicates of aluminum, combined with sodium, potassium and calcium. The feldspars are the most abundant minerals of the igneous rocks, and since these rocks make up the largest proportion of the earth's crust by volume (although not of the actual surface area of the continental land masses) the feldspars are the most abundant minerals of all. The igneous rocks themselves are classified on the basis of the variety of the feldspar present. The potash feldspars, which are called orthoclase and microcline, are the dominant minerals of the granites and syenites, and of their fine grained equivalents, the rhyolites and trachites. The plagioclase feldspars form an isomorphic series, of which the sodic endmember is called albite, and the lime endmember, anorthite. The members near the sodic end, albite, oligoclase and andesine are the characteristic feldspars of the granodiorites and diorites, and of their fine grained equivalents, the dacites, and andesites. These feldspars-orthoclase, microcline, albite oligoclase and andesine-are the feldspars used commercially. Labradorite, a member of the plagioclase group, in which the lime exceeds the soda in the chemical composition, is the common feldspar of the gabbros, anorthosites, norites, basalts and other so-called "basic" rocks. Although some attempts have been made to use labradorite as a commercial feldspar, none is now used except as an ornamental stone. The mineral anorthite is very rare. Since the feldspar in most of the common igneous rocks is relatively fine grained, and mixed intimately with other minerals, from which it can be separated cleanly only with difficulty, most masses of the common rocks cannot be used as sources for the feldspar contained in them. It is only the rarer types of rocks in which the feldspar is very coarse-grained, or ones containing very little of the iron-bearing minerals which are objectionable impurities in commercial feldspar, that are quarried to yield an acceptable product. The most widespread type of such a rock from which commercial feldspar can be produced, is that called "pegmatite." These rocks are dikes and bodies of irregular shape and of a size measured in feet or yards in most cases, rather than in miles. They are more commonly associated with granites, rather than with other coarse-grained igneous rocks. Many of them contain crystals of various minerals, including the feldspars, that are much larger than are found in the host rock, the granite, and in many there are large masses of feldspar that are sufficiently free from iron-bearing silicates so that products acceptable to the ceramic industry can be produced, in some cases simply by hand sorting. Most of this feldspar in pegmatites, however, does contain intergrown quartz up to 25 pct. Pegmatites are so important, not only as commercial sources of feldspar, but also of other minerals which are produced com-

Jan 1, 1960

By Brian F. Osborne

A continuous on-line particle-size analysis system for solid/liquid suspensions is described. The basic sensor utilizes a centrifugal principle to separate particles according to size, the resultant separation being measured by means of beta-ray attenuation. Results obtained when analyzing a variety of materials at sizes from 65 mesh (210 µ) to 20 w are discussed in detail. Accuracies better than 2% are demonstrated. The effects of particle specific gravity, and mixtures of materials of diverse specific gravities, are discussed from both a practical and a theoretical viewpoint. It is demonstrated that particle specific gravity has a minimal effect on the size reading obtained. This renders the instrument suitable for handling materials where the ratio of light to heavy component may change. The design of the first commercial installation of this instrument is described in detail. This installation will be capable of analyzing three streams in sequence, measurement at three particle sizes being effected on each stream.

Jan 1, 1975

By Ralph B. Stevens

INTRODUCTION Underground fires continue to be one of the most serious hazards to life and property in the mining industry. Although underground mines are analogous to high-rise buildings where persons are isolated from immediate escape or rescue, application of technology to locate and control fire hazards while still in their controllable state is slow to be implemented in underground mines. Even in large surface structures such as hotels, often only fire protection systems which meet minimal laws are implemented due to the high cost of adding extensive extinguishing systems, isolation barriers, alternate ventilation, escape routes and alarm systems. Incomplete and ineffective protection occasionally is evidenced where costs would not seem to be a factor, such as the $211 million MGM Grand Hotel fire November 21, 19801. Paramount in increasing fire safety and decreasing the threat of serious fire is early warning followed by proper decision analysis to perform the correct action. However, very complex fire situations can be produced in structures such as high-rise buildings and underground mines simply because of the distances between the numerous fire-potential locations and fire safe areas. Other complexities arise when normal activities occur that emit products of combustion signaling a fire condition to a sensitive fire/smoke sensor. For example, the operation of diesel equipment or the performance of regular blasting can produce combustion products that reach the sensitive alarm points of many sensors2. Smoke detectors for surface installations provide fire warning when occupants are at a distant location or when sleeping, thus greatly reducing injuries and property damage. However, when installed in the harsh environments of underground mines, fire and smoke detection equipment soon becomes inoperative, unreliable, or requires excessive maintenance. The U.S. Bureau of Mines has performed many studies and tests to improve fire and smoke protection for underground mine workers3. This paper describes several USBM safety programs which included in-mine testing with mine fire and smoke sensors, telemetry and instrumentation to develop recommendations for improving mine fire safety. It is hoped that the technology developed during these programs can be added to other programs to provide the mining industry with the necessary fire safety facts. By recognizing fire potentials and being provided with cost-effective, proven components that will perform reliably under the poor environmental conditions of mining, mine operators can provide protection for their working life and property equal to that which they provide for themselves and their families at home. The basis of this report is two USBM programs for fire protection in metal and nonmetal mines4,5 and one coal program6. The data was collected beginning in May 1974 and continuing through the present with underground tests of a South African fire system installed at Magma Mine in Superior, Arizona, and a computer-assisted, experimental system at Peabody Coal Mine in Pawnee, Illinois. The conduct of each program was as follows: • Define the problem and its magnitude in the industry • Develop concepts to solve or diminish the problem • Review available hardware or systems approaches to fit the concepts • Install and demonstrate the performance of a prototype system through fire tests in an operating mine. MINE FIRE FACTS Whether in coal or metal and nonmetal mines, the potential severity of fire hazard is directly related to location. As shown in Figure 1, fire in intake air at zones A, B, C or D can cause contamined air to route throughout the mine quickly if not detected, isolated or rerouted. Causes and location of former metal and nonmetal fires are represented in Table 1; the cause and location of fatalities and injuries is shown in Table 2. Coal-related fires and their impact on deaths and injuries are graphed in Figure 2; their locations are described in Table 37. Significantly the table shows that the hazard to personnel was three times greater for fires occurring in shaft or slope areas, and the percentage of deaths and injuries was four times that of other areas. Number of Persons Affected A 129-mine sample indicated that from 8 to 479 employees per shift work in underground metal and nonmetal mines, and that deeper mines have larger populations, as shown in Figure 3. Coal mining relates similar employment, and a 16-state sample of 670 mines employing at least 25 persons shows the distribution in Figure 4. Drift mines accounted for 58 percent of the sample but employ only 45 percent of the underground workers.

Jan 1, 1982

[ARTICLE I. NAME AND OBJECT Section 1. This Society shall be known as the Society of Petroleum Engineers of the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Section 2. The object of the Society of Petroleum Engineers shall be to furnish a medium of cooperation among those interested in the petroleum-natural gas industry an to promote the advancement of this branch of mineral technology through meetings to stimulate the preparation, reading, discussion and circulation of papers connected therewith. ARTICLE II. MEMBERS Section 1. Any person who is a member of AIME may become a member of this Society by the specified process. Section 2. Local organizations may be formed by the Society of Petroleum Engineers as subsidiary units, the membership of which shall be subject to and in accordance with the by-laws of the Institute.]

Jan 1, 1961

By AIME AIME

ON April 7 the twentieth national Open-hearth Conference of the A.I.M.E. will be held in Birming¬ham, Ala., in conjunction with a meeting of the Committee on Blast Furnaces and Raw Materials. At least 300 engineers and operators are expected to attend. Birmingham, the industrial city and iron, and steel center of the South, has been called the "Magic City." Men actively engaged in business in Birmingham today have seen practically every building in the business district erected, have witnessed the establishment of every existing industry, and have hunted birds cm the site now one of the busiest corners of the business district. Incorporated as a town in 1871, the city today has a population of more than 380,000 in its metropolitan area. It is

Jan 1, 1937

By J. E. Schaffer

Drilling activity in Ohio increased slightly in 1939. There were 1020 completions as compared to 910 in 1938. During the past six years the number of completions has varied little (Table 1). Oil production in Ohio has been gradually declining since 1896, when the peak production of 23,941,000 bbl. was reached (Fig. 1). Since that date production has slowly declined to an estimated production in 1939 of 3,144,134 bbl., the lowest in 53 years. This total production is divided approximately into the following grades of crude oil: Pennsylvania, 1,185,456 bbl.; Corning, 1,261,615 Flg 1. bbl.; Lima, 578,500 bbl.; Lodi, Based on figures of U. S. .Bureau of 104,740 bbl.; Cleveland, 13,823 Mines and Oil andGas Journal bbl. Table 2 shows the prices paid for the various grades of crude oil.

Jan 1, 1940

By J. E. Schaffer

Drilling activity in Ohio increased slightly in 1939. There were 1020 completions as compared to 910 in 1938. During the past six years the number of completions has varied little (Table 1). Oil production in Ohio has been gradually declining since 1896, when the peak production of 23,941,000 bbl. was reached (Fig. 1). Since that date production has slowly declined to an estimated production in 1939 of 3,144,134 bbl., the lowest in 53 years. This total production is divided approximately into the following grades of crude oil: Pennsylvania, 1,185,456 bbl.; Corning, 1,261,615 Flg 1. bbl.; Lima, 578,500 bbl.; Lodi, Based on figures of U. S. .Bureau of 104,740 bbl.; Cleveland, 13,823 Mines and Oil andGas Journal bbl. Table 2 shows the prices paid for the various grades of crude oil.

Jan 1, 1940

By H. Larson, J. Chipman

The ferrous and ferric oxide concentrations of slags, expressed as j = Fe+++/(Fe+++ + Fe++), have been established through gas-slag equilibrium at 1550°C in a range of oxygen pressure of 10-I to 10-9 equilibriumatm. The value of j is increased by basic additions (BaO, CaO, MgO, MnO) and decreased by acidic oxides (SiO2 and TiO2). Oxygen pressure is shown graphically as a function of composition for slags which are analogous to those at the slag-gas interface of the open hearth furnace. THE progress which has been made in recent years in understanding the chemistry of metallurgical slags has been based largely on studies of slag-metal and slag-gas equilibria. There is a considerable body of knowledge which is applicable to reactions occurring at the slag-metal interface in open hearth steelmaking. There is little information concerning reactions of the slag with the furnace atmosphere and hence little basis for an understanding of the transfer of oxygen, sulphur, or hydrogen between gas and slag. The oxygen pressure of the open hearth atmosphere is normally of the order of 10-1 to 10-3 atm which differs by several orders of magnitude from that of about 10" atm at the slag-metal interface. The chemical properties of the slag, for example, the ratio of ferric to ferrous iron and the ability of the slag to hold sulphur in solution, are greatly affected by changes in oxygen pressure. This investigation was undertaken to enlarge our knowledge of the effect of oxygen Pressure on steel-making slags. Using air or controlled mixtures of CO a CO2 a range of oxygen Pressures from 10.' to 10.' was covered. Review of the Literature There are only a few references in the literature which pertain directly to this investigation. The most important is that of Darken and Gurry1,2 on the system iron-oxygen. This work included the determination of the phase diagram of the system and also a study of the field of homogeneous melts and their oxygen pressures. Their apparatus and procedure were very similar to that used in this study. Iron oxide was melted in a platinum crucible under an atmosphere of CO2:CO, CO2:H2, H2O, CO2, air or O2 depending upon the partial pressure of oxygen desired. After equilibrium was reached, the sample was quenched and analyzed for ferrous and ferric oxide. By appropriate calculations these authors were able to determine the oxygen and iron activities in the various slags, heats of formation of the oxides of iron, and heats of solution of iron and oxygen in the liquid slags. In a subsequent paper' the same authors made a less thorough investigation of the effects of additions of lime and manganese oxide on the composition of iron oxide melts. Only a few experiments were made and those in a narrower range of temperature and oxygen pressure. Darken' has investigated the fusion temperature of iron oxide in contact with silica under various atmospheres. He found that the temperature changes from 1120° to 1447°C as the gas composition changes from CO2/CO equal to 20.8 to pure oxygen. A comprehensive paper by White" predates the work of Darken and Gurry. The decomposition of ferric oxide into oxygen and lower oxides of iron was studied from 1000° to 1650°C and under oxygen pressures from 2 to 76 cm of mercury. The effect of

Jan 1, 1954

By George L. Atwood, William Brown

Phosphate ore is being mined at Monsanto Co.'s Henry mine, near Soda Springs, Idaho, for the company's three furnace elemental phosphorus plant near Soda Springs. The finished product from the furnaces is elemental phosphorus which is subsequently used in the manufacture of detergents, food preservatives, fire retardants and other consumer items. In stripping and mining, D-9 crawler tractors are utilized to rip and push-load rubber-tired scrapers. The equipment consists of six D-9G crawler tractors, four Caterpillar 657B scrapers, eight Euclid S-24 scrapers, one Reich T750 drill and one Caterpillar No. 16 patrol plus various support equipment. Stripping is performed on a 12- month basis, two shifts per day, whereas mining is mainly in the summer months on a one-shift basis. The hauling season begins May 15 and ends November 1 due to freezing weather and snow conditions. Annual production is 1 million tons of phosphate rock and 2.5-3 million cu yd of stripping. Stripping, mining and hauling is performed for Monsanto by Dravo-Soda Springs, a mining contractor which owns, operates and maintains all equipment used. The contractor is paid for stripping by the bank yard and for ore mined and hauled on a tonnage basis.

Jan 8, 1972

By J. J. Gilman

Examination showed that characteristic cleavage step patterns are observed on the cleavage surfaces of undeformed, slipped, bent, twinned, compressed, and indented zinc crystals; and the effect of temperature is discussed. Dimples were seen to produce cleavage steps in a treelike pattern in otherwise undeformed crystals. The steps seem to originate when cracks intersect screw dislocations. IT has been known for a long time that the path of fracture in polycrystals may be discontinuous (see Jaffe, Reed, and Mannl for review). Recently, Kies, Sullivan, and Irwin2 have proposed, and given evidence, that crack propagation is discontinuous within individual crystals as well. Other evidence has been given by Low.' When discontinuous cracks within a crystal join together to make a macrocrack, the lamellae between each set of two cracks are torn somewhere, forming small cliffs. These cliffs appear as lines when the cleavage surface is observed microscopically.4,5 The lines have been called vein, tree, and riverlike markings by various authors, and they have sometimes been mistaken for fissures. The descriptive term cleavage steps is used in this paper. Cleavage steps vary in height over a wide range of values, from molecular dimensionsG to lor. and larger. Kies, Sullivan, and Irwin,2 as well as George,' have shown that the gross cleavage step patterns for plastics, polycrystalline metals, and for mono-crystals are sometimes similar. Thus, they depend mostly on the mechanical variables that prevail during cleavage and are relatively insensitive to the structure of the material. For example, parabolic markings2,7,8 sometimes result when cracks open up ahead of, and not coplanar with, the main crack front. If the advance crack has the same velocity as the main crack, their intersection line is a parabola, otherwise it is a hyperbola or an ellipse. The patterns are strongly affected by differences in crack velocities. This results in chevron patterns which point to the place of origin of the main crack. It is the purpose of this paper to demonstrate the existence of a mechanism of cleavage step formation which is a continuous rather than a discontinuous process. Also, certain characteristic step patterns are described, and the strong effect of temperature is shown. The specimens were zinc monocrystals (grown from 99.999+ pct pure metal). These were cleaved at room temperature and at — 196°C. Results and Discussion Cleavage step patterns are highly variable from point to point on a given specimen, as well as from one specimen to another. Although the patterns shown in the photographs are typical, they have been selected for graphic illustration. Figs. la and lb compare undeformed crystals that were cleaved at —196 °C and room temperature, respectively. Cleavage at room temperature (Fig. lb) resulted in a higher density of high steps (dark black lines) and enhanced the visibility of the fine background markings. Deformation by simple slip caused no marked change in the step patterns until the glide strain reached about 1.0. But, as Fig. lc shows, the density of high cleavage steps was greatly increased by large glide strains. Corrugations lying perpendicular to the slip direction may also be seen in Fig. lc. These are caused by deformation bands. The cleavage resistance of the crystal of Fig. lc was very high compared to undeformed crystals (estimated by the force on a needle required for cleavage). Striking and varied cleavage step patterns were observed on bent crystals. Two characteristic patterns that were observed on crystals bent at 25°C, and cleaved by reverse bending at —196°C, are shown in Figs. 2a and 2b. The first, Fig. 2a, consists of V-shaped lines similar to the parabolas of other materials2,7 Fig. 2b shows a pattern that is the equivalent of Fig. la, consisting of faint background lines with a few higher step markings. Cleavage of bent crystals at room temperature resulted in Figs. 2c and 2d. Now, the cleavage step lines show a strong tendency to follow one of two perpendicular paths. In Fig. 2c (bent once), many of the cleavage step components that lie parallel to the bend axis are assembled into irregular lines. In Fig. 2d (bent twice), the cleavage steps again tend to consist of two perpendicular components, but neither of the components is assembled into lines. Also, the step density is higher.

Jan 1, 1956

By J. E. Dinger, Ross Gunn

Faraday's Law of magnetic induction states that the e.m.f. acting around a closed circuit is equal to the time rate of change of flux through that circuit. If the closed circuit is a conducting medium, there will flow an electric current which is propor¬tional to the conductivity of the material and the time rate of change of the flux. Electrical currents so induced in a con¬ducting material are often referred to as eddy currents. Eddy currents are thus induced into a conducting material by (1) a time rate of change of the magnetic field through the material, by (2) a relative motion of the conducting material and a magnetic field, or by (3) a combination of (1) and (2). Because the magnitude of the induced eddy currents is dependent upon the resistance of the equivalent conducting path, these currents offer a method of detecting electrical discontinuities in a

Jan 1, 1945