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By E. H. T. Whitten

Fundamental principles of trend surface analysis are briefly reviewed. Recent analyses of several granite masses illustrate the method of estimating the quantitative regional composition and also variation trends. Mineralogi-cal, bulk chemical, and other quantitative variates can be employed. Such results should improve gravimetric surveys (etc.) relying on correction terms based upon estimated rock composition. For the first time realistic estimates of the mean composition of rock bodies can be made with the aid of trend components. Deviation maps hold promise for delimitation of disseminated mineralized areas. Deviations comprise residual "anomalies" after removal of trend components. In petrogenetic work such deviations have been shown to reflect local influences (e.g., contamination of magma by assimilation of xenoliths or country rocks of the envelope). Similarly, mineralization should be reflected as deviations standing out from background trends. Actual examples are given. Present results largely involved projection of data onto a horizontal plane, but if sufficient data are available use of three spatial coordinates increases accuracy for prediction in "unexposed" areas. Regression analysis shows that statistical correlations between variates for regionally distributed specimens are often strong (particularly with percentage data). Hence, in preliminary surveys more easily determined variates may sometimes be employed to gain first estimates of the distribution of components more economically significant. The sampling plan is of paramount importance. Unless a suitable sampling plan is devised and adhered to rigorously during collection of the samples, all subsequent analysis is liable to strong bias and to yield spurious estimates of the truth. For a wide variety of purposes it is becoming necessary to assess the quantitative composition and variability of rock masses and mineralized zones of various types. In petrology and petrography this is something of a break with tradition, because virtually all descriptions heretofore have been qualitative. Although vast amounts of qualitative data have been compiled, little is known about the quantitative behavior of rock components. However, if variability of rocks could be understood and expressed with sufficient accuracy, there would be considerable advantage to both economic and petrogenetic problems. For example, if, on the basis of a limited series of observations, the three-dimensional geometry of a disseminated orebody (or ore-bearing formation) could be predicted accurately, it would be possible to extrapolate with confidence the structure into unexposed areas. The following example based upon the geometry of an igneous cone sheet illustrates the point. The significant rock-unit gives outcrops at a number of points on the exposed surface ABCD (Fig. 1A). Study of n exposures may enable a geologist to predict that the rock-unit is circular in form and thus indicate where the unit can be expected in unexposed terrain. Such observations are made at sites with u, v coordinates, but, if subsurface information is available at sites with uvw coordinates, it will eventually become possible to predict accurately the three-dimensional form of the rock mass. Geologic rock masses or mineral deposits are not generally as regular and symmetrical in geometric form as the body illustrated in Fig. 1A. However, even where the broad limits of a major rock mass are known, a more acute problem arises in attempting to obtain detailed quantitative estimates of its internal variability; it is difficult to predict the variability of a mass from a limited number of observa-

Jan 1, 1961

By Taylor Lyman, E. P. Klier

The structures formed when austenite is quenched to subcritical temperatures and allowed to transform isothermally have been the subject of intensive study since the work of Davcnport and Bain.' Isothermal transformation diagrams summarizing the results of many of these studies have become widely familiar to metallurgists. Of particular interest to metallographers are the dark-etchingl acicular products of transformation formed by isothermal reaction below the temperature of maximum velocity of the austenite to pearlite reaction. These products, the bainite structures, can he formed in a wide variety of steels. However, the constitution of bainite is not well understood and divergent views have been expressed as to its mode of formation. In this investigation a combination of dilatometric, microscopic and X-ray methods has been brought to bear upon the problem in the hope of some elucidation of the bainite reaction as it occurs in hypo-eutectoid steels. Mechanism OF Bainite Formation Davenport and Bainl considered the mechanism of bainite formation to consist of two steps—an allotropic transformation followed by precipitation of carbide. The separation in time of the two processes was considered to be very slight in the upper temperature range and very marked at temperatures just above the martensite range. This concept has been restated by Vilella, Guellich and Bain2 in the form of a definition of the acicular mode of transformation as: The successive, abrupt formation of flat plates of supersaturated ferrite along certain crystallographic planes of the austenite grains; this supersaturated ferrite begins at once to reject carbide palticles, (not lamellae), at a rate depending upon temperature In effect, this is the acicular mode of transformation, even though the temperature be such as to limit the actual life of the quasi-martensite to millionths of a second. The investigation of isothermal decomposition of austenite in certain alloy steels (notably those containing chromium or molybdenum) has revealed that there may be a range of temperatures between the pearlite and bainite reactions in which the austenite decomposes at a relatively low rate.3-6 Further, it is characteristic that in the second region of fast reaction the decomposition of the austenite is incomplete by one reaction but goes to completion by a second reaction. These observations led Wever7 to a description of the bainite reaction as follows: I. The reaction takes place by initial precipi. tation of a martensitic intermediate structure. 2. In the upper temperature range this structure readily decomposes into ferrite and cementite. In the lower range carbon separates in an unknown form. 3. In the upper temperature range the precipitated carbide nucleates the precipitation

Jan 1, 1944

By E. P. Klier, Taylor Lyman

The structures formed when austenite is quenched to subcritical temperatures and allowed to transform isothermally have been the subject of intensive study since the work of Davcnport and Bain.' Isothermal transformation diagrams summarizing the results of many of these studies have become widely familiar to metallurgists. Of particular interest to metallographers are the dark-etchingl acicular products of transformation formed by isothermal reaction below the temperature of maximum velocity of the austenite to pearlite reaction. These products, the bainite structures, can he formed in a wide variety of steels. However, the constitution of bainite is not well understood and divergent views have been expressed as to its mode of formation. In this investigation a combination of dilatometric, microscopic and X-ray methods has been brought to bear upon the problem in the hope of some elucidation of the bainite reaction as it occurs in hypo-eutectoid steels. Mechanism OF Bainite Formation Davenport and Bainl considered the mechanism of bainite formation to consist of two steps—an allotropic transformation followed by precipitation of carbide. The separation in time of the two processes was considered to be very slight in the upper temperature range and very marked at temperatures just above the martensite range. This concept has been restated by Vilella, Guellich and Bain2 in the form of a definition of the acicular mode of transformation as: The successive, abrupt formation of flat plates of supersaturated ferrite along certain crystallographic planes of the austenite grains; this supersaturated ferrite begins at once to reject carbide palticles, (not lamellae), at a rate depending upon temperature In effect, this is the acicular mode of transformation, even though the temperature be such as to limit the actual life of the quasi-martensite to millionths of a second. The investigation of isothermal decomposition of austenite in certain alloy steels (notably those containing chromium or molybdenum) has revealed that there may be a range of temperatures between the pearlite and bainite reactions in which the austenite decomposes at a relatively low rate.3-6 Further, it is characteristic that in the second region of fast reaction the decomposition of the austenite is incomplete by one reaction but goes to completion by a second reaction. These observations led Wever7 to a description of the bainite reaction as follows: I. The reaction takes place by initial precipi. tation of a martensitic intermediate structure. 2. In the upper temperature range this structure readily decomposes into ferrite and cementite. In the lower range carbon separates in an unknown form. 3. In the upper temperature range the precipitated carbide nucleates the precipitation

Jan 1, 1944

By John Fritz

TROUGH it is not a condition of the Award, the fact is that the John Fritz Medal never has been given to an engineer who had not already received one or more similar awards. This "medal for medalists," on the evening of April 20, was presented to Daniel C. Jackling at a special dinner held at the Union League Club in New York. The citation read "For notable industrial achievement in initiating mass production of copper from low-grade ores through the application of engineering principles." The present award recognizes the same accomplishment-the launching and guiding to the port of marvelous success of the Utah Copper Co., first of the so-called "Porphyries"-as did the award of the William Lawrence Saunders Gold Medal by the A.I.M.E. in 1930, and before that the Award of the Gold Medal of the Mining and Metallurgical Society of America in 1926. Following the custom a biography of the Medalist had been published in a small pamphlet as a supplement to the John Fritz Medal Book. T. A. Rickard was the au¬thor of the sketch of Mr. Jackling, an innovation being the placing of a copy of the booklet at the place of each of the diners. The committee in charge of the dinner consisted of two past-presidents: R. E. Tally, of the A.I.M.E., who was chairman; Bancroft Gherardi, of the A.I.E.E.; and Thaddeus Merriman, director of the A. S. C. E., the John Fritz Medal being a joint award of the four societies. Frederick M. Becket, President of the A.I.M.E., as chairman for the occasion, briefly stated the purpose of the dinner. He stressed his satisfaction that the award was symbolic of the cooperative professional activities of the four great national organizations of engineers. He introduced Francis Lee Stuart, past-president of the A.S.C.E. and now chairman of the John Fritz Medal Board of Award. Mr. Stuart outlined the history and purpose of the Medal established in 1902 in memory of John Fritz, of Bethlehem, Pa., one of the great pioneers of America's iron and steel industry, metallurgist, and president of the A.I.M.E. in 1894. Mr. Stuart called the roll of former John Fritz Medalists, three of whom, Ralph Modjeski, J. Waldo Smith, and Ambrose Swasey, were present to do honor to Mr. Jackling. He then introduced George Otis Smith, whose privilege it was to present the Medalist for 1933. Dr. Smith was the senior of the four A.I.M.E. representatives on the Board that last year selected Mr. Jackling for the honor. His speech follows in full.

Jan 1, 1933

By Paul M. Tyler

ROUGHLY one-half the value of mineral products at mines or quarries must be spent for wages. In view of the steady increase in hourly wages that continued for several decades prior to the onslaught of the recent depression, it is perhaps surprising to discover that labor's share of the gross proceeds of the mining and quarrying industries of the United States declined to 46.8 per cent in 1929, compared with 52.2 per cent in 1919 and 53.2 per cent in 1909. The actual percentages vary in different branches of the industry and in different localities but the downward trend is unmistakable. For the period 1909 to 1919 it was quite marked in every industry and from 1919 to 1929 it was apparent in all but six: namely, gold and silver lode mining, placer gold mining, crude gypsum production, marble quarrying, asbestos production, and fluorspar Tninino mining

Jan 1, 1933

By Arthur T. Word

STANDING room only seemed to be the order at the annual session and luncheon of the Eastern magnetite committee. Gatehouse check at the former indicated at least 80, with 33 attending the luncheon - all the crowded facilities could handle. Chairman Crockett opened the meeting by calling upon Meredith E. Johnson, who presented his illustrated paper on "Prospecting for Iron Ore in New Jersey in 1943." This "wartime" brief was discussed by Lucien Eaton, P. W. Henry, and Chairman Crockett. H. E. Hawkes, Jr., of the U. S. Geological Survey, then presented his unscheduled paper on the "Magnetite Deposits of the Jersey Highlands." Discussion was by A. W. Pinger and Chairman Crockett. Fred E. Stiefel then described shaft sinking at the Fisher Hill mine of the Republic Steel Corp., giving a detailed description of how modern

Jan 1, 1944

R. Schuhmann, Jr. (Purdue University)— Fulton and Chipman's results on rate of silica reduction from slags are analogous in many was to the results of Parlee, Seagle, and Schuhmann10 on rate of alumina reduction from alumina crucibles. Both investigations have given comparably low rates of reduction and slow approaches to equilibrium. Accordingly, we may hypothesize that the rate-determining step is the same in both kinds of experiments; that is, oxygen diffusion across the stagnant boundary layer on the liquid-metal side of the interface between the liquid metal and the oxide phase (slag or solid oxide). I suggest that silica reduction involves the following consecutive steps: I) At the slag-metal interface: SiO2(slag) Si+ 20 II) Transport of oxygen from slag-metal to gas-metal interface: a) diffusion across liquid-metal boundary layer at slag-metal interface. b) convection within the body of liquid metal. c) diffusion across boundary layer at metal-gas interface. 111) At the metal-gas interface: C +O- CO (gas) Iv) At the graphite-metal interface: C (graphite) -C At steelmaking temperatures it is reasonable to assume that equilibrium is attained in all three chemical reactions (I, 111, and IV) right at the respective interfaces. Convection within the stirred liquid metal (step IIb) is also rapid. Transport of Si and C should be orders of magnitude easier than transport of 0, because of the relatively high concentrations of Si and C. Accordingly, we might expect the overall reaction rate to be determined by boundary-layer diffusion of oxygen, either IIa or IIc. Fulton and Chipman's demonstration that bubbling CO through the system had no major effect on reaction rate indicates that IIc is not the slowest step. Therefore, it becomes logical to estimate the maximum rate for step IIa and to compare this theoretical estimate with Fulton and Chipman's experimental data. If oxygen diffusion across the liquid metal boundary layer at the slag metal interface (step IIa) is rate-determining, In this equation, dn sio, /dt is the rate of silica reduction in moles per sec,A is the area of slag-metal interface in sq cm, Do is the diffusivity of oxygen in sq cm per sec, 6, is the boundary layer thickness in cm, c,* is the oxygen concentration right at the slag-metal interface in moles per cubic cm, and co is the oxygen concentration in the body of the liquid metal, also in moles per cubic cm. Equilibrium data" on the silicon deoxidation reaction in liquid iron and steel at 1600°C indicate that the oxygen contents of the liquid metal in Fulton and Chipman's experiments at 1600°C probably fell in the range of 0.5 x10-3 x10-3wt pct. That is, the maximum conceivable value of co*-co for the system under consideration was on the order of 10"5 mole oxygen per cubic cm. On the basis of previously published data,1O,11 it is estimated that Do/0 will fall somewhere in the range from 10-3 to 10-1 cm per sec. The surface area A in Fulton and Chipman's experiments was approximately 20 sq cm, and the weight of metal involved was about 500 grams. Combination of all these figures with the above rate equation leads to an estimate that the rate of silica reduction should fall within the range from 0.002 to 0.2 wt pct Si per hr. This estimate is consistent with the experimental data. For example, Fulton and Chipman's Fig. 2 shows a change of about 0.3 pct Si in 10 hr, corresponding to an average rate of 0.03 pct per hr. According to the proposed hypothesis, increasing the temperature will increase the reaction rate ill two ways: 1) by increasing oxygen diffusivity and 2) by increasing the oxygen concentration (oxygen solubility) in the liquid metal. The combination of these two effects accounts for the high value of the observed activation energy. Summarizing, I propose that the rate of silica reduction, like that of the carbon-oxygen reaction, is diffusion controlled and that low oxygen concentration in the liquid metal is the major factor accounting for the very low observed rates of silica reduction. John Chipman (author's reply)—The authors thank Professor Schuhmann for his interesting contribution. His proposed explanation may well prove to be the correct one. There is clearly a need for much further experimental work on this problem, and further research is in progress.

Jan 1, 1961

By B. B. Rath, Hsun Hu

In wedge-shaped bicrystals of zone-refined aluminum it is observed that (111) pure tilt boundaries migrate under the driving force of their own inter-facial free energy. The boundary velocity is a power function of the driving force. The driving force exponent decreases with decreasing angle of misorien-tation. For example, at 64O°C, the exponent decreased from 4.0 for a 40 deg to 3.2 for a 16 deg tilt boundary. An evaluation of the driving force acting on the boundaries during their motion indicates that for low driv-forces, up to about 2 x l03 ergs per cu cm, the velocity is relatively independent of misorientation, whereas at higher driving forces a 40 deg tilt boundary exhibits the highest velocity. The measured activation energy for boundary migration approaches that for bulk self-diffusion at low driving forces, decreasing from 33 to 27 kcal per mole as the driving force is increased from 1 x l0 to 5 x l03 ergs per cu cm. These results are compared with current theories of grain-boundary migration. In previous experimental studies of grain boundary migration the driving force has been limited to a difference in stored energy across the boundary. This stored energy has been introduced into the crystal either by prior deformation1-3 or by grown-in lineage structure. A part of the energy stored in the deformed crystal is released by recovery either prior to or concurrently with grain boundary migration, thus introducing an uncertainty as to the magnitude of the driving force responsible for grain boundary migration. The grown-in lineage structure, though thermally stable during annealing, neither provides conditions under which different levels of energy may be stored in the imperfect crystal nor provides a control of orientation difference across the migrating boundary of a growing grain. Furthermore, because of variation in the lineage structure, it is difficult to determine accurately the energy stored in the imperfect crystal. Several investigations of grain boundary migration during normal grain growth have also suffered from difficulties in estimating the driving force because of uncertainties in the principal radii of curvature.~ In the present investigation the velocity of pure tilt boundaries in zone-refined aluminum bicrystals of selected orientation (40, 30, and 16 deg around the [Ill] tilt axis) has been measured in the absence of a dislocation density difference across the moving boundary, thus eliminating the previous experimental difficulties. The driving force for boundary migration is derived from a gradient of the total interfacial free energy of the migrating boundary in wedge-shaped bicrystals. A similar method was attempted by Bron and Machlin in a study of grain boundary migration in silver. However, they found that one of the crystals was deformed and consequently the motion of the boundary was partly due to a difference of stored energy across the boundary. The observed behavior of boundary velocities as affected by the driving force is examined in the light of the predictions of the current theories of grain boundary migration.7"10 The effect of boundary misorientation on velocity is compared with the theory of " which is based on a dislocation core model for high-angle boundaries. EXPERIMENTAL METHOD Seed-oriented bicrystals of zone-refined aluminum, 2.5 cm wide, 0.5 cm thick, and 12 cm long, containing tilt boundaries with a common (111) axis, were grown from the melt in the direction of this axis. Spectro-graphic analysis, reported earlier,'' indicated the purity of the crystals to be 99.999+pct. Three such bicrystals containing 16, 30, and 40 deg tilt boundaries were used. Wedge-shaped specimens were prepared from these bicrystals by spark cutting followed by electrolytic polishing. The angle of the wedge was usually 40 deg and the specimens were usually 0.25 cm thick. The intercrystalline boundary was located within 0.2 to 0.5 cm from the tip of the wedge. Fig. 1 shows a section of an oriented bicrystal containing an outline of a wedge-shaped specimen. The crystallographic directions shown in Fig. 1 represent the orientation of one of the crystals (the larger section of the bicrys-tal); the orientation of the other crystal differs only by rotation around the common [lil] axis. The parallel faces of the wedge always corresponded to the common (171) planes in both crystals, whereas the orientation of the side faces varied, depending on the misorientation angle. The bicrystal orientations were determined

Jan 1, 1970

Jan 1, 1967

By A. B. Cox, L. W. Wark

An attempt has been made to compare the influences of the two most widely used depressants—alkalis and sodium cyanide—and the most widely used activator—copper sulfate—on the air-mineral contact induced by five sulfur-bearing compounds: (1) sodium di-ethyl dithio-phosphate (sodium Aerofloat); (2) potassium ethyl xanthate; (3) sodium di-ethyl dithiocarbamate; (4) potassium iso-amyl xanthate; (5) potassium di-n-amyl dithiocarbamate. Three different organic types are included in lhis group and for two of these types a higher and a lower homologue have been tested. The study of potassium ethyl xanthate, the preliminary results of which have been described,' was continued until there had been obtained a comprehensive account of the influence of variations in pH value and in the concentrations of xanthate, sodium cyanide and copper sulfate on the adsorption of this xanthate by galena, sphalerite, pyrite and chalcopyrite. With concentrations of copper sulfate and collector that the work with ethyl xanthate indicated would give the most illuminating. results, the other four collectors were tested, in a less exhaustive way. The same general principles determine the influence of alkalis, cyanide and copper sulfate, no matter to which type the collector belongs, but there is a gradation in the quantitative measure of such influence. In the list above, the five collectors are cited in the order of their capacity to withstand the depressants, sodium Aerofloat being the least resistant, potassium di-n-amyl dithiocarbamate the most resistant. This order coincides substantially with that of the solubilities of the heavy metal salts formed by double decomposition with the collectors, those formed from sodium Aerofloat being most soluble. There is little difference between the third and fourth members of the series, and under certain conditions their positions are reversed. In general, then, of the three types of collectors investigated, the dithiophosphate type is most easily influenced by depressants, and the

Jan 1, 1935

By E. P. Klier, Taylor Lyman

THE structures formed when austenite is quenched to subcritical temperatures and allowed to transform isothermally have been the subject of intensive study since the work of Davenport and Bain.1 Isothermal transformation diagrams summarizing the results of many of these studies have become widely familiar to metallurgists. Of particular interest to metallographers are the dark-etching, acicular products of transformation formed by isothermal reaction below the temperature of maximum velocity of the austenite to pearlite reaction. These products, the bainite structures, can be formed in a wide variety of steels. However, the constitution of bainite is not well understood and divergent views have been expressed as to its mode of formation. In this investigation a combination of dilatometric, microscopic and X-ray methods has been brought to bear upon the problem in the hope of some elucidation of the bainite reaction as it occurs in hypoeutectoid steels. MECHANISM OF BAINITE FORMATION Davenport and Bain1 considered the mechanism of bainite formation to consist of two steps-an allotropic transformation followed by precipitation of carbide. The separation in time of the two processes was considered to be very slight in the upper temperature range and very marked at temperatures just above the martensite range. This concept has been restated by Vilella, Guellich and Bain2 in the form of a definition of the acicular mode of transformation as: The successive, abrupt formation of flat plates of supersaturated ferrite along certain crystallographic planes of the austenite grains; this supersaturated ferrite begins at once to reject carbide particles, (not lamellae), at a rate depending upon temperature. In effect, this is the acicular mode of transformation, even though the temperature be such as to limit the actual life of the quasi-martensite to millionths of a second. The investigation of isothermal decomposition of austenite in certain alloy steels (notably those containing chromium or molybdenum) has revealed that there may be a range of temperatures between the pearlite and bainite reactions in which the austenite decomposes at a relatively low rate.3-6 Further, it is characteristic that in the second region of fast reaction the decomposition of the austenite is incomplete by one reaction but goes to completion by a second reaction. These observations led Wever7 to a description of the bainite reaction as follows: I. The reaction takes place by initial precipitation of a martensitic intermediate structure. 2. In the upper temperature range this structure readily decomposes into ferrite and cementite. In the lower range carbon separates in an unknown form. 3. In the upper temperature range the precipitated carbide nucleates the precipitation

Jan 1, 1944

By C. R. Wohrman

A MELT of pure electrolytic iron with about 0.4 per cent. sulfur and 7 per cent. manganese was prepared in connection with a study of inclusions in iron. The alloy darkened rapidly when etched with a 10 per cent. alcoholic solution of nitric acid, and microscopic examination revealed the presence of a semimartensitic, semi-Widmanstättian structure (Figs. 1 and 2) closely resembling the structures found by Benedicks in his artificially prepared "meteoric iron." 1 The structures found by Benedicks were readily explained by the presence in his alloy of the two well known iron-nickel solid solutions, taenite and kamacite, and of their eutectoid (?) aggregate, plessite. By analogy, one would infer the existence of similar phases in the iron-manganese alloy just described, such as inference being strengthened by the similarity displayed in many ways by nickel and manganese in their effects on iron. IRON-MANGANESE ALLOTS ARE REGARDED AS HOMOGENEOUS Heterogeneity of iron-manganese alloys has not been recognized heretofore, judging from the data of standard metallographic books and those of original papers. In fact, iron and manganese are quite generally regarded as completely miscible in the solid state. Dr. Rosenhain,2 for example, writes: Alloys of group (a), of which those of gold-silver, iron-manganese, and copper-nickel are examples, when allowed to crystallize sufficiently slowly to attain their condition of final equilibrium, present a microstructure exactly similar to that of a pure metal-the homogeneous character of the molten solution is in that case so completely maintained that the microscope cannot detect the presence of any second constituent.

Jan 1, 1927

By H. M. Chance

Adequate treatment of the difficulties surrounding the valuation of mineral lands requires that agreement be first reached defining value as understood for the purpose of appraisal. To define value as the price of a product is not sufficient, and does not assist us in using the factors that cause variations in values and in relative values. The real value of any product depends primarily upon its relation to the necessities, comforts and pleasures of mankind. As the necessities, comforts and pleasures of the civilized races differ from those of more primitive man, the value of products varies with the degree of civilization and the environment of the consumer. Coal has no value to the savages of warm climates, and arrow-head flint none to the residents of New York. It has long been recognized that what has been termed " intrinsic value " must be limited to materials that are essential to existence—air, water, food. But " intriusic value" cannot be measured in monetary terms. The intrinsic value of a bushel of wheat is due to the fact that it will support the life of an individual for a certain definite time, but this fact does not enable us to measure or to express that value in monetary terms. It has often been proposed to adopt as a measure of the value of any product the quantity of labor necessary to produce it, but this method is of limited application, and will not apply to what may be termed " intrinsic values." For many reasons it might be well, while assenting to the fact that any material may be intrinsically valuable, to abandon the use of the term " intrinsic value." One of these reasons is the tendency to confuse the idea of intrinsic value with a value that is conferred by economic conditions, that is purely artificial and that may be permanent or evanescent. Intrinsic value must from its nature be permanent and unchangeable. Possibly for present purposes the value of any material may be considered as having a dual origin: First, that due to economic

Jan 1, 1914

By Magnus Troilius

The heat-calculations of gas-analyses involve cumbrous multiplications, which are apt to lead into errors. The foliowing tables and formulae have been found useful as facilitating such calculations, and therefore I hope that they will be of interest to some of the members. By "heat-unit" will, in the following, be understood the amount of heat required to raise the temperature of 1 kilogram of water l° Cent. All the tables refer to cubic meters at O0 and 760 mm. pressure. The following gas is chosen as an example: C02, - 4.0 vol. per cent. co, = 20.0 " CHI, - 3.5 " H, - 7.0 " N, - 65.5 " " 100.0

Jan 1, 1884

By L. M. Higgins

Dust or fume control systems are devices for capturing contaminants at their source and preventing their discharge to atmosphere. The Primary Components Of Any Dust Control System Include: An enclosure around any potential dust source such as conveyor belt transfer, crusher, screening machine, bin loading and loadout. Ductwork including hood takeoffs (transitions) to convey the collected dust laden air away from the source of dust generation to a convenient location. A dust collector for separation of particulate matter from the air stream prior to its discharge to the atmosphere. A prime mover generally a fan, to draw air into an enclosure and to overcome resistance to flow in the ductwork, dust collector and stack.

Jan 1, 1978

By Paul M. Tyler

The term "milling" as applied to nonmetallic minerals often refers merely to pulverizing without preliminary beneficiation. As applied to dimension stone, it embraces all the gteps involved in shaping and giving the desired finish to blocks. Processes such as sawing, planing, rubbing and polishing seem far removed from milling as the term is used in ore dressing, nevertheless they involve the element of concentration, for only 25 to 50 per cent of the gross quarry output may leave the mill as finished products after imperfect stone has been culled and the rough blocks trimmed. On the other hand, numerous nonmetallic minerals have to be concentrated in much the same manner as low-grade ores. Engineers and machinery manufacturers have begun to recognize more clearly the opportunities awaiting them in the nonmetallic field and have brought with them the methods and equipment developed in metal-mining camps, occasionally with little modification. General Economic Considerations Approximately one-half of the total value of the mineral production of the United States represents mineral fuels, and the other half is about equally divided between metals and nonmetals, the nonmetals recently having become relatively more important. In terms of volume the domestic output of nonmetallic minerals other than fuels is more than 10 times the annual output of metals. Considered on the basis of industrial utility and general commercial and military significance, moreover, the flow of nonmetallic mineral products is quite as needful to our national integrity and well-being as is that of metals, fuels, or other basic materials. Despite their importance individually and as a group, the nonmetallic mineral industries differ so widely in essential characters and economic environment that producers thereof have been slow to develop a community of interest among themselves or with the metal-mining fraternity. A spirit of change is in the air, rule-of-thumb methods soon may be relegated to limbo, and new methods—especially time-tested ideas borrowed from ore-dressing practice—are being introduced. A faithful record of plant practice in certain of these fields, however, must register

Jan 1, 1935

By W. L. Doyle

SLAG weights were taken on a series of twenty-eight 6-ton bottom-pour heats. These weights varied from 573 to 1050 lb. Of these, four were chosen for study of the effect of cleaned and uncleaned foundry scrap on the variations of slag weights. Data regarding the make-up and results of the heats are given in Table I. For heat No. 3 the actual slag weight was checked, using the Mn-MnO calculation method-weight 1050 lb. [5,600 X 0.0055 = 30.80 heads and gates 6,000 X 0.004 = 27.00 plate scrap 800 X 0.0083 = 6.64 pig iron 450 X 0.0034 = 1.53 iron ore]

Jan 1, 1947

By Sam Tour

SOME years ago, the writer described heat checks or thermal cracks that occur in die-casting dies.1 The life of dies was considered in relation to the casting temperature, the material used for the die, and the heat to be absorbed by the die per unit volume of casting made. The mech-anism of the action that results in thermal failure of dies was described. In the present paper the writer proposes to describe some additional observations in regard to heat checking, make one or two suggestions as to the method or methods for further attack of the problem, and give the results obtained on some work carried out along these lines.

Jan 1, 1934

By Sam Tour

SOME years ago, the writer described heat checks or thermal. cracks that occur in die-casting dies.1 The life of dies was considered in relation to the casting temperature, the material used for the die, and the heat to be absorbed by the die per unit volume of casting made. The mech-anism of the action that results in thermal failure of dies was described. In the present paper the writer proposes to describe some additional observations in regard to heat checking, make one or two suggestions as to the method or methods for further attack of the problem, and give the results obtained on some work carried out along these lines.

Jan 1, 1934

By John M. Lovejoy

FEDERAL regulation of the petroleum resources of the nation has long been an interesting topic for discussion. A plan to accomplish Federal control has now taken definite form. At the request of the President of the United States, a bill to be known as the Petroleum Conservation Act of 1939 has been presented to Congress-H. R. 7372, offered by Representative Wm. P. Cole, Jr., and more usually known as the Cole bill. It is an act ostensibly designed to conserve our petroleum resources, through regulation of production practices. Hearings are being held currently by a subcommittee of the Interstate and Foreign Commerce Committee, in compliance with the request of the President to report the bill early in the next session of Congress.

Jan 1, 1939