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By Thomas F. Torries, George H. K. Schenck

Crushed and broken stone is used directly in construction as an aggregate and accounts for about half the value and two-fifths of the quantity of natural aggregates consumed in the United States. Sand and gravel provide most of the balance of aggregates except for some lightweight materials such as pumice and expanded shale. Conditions necessary for production of crushed stone from a deposit are : 1) Quality-should pass rigid specifications for strength and durability. 2) Cost-low average total delivered cost. Construction aggregates are hard, essentially inert materials suitable for being formed into a stable mass either (1) by the addition of cementing or binding materials that produce a concrete or (2) by compaction or by natural weight to produce a road base or foundation. Aggregates usually provide about 80 to 100% of the material volume of the construction masses in which they are used. The construction industry utilizes as aggregates about 70% of all crushed stone produced in the United States according to statistics provided by the U.S. Bureau of Mines (USBM) , [Table 1], using definitions as shown below. Nonconstruction uses of crushed stone, [Table 2], are included elsewhere in Industrial Minerals and Rocks because such uses require the special physical or chemical characteristics which are discussed in those chapters.

Jan 1, 1975

By W. A. Tiller, J. P. McHugh

HE majority of liquidus and solidus surfaces in phase diagrams have been determined by the conventional cooling- and heating-curve techniques.' These techniques have two main shortcomings: 1) the solidus may be in considerable error due to the difficulty involved in completely homogenizing the solid and 2) the determination of liquidus and solidus in more than a two-component system does not enable one to determine tie-lines connecting the specific equilibrium solid and liquid compositions. However, in a recent paper by one of the authors,' a method was suggested whereby the liquidus and solidus surfaces plus tie-lines in an n-component system may be determined. This method utilizes a controlled solidification technique and assumes that interface equilibrium exists during freezing. The present work was undertaken with a twofold purpose; first, to determine the liquidus and solidus lines in the pseudo-binary system Bi2Te3-Bi2Se3 by heating- and cooling-curve techniques and, second, to determine the partition coefficients of Te and Se in the BizTe3-,Sex system by controlled solidifica- tion techniques. The two sets of results can be compared to test the accuracy of the controlled solidification method. EXPERIMENTAL I—The starting materials for this study were 997999 pct Bi, Te, and Se, obtained from the American Smelting and Refining Co. The compounds BizTe, and Bi2Se3 were each prepared by melting together stoichiometric amounts of the elements, followed by twelve zone-refining passes. This produced homogeneous bars of the compounds for use in the phase-diagram studies. The apparatus used to obtain heating and cooling curves is illustrated schematically in Fig. 1. The alloy samples were located in a graphite crucible placed in a stainless steel canister. The canister was supported in a heavily lagged pit furnace by a device which oscillated the canister about its vertical axis at a frequency of about 3 cycles per sec during heating and cooling-curve runs. The graphite crucible was designed to minimize the thermal coupling of the sample to the furnace. A thin graphite sleeve separated the alloy sample from the stainless steel tube that housed the thermo-

Jan 1, 1960

By C. H. Li, R. J. Stokes, T. L. Johnston

A portion of the Ni3Cr-Ni3Al phase dzagram has been investigated, including the precipitation of 1 (Ni3Al) as well as the existence of ordered Y (Ni matrix), Extensive metallographic studies by electron microscopy have been carried out and X-ray diffraction diagrams have been taken at both elevated and ambient temperatures, No long-range ordering of the phase was found above 893°C (1639°F) in the compositional range investigated. The high rate of formation of the ordered ?1 phase upon quenching has been confirmed, a phenomenon which up to the present Lime has retarded the understanding of this phase diagram, Specimens with controlled amounts of ?1 exhibited up to a six-fold improvement in yield and creep strength compared with single-phase Ni-Cv-A1 alloys. MOST of the important high nickel heat-resistant alloys are related to the nickel-chromium-aluminum system. One of the important functions of the aluminum, often accompanied by titanium, is to produce a precipitate of the very fine ?1 phase (Ni3A1, X) where X may be Ti, Cr, or other elements. A number of investigators1-" have demonstrate the presence of y' in these alloys but most of their materials contained large amounts of other elements resulting in appreciable amounts of con- fusing phases such as carbides. Further clouding of the precise role of y' has been the suspected existence of an ordering reaction in the y matrix itself, ro-3,12-17 It appeared from these investigations that aluminum in Ni-Cr alloys would raise the ordering temperature of the matrix from 540°C at NisCr to 1300°C at Ni,Al. In support of this possibility, the matrix phase in the parallel Ni-Fe-A1 system is ordered to very high temperatures.1 OBJECTIVES OF THIS RESEARCH From this survey of the literature it appeared desirable to conduct an investigation of the simple Ni-Cr-A1 system using the alloys of the highest available purity to avoid the complication of foreign phases and thereby isolate the structures in the Ni-Cr-A1 system. Procedures were developed to study ? - ?o and ? - ?1 equilibria. Preliminary mechanical tests at elevated temperatures were also conducted.

Jan 1, 1962

By R. W. Raymond

ChaRles William HenRy Kirchhoff was born March 28, 1853, at San Francisco, Cal., where his father, Charles Kirchhoff, was at that time consul for his native country, Germany. A few years later, the family moved' to Hoboken, K. J., in which city the son received his preliminary education at the Hoboken Academy, proceeding later to Germany, where he was graduated in 1874 as mining engineer and metallurgist at the Prussian Royal Mining Academy of Clausthal, in the Harz. Upon his return to the United States, he became chemist of the Delaware Lead Refinery at Philadelphia, and retained that position for three years. But in 1877 he began what was to be an almost uninterrupted life-long association with David Williams, the publisher of The Iron Age, of New York, who established in that year, and continued for a brief period, a journal entitled the Metallurgical Review, on the editorial staff of which Mr. Kirchhoff received a place. The enterprise was doubtless an attempt to cover a wide metallurgical field outside of that which properly belonged to The Iron Age. But it was soon abandoned, and Mr. Williams wisely concentrated his energies upon the older journal, which, under his vigorous and skillful management, and the labors of the able editors and correspondents whom he selected, became one of the greatest institutions of its class in the world. From 1878 to 1881, Mr. Kirchhoff was assistant editor of The Iron Age. From 1881 to 1884, he was managing editor of the Engineering and Mining Journal; in 1884 he returned to The Iron Age, to become for five years its associate editor, and in 1889, on the retirement of James C. Bayles, editor-in-chief. This list of dates and employments, without further comment, sufficiently indicates, at least to the eye of an expert, that Mr. Kirchhoff had found his congenial career in trade journalism. His qualifications for this profession were somewhat exceptional. He possessed the scientific training, the knowledge of foreign languages and literatures, and the power of making and keeping friends, which enabled him to get early notice of technical novelties; he had the taste for statistics which made him both industrious and intelligent in their collection and use; and to these traits he added a mastery of the meaning of such accumulated data, and a sane, critical judgment of the situations which they represented, as well as of the sources and the figures themselves, which made his opinion weighty

Jan 1, 1917

By Walter Kauenhowen

GeRmany's crude-oil production during 1936 totaled 3,112,494 bbl., an increase of 5.2 per cent over the 3,007,711 bbl. produced in 1935. The official monthly production figures published in 1936 report only the individual production figures of the three old established fields, whereas since 1936 official reports combine the production of all other fields into one figure. According to these published data, and using a conversion factor of 1 metric ton equaling 7 bbl., the oil production of Germany in 1936 was as follows:

Jan 1, 1937

Engineering Experiment Station, University of Arkansas, Fayetteville, Ark. W N Gladson, Dean and Director The Engineering Experiment Station has published a number of bulletins, only a few of which are of particular interest in this directory: Bulletin 3, Arkansas coal or oil for domestic heating; 4, Road materials of Arkansas, 5, A study of Arkansas coals, 6, Portland cement materials in Arkansas; 11, Natural gas versus Arkansas coal for house heating. Circular 3, Short cuts to combustion efficiency with natural gas Address the Engineering Experiment Station for any of these publications.

Jan 1, 1933

By D. H. Wertz, R. R. Furlong

A. E. LEE*—I would like to ask Mr. Neale if he has determined the moisture content of his dried retort. Also, has he ever experienced difficulty with bending in the dry room where the green wel retorts contain 17 pet moisture and are placed 3 in. apart? M. M. NEALE (replying for authors)— I cannot answer your first question as we have had no experience with that. Setting the retorts 3 in. apart, we had no trouble with bending. We thought we would, anticipated we would, but did not. L. P. DVVIDSON*—You mention,

Jan 1, 1950

By L. W. Kempf, K. R. Van Horn

DURING the recent development of aluminum alloys for free-cutting screw-machine rod, it became desirable to know something of the solubility of lead and bismuth in liquid aluminum and in some aluminum alloys. The literature is not particularly helpful in supplying this information. These portions, therefore, of the constitutional relationships of aluminum-bismuth and aluminum-lead alloys were investigated by thermal analysis and by chemical analysis of samples taken from aluminum-rich melts in equilibrium with precipitated lead or bismuth. The solubility of lead and bismuth in some liquid aluminum-copper alloys was also investigated. Some consideration was also given to the solubility of these elements in solid aluminum. Among the earliest investigators of the aluminum-lead and aluminum-bismuth systems was Wright,1 who reported that melts of aluminum and lead formed two layers indicating limited liquid solubility. Under his conditions, the aluminum-rich layer was reported to contain 1.91 per cent Pb and the lead-rich layer, 0.07 per. cent Al. Subsequently, Pecheau2 found that in aluminum-rich alloy melts with more than 10 per cent Pb three layers were distinguishable. He reported that the middle layer contained from 3 to 10 per cent Pb. He also found that the melting point of aluminum appeared to be lowered slightly by the addition of lead. Gwyer3 investigated these alloys and found evidence of a slight lowering of the freezing point of aluminum by the addition of either lead or bismuth. He found no evidence of solid solubility in either case and made no attempt to determine the liquidus curves. Hansen and Blumenthal4 reported that the addition of lead distinctly lowered the solidification point of aluminum. They also found that bismuth lowered the melting point of aluminum. Guillet5 reported almost complete mutual immiscibility for the aluminum-bismuth alloys in the liquid state. Bohner6 examined the effect of various concentrations of lead and bismuth on the electrical conductivity of aluminum. He found decreases in conductivity on annealing at 500° C. as compared with the conductivity of the same alloys on annealing at 300° C.

Jan 1, 1938

By J. J. Foster

MOST of us will, I think, agree that never before in the history of the coal industry has the human side of our business been so important as today. Since, even in wholly mechanized mining, labor cost is such a large percentage of out total cost we are all deeply concerned not only about the present attitude of our employees but particularly about the future, when the industry returns to a "survival of the fittest" basis. Many things could and should be done about our employee relations in the coal business. Failure to recognize these obligations and do something about them may lead to serious consequences, the least serious of which will be the loss not only of many of our better employees but a large portion of our potential employees, as they graduate from our schools to other in¬dustries. Some of these things should be handled by the industry as a whole whereas others should be done by individual companies. Due to varying conditions and size of organizations it would, at best, be necessary to vary a program to meet the individual needs of each operator.

Jan 1, 1945

By Eric Sinkinson

MANY of the magnesite ores of the western part of the United States contain such large amounts of silica and hydrous silicate minerals that the value of the ores is either low or nominal. Expensive and carefully controlled mining methods are necessary to prevent excessive dilution of the higher grade ores by introduction in mining' of small pieces of the hanging walls or footwalls of the deposit. This difficulty is further complicated by the various states of decomposition of the country rock of the deposits in which many of the ores occur. The problem the authors attempted to solve arose from a request to float an impure magnesite containing varying proportions of siliceous gangue with calcium carbonate. The ore is normally. enclosed in serpen-tine masses, somewhat decomposed, and in mining it wall rock is inci-dentally added, so that variable amounts of siliceous material occur in the samples. The silica, alumina, and iron oxide are so closely associated with the magnesium carbonate in the magnesite that ordinary mechanical separation at coarse mesh sizes is of no avail. It is well known that calcium carbonate can be floated by suitable reagents, therefore it seemed reasonable to suppose that magnesium carbonate minerals would behave in a similar manner, but experimental trial proved that this supposition was unfounded. Therefore the first step in the problem was to find out what differences of behavior there were between magnesium and calcium carbonates under flotation conditions, or when suspended in water. In water at 18° C. magnesium carbonate is slightly more soluble than calcium carbonate; in fact, MgCO3 is soluble to the extent of 0.0106 grams in 100 c.c. of water at 18° C. and CaCO3 to the extent of 0.0013 grams. However, magnesium carbonate in water gradually changes to the basic carbonates of a composition (3MgCO3.Mg(OH)23H20) or (4MgCO3.Mg(OH)25H20), depending upon conditions, and calcium carbonate to calcium hydroxide, Ca(OH)2, The relative solubilities of these hydroxides in water are the reverse of the solubilities of magnesium and calcium carbonates.. The range in published figures for solubility

Jan 1, 1936

E P MATHEWSON, Disttrict 0 NEW YORK, N Y PAST PRESIDENTS EDWIN LUDLOW, District 0 NEW YORK, N Y ARTHUR S DWIGHT, District 0 NEW YORK, N Y FIRST VICE-PRESIDENT J V, W REYNDERS, NEW YORK, N Y TREASURER CHARLES F RAND, NEW YORK, N Y

Jan 1, 1923

By Harold B. Fell

MANY oil producers are in disagreement with the idea held by some that an increase in the price of crude oil would be unlikely to stimulate much production and that we will be obliged to draw upon foreign sources of petroleum to supplement our domestic production as the years go by. Supporting our con trary opinion are numerous facts and figures. The most recent official estimate of the maximum efficient rate of production from the oil wells of the United States is 5,271,000 bbl per day. The Economics Advisory Committee of the Interstate Oil Compact Commission estimates, assuming certain supplies from imports and from natural gasoline and benzol, that crude oil require-

Jan 1, 1947

By C. S. Roberts

Microstructural studies of a Mg-10.3 pct Al alloy showed that discontinuous precipitation during aging multiplies the grain boundary area available for easy deformation in elevated temperature creep. An increase of strain rate for a 6.2 pct Al alloy at 400°F, where precipitation and creep are concurrent, caused an increase in the volume percentage discontinuously precipitated at the completion of the process. The relatively poor elevated temperature creep resistance of heat treated alloys of the Mg-AI-Zn type was explained in these structural terms. C resistance of the heat treatable Mg-A1 based alloys is poor compared to that of Mg-Ce based alloys. While the latter show a continuous precipitate, Mg-A1 alloys prefer a discontinuous precipitate at grain boundaries. '.:' It has been concluded that the excellent creep resistance of Mg-Ce alloys was primarily due to the continuous precipitation which especially localized at the grain boundaries.' The purpose of the present investigation was to obtain a parallel correlation, if such exists, between the poor creep resistance and the state of precipitation in Mg-A1 alloys. Discontinuous precipitation produces about three times as many true grain boundaries as originally existed. This microstructure would be expected to have a marked influence in creep, where quantity of grain boundary area is important. Experimental Procedure The two experimental alloys contained 6.2 and 10.3 pct Al. They were made from electrolytic magnesium by alloying under flux and casting in 3 in. diam permanent molds. The ingots were extruded into 1 1/4 x 1/8 in. flat stock under the following conditions: billet preheat 700°F (2 hr), container and die temperature 700°F, speed 3 fpm, and area reduction ratio 45:1. The creep specimens were machined from blanks which had been solution heat treated 24 hr at 770°F and aged 16 hr at 400°F. Attempts were made to control the grain size as closely as possible for extruded stock. The grain size after solution heat treatment was about two thousandths of an inch for the 6.2 and five thousandths for the 10.3 pct Al alloy.

Jan 1, 1957

By S. D. Michaelson, Eric Sinkinson

Many of the magnesite ores of the western part of the United States contain such large amounts of silica and hydrous silicate minerals that the value of the ores is either low or nominal. Expensive and carefully controlled mining methods are necessary to prevent excessive dilution of the higher grade ores by introduction in mining of small pieces of the hanging walls or footwalls of the deposit. This difficulty is further complicated by the various states of decomposition of the country rock of the deposits in which many of the ores occur. The problem the authors attempted to solve arose from a request to float an impure magnesite containing varying proportions of siliceous gangue with calcium carbonate. The ore is normally enclosed in serpentine masses, somewhat decomposed, and in mining it wall rock is incidentally added, so that variable amounts of siliceous material occur in the samples. The silica, alumina, and iron oxide are so closely associated with the magnesium carbonate in the magnesite that ordinary mechanical separation at coarse mesh sizes is of no avail. It is well known that calcium carbonate can be floated by suitable reagents, therefore it seemed reasonable to suppose that magnesium carbonate minerals would behave in a similar manner, but experimental trial proved that this supposition was unfounded. Therefore the first step in the problem was to find out what differences of behavior there were between magnesium and calcium carbonates under flotation conditions, or when suspended in water. In water at 18" C. magnesium carbonate is slightly more soluble than calcium carbonate; in fact, MgCO3 is soluble to the extent of 0.0106 grams in 100 c.c. of water at 18" C. and CaCO3 to the extent of 0.0013 grams. However, magnesium carbonate in water gradually changes to the basic carbonates of a composition (3MgCO3.Mg(OH)23H2O) or (4MgCO3.Mg(OH)25H2O), depending upon conditions, and calcium carbonate to calcium hydroxide, Ca(OH)2. The relative solubilities of these hydroxides in water are the reverse of the solubilities of magnesium and calcium carbonates. The range in published figures for solubility

Jan 1, 1938

By S. D. Michaelson, Eric Sinkinson

Many of the magnesite ores of the western part of the United States contain such large amounts of silica and hydrous silicate minerals that the value of the ores is either low or nominal. Expensive and carefully controlled mining methods are necessary to prevent excessive dilution of the higher grade ores by introduction in mining of small pieces of the hanging walls or footwalls of the deposit. This difficulty is further complicated by the various states of decomposition of the country rock of the deposits in which many of the ores occur. The problem the authors attempted to solve arose from a request to float an impure magnesite containing varying proportions of siliceous gangue with calcium carbonate. The ore is normally enclosed in serpentine masses, somewhat decomposed, and in mining it wall rock is incidentally added, so that variable amounts of siliceous material occur in the samples. The silica, alumina, and iron oxide are so closely associated with the magnesium carbonate in the magnesite that ordinary mechanical separation at coarse mesh sizes is of no avail. It is well known that calcium carbonate can be floated by suitable reagents, therefore it seemed reasonable to suppose that magnesium carbonate minerals would behave in a similar manner, but experimental trial proved that this supposition was unfounded. Therefore the first step in the problem was to find out what differences of behavior there were between magnesium and calcium carbonates under flotation conditions, or when suspended in water. In water at 18" C. magnesium carbonate is slightly more soluble than calcium carbonate; in fact, MgCO3 is soluble to the extent of 0.0106 grams in 100 c.c. of water at 18" C. and CaCO3 to the extent of 0.0013 grams. However, magnesium carbonate in water gradually changes to the basic carbonates of a composition (3MgCO3.Mg(OH)23H2O) or (4MgCO3.Mg(OH)25H2O), depending upon conditions, and calcium carbonate to calcium hydroxide, Ca(OH)2. The relative solubilities of these hydroxides in water are the reverse of the solubilities of magnesium and calcium carbonates. The range in published figures for solubility

Jan 1, 1938

By W. A. Wall, R. L. Kidd

IN present-day flotation practice, grinding of the flotation feed is carried to extremely fine sizes, 70 to 80 per cent minus 200 mesh being customary. The greatest flotation losses occur in the coarsest and finest sizes, but the losses in the very fine sizes are, of course, much the more important because of the large proportion of fines in the feed. These losses are particularly high in zinc ores so a study of the effect of size on the flotation of sphalerite has been made. The mineral used in these experi¬ments was a pure sphalerite, especially free from copper, from the Joplin district in Missouri. The sizes coarser than 200 mesh were separated by screening, the sized mineral then being deslimed on a Wilfley table. The sizes finer than 200 mesh were obtained by water elutriation as described by H. R. Bradford (M. S. Thesis, University of Utah, 1932) ; particles finer than 6.5 microns could not be obtained with the apparatus used.

Jan 1, 1933

By S. S. Arentz

An organized safety program has reduced accidents at Pioche because effort is first devoted to arousing and maintaining interest in safety, followed by training in accident prevention, assigning responsibility for the detection and removal of safety hazards, and finally, by keeping score through an adequate system of records. A health program is intergrated with the safety program.

Jan 1, 1950

By AIME AIME

THE meeting" of the Rare Minerals and Metals Committee was held Monday afternoon, Feb. 17; Donald M. Lidclell, chairman, presiding. The first paper (T. P. 279), "Progress in the Use of Tantalum," by George W. Sears, was read by Mr. Smyth. Dr. Sears' paper contains an interesting summary of the uses, alloys and ores of tantalum and a resume of present method of reduction. The uses of tantalum is based on its extreme rise to the reaction of even the strong mineral acids, its great avidity for the common gases and its capacity for transforming alternating to direct current. Tantalum, as an alloy material, has received considerable study and many alloys have been reported. Among them three types appear to .be most prominent, alloys of high melting point, hard alloys and acid rising alloys. As the estimated quantity of tantalum in the earth's crust is less than that of gold, it must be looked upon as n rare metal. Australia is the greatest producer and the Black Hills of South Dakota produce minor amounts. As the one type of mineral available contains both tantalum and columbium, the extracting and metallurgy of tantalum are difficult chemical processes. Greater simplicity in this and the development of a market for columbium would undoubtedly be of great benefit to the tantalum industry, andl make for a greater use of tantalum produced.

Jan 1, 1930

By PHILIP N. MOORE

IT is a pleasure to realize even at that day the dignity of the engineer's calling was upheld. May I also add my firm belief that today there be many engineers who will qualify to the specifications of our interesting author. Since that time, the development of the world has been chiefly due to the engineer, and so far as human brain can foresee, the material tasks of the future will continue to follow the directions of his judgment. Popular opinion says this is the age of the engineer; literature, which in the long run, voices public sentiment, shows it in the number of engineers who figure as characters of fiction. The engineer has been doing the big things necessary to increase the comfort and efficiency of mankind, but while a certain amount of fame and repute falls to him, too often he figures as the hired man of the entrepreneur, using that term not in the offensive sense of a mere promoter, but to mean the great visioned master of enterprise who has seen ahead of other men, recognized the coming needs of the world, and through ability to inspire others and to hire capital for his use has also been able to hire engineers as needed. Justly enough, therefore, to such men comes the fame as well as the prize of the game.

Jan 1, 1926

By Abdul-Fattah K. Kaddou, P. C. Rosenthal

THE authors have studied the problem of temper brittleness in steel1 employing an internal friction method. The specimens are in the form of wire, 14 B and S gage (0.064 in diam), 6 in. long. It was very desirable to have an apparatus to test the wire specimens for temper brittleness without making standard notched-bar Izod or Charpy impact tests. Such a device would have two favorable advantages: the first is that no standard impact specimen would be necessary, thus saving time and labor; the second is that there would be a direct correlation with internal friction results, thus eliminating the size factor if standard impact specimens had to be used. A search was made without result to find a commercial apparatus for this purpose. The literature was surveyed to investigate if such a test had been utilized. No such work has been reported in the literature; however, zapffe2 has described an apparatus used for testing for hydrogen embrittlement in

Jan 1, 1961