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By Roy P. Hudson

A micropyrometer known as the De Graaf apparatus has several advantages over the gas-furnace method for determining ash fusibility. When the De Graaf apparatus is operated by a modified method of procedure, the results closely check those of the gas-furnace method. This is indicated by tests on 27 samples of coal ash, with an extreme variation in fusibility values of 654" F. However, most of the ashes fused at temperatures between 2300º and 2500º. This, presumably, is the temperature interval within which the micropyrometer gives the best results. Additional comparisons are desirable. DISCUSSION (Thomas G. Fear presiding) A. C. FIELDNER,† Washington, D. C. (written discussion‡).-—The Pittsburgh Experiment Station of the Bureau of Mines has made two investigations1 of the micropyrometer for determining the fusibility of coal ash. These studies were undertaken with a view to adopting the micropyrometer method us a substitute or alternate to the present standard gas-furnace method, in view of the obvious advantages of greater speed, smaller ash sample, smaller laboratory space requirements, less equipment and greater comfort to the operator. However, the investigation showed that the micropyrometer type of furnace as then operated in five laboratories having this equipment could not be accepted as an alternate to the standard gas furnace, which is capable of close duplication in different laboratories, as shown in a recent colmparison between the Pittsburgh Experiment Station of the United States Bureau of Mines and the Fuel Research Station of Great Britain.2 The algebraic meau

Jan 1, 1934

By W. E. C. Coxe

Many of you who are interested in the manufacture of iron and steel, have no doubt heard of the "Wheeler process for combining iron and steel." Mr. Wheeler has formed a company, styled the "Combination Trust Company," whose business is to grant licenses for the use of this patent process in producing what he calls "iron-clad steel." It has been proposed to apply it in the manufacture of car or wagon axles, also to shafting, having steel cores or centres covered with iron; to tubes of steel with an inner and outer skin of iron ; to structural purposes, such as girders and beams; bridge and tie-bolts, where the strength of the iron and the rigidity of the steel would be desirable. In answer to a request from Mr. Wheeler, permission mas accorded him to make some experiments at the rolling mill of the Philadelphia and Reading Coal and Iron Company, at Reading, Pennsylvania, with a view to manufacturing some steel-headed rails. In making this kind of a rail two difficulties are encountered. If the iron is brought to the requisite heat to weld properly, the steel is likely to be burned; if the steel is cared for, to prevent burning, the several layers of iron are not brought up to the proper welding heat. Mr. Wheeler claimed that the steel slab covered with iron which he furnished for the head of the rail could net be injured by any heat to which it might be subjected in the ordinary course of heating the rail-pile. He claimed, also, that by this method the porosity, which he thought was characteristic of all solid rails of Bessemer steel, would be overcome. Four steel slabs were furnished for this experiment, being Bessemer steel of .61 carbon, made at the Edgar Thomson Steel Works, and covered with iron in one of the Pittsburgh mills. The slabs were in section seven inches wide by three inches thick, and the iron covering was one-eighth to three-sixteenths inch thick. Each slab was placed on a pile of iron made up in the ordinary way for a rail fifty-six pounds per yard and thirty feet long. The heating was under the personal direction of Mr. Wheeler, and

Jan 1, 1879

By Frank Clowes

This lamp has been devised to burn oil from a flat wick in the usual way for lighting-purposes ; and also to burn a hydrogen-flame of standard size instead of the oil-flame, when delicate and accurate gas-testing is to be carried out. The change from the oil-flame to the hydrogen-flame, and vice versa, can be made with great rapidity, and without opening the lamp or running any risk in the presence of gas. The oil-flame serves for illumination; and when the wick is drawn down by the " pricker," so as to abolish the light, the pale blue reduced oil-flame serves to detect fire-damp or "gas," in any propor

Jan 1, 1894

By Charles H. Snow

In vol. xxxviii. (1889) of the American Journal of Science, under the heading " Pseudomorphs of Native Copper after Azurite from Grant County, New Mexico," Mr. W. S. Yeates describes a most interesting mineral form. His account is, that a material having the appearance of native copper, but brittle and much lighter than native copper (its specific gravity being but 4.15), was submitted to him by the United States National Museum for examination. The substance was reported to him as occurring in masses, varying in weight from one ounce to seventy pounds, and composed of tabular crystals, variously grouped. The specimens, when submitted, ex hibited on the outride a covering of clay; and they were subse quently found to consist of particles of the same clay, intimately mixed with others of native copper, producing the aspect, without the weight, of pure copper. The forms of the azurite crystals, found at Bisbee, Arizona, having been suggested by the specimens, actual goniometer-measurements were made; and the two crystallizations were thus proved to be identical. To these statements I may be permitted to add some further in formation, derived from personal examination, and illustrated with a suite of characteristic specimens collected by myself (Fig. 2).* Grant County, New Mexico, in which these specimens were found, is a region noted for variety of mineral species. The sixth edition of Dana's Mineralogy mentions many of the silver, copper, and lead minerals, and also turquois, aragonite, wulfenite, barite, fluorite, vanadinite, etc. I have noticed also green and red garnet, molybdenite, native alum, smithsonite, bornite, etc., some of which presented peculiar modes of occurrence. The green garnet, for instance, was in masses formed of separate crystals, each of pea-size and not unlike that vegetable in tint and smooth opaqueness. The crystallization was

Jan 1, 1893

By L. G. Austin

If S (x) is the specific rate of breakage of size x and B (x, y) (see Table 1 for Nomenclature) is the cumulative breakage distribution function, the Herbst Fuerstenau2 assumption is that Inserting this assumption into first-order grinding equations it has been shown" that there are then simple analytical solutions to the grinding equations, as shown in Table 2. In this context "plug flow" is defined as all material passing through the mill in the same length of time, the residence time t. The term "n fully-mixed" means that the mill has a residence time distribution" which can be treated as if the mill were n equal fully mixed sections in series. In addition it has been shown that the assumption of Eq. 1 also leads to simple analytical solutions for closed-circuit, steady-state grinding with an ideal classifier at the mill exit returning oversize to the mill feed. The solutions are also given in Table 2, with µ as the ideal classifier cut size, C the circulation ratio, and Q (x) the size distribution of the circuit product. The specific surface area of these size distributions is where the density-shape factor k. is assumed to be constant with size. In practice, most methods of size analysis or area [ ] measurement have a finite lower limit, so that the integration is really performed from xm, to xm, For a realistic degree of grinding the value of So is dominated by the fine sizes because of the 1/x factor. Consider batch grinding of a feed of size y to y + dy. The batch grinding solution given in Table 2 is then [ ] The fresh surface area produced is the area of the fines plus the area of the original material remaining minus the area of the original material, [ ] Little error is introduced by neglecting the last term on the right-hand side since at t = 0 it is zero, and when t is significant the first term dominates because of the fine sizes produced. In addition, the form of P (x, t) for [ ] realistic values of S (x) 2t ax° is such that the major fraction of fresh surface produced is contained within the bottom 10% of weight of broken material, that is, for sizes for which P(x, t) < 0.1 (providing y is not near x.,). Thus for surface area purposes Eq. 3 can be approximated by [ ] becomes providing again that the feed sizes are coarse relative to xmi. Then the fresh area production is and W is the mass in the mill. The rate of surface production is WK, and the specific surface is Kt. From Table 2, the specific energy is mt/W so surface production per unit energy is [ ] Surface produced per unit energy input = KW/m (8) where m is the energy input of the mill. Clearly, identical reasoning applies to open-cycle, plug-flow grinding, with t replacing t, and Eq. 8 is obtained again. Considering open-cycle, fully mixed grinding, similar reasoning gives P(x) - t S(x) for surface area purposes, and

Jan 1, 1974

By R. M. Rose, D. P. Ferriss, J. Wulff

The effect of orientation on the stresses, nctivation energies, and activation volumes for yielding and plastic flow of tungsten single crystals was investigated. Tensile tests showed the proportional limit to be a function of orientation: crystals whose tensile axes were near the [I10} direction were roughly three times as strong as [loo] crystals. The [ 1101 crystals showed low strain hardening and displayed yield phenomena, whereas the other orientations yielded smoothly and showed considerable strain hardening. The fracture mode was cleavage, except for crystals near the [1101 , many of which gave "chisel" fractures at 300°and 373°K. The activation energy for yielding was approximately one- half an electron; volt at all orientations, and the volume of activation was (12 to 14)b3, except near the [1101, where it was 7b3. Activation volumes generally increased after yielding. The most common theoretical models for yielding and strain hardening of bcc metals were. found to be insufficient to the intepretation of the observations here in. An explanation is proposed, based on the dislocation reaction dislocation networks and jogs, md jogs formed during plus tic flow. PRECLSE knowledge of the Drocesses involved in the yielding and plastic flow of the refractory metals is essential to the formulation of models for their flow and fracture. Despite this need, the single -crystal investigations, especially of tungsten, have been sparse. Slip occurs at low temperature, according to schadler,i in <111> directions on {110) planes; as the temperature rises to room tempera-

Jan 1, 1962

By R. W. Raymond

ALL history testifies that the mineral resources of a region have furnished both the impulse for its first development by man, and the foundation for its subsequent occupation by civilized and prosperous communities. In the pre-historic ages, the hunters, fishers, shepherds and gardeners of the world may have wandered or tarried without regard to the attractions of the mineral deposits which they could not utilize, and therefore did not value. But with the rise of civilization, as expressed in manufactures and commerce, the national value of such deposits began to be realized. Barbarous and remote tribes, possessing the sources of such supplies, won recognition in trade long before they could attain it through any other means. Thus, the North American Indians of Lake Superior exchanged their native copper for the mica of North Carolina; the ships of Tyre sailed all the way to Spain for lead and to Britain for tin; and the fleets of Solomon brought gold from Tarshish. In more modern times it has been chiefly the precious metals that have stimulated exploration and conquest. The inherent qualities and the traditional value of gold and silver sufficiently explain this historic fact, the continued existence and potency of which is evidenced, even in our own times, by the occasional rush of eager adventurers to new districts where gold and silver have been discovered. The history of North and South America has been peculiarly influenced by this factor. It was the prospect of obtaining gold and silver that led the Spanish adventurers to the shores of America, and the conquests of Mexico by Cortez and of Peru by Pizarro were inspired by the stories of the wealth of the Aztecs and the

Mar 1, 1909

Extremes in temperature and weather, along with the highly corrosive nature of acid leach solutions used at open-pit copper mines, necessitates the use of pipeline systems that are both corrosion resistant and impervious to the environment.

Jan 6, 1976

By George E. Aiken

Modern high speed bucket wheel excavators (BWEs) can dig materials which power shovels can&apos;t handle without blasting. Yet these machines are not used in any large, open pit ore mines in the United States. American mining has been slow to use the wheel&apos;s special capabilities of high production volume at low cost, due perhaps to a traditional familiarity with shovels and draglines and/or the lack of data of BWE operation, design and cost. Of course, shovels and draglines can not be replaced by BWEs in all cases, but under suitable conditions bucket wheels can out-perform other conventional excavators and simultaneously permit significant operating savings. The latter aspect will become increasingly important to American mining men because as more low to medium grade orebodies are found in regions of thick overburden, better and cheaper ways of uncovering them must be developed. Typical of such areas are the thick alluvial fans of the Southwest and the glacial drift areas in northern regions. Much of this material would handle well with a wheel excavator without blasting, although ripping might be necessary in some cases.

Jan 1, 1966

Jan 1, 1932

By Oswald J. Heinrich

AT the Baltimore meeting of the Institute in February, 1879, Mr. Eckley B. Coxe, then president of the Institute, called attention in his address to the subject of Secondary Technical Education, and

Jan 1, 1881

By R. W. Marrs

Kimberlite contains a unique assemblage of minerals and exhibits a characteristic pattern of spectral reflectance in the visible and near-infrared wavelength region. This spectral pattern is readily discerned in well exposed kimberlite outcrops, but becomes increasingly difficult to identify when outcrops are partially covered by vegetation or soils derived from nonkimberlitic materials. Detection of poorly exposed kimberlite diatremes is possible using multispectral imaging techniques where spectral bands are chosen to optimize contrast between the kimberlitic soils, nonkimberlitic soils, and vegetation. Careful processing of the multispectral data is essential to separate the spectral signature of kimberlite from the signatures of other components of the scene.

Jan 1, 1986

By Lawrence A. Roe

Talc, when it can be isolated as a pure mineral, has a composition of 63.36% SiO2, 31.89% MgO, and 4.75% H2O. However, as an industrial commodity, talc rarely approaches theoretical purity. Nevertheless, the impure talc products of commerce find a multitude of uses and few substitutes in many industrial applications. Minerals commonly associated with and sold together in talcose mixtures are tremolite, chlorite, dolomite, mica, and magnesite. Steatite was originally a mineralogical name applied to pure talc. In today&apos;s commerce steatite generally refers to the massive variety of talc suitable for electrical insulator manufacture. Block steatite ore can be machined into various shapes. Impure varieties of massive or block talc are still commonly referred to as soapstone. Soft massive talc, suitable for crayon manufacture, has been referred to as French chalk. It has been common practice to discuss talc, soapstone, and pyrophyllite under the same general heading. In the case of soapstone and talc, this is a natural thing since many different types of platy, soft minerals exhibiting a high degree of lubricity (commonly referred to as "slip") have been grouped together and called soapstone or talc. Further, there is a mineralogical relationship of pyrophyllite to montmorillonite and talc to hectorite. Thus, talc and pyrophyllite are sometimes referred to as clay minerals. When finely divided talc or pyrophyllite are combined with water in proportions to make a slurry, the end product does have the appearance of a clay-water mixture. Soapstone for utensils and ornaments was mined by prehistoric Indians on Santa Catalina Island, Calif. In the mid-1800s, soapstone from deposits along the western foothills of the Sierra Nevada mountains was used by white settlers for building and ornamental stone and in the linings and foundations of furnaces (Anon. 1956). Previous to 1916, the annual recorded production in California did not exceed 2000 tons. In the period 1912 to 1918, output rose sharply when the Talc City, Western, and Silver Lake mines were put into operation. From 1916 to 1935, the state&apos;s annual output of talc was in the range of 9,000 to 20,000 tons. In the mid-1930s, the use of talc in wall tile grew rapidly. In California, the production of talc grew to 63,000 tpy in 1943. The post-war building boom helped California production to grow to 120,000 tons in 1951. In 1968, production was 165,000 tons, 1969 was 145,000 tons, 1970 was 185,000 tons, and 1972 was 155,000 tons. Talc mining in New York state dates to about 1878 when a Colonel Palmer and associates opened the first commercial talc mine on the Nelson Freeman farm near Talcville, New York. In 1893, this operation was sold to the International Pulp Co. which changed its name to the International Talc Co. in 1944. Total production from seven New York mines, in 1948, was 130,000 tons. A new talc operation, the Gouverneur Talc Co. owned by the R.T. Vanderbilt Co., began operations near Balmat, N.Y., in 1948. The initial capacity of the processing plant was 200 tpd (Gillingham, 1950). Subsequent expansions have increased capacity to over 600 tpd. The Vermont talc industry began just after the start of the 20th century. Talc was discovered in the area of the present Johnson, Vt., talc mine in 1902. The American Min¬erals Co. initiated plant operations at Johnson in 1904. The Magnesia Talc Co. opened a plant at Waterbury, Vt., in 1913 (Burmeister, 1963; Trauffer, 1964) and acquired American Minerals Co. in 1923. The Waterbury mine has a long history as a producer of talc crayons. The Eastern Magnesia Talc Co. was formed in 1924 by a merger of the Eastern Talc Co.

Jan 1, 1975

By F. D. Delve

RECENT studies by the author on the reduction of titanium from TiO2-bearing slags have been accompanied by difficulties that are attributed to

Jan 1, 1959

By WILLIAM E. NEWNAM

THE molding and loading of pig lead has, in the past, been accomplished mainly by the strong arm method and, as the pigs are usually loaded directly into the cars, it has been a hot and laborious task. Of late years it has been difficult to obtain men willing to perform such labor and the need has been felt for loading and molding machinery which would eliminate all manual handling of the hot pigs and which would be sufficiently compact to permit of installation in existing plants with little or no

Jan 1, 1924

Jan 1, 1932

By E. Miller, N. Chou, K. Komarek

The solid solubilities of the compounds PbS, PbSe, and PbTe have been determined by equilibrating single crystals with two phase alloys. The solubilities were determined by measuring the Hall coefficient of the equilibrated samples. The observed maximum deviations from stoichiometry on the lead rich and the chalcogen-rich side of the phase fields were: at. pct excess Pb at pct excess S at 850°C; PbSe--4 x 10&apos;" at. pct excess Pb at at. pct excess at 800°C; and PbTe-2.8 x 10 4 at. pct excess Pb at 780°C, 10"1 at. pct excess Te at 720°C. The previously developed theory of retrograde solubility has been expanded to include intrinsic disorder in the compounds, and the experimental results are in agreement with the theory. THE solid solubility limits of intermetallic semiconducting compounds are of considerable interest, since many of these compounds have potential use as thermoelements in thermoelectric devices, as infrared detectors, or in semiconductor devices. The solidus curves of a significant number of these compounds have been reported to be retrograde with the maximum solid solubility occurring between the eu-tectic and the maximum melting temperatures. In a previous paper,&apos; equations were derived which permit calculation of the maximum solid solubility of an AB compound exhibiting retrograde solubility. Derivation of these equations was based on the assumption that the compound is a nondegenerate semiconductor at the temperature under consideration, that the defects were unassociated, and that the vibrational contribution to the entropy of the compound could be evaluated by the Einstein approximation. It was shown that at the temperature of the maximum solid solubility The entropy term ASS is composed of the entropy of formation of the solid stoichiometric compound (AS$)*, and the entropy due to deviations from stoichiometric composition which is the sum of a con-figurational term (aS*), a vibrational term (AS,), and an electronic term (AS,). In the previous paper the positional entropy was evaluated considering the con- N. CHOU, Member AIME, formerly Graduate Student, New York University, N. Y., is with IBM, Yorktown Heights, N. Y. K. L. KOMAREK, Member AIME, formerly with New York University, is Professor, Department of Inorganic Chemistry, University of Vienna, Vienna, Austria. E. MI LLER, Member AIME, formerly with New York University, is Associate Professor of Mechanical Engineering, California State College at Long Beach, Calif. The paper is based on a thesis submitted by N. CHOU to the Graduate Division, School of Engineering and Science, New York University, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Materials Science. tributions from defects arising from deviations from stoichiometric composition. The derivation is generalized in the appendix to include intrinsic disorder. The electronic entropy term is also recalculated in the appendix. Of the various semiconducting compounds, the solidus curves of Pbs,&apos; and ~b~e,~ have been most extensively studied. The solidus of PbSe has also been determined, but the temperature of maximum solubility has not been accurately established.5129 The present investigation was undertaken to compare the experimental solid solubility data for these systems with the values predicted theoretically. Since the temperature and composition of the maximum solubility of PbSe has not been accurately determined, experimental emphasis was placed on determining the solidus curves for PbSe in the region of maximum solubility, although experiments were also performed on PbS and PbTe at several temperatures. X-ray diffraction studies were also made on carefully prepared powder samples of PbSe to determine the variation of lattice parameter with composition. EXPERIMENTAL PROCEDURE The procedure of Brebrick and Allgaier was employed for determining the solidus data. Monocrystal-

Jan 1, 1970

By EUGENE MCAULIFE

Jan 1, 1934

Jan 1, 1932

By W. S. Ayres

The protractor here to be described embodies several important improvements that have been suggested by the use of other protractors and by observing the errors occurring in practice with them. It is more particularly an improvement

Jan 1, 1896