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By Charles H. Addison, Robert W. Shields, James W. Sweeney

GIPSY: Is user oriented. Is flexible in applications. Is an ITERATIVE question answering system. Has an adaptable retrieval mechanism. Has both a batch and a teleprocessing version. Allows the user to "browse" through his information. Has ability to answer "ad hoc" queries. Is a currently working and proven system.

Jan 1, 1969

By Willy Ank de Morais

Para se determinar as propriedades mecânicas de uma junta soldada torna-se necessário conhecer as propriedades mecânicas do metal de adição decorrente de um processo de soldagem. O objetivo desse trabalho foi verificar as propriedades mecânicas de uma solda MAG elaborando e qualificando um procedimento de soldagem. Para isso foi utilizado quatro ensaios mecânicos: tração, macrográfia, micrografia e dureza. Foi estipulado o limite de escoamento, de ruptura, o alongamento e a estricção; macrográfico, determinou-se, a olho nu, a zona fundida, a zona de ligação, a zona termicamente afetada e o metal de base; micrográfico, tração, definiu-se os componentes microestruturais da solda e do metal de base; dureza e foi estabelecida a tenacidade da solda e do metal de base.

Aug 16, 2017

By C. A. Hartnagel

During- the past 10 years the annual production of petroleum in New York has averaged close to 5,000,000 bbl., the total for the period being 49,881,000 bbl. In 6 of the 10 years, the production was slightly in excess of the 5,000,000 mark. The 1944 production of 4,697,000 bbl. represents a 7 per cent decline from the previous year. Of the total 1944 output, the Allegany County district, which includes two small areas of Steuben County, contributcd 3,614,065 bbl., a decline of 5 per cent from 1943, and the contribution of Cattaraugus County, which represents the northern extension of the Bradford pool of Pennsylvania into New York was 1,082,935 bbl., a decline of more than 14 per cent. Since March 1942, the posted price of New York crude oil has remained at $3.00 per bbl. On lug. I, 1944, a Federal subsidy of 75¢ per bbl. was granted to oil producers, thus making the price actually $3.75 per bbl. Since all of the oil produced in New York comes under the designation "stripper well operations," it is entitled to the Federal subsidy. During the last few years there has been little change in the number of wells drilled annually. In the Allegany field, which accounts for three fourths of the oil produced in the state, 1240 wells, including water-intake wells, were drilled during 1944 as compared with 1223 in 1943. There was no marked increase in the number of wells drilled after granting the subsidy of 75¢ per bbl. of oil on Aug. I, the increase being but 14 wells during the last half of the year over the preceding six months. In flooding operations it is not to be expected that even a substantial increase in the price of crude oil will be reflected quickly in an increase of the number of wells drilled or in a marked increase in production of crude oil. In flooded areas, oil is obtained through a program extending over a number of years. This program involves the drilling of the water or input pressure wells, drilling of the oil wells, building up the oil flood to maximum production, and finally the watering out of the well when the amount of oil produced in proportion to the water becomes so small that pumping is no longer profitable. The various operations may extend over a period of 10 years or more, during which time the price of crude may have fluctuated greatly. Although the rate of production can be controlled to a limited extent, it is evident that a flood when once begun must be continued regardless of the price of crude. During the past seven years New York crude has had a price range from $1.68 per bbl. in 1938 to the present price of $3.75 per barrel The field pattern now in general use for wells in a flood project is the "five-spot." Under this arrangement, the lease is divided into squares with a water well at each corner and an oil well in the center. In the all-over pattern of the lease each oil well is acted upon by four water wells and each water well supplies part of the pressure to four oil wells. Spacing between the input water wells and the oil wells usually varies from zoo to 225 ft. or, on an acre basis, there is one oil well and one water well for each 2 1/2 acres. In recent years there has been a tendency to increase

Jan 1, 1945

By Frank J.

The increased demand for aluminum for military purposes during World War II necessitated the development of domestic deposits of alumina-bearing ores. Kaolin, siliceous bauxites, anorthosite, and diaspore-containing clays have been investigated and studied in the laboratory and pilot plant. The Bureau of Mines is preparing a series of reports covering investigations of these ores. The tests contained in this report are restricted to sintering and leaching tests on kaolin from South Carolina, where extensive deposits were proved to exist. The leach liquors were found to have substantially the same composition as those produced from the diaspore-containing clays, and therefore it would be expected that no difficulty would be experienced in producing calcined alumina of relatively coarse particle size and with other properties conforming to the specifications for metallurgical-grade alumina.

May 1, 1947

By R. S. Rickard, H. D. Peterson, J. D. Miller, M. C. Fuerstenan

Pure chrysocolla is floated with chelating agents that form insoluble complexes with copper at ambient temperature. Complete flotation is obtained with potassium octyl hydroxamate as collector at pH 6. Flotation response is enhanced with increased temperature when low additions of hydroxamate are involved. A natural ore was floated with 0.4 1b per ton octyl hydroxamate at pH 6.5 and 58°C, and a flotation recovery of 76% was obtained with a concentrate grade of 31.6% copper. The flotation characteristics of the oxide copper minerals, malachite, azurite, and cuprite, have not presented the difficulty for concentration as have those of the copper silicate, chrysocolla. The copper carbonates and oxides respond reasonably well to flotation with conventional collectors, whereas chrysocolla will not respond to flotation with fatty acids or xanthates under normal flotation conditions. In this view then, other reagents will have to be devised to function as collectors for chrysocolla. The most obvious general class of reagents for this purpose would seem to be the organic copper chelating compounds. The utility of chelating agents as collectors in flotation systems has already been demonstrated. For example Vivian1 has floated cassiterite using ammonium nitrosophenylhydroxylamine. Holman2 studied the flotation of nickel oxide ores with dimethylglyoxime and also suggested the use of taurine on oxidized lead ores. A rather detailed study on the application of certain chelating agents to some flotation systems was presented by Gutzeit.3 This work indicated that the formation of surface insoluble chelates is probably responsible for flotation in many cases. The role that soluble chelating agents assume was also presented, that is with effective removal of polyvalent cations by complex formation, effective depression of quartz can be obtained. DeWitt and Batchelder4,5 have shown that oximes function well as collectors for chalcocite, malachite, azurite, and cuprite. Ludt and DeWitt6 have presented the possibility of using dyes, such as octyl malachite green, as a collector for chrysocolla. These works presented by DeWitt et al suggest that organic copper chelating compounds offer considerable promise for concentrating chrysocolla, but that the most suitable chelating reagent from the standpoint of cost and flotation response has yet to be determined. The present investigation was undertaken to study the flotation response of chrysocolla to selected copper chelating compounds, that is ethylenediamine, hexamethylenetetramine, potassium octyl hydroxamate, dimethylglyoxime, and benzoin a-oxime. EXPERIMENTAL MATERIALS Chrysocolla: The chrysocolla used in the microflo-tation studies was from New Mexico and analyzed 20.8% copper. X-ray diffraction showed this material to be amorphous in character, but some faint lines of quartz were noted. A natural oxide copper ore from Utah was also used in the investigation. This ore contains malachite principally but also contains chrysocolla and tenorite together with some sulfide copper. The sulfide copper comprises from 15 to 20% of the total copper content of the ore. Water: Conductivity water was used in the microflo-tation experiments, while Golden tap water was used in the experiments with the natural ore. Reagents: Reagent grade n-amyl alcohol was used as frother in the experiments with pure mineral, while MIBC was used in the work with the ore. Ethylenediamine, hexamethylenetetramine, dimethylglyoxime and benzoin a-oxime were reagent grade in quality. Pure potassium octyl hydroxamate was prepared as follows: 1) 1.0 mole of KOH in 140 cc of methanol was combined with 0.6 mole of hydroxyl-amine hydrochloride in 240 cc of methanol at 40°C (KC1 precipitates under these conditions and to effect complete removal of KCl, the system was cooled to 10°C and filtered), 2) a light methanol wash was then given the KC1 cake, 3) the filtrate was agitated at room temperature and 0.33 mole of the methyl ester of the organic acid (i.e. methyl octanoate) was

Jan 1, 1965

By Mark R. Bowie

Air-fall tuffs have been altered to zeolite via reaction of volcanic glass with local pore solutions at the six localities discussed in this paper. These are in the southern Basin and Range Province of Arizona and New Mexico, and in the Trans-Pecos and Coastal Plain regions of Texas. Zeolitization occurred in either closed- hydrologic, open-hydrologic, or hydrothermal groundwater systems. The tripping Spring Valley (DSV) chabazite in Arizona and the Buckhorn clinoptilolite in New Mexico originated in a late Cenozoic network of closed-hydrologic, lacustrine basins extending from southeast Arizona into southwest New Mexico. At DSV, two potentially commercial chabazite-rich tuffs are interbedded with lacustine mudstone. The main zeolite tuft contains up to 90 percent chabazite. The upper zeolite tuff averages approximately 67 precent chabazite. At the Buckhorn deposit, two clinoptilolite-rich tuffs are interbedded with lacustrine m udstone in the upper part of the Gila Conglomerate. The lower zeolite tuff contains up to 90 percent clinoptilolite. The upper zeolite tuff contains over 60 percent clinoptilolite. The Casa Piedra clinoptilolite is in the Trans-Pecos region of Texas. It formed during the Tertiary in a closed basin containing a playa lake. The Casa Piedra tuff averages about 60 percent clinoptilolite. Air-fall tuffs of the Cuchillo Negro, New Mexico and Tilden, Texas clinoptilolite deposits were zeolitically altered by either percolating ground waters in open-hydrologic systems or locally by ponded, saline, alkaline solutions. Cuchillo Negro tuffs are Tertiary and average approximately 50 percent clinoptilolite. Clinoptilolite-rich tuffs of Ebcene age have been mined from four quarries at the Tilden deposits. Tufts from the Kuykendall and Buck Martin quarries contain approximately 50 to 60 percent clinoptilolite. Low temperature, SiO2 - rich, hydrothermal solutions altered air-fall tuff to clinoptilolite and chabazite in the Foster Canyon area of the Tertiary Cedar Hills and Seldon Hills volcanic-vent zone in southcentral New Mexico. Poster Canyon tuffs contain up to 60 percent zeolite and average 40 to 50 percent clinoptilolite. The dominant mineral in the zeolite tufts at the six deposits studied is generally microcrystalline and either chabazite or clinoptilolite. Lithic fragments, unaltered volcanic glass, other zeolites, quartz, calcite, opal-CT, cristobalite, feldspar, evaporites, clays, and mafic minerals are also constituents of the tufts.

Jan 1, 1987

Numerical simulation by a finite element computer code has bee* used to identify key stages in the initiation of confined bulk explosive by cast primers. The simulations have been verified by comparison with experimental field measurements of shock arrival time versus distance above the primer for a relatively sensitive emulsion doped with ammonium nitrate prills. Further simulations were performed examining the effect of primer size in a relatively insensitive blend of ANFO and emulsion. Immediately above the primers, changes in shock velocity in the explosive were caused by the interactions between shocks originating from different surfaces of the cylindrical primers. At a distance up the explosive column corresponding to about one to two borehole diameters, the arrival of shock reflections off the borehole walls caused a sudden acceleration up to the confined steady state detonation velocity. The simulations reproduced experimental observations that primer size has only a weak effect on changes of shock velocity with distance for confined explosives. However, it was predicted that primer size has a strong influence on the intensity and duration of the pressure pulses that bulk explosive send into the rock surrounding the primer region.

Jan 1, 1990

By M. Moss Stanley, Ronald P. Klepper

The objective of this chapter is to provide data that will assist in the selection and sizing of equipment utilized in the filtration method of separating solids from liquids. It should be recognized at the outset that in some situations more than one option may be available to achieve the target desired. In some cases purely technical objectives may be sacrificed because of cost considerations, design factors or other elements in order to satisfy optimization within the flowsheet and/or to provide bottom line results. Before considering available options, and prior to the next step of sizing out the selection, the operating criteria should be set down. The test work to develop selection and sizing data will be based on this data and the final products desired. This will help to establish initial parameters. A. GENERAL DATA 1. Material to be filtered: a. Solids b. Mother liquor 2. Feed rate of slurry in GPM 3. Density of slurry: Sp. Gr. Solids 4. Slurry: Temp. pH Viscosity 5. Source and method of feed 6. Valuable product: Solids Filtrate Both 7. Details on: Volatility Toxicity Stability 8. If flocculant is indicated, what has been used? 9. Describe product: (i.e., fibrous, cor 10. rosive, abrasive, inflammable, explosive, pasty, 11. Does product alter or require special environment during transport? 12. What type of filter media has been used successfully? 13. Is there any objection to use of a filter aid? If not, is there any preference? B. SOLIDS DATA 1. Sp. Gr. Bulk density 2. Screen analysis 3. Desired percentage moisture in cake 4. Solubility (state conditions): In mother liquor In wash water 5. Description of cake: (i.e., amorphous, fibrous, crystalline, colloidal, gran¬ular, thixotropic, 6. Special requirements for moisture de¬termination? 7. Can solids be compressed during dewatering? 8. Proposed product handling 9. Subsequent thermal drying or other pro¬cedure C. FILTRATE 1. Is separation of wash water and mother liquor desirable?

Jan 1, 1986

By T. Katayanagi, J. Shimoiizaka, K. Nakatsuka

Feldspar has been separated from silica by cationic collector using hydrofluoric acid as an activator of feldspar (1,2). Recently, one of the authors developed a new flotation process separating feldspar from quartz without using hydrofluoric acid. Presently, some silica sand mills are operating to introduce this process in Japan (3). In this flotation, feldspar is floated from silica using normal alkyltri-methylene diamine acetate together with sodium petroleum sulfonate as collectors in a hydrochloric or sulfuric acid circuit of about pH 2. From fundamental studies, it was found that, though the aliphatic diamine by itself did not adsorb on feldspar sufficiently to give a satisfying flotation in acidic circuit., the adsorption of collector was promoted by the simultaneous use of petroleum sulfonate and resulted in sufficient flotation of feldspar. On the other hand, quartz did not float in this flotation process. The application of this flotation was attempted for some types of natural samples and satisfying results were obtained. Further, an example of practical plant was introduced and the advantages in the process are emphasized.

Jan 1, 1976

By Joachim Leonhardt

Hundreds ofbolt-indicators were already used successfully in the German deep hard coal-mines to increase the safety and economy. The bolt-indicator offers the simple possibility to show roof-bolt (anchor-) loads. to indicate weak points as well as to optimize the anchor density and the dimension: The bolt-indicator is mushroom shaped and consists of coated metal. It is inserted between the anchor plate and the flanged nut. The loads appearing at the anchor are transferred to the bolt- indicator and can be recognized visually at the cylindrical part by the amount of the surface coating. Examples are used to clarify the application aims, operation and usage of the bolt-indicator and its yielding advantages in practice.

Jan 1, 2001

By A. León

El objetivo del presente trabajo es describir el sistema de relleno hidraúlico en los tajeos de vetas angostas de la mina de Morococha a través del método "Arch Back". Actualmente el sistema de relleno convencional es lento, costoso y ofrece desventajas respecto del *R/H. Los objetivos del R/H son aumentar la eficacia de minado, controlar las leyes del mineral, minar los tajeos de baja ley, mejorar el sostenimiento de las cajas y la baja de costo. En este sentido, se describen las operaciones unitarias de los tajeos con R/H y se comparan con los métodos convencionales, encontrando eficiencias en los tajeos aplicados con el método Arch Back y los tajeos de vetas angostas, así como se mejora la producción y los costos de la misma.

Nov 20, 1972

By Gordon Revey

Over ten million pounds of explosives are used daily to blast rock in mines, quarries and construction projects throughout the United States. Despite the immense volume of explosives used, serious incidents involving the legal use of explosive materials are rare. Unfortunately, when incidents arise they are well publicized, whereas the great majority of blasting projects-even the most challenging ones—quietly occur without incident or public recognition. Although unfair, media coverage focuses on incidents and/or accidents, and as a result skews the public’s perceptions of our industry. These negative perceptions about blasting profoundly effect our work. Most apparent are the community groups who organize to fight blasting work. However, other impacts are more insidious and have long-term effects on our industry. For instance, planning engineers or government agencies often prohibit blasting to avoid the public’s adverse reaction or because of general fear of blasting impacts. Ironically, as regulations and specifications continue to curtail our industry, the net effect is an increase in the cost of rock excavation. As taxpayers, we suffer needlessly by paying more for government funded construction projects. As blasting professionals we are additionally penalized through loss of work.

Jan 1, 2001

By AIME AIME

THE 139th meeting of the Institute will be held Feb. 17-20, in the Engineering Societies Building, New York. The annual business meeting will be held on Feb. 18 at 10 a. m., and no technical sessions will be scheduled at that time, so that all members may participate in the election of officers, hear the presentation of the annual reports of officers and committees and discuss any matter which they may care to bring up at that time. The annual dinner will be held at the Conlmodore Hotel on the evening of Feb. 20, and the usual good time is promised. Arrangements for this and other social features of the meeting are, as usual, in hands of the New York Sec- tion, of which the chairman this year, Ralph M. Roosevelt, has a well-established reputation earned as president of the Zinc Institute, as host.

Jan 1, 1930

By Walter W. Bradley

(Three, papers included, in this discussion are classified as Mining Geology and also as one of the following-A, Metal Mining: B, Milling and Concentration: L, Geophysics. These papers are TP 2255, TP 2092 and TP 2038.) CONTENTS [PAGE Review of Fluorescence as Applied to Minerals, with Special Reference to Scheelite. (TP 1967 by J. W. VANDERWILT, Min. Tech., March 1946. Discussion by WALTER W. BRADLEY) I Geologic Interpretation of Magnetic Exploration on the Mesabi Range, Minnesota. (TP 2038 by R. B. H. JONES, Min. Tech., July 1946. Discussion by ROBERT B. SOSMAN) I A Technique for Photographing Difficult Subjects through a Petrographic Microscope. (TP 2092 by DONALD W. SCOTT, Min. Tech., Nov. 1946. Discussion by HORACE WINCHELL) 2 The Search for Concealed Deposits-a Reorientation of Philosophy. (TP 2146 by SAMUEL G. LASKY, Min. Tech., May 1947. Discussion by T. M. BRODERICK)3 Occurrence of Lead-zinc Ore at Iron King Mine, Prescott, Arizona. (TP 21 go by H. F. MILLS, Min. Tech., July 1947. Discussion by HUGH M. ROBERTS)3 Geologic Relations and New Ore Bodies of the Republic District, Washington. (TP 2197 by LAWRENCE B. WRIGHT, Min. Tech., July 1947. Discussion by AUGUSTUS LOCKE and J. A. RICHARDSON) 4 San Manuel Prospect. (TP 2255 by H. J. STEELE and G. R. RUBLY, Min. Tech., Sept. 1947. Discussion by L. KENNETH WILSON, ELDRED D. WILSON and the author) 5] Review of Fluorescence as Applied to Minerals, with Special Reference to Scheelite WALTER W. BRADLEY*-AS I recall, the first portable units for ultra-violet light of practical use with scheelite were developed at the Nevada-Massachusetts Tungsten Mine at Mill City, Nevada, and were used underground. Ultra-violet lamps are also installed there in the mill, above the gravity-concentration tables, for control observations. Geologic Interpretation of Magnetic Exploration on the Mesabi Range, Minnesota ROBERT B. SOSMAN*-When artificial precipitated magnetite is oxidized at a temperature in the vicinity of 100°C, the oxide is converted into a chocolate brown ferric oxide of the formula Fe2O3, free from ferrous iron, yet possessing the same magnetic susceptibility as the original Fe3O4. This form of Fe2O3 is variously called "ferromagnetic ferric oxide," " maghemite," or "gamma ferric oxide," and has been found as a natural mineral. If a body of magnetite in the Biwabik were to oxidize to this form, the oxidized and leached ore body might successfully conceal itself from Mr. Jones' survey by this ferromagnetic pretense. So far, gamma ferric oxide has not been found on the Minnesota iron ranges. I thought I had found some in the Hibbing pit in 1940, in a strongly magnetic specimen of soft ore differing in color from the prevailing hematite

Jan 1, 1947

By Izabelle Lannes Salgueiro Ferreira

O presente trabalho teve como objetivo adequar às propriedades mecânicas dos perfis ASTM A572 G60, através do estudo da influência dos parâmetros de processo de laminação e composição química do aço. Os perfis ASTM A572 G60, são utilizados nas indústrias de fabricação de torres de transmissão. A metodologia utilizada neste trabalho foi o desenvolvimento de um modelamento matemático, com base na ferramenta estatística de Análise de Regressão Múltipla. Através desta ferramenta foi possível obter previsibilidade de processo e identificar os parâmetros mais influentes nas propriedades mecânicas dos perfis ASTM A572 G60, o que possibilitou a determinação da composição química ideal do aço e os melhores parâmetros de processo de laminação.

Jul 30, 2018

By H. F. Silliman, Daniel R. Hull, John R. Freeman

In the normal operation of a brass-rolling mill, sheet and strip has, for the most part, been finished in comparatively thin gauges, involving a substantial amount of cold-work and a considerable number of anneals. This condition has been disturbed by the preponderance of cartridge brass, which is not rolled to thin gauges, and particularly by brass for artillery cartridge cases, on which the mill may finish its work at a thickness between 0.400 and 0.900 in. Obviously, the amount of rolling and the number of anneals to which such a product can be subjected are small compared with strip that is carried to a thickness of a few hundredths of an inch. As a result, critical examination into the internal condition of metal has been made on an extensive scale at a stage of manufacture that would not, in normal times, have been chosen for complete inspection. Under these conditions, a type of defect has been recognized that is not seen at thinner gauges. It might be more accurate to call it the appearance of a defect, since it refers to an apparently laminated, discontinuous structure, which, in fact, does not exist as such, and disappears after suitable treatment. For this reason it has been called a phantom lamination, which the authors consider an appropriate term. It is the purpose of this paper to describe the phenomenon and the conditions of its occurrence and, at least tentatively, to discuss its nature and cause. Great numbers of phantoms may be found in 2:r brass, either hot-rolled or cold-rolled. They are also found in 70-30 brass, sometimes when hot-rolled and generally when cold-rolled. It is not believed that phantoms are confined to these alloys but this paper is limited to them for the purpose of description. Hot-rolled 2:1 Brass For illustration, therefore, a typical cake of hot-rolled 2:I brass has been chosen. This was rolled to a slab 36 in. thick, from a casting 5 in. thick by 24 in. wide by 18 in. high, which was believed to have been sound. After hot-rolling and cooling, the slab was sheared and a portion of such a shear cut is shown in Fig. I. It would be difficult to convince anyone viewing this specimen that the metal was not unsound. The impression would be confirmed by the appearance of a tensile break, as shown in Fig. 2. This is an ordinary tensile-test piece from metal just described. Although there was nothing in its tensile strength or elongation that suggested unsoundness, it appeared run through with pipes and laminations. To question the reality of such a condition would imply questioning the obvious. But, considering the history of the metal, it would be difficult to believe that it could be so bad as it appeared. It seemed reasonable, though, that if the defects were what they appeared to be, they could be traced back from the sheared or broken face.

Jan 1, 1945

By Fred T. Greene

(San Francisco Meeting, September, 1915) MOST of. the recent discussion of the mineral land law published in the Transactions is in the abstract-an exception being Mr. Goodale's paper, The Apex Law in the Drumlummon Controversy,1 which illustrates in concrete instances many of the practical disadvantages of what Dr. Raymond has. called "The Law of the Apex." The present paper, it is hoped, may serve a similar purpose, emphasizing the necessity for a change in our mining laws, and bringing home to mining engineers some of the defects and dangers of our present code. There are many storm centers of "apex litigation" in the Rocky Mountains; and not the least of them is the Wardner camp, where such litigation has been almost continuous since 1892, and the end is not yet. In their decisions, the courts have accepted the claims of the litigants that the " Wardner vein" is a broad zone varying from 250 to 500 ft. in width at the surface. This is the simplest theory which could have been advanced, and probably decreased, rather than augmented, the number of contests; in fact, every one of the claim owners seemed to feel that the greatest advantage would accrue to him if this theory were adhered to. The dominant structural feature of the Wardner vein is a persistent fault, striking N. 40° W., clipping about 40° to the southwest and called the "Wardner foot wall." Fig. 1 is a composite of two adjacent cross-sections of the vein and is a fair representation of the relative size and shape of the orebodies and their relation to the "Wardner foot wall." The country rock is a comparatively thin-bedded sericitic quartzite which has an average strike of N. 80° W. and clips at high angles to the north and south.

Jan 5, 1915

By James B. Cathcart

The potash mine of the International Minerals and Chemical Corp. is about 18 miles east of Carlsbad, New Mexico, in sec 1 and 12, T 22 S, R 29 E, N.M.P.M. Potash is produced from two zones in the Salado formation of late Permian age. The lower zone, consisting of a mixture of sylvite (KCI) and halite (NaCl), lies at a depth of about 900 ft, and the upper zone, in which the principal potassium mineral is langbeinite (K2SO4 2MgSO4), lies at a depth of about 800 ft. Because of the plastic nature of the material, fractures in the Salado formation are extremely rare and have been noted only on the 800 ft level of the International mine. The open fracture described below is almost unique. Only one other open fracture has been noted, and it was on a working face in the same general area as the one described, but was destroyed before the writer had a chance to examine it. According to J. E. Tong, foreman on the 800 level, this fracture was similar to, but smaller than, the one herein described. The saline strata are nearly flat-lying and comprise interbedded layers of halite, anhydrite (CaSO4), and poly-halite (2CaSO4.MgS04.K2SO4-2H2O), with halite predominating. The halite layers contain local concentrations of sylvite, carnallite (KC1.MgCl2.6H2O), and langbeinite. The principal marker in the potash mines area is a bed of anhydrite about 8 ft thick, and 70 ft below the 800 level. This bed contains varying amounts of polyhalite, and locally a few blebs of sylvite. Two principal marker beds are present over most of the 800 level. The lower is the "Middle Salt Marker," a bed of bright-orange halite, which ranges in thickness from a knife-edge to about 0.6 ft, and is usually bounded above and below by thin seams of green or reddish-brown clay. In langbeinite-rich areas, this marker usually contains abundant blebs of langbeinite. The upper of the two principal markers is a green clay seam, containing abundant halite, which ranges in thickness from 0.1 to about 0.5 ft. It is 2 to slightly more than 5 ft above the Middle Salt Marker. No langbeinite of minable grade is found above this clay, and it

Jan 1, 1950

By E. H. Edwards, J. Washburn, E. R. Parker

The mechanism of strain hardening was discussed in connection with some recent observations on the stress-induced motion of dislocation boundaries and on the simple shear deformation of zinc, cadmium, and copper crystals. THE nature of work hardening accompanying plastic deformation of metals has long been the subject of speculation. As early as 1925, Becker' suggested a thermodynamic process to explain slip based on the statistical probability for the occurrence of local glide steps. The theory that plastic glide was due to the presence of lattice defects known as dislocations was first introduced in 1934 by Taylor: and Orowan, and Polanyi.4 Taylor presented a rather complete analysis of the behavior and interaction of dislocations. He assumed a certain type of stress field to be associated with a single dislocation, and postulated that work hardening would result from plastic flow in two ways. First, dislocations following one another across a slip plane might encounter a barrier which would impede their movement, thereby gradually diminishing and eventually stopping plastic flow on that plane. The second mechanism involved the concept of dislocations traveling in opposite directions on nearby planes attracting one another to form a meta-stable lattice. The interaction of dislocations in such an array was shown to be large enough to require an increase in stress before plastic flow would continue. Kochendorfer5,6 extended the concept of work hardening involving a back stress due to an accumulation of like dislocations on a slip plane. He suggested that the formation of a new dislocation is hindered by those dislocations already present. The hardening resulting from the interaction of newly forming dislocations with bound dislocations was designated as "formative hardening," and indicated to be the only type of hardening necessarily connected with the slip process. In another detailed picture of work hardening, Mott and Nabarro7 assumed that sufficient dislocations are primarily present in the crystal as a consequence of growth irregularities (mosaic structure) to initiate slip. Work hardening resulted from the interaction of migrating dislocations with localized internal stresses produced during deformation. More recently, however, Mott8 as modified his treatment to include the generation of dislocations at Frank-Read sources and he accounts for the hardening by the formation of sessile dislocations. It has been widely accepted that metals of hexagonal structure, usually possessing only one set of glide planes, exhibit mechanical behavior markedly different from those having cubic structures. However, the differences in behavior of the two classes may be less fundamental than suggested. Rohm and Kochendorfer9 have shown that a single crystal of aluminum subjected to approximately simple shear gives the type of stress-strain curve associated with the hexagonal metals. Similar behavior has been demonstrated for gold and silver crystals by Andrade and Henderson.'" Thus when glide in cubic metals is restricted to one plane, the strain hardening characteristics closely resemble those of the hexagonal metals. It would appear, therefore, that an investigation of some of the strain hardening properties of single crystals sheared in simple glide might provide a more complete understanding of the phenomenon of work hardening. This report relates a number of recent observations made on single crystals of copper, zinc, and cadmium tested in simple shear. In addition, pertinent observations of effects accompanying stress-induced movement of dislocation boundaries are reported. Experimental Procedure and Results Details of the production and advantages of the type of single-crystal shear specimen employed for the following tests have been presented in a previous publication.n The method of testing makes

Jan 1, 1954

By E. B. Jensen, C. E. Doane, J. F. Pirozzoli

Results of an extensive one-year test of a nonelectric explosives detonating system led to the mine-wide adoption of this system in early 1978. Since that time, further experience with nonelectric initiation has verified the earlier results, which include the following benefits: Electrical insensitivity Improved productivity Cost effectiveness High reliability While electric blasting caps still experience a limited we restricted to trunkline initiation, all heading rounds as well as the bell, undercut, boundary-cutoff, and raise blasting are detonated nonelectrically. The primary blasting agent used at the Henderson mine is AN/FO, and primers are typically one of the following products, depending on applications: PETN, semi-gelatin dynamite, or a nonnitroglycerin water-gel slurry

Jan 1, 1984