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By K. E. Beu

THE integrated intensity X-ray method of meas-uring retained austenite concentrations in hardened plain carbon or low alloy steels as proposed by Averbach and Cohen1,2 has the advantages of being a highly sensitive and precise quantitative method. The various phases of this method have been studied and several modifications have been developed which aid not only in reducing the time required per determination, but which also increase the possible accuracy of the method. A fundamental step in the original calculation procedure is to plot V.A(?) curves for austenite and martensite and to obtain VM/VA ratios from these curves.' In taking this ratio the absorption factor A (8) drops out since it is constant for a. given diffraction angle 8. The reason for eliminating A(?) in this manner is because it is apparently assumed

Jan 1, 1953

By R. W. Bond

The gas-lift is a comparatively recent development in the Oklahoma and Kansas fields. It was used to some extent in the old Dilworth field several years ago, but the first extensive installations were made in the Tonkawa and Garber fields in Oklahoma early in the year 1926. Compressor Equipment During the early development of the system, the equipment used generally consisted of small tandem compressors of about 250 cu. ft. per min. displacement, driven by automotive-type gas engines, using a short belt drive. These compressors were first installed at the individual wells largely as an experiment. After the experimental installations had proved the method a success, it was considered economically advisable to centralize the compressor equipment in strategically located stations. However, as the information in regard to "gas-lift flowing life" was anything but definite, and the most optimistic estimates in regard to it did not exceed six months, portability of equipment was still the first consideration in the minds of many operators, who continued to install srnall semi-portable com-pressors in their centralized stations. As electric power became available in the fields, the electric motor came rapidly into use as the prime mover for the small compressors. The operating cost of this motor is greater than that of the automotive-type gas engine for the same power output, but the greater continuity of service tends to balance the extra cost. Aside from the semi-portable units, a number of strictly portable compressors were used. These consisted of automotive-type gas engines direct connected to vertical compressors. The unit was assembled on one base and could be mounted on wheels or skids as desired. The chief objection to these, in the writer's opinion, was their small capacity— approximately 150 cu, ft. per min.—which made it necessary to use two, three, and sometimes more units per well, thus making the installation rather costly. However, they have been found valuable for test purposes and emergencies, where installation time is an important factor.

Jan 1, 1928

By R. E. Zinkham

An investigation has been conducted to compare short transverse and longitudinal fatigue and fracture properties in 4.25-in.-thick, high strength aluminum alloy plates. One plate was produced using standard rolling techniques while the other was pre.forged before rolling. Little difference was shown in fatigue strength of longitudinal specimens taken from mid-thickness of the plate. Howeuer, in the short transverse orientation fatigue strengths at 107 cycles were about 25 and 50 pct less, respectively, for the preforged and standard rolled plate. Differences in fatigue strengths were attributed to grain size and shape as well US orientation of constituents. Fatigue crack propagation rates and fracture toughness were compared at three different stress intensity (K) levels, using a constant compliance, double cantilever, wedge-shaped specimen. In a given plate, comparable fatigue crack Propagation rates were observed in the longitudinal (i9W) and short transverse (TW) orientations. Somezuhat gveater rates were observed in the short transzerse (TR) orientation. The preforged plute gave a lower rate for all three directions. Considerable secondary cracking developed, at times, over portions of the fatigue crack in both plates, particularly at the lower stress intensity levels in the short transverse specimens. Micro structure revealed constituent stringers as possible causes of the crack branching. Fracture toughness was considerably less in both plates in the short transuerse orientation. It is concluded that preforging not only improved directional tensile properties but also the fatigue and fracture properties in general. On occasion, aluminum plates have been milled away for hinges or bolted connections and stressed through the thickness or short transverse direction. Little or no information is available concerning fatigue characteristics or fracture toughness in this loading orientation in aluminum plate, or of the effect of fabrication on these properties. It was the intent of this project to examine, develop, and apply a unique specimen that has been advocated by others to study the fatigue characteristics and fracture toughness of two differently fabricated high strength aluminum plates. Linear elastic fracture mechanics criteria may be applied to the specimen so that the fatigue crack propagation rate and fracture toughness data may be of use for design or inspection applications. Fatigue characteristics are generally measured in the longtudinal or long transverse direction, where fairly large specimens such as center notched panels,' are usually employed. Limitations are evident due to plate thickness, however, in the type and size of specimen that may be tested in the short transverse direction without extensions. Therefore, a specimen that is to be loaded in this direction should, for convenience, be compact. The general type of fatigue crack propagation specimens discussed and employed herein meet this requirement. These specimens are commonly called double cantilever beam specimens and lately "crackline-loaded edge-crack specimens".2 They may vary from a slope of zero (parallel-sides) to a wedge shape, the type employed herein. In general for most specimens the stress intensity KI at the tip of a crack is a function of the load, P and crack length, a. Some varieties of the wedge shaped specimen, however, give essentially a constant stress intensity KI over a considerable range of crack length.' This feature can be a valuable asset in fatigue crack propagation experiments because the stress-intensity can be controlled simply by controlling the load without regard to crack length. MATERIAL AND METHODS Material. A standard rolled (light pass reduction) and a ~reforged and rolled (heavy pass reduction) plate of 7179-T651 material were used for the evaluation. The chemistry, processing history and average tensile properties are shown in Table I. Specimen Selection and Preparation. The specimen selected for the generation of fatigue initiation or S-N data was an axial tension type and is shown in Fig. 1. Specimens were taken from mid-thickness in the longitudinal and short transverse directions from both plates. Specimens were polished with 500 grit paper in a direction parallel to the loading axis. For the fatigue crack propagation tests, the specimen shown in Fig. 2 was used. This is similar to a specimen that has been employed by Mostovoy3 for fracture toughness studies on 7075-T6 aluminum alloy. It also fortuitiously agrees quite well with the dimensions of a specimen for which Srawley and Gross2

Jan 1, 1970

By David Sinclair, Philip B. Bucky

THE dimensions and shapes of mine structures may at present be determined by (1) field experience, (2) structural calculations, and (3) barodynamic tests.§ None of these, however, provide information as to the stresses, their direction and distribution in a mine structure. For the design of pillars, the placing of openings relative to working places such as gangways, haulage levels, etc., this information is desirable. Photoelastic methods provide this and, while relatively new, their application in all engineering fields is assuming increasing importance. This paper, therefore, will present the method with a few applications to mining, and with sufficient reference for further study by the reader. PART I THE PHOTOELASTIC METHOD The photoelastic method of stress measurement determines the stress distribution in a two-dimensional model by optical means. It makes use of the fact that when a piece of isotropic transparent material, such as glass, celluloid, or Bakelite, is stressed and viewed in polarized** light a picture is seen which indicates by its color bands of light, or fringes, the magnitude of the stresses, their direction and their distribution. GENERAL EXPLANATION The stress at any point 0 in a structure (Fig. 1), may be resolved into two components, P and Q, each a pure tension or compression, at right angles to each other, called principal stresses.1 To fully identify the stress, the values of P and Q and their directions or angle [0] must be known.

Jan 1, 1940

By W. H. Bassett, J. C. Bradley

In considering the effects of reducing gases on hot solid copper the following conclusions have been reached. (I) Depth of deoxidation of copper heated in reducing gas is grealer the smaller the amount of cuprous oxide originally present in the copper, the range studied being from 0.015 to 0.136 per cent. oxygen. It is suggested that the reason for this diflerence in depth of deoxidation is thai, when the copper is low in cuprous oxide, the reducing gas is diluted less by the gas that is formed in the reaction than when the copper is high in cuprous oxide; and the greater the concentration of the reducing gas the deeper the deoxidation. (2) The rate of deoxidation is much more rapid at the beginning of exposure than at the end, a condition especially noticeable at temperatures around 900" C.; that is, deoxidaion is retarded as the depth penetrated by the reducing gas increases. (3) Within the accuracy of the experiments arsenic in copper up to 0.5 per cent. has no tendency to increase or decrease the action of a reducing gas on the cuprous oxide presenx in the copper. In 1912 pieces of 0.365-in. hard copper rod 1/2 in. long were heated in a porcelain tube in an electric furnace, while illuminating gas was passed through. An approximate analysis of this gas is: Hydrogen 38 per cent., carbon monoxide 30 per cent., illuminants 13 per cent., methane 10 per cent., ethane 3 per cent., carbon dioxide 3 per cent., nitrogen 2 per cent., oxygen 0.4 per cent. After heating for various lengths of time at various temperatures, samples were quenched

Jan 1, 1926

By F. D. Rosi

IT was recently shown1 that slip bands can be observed in bent germanium crystals after deformation, by means of etch pits along the slip traces. It is the purpose of this note to show how chemical etch pits can also be usedto examine the appear- ance of slip bands in silicon, as well as other deformation markings. A 30 ohm-cm, p-type single crystal bar, 2x1/4x1/8 in., was plastically bent at approximately 1200°C in a vacuum of 1x10-5 mm Hg. The axis of the crystal was coincident with a <III> direction, and the surface normal to the axis of bending was within 4" of a (110) plane. Prior to the deformation, the (110) surface was mechanically polished with

Jan 1, 1958

By A. H. Daane, A. S. Wilson

The U-Cr system is of the simple eutectic type with some solid solubility of chromium in r and ß uranium. The eutectic occurs at 20 atomic pet Cr and melts at 859°C. The maximum solubility of chromium in y uranium is 4 atomic pet at the eutectic temperature, and in ß uranium the solubility is estimated to be 1 atomic pet. y-ß and ß-a transformations were found to occur at 737°estimatedt° and 612°C respectively. DURING 1944 and 1945, the U-Cr constitution diagram was studied in this laboratory as a part of a research program on uranium metallurgy in the Manhattan Project, and the work was described in a Manhattan Project report issued in December 1945. This paper is based on that report, which has been declassified. Prior to this study, it had been shown by other Manhattan Project workers that the low Cr-U alloys could be quenched to retain the form of uranium. Experimental The uranium used in this work was massive metal prepared in this laboratory and contained less than 0.1 pct of other elements. The chromium was 200 mesh powder obtained from the A. D. McKay Co. and was found on analysis to be 99.5 pct Cr with 0.3 pct Fe the major impurity. Alloys, weighing 400 to 600 g, were prepared by induction heating the components to 1700°C in slip-cast ZrO, crucibles in a vacuum of 3x103 mm Hg. TO prevent too violent agitation of the melt by the induction field with subsequent crucible breakage and sample loss, the ZrO2 crucible was placed in a graphite crucible, which was surrounded by a layer of powdered carbon insulation 2 to 3 cm thick. Polished vertical sections of the alloys were examined microscopically to confirm their homogeneity. Heating and cooling curves were taken on the alloys by reheating them in ZrO, crucibles to 1200°C and inserting a mullite-protected chromel-alumel thermocouple into the melt by means of a slip seal in the vacuum head of the furnace. A recording potentiometer traced the curves which had a slope of from 3" to 6" per min. Samples of the alloys were prepared for metallo-graphic examination by conventional mechanical polishing techniques followed by an electrolytic polish in an ethylene glycol-phosphoric acid-ethyl alcohol bath. The structure of the alloys was brought out clearly by this procedure so that no further etching was required. Samples for chemical analysis were taken from drillings from the top, center, and bottom sections of the alloys. The uranium was determined by titra-tion with Ce(SO1)2, while the chromium was titrated with FeSO,; the uranium and chromium totaled at least 99.6 pct in all of the alloys prepared. X-ray samples were prepared by filing bulk specimens in a helium-filled glove box and annealing the resulting powder in a zirconium-gettered helium atmosphere. A 114.6 mm diam Debye-Scherrer camera and a Weyland nonsymmetrical self-focusing camera were used with filtered copper radiation to obtain the powder X-ray diffraction data. Results The data obtained in this study have been combined to construct the constitution diagram of the U-Cr system shown in Fig. 1 where the arrests observed in cooling curves are indicated by dots. The liquidus arrest was quite distinct in thermal data taken on alloys in the range 0 to 20 atomic pct Cr. The eutectic arrest was not observed in studies on the 2.5 and 4.5 pct Cr samples but appeared in the 7.5 pct samples, which suggested some solubility of chromium in y uranium. On quenching from 859 °C, the 2.5 pct sample showed but one phase while the 4.5 pct sample contained a small amount of the eutectic along the grain boundaries; see Figs. 2 and 3. From this the maximum solubility of chromium in r uranium has been set at 4 pct. X-ray studies on these samples showed that the r phase was not retained at room temperature by quenching, but in each case a pattern was observed .which has been identified with the ß phase of uranium. Thermal data show the y-ß transformation of uranium lowered to 737°C as a consequence of this solubility. On quenching from the ß range (660°C), precipitation of chromium in the primary uranium is observed in the 2.5 and 4.5 pct Cr samples (see Figs. 4 and 5),

Jan 1, 1956

PRESIDENT L. D. RICKETTS,1 NEW YORK, N. Y. PAST PRESIDENTS BENJAMIN B. THAYER,1 NEW YORK, N. Y. WILLIAM L. SAUNDERS,2 NEW YORK, N. Y. FIRST VICE-PRESIDENT SIDNEY J. JENNINGS1 NEW YORK, &apos;_N. Y. TREASURER GEORGE C. STONE,1 NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 4, 1916

By H. C. Rickaby

BY August 1944 Canada expects to be shipping 56 percent hematite ore from its new Steep Rock iron mine, via Port Arthur on Lake Superior, to the steelmaking centers in Canada and the United States. This is indeed welcome news to steel men, especially if they operate open hearth furnaces, as the Steep Rock ore is a high-grade lump and will be valuable as charge and feed ore. But better news is the fact that this first big producer of high-grade hematite ore in Canada, since the exhaustion of the Helen mine in the Michipicoten area north of Lake Superior in 1918, has a proved ore body of 16,757,000 long tons and a probable ore body of 14,000,000 long tons, thus giving an over-all total of 30,757,000 long tons and assuring production for a number of years to come.

Jan 1, 1943

PRESIDENT L. D. RICKETTS,1 NEW YORK, N. Y. PAST PRESIDENTS BENJAMIN B. THAYER,1 NEW YORK, N, Y. WILLIAM L. SAUNDERS,2 NEW YORK, N. Y. FIRST VICE-PRESIDENT SIDNEY J. JENNINGS,1 NEW YORK, N. Y. TREASURER GEORGE C. STONE,1 NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W.. RAYMOND NEW YORK, N. Y SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 6, 1916

By W. C. Hagel

Previous inuestigators have repovted unusually low H* and Do values for self-dzf@szon in certazn bcc metals, e.g., chromium nnd y -uvanium. It has been postulated that this is nn experimental crl -tetion for the existpnce of a four -atom ring meclzanzsm, mid there could be. zmpovtant theoretrcal Implicatlons. By utilizing a precise sectioning technique with Cr51 as the tracer, self-dzffi-lsion measurements in large grains of 99.99-pct Cr were extended from 1200° fo 1600"C. A least- squares analysis of the data yields that D 0.280 exp (-73,20U/RT) cm2 sec-&apos;. These AH* and Do unlues are not anomalous; there is little reason to believe that n vacancy mechanism is not opevatiue. Apparent differences at lower temperatures may result from preferential diffusion along short-circuititing paths and/or sample contamination. WITH continued technological effort, chromium and chromium-base alloys should ultimately become useful high-temperature structural materials. Accurate measurements of self-diffusion coefficients in the pure metal are necessary for a quantitative understanding of sintering, grain growth, creep, and other related rate processes. However, two conflicting determinations have been reported.* Using an Since careful diffusion studies normally yield Do values ranging from 0.1 to 10 cm2 sec-l, the Paxton-Gondolf results require independent experimental corroboration before an undue amount of speculation arises to explain the apparent anomaly. As discussed by Nowick6 and clearly shown by Hoffman and Turn-bull7 for self-diffusion in silver, a low AH* and Do can arise from preferential diffusion along grain boundaries or other short-circuiting paths. The most reliable data come from high-temperature measurements where volume effects predominate. Following a precise sectioning technique developed for determining silver diffusion in the intermetallic compound AgMg8 and cation diffusion in the corundum oxide Cr2O3,9 the purpose of this study was to measure true volume diffusion in high-purity, large-grain samples at higher temperatures than considered previously. Another point of interest is the frequent proposal10-12 that chromium undergoes an allotropic transformation between 1375" and 1800°C where the diffusion data might then show a discontinuity. I EXPERIMENTAL 1) Sample Preparation. The highest purity (99.997 pet) Cr currently available is produced by reduction of chromium tri-iodide. Three pounds of the resulting crystal bar were shipped in a sealed container with a complete chemical analysis from the vendor.* In conformity with the procedure used for

Jan 1, 1962

By John J. Sense

The Mission unit of the American Smelting and Refining Co., located 20 miles south of Tucson, Ariz., is a high-volume, 15,000 tpd operation which utilizes a relatively light equipment fleet. As such, management is very conscious of the mechanical and operational availability of the equipment in use. One of the key items in attaining this efficiency is a complete and reliable record of mechanical and operational machine availability which is an invaluable guide for: 1) Estimating future equipment and personnel requirements of an operating property. 2) Planning an expansion program of an operating property. 3) Estimating equipment and personnel requirements of a new property. 4) Selection of replacement equipment. 5) Comparison of separate operating properties.

Jan 3, 1964

By R. L. Sandefur

Professor Kim&apos;s excellent review article1 on ultimate pit planning contains a statement of the apparently widely held but incorrect belief that "kriging provides information on the confidence limits around the estimate which no other extension technique is capable of supplying." If a geostatistical approach is valid, there are several good reasons for using kriging but uniquely provided confidence limits is not among them. If kriging is possible, then confidence limits can be calculated for any other linear estimate. Kriging is the procedure which finds the weighing coefficients which minimize the estimation variance [ ] is the variance of blocks like the one being estimated. wi is the covariance of the estimated block and the i-th sample. oij is the covariance of the i-th sample and the j-th sample. Ai is the weighing coefficient for the i-th sample. N is the number of samples. The formula for estimation variance can also be used to calculate confidence limits on blocks estimated by any linear combination of sample grades including: 1) Polygons a. Hole nearest block centroid is assigned weight 1. All other holes are assigned weight 0. b. Polygonal area weighing. The samples are assigned weights directly proportional to their polygonal areas of influence within the block. The weights sum to 1. 2) Inverse distance weighing. The samples are assigned weights directly proportional to the reciprocal of their distance to some power from the block centriod. The weights sum to 1. Often only holes nearer than a certain distance and/or the nearest hole in each octant is considered. If there is an antisotropy to the ore body, an elliptical transformation often gives more accurate results. The most popular inverse distance weighing function is inverse squared distances (IDS). 3) Simple average. All samples within a certain distance are assigned the same weights which sum to 1. As an example of the applicability of the above formula to any linear estimate an internal verification on copper grade of 665 blast holes on the 1040 bench at Utah&apos;s Island Copper mine is presented. Internal verification is simple and applicable to non-linear estimates as well. Any sample (drill hole, bulk, trench, or chip) is dropped out, the value of the dropped sample estimated and compared with the actual value. If this is done for all samples, a measure of confidence limits is obtained. Internal verification is used in Cominco&apos;s MEPS system4 and in the BLUEPACK system.5 Comparison of block values against estimates697 is not dissimilar to internal verification. Results of the internal verification are presented below:

Jan 1, 1980

Discussion of a paper of S. S. Rummy and W. F. SCHWEDES, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 94, October, 1914, pp. 2613 to 2635. K. A. PAULY, Schenectady, N. Y.-I have seen this installation and I wish all those interested in the question of electricity as a mine pumping agent could see it. It is not only a model for mine installation, but might well serve as a model for any electrically driven pumping plant. I think I am correct in saying that the pumps are the largest electrically operated centrifugal pumps in mine service in America. I talked with Mr. Rumsey in Duluth just before coming here, and he told me that the actual tests of the equipment as installed checked very closely with the shop tests; that the water delivered by the pumps was slightly in excess of the guarantee, something like 3 or 4 per cent., and that no troubles except of a very minor nature had been experienced with the installation from the start. One point which has been brought out by Mr. Rumsey, and by others who have looked into this question, is the marked saving which&apos; can be made by the application of electricity to pumps, especially to the main sump pumps. The pumps are always located a long distance from the boiler plant and the losses in the steam mains are large. While many of the steam pumps are of a very high grade, yet the tests seemed to indicate that the steam consumption is extremely large. The reduction in operating cost of one small installation which I. have in mind pumping against a head of approximately 2,000 ft.-which by the way was a reciprocating pump-reduced the pumping cost to the neighborhood of one-fifth of the previous steam cost. . The high steam cost was probably due to leakage in the engine and the loss in transmission in the mine, the pumps being located almost half a, mile from the boiler plant.

Jan 4, 1915

By Donald B. Evans, Robert D. Pehlke

The solubility of nilrogen in liquid binary alloys of iron with Litanium. zivconium, columbium, vanndiurn, and tantalum was measured for alloy composiLions up to the solalbility limils of lhe alloy nitrides. All five alloying agents were found to decrease markedly the activity coefficient of nitrogen in liquid ivon. The metal/nitvogen mole ralios in the alloy nitrides formed were generally .found to be slighlly greater than 1.0, but in no case greater than 1.5. From the experimental data, the standard free energies of fortmation of titanium and zir-conium nitrides have been calculated for the Lemperaluve range 1550° to 1750 C. The solublily Products for columbium, tantalum, and vanadium nitrides are also reported. A number of research investigations have examined the effect of refractory metals on the solubility of nitrogen in liquid iron. Although data on zirconium are not available, investigators are in agreement that titanium, vanadium, columbium, and tantalum markedly increase the solubility of nitrogen in liquid iron. This fact alone makes desirable the acquisition of thermodynamic data for these elements in liquid iron. Since refractory metals are known to be stable nitride formers, they have been suggested as steel denitrifying agents, and some of their nitrides have recently been considered as containment materials for liquid iron and iron alloys. Most available thermodynamic data for these metals relate to their dilute concentrations, but effective thermodynamic treatment of these applications requires data at concentrations near the solubility limit of the alloy nitride. Although some work has been done at relatively high alloy concentrations in liquid iron (particularly for vanadium 2,3 and titanium 2,4), the results have been somewhat contradictory. Disagreement may be partly attributed to the fact that the compositions of most refractory metal nitrides have been shown to be nonstoichiometric, and to vary 2,5-8 depending on the temperature and nitrogen gas pressure with which the solid nitride phase is in equilibrium. One purpose of this study consequently has been to determine the compositions of the refractory metal nitrides precipitated from a liquid iron solution. EXPERIMENTAL PROCEDURE Rao and Parlee2 and Evans and Pehlke 9 have discussed the technique for measuring the solubility product of an alloy nitride phase in liquid iron by finding the point of departure of the nitrogen solubility from Sieverts&apos; law. The method consists of measuring the solubility of nitrogen in a melt of iron containing a known concentration of a second metal as a function of the nitrogen gas pressure over the melt. In this study the second metal was one of the refractory metals titanium, zirconium, columbium, vanadium, or tantalum. When the nitrogen pressure at which the refractory nitride forms is reached, a deviation of the measured solubility of nitrogen in the melt from Sieverts&apos; law is observed in the form of a "pressure halt." The concentration of nitrogen in the melt associated with this breakpoint in the nitrogen-absorption curve is then used to calculate the nitride solubility. The Sieverts method was used to measure nitrogen solubility as a function of nitrogen pressure and temperature. The experimental equipment for this technique has been previously described in detail. 1,9 Charge materials used were vacuum-melted high-purity iron (Ferrovac-E) and the best commercial grades of the refractory metals obtainable (in all cases at least 99.8+ pct pure). Recrystallized alumina crucibles were used to hold all melts except those containing zirconium, for which zirconia crucibles were necessary. Temperatures were measured by a disappearing-filament type optical pyrometer sighted vertically downward on the melt surface through a 1/4-in.-diameter sight hole in the crucible lid. By means of a technique previously described, 9 in which the refractory-metal nitride was precipitated at one temperature then redis-solved by raising the temperature 50°C and precipitated again at a higher temperature, it was possible to obtain data over a temperature range of up to 200°C on a single melt. It was found that this technique could not be used with melts containing zir-

Jan 1, 1965

Reserves of Lake Superior Manganiferous Iron Ores Appendix-to paper by CARL ZAPFFE, presented at the Cleveland Meeting and issued, as Pamphlet No. 1664-C, with MINING AND METALLURGY, May, 1927. The author has made several test calculations on the basis of manganese units that are and may be involved. These are summarized here, as follows: On the basis of ore produced since 1902, the average annual requirement of manganese units would be 91,000 tons; on the basis of the production of the past 4 or 5 years, the requirement would be 145,000 tons; on the basis of the year 1925 only, the requirement would be 155,000 tons. Applying the percentage of increase for the next 20 years, as determined by the plat shown as Fig. 3, the total requirement for 20 years would be 3,254,000 to 3,572,000 tons, if one used either 145,000 tons or 155,000 tons as a starting point. We have the following interesting facts: (1) The Michigan ores contain only about one-half the manganese that the Cuyuna ore does; (2) the Cuyuna district now produces one-half the ore required; (3) the known tonnage of Cuyuna reserves is greater than the speculative reserve offered for Michigan; (4) at the present rate of production considered by tons, Michigan ores ought to be exhausted in 20 years or less while Cuyuna ores would last up to 44 years. We should now reduce the estimated reserves to a basis of manganese, units. Using the tonnages listed in Combinations 2, 3, 4 and 5, the reserves total 3,118,225 tons, 3,781,995 tons, 5,041,995 tons and 5,560,342 tons, respectively. Therefore, needing at the most 3,572,000 tons, as shown above, either Combination 3, 4 or 5 will not only suffice but will leave an excess-enough for 1 or 2 years for Combination 3, 9 or 10 years for Combination 4, and 12&apos; to 13 years for Combination 5. This means that for Combination 5, without using tonnages obtained from beneficiating or from mixing poor ores, the reserves are ample for about 33 years.

Jan 5, 1927

By J. C. McDonald

A DDITIONAL experimental data are presented in this note on a phenomenon which has been touched on but lightly in the literature. The common magnesium base rolling alloy (AZ31B) contains about 3 pet A1 and 1 pet Zn. When cold rolled, it hardens until it starts to break up in the rolls at 30 to 50 pet reduction. When it is heated after rolling to full hardness, it softens. However, other magnesium alloys have shown themselves capable of being cold rolled indefinitely, provided the ratio of roll diameter to starting gage is sufficiently high. As measured by the tensile test, these alloys actually soften when the reduction becomes large (60 to 90 pct). A subsequent heating at 300&apos; to 500°F can produce hardening of this metal. Heating at higher temperatures (600&apos; to 800°F) causes recrystalliza-tion and softening. Menzen&apos; has shown that a magnesium base alloy can be cold rolled without intermediate anneals as much as 90 pet. The alloy studied, Mg-1.5 pet Mn, softened considerably between 20 and 90 pet reduction, as measured by tensile properties; a decrease in yield strength of 30 pet, and an increase in elongation from 3.2 to 16.7 pet (longitudinal direction of the sheet). However, Menzen gives no data on the reaction of this metal. to heating. Ansel and Betterton2 and Hurst and Hatch3 report a similar effect in Mg-1.5 pet Mn-0.1 pet Ca. Their data show an initial hardening, followed by softening. The former authors also show that the alloy softened by cold rolling will harden when heated at low temperatures, and that these effects are absent in Mg-3 pet Al-1 pet Zn. In the course of work4, 5 some years ago, the author observed similar effects with alloys containing cerium, thorium, or zirconium; but not with elements like aluminum, silver, or zinc. Table IA contains the results of an experiment which shows these effects rather well. A binary alloy with 0.3 pet total rare earths (Mischmetal* added) was rolled hot to 1/16 in. and then annealed to full softness by heating 30 min at 800°F. Rolling was continued at 1.5 pet per pass to 80 pet total reduction on 8 in. diam rolls. The metal was harder after 20 pet work than initially but, at 80 pet reduction, properties were back to their original values. Heating for 1 hr at 450°F produced about the same hardness whether the reduction was 20 or 80 pet. At intermediate reductions, the metal hardened, but not to as high values. Extensive cold rolling may also be carried out on metal hot rolled at temperatures sufficiently low to produce a semihard temper. Mg-0.6 pet Zr was rolled to 0.1 in. at 700° to 800°F, 30 pet per pass. As shown in Table IB, a further cold reduction of 85 pet, at 1.5 pet per pass, definitely softened the metal.

Jan 1, 1959

By L. D. Clark, S. S. Saluja

A physical law, governing the rupture of rock by confined explosive charge correspondent to current expressions for determining weight of charge to rupture rock burden, W, was developed in the form Q = cVw3 by two early investigators performing unique experiments with ice. The coefficient C, is found by trial blast. Recent physical tests conducted with rock, synthetic materials and ice to establish the validity of the theory on which it and other related formulae are based indicated: (a) that failure under hydrodynamic impact pressure is by tension rather than shear as was assumed; (b) that the fundamental law of mechanics, enabling the determination of Q = cvw3, modified to the form P = R x Sa x Wb is valid when low velocity explosives are used; (c) that rock breakage under the action of low velocity explosives is entirely due to explosion gas pressure, as was believed; (d) that under the action of high velocity explosive it is due to the joint effects of scabbing and gas pressure; and that further possible modification could make the above equation also applicable to these joint mechanisms. shape could be easily frozen and because large loads would not be required. They found: (a) that the not unfamiliar shearing equation for metals was applicable to ice where P = load in lb; S = periphery of pressure surface, in.; W = burden, in.; K = modulus of rupture by shear in lb per in.2; and (b) that "the form of cavity produced by the application of gradual pressure is similar to that obtained by blasting in rock under similar conditions of free face and pressure surface!" This similarity in crater shapes leads to the conclusion that rock would rupture by shear, as did ice, and its behavior under the force of a blast could be governed by such a relationship as P = S x W x K. Three important interrelated empirical expressions were derived and rock, charging and spacing coefficients C,, C, and e were established and substantiated by trial blasts. In checking the accuracy of the main assumptions, duplication of the ice tests, substituting rock, suggested that K is not constant and that P = K x W x S, though valid for ice, does not necessarily hold for homogeneous limestone.&apos; Conclusions from this later work raised questions making continued investigation desirable because such conclusions do not destroy the practical value of the empirical equations or theory. Further study for the establishment of the relationship between load, burden and periphery of the pressure surface and possible application of these to the mechanism of rock blasting was undertaken by the authors of this paper. MECHANICAL TESTING - EXPERIMENTAL PROCEDURE Certain inconsistencies in the results of the aforementioned tests repeated on three types of limestone suggested these inconsistencies be attributed to rock inhomogeneity. It was also suspected that the loading speed, which could not be held uniform, may have contributed. The earlier work with both rock and ice

Jan 1, 1964

By William R. Rumbold

When I was in South Africa during the latter part of 1904, there were three known tin-fields, which may be called the Cape Town, the Bushveld, and the Swaziland fields. The Cape Town Tin-Field. This district is situated near Kuils river, 20 miles west of Cape Town, and 5 miles from Kuils River station on the Cape Town & Stellenbosch railway. The deposits are in granite, intrusive in the Malmesbury beds, which are supposed to be of Silurian or Cambrian age. The granite, resisting denudation better than the surrounding shales, has formed low-lying hills, the highest of which, the Bottlelary Berg, is 1,510 ft. above sea-level. The rock consists of quartz, orthoclase feldspar, and biotite mica; tourmaline is also present. The feldspar occurs in large crystals. The rock is generally decomposed on the surface, and the decomposition sometimes extends as deep as 100 ft. This formation—granite intrusive in Silurian shales— extends for many miles to the northeast, but so far as I know the Kuils River deposits are the only ones now known to occur in it, though probably further prospecting will reveal other deposits. This particular discovery was accidental; alluvial tin being found in the course of boring for oil. The Kuils River Deposit. This deposit comprises both lode and alluvial tin. The lode strikes N-S., and dips about 30&apos; E. into the hill. It is 5 ft. wide, and composed of dense white quartz, in which pinkish-gray cassiterite is distributed in large crystals. The vein also contains considerable quantities of wolframite. Fig. 1 is a rough plan of the relative positions of the lode and the alluvial deposit, the latter, as shown, following the course of a stream, while the lode crops out on the hillside ,

Jan 1, 1909

By Donald A. Brobst

The minerals barite (BaSO4 barium sulfate) and witherite (BaCO3 barium carbonate) are the chief commercial sources of the element barium and its compounds whose many uses are nearly hidden among the technical complexities of modern industrial processes and products. Barite, the major ore mineral, is extremely vital to the petroleum industry which in 1973 consumed at least 80% of the world&apos;s produc¬tion of 4.4 million tons as a major ingredient of the heavy fluid, called mud, that is circulated in rotary drilling of oil and gas wells. The re¬maining 20% of the barite production was consumed chiefly in the manufacture of barium chemicals and glass and as a pigment, filler, and extender. Barite occurs throughout much of the world and is available from three major geologic types of deposits-vein and cavity fill¬ing, residual, and bedded-in sufficient quantity at competitive prices to meet current demands. The world&apos;s demand for barite is expected to increase, and geologic circumstances are favor¬able for the discovery of new deposits of com¬mercial value. Witherite is much less common and abun¬dant than barite, although it is more desirable in many ways as a raw material for the pro¬duction of barium chemicals. The United States has not produced witherite since about 1950; England is currently the chief producer of witherite. End Uses Most of the world&apos;s barite production since 1926 has been used as a weighting agent for the muds circulated in rotary drilling of oil and gas wells. The muds fundamentally are mixtures of water, clay, and barite in different proportions that vary according to local reservoir condi¬tions. Muds with a specific gravity as great as 2.5 are used. The mud is pumped down the hollow drill stem, passes through the bit at the bottom of the hole, and rises to the surface in the space between the drill stem and the wall of the hole. In the course of this circulation the drill bit is cooled, cuttings are removed, the drill stem is lubricated, the walls of the hole are sealed, and the hydrostatic head of the column of weighted fluid helps to confine high oil and gas pressures. The latter feature aids in prevention of gushers, thus reducing both environmental pollution and waste of oil and gas resources as well as conserving the natural reservoir pressure for greater production and rate of recovery of the products contained in the rocks. Barite is particularly well suited for drilling mud because it is clean, easy to handle, soft (nonabrasive), heavy, virtually inert chemi¬cally, and relatively inexpensive compared to many other available heavy materials. Barite is used in the manufacture of glass in continuous tanks. The addition of barite ho¬mogenizes the melt and gives greater brilliance and clarity to the finished glass. Ground barite, both unbleached and bleached by sulfuric acid, is a common industrial filler, extender, and weighting agent. The rubber in¬dustry is a major consumer of barite as a filler. Barite also is added to bristolboard, heavy printing paper, playing cards, rope finishes, brake linings, clutch facings, plastics, and li¬noleum, to name but a few uses. Bleached barite has long been an extender in white lead paint because of its weight. The low index of refraction of barite, however, makes its ability to cover marks poorer than some other sub¬stances, but its low capacity for absorption of oil is a good feature. Off-color or unbleached barite can be used as a filler in colored paints. In the construction industry, some lump barite is used in concrete aggregate to weight down pipelines buried in marshy areas and to shield nuclear reactors. Because barite absorbs gamma radiation well, its use reduces the amount of expensive lead shielding otherwise

Jan 1, 1975