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By M. J. Hordon, M. A. Wright

The well-defined increase in fatigue life observed o many metals cyclicly strained at vacuum levels below 10-1 to 10-3 torr has been attributed to the critical retardation of oxygen or water vapor chemisorption at the crack tip during crack propagation.1-3 In the absence of strongly adsorbed surface films, crack re-welding during cyclic compression or dislocation escape from the plastic zone around the crack tip has been proposed to account for the observed decrease in the rate of crack growth. The increase in the critical pressure required for the transition in crack growth rate with temperature experimentally determined for aluminum was found to be generally in accord with the adsorption rate model.4 However, although the adsorption mechanism would also predict an increase in transition pressure and fatigue life with increase in cyclic loading rate, and such effects were noted by Snowden5 for lead and Hordon3 for aluminum, the opposite results were reported by Kramer et al.B in studies on aluminum. The present note describes some recent measurements of the fatigue properties of 1100-H14 aluminum at low pressures to determine the specific effect of cyclic strain frequency in the transition pressure range. Flat cantilever-type specimens of 1100-H14 aluminum shaped to produce a uniform strain gradient along the gage length were tested in reverse plane bending at constant deflection amplitudes in two independent multi-specimen vacuum fatigue systems. One series of tests using 2-in. gage length specimens was conducted in an ion pumped apparatus with 107 torr and 50 cps capacity, denoted as Unit I, utilizing fixed mechanical cams to impose the strain amplitude. An independent test series using shorter 1-in. gage length specimens was conducted in a cryopumped apparatus designed for extremely low pressures below 10-10 torr, denoted as Unit II, using an electromechanical vibrator at non-resonant frequencies up to 150 cps to provide the deflection. Both vacuum fatigue units and associated test procedures have been described previously.3'7

Jan 1, 1969

By L. S. Castleman, R. K. Hotzler

We are currently studying the effects on recrys-tallization of impurities diffused into dispersion-hardened alloys. Our interest in this phenomenon was originally aroused by the observation that the recrystallization temperature range of tungsten "doped" with alumina and silica, or with thoria, is lowered drastically if nickel is plated onto the tungsten prior to heat treatment.' In this note, we report a similar effect that sulfur has on the recrystallization behavior of thoriated nickel. The experimental procedure for this exploratory phase of the investigation has consisted simply in heating commercially obtained stress-relieved samples of thoriated nickel for varying temperatures and times in sealed capsules containing air and small quantities of sulfur. The samples contain 2.4 vol pct thoria and initially less than 18 ppm S by weight; they are prepared either from 0.5-in.-ciiam rod stock or from 0.092-in. sheet and are in the "as-received" (stress-relieved) condition prior to exposure. In an atmosphere free of sulfur, such samples do not show evidence of recrystallization after being annealed for 1 hr at a temperature of 2500°F (1372C).2 The photomicrograph in Fig. 1 shows the microstructure of one of our samples annealed for 75 hr at 1000° C (1832°F) in a sulfur-free capsule. The grain structure is hardly evident (if at all) at 465 times magnification. In contrast, the photomicrograph of Fig. 2 shows the recrystallization that has taken place in a sample exposed to sulfur for 5 hr at 1000°C (1832°F). A nickel sulfide phase is visible at the grain boundaries of the light-appearing grains. We have also observed recrystallization to occur in a sample annealed at 600°C (1112°F) for 25 hr. This temperature is below the 637°C (1178°F) eutectic in the Ni-S system. In the latter case, no nickel sulfide phase is evident in the microstructure. Moreover, we have noticed the occur-

Jan 1, 1969

By H. F. Porter

MUCH has been written relative to the errors involved in the use of a galvanometer for measuring thermocouple electromotive forces. In general, it may be said that accuracy with a galvanometer is secured only at the sacrifice of durability, unless manual adjustment is made in the operation of the instrument to overcome the errors of resistance. and resistance changes. The pyrovolter and the potentiometer both require manual adjustment for every reading, readings being taken on a "null" method. To the end that some of these balances may be eliminated and only an occasional balance be made as a check reading, the "continuously deflecting pyrovolter" was developed. Essentially, the operation of the continuously deflecting pyrovolter is to determine the resistance of the thermocouple circuit, though its value is not noted or indicated, then throwing in series with the thermocouple sufficient resistance to bring the sum up to some standard value for which the indications of the galvanometer will be correct. This result may, however, be accomplished in a somewhat simpler manner, for which general method patents are now in the course of application. If we devise a galvanometer circuit so that by means of a simple adjustment the resistance of the entire circuit will be rendered equal to some constant predetermined value, we may rely on the galvanometer to give correct e.m.f. indications (assuming that the errors of temperature resistance coefficient and cold junction have been properly allowed for), and will indicate temperature continuously where the e.m.f. measured is developed by a thermocouple.

Jan 9, 1919

Noranda Mines, of Quebec, signed a contract for construction of a $20 million copper refinery at Gaspe, P.Q. The plant is expected to have a 65500-ton daily capacity for both concentrator and smelter. Extensive drilling. around Gaspe has revealed more than 65 million tons of 1 to 2 pct copper in several deposits. Cerro de Pasco Corp. has called a special stockholders meeting for August 19 to obtain permission to engage in the oil and natural. gas business, in addition to its present production of zinc, lead, copper, silver and other metals. St. Joseph Lead Co. recently entered the oil development field. The United States, Canada and Great Britain have agreed to establish a permanent organization to work on unification of engineering standards. General accord has been reached on drafting standards and practices, screw threads, fittings for gas cylinders, and fits and tolerances. Permanent committees will study these fields. Reconstruction Finance Corn approved the largest sum in its history. for a mining enterprise when it loaned $94 million to San Manuel Copper. Corp., of Pinal County, Ariz. The loan will be used to increase production of copper and molybdenum, in what was described as-the biggest copper deposits in the country. Three large gold mining concerns operating in the Philippines told the Philippine Wage Board that they would be forced to close if they had to boost miners' wages 500 to $2 per day. The companies are Mindanao Mother Lodes, Benguet Consolidated, and Balatoc Mining Co.

Jan 1, 1952

By F. A. Hill

Coal mining in the State of Washington offers many interesting problems for the mining engineer, due to the varied physical conditions occurring in different fields, and often in the same mine. The different coal seams worked in the same mine commonly require different mining and transportation methods for economical operation. The coal measures have inclinations ranging from 5' to vertical, and in the same mine the dip of the coal may vary from 30' to 50 . In all fields, the seams are extensively faulted, folded, and sheared. The quality of the coal produced ranges from brown lignite to bituminous coking coal, the following being typical analyses: Very little of the coal contains as much as 0.75 per cent. sulfur. The brown lignites occur mostly in Lewis and Thurston Counties, and as a rule are very cheaply mined. This coal has been successfully used in locomotives of the Oregon & Washington Railroad, after equipping them with specially designed fireboxes. The sub-bituminous coals occur in all the coal-mining counties. Their cost of production varies widely, according to the character of the formations, the pitch, and the wall conditions. This makes a fairly good steam coal, but the lump is used mostly for domestic trade, after grading into lump, nut, and pea. The coking coal is used for making coke, and for locomotive and other boiler fuel. It yields a strong metallurgical coke, quite high in ash, though seldom exceeding 18 per cent. ash. Most of it is susceptible to

Jan 1, 1920

By Oscar Lachmund

DURING the driving of the main haulage level at the Copper Mountain mines of the Canada Copper Corpn., Ltd., near Princeton, B. C., some very rapid driving was clone, though no claim for a world's record is made. Conditions, however, were unfavorable for economical operations. The cost of power was high, for the fuel was of poor grade; besides, during the time the work was in progress, very little other power was needed so that most of the power cost was charged against the footage. The FIG. 1.-DRIFT ROUND USED IN MAIN HAULAGE LEVEL, COPPER MOUNTAIN, B. C. transmission line consisted of No. 4 galvanized iron wire with the result that the line loss was considerable. The voltage transmitted was about 30,000. The plant was operated under a lease, which was due to expire about the same time this work was supposed to be completed; an extension was refused, therefore speed was most important. The plans called for a straight adit 2900 ft. (884 m.) in length. At a point 2800 ft. (853 m.) from the portal, two raises were to be put up to the next nearest workings, a difference in elevation of about 800 ft. (243 m.). One of these was to be a two-compartment hoistway and the other a zigzag ore pass, or muck run. A location for these raises had been determined by a number of diamond-drill holes, but the material to be penetrated by the alit was not known. It seemed imperative to get the tunnel work completed as rapidly as possible, in

Jan 3, 1919

By Oscar Lachmund

During the driving of the main haulage level at the Copper Mountain mines of the Canada Copper Corpn., Ltd., near Princeton, B. C., some very rapid driving was done, though no claim for a world's record is made. Conditions, however, were unfavorable for economical operations. The cost of power was high, for the fuel was of poor grade; besides, during the time the work was in progress, very little other power was needed so that most of the power cost was charged against the footage. The transmission line consisted of No. 4 galvanized iron wire with the result that the line lass was considerable. The voltage transmitted was about 30,000. The plant was operated under a lease, which was due to expire about the same time this work was supposed to be completed; an extension was refused, therefore speed was most important. The plans called for a straight adit 2900 ft. (884 m.) in length. At a point 2800 ft. (853 m.) from the portal, two raises were to be put up to the next nearest workings, a difference in elevation of about 800 ft. (243 m.). One of these was to be a two-compartment hoistway and the other a zigzag ore pass, or muck run. A location for these raises had been determined by a number of diamond-drill holes, but the material to be penetrated by the adit was not known. It seemed imperative to get the tunnel work completed as rapidly as possible, in

Jan 1, 1920

ONE of the perplexing problems that face the translator of an old technical treatise is the question of terms for units of weight and measure. We have used an English word only when it is linguistically equivalent to the Italian one and is a unit of approximately the same size. Libbra and oncia thus become pound and ounce, for the actual weights were within 10 per cent of the modem Troy weights. On, the other hand, the length measures braccio, palmo, and dito, which could be rendered literally as arm, palm, and finger or digit, respectively, have no good English metrological equivalents and it has seemed best to retain the Italian words. The exact transfer of Biringuccio's weights and measures into modern terms is impossible because of the uncertainty as to his standards. Even as late as 1803, when the metric system was first introduced into Italy, practically every city had its own standards. There were, for example, at least eight different palmi, varying from 22.3 to 29.2 centimeters. The values listed below for the various units mentioned by Biringuccio are the Florentine ones, which were also used in Siena and Tuscany: [ ]

Jan 1, 1942

It is doubtful if the far-reaching sociological influence and effects of the last few years will be fully appreciated within the present generation, but there are certain lessons and morals already apparent from which we should profit immediately. One of these has been an insistent, though vague, feeling among engineers and men of technical training and experience, that their worth as political and economic factors is not recognized by society. This feeling has found expression first in a tendency on the part of these men to organize for the purpose of securing recognition, or to demand greater activity in their interest on the part of societies already organized. However it may be accomplished, the demand for some means of binding engineers together for purposes of self-interest and public good is in the air and will not be denied. In other words, the time is' propitious for two things: vastly increasing the membership of engineering societies, and serving that membership according to its desires. There are particular reasons why every mining and metallurgical engineer, in the United States at least, should hold membership in the

Jan 6, 1919

By Arthur E. Granger

IN the early days of the science, and until the recent past, geologists worked as individuals or in small groups. Prior to 1930 perhaps the largest single group under one administrative head was the Geologic Branch (now Division) of the U. S. Geological Survey, which employed at that time (including temporary help) 100 to 150 geologists. Today that same unit employs some 1500. In industry some companies employ as many as 100 geologists in a single department. These numbers obviously pose a need for administration. The basic qualifications for good administration are the same for any group of human beings, but the administration of geologists presents some special problems. Choosing Administrative Personnel: There are two kinds of personnel needs: 1) technical, which requires professional geologists who have proved their capabilities in the field, and 2) clerical and fiscal, which provide the necessary supporting or housekeeping functions. This discussion will be concerned only with the first category, except to point out the need for competent and understanding help from clerical and fiscal people and close relationship between top administration, technical or professional personnel, and the clerical and fiscal groups.

Jan 7, 1957

By W. H. Wamsley

Used in combination with conveyor belt haulage, bucket wheel excavators offer unusual possibilities for low excavation and haulage costs. Originating in Germany, these machines are now in use or on order for Australia, Northern Rhodesia, the Belgian Congo, Italy, Yugoslavia, France, Belgium, Indonesia, and the Union of South Africa. A diamond mine in South Africa that has been using German bucket wheel excavators since 1928 purchased American cable-way excavators and American scraping equipment after the war. Operating cost for this equipment was double that for the bucket wheel machines operating in the same mines with crawler-mounted stackers. Machines built and operated in the U. S. are, as far as the writer knows, confined to the northern Illinois coal field, where they are used in conjunction with large shovels to strip overburden too high to be reached by the 30 to 40-yd shovels. Their long stacker belts can deposit the spoil far enough behind the coal face to avoid slides, in such a manner as to make reclaiming the land easier. These large, specialized machines are now being made by Bucyrus-Erie Co. but are not adaptable to many open pit mining situations.

Dec 1, 1956

By A. M. Gaudin, W. D. Charles

IN flotation lime is used to depress pyrite. For this purpose it is preferred to caustic soda. The low cost of lime and the widespread availability largely account for this preference. However, there is some evidence' that pyrite is more readily depressed by calcium than by sodium ions at the same pH. To measure the difference in adsorption of calcium and sodium, which is thought to lie at the basis of the differences in depressing action, radionuclides of calcium and sodium have been used. The experimental work has included an evaluation of the effect of dissolved oxygen, of the concentration of calcium or sodium, of the concentration of hydrogen ion, and of the anions present. Preliminary work in the investigation entailed preparation of the pyrite, development of a technique for counting pyrite coated with Ca and Na, the radionuclides used, and development of an apparatus to study the adsorption of calcium and sodium on pyrite. The main experimental work included calcium adsorption and sodium adsorption studies detailed below. The following are the most salient observations made during these experiments. Oxygen in solution increases the adsorptive power of pyrite for calcium

Jan 1, 1954

POSITIONS VACANT No. 255. A company manufacturing malleable iron fittings in Connecticut needs a manager for its steel department. Experience with converter is essential. No. 256. A prominent mining company in Central America wishes a shift boss for its mill and cyanide plant, who is technically trained, experienced, and can speak Spanish. He should he sufficiently expert to be able to take entire charge of the mill in case of emergency. Salary $150 per month on a two years' contract, with additional allowance for board, lodging and transportation expenses. No. 257. A Mexican copper mining company in the State of Puebla needs an engineer on surveying and mapping and drafting in connection with field construction. Healthy locality. Salary $150 per month.

Jan 1, 1918

By A. F. Crawley

THIS communication reports measurements of the densities of dilute liquid alloys of 0.1 and 0.5 pct Ag in Sn over temperature ranges of 170" and 210°C, respectively, above the melting point of pure tin (232°C). The work was earried out to provide accurate density data for some liquid diffusion studies performed by Davis.1 Densities were measured using a pycnometric technique established in this laboratory. Earlier papers2, 4 attest to the accuracy of ±0.05 pct and the reliability of the method. Tin, 99.999 pct pure, and silver 99.99 pct pure, were melted in a graphite crucible in a vacuum furnace and held at temperature for 10 hr to ensure homogenization. Ingots suitable for machining

Jan 1, 1970

By A. F. Peterson

MUCH has been said and written about the engineer shortage. The mining branch in engineering has lagged during the past several decades. I can think of two institutions, formerly prominent in that field, that have discontinued this department and another that has branched from a purely mining school into various forms of engineering. Conversely, I do not recall any institutions that have added mining to their curricula. I believe that this action is in direct response to the demands of incoming students. But I also believe that while there is a specific demand for civil, mechanical, and electrical engineers in the highly complicated mining operations of today, our need for mining engineers capable of assuming top responsibility for mining operations is unchanged.

Jan 3, 1957

By M. S. Klima, P. T. Luckie

An evaluation of the operating performance of a recently designed pneumatic centrifugal classifier is presented. This classifier has been modified from a separate air and feed input design to an entrained solids in air feed input. The evaluation first required determining the size distributions for the three streams (feed, fine, and coarse). Using size distribution data and mass flow rates, a size selectivity curve was calculated for each operating condition tested. This curve, in turn, was characterized by appropriate selectivity parameters (i.e., the equiprobable or cut size, the sharpness index, and the apparent bypass values). The variation of these parameters with classifier operating conditions was examined. From these evaluations, the "best" operating conditions for the classifier were then determined.

Jan 1, 1985

By K. E. Barrett

Exxon owns a uranium mill and holds two mining leases in Live Oak County, Texas, about halfway between San Antonio and Corpus Christi. The properties make up the Felder Uranium Operations which was reopened earlier this year. Exxon held an oil, gas, and other minerals lease on the J. C. Felder tract, which was adjacent to a relatively shallow uranium discovery by Susquehanna-Western, Inc. on the Marrs-McLean lease immediately south of the Felder property. Drilling in 1967 and 1968 confirmed the presence of reduced uranium mineralization in the basal sand unit of the Oakville formation on the Felder tract, which formed the major part of the roll-front deposit. In 1969 Exxon and Susquehanna-Western, Inc. entered into a sale and purchase agreement which provided for Susquehanna to mine and process Felder ore and purchase recovered uranium. Susquehanna moved an alkaline-leach mill from Wyoming, erected it on the Ray Point property, and placed it into operation late in 1970. Susquehanna mined and processed ore from the Felder and McLean properties through March 1973. Susquehanna ceased operations in March 1973. Exxon then acquired the mill and mill property. Exxon also purchased the mineral rights to the McLean lease, re-negotiated a mining lease for that property, and carried out shut-down programs for the mining and mill areas in the fall of 1973. The project was put on a standby basis until late 1973, when Exxon initiated mine feasibility studies for the project. MINE PLANNING EVALUATION The feasibility study for reopening the Felder Project began in late 1975 and was not completed until late 1976. I will discuss several areas of the feasibility study that required additional work prior to making the decision to renew operations. Ore Reserves Preparations for estimating the ore reserves began with the re-evaluation of more than 1500 natural radioactivity logs from exploration and pre-development drilling that had been completed on the property. These gamma ray logs of non-core rotary drill holes were the principal source of data used in making the estimate. Chemical assays of cores from the deposit were also used in the reserve determination. Electric resistivity and self-potential logs were made along with the gamma ray log. In December 1975 an additional core drilling project was undertaken to confirm the in-place density and radiometric equilibrium characteristics of the ore deposits. Comparison of chemical assays of cores with the U308 values calculated from the logs showed that the unoxidized ores were in radiometric equilibrium. In contrast, cores from anomalies occurring in near surface, weathered, and oxidized zones were in radiometric disequilibrium. Several important decisions were made in developing a mine plan or schedule of production from the Felder and McLean ore bodies. Disposal of Produced Mine Water: The ore bodies of the Felder Uranium Project occur at a point below the ground water table. The ore zones to be mined must first be dewatered to allow removal of mineralized material. In the open pit operations, this is accomplished by maintaining a perimeter ditch around the periphery of the open pit, allowing the interior of the pit to drain and collect into a sump and be pumped from the mine. In addition to anticipated water production from future mining operations, approximately 200M gallons of water was contained in three open pits left from prior mining operations. In two of these existing pits, the water was to be removed and disposed to allow for planned backfilling of waste material into these pits. The third pit would also have to be drained to allow continued mining of an area left from the prior operations. Essentially no ground water information was available for this area. The only data available was water production history from Susquehanna's mining operation. Two water wells were drilled early in 1976 on the Felder lease for use in obtaining hydrological data. A long term draw-down test was performed by pumping one water well and measuring water level drawdown in both the pumped well and the observation well. From these data, values for permeability and storage coefficient were calculated. These data were then used in modeling the aquifer to allow calculation of water influx into the mining area versus time. Once a schedule of water production, including the stored volume in the existing pits was calculated, alternate solutions for disposal were evaluated. The first system evaluated was a series of deep injection wells. The wells were designed to inject at a depth of approximately 3500 feet. Again very little information concerning reservoir characteristics of the receiving sand units was known. Using assumed values for reservoir permeability and storage coefficients, an injection well system was designed to allow for disposal of produced mine water. The biggest

Jan 1, 1979

By E. S. Machlin

The wzodel of Blandin and Diplunt;, generalized to include a phase factor, is applied to the carbon-carbon interaction in iron. Darken&apos;s "energetic" model is generalized to include not only first neighbor interactions but further neighbor interactions as well. On the bases of these generalized models relations are derived for the activity of carbon in both austenite and ferrite in terms of the carbon-carbon Pair interaction energies. A single function then yields the pair interaction energies consistent with the experimental activities of carbon in both ferrite and austenite. Thus, a simple explanation is given for the observation that the nearest-neighbor interaction between carbon is repulsive in austenite and attractive in ferrite. Certain consequences of this approach are explored. OnE object of the present paper is to attempt to take into account the consequences of electrostatic contributions to the carbon-carbon pair interaction energy for carbon as a solute in iron. Friedel&apos; has shown that oscillations in electrostatic potential are to be expected about a solute atom in a metallic solution. Blandin and 6lant6&apos; have shown that such oscillations yield an interaction energy between pairs of solute atoms that obeys the relation: W{ = A cos(2ftFri + 4>)/(kFri)3 [l] where kF = Fermi wave vector, ri = distance between solute atoms comprising the pair7 <p = phase factor dependent only on electronic nature of solute and solvent, A = coefficient dependent only on electronic nature of solute and solvent. Machlin3 found that Eq. [I] accurately described the pair interaction energy derived from short-range order measurements based on field ion microscope observations of dilute alloys of platinum. He also found that the value of the phase factor $ derived from residual resistivity measurements agreed well with that obtained from the analysis of the short-range order data. Harrison and paskin4 were able to predict the long-range ordering energy of 0 brass using Relation [I] and residual resistivity values to predict the value of the phase factor $. Machlin5 has repeated their analysis and applied it to the prediction of the long-range ordering energy in AgZn and AgCd with excellent agreement between prediction and experiment. Both A and $ are independent of the crystal structure. The Fermi wave vector depends uniquely upon the conduction electron concentration per unit volume in the spherical approximation of the Fermi surface. Thus, Eq. [I] is expected to apply to both fer- rite and austenite with only one set of values of A and $. Mossbauer studies6 yield the result that iron has one 4s electron. We shall make an assumption found to hold previously for platinum3&apos;7 and nikel, which is that only the s electrons are involved in shielding the perturbing potential of carbon. With this assumption, kF = 1.35 A-l. Although A and $ may be obtained from certain mdels&apos;&apos;&apos; we shall take A and $ to be empirical constants in the spirit of Kohn and osko.&apos; Thus, Eq. [I] involves two adjustible parameters. Consequently, two independent relations in A and $I are required in order to evaluate them for carbon as a solute in iron. We may use a recent analysis of Aaronson, Domain, and poundg who showed that Darken&apos;s energetic model,1° as well as others, can be used to describe the activity-temperature data for carbon in iron in both the aus-tenitic and ferritic phases. Darken&apos;s model takes into account only first neighbor pair interactions. For our needs, all neighbor pairs need to be taken into account. It is convenient to generalize Darken&apos;s model. The result for the partition function for austenite is: over the temperature range 800" to 1200°C and where the uncertainty corresponds to one standard deviation. Eq. [4] effectively yields only one relation. Another relation is required to obtain unique values for A and $. One property of Eq. [4] is that it is independent of crystal structure. Hence, data for a iron can be used to obtain another relation. To arrive at this relation we must generalize Eqs. [2] and [3] so that they may be applied to the bcc a iron. The result is that:

Jan 1, 1969

By E. N. Smith, J. C. Redmond

The increasing need for materials capable of withstanding higher operating temperatures for various applications such as gas turbine blading and other parts, rocket nozzles, and many industrial applications, has brought consideration of cemented carbide compositions. The well known usefulness of cemented carbides as tool materials is attributable to their ability to retain their strength and hardness at much higher temperatures than even complex alloys. However, it has been found that the temperatures encountered in cutting operations do not approach by several hundred degrees1 those involved in the applications mentioned above where the interest is in materials possessing strength and resistance to oxidation at temperatures of 1800°F and above. At these latter temperatures, the tool type compositions which are made up essentially of tungsten carbide are found to oxidize very rapidly and to produce oxidation products of a character which offer no protection to the remaining body. As a further consideration, the density of the tungsten carbide type compositions is high, from about 8.0 to 15.0. The refractory metal carbides as a class are the highest melting materials known as shown by Table 1 which summarizes the available data from the literature for the carbides of the elements which are sufficiently available for consideration for these uses. The density is also included in the table, since as mentioned above it is an important consideration in many of the applications for which the materials would be considered. It has been established that in the tool compositions the mechanism of sintering with cobalt is such as to result in a continuous carbide skeleton and that the properties of the sintered composition are thus essen- tially those of the carbide.2 On the hypothesis that this mechanism holds to a greater or less degree in cementing most of the refractory metal carbides with an auxiliary metal, it appears from Table 1 that titanium carbide compositions would offer possibilities for a high temperature material. Titanium carbide has extensive use for supplementing the properties of tungsten carbide in tool compositions. Although the literature contains several references to compositions containing only titanium carbide with an auxiliary metal,3,4,5,6 it may be inferred from the meager data that such compositions were deficient in strength and were considered to have poor oxidation resistance.7 Kieffer, for instance, reports the transverse rupture strength of a hot pressed TiC composition at 100,000 psi as compared to up to 350,000 psi for WC compositions. The work described herein was undertaken to determine the properties of compositions consisting of titanium carbide and an auxiliary metal and to improve the oxidation resistance of such compositions. It appeared possible that the inclusion of one or more other carbides with titanium carbide might improve the oxidation resistance and also that this might be more desirable than other means from the point of view of maintaining the highest possible softening point. Consideration of the available carbides in Table 1 suggests tantalum and columbium carbides because of their high melting points and general refractoriness. The work on improving oxidation resistance was concentrated on the addition of tantalum carbide or mixtures of tantalum and columbium carbide. The auxiliary metals used included cobalt, nickel and iron. It was also desired to learn the general physical properties of these compositions. Experimental Procedure The compositions used in this study were made by the usual powder metallurgy procedure applicable to cemented tungsten carbide compositions. The powdered carbide or carbides and auxiliary metal were milled together out of contact with air. In some cases cemented tungsten carbide balls and in other instances steel balls were used to eliminate any effect of tungsten carbide contamination. A temporary binder, paraffin, was then included in the mix and slugs or ingots were pressed with care to obtain as uniform pressing as possible. The ingots were presintered and the various shapes of test specimens were formed by machining, making the proper allowance for shrinkage during sintering. Thereafter the shapes were sintered in vacuum at temperatures of from 2800 to 3500°F. Final grinding to size was carried out by diamond wheels under coolant. The titanium carbide used contained a minimum of 19.50 pet total carbon and a total of 0.50 pet metallic impurities as indicated by chemical and spectrographic analysis. It was found by X ray diffraction examination with

Jan 1, 1950

By Laurance S. Reid, Joe A. Porter

Gas dehydration plays an important part in the production of natural gas. Effective dehydration prevents formation of gas hydrates and the accumulation of water in transmission Systems,2,6,7 insuring uninterrupted gas deliveries at maximum efficiency under the most adverse weather conditions. At the present time, most gas companies require a maximum water vapor content of seven lb per million standard cu ft of gas. so that virtually all gas tendered for sale must he dehydrated to meet this specification. For a number of years it has been common practice to produce gas and gather it at a common point for dehydration prior to discharge into the transmission system.1,3,11,16,17 However, higher transmission line pressures, long gathering lines and relatively low ground temperatures have made it necessary to dehydrate gas at. or near. individual. wells in order to gather gas from a number of newly developed fields without unusual difficulty. Where gas has been dehydrated at pressures ranging from 300 to 800 psi in the past. future trends indicate that these processes may be operated at pressures as high as 2,000 psi. Economics of gas dehydration are of great importance, partitularly where facilities must he provided to process relatively small quantities of gas, such as the production from an individual well. Although the adsorption of water vapor from gas on a granular sorbent material such as activated bauxite, activated alumina, or one of the alumina-silica gels is highly effective and produces virtually "bone dry" gas, the cost of a small unit of this type is substantially greater than that of an absorption process which, through proper selection of the absorbing liquid, will dehydrate the gas sufficiently to meet pipe line specifications. For this reason, a great deal of emphacis has been placed on the development of small, inexpensive dehydration units8,24 and the search for more effective absorb. ent liquids has been intensified. A wide variety of methods for dehydrating gas are known&apos; and many of these have been used in industry. Earlier applications of the absorption process employed concentrated solutions of calcium and lithium chlorides as the absorbent. The severe corrosion problems inherent in handling these solutions and the relatively small dew point depressions obtained caused early abandonment in favor of, or conversion to. diethylene glycol when it was found that aqueous solutions of this organic liquid were more hygroscopic than the brines and were non-corrosive. Processes employing diethylene glycol-water solutions are widely used for gas dehydration at pressures ranging as high as 1,200 psi.13,14,15 At nominal pressures a dew point depression of 45° to 50°F may be be and the data of Russell et al." indicate that a minimum dew point is obtained from the effluent gas at a pressure of approximately 1,200 psi when the gas is in equilibrium contact with a 95 per cent by weight diethylene glycol solution. In a number of instances the dew point depression obtained with diethylene glycol-water solutions is not sufficient to produce a specification product without cooling the inlet gas. In a recent search for a better absorhent, triethylene glycol was used in a small commercial dehydration unit and subjected to rather exhaustive field tests.&apos; The data obtained were encouraging and indicated that, at pressures ranging from 300 to 500 psi, triethylene glycol porduced a substantially greater dew point depression than diethylene glycol. These results led to an investigation of the system natural gas-water-triethylene glycol in an effort to obtain vapor-liquid equilibrium data, to determine pressure limitations, and to develop other data pertinent to the design of gas dehydration processes. A review of the literature has failed to reveal any data which permit reasonably accurate calculation of the vapor-liquid equilibrium conditions for a solution of water and triethylene glycol in contact with natural gas at high pressure. Since these constituents form a non-ideal system, the Poynting equation18,21 or the usual combination of Raoult&apos;s and Dalton&apos;s laws19,20,22 would not be valid. Correction of Raoult&apos;s and Dalton&apos;s laws by the use of activity coefficients2&apos; is not feasible for available data are insufficient for the prediction of the actual increase in the ratio of the activity of one component in the vapor phase to its activity in the liquid. Therefore. experi-

Jan 1, 1950