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1. What Is a Rock Burst? . . . . 569 Jack Spalding . . 569 A. F. Robertson . 569 W. R. Crane . 569 G. S. Rice......569 P. J. Shenon........... 569 L. C. Graton........... 569 2. What Are the Causes of Rock Bursts? 573 Jack Spalding..........573 A. B. Yates and P. J. Shenon 574, 578, 592, 596 A. F. Robertson . . . . . 575, 595 W. R. Crane. ... 579 G. S. Rice.........582 Oscar Weiss .........582 P. B. Bucky..........582 P. H. Bird.....588, 592, 593, 595 M. K. Hubbert.........593 G. Wheeler.......... .593 B. F. Tillson........593, 595 T. T. Read............594 3. How Can Rock Bursts Be Prevented?. 597 Jack Spalding..........597 A. B. Yates and P. J. Shenon ... 598 A. F. Robertson.......599 W. R. Crane....... .602 G. S. Rice............602 Page 4. How Can Rock Bursts Be Predicted?. 602 Jack Spalding.........602 A. F. Robertson.......602, 603 A. B. Yates and P. J. Shenon ... 602 W. R. Crane......602 G. S. Rice......602 B. F. Tillson...........603 5. How Can Rock Bursts Be Controlled? 603 Jack Spalding..........603 A. F. Robertson.......603 W. R. Crane...........604 A. B. Yates and P. J. Shenon 604 Oscar Weiss........605 G. S. Rice......- 604, 609 R.D.Hoffman..609, 610 R. D. Hall..........609 R. H. Cromwell . . 609 P. J. Shenon...........609 P. B. Bucky......609, 611 B. F. Tillson.........609, 611 A. B. Yates...610, 611 P. H. Bird.......610 6. General Discussion........ 611 Jack Spalding.......... 611 R. D. Parker....... . 616 C. Baring Horwood........ 618 P. B. Bucky........... 619 Foreword This symposium brings together points of view, experiences and ideas on rock bursts from a goodly portion of the globe. Some conceptions, particularly those regarding the necessity of depth, have been fairly well shattered, as we find that they are present in the water tunnels of New York, on the surface at marble quarries in Vermont, and in the coal mines of the United States, as well as in the deep mines of the South African and Kolar gold fields, and in the nickel, copper and gold mines of Canada. Their occurrence under such a variety of conditions is, therefore, a challenge, which, if successfully met and overcome,

Jan 1, 1946

By Thomas M. Plouf

Getting optimal performance from flotation cells can, in many cases, be critical to a project's economic viability. Simple testing procedures can sound early warning signals as well as maintain optimum recoveries from the flotation cycle. The materials required for a simple testing laboratory include: (1) pH meter or pH paper, (2) bottles of reagents used in plant flotation, (3) stop watch, (4) calibrated eye droppers. (5) laboratory flotation machine (1000-g tank, open impeller), (6) froth collection pans, (7) magnifying glass, (8) sizing screen sufficient to retain 10% of the flotation feed coarse fraction, (9) sizing screen for the size particles at which desliming of the plant flotation feed is to take place, and (10) a set of screens covering the complete range of feed particle size.

Jan 4, 1978

By R. L. Perrine

The rise of drain holes drilled from a well to improve productivity is becoming increasingly common. This paper presents data on the productivity increase that may he expected. The data were obtained by use of an electrolytic tank mode1 of a reservoir. Parameter varied in the study to show their effect on productivity include the length, number, and arrangement of drain holes, formation thickness, and damage near the well-hore. The most important results are that very large increases in productivity can be expected only ill damaged wells. The distance, to which drain holes penetrate is of primary importance. Additional length is more effective than increasing the number of drain holes. INTRODUCTI O N In planning the use of drain holes to improve productivity, it is important to he able to estimate the increase in production that can be obtained for a given expenditure. It is also important to know what combination of parameters related to the use of drain holes can he chosen to give the largest production increase. This paper presents data on the productivity increase that may be expected, as obtained by use of an electrolytic tank model of the reservoir. In this study, :! number of parameters were varied to show their effect on productivity. These included the length, number, and arrangement of the drain holes. The presence or absence of a damaged zone of low permeability around the well-bore and the thickness of the producing formation were also considered. The productivity increase that might be expected due to drain holes is presented as the ratio: productivity of a well after drain holes are drilled and completed to the productivity of the same well in an undamaged state without drain holes. The symbol Q/Qo is used to represent this productivity ratio. Thus, the comparison in each case is with a formation of uniform and undamaged permeability. Additional notation includes I;, for the radial extent of the damaged zone, which is assumed to be cylindrical and concentric with the wellbore. Thus the effect of an actual block is approximated by a discontinuous varia-tion in permeability. For purposes of this paper, the permeability within the damaged zone, denoted by kb, is assumed to be 1/25 that in the remainder of the formation, or k. A necessary assumption in making comparative tests using an electrolytic model is that reservoir flow behavior can be approximated by single-phase, steady-\tate flow according to Darey's Law. In addition, the formation must be assumed to be homogeneous with equal horizontal and vertical permeability. The well-hore diameter in this study is assumed to be 11¾ in. and the drainage radius of the well equal to 500 ft. The drain holes are considered to have been completed without damage. THE ELECTROLYTlC MODEL 'She producing formation was modeled by forming a sheet of phosphor-bronze into a cylinder 40% in, in diameter to represent the boundary of the drainage area. This was enclosed in a waterproofed plywood box, and the box filled to an appropriate level with a dilute sodium chloride solution. Solution concentration was adjusted to give a total resistance from

Jan 1, 1956

By Morris Muskat

THE method of R. W. Moore1 for determining subsurface interfacial depths by means of integrated curves of apparent resistivity has been analyzed theoretically. It is found that the only unique tangents that can be drawn to such curves are the asymptotes at infinite electrode spacing and the tangents through the origin at vanishing electrode spacing. Explicit expressions have been derived for the relationship between the electrode spacing at the points of intersection of these tangents and the thickness of the surface strata as a function of the conductivity parameters for the two-layer and three-layer earths. It is found that in all cases the electrode spacing at the points of intersection will exceed [3/2] of the thickness of the surface layer, and may even become indefinitely large as the resistivity of the deepest layers increases as compared with that of the surface layer. These results do not agree with the empirical findings of Moore that the intersection of the tangent lines fall at an electrode spacing very approximately equal to the thickness "of the surface layer.

Jan 1, 1944

By Joseph S. Malesky

As essential as the discovery of coal was to our state of advancement, the discovery and development of explosives marks one of the most important findings in the history of civilization. For this reason explosives are rightfully referred to as the forerunner of progress. Without explosives our vast economic enterprise concerning the mining of coal, copper, iron, aluminum, and various other ores could not function. Explosives are used in all kinds of construction works, in the razing of old buildings, blasting of trenches, driving of tunnels, and in many other instances common to our everyday life. An explosive may be defined as a substance (usually a mixture) that, where flame or shock is applied, yields readily to rapid combustion or oxidation, accompanied by the formation of such relatively large quantities of gases as to produce much violence and pressure which, in turn, react against their surroundings and cause what is termed an explosion. By their very nature the action of explosives is destructive and disruptive of adjacent materials. Decomposition of explosives can occur through deflagration, which is rapid burning or combustion, as in the case of black powder, or through detonation, which is an almost instantaneous disruption, as in the case of dynamites and blasting agents. HISTORY OF BLASTING WITH EXPLOSIVES At one time workmen obtained stone blocks for building by grooving the rock with crude picks, driving wooden wedges into niches in the rock, and pouring water on the wedges; the swelling of the wood forced out the blocks. As late as the 17th century, fires were placed against the face of rock to crack it, and water was sometimes dashed on the heated rock to shatter it by sudden cooling. The progress of our country is synonymous with advancement of the improved manufacture and extended use of explosives. Coal had been

Jan 1, 1973

By Rossiter W. Raymond

I DESIRE to call the attention of the Institute to a novel system of dredging, which, it seems to me, may prove applicable, not only to river and harbor improvements, but also to certain varieties at least of alluvial and diluvial gold mining; that is, river-mining, barmining, coast-mining, and any other similar operations now carried on by means of coffer-dams or dredging machines. The simple and effective method to which I refer is the invention of General Roy Stone, formerly an officer of volunteers, and at present a civil engineer, engaged under General Newton, of the United States Engineer Corps, upon the government works in New York harbor. General Stone has been, since September, 1878, in charge of operations upon Diamond Reef. This reef, lying between Governor's Island and the Battery, is one of the most dangerous in the harbor. Its position in the highway of navigation, and the fact that it is dangerous only to vessels of considerable draught and at certain stages of the tide, combine to increase the serious nature of the disasters which it has caused. The reef consists partly of rock in place, and partly of deposits of glacial clay, boulders, and pebbles, over all of which lies, or did lie until it was removed, the ordinary silt and rubbish of the harbor. As the purpose of the present paper has nothing to do with the special dimensions and other circumstances of this particular work, I describe those features only which are connected with General Stone's ingenious device. Various attempts have been made to remove the upper portion of Diamond Reef and secure a navigable depth at low tide. Some years ago Maillefert undertook to accomplish this by firing charges of high explosives, simply laid upon the surface. He accomplished some good in the removal of projecting points and ridges ; but as soon as the surface of the reef had become approximately level, his method was no longer effective. After the work had been taken up by the Engineer Corps, the well-known drilling-scow invented by General Newton was brought into action ; and, so long as holes could be bored and fired in solid rock, this process was effective enough. In the mixture of hard-pan

Jan 1, 1880

By Howard M. Wells

The investment worth of a mineral deposit can only be realistically evaluated in relation to specified engineering design criteria which fully detail the proposed method of exploitation. The operational design of a mine falls essentially within the technical discipline of the mining engineer, under the constraint that the technical design should be aimed at optimizing the financial attractiveness of the project. In the case of a marginally viable proposition it becomes vitally necessary to identify the best set of design parameters which together will add up to an optimum investment proposal. This paper examines some fundamental logic of optimization for a "wasting asset" type of investment such as a mine, with special reference to the rate of annual production and the strategy of selective mining.

Jan 1, 1979

By W. A. Wood, H. L. Wain, R. I. Garrod

The mechanical behavior of recrystallized chromil~m of high purity has been studied, principally in torsion and to a lesser extent in tension, at temperatures between —196oand 350oC. Depending upon the conditions of test, the material may show brittle or ductile behavior or an intermediate or subduc-tile state having some of the characteristics of each. This latter state existed at temperatures between approximately ±50°C and was characterized by a) extensive creep at stresses well below the normal fracture stress, b) nonelastic loading/unloading effects during creep, c) strain softening under cyclic loading, and d) final failure of a brittle type. Suggestions are made on the dislocation processes and interactions which give rise to subductile behavior The ductile-brittle transition in bee metals has been studied mainly by tension and bend tests. These methods, however, favor crack propagation which may follow too closely on initiation for detailed study of the transition itself. For work of this nature, therefore, other modes of deformation less favorable to crack propagation may be preferable. This paper describes a study of the ductile-brittle transition in chromium which is based mainly on torsional testing although a few subsidiary experiments were made in tension. It appears to reveal at the transition an intermediate state that cannot properly be described as either brittle or ductile. Torsional tests on chromium have been made by other workers1 but not, as here, primarily for study of this intermediate state. EXPERIMENTAL The chromium, in the form of swaged rod, was prepared by techniques already described.' The particular material used was one in which the main impurities were 0.03 wt pet 0 and 0.006 wt pet N and one in which transition from ductile to brittle states in torsion conveniently fell at about room temperature. For torsion, test specimens were from 5/16-in.-diam rod to provide test portions 1-1/4 in. long by 7/32 in. diam, a twist of 1 deg thereby corresponding throughout this paper to 0.0015 surface shear. The specimens before test were annealed for 2 hr at 1200°C in vacuo, which left them with a re-crystallized grain size of about 0.01 mm, and then electropolished. They were tested under dead-weight loading in an apparatus in which they could be surrounded by a furnace or cooling chamber, tests in practice being made at various temperatures between -196" and +350°C. For tension tests, cylindrical specimens were prepared in a similar manner and tested at room temperature under dead-weight loading. RESULTS (TORSION) Subductile State. The state described above as intermediate between brittle and ductile may be perhaps best defined by reference to torque/twist curves at various temperatures. These are grouped in Fig. 1. Below about -50°C the material was brittle, in the sense that it exhibited little plastic deformation under stress and fractured by cleavage along planes of maximum resolved tension, which in torsion produces the well-known helical type of fracture. The deformation is typified by the curves for -196" and -150°C in Fig. 1; it shows a slight but progressive deviation from linearity above a certain torque, here about 50 lb-in., until fracture occurs at about 95 lb-in. A feature to which it is desired specially to call attention is that under none of the loads did the specimens show significant creep.

Jan 1, 1964

By Leonard L. Melton, Calvin D. Saunders

The design and performance of many operations common to the petroleum industry depend upon the unique properties of a class of materials known as non-Newtonian fluids. The art of measuring and describing these properties, called rheology, has fallen far behind the field applica-tion of these fluids in this industry. Empirical methods are still employed although theoretically sound methods of analysis are now available. This paper illustrates a completely general method of analysis of the rheological properties of non-Newtonian fluids which id independent of the type of viscometer employed and also the rheological type of fluid encountered except those of a thixo-tropic or rheopectic nature. Values of the rheological properties of a fluid obtained using this method of analysis are based upon an absolute scale of measurement, eliminating the necessity of employ-jng arbitrary concepts of the flow properties of non-Newtonian fluids, The fundamental nature of this method of analysis is further demonstrated by evaluating the precision with which measurements have been made of these rheological properties by employing a dimensionless criteric: —the Fanning friction factor-Reynolds number correlation. INTRODUCTION Non-Newtonian fluids are not new in the petroleum industry. Particular properties of non-Newtonian materials have been recognized and used to advantage in drilling fluids and have found excellent application in the hydraulic fracturing process.'.' While usage of these fluids is not new in this industry, the art of measuring and describing their rheological properties is still in its infancy. This is reflected in the accepted method of evaluating drilling fluids, API RP 29, (1950), which recommends a one point "viscosity" measurement. These shortcomings are recognized by various groups in the industry and more adequate methods have been prposed.3,4 The efforts Of these people are to be commended; but, at the same time, the limitations of their method of analysis and viscometer must be appreciated. This method Of analysis is applicable Only to Bingham plastic fluids as is pointed out early in their articles. The consistency of a Bingham plastic fluid must also lie within the range of the viscometer which is also well defined by the author. It is believed that the apparent simplicity of this method of analysis and the utility Of Operation Of their viscometer will soon make the terms non-Newtonian fluid and Bingham plastic fluid synonymous as used in this industry; a tendency which has already been encountered. Application of this method of analysis to a non-Newtonian fluid other than a Bingham plastic can lead to erroneous results. The field of rheology has long been hampered by the adherence to arbitrary concepts of Of of the flow properties Of non-Newtonian fluids. This has resulted in the design and operation of viscometers so as to fulfill these concepts rather than following the more logical method of analyzing experimental data so as to yield a fundamental truth. completely Bingham proposed the concept Of plastic flow and yield asu rement. data presented by Buckingham could hardly be interpreted so as to substantiate this theory; but rather succeeded in establishing the fact that compliance with this flow concept could never be realized in the capillary tube vis-cometer.5 Bingham, in reply, sug-gested "Rather than complicate our formula, it would seem to me a much better plan to so change the conditions of flow that the formula will be linear... Reiner0 stated .This plan has been followed by me in collaboration with Miss Riwlin. . . . From the present paper (Reiner and Riwlin, 1929) it will be seen that it is possible to choose the conditions of flow so that the formula based on Bingham's law of plastic flow remains linear. This is realized in the rotation viscometer," Thus, a viscometer, with design and operation based on the Reiner and Riwlin equation for plastic flow, is restricted to a specific range of flow

Jan 1, 1958

By Vincent Carlsson

A comprehensive investigation has been undertaken to clarify how pellets are affected by alkali circulating in the blast furnace. The investigation has been performed with acid and basic pellets in a special furnace. Experiments were carried out to ascertain the influence of potassium on swelling and reducibility when added at different stages of reduction. After that, the significance of the quantity of potassium added in the hematite stage was studied. A parallel experiment with sodium as the alkali component was also con- ducted. Besides these vaporization experiments the effect of alkali on softening and reduction characteristics at high temperatures was investigated. The results showed that alkali always increases swelling, especially when added in the hematite stage. The addition of alkali increases reducibility of acid pellets during reduction from wustite to 70 % reduction. The softening temperature is significantly lowered by the addition of alkali and is, in any case, lower for acid pellets than for basic pellets. The microscopic studies showed that alkali ferrites can be formed irrespective of the influence of alkali on the slag phase.

Jan 1, 1977

By Paul H. Price, John P. Nolting

The history of the salt industry in West Virginia dates back nearly two hundred years; howTever, the history of salt as an important raw material for the chemical industry is much more recent. The earliest record of West Virginia salt was in 1753, when a raiding party of Shawnee Indians attacked frontier settlements in Virginia taking captive a number of the pioneers. One of these, who later escaped and returned to her friends, described how the Indians camped at a salt spring on the banks of the Kanawha River and evaporated the water to obtain a supply of salt to take back to Ohio with them. Settlement of the Kanawha Valley began in 1774, that same year the Battle of Point Pleasant ended the Indian's power in the Ohio Valley; and settlement of the Kanawha Valley progressed rapidly with a consequent increase in the importance of the Kanawha Licks as a source of salt. In those days the evaporation of the brine was a family matter for which the family wash-kettle was commandeered. In 1797, Elisha Brooks erected the first salt furnace in the Kanawha Valley. It consisted of two dozen small kettles set in a double row, with a flue beneath, a chimney at one end, and a fire bed at the other. He obtained his brine at a depth of 20 to 30 ft by sinking hollow logs, called "gums" into the salt lick and dipping the brine with a bucket. His production was about 150 lb a day and sold for 8 to 10 cents a pound. In 1806, the Ruffner brothers, David and Joseph, prospected for and drilled the first well in America using a spring pole and steel chisel bit. After several failures they succeeded, in 1808, in drilling to a total depth of 59 ft where they secured a good flow of strong brine. Most standard drilling tools, jars, casing, and practically all the basic oil well drilling machinery now in use, were developed in the drilling of salt wells. To evaporate this brine, the brothers built a wood-burning furnace similar to that of Brooks but with a better arrangement and with more and larger kettles. When production was started they reduced the price of salt to 4 cents a pound. By 1817, there were some 30 salt furnaces in the Kanawha area. It was in this year that bituminous coal first was used as an industrial fuel. David Ruffner again pioneered the way by converting his furnace for the consumption of coal. This year also brought about the formation of the first trust which controlled production and set a price of 1 cent a pound for the salt.

Jan 1, 1950

By Milton Williams

A comparison is made between the amount of interstitial water found by analysis in cores and that estimated from the resistivity curve of the electric log for the corresponding strata of producing reservoirs. It is shown that while the determined and the estimated water saturations are in good agreement in some cases, this agreement may be due to a fortuitous compensation of errors. Estimates of water saturations made from the electric 1og by use of existing relations should, therefore, be employed with caution. Also presented are data on the variation of salinity of interstitial waters in reservoir sands, and on the effect of variation of salinity and porosity on the validity of estimates of water content made from the electric log. INTRODUCTION Throughout the history of electric logging there have been recurrent cycles of optimism and pessimism as to the value of the electric log in the quantitative estimation of reservoir fluid content. The very early days of electric logging were an optimistic period, in which there was widespread faith in the ability of the resistivity curve to reflect fluid content, and in the ability of the potential curve to indicate textural characteristics. In time the accumulation of exceptions to this idealistic behavior brought about a general disillusionment, and caused the more pessimistic of those dealing with electric logs to believe that the sole importance of the log lay in stratigraphic correlation. Within the last several years optimism as to the quantitative use of the electric log has been revived, primarily as the result of the stimulating work of C. E. Archie' on the estimation of interstitial water in sands from resistivity data. Even though the general trend of thought on the quantitative value of the electric log reflects optimism, it is inevitable that there are some widely divergent opinions of the validity of quantitative estimates based on the electric log. A valid method of estimation of fluid content by means of the electric log and a general knowledge of the textural character of the reservoir rock would be of signal importance, not only in that it would save time and money in securing information on reservoirs now being drilled, but also because it would permit the evaluation of reserves in many fields drilled without adequate core data subsequent to the advent of electric logging. Because of this importance, Humble's Production Research Division, in cooperation with various other company divisions, initiated several years ago series of tests designed to evaluate the reliability of estimates of fluid content made from the electric log. The investigation was limited at the outset to sand reservoirs, since it was felt that the inclusion of limestone reservoirs would entail needless complications. In devising these tests it was immediately apparent that the chief difficulty in evaluating the worth of any method of estimation lay in establishing the true value of fluid content. The results of direct analyses of cores cut with ordinary mud were not sufficient, because of the probability of contamination of the fluids by filtrate from the drilling mud; the results of restored state tests on cores were deemed unsuitable because these results can hardly be said to furnish a primary standard. The method adopted was the direct analysis of cores cut with an oil-base drilling fluid. Such cores, when properly handled, are believed to afford the most precise determination of water content available at the present, and, in addition, lend themselves readily to the determination of various other properties which are pertinent to the estimation of fluid content from the electric log. Since it was desired to compare the fluid contents estimated from the electric log run in ordinary mud with cores cut in the same hole, the use of oil-base fluid necessitated the changing over, after all cores were cut, to a conventional mud. This procedure presented several advantages, one of which was that the use of oil-base fluid permitted

Jan 1, 1950

By Michael Tenebaum

IN a previous investigation1 the authors studied the effect of pressure on the reduction of iron ores by hydrogen. With hydrogen as a reducing agent, the rate of reduction was increased substantially by increasing the pressure from 1 to 2 atmospheres. The results with hydrogen prompted the present study of the effect of pressure on reduction with carbon monox-ide and with mixtures of carbon monoxide and nitrogen. FEATURES OF REDUCTION PROCESS The gas stream in the lower part of the blast furnace always contains sufficient concentrations of reducing gases to complete reduction provided sufficient time is allowed for the reaction to proceed. Reducing gases react immediately with the iron oxide on the surface of lumps of ore. However, as the unreduced surface recedes from the easily accessible exterior of the lump, the reaction proceeds by virtue of the diffusion of the gases into and out of individual pieces. The rate of diffusion of gases, which undoubtedly plays an important role in the reduction of iron ores, depends on several factors, most impor-tant of which are: (1) molecular weight or density, (2) pressure, (3) tem-perature, (4) concentration gradient. Thus, the rate of reduction of a lump of iron ore at any temperature will depend not only on the specific reaction rate but also upon: (1) available surface of unreduced iron oxide, (2) rate of diffusion of the reducing gas to the reacting surface, (3) rate of effusion of the gaseous products of the reaction from the reacting surface, (4) adsorption of the gases on the reacting surface.

Jan 1, 1939

By Rossiter W. Raymond

I desire to call the attention of the Institute to a novel system of dredging which, it seems to me, may prove applicable, not only to river and harbor improvements, but also to certain varieties at 1east of alluvial and diluvial gold mining; that is, river-mining, barmining, coast-mining, and any other similar operations now carried on by means of coffer-dams or dredging machines. The simple and effective method to which I refer is the invention of General Roy Stone, formerly an officer of volunteers, and at present a civil engineer, engaged under General Newton, of the United States Engineer Corps, upon the government works in New York harbor. General Stone has been, since September, 1878, in charge of operations upon Diamond Reef. This reef, lying between Governor's Island and the Battery, is one of the most dangerous in the harbor. Its position in the highway of navigation, and the fact that it is dangerous only to vessels of considerable draught and at certain stages of the tide, combine to increase the serious nature of the disasters which it has caused. The reef consists partly of rock in place, and partly of deposits of glacial clay, boulders, and pebbles, over all of which lies, or did lie until it was removed, the ordinary silt and rubbish of the harbor. As the purpose of the present paper has nothing to do with the special dimensions and other circamstances of this particular work, I describe those features only which are connected with General Stone's ingenious device. Various attempts have been made to remove the upper portion of Diamond Reef and secure a navigable depth at low tide. Some years ago Maillefert undertook to accomplish this by firing charges of high explosives, simply laid upon the surface. He accomplished some good in the removal of projecting points and ridges; but as soon as the surface of the reef had become approximately level, his method was no longer effective. After the work had been taken up by the Engineer Corps, the well-known drilling-scow invented by General Newton was brought into action; and, SO long as holes could be bored and fired in solid rock, this process was effective enough. In the mixture of hard-pan

Jan 1, 1880

By Alan J. Strauss

The Group IV elements germanium, tin, and lead form nine 1:1 compounds with the Group VI elements sulfur, selenium, and tellurium. This paper reviews the properties of the pseudobinary solid solutions formed by these compounds, including the extent of mutual solid solubility, temperature-composition phase diagrams, transport properties, deviations from stoichiometry, optical properties, and energy band structure. Particular emphasis is placed on the Pbl-xSnxTe and Pb1-xSn,Se alloys with rocksalt structure, because of current interest in these malerials for generating and detecting infrared ,radiation. ThE Group IV elements germanium, tin, and lead form nine 1:1 compounds with the Group VI elements sulfur, selenium, and tellurium. Some of the physical and electronic properties of these compounds, including their melting points1-8 and energy gaps,4'9-12 are listed in Table I. Four compounds (SnTe, PbS, PbSe, and PbTe) have the cubic rocksalt (Bl) structure. At room temperature GeTe has a rhombohedra1 structure closely related to the B1 structure, into which it is transformed at about 400°C. Four compounds (GeS, GeSe, SnS, and SnSe) have the orthorhombic B29 structure. In samples which have not been intentionally doped with impurities, the electrical conductivity is due primarily to electrons or holes produced by the ionization of donor or acceptor lattice defects associated with deviations from stoichiometry. Undoped samples of PbS, PbSe, and PbTe may be either n type or p type, depending on whether they contain excess lead or an excess of the Group VI element, respectively, but only p-type samples of the other compounds have been reported. This paper will review the properties of the pseudo-binary solid solutions formed by the nine 1:l compounds. The topics to be considered include the extent of mutual solid solubility, temperature-composition phase diagrams, transport properties, deviations from stoichiometry, optical properties, and band structure. Particular emphasis will be placed on the Pb]-xSnxTe and Pbl-xSnxSe alloys with B1 structure, which are promising materials for generating and detecting infrared radiation in the 8 to 14 µm atmospheric window and beyond. MUTUAL SOLID SOLUBILITY The extent of mutual solid solubility in the pseudo-binary systems has been investigated for fourteen of the eighteen ternary systems (in which the two terminal compounds have a common element) and for nine of the eighteen quaternary systems. In most cases, X-ray diffraction measurements made at room temperature were used to determine the structure and lattice parameter(s) of the phase(s) present in samples of various compositions prepared by freezing from the melt. In many investigations, including the extensive studies of Krebs and co-workers,13'14 the samples were annealed at elevated temperatures before X-ray measurements were made. In some cases, metallographic examination and thermal analysis have also been employed. The results for the ternary and quaternary systems are summarized in Tables II and III, respectively. (The original references should be consulted for the annealing temperatures.) The solubility of one compound in the other is at least 5 mol pct in all cases, and is often much larger. Complete solid solubility has been observed in all systems so far investigated in which the terminal compounds have the same structure, although in the PbS-PbTe system complete solubility is limited to elevated temperatures. Thus complete solid solubility occurs in five systems where both compounds have the B1 structure (SnTe-PbTe, PbS-PbSe, PbS-PbTe at temperatures above 805°C, PbSe-PbTe, and SnTe-PbSe) and in three where both compounds have the B29 structure (GeS-SnS. GeSe-~n~e-, and SnS-SnSe), as well as in two involving GeTe and a compound with B1 structure (GeTe-SnTe and GeTe-PbTe). On the basis of thermal analysis data, complete solid solubility at sufficiently high temperatures has also been reported for the GeSe-GeTe2 and SnS- pbS22 systems. This seems unlikely, however,

Jan 1, 1969

By Cloyd M. Smith

B. F. TiLLson*— The manifold difficulties of accurate anemometry in irregular sections of mine passageways, the irregular distributions of velocities in cross sections of the same, and the disturbing influence of the observer upon the air flow, all indicate an undesirable inaccuracy of results obtainable by any standardized method of traversing the section by an anemometer. It seems obvious that another, and simpler, method should be used to determine the volume of air flow in mine passages, namely: 1. At appropriate locations cement or calked framework rings should be installed permanently to equalize the irregularities of sectional contour and provide a place and means of attachment for a temporary cloth brattice which bears a rigid orifice. 2. The measurement of the velocity of air flow through the orifice may then be by anemometer or, preferably, by Pitot tube measurements of the differential pressures on both sides of the orifice in accordance with the standard practices available in engineering 1iterature. † The constants may be determined for various measuring positions in relation to the resulting "vena contracta." 3. The position of the person who makes the measurements is behind the brattice out of the air stream. The Pitot tube does not offer as disturbing an obstruction as the anemometer. A recording gauge may be employed to integrate fluctuations in air flow through that portion of the mine. No traverses are required because the reading may be at a single central point. An anemometer can be used with an orifice flow. The orifice will increase the air velocity at the measuring point, with correspondingly more accurate measurements where the normal air velocity through the passageway is low. Portable brattices might be devised with the cushioning rims which would seal against irregular rock surfaces where permanent rings were not available or feasible. The development by the Ventilation Committee of standard procedures and devices for the orifice measurement of the flow of mine ventilating air might be a desirable project for this coming year. C. M. Smith (author's reply)—Thank you for your discussion of my paper on underground anemometry. Your suggested method of measuring underground air flow is a novel one which might be applicable in some situations. It should be tested along with other suggested methods in any investigation of this subject. G. E. McElroy*—In spite of the adverse publicity that vane-anemometer methods of air measurement have had in the past and that contributed by the present paper, I endorse Mr. Erickovic's statement that anemometer traversing "has proved to be widely applicable, expeditious and simple" and add that available methods are accurate enough for the purposes for which they may be used. The fact that the great majority of minor mine officials assess relative changes in rates of air flow by comparison of crude vane-anemometer measurements, known to average 20 to 30 pct high, has no important bearing on this subject, because state inspection standards were based originally on such methods of air measurement. Federal inspection standards are based on actual rates of flow as determined by traversing, and interest in traversing methods is rapidly increasing. In considering traversing methods, three aspects are of major importance: (1) the absolute accuracy of calibrations; (2) the degree of interference with normal flow conditions introduced by traversing methods designed for accurate measurement by shaft-mounted instruments; and (3) the proper "method" factor to use for approximate measurements by hand-held instruments. With respect to absolute accuracy of calibrations, we have always placed reliance on calibrations made by the National Bureau of Standards, with which manufacturers' calibrations have usually agreed very closely. It is therefore particularly disturbing to find7 that calibrations made previous to June 1947 are presumably about 5 pct in error because of excessive registry caused by the thin flat plates on which anemometers were mounted for calibration. Velocities corrected for calibration have therefore averaged about 5 pct low in all probability. In this connection, it is interesting to note that an anemometer calibrated against Pitot-tube measurement by a single-point method in the Bureau of Mines experimental coal nine in 1923 indicated this same difference of about 5 pct and that the same instrument calibrated by a traversing method in a metal mine some months later indicated a difference in the same direction of about 4 pct. These results are reported by the Bureau of Mines.8 Regarding the degree of interference, or changes in velocity distribution, caused by the position of the observer's body in traversing operations, misconceptions seem to be especially prevalent, resulting in increasing advocacy of methods, such as the "clear section" method outlined in this paper, that cause just the type of interferences that they are designed to avoid. The degree of interference for any method may be gauged easily by a few experiments with a velocity-pressure gauge connected to a Pitot tube or with an indicating velocity meter such as the Velometer. In an experiment cited by McElroy and Richardson,# a decrease of 5 pct was noted at ten widths upstream from a 6-in. plank, whereas an observer's body at about the maximum practical distance of 6 ft downstream from the instrument is only about four widths away. In the Bureau of Standards paper previously mentioned, it is recommended that supports used in calibrations be at least 16 widths downstream. In practice, therefore, a downstream position of the observer is ruled out as far as accurate measurement is concerned. Operation of the anemometer by rigid shaft support from a point outside the section is seldom practicable; however, accurate results can be obtained, with the anemometer rigidly attached to a short shaft and held at arm's length, by an observer advancing across the traversed section while he faces the opposite wall and stands sideways to the current, provided that he keeps the instrument at least 3 ft away from his body at all times and traverses the entire section with it. If the traverse can be started with the observer in a side recess, the entire section can be covered in one operation. Normally, it would be covered in two half-sections. The presence of the observer's body does not, as is commonly supposed, increase the average velocity throughout the remaining part of the section. Rather, the velocities 1 to 2 ft on either side of his body are increased, but the distribution of velocities throughout the rest of the cross section remains normal, and a traverse made as stated gives a true average velocity for normal-flow conditions. Regarding the proper "method" factor for accounting for interference in the approximate methods of traversing with hand-held instruments, here again confusion prevails, for which the writer must assume some of the blame. Comparison of consecutive traverses made by shaft-held and hand-held 4-in. anemometers in field work after the tests reported by McElroy and Richardson' gave method factors

Jan 1, 1950

By E. R. Parker, D. L. Martin

During the heat-treatment of silver specimens for tensile tests it was observed that the bars blistered and became brittle when heated in a hydrogen atmosphere. To check this unexpected result, a wide variety of commercial silvers were heated in hydrogen at 850°C. Only a few of the materials developed blisters, the most severe of which is the tube pictured in Fig. I. The microstructure of a cross section of the tube is shown in Fig. 2. The embrit-tlernent is extremely severe at the edge; the blisters result from the severe deformation of the surface material by large under- lying gas pockets. The effects resulting from hydrogen embrittlement of silver have been observed by numerous investigators over a long time l,2,3 although it was only recently that a clear explanation was offered.4 However, the damage resulting from hydrogen embrittlement has not been generally recognized; and it is of advantage to know more about this phe- 1 References are at the end of the paper.

Jan 1, 1943

By D. L. Martin, E. R. Parker

During the heat-treatment of silver specimens for tensile tests it was observed that the bars blistered and became brittle when heated in a hydrogen atmosphere. To check this unexpected result, a wide variety of commercial silvers were heated in hydrogen at 850°C. Only a few of the materials developed blisters, the most severe of which is the tube pictured in Fig. I. The microstructure of a cross section of the tube is shown in Fig. 2. The embrit-tlernent is extremely severe at the edge; the blisters result from the severe deformation of the surface material by large under- lying gas pockets. The effects resulting from hydrogen embrittlement of silver have been observed by numerous investigators over a long time l,2,3 although it was only recently that a clear explanation was offered.4 However, the damage resulting from hydrogen embrittlement has not been generally recognized; and it is of advantage to know more about this phe- 1 References are at the end of the paper.

Jan 1, 1943

By H. T. Sumsion, A. U. Seybolt

The results of an investigation of vanadium-rich V-O solid solutions are presented, indicating the structure and lattice parameters of two solutions, a and ß, and their approximate temperature-composition existence. The a solution is the terminal body-centered cubic one, and contains up to 3.2 atomic pct 0. The ß solution has an ordered body-centered tetragonal structure, is formed at 1270°C, and exists from about 15 to 22 atomic pct 0. From the evidence available, the various phase boundaries have no appreciable temperature dependence. Evidence has been found for a polymorphic transformation in pure vanadium at 1550°C. IN an earlier investigation' dealing with the preparation of pure vanadium by calcium reduction of the oxide, it was found that small amounts of oxygen drastically reduced the ductility of the metal. Because this effect was so marked, it was decided to make a study of the solubility of oxygen in solid vanadium. This report deals principally with this solubility and the nature of the phase relationships in the vanadium-rich region, particularly at temperatures below 1300 °C. However, during the investigation enough data on the V-0 system were obtained to make it appear worthwhile to present a tentative phase diagram up to the composition VO. The only significant prior work found on this system are the contributions of Klemm and Grimm,' and Mathewson et al.3 Klemm and Grimm prepared a wide range of V-O compositions by powder techniques including the compositions VO.l, VO.2, VO.3 and VO4 (9.1, 16.8, 23, and 28.6 atomic pct 0, respectively). The first three compositions were found to consist of a body-centered tetragonal solid solution, while the last also showed lines of VO (NaCl structure). They found that the parameter c, increased and the parameter a, decreased with increasing concentration of oxygen. For their composition VO.27, or about 16.8 atomic pct O, they cite the values a, = 2.948A, c, = 3.53A, and c/a = 1.2. Klemm and Grimm made no attempt to determine the solid solubility limit nor to construct a phase diagram. They did, however, give some data on the homogeneity range of VO, and they proposed a structure for the body-centered tetragonal solid solution; these points will be taken up later. Materials and Preparation of Samples The vanadium used in this investigation was prepared in the laboratory by the method previously mentioned.' A typical analysis is as follows: Fe, 0.007 pct; Si, 0.02; Ca, 0.06; C, 0.224; O2, 0.044; N,, 0.0017; H2, 0.003; and V, 99.34 ±0.3 (assay). The vanadium assay is probably low by about the error given. The impurities total about 0.36 which, if subtracted from 100, gives a purity of about 99.6. At the time material was being prepared for this work no suitable technique was available for melting vanadium without appreciable contamination. The procedure adopted therefore was to cut the calcium-reduced regulii into slices which were then rolled to strip about 0.025 in. thick for oxygen diffusion. Pieces of rolled vanadium of approximately 0.025xY4xl in. and weighing about 0.3 g were suspended in a vertical fused-silica tube which was part of an ordinary gas absorption apparatus. The silica tube was heated by an electric resistance-tube furnace which could be raised around the silica tube or lowered away from it as desired. This apparatus had no novel features which require detailed description. Other than the silica tube and furnace, it consisted of a glass system evacuated by a liquid nitrogen trapped mercury diffusion pump, a mercury-operated gas burette, a McLeod and a Pirani gage, and a mercury manometer. It was also equipped with suitably located stopcocks for isolating various parts of the system; the vacuum ordinarily attained was between 10" and 10-6 mm of mercury. Oxygen generated by decomposing MnO2 was passed through anhydrous magnesium perchlo-rate before introducing it into the gas burette and thence to the absorption chamber.

Jan 1, 1954

By M. N. Pathasarathi, P. A. Beck, T. J. Koppenaal

EARLIER work1 indicated that in rolled and annealed copper the volume fraction of the cube-texture component may increase on continued isothermal annealing. Merlini found2 that in rolled copper the well-known increase in the amount of cube-oriented material with increasing annealing temperature3 is concurrent with grain growth, which takes place after recrystallization is complete. It was found that both in copper2 and in aluminum4 the texture resulting from primary recrystallization, even if this is followed by some grain growth, may in general comprise, in addition to the cube-texture component, four symmetrical texture components of the general type (123)[412], i.e., components not very far from the ideal orientations of the rolling texture. The volume fraction of the cube-texture component increases on further annealing at the expense of these four components.' The present work was undertaken to study quantitatively the increase in the volume fraction of the cube-texture component in the course of normal grain growth, under varying conditions. Since the grain-gr3wth behavior of A1-Mn alloys has been already investigated in some detaiL5 an A1 + 0.8 pct Mn alloy was chosen for this work, in which the extent of normal grain growth can be effectively controlled by the inhibiting effect of a dispersed second phase. EXPERIMENTAL PROCEDURE High-purity aluminum of the following composition was used: A1 99.997 pct, Cu 0.0004 pct, Fe 0.0005 pct, and Si 0.001 pct. A high-purity A1-Mn master alloy was prepared by dehydrating manganese chloride at 500°C and reacting it with molten high-purity aluminum at 750°C in a graphite crucible.5 The Mn metal reduced from the salt by the molten aluminum goes into solution in the latter. The master alloy? containing 13 pct Mn, was solidified under conditions suitable for minimizing segregation. An ingot of the final alloy, to be used in the experiments, was per pared by melting high-purity aluminum and the necessary amount of master alloy in a graphite crucible, and by pouring the molten alloy into a graphite mold preheated to 700°C through a box containing graphite baffles designed to intercept most of the aluminum oxide films floating in the melt. The melt was then solidified by placing the mold on a water-cooled copper plate and by keeping the top of the mold hot, in order to minimize piping. The 6 1/2 in. long, 11/4-in.diam ingot consisted largely of a single crystal. Chemical analysis showed that there was little segregation from the bottom (0.83 pct Mn) to the top (0.81 pct Mn). Spectrographic analysis of the ingot showed that the impurity content remained essentially the same as that of the aluminum used. The ingot was processed so as to obtain a uniformly small grain size. without banding. The ini-tial steps of rolling in the form of a flat bar and of annealing, down through a thickness of 0.4 in., are shown in Table I. At this point the bar was cut into four sections, each approximately 3 in. long, which were processed separately as shown in Table If. The table also gives the penultimate grain sizes obtained in each section by annealing prior to the final rolling of 90 pct RA. During the final rolling the strips were reversed end to end between passes. Annealing treatments were given in a salt pot furnace, with the temperature controlled to 1°C. All annealing of section "6s" was carried out above the solvus point to avoid the formation of second-phase precipitate. The penultimate annealing was sufficiently short to give a relatively fine grain size in spite of the high temperature. Section "6L" was processed in a similar manner, except that the penultimate annealing was much longer, so as to allow considerable grain growth. Section "4" was given the two final

Jan 1, 1961