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By B. Fazan, O. D. Sherby, J. E. Dorn

McLean's technique was employed to determine the effect of temperature on the contribution of grain boundary shearing to the total creep strain in pure aluminum over the range of 610° to 747°K. The contribution of grain boundary shearing at the same stress was found to depend upon a temperature-compensated time, where the activation energy AH was practically identical with that for total high temperature creep. SEVERAL outstanding investigations by McLeanl-' have demonstrated that the total creep strain in polycrystalline aluminum at 473°K arises from microscopically detectable slip, subgrain tilting, and grain boundary shearing. Whereas microscopically detectable slip arises from dislocations that move out of the grains, subgrain tilting is due to entrapment of dislocations of like sign in subgrain bound-arles. Consequently, creep in polycrystalline aggregates appears to be the resultant of two mechanisms, namely, migration of dislocations and grain boundary shearing. This suggests that an appropriate law for creep should contain two additive terms ?1 = ?d + ?yb where the total creep strain, ?1, depends on the sums of the creep strains arising from motion of dislocations, ?d, and from grain boundary shearing, ?yb. But extensive investigations5 over wide ranges of alloys, grain sizes, temperatures, and stresses have shown that the total creep strain is quite accurately dependent on the single term functional relationship ?1 = f (?), s = constant where s is the stress (constant),* ? = te-?H/RT, t is the time under stress, AH is the activation energy, R is gas constant, and T is absolute temperature. Since Eq. 2 was found to be valid over those ranges where appreciable grain boundary shearing is observed, it appears probable that the activation energy for grain boundary shearing might be identical with the activation energy for migration of dislocations. Thus, under a given stress, it could be thought that where fd and fgb represent the appropriate functions for each mechanism of creep. The primary objective of this investigation was to obtain a direct check on the accuracy of this hypothesis. Experimental Procedure and Results Rolled aluminum sheet (99.987 pct Al), 0.100 in. thick, was used in this investigation. Creep specimens having a 0.25 in. wide, 3 in. long gage section were so machined that their axes were in the rolling direction. All specimens were annealed for 9 hr at 894°K before testing to produce a mean grain diameter of about 0.1 in. One face of each specimen was polished electrolytically in 10 pct HBF4. In order to permit accurate measurements of grain boundary shearing, the polished surface was lightly scribed with a ruling machine accurate to ±0.0001 in. to give a uniform grid of lines which were 0.01 in. apart. Although it was thought that surface working might modify the creep behavior in the vicinity of the scribed grid lines, this technique nonetheless was employed because such local differences in creep properties should not modify seriously the fractions of the total creep strain due to grain boundary shearing or to migration of dislocations. All creep tests were conducted under constant load with an initial stress of 250 psi. The specimen tem-

Jan 1, 1955

By L. Douglass Anderson

Fox some years past the annual reviews of the metallurgy of lead have almost uniformly stated that there have been no great changes, such as there were, being more particularly noticeable in the refinement of details. While this is quite true, nevertheless these changes in details are gradually bringing about a condition that, taken as a whole, constitutes a considerable advance in the art. Local circumstances have often -compelled metallurgists to adopt certain peculiarities of practice which -upon trial have been found advantageously applicable to more than the restricted district f origin. This paper will deal ' with some of the more novel features developed in recent years at the United States smelter, Midvale, Utah, particularly with reference to the influence of the bag house. The plant is equipped with six blast furnaces, 48 by 160 in., mechanically fed; four Wedge furnaces for roasting matte and sulphide ores; four Dwight-Lloyd sintering machines; 20 converter boxes for blast roasting; storage bins for ore, fuel, and fluxes; "oxide" and "sulphide" sampling mills; bag house taking all the gases of the plant; arsenic plant for treating the dust gathered there; laboratory, shops, etc. The most marked feature of the plant is its complete bag-house system. Of the many schemes thus far tried for preventing damage to surrounding agricultural interests the writer is aware of none as yet quite as efficient as the bag house. A common remark of visitors upon approaching the plant and viewing the clear stacks is that it appears to be shut down, whereas once inside all the evidences of industry are found.

Jan 7, 1914

By J. B. Cheatham, R. B. Paslay

Rock stresses and steady-state flow rates induced by the pressure gradient associated with the flow of formation fluid into a borehole have been analytically determined for a permeable, elastic material saturated with an incompressible fluid. In this analysis, the material properties and loading are considered to be symmetric about the axis of the borehole and independent of axial position. For Case I the material is assumed to have uniform permeability in the radial direction, whereas for Case 11 the permeability is assumed to have been reduced in a localized region adjacent to the hole by either normal well completion and production operations or deliberate plugging during air drilling. Results of a numerical example indicate that, in the absence of plugging, the rock shear strength must be approximately two-thirds the formation fluid pressure in order to prevent rock failure. The required rock strength is high for small radial zones of plugging and decreases as the region of reduced permeability becomes larger; however, a depth of plugging can be reached beyond which there is no real gain in strength, although the flow rate can be further reduced. INTRODUCTION During normal production of oil from a well, it is often desirable to increase the production rate of the formation fluid by increasing the pressure gradient through the formation adjacent to the borehole. Depending upon the magnitude of this pressure gradient and strength of the rock material, this production-rate increase can cause sloughing of the hole wall. In many cases, the production - rate increase can result in excessive sand production, increased wear of production equipment, lost production time and expensive workover jobs. In addition, the phenomenon of increased rock bit penetration rate with the use of a gaseous instead of a liquid drilling fluid has been observed in oilfield drilling operations and experimentally demonstrated by various investigators for several years. The improvement obtained by employing this technique can be quite significant and offers apromising method for reducing drilling costs. However, air drilling is currently limited to geographical locations where high-capacity water-bearing formations are not encountered. This limitation has prevented widespread adoption of air-drilling techniques, because the water influx into the borehole interferes with efficient removal of the drilling cuttings and usually results in a condition such that the bit becomes "balled-up" or stuck in the hole. In an attempt to remove the water - intrusion limitation from air drilling, various chemical and mechanical water shut-off methods have been proposed. Goodwin and Teplitzl suggested one such proposal whereby the permeability of the water-bearing rock structure was reduced in the vicinity of the borehole. Although the development of a shut-off method based upon this approach would certainly be welcomed by the oil industry, it is conceivable that, under certain conditions of the pressure gradient, strength of the rock material and depth of the modified permeability zone, a stress field can be created that will result in an unstable hole. As part of their study, an analytical solution is given for stresses in an idealized model of a hole and the surrounding rock material. The purpose of the present study is to extend the analysis of Goodwin and Teplitz to gain more insight into the details and consequences of excessive production rates and formation water shut-off. In particular, simplified models of these problems have been analytically examined, which makes possible the evaluation of the type of stress fields that can be anticipated as a result of these production and drilling practices. Both problems solved concern the determination of the steady-state volume flow rate of the formation fluid and the resulting steady-state stress and displacement distribution in a hollow, cylindrical configuration. The cylinder of Case I, corresponding to the production-rate problem, consists of a material with a constant permeability from the inside surface to the outside surface; the cylinder of Case 11, corresponding to the water shut-off problem, consists of a material with a constant permeability from the inside surface to an intermediate concentric cylindrical surface and a second constant permeability from the intermediate surface to the outside surface-

By L. Douglass Anderson

Fox some years past the annual reviews of the metallurgy of lead have almost uniformly stated that there have been no great changes, such as there were, being more particularly noticeable in the refinement of details. While this is quite true, nevertheless these changes in details are gradually bringing about a condition that, taken as a whole, constitutes a considerable advance in the art. Local circumstances have often -compelled metallurgists to adopt certain peculiarities of practice which -upon trial have been found advantageously applicable to more than the restricted district of origin. This paper will deal with some of the more novel features developed in recent years at the United States smelter, Midvale, Utah, particularly with reference to the influence of the bag house. The plant is equipped with six blast furnaces, 48 by 160 in., mechanically fed; four Wedge furnaces for roasting matte and sulphide ores; four Dwight-Lloyd sintering machines; 20 converter boxes for blast roasting; storage bins for ore, fuel, and fluxes; "oxide" and "sulphide" sampling mills; bag house taking all the gases of the plant; arsenic plant for treating the dust gathered there; laboratory, shops, etc. The most marked feature of the plant is its complete bag-house system. Of the many schemes thus far tried for preventing damage to surrounding agricultural interests the writer is aware of none as yet quite as efficient as the bag house. A common remark of visitors upon approaching the plant and viewing the clear stacks is that it appears to be shut down, whereas once inside all the evidences of industry are found.

Jan 7, 1914

Jan 1, 1971

By Robert E. Tally

Underground fires have been common in the mines of the United Verde Copper Co. for the past 22 years. The first fire started in the 300 Hampton stope in the fall of 1894, following a cave in that orebody. The soft and highly pyritic nature of the ores is responsible for most of these fires. Since ore characteristics, methods of mining and ventilation, have an important influence on mine fires, they will be described in this paper. Orebodies The ores are mostly chalcopyrite except on the upper levels where considerable chalcocite, black oxides and other secondary minerals occur. The orebodies are in the form of lenses and vary in size. Some are small, while others are several hundred feet in length by a hundred or more feet in width. These orebodies extend, in some cases, from the surface to the lowest levels of the mine and usually at a steep angle of inclination. There are three different classes of ores, classified in accordance with the gangue rock. The copper in all cases, except as above specified, is in the form of chalcopyrite. The largest and most important of these reserves are in a pyrite gangue. Next in order of importance are the schist ores and lastly the quartz porphyries. The pyrite, locally termed iron ores, average from 30 to 42 per cent. sulphur. The schist and quartz porphyries vary from 3 to 25 per cent. sulphur. Mining Methods All the orebodies were worked by the overhand square-set method of mining prior to 1908; since then the cut-and-fill, shrinkage and mill-hole systems have been largely employed. But 15 per cent. of the total tonnage now extracted is from timbered stopes. Most of this is from the upper levels where the ore is soft, heavy and more or less broken to the surface. Large reserves of these ores are being conserved for more efficient methods of mining.

Jan 1, 1917

By Robert Isaac Williams

The Questa mine is located in northern New Mexico on the western flank of the Sangre de Cristo Mountains about 75 miles north of Santa Fe and ranges in elevation from 6,800 to 10,000 ft. GEOLOGY The rocks of the area are Precambrian metamorphic rocks covered by Tertiary extrusive andesites and rhyolites and intruded by Tertiary granitic rocks. These Tertiary intrusives are localized in an east-west belt about 20 miles long and 2 miles wide, extending from Questa to Red River. The Questa orebody is associated with a north-trending aplite intrusive about 3/4 mile wide and 1 3/4 miles long. In the area of mineralization, the metasomatism of aplite has produced a mottled porphyritic rock. This hybrid rock has caused much of the controversy about the Questa mine intrusive. The orebody is essentially monomineralic and consists of numerous closely spaced molybdenite veins varying in thickness from ' 'paint" to 3 in. and occurring in both the andesites and the intrusive. In the intrusive the veins are often siliceous. Common alteration minerals associated with the molybdenite ore vary with the original composition of the rock. The alteration of the aplite has produced phenocrysts of orthoclase, albite, oligoclase and biotite; veins of quartz, orthoclase, and biotite; and graphic myrmekitic intergrowths of feldspars and quartz. In many places near the contact, the andesite is indistinguishable from the metasomatized aplite. The dominant alteration in andesite, however, is the development of fine-grained biotite with apatite, rutile, and sphene.

Jan 1, 1969

By Robert Linton

The Sierra Consolidated Mines Co., organized in 1909, owns, together with other holdings, practically all of the productive mineral area in the Ocampo district. Lying within this area are 15 mines, large and small, that hid previously been worked and appear to have yielded, since the discovery of the camp, about 100 years ago, bullion of a total value of over $50,000,000. The deepest mine, the Santa Juliana, had been worked to 1,100 ft. below the outcrop. The reopening of the mines involved, first, extensive and thorough development to open up the known ore shoots at greater depth and explore the ledges for additional shoots, and, second, a revision of existing equipment and methods, so as to increase output and reduce cost of production. This paper will give some account of the metallurgical treatment and a description of the new mill to be built at El Salto. The Ore The ore is practically all argentite, Ag2S, with some associated gold, and carried in a siliceous gangue. The typical ledge matter is an ande-sitic breccia cemented with quartz, or quartz stockwork in andesite.l The proportion by weight of silver to gold averages about 60 to 1. The silver sulphides occur ordinarily in rather fine. dissemination, sometimes not being easily discernible with the naked eye, even in ores of very good grade. The ledges also contain considerable pyrites, which as a rule is barren. "Bronce" is the local term applied to such barren pyrites, and "Pasta" to such as carries values.

Jan 1, 1915

By Seymour Fiekowsky, Alvin Kaufman

Taxes are compulsory charges levied by a government for its support. They are usually paid to support the general services provided by government rather than special services (such as safety inspection). The latter are normally supported by user charges often called license fees. Taxes are used by national governments not only to raise money but also as a part of fiscal policy. As such, taxes are used to stimulate or deflate the economy, as an incentive to save or invest, as a means of allocating national resources, and as a means of redistributing income. In our discussion, we will deal only with those facets of the subject that relate specifically to the mineral industry. In doing so we will deal with taxes levied on all industry in a generalized way and only insofar as it affects our industry, but at some length on those portions of the tax system related directly to the mineral industry. It is not our intent to provide a "cookbook" for computing taxes, but rather to present some of the policy issues that bedevil those who must develop our tax policies. MINERAL TAXES The mineral industry is subject to the full range of taxes levied by governments. These include taxes on income, property, and sales, as well as excise and severance taxes. The latter are somewhat similar to a royalty in , that such taxes are levied either ad valorem or per unit of output. Severance taxes most commonly are charged to oil and gas output, although coal, salt, sulfur, and iron ore production also have been taxed in this manner. The major governmental advantage of the severance tax is the administrative ease of collection. On the other hand, it poses an addition to cost independent of profitability. As a consequence, the severance tax can cause premature abandonment if mineral product prices do not rise sufficiently to cover it. Such a rise may not occur if differential tax rates are levied by the various states. Property taxes normally are levied on all property owners, including mineral owners. The major difficulties in this kind of tax, in so far as mining is concerned, are erratic valuation coupled to the inherent problems involved in assessing a property where the extent and richness is chiefly unknown. The impact of these taxes, including state income taxes, is reduced somewhat, as they are usually deductible from gross income as a business expense with a consequent lowering of national income taxes. The net cost of severance, property, sales, and state or local

Jan 1, 1976

By H. Leslie Bullock

From aluminum to zirconium, the quantitative preponderance of quartz as a gangue material is well recognized. lf this material is to be efficiently removed, its variations must be understood. Variations with temperature are especially important. Too little attention has been given to the thermal polarization of quartz. Under closely controlled conditions, electrostatic upgrading is very reliable. For efficient separation, contact charges must be fostered and charges due to radiation, surface coatings, or thermal polarization avoided. This paper lists thermal transition points of quartz and shows their effect on actual separations. Simple separation tests with all factors except temperature held constant are recommended for determining transition points. With silica making up more than 27% of the earth's crust, its oxides comprising more than 59% of all igneous rocks, and quartz accounting for most of the main free oxides, the mining engineer is in constant contact with quartz, which may occur as a valuable mineral to be purified or, far more frequently, as a gangue material to be removed as completely and economically as possible. As a means of effecting such purification or removal, dry beneficiation is becoming more and more desirable owing to local water scarcities, wet waste disposal problems, or freezing conditions. One method that has been gaining particularly rapid acceptance is electrostatic beneficiation, or the separation of dry free-flowing materials by means of opposite surface charges, differences in potential, or differences in conductivity. Electrostatic beneficiation dates back to the 1870's, but only in recent years have newly developed methods and apparatus and a growing knowledge of solid-state physics widened the field for its economical application. Because the term "electrostatic beneficiation" has been rather loosely used in the literature, it has come to include both electrostatic and electrodynamic procedures. Attracting type separators, however, in which oper- ation is based on differences of surface charge or potential, are truly electrostatic, because the separation occurs in a substantially static field set up between oppositely charged surfaces. Separations with this type of equipment may occur at potentials as low as 1000 v and seldom require potentials as high as 30,000 v. In the new contact charge dielectric separators1 the variation in charge is produced by continuous contact and separation of the particles in the moving feed stream and these charges are fostered by the use of non-conducting support and feed surfaces and by handling the feed in the form of streams of appreciable depth. This favors uniformity of feed and allows higher production rates. The distinctive surface charge differences are set up on the separation of the particles according to Coehn's Law,2 which states that equal and opposite charges are generated on the separation of any two materials in contact and that the substance having the highest dielectric constant will be positively charged. The basic contact charge concept is reliable, but all electrical charges are transient and modified by the electrical conditions of the surroundings. Pyro-electric, photoelectric and radiant effects may modify or totally destroy the contact charges necessary for efficient separation, or contact with conducting surfaces may neutralize them. Such hostile conditions must be carefully guarded against, since they have led to many costly failures in the past. The most consistent difference in surface charges to insure good separation is produced by repeated uniform contact and separation of particles in the moving stream. The thickness of the feed stream possible with this method reduces the effect of contact with the supporting surfaces, but as some contact is inevitable, the best results may be assured by having the dielectric constants of the supporting surfaces between the dielectric constants of the substances to be separated. In general, the hard smooth surface of quartz makes it an ideal substance for electrostatic separation from most minerals. For instance, with calcite, starting with a feed containing 1.9% acid insolubles, one can produce a concentrate containing 0.30% acid insolubles with a tailings containing 21.7% acid insolubles and a yield of 92.8%. The color can be held at 92 or above and the tint at 1.7 or lower. Working with specularite iron ore, laboratory work has given a concentrate of 68.8% Fe., with an iron unit recovery of 96.7%. Excellent results are also in pros-

Jan 1, 1969

By F. F. Aplan

Mineral processing engineers have recorded an- other year of active research and development work. Most gratifying was the broadly based attendance at the Mineral Processing Fundamental (formerly Basic Science) Committee sessions at the 1968 Annual Meeting of the AIME. Because of the availability of good papers, the active discussion and the growing attendance, sessions have grown from one to three at the annual meeting. Prof. M. C. Fuerstenau of the University of Utah will chair the Mineral Processing Fundamentals Committee for the next two years and we may thus be assured of continued active leadership. The name change from "Basic Science Committee" to the more descriptive "Mineral Processing Fundamentals Committee" approved by the MBD executive council is a welcome improvement. Our profession continues to attract the interest and cooperation of those in other professional groups. The 1968 Engineering Foundation Particulate Matter Conference, under the chairmanship of John Karpinski of Bethlehem Steel, was devoted exclusively to comminution this year. It attracted conferees from five continents and served as a particularly stimulating source of interchange of knowledge from many technical fields. Next year's conference will be under the chairmanship of Professor L,. G. Austin of The Pennsylvania State University. This conference plus the Symposium on Wettability and Flotation to be held at the annual American Chemical Society meeting in Minneapolis in April indicates the success achieved in the inter-disciplinary approach to problems. Other evidence of this spirit of professional cooperation is the forth- coming book on Size Reduction edited by D. W. Fuerstenau. This is the outgrowth of an AIChE symposium on size reduction held in 1965.

Jan 2, 1969

By Robert M. Dreyer

Although lateritic ore deposits are relatively flat-lying, surficial ore bodies, the evaluation of lateritic bauxite and nickel deposits is among the most difficult problems confronting an economic geologist. Laterite is a soil formed under tropical conditions resulting in the concentration, within the soil zone, of certain trivalent metals - principally iron and aluminum, but also, locally, nickel and manganese. The soil zone is divided into two parts: (a) the true soil or lateritic zone and (b) the zone of partially altered bed rock or saprolite. Whereas bauxite generally is confined to the lateritic zone, some nickel deposits occur in both the laterite and saprolite zones. The evaluation of bauxite and lateritic nickel deposits thus has both similarities and differences. These ores have been formed by supergene, soil-forming solutions moving downward through zones of widely varying permeability within the weathering rock. Because the permeability varies widely, both vertically and laterally. the extent of weathering may vary greatly within short distances. Because the weathering process varies widely, the degree of metal concentration may also vary widely. It is not at all uncommon for a laterite to change, within a few centimeters, from a virtually valueless rock to a high grade ore. Moreover, the depth of weathering, and hence the depth and form of the ore profile, vary greatly. Obviously, for this type of deposit, a few grab samples or a few drill holes are virtually worthless. The evaluation of such a deposit requires a sophisticated statistical study based on thousands of carefully selected samples. As a rule of thumb, the cost of evaluating a large bauxite or lateritic nickel deposit will be about one cent per ton of ore in the ground. Thus, the cost of evaluating a several hundred million ton deposit may be considerable. The following factors must be considered during the evaluation: Type of Sampling: The best and most reliable samples for the evaluation of lateritic ores are taken along large, vertical channels in hand-dug pits. Where labor costs are high, some form of drilling may be used in place of pitting, but it is always wise to choose a drilling procedure after checking drilling results against a series of pit channel samples. The drilling may not reproduce exactly the results from pit channel samples, but it may be possible to derive a constant correction factor. If the physical character of the laterite varies within the deposit, it may, of course, be necessary to change the type of drilling, the correction factor or both. In some areas, it has been found empirically that augers, chum drills, vacuum drills, rotary drills, or core drills yield satisfactory results. The problem is to find which drilling technique gives results most similar to channel samples through the heterogeneous sequence characterizing the laterite in a given area. In lateritic nickel deposits, the drilling characteristics of the lateritic and saprolitic portions of the deposit are very different. Within the saprolite, the major nickel values are commonly found in weathered zones within less altered boulders - a type of occurrence which makes sampling very difficult.

Jan 1, 1979

By K. E. Brown, A. R. Hagedorn

Continuous, two phase flow tests have been conducted during which four liquids of widely differing viscosities were produced by means of air-lift through 1%-in. tubing in a 1,500-ft. experimental well. The purpose of these tests was to determine the effect of liquid viscosity on two-phase flowing pressure gradients. The experimental test well was equipped with two gas-lift valves and four Maihak electronic pressure transmitters as well as instruments to accurately measure the liquid production, air injection rate, temperatures, and surface pressures. The tests were conducted for liquid flow rates ranging from 30 to 1,680 BID at gas-liquid ratios from 0 to 3,-270 scf/bbl. From these data, accurate pressure-depth traverses have been constructed for a wide range of test conditions. As a result of these tests, it is concluded that viscous effects are negligible for liquid viscosities less than 12 cp, but must be taken into account when the liquid viscosity is greater than this value. A correlation based on the method proposed by Poettmann and Carpenter and extended by Fan-cher and Brown has been developed for 1¼-in. tubing, which accounts for the effects of liquid viscosity where these effects are important. INTRODUCTION Numerous attempts have been made to determine the effect of viscosity in two-phase vertical flow. Previous attempts have all utilized laboratory experimeneal models of relatively short length. One of the initial investigators of viscous effects was Uren1 with later work being done by Moore et al.2,3 and more recently by Ros.4 However, the present investigation represents the fist attempt to study the influence of liquid viscosity on the pressure gradients occurring in two-phase vertical flow through a 1¼-in., 1,500 ft vertical tube. The approach of some authors has been to assume that all vertical two-phase flow occurs in a highly turbulent manner with the result that viscous effects are negligible. This has been a logical approach since most practical oil-well flow problems have liquid flow rates and gas-liquid ratios of such magnitudes that both phases will be in turbulent flow. It has also been noted, however, that in cases where this assumption has been made, serious discrepancies occur when the resulting correlation is applied to low production wells or wells producing very viscous crudes. Both conditions suggest that perhaps viscous effects may be the cause of these discrepancies. In the first case, the increased energy losses may be due to increased slippage between the gas and liquid phases as the liquid viscosity increases. This is contrary to what one might expect from Stokes law of friction,' but the same observations were made by ROS4 who attributed this behavior to the velocity distribution in the liquid as affected by the presence of the pipe wall. In the second case, the increased energy losses may be due to increased friction within the liquid itself as a result of the higher viscosities. The problem of determining the li- quid viscosity at which viscous effects becomes significant is a difficult one. Ros4 has indicated that liquid viscosity has no noticeable effect on the pressure gradient so long as it remains less than 6 cstk. Our tests have shown that viscous effects are practically negligible for liquid viscosities less than approximately 12 cp. Actually there is no single viscosity at which these effects become important. These effects are not only a function of the viscosities of the liquids and of the gas but are also a function of the velocities of the two phases. The velocities in turn are a function of the in situ gas-liquid ratio and liquid flow rate. Furthermore, the role of fluid viscosities in either slippage or friction losses will depend on the mechanism of flow of the gas and liquid, i.e., whether the flow is annular. as a mist, or as bubbles of gas through the liquid. These mechanisms are also a function of the in situ gas-liquid ratios and the flow rates. It would thus seem that the best one could hope for is to determine a transition region wherein the viscous effects may become significant for gas-liquid ratios and liquid production rates normally encountered in the field. The viscous effects might then be neglected for liquid viscosities less than those in the transition region but would have to be taken into account when higher viscosities are encountered. There are numerous instances where crude oils of high viscosity must be produced. The purpose of this study has been to evaluate the effects of liquid viscosities on twephase vertical flow by producing four liquids of widely differing viscosities through a 1 % -in. tube by means of air-lift. The approach used in this study was as follows:

Jan 1, 1965

By F. D. George, M. J. Salkind

Al3Ni whisker-reinforced aluminum was found to exhibit good Charpy impact toughness and little notch sensitivity even though its room-temperature tensile elongation parallel to the whiskers is only 2 pct. This impact behavior was maintained d liquid nitrogen temperature (-196"C). It is postulated that this behavior is due primarily to the presence of the continuous aluminum matrix which provides sufficient 10calized ductility in the vicinity of the crack tip to absorb considerable energy from the advancing crack. The impact behavior of Al-Alni was found to be quite anisotropic. Of six orientations studied, the transverse orientation having the notch normal to the whisker axis was found to exhibit the lowest impact energy, whereas the transverse orientation having the notch parallel to the whisker axis was found to exhibit the highest impact energy. A significant differnce was noted between the impact behavior of material containing needlelike whiskers and that containing bladelike whiskers. Only two of the six orientations studied exhibited complete fracture for the material containing needlelike whiskers. On the other had, most of the specimens containing bladelike whiskers exhibited complete fracture. It was postulated that the bladelike whiskers block transverse flow, thus reducing the amount of plastic deformation ahead of the crack tip. One of the more significant advantages of composite materials is the prospect of combining high strength with toughness. In general, toughness is associated with materials which exhibit considerable ductility and can deform plastically in the presence of a stress concentration. Very strong materials which resist plastic deformation generally exhibit low toughness. At first glance, then, it would appear as though strength and toughness are mutually incompatible so that useful engineering materials would have to be a compromise between the two. One approach to the problem of combining the high intrinsic strength of ceramics with the toughness of metals was to mix them together to form a cermet. Unfortunately, the toughness of cermets was found to be rather disappointing. Whisker reinforcement of metals, however, appears to be a more promising approach. It has been demonstrated that whisker-reinforced metals produced by unidirectional solidification exhibit enhanced strength due to the presence of high strength nonmetallic whiskers. The total strain capacity of these composites in the direction of fiber alignment is limited to that of the fibers, the matrix being unable to carry the load once the fibers have failed. A characteristic, then, of whisker composites is low ductility in the direction of whisker alignment, on the order of a few percent elongation. This low elongation, which is usually associated with brittle behavior, should not be taken as an indication of low toughness. Such a material can exhibit significant ductility in directions other than parallel to the fibers7 and can therefore possess significant intrinsic toughness. Toughness in a fiber-reinforced metal is derived from several mechanisms. The first is due to the toughness of the matrix itself. A continuous ductile metal matrix can act as an effective crack arrest medium by undergoing localized plastic deformation. Cracks initiated from the surface of the composite or from a brittle fiber failure must travel through the matrix before reaching another brittle phase particle. A second crack arrest mechanism peculiar to fiber composites is due to the fact that, as a crack travels through the matrix and approaches a fiber, the plastic deformation ahead of the crack tip will result in loading of the fiber. This causes the matrix shear strength in the plastic zone to be apparently higher, thus extracting more energy from the crack and diverting the crack at an angle to the original direction of propagation. A third crack arrest mechanism occurs in fiber composites which exhibit a weak bond between fiber and matrix. The idea was proposed by Cook and Gordons that if a crack propagating transversely in a fiber composite were made to turn and run along the fibers by decohesion of the fiber-matrix bond, then toughness would be imparted by the blunting of the crack tip and the creation of new surfaces. The last mechanism, interfacial decohesion, is commonly noted in naturally occurring fiber composites such as wood, bone, and bamboo, and has been observed in man-made composites such as glass fiber-reinforced resins,g silica fiber-reinforced aluminum," laminated steel," and tungsten and silica fiber-reinforced electroplated copper.'' The first mechanism, crack arrest by plastic deformation in the matrix, has been noted in tungsten wire reinforced cast copper." The purpose of this investigation was to quantitatively assess the toughness of a whisker-reinforced metal as a function of orientation. Previous investigation considered only cracks propagating nominally perpendicular to the reinforcement. In this investigation, crack propagation in three mutually perpendicular directions as well as three intermediate orientations was investigated. The system chosen for study was the unidirectionally solidified A1-A13Ni eu-tectic alloy which has a microstructure consisting of 10 pct by volume of A13Ni whiskers in a matrix of aluminum This material exhibits two different kinds of whisker morphology, depending upon the rate at which it is solidified.' At low rates of solidification (less than 2 cm per hr) the whiskers are bladelike, whereas at higher rates of solidification they are

Jan 1, 1969

By C. H. Mathewson, A. U. Seybolt

As is well known, many questions affecting the properties and uses of a metal cannot be answered without careful consideration of the state of purity realized in the various operations of preparation, refining, or special treatment that have brought the product to its final state. The occurrellce of an impurity in minute quantity offers no guarantee that its effect will be inconsiderable because dissolved substances often modify the properties of a metal quite out of proportion to their concentration. In such cases the determination of solid solubility must be accepted as a problem of considerable difficulty, requiring the use of especially purified materials and methods not ordinarily used in the metallurgical laboratory. This aspect of the equilibrium between metals and their oxides is especially important and a search for fundamental data reveals little except conflicting opinion even concerning the systems of common occurrence and interest. Rhines and Mathewson1 in 1934 studied the solubility of oxygen in solid copper by annealing to equilibrium in air and gave reasons for the failure of other methods, notably the ordinary procedure of heat-treatment followed by microscopic examination, to yield reliable results. In this paper, a similar study has been made of the solubility of oxygen in cobalt. The simple theory of this method is outlined below. Conditions of Equilibrium between a Metal and Dissolved Oxide at Different Temperatures and Pressures The general conditions of equilibrium in any system are conveniently summarized in a projection of the triple curves of the P, T, X space

Jan 1, 1935

By A. U. Seybolt, C. H. Mathewson

As is well known, many questions affecting the properties and uses of a metal cannot be answered without careful consideration of the state of purity realized in the various operations of preparation, refining, or special treatment that have brought the product to its final state. The occurrellce of an impurity in minute quantity offers no guarantee that its effect will be inconsiderable because dissolved substances often modify the properties of a metal quite out of proportion to their concentration. In such cases the determination of solid solubility must be accepted as a problem of considerable difficulty, requiring the use of especially purified materials and methods not ordinarily used in the metallurgical laboratory. This aspect of the equilibrium between metals and their oxides is especially important and a search for fundamental data reveals little except conflicting opinion even concerning the systems of common occurrence and interest. Rhines and Mathewson1 in 1934 studied the solubility of oxygen in solid copper by annealing to equilibrium in air and gave reasons for the failure of other methods, notably the ordinary procedure of heat-treatment followed by microscopic examination, to yield reliable results. In this paper, a similar study has been made of the solubility of oxygen in cobalt. The simple theory of this method is outlined below. Conditions of Equilibrium between a Metal and Dissolved Oxide at Different Temperatures and Pressures The general conditions of equilibrium in any system are conveniently summarized in a projection of the triple curves of the P, T, X space

Jan 1, 1935

By F. W. Schremp, J. W. Chittum, T. S. Arczynski

This paper describes a laboratory study of causes of external casing corrosion and the test work that led to the use of oxygen scavengers to prevent this attack. External casing failures are classified as water-line, casing-casing, collar and body failures. A corrosion mechanism based on principles of differential oxygen availability is developed that is consistent with facts known about each kind of failure. The field use of oxygen scavengers is depicted as a direct result of the laboratory study. A part of the paper is devoted to reporting on the field use of hydra-zine to control external casing corrosion. Results of field measurements made over a period of several years are presented as evidence of the efectiveness of the hydrazine treatment. The first conclusion reached is that the use of hydrazine materially reduces the cathodic protection requirements for treated wells. This result is interpreted to mean that a reduction is taking place in the amount of corrosion on the casing. Results indicate also that hydrazine shows its greatest usefulness within the first 12 to 18 months after a well is completed when pitting corrosion is likely to be most active. INTRODUCTION According to surveys sponsored by the National Association of Corrosion Engineers,' the cost of repairing casing leaks caused by external corrosion may exceed $4 million per year. In addition, well damage and lost production resulting from casing leaks probably costs the petroleum industry an additional $5 to $6 million per year. Concern about the cost of external casing corrosion led to an extensive laboratory study of factors causing this external corrosion and to the development of a new approach to its prevention. This paper presents a discussion of various causes of external casing corrosion, details of laboratory studies and the results of the field use of an oxygen scavenger in well cementing fluids to prevent the external corrosion of oil-string casing. Measurements on test wells over a period of several years show that cathodic-protection current requirements are greatly reduced when hydrazine is used in cementing mud. Reduction of current requirements can be interpreted to mean that removal of oxygen by hydrazine has greatly suppressed corrosion cells on the external surface of the casing and thereby, has reduced corrosion. To date, hydrazine has been used by the Standard Oil Co. of California in more than 200 well completions. KINDS OF CASING FAILURES A survey of a large number of casing leaks disclosed four types of external casing failures — water-line, casing-casing, collar and body failures. These types are identified largely by their location on the casing. Water-line failures are found just below the surface of water or mud in the casing annulus. Casing-casing failures occur on the oil string just below the shoe of the surface string. Collar failures are found in the threaded ends of casing joints where they are screwed into casing collars. Body failures may occur at any point on the body of a casing joint. Ex- amples of each kind of failure have some of the general characteristics that are shown in Fig. 1. Water-line failures usually result in the circumferential severance of an oil-string casing. The corrosive action causing a water-line failure usually is sharply defined and is limited to a short length of the casing. Casing-casing failures usually are accompanied by pitting corrosion distributed around the oil-string casing for distances up to 100-ft below the shoe of the surface string. Casing-casing failures may also sever the casing. Collar failures seem to start on the first thread at the bottom of recesses between collar and casing joint. Corrosion proceeds across the threads by what appears to be a normal pitting mechanism. Both casing and collar are severely attacked. Body failures are the result of highly localized pitting at any point on a casing wall. Besides the pit that perforates a casing, a large number of other pits usually are found along one side of the casing joint. The pits occasionally are filled with corrosion products consisting largely of oxides and sulfides.' Frequently, the mill scale is largely intact on the rest of the casing. Examination of a casing failure does not always reveal the cause of the failure. Frequently, the necessary details are destroyed when the failure occurs. For example, formation water flowing through a perforation at high velocity may enlarge the hole and destroy any remaining evidence of the cause of the failure. One way to obtain undistorted information about a failure is to study the nature of other pits on the casing in the vicinity of the failure. A study of such pits frequently suggests that they are characteristic of an attack resulting from the differential availability of molecular oxygen.

By H. K. Work, H. B. Emerick

IN the past year the steel industry underwent an abrupt conversion from a war tempo to a highly competitive peacetime schedule. It is still too early to gain a comprehensive picture as to which of the measures in production metallurgy, that made the war effort so successful, will remain in the postwar production of steel, but many of them undoubtedly will fill an important place after the war. Considerable speculation has developed regarding the disposition of the war-born production facilities of the steel industry. These include new open-hearth and electric furnaces, as well as vast numbers of auxiliary, supplementary, and balancing units that increased and speeded up production beyond the normal capacities of existing melting furnaces and finishing mills. Although these facilities were installed primarily to help meet war requirements, consideration was also given, in planning, to their possible peacetime use. The new equipment is generally modern and efficient, and it seems reasonable to suppose that strategically located units will gradually be absorbed by various steel companies to supplement their own facilities, or to replace in kind, obsolete and inefficient equipment now ready to be scrapped. Some, however,

Jan 1, 1946

The great additional clue given to professional books by adequate alphabetical and analytical indexes has been recognized from the beginning in the publication of the Transactions of the American Institute of Mining Engineers The bust ten volumes, edited by Dr Thomas M Drown, the secretary, were provided with indexes, as well as tables of contents Moreover, he included in Vol V (published in 1877), a consolidated index of Vols I to V , inclusive, and, at the triune of his resignation in 1884, he had prepared a similar index of Vols I to X , inclusive, which was published in the following year The indexes of the annual volumes from Vol XI on were made much more extensive than their predecessors Casual mentions, as well as important discussions, were included, the geographical localities of mines of works alluded to in the text were added in the index, and numerous cross-references were introduced, with the purpose of making it easy for the student to discover at once what the Transactions contained, either of thorough treatment or of hints and clues to further inquiry, concerning any topic, locality, or person within their scope In order to extend the advantages of this larger scheme to the earlier volumes a consolidated index of Vols I to XV , inclusive (published in 1888), was prepared by compiling the several annual indexes and introducing additional items for those preceding Vol XI Vol XX , issued in 1892, contained a similar consolidated index for Vols XVI to XX , inclusive, in 1897, a sepal ate index-volume, covering Vols XXI to XXV, inclusive, was published, and on 1902 appeared another for Vols XXVI to XXX These four indexes, for Vols I to XV, XVI to XX, XXI to XXV , and XXVI to XXX, respectively, bound together into a book of about 950 octavo pages have constituted for the last five year s a consolidated index to the Transactions which they cover-with the single difference that the book had to be consulted four times, where a single comprehensive index would require to be consulted but once This disadvantage, however, was relatively small, compared with the great convenience of finding by four trials m one book what would otherwise call for 30 separate searches in 30 books Moreover, the possession of the one might be most useful to a student who did not possess the 30, by indicating to him what they con-

Jan 1, 1907