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By Charles M. Packer, Oleg D. Sherby, Roy H. Johnson

Originally round tensile specimens of a eutectic Zn-A1 alloy develop elliptical cross sections during superplastic deformation. This observation, coupled with a detailed study of the microstructure and preferred orieniation, suggests that crystallographic slip and continuous grain boundary migration or re-crystallization are important processes during super-plastic deformation. In spite of the extensive activity in superplasticity1-15 and the numerous explanations proposed, no single model has had universal acceptance. It has been established, however, that the general requirements for superplastic extension of two-phase alloys include an extremely fine, stabilized grain size of the order of a few microns, a temperature about equal to or greater than one-half the melting point, a critical range of strain rate, and a similarity in the mechanical strength of the major phases. The proposed models can perhaps best be characterized in terms of the important phenomena associated with them. These phenomena include: phase instability,1 diffusional creep by volume diffusion3 or grain boundary diffusion4,5 slip and continuous grain boundary migration or recrystalliza-tion,= grain boundary Sliding,7-9,13,14 and dislocation glide.'5 In this paper, experimental observations will be reported which support a model involving slip and continuous grain boundary migration or recrystalliza-tion. Specifically, a correlation will be made between this model and the development of elliptical cross sections as originally round specimens are superplas-tically deformed. For the most part, superplasticity studies have been conducted with eutectic or eutectoid alloys. Probably the most thoroughly studied material has been the monotectoid Zn-A1 alloy.1,2,6,12,13,15 No attention to the eutectic Zn-A1 alloy has previously been reported, and the results discussed in this paper represent part of a general study of the superplastic properties of this alloy. MATERIALS The alloys used in this investigation were prepared by melting appropriate quantities of 99.99+ pct A1 and 99.999 pct Zn in air, mixing, and pouring into a water- cooled stainless-steel mold. Wet-chemical analysis was conducted with each heat of alloy prepared, using the procedure of Fish and smith.16 The composition of the eutectic alloy was 95.1 wt pct Zn. Ingots about 2 in. thick were rolled to 0.4-in. plate at about 300°C with a reduction of 5 to 10 pct per pass. Specimens were machined from the plate with the tensile axis parallel to the rolling direction. The specimens were round, with 0.150-in.-diam, 1.25-in.-long gage length, and 0.25-in.-diam threaded grip sections. EXPERIMENTAL PROCEDURE Specimens were mounted inside a uniform-temperature quartz tube which was surrounded by a double elliptical radiant furnace with a 12-in.-long uniform-temperature hot zone and a low thermal capacity. The tube extended through the top and bottom of the furnace and permitted rapid quenching of the loaded specimens when quickly filled with cold water at the conclusion of the test. The quench precluded any effects on specimen microstructure from a normal, slow cool. Constant stress was applied to test specimens by suspending a load on a constant stress cam of the type described by Hopkin.17 The design of this cam permitted application of a constant stress for elongations up to 200 pct. For greater elongation, approximately constant stress conditions were maintained by systematically reducing the load manually. RESULTS As part of an investigation of the superplastic properties of the eutectic Zn-A1 alloy, evidence was obtained for the development of elliptically shaped cross sections as originally round specimens were extended. For example, after an elongation of about 100 pct, a round specimen with an initial diameter of 0.150 in. became elliptical with major and minor axis of 0.128 and 0.88 in., respectively. Photographs are presented to illustrate the ellipticity developed during superplastic deformation, Fig. 1. The specimen shown was deformed at a stress of 500 psi, at a temperature of 285°C, and a strain rate of 2.28 x 10-2 min-1. The strain-rate sensitivity exponent* was measured at *The strain-rate sensitivity exponent, m, is defined as d In o/d In c where o is the steady-state flow stress and E is the strain rate. this temperature and in the strain rate range 10"3 to 10-1 min-1 was found to be about 0.5. This value is typical of those observed with superplastic materials. The material studied exhibited negligible strain hardening during superplastic deformation, the creep rate remaining constant under constant stress and temper-

Jan 1, 1969

By Rustum Roy, E. F. Osborn

THE investigation discussed in this paper concerns phase equilibria in the alumina-silica-water system. Studies in this system are part of a re¬search project sponsored by the Geophysics Branch of the Office of Naval Research2 directed toward increasing knowledge of the stability relations of metamorphic mineral assemblages. Inasmuch as metamorphic rocks consist largely of aluminosilicate struc¬tures, many of them hydrated, the system alumina-silica-water is a logical starting point for the systematic laboratory study of metamorphic mineral systems. Although logical, this is not, however, an easy approach to the problem because of the very great difficulty of obtaining transformations among structures in response to changes in temperature, pressure, and con¬centration. Commonly equilibrium among the phases in this system is exceed¬ingly difficult to attain. New laboratory techniques are required to produce certain structural rearrangements, such as inversion of diaspore to boehmite or the transformation of alumina-silica mixtures to andalusite or kyanite. Phase equilibrium data for the alumina-silica-water system are consequently only partly complete, and only a summary progress report is presented here. Crystalline phases in the alumina-silica-water system are numerous and many are common minerals. The oxide components exist as: quartz, tridymite, cristobalite, corundum, water, and ice. Binary compounds occurring naturally are: sillimanite, andalusite, kyanite, and mullite in the alumina-silica system and gibbsite, boehmite, and diaspore in the alumina-water system. The most abundant among the ternary compounds is the composition A12O3.2SiO2.¬2H2O, existing in the four structural modifications, kaolinite, nacrite, dickite, and halloysite. The hydrated form of halloysite, A12O3.2SiO2.4H2O, is here called endellite. Pyrophyllite, A12O3.4SiO2.H2O, is the third ternary compound of natural occurrence. In addition to these minerals, two other ternary crystalline phases have been encountered in this study. The first is a structure resembling montmorillonite and corresponding perhaps to the pure aluminian end member of the beidellite series. The other has a composition approximating A12O3.2SiO2.H2O but its composition and structure are still in doubt. LABORATORY PROCEDURE In these laboratory studies, a starting material such as an alumina-silica gel or one or more of the crystalline phases is wrapped in platinum foil,

Jan 1, 1952

By J. D. Price, W. M. Bertholf

Making maximum possible use of available equipment and material, CF&I placed a high-efficiency, high-capacity washery unit in the existing buildings to gain simplified operation, reduced manpower requirements, raised efficiency, and boosted production. THE central washing plant of the Colorado Fuel & Iron Corp. was first operated in 1918 to furnish coal for two 60-oven batteries of Koppers design. Prior to that time the coke for the blast furnaces had been secured from a number of beehive operations, some with their own washeries. The original washery had four Elmore jigs, which did not do as well as had been expected. In 1923 the jigs were taken out and replaced by Deister Plat-O tables, with various changes in auxiliary equipment. In 1936 the throughput of the plant was considerably increased by the installation of vibrating filters for recovery and drying of fine coal, thereby reducing a large recirculating load of fine coal which passed through the screens of the Carpenter driers. In the late 1940's it became evident that something would have to be done to keep the washery abreast of progress at Pueblo and other washeries. Coal requirements were nearly two and one-half times the original requirements of the 120 small ovens, as additional ovens had been built in 1930, 1938, and 1945, whereas no additional coal washing capacity had been added since the 1936 modifications. Much of the equipment, moreover, had seen better days. One answer to the problem was to build a new and completely up-to-the-minute plant, with sep- arate sections for coarse, medium fine, fine, and very fine coal. On the other hand, it might be financially more profitable to place a high-efficiency, high-capacity unit in the existing buildings. The washing problem at Pueblo is not unique, but it is approached differently. There are no established specifications for coke ash and sulphur. The plant is operated on the principle that if it is more economical to wash it out than to slag it out, wash it out; otherwise, send it on to the blast furnaces. With coals at the Pueblo plant costing what they do, the benefits of washing at a low gravity are questionable. Hence the primary problem is to eliminate the high-ash components and retain all the low and medium-ash components. Sulphur is no problem at all, averaging 0.6 pct in the coke. Since a good proportion of the free impurity in the coals is as large as the coal or bone or larger, it appeared that it would be safe to go to jig washing and discontinue crushing the coal before washing, as had been the practice with the tables. This would boost the throughput. It might also decrease manpower requirements and washing costs considerably. It was assumed at the start and has been demonstrated in the first year of operation that a jig will do as well on the fines as the tables had been doing. It would not be necessary to discount any gains due to increased efficiency in washing the coarse material because of incapacity to wash the fines. By washing at —2+0 mesh it would be possible to dewater, by screening, a considerable tonnage satisfactorily, for example, at —2 + % or —2 + l/4, and then crush it in a hammer mill. The —?+20 could be dewatered in centrifugal driers and the remain-

Jan 1, 1955

By C. A. Mitke

(Butte Meeting, August, 1913.) 1. Character of Gases which Caused Helmets to Get Out of Order. DURING September, -1911, the fire area in the Lowell mine continually increased and gases resulting from the fire came through the upcast shaft. These gases contained such a large percentage of sulphur dioxide that the men were unable to go up and down on cages, and, within a comparatively short time, repairs in the shaft were found to be necessary. Since the fire was in sulphide ores and extended into certain timbered sections, the gases contained varying amounts of SO2 CO2, and perhaps, at times, CO. The temperature in the shaft was generally about 97°, and the relative humidity from 97 to 99.5 per cent. The corrosive action of the fumes became apparent when the cables had to be changed more often than usual, the heads of lag screws .in the guides of the shaft disappeared, and the cages needed frequent repairs. It also became necessary to repair two compartments of the shaft by putting in 150 ft. of new guides between the 600 and 800 levels and lag screws in nearly all the old guides from the surface to the 800 level. 2. Ordinary Methods of Testing Helmets which were Unsatisfactory. These conditions required all work to be done by men wearing oxygen helmets. The Draeger type was tried, and was used until all repairs were completed. At first the helmets were. tested for air circulation and air tightness and the injector was tested by water gauge according to the methods recommended by the Draeger Oxygen Apparatus Co. Six arrangements, covering .these different tests, are illustrated in the catalogue and circulars of the company.

Jan 7, 1913

By Strathmore R. B. Cooke

On the basis of experiments conducted on quartz using a bubble pick-up method, it was shown in an earlier paper1 that this mineral will preferentially adsorb hydrogen, calcium, or sodium ions, depending on the relative concentrations of those ions in the solution in which the quartz is immersed. For quartz particles ranging in size from 0.2 to 1 mm, it was demonstrated that the concentration of calcium in solution (assumed present as ions) necessary to completely activate quartz for flotation is given by the expression: Ca++ = [H+] X 106 + [Na+] X 10-3 In this expression, ionic concentrations are in mols per liter. It was further shown that the pick-up method is apparently more sensitive to changes in reagent concentration than the standard captive-bubble method, and that induction times are apparently much reduced. Since completing these earlier tests, a new type of cell has been constructed; this is shown in Fig 1 and 2. In Fig 1, A is a ground joint, B is a central tube reaching to within a few millimeters of the bottom of the cell, and C is a stopper which may be removed for reagent addition, and serves the further purpose of excluding carbon dioxide from the air during the test. The entire cell is constructed of Pyrex glass, and does not give the trouble experienced with the earlier cell, in which activating ions were released from the glass at high pH values. The only critical factor in the construction of the cell is the clearance between the central tube and the bottom of the cell. This clearance should be sufficiently small that the bubble can be pressed directly on the mineral grains lying on the bottom of the cell. In the pick-up tests to be described in this paper, the reagents used were all of C. P. grade, except the sodium oleate, which was Merck's "neutral powder." The quartz employed was water-clear vein quartz, sized on screens, cleaned with both hydrochloric acid and sodium hydroxide, and given a thorough final washing with distilled water. Experimental procedures were the same as described in the earlier paper. EFFECT OF SIZE OF QUARTZ ON PICK-UP To ascertain the effect of particle size on the adsorption of calcium ions, the quartz was sized from minus 14 plus 20 mesh through the intervening screen sizes to minus 270 mesh plus 400 mesh. Each size was thoroughly cleaned, and then tested in the cell at different calcium chloride and sodium hydroxide concentrations, and at a constant sodium oleate concentration of 20 mg per liter. All particles, within the size range given, exhibited complete pick-up within the curve expressed by the equation above. This presumably means, when the conditions imposed by the equation are satisfied, that this maximum is independent of particle size. However, it was found that the range through which partial particle pick-up occurred progressively broadened as particle size decreased. This is shown in Fig 3, in which curves B, C, and D show the limits at which pick-up just commences (as the pH is increased) for particles of minus 14 plus 28 mesh, minus 65 plus 100 mesh, and minus 270 plus 400 mesh size, respectively. These results indicate that for satisfactory activation, at any given pH, a lower calcium ion concentration is required for fine particles than for coarse particles. EFFECT OF HIGH ALKALINITY ON PICK-UP At calcium concentrations of between 1 and 10 mg per liter, and at high alka-linities, it was noticed that pick-up ceased as soon as calcium hydroxide commenced to precipitate. This effect was investigated at other calcium concentrations, with the same results. Solutions of calcium chloride, containing 105, 104, l03, and l02 mg of calcium per liter were made alkaline with sodium hydroxide until calcium hydroxide just started to precipitate, according to the following equation: CaCl² + NaOH -+ Ca(OH)2 + 2NaCl The beginning of precipitation was taken as that point at which either a faint opalescence appeared in the solution, or a Tyndall cone became ap-

Jan 1, 1950

By J. E. Papin

MORENCI ores contain as an average about 0.015 pct molybdenite, MoS2. Incidental to the concentrating operations applied for the recovery of copper minerals, approximately two-thirds of the molybdenite is floated and appears in the final copper concentrate. The economic importance of molybdenum and the success achieved in its recovery in milling operations elsewhere encouraged research directed toward its recovery in marketable form. Several procedures are utilized to effect separation of molybdenite from copper and iron sulphides, but only two have wide application. In the better known of these two methods the molybdenite in the copper concentrate is depressed in a flotation operation using soluble starch as the depressant. The tailing from this treatment thus becomes a low-grade molybdenite concentrate which after thickening, filtering, and low temperature roasting is repulped with water and subjected to additional flotation steps for recovery of the molybdenite. A thio-phos-phate collecting agent is employed in flotation of the copper minerals. Presumably the stability and lasting effects of that collector type necessitated the practice of depressing molybdenite followed by subsequent roasting to insure elimination of copper and iron sulphides from final molybdenite concentrate. The second important method of recovery is applied at various southwestern plants. In those plants xanthates are in use as copper collecting agents. It has been found that xanthates are relatively unstable and their collecting power for sulphides is destroyed by very simple procedures. The method generally applied is to subject the xanthate-acti-vated concentrate, in the form of a pulp, to prolonged heating using steam as the heating medium. A concentrate thus treated may then be subjected to a flotation operation for recovery of the molybdenite, using mineral oil collecting agents, and the copper and iron sulphides will be depressed. Neither of the above processes was applicable to Morenci concentrates. Morenci uses a thio-phos-phate collecting agent in its flotation operation. However, it was established that soluble starch was not a depressant for Morenci molybdenite; therefore the first step in that process was not applicable. AS would be expected the copper and iron sulphides in Morenci concentrates could not be depressed by the heating methods used on xanthate activated concentrates. Low-temperature roasting did eliminate the effects of the thio-phosphate but had to be rejected as uneconomic in as much as the tonnage of concentrates involved was too great. Preliminary research having established the above facts, it became obvious that new methods would have to be developed for the recovery of molybdenite from Morenci concentrates. A broad laboratory investigation was initiated along two general lines, both directed toward depression of copper and iron sulphides. One approach was through the use of water-soluble oxidizing agents with the objective of destroying the thio-phosphate in the concentrate and thus eliminating its collector effect. The other approach involved the use of soluble sulphides, which have long been recognized as sulphide depressants. These efforts resulted in laboratory processes which showed promise. Research was then extended to a pilot plant having a daily capacity of several tons of concentrate. This operation soon demonstrated that soluble sulphide—basically sodium polysulphide—when applied to a pulp made slightly acid with sulphuric acid, proved to be the most effective sulphide depressant. The rate of concentrate treatment in this plant and the low molybdenite content of the concentrate prevented carrying the process to a conclusion, namely, production of molybdenite concentrate of marketable grade. Laboratory treatment of pilot plant concentrate indicated that a marketable product could be made from it, given a tonnage suited to available cleaner flotation machine capacity. Accordingly, the molybdenite plant was enlarged to permit treatment of the total copper concentrate from the extension plant, maximum of approximately 800 tons per day. In the enlarged plant a major difficulty was encountered. No criteria could be established as a basis for control of the process. In the early stages of flotation, because of the small amount of molybdenite involved, there was no visual evidence of the relative floatability of molybdenite with respect to

Jan 1, 1956

By C. Richard Tinsley

Like most minerals, coal is inherently a demand-limited commodity. The very sedimentary nature of its occurrence implies greater availability potential than demand. But this situation is overridden by economics among fuels, between coals, and within coal blends. Such considerations make coal forecasting a very hazardous profession indeed. THERMAL COAL If one thought that the lead times involved with a mining project were very long, one has obviously not been exposed to the planning process in the electric generation business - a process seriously confounded by shifts in load growth, environmental pressures, capital intensity, security of fuel sourcing, inter-fuel economics, and so on. But as a general rule, the near-term forecasts for thermal coal can reliably be based on a bottom-up, plant-by-plant analysis. Cement plant conversions can also be reasonably estimated next in order of reliability, although they have a much wider spectrum of coal qualities and fuel sources to choose from with a notably higher tolerance for sulfur and ash. Finally, industrial demand can be assembled from the estimates for conversions by pulp/paper plants, chemical plants, etc. The industrial sector is harder to estimate, since it may involve small boilers or dual-fired units. Assessing demand in the Pacific Rim is relatively a straightforward process in the near term because the major importing countries are all located on the Asian continent with either negligible or very minor (yet stable) indigenous coal production, (itself often operated on a subsidized basis). Furthermore, all imports are seaborne. These major importers are Japan, Korea, Taiwan, and Hong Kong with Thailand, Singapore, and Malaysia up-and-coming consumers. The suppliers to this market all have substantial reserves to back up decades of exports to these countries. Australia, the US, Canada, South Africa, China, and the USSR dominate the supply side. The second oil-shock of 1979/1980 has convinced the importers that reliance on oil can be expensive and eminently interruptible. Thus, they are determined to diversify away from oil' to nuclear and coal for generating electricity and for coal for other purposes where possible. This trend is seen to continue even in the face of the oil glut worldwide and oil-price reductions in early 1982. But the importers are also convinced that reliance on one coal source and, in particular, one infrastructure route for the coal chain from mine to consumer can be equally expensive and interruptible. Strikes in the US and Australia; excessive demurrage at certain ports; relegation of coal to a lower priority on multiple-use railroads in the USSR and China; and concern over escalation on high-infrastructure or high-freight coal chains are among the risks worrying the importers. As a consequence, Pacific Rim thermal coal purchases are being allocated among supplier nations, between ports, and within each country. An example of Japan's shift away from Australia and toward the US and Canada is shown in the estimates in Table 1. But the confidence of the import estimates deteriorates sharply beyond the plant conversion timetables and construction schedules in the near term. If part of the second generation of coal-fired power plants can handle lower-energy coals, the field of suppliers could widen to accept sizeable tonnages from Alaska, Wyoming, Alberta, or New Zealand resources. These supply sources generally have some infrastructure or freight advantage to compensate for their lower quality and to compete on a delivered energy-unit basis. These also offer diversification in sourcing. And the possibility of coal liquefaction in Japan further widens the sourcing network. A great number of Pacific Rim coal forecasts have been generated, especially for Japanese thermal-coal imports which are expected to grow strongly in the 1980's. Since the Japanese themselves have not yet settled their energy policy, the exact numbers are hard to call. Nevertheless, at 50 million tonnes of imports in 1990, Japan would consume 50-60% of the total Asian thermal coal imports as shown on Tables 2 and 6. The next most important consumers are the "island" nations of Korea, Taiwan, and Hong Kong (see Tables 3-5). All three are embarking on power plant developments usually with captive unloading facilities, capable of accepting more than 100,000-dwt vessels. Korea, with no-indigenous bituminous coal, is not especially enamoured with US coals, which are deemed too heavily loaded by freight and infrastructure costs -- up to 70% of the delivered price. Thermal coal contracts are presently split to Australia (70%) and to Canada (30%). Korea Electric Power Co. is already considering second-generation boilers capable of burning lower-quality coals than the present standard. Korea does burn domestic anthracite.

Jan 1, 1982

By Rodolfo V. de la Cruz, Richard E. Goodman

Knowledge of the initial state of stress in rocks provides a key to the solution of many problems in rock mechanics. The initial state of stress is part of the basic data required for rational design of structures in rock, since its redistribution when engineering activities are conducted is a primary load on the rock portion of the engineering system. Knowledge of initial and subsequent changes in the state of stress is also relevant in the study of active faults and crustal strain. The purposes of stress measurements are not generally well served by methods which disclose only one of the stress components at a point. Recently, interest has centered on overcoring methods which though ex- pensive and difficult have the important advantage of yielding data on three or more stress components. In a previous paper, the authors introduced a new method-termed borehole deepening-based on measurement of the deformations that occur close to the bottom of a borehole when it is deepened by further drilling without overcoring.l The proposed method is at a disadvantage when compared with over- coring procedures in that the quantities to be measured are somewhat smaller and the measuring environment is more hostile. However, the borehole deepening method presents three distinct advantages in comparison with overcoring procedures: (1) Using the same borehole, both the initial and the subsequent changes in the state of stress can be obtained by borehole deepening. Stress changes with time are

Jan 1, 1970

By C. K. Eilerts

Finite difference equations were programmed and used to integrate the second-order, second-degree, partial differential equation with variable coefficients that represents the transient linear flow of gas-condensate fluids. Effect was given to the change with pressure of the compressibility factor, the viscosity, and the effective permeability and to change of the absolute permeability with distance. Integrations used as illustrations include recovery of fluid from a reservoir at a constant production rate followed by recovery at a declining rate calculated to maintain a constant pressure at the producing boundary. The time required to attain such a limiting pressure and the fraction of the reserve recovered in that time vary markedly with properties of the fluid represented by the coefficients. Fluid also is returned to the reservoir at a constant rate, until initial formation pressure is attained at the input boundary, and then at a calculated rate that will maintain but not exceed the limiting pressure. The computing programs were used to calculate the results that would be obtained in a series of back-pressure tests made at selected intervals of reservoir depletion. If effect is given to the variations in properties of the fluid that actually occur, then a series of back- pressure curves — one for each stage of reserve depletion — is required to indicate open-flow capacity and related flow characteristics dependably. The isochronal performnce method for determining flow characteristics of a well was simulated by computation. INTRODUCTION The back-pressure test procedurel is based on a derivation of the equation for steady-state radial flow of a gas, the properties of which are of necessity assumed to remain unchanged in applying the test results. The properties of most natural gases being recovered from reservoirs change as the reserve is depleted and pressures decline, and the results of an early back-pressure test may not be dependable for estimating the future delivery capacity of a well. The compressibility factor of a fluid under an initial pressure of 10,000 psia can change 45 per cent and the viscosity can change 70 per cent during the productive life of the reservoir. There are indications that the effective permeability to the flowing fluid can become 50 per cent of the original absolute permeability before enough liquid collects in the structure about a well as pressure declines to permit flow of liquid into the well. The advent of programmed electronic computing made practicable the integration of nonlinear, second-order, partial differentia1 equations2.3 pertaining to flow in reservoirs. Aronofsky and Porter4 represented the compressibility factor and the viscosity by a linear relationship, and integrated the equation for radial flow of gas for pressures up to 1,200 psi. Bruce, Peaceman, Rachford and Rice5 integrated the partial differential equations for both linear and radial unsteady-state flow of ideal gas in porous media. Their published results were a substantial guide in this study of integration of the partial differential equation of linear flow with coefficients of the equation variable. The computing program was developed to treat effective permeability as being both distance-dependent and pressure-dependent. In this study all examples of effective permeability are assumptions designed primarily to aid in developing programs for giving effect to this and other variable coefficients. The accumulation of data for expressing the pressure dependency of the effective permeability is the objective of a concurrent investigation. FUNDAMENTAL DIFFERENTIAL EQUATIONS DIFFERENTIAL EQUATION OF FLOW Linear transient fluid flow is represented by the partial differential equation,

Jan 1, 1965

By F. V. Hicks

THE similarity of mining practices in bituminous coal fields through-out America is due to the fact that certain fundamental conditions are encountered in all fields. The problems of labor, housing and mining are somewhat similar whether the mine is in Pennsylvania, Illinois, Wyoming or the State of Washington. Each field has had its particular problems, resulting in advantages or disadvantages over a competing field. This might take the form of a wage differential, a better natural condition more favorable to cheap production, or proximity to a market that allows freight rate advantages, etc. In any event, no matter how favorably situated, the mining companies that have been slow to recog-nize and accept the advantage of mechanization, clinging too long to the old hand methods, have found themselves unable to meet competition. Throughout the Wyoming coal fields, production methods have so changed in the last decade as to be almost unrecognizable to an old-time coal miner who has had no connection with the industry during; that period. The old contract system, with its peculiar labor relationship between employer and employee, based upon the long-established custom that the miner's working place was his castle, and that it was his privilege to carry on operations within that place largely in his own way and to his own liking, is a condition that has passed away. The present-day, 100 per cent mechanized mine bears but little resemblance to the old. A change -in system has naturally altered the old-time labor relationship. Contract labor has been almost entirely eliminated and a straight day-wage basis established, with certain classes of work calling for different rates, which places the entire personnel of the underground operating force more directly under the direction and supervision of the mine foreman and his assistants. The transition from the old order to the new has gradually done away with the system of penalties, personal- rights and privileges existing under the contract system, which were so controversial in the past that the average mine management was constantly involved in labor disputes in fields where organized labor was employed.

Jan 1, 1936

By Gerald A. Munson, Fremont F. Clarke

DURING recent years the use of lithium has expanded greatly in industrial, chemical, and metallurgical fields, while at the same time modernized methods of mining and refining lithium have increased production. Technical literature includes many papers describing the geology and mineralogy of lithium deposits. Mining and beneficiating problems, however, have not been thoroughly described. Published reports have failed to emphasize that one of the chief reasons lithium minerals were not extensively mined until recently is the difficulty of beneficiation. Four lithium minerals of pegmatites and the lithium-sodium-phosphate byproduct from the brines at Searles Lake, Calif., have been sources of lithium. Among the pegmatite minerals, only spodu-mene and petaline are known to occur in deposits large enough to support large tonnage operations. Spodumene, a lithium-aluminum-silicate, is the principal lithium mineral mined in the U. S. Lithium Corp. of America, during its rapid development and growth, has successfully employed three different methods of concentration: 1) hand sorting, 2) Heavy Media separation, and 3) froth flotation. Each method, though economic in its sphere, is becoming outdated as extractive techniques improve. The most recent development has taken place at Lithium Corp.'s new operation in North Carolina, where the extractive process yields lithium compounds directly from mined rock without an intervening concentrating step. Until 1954 Lithium Corp. mined only in the southern part of the Black Hills of South Dakota, where the various types of lithium-bearing pegmatite could be used to develop untried processes of beneficiation. Concentrates from these operations are shipped to the corporation's chemical plant in St. Louis Park, Minn., where actual extraction of lithium and production of commercial compounds takes place. Nature of Deposits The geology of the southern Black Hills pegmatite deposits is admirably presented by a U. S. Geological Survey publication.' Only the factors pertinent to exploitation need be mentioned here. Lithium Corp. has been interested primarily in three deposits, the Edison, the Mateen, and the Longview-Beecher No. 2. The history of these deposits dates back to the mining boom of 1880 to 1900 in the Black Hills, when most of the deposits were prospected for tin by the ill-fated Harney Peak Tin Mining Co. The three deposits described here, however, lay idle and unwanted until Lithium Corp. opened the Edison mine in 1943 and the Mateen and Longview-Beecher No. 2 in 1951. Edison Deposit: The Edison deposit is about a mile southeast of Keystone, S. D., on the northeastern flank of the Harney Peak uplift. The deposit consists of no less than four and probably at least six separate pegmatites that coalesce in a central mass from which the individual pegmatites finger outward and downward in complexly folded schist and gneiss beds of the country rock.

Jan 1, 1956

THE good and lofty men of intelligence are constantly discoverers of many beautiful things, because of their kindness or because they are driven by necessity. Either they shorten the method of making them after they have seen them, or they think how they can be increased in power or how they can be used for various effects in addition to the one intended by the inventor. Certainly all the effects described to you in this Tenth Book derive from gunpowder. When so many proper- ties and so much strength were observed in this, it was thought that by enclosing it in some strong thing that had the power to resist it, gunpowder would produce a marvelous effect. And thus they made a tube of bronze or iron [160v] which they closed with a wooden plug. They applied fire, and when they saw how forcefully this plug issued they thought of making one that would come out and strike in order to destroy things. They made an instrument of bronze or of iron and put some powder and a round stone inside, and called it a spingard. Developing then from this,

Jan 1, 1942

By R. G. Bowman

LEAD is a dull and sober metal, and in times of economic stress it en- joys, or at least occupies, a position which partakes somewhat of its physical lethargy and stability. The past ten years have witnessed in this country a decline in the production of lead, and a shrinkage of ore reserves, following closely the general economic situation. Metal prices have not justified exploration and development of new sources. Momentary rallies in industry have brought no response from lead.

Jan 1, 1940

By Frederick Prime

THE Great or Cumberland Valley, which (under a variety of names) extends from Canada, through Vermont, Massachusetts, Connecticut, New York, Pennsylvania, Maryland, Virginia, and East Tennessee, to Alabama, is composed in part of limestones lying immediately above the Potsdam sandstone. Geologically, they belong to the era between the Potsdam and Trenton, and are commonly termed Calciferous. A peculiarity of these limestones is their great richness in limonite or brown hematite ores, which form a large part of the charges of the many blast-furnaces situated on their outcrops. The mines from which the ores are obtained are (properly speaking) only pits or quarries, from which the ore is extracted by means of picks or shovels, powder being rarely employed. The ore does not occur casually at any point in the limestone, but forms regular lines, following apparently the 'outcrops of certain beds. In Lehigh County, Penn., where I have been engaged on the Geological Survey of' the State, during the past season, there are three or four of these lines. During the progress of the survey I was much struck by the fact that the two most important and promising lines of outcrop were, one at the base of the crystalline schists (forming the South or Lehigh Mountain), and overlying the Potsdam sandstone conformably; the other, near the line of junction of the calciferous limestone with the slates of the Cincinnati epoch. The mines along these two lines, following the topography of the country, were in place, richer and more permanent than those of the belts between, which were generally leaner. A peculiarity of these two lines of outcrop, and one to which I particularly desire to draw attention, is the occurrence of what I at first mistook for a highly altered slaty limestone, but which subsequent analysis proved to consist in great part of damourite (hydrated potash mica). The following are analyses of this damourite slate I. From Fogelsville, Lehigh County, within a few hundred feet of the contact of limestone and slate, by Dr. F. A. Genth. II. From Hensingerville, Lehigh County, within 300 feet of gneiss, by Mr. Sydney Castle, of the University of Pennsylvania. III. From Allentown, Lehigh County, within 150 feet of con-

Jan 1, 1875

By B. O. Pickard

With more than a score of shafts and numerous stope openings to the surface, all inter-connected underground; with underground temperatures high, often exceeding 100' wet bulb; with an ore presenting a dust health-hazard; with certain rocks giving off inert gases; with an altitude of 6000 ft. above the sea level and a dry desert climate, the Tonopah mines offered an interesting problem to the student of metal-line ventilation. Tonopah is not an old mining district, relatively speaking. It was discovered in 1900 and Tonopah soon was a boom camp. Ry 1910 the mines of this district had paid many millions of dollars in dividends. At the time of the 1921 ventilation study, mining had passed its peak of production and the operators were striving to reduce costs, to discover new orebodies, and to attract desirable workmen. In 1925, the camp was operating on a still less prosperous basis, but the several managements had not relaxed in their efforts to keep the mines on a paying basis, neither had they lost their faith in the ability of the mines and the price of the silver to "come back." Early in the fall of 1921 the Bureau of Mines was invited by the mine operators at Tonopah, Nev., to make a detailed study of the underground air conditions in the Tonopah silver district. D. Harrington, chief engineer of the Safety Service Division of the Bureau, who was then directly supervising the ventilation studies, detailed district engineer B. 0. Pickard, mining engineer E. D. Gardner, surgeon C. E. Kindall, and petrographer IT. Insley to carry on the study. G. S. Rice, as chief mining engineer of the Bureau of Mines, was in general charge of the work. Upon the completion of the study each operator was furnished a report on conditions in his mine. In 1925, a supplemental study at Tonopah was made by the district engineer at the request of several of the operators, and each operator advised on the changes in his respective air conditions and recommendations for improvements. Recently, several of the operators gave the

Jan 1, 1927

By Will B. Jamison

It is a fact that the most serious safety problems encountered in US underground coal mines are related to roof-bolting operations. It is also true that roof bolting is usually the operation which limits coal production from a mine section. There has been a recent focus on activity involving roof bolting research, development, and new ideas as people concerned about mine worker safety and productivity realize that significant progress can be made in these areas, even with equipment presently available.

Jan 7, 1977

By R. H. Tien

The accuracy of the method of steady-state approximation applied to the problems of heat transfer involving phase change (London and Seban's solution) is improved by defining a "modified heat of fusion" which accounts for the effect of specific heat. An analytical expression for this modified heat of fusion is derived in terms of the actual heat of fusion, specific heat, and surface temperature. Numerical solution for the freezing of iron indicates that the ratio of the modified heat of fusion to the actual heat of fusion increases from 1.04 to 1.4 as the surface temperature decreases from 2700° to 1600°F. The heat transfer process accompanying solidification is complicated owing to the moving solid-liquid interface where the latent heat of fusion is released. Exact analytical solution is available only for a few special cases of freezing problems such as Stefan's1 problem. In a commonly used steady-state approximation method, London and seban's2 solution, the effect of specific heat is neglected. This approximation, however, may introduce some degree of error in mathematical analysis when the temperature of the solid surface is much lower than the freezing temperature, as in the case of freezing metals. In a recent work by Robertson and Schenck,3 the problem of freezing a semi-infinite region with finite surface conductance was programed in a digital computer through the finite difference method. A family of curves for the correction of the London-Seban solution was given in a dimensionless plot for different ratios of heat of fusion and specific heat effect; it was shown that the London-Seban solution when applied to the freezing of a mild steel slab under some particular conditions gave results in error by about 10 pct in the solidification rate. Although the Robertson-Schenck computer result has improved the London-Seban solution to a great extent, lack of generality and the tedious computing procedure have restricted its application. In this paper a "modified heat of fusion" which accounts for the effect of specific heat is defined, and is used instead of the actual heat of fusion in the London-Seban solution. An analytical expression of this modified heat of fusion in terms of the specific heat, surface temperature, and actual heat of fusion is derived by comparing the solutions of Stefan and London-Seban for the case of freezing of a semi-infinite region with constant surface temperature. It can also be extended to the case with finite surface conductance, and the results show good agreement with the Robertson-Schenck computer solution. The expression of the modified heat of fusion, the accuracy of the London-Seban solution, and the temperature distribution within the solid are presented graphically in dimensionless form. Numerical solution for the freezing of iron indicates that the ratio of the modified heat of fusion to the actual heat of fusion increases from 1.04 to 1.40 as the surface temperature decreases from 2700° to 1600°F.

Jan 1, 1969

By D. Jenkins

The Franklin Laboratory was designed mainly for the analysis of the products from the two concentrating mills situated at Franklin and Sterling Hill, the most important determinations being the zinc, iron, manganese, lime, moisture, and silica contents of the ores. Within the last 4 years, however, it has been found advisable to examine most of our supplies, and therefore additional space and equipment was allotted for the examination of such substances as oils, greases, soaps, alloys, fuels, paints, explosives, and water. The building as shown in elevation (Fig. 1) and plan (Fig. 2) consists of a main or routine laboratory, an experimental laboratory, a water analysis room, and the other accessories such as stock room, library, sampling and drying rooms, and office. The main laboratory is further divided into a balance room and zinc analysis room. As the greater part of our determinations are volumetric, good light is a very important factor and with this in view the interior malls of the building were constructed of white enameled brick laid in Keene cement. These also have the additional advantage that they give a clean and attractive appearance to the room. The windows are large, being 76 by 44 in. and even on very dark days the light is good throughout the whole laboratory. Our zinc titration requires a constant light and as, on many days, especially in winter, the light is variable, we installed two Artificial

Jan 1, 1918

NEW MEMBERS. The following list comprises the names of those persons who became members during the month of November, 1913: Members. AGNEW, JOHN L., Gent Supt Copper Cliff, Ont., Canada. BAILEY, FRANK C, Mine Mgr 2003 IV. Snito Ave., Spokane, Wash. BATEMAN, ALAN M., Min. Geol.,Care L. C. Graton, Geological Museum, Cambridge,Mass. BERRYHILL, JAMES G.,Atty.-at-law and Mining Investor, Equitable Bldg., Des Moines, Ia. CARTLIDGE, OSCAR, Mgr. State Mine Rescue Station, 452 W. South Grand Ave.. Springfield. Ill.

Jan 12, 1913

By H. R. Froning, R. O. Leach

In wertability alteration flooding, a chemical agent is rnoved through a reservoir by the flood water to increase oil recovery by decreasing the degree of wetting of the rock by the oil. Substantial amounts of the chemical may be lost during movement through the reservoir. The extent of the loss, and therefore the economics of the process, depends in some cases on factors which are difficult to reproduce in the laboratory. Therefore, a short-duration, low-cost field test method is needed to permit evaluation of chemical requirements under actual field conditions. This paper describes a small scale rest conducted at a single well for measuring chemical requirements, thereby giving a more reliable evaluation of this important factor in the applicability and economics of the process. In the rest a small wafer slug containing the chemical agent and a nonadsorbed tracer is displaced into the reservoir by a known volume of wafer. The well is then placed on producrion. Chemical loss per barrel of pore volume contacted is calculated from [he fractional recoveries of the agent tested and the nonadsorbed tracer. The method has been used to determine within the actual reservoirs the chemical requirements for both a sandstone and a dolomite reservoir. Several chemical agents are potentially available for wettability alteration flooding, although none is universally applicable. For some applications of the method, chemical costs per barrel of additional oil recovered can be substantially less than one dollar. INTRODUCTION Wettability alteration flooding provides a means of increasing oil recovery from reservoirs by decreasing the degree of wetting of the rock by the oil and increasing the displacement efficiency of the flood water. Earlier studies demonstrated a relationship between oil recovery during waterflooding and the degree of wetting of a rock surface by an oil. The application of wettability alteration flooding to the Harrisburg field of Nebraska provided a field test' of this recovery process. Subsequently, additional laboratory and field tests have developed additional procedures for evaluating wettability alteration flooding, and have indicated where the process may be applicable. Applicability of this process to specific reservoirs is determined by a progression of tests to determine sus- ceptibility of the reservoir to alteration of its wettability, to indicate the degree of recovery improvement and to estimate the amount of chemical required to process the reservoir. The economics of applying improved oil recovery processes depends not only upon the degree of improvement in oil recovery achievable by the process but also upon the process costs and the timing of the income and the investment. Emphasis in this paper is on the expenditure aspects of the process. The work reported in this paper indicates that the chemical investments required for wettability alteration flooding are substantial. For evaluating the economics of a potential flooding application it is imperative that a sound estimate of the chemical requirements be made for the reservoir. Generally, true reservoir conditions are not adequately simulated in laboratory chemical propagation tests. Because of wide well spacings, many years might be required to obtain chemical propagation data from conventional pilots or inter-well tests. Consequently, n short-duration, low-cost method is needed to determine chemical requirements in the field. The potential applicability of wettability alteration flooding is discussed, as well as the economics of wettability alteration with respect to the inherent and imposed restrictions on the timing of income and investments. DETERMINATION OF CHEMICAL REQUIREMENTS In the process of moving a chemical bank through reservoir rock, some of the chemical agent lags too far behind the flood front to be effective or is otherwise lost to the reservoir system. The extent to which these losses occur overshadows the reductions in chemical concentration due to diffusion and to mixing with the reservoir fluids. Experience indicates that almost without exception, chemicals which induce a wetting change undergo either sorption reactions or chemical reactions with mineral constituents of the pore surfaces. Other reactions may occur between the added chemical and the reservoir oil and water. Even in limiting consideration to reactions of the relatively inexpensive inorganic salts, bases and acids, the reactions may be exceedingly complex. Reservoir pore surfaces consist of more than silica in sandstone reservoirs, and more than calcite or dolomite in carbonate reservoirs. Many mineral species are present, each exhibiting specific tendencies to react with an injected chemical. The reactions which occur can consume enough of the agent to have an important effect on economics. These reactions can cause a change in pH of the chemical bank, or may remove some of the active chemical by precipitation, adsorption or reaction to form a new chemical which may or may not be effective in