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By G. H. Clevenger

The reagents now used in flotation consist of various acids or salts, which may be either electrolytes or non-electrolytes, dissolved in water and some substance or combination of substances which function as collecting or frothing agents. At times the only dissolved salts present are those naturally occurring in the water used. The general effect of the electrolyte is to greatly sharpen the separation between the gangue and the concentrate. Examples of this are: The use of sulphuric acid with zinc ores; and of sodium carbonate or calcium oxide (lime) with silver-gold ores. Crude pyroligneous acid is also sometimes used when avail able. Various oxidizing agents, such as permanganates, bichromates, etc., are added in the selective flotation of lead-zinc ores. Many other reagents for performing certain specific functions, either real or imaginary, have been proposed, and a number of them have been tried upon a working scale. The wild orgy of experimentation which is now going on in flotation exceeds even that which followed the introduction of the Washoe process for the treatment of Comstock ores, when, among other things, sage-brush tea and tobacco juice were reagents added to the pans. Out of all this will, of course, eventually come a more or less standard practice for the treatment of each class of ore. Omitting a discussion of the functions of frothing and collecting agents, the reagents used in flotation for this purpose may be classified under five general heads: (1) Essential oils; (2) fixed or fatty oils; (3) alcohols and their combinations with organic acids; (4) coal tar and its refined products; (5) petroleum and its refined products. A flotative agent of some kind is required in flotation as now practiced. A single reagent, as, for example, certain of the essential oils, may perform the dual function of frothing and collecting agent, or a mixture of substances may be required. In this country, the essential oils used have been wood products, and have been almost exclusively confined to the steam-distilled pine oils. At the present time, the supply of these is limited, and the cost almost prohibitive, so that their use has been dispensed with as far as possible. The oils and tars resulting from the destructive distillation of

Jan 1, 1917

By Harold Markus, Gerhard Derge, Arthur Grobe

THE high corrosion resistance possessed by tin under most circumstances, combined with its generally satisfactory appearance and useful physical properties, has led to many and varied uses for the metal. These uses have been partly limited by the fact that tin is an expensive metal, therefore many applications have been developed in which tin has been employed in combination with lead, either by coating, as in tin-lined collapsible tubes, or by the formation of alloys containing various proportions of tin-rich and lead-rich phases, as terne plate. A detailed knowledge of the corrosion characteristics of the tin-lead couple therefore is of general interest and has become specially important at the present time, when every effort is being made to conserve tin as much as possible. The present study has been limited to carbonate solutions with a pH range from 8.4 to 11.2 so that the results may be related to earlier work on the corrosion of tin and its alloys.1-3,6 In these papers, the effects of a number of anion and cation additions to these solutions have been observed. APPARATUS AND METHOD The electrodes for the corrosion cell were cut from rolled sheet about 1/16 in. thick. The length of all specimens was held constant at 7 in., while the width was varied from ½ to 2 in. These electrodes were fastened to brass electrode supports, which were attached to rubber stoppers fitting into tall-type one-liter Pyrex beakers that contained the electrolyte. The lead electrodes were prepared from Omaha pig* and the tin was rolled from a slab of Chempur.† After cutting to size, the sheets were polished with No. I emery paper and cleaned with carbon tetrachloride. The edges, back and upper parts of the specimen were coated with a synthetic lacquer, which was supplemented with beeswax for the lead electrodes. The binding posts were coated with beeswax after the electrodes had been clamped. The pH of the electrolyte was controlled by adjusting the ratio of carbonate to bicarbonate. Approximately 600 ml. of electrolyte was used in each beaker. The entire assembly was placed in an oil bath thermostatically adjusted to operate at 30°C. ± 0.1°. Potentials were measured against a saturated calomel electrode connected to the cell by an agar-agar salt bridge. The carbonate solution used in the salt bridge was the same as that used in the corrosion cell. Currents were measured with a milliam-

Jan 1, 1942

By Gerhard Derge, Arthur H. Grobe, Harold Markus

The high corrosion resistance possessed by tin under most circumstances, combined with its generally satisfactory appearance and useful physical properties, has led to many and varied uses for the metal. These uses have been partly limited by the fact that tin is an expensive metal, therefore many applications have been developed in which tin has been employed in combination with lead, either by coating, as in tin-lined collapsible tubes, or by the formation of alloys containing various proportions of tin-rich and lead-rich phases, as tcrne plate. A detailed knowledge of the corrosion characteristics of the tin-lead couple therefore is of general interest and has become specially important at the present time, when every effort is being made to conserve tin as much as possible. The present study has been limited to carbonate solutions with a pH range from 8.4 to 11.2 so that the results may be related to earlier work on the corrosion of tin and its alloys. 1-3,6 In these papers, the effects of a number of anion and cation additions to these solutions have been observed. Apparatus and Method The electrodes for the corrosion cell were cut from rolled sheet about 1/16 in. thick. The length of all specimens was held constant at 7 in., while the width was varied from M to 2 in. These electrodes were fastened to brass electrode supports, which were attached to rubber stoppers fitting into tall-type one-liter Pyrex beakers that contained the electrolyte. The lead electrodes were prepared from Omaha pig* and the tin was rolled from a slab of Chempur.† After cutting to size, the sheets were polished with No. I emery paper and cleaned with carbon tetrachloride. The edges, back and upper parts of the specimen were coated with a synthetic lacquer, which was supplemented with beeswax for the lead electrodes. The binding posts were coated with beeswax after the electrodes had been clamped. The pH of the electrolyte was controlled by adjusting the ratio of carbonate to bicarbonate. Approximately 600 ml. of electrolyte was used in each beaker. The entire assembly was placed in an oil bath thermostatically adjusted to operate at 30°C. + 0.1". Potentials were measured against a saturated calomel electrode connected to the cell by an agar-agar salt bridge. The carbonate solution used in the salt bridge was the same as that used in the corrosion cell. Currents were measured with a milliam-

Jan 1, 1942

By Harold Markus, Arthur H. Grobe, Gerhard Derge

The high corrosion resistance possessed by tin under most circumstances, combined with its generally satisfactory appearance and useful physical properties, has led to many and varied uses for the metal. These uses have been partly limited by the fact that tin is an expensive metal, therefore many applications have been developed in which tin has been employed in combination with lead, either by coating, as in tin-lined collapsible tubes, or by the formation of alloys containing various proportions of tin-rich and lead-rich phases, as tcrne plate. A detailed knowledge of the corrosion characteristics of the tin-lead couple therefore is of general interest and has become specially important at the present time, when every effort is being made to conserve tin as much as possible. The present study has been limited to carbonate solutions with a pH range from 8.4 to 11.2 so that the results may be related to earlier work on the corrosion of tin and its alloys. 1-3,6 In these papers, the effects of a number of anion and cation additions to these solutions have been observed. Apparatus and Method The electrodes for the corrosion cell were cut from rolled sheet about 1/16 in. thick. The length of all specimens was held constant at 7 in., while the width was varied from M to 2 in. These electrodes were fastened to brass electrode supports, which were attached to rubber stoppers fitting into tall-type one-liter Pyrex beakers that contained the electrolyte. The lead electrodes were prepared from Omaha pig* and the tin was rolled from a slab of Chempur.† After cutting to size, the sheets were polished with No. I emery paper and cleaned with carbon tetrachloride. The edges, back and upper parts of the specimen were coated with a synthetic lacquer, which was supplemented with beeswax for the lead electrodes. The binding posts were coated with beeswax after the electrodes had been clamped. The pH of the electrolyte was controlled by adjusting the ratio of carbonate to bicarbonate. Approximately 600 ml. of electrolyte was used in each beaker. The entire assembly was placed in an oil bath thermostatically adjusted to operate at 30°C. + 0.1". Potentials were measured against a saturated calomel electrode connected to the cell by an agar-agar salt bridge. The carbonate solution used in the salt bridge was the same as that used in the corrosion cell. Currents were measured with a milliam-

Jan 1, 1942

By Harold Markus, Arthur H. Grobe, Gerhard Derge

THE high corrosion resistance possessed by tin under most circumstances, combined with its generally satisfactory appearance and useful physical properties, has led to many and varied uses for the metal. These uses have been partly limited by the fact that tin is an expensive metal, therefore many applications have been developed in which tin has been employed in combination with lead, either by coating, as in tin-lined collapsible tubes, or by the formation of alloys containing various proportions of tin-rich and lead-rich phases, as terne plate. A detailed knowledge of the corrosion characteristics of the tin-lead couple therefore is of general interest and has become specially important at the present time, when every effort is being made to conserve tin as much as possible. The present study. has been limited to carbonate solutions with a pH range from 8.4 to 11.2 so that the results may be related to earlier work on the corrosion of tin and its alloys.1-3,6 In these papers, the effects of a number of anion and cation additions to these solutions have been observed. APPARATUS AND METHOD The electrodes for the corrosion cell were cut from rolled sheet about 1/16 in. thick. The length of all specimens was held constant at 7 in., while the width was varied from 1/2 to 2 in. These electrodes were fastened to brass electrode supports, which were attached to rubber stoppers fitting into tall-type one-liter Pyrex beakers that contained the electrolyte. The lead electrodes were prepared from Omaha pig* and the tin was rolled from a slab of Chempur.? After cutting to size, the sheets were polished with No. I emery paper and cleaned with carbon tetrachloride. The edges, back and upper parts of the specimen were coated with a synthetic lacquer, which was supplemented with beeswax for the lead electrodes. The binding posts were coated with beeswax after the electrodes had been damped. The pH of the electrolyte was controlled? by adjusting the ratio of carbonate to bicarbonate. Approximately 600 ml. of electrolyte was used in each beaker. The entire assembly was placed in an oil bath thermostatically adjusted to operate at 30°C. ± 0.10. Potentials were measured against a saturated calomel electrode connected. to the cell by an agar-agar salt bridge. The carbonate solution used in the salt bridge was the same as that used in the corrosion cell. Currents were measured with a milliam-

Jan 1, 1942

By C. W. Volek, G. Mandl

Steam-injection tests in the field have shoum that heat transport into the oil/water region, ahead of the steam zone, may have a significant effect on the production process. Earlier theoretical work on reservoir heating by hot-fluid injection can be used to describe the growth of the steam zone, but only if heat transport from steam zone into oil/water region is neglected. It therefore became necessary to re-examine and extend the earlier theory. It was found that this theory ceases to be consistent with the physical model of the process at a certain critical time, tc, which depends on reservoir thickness, temperature, and quality of the steam. The critical time marks an important change in the heat flow across the condensation frovt: the heat flow, which is purely conductive during 0 < t < tc&apos; becomes predominantly convective at t = tc. Accordingly, at t = tc, the equation which governs expansion of the steam zone changes. On the basis of the new equation, an approximate description for the steam-zone growth during t > tc is developed by making use of upper and lower bounds for the exact solution of the problem. The boundary conditions for heat and mass flow inside the oil/water region are established, and a simple method of detennining the saturation at the downstream side of the condensation front is presented. Experimental results show that the theory gives an accurate description of steam-zone expansion before the critical time. At times near critical time, and also after critical time, experimental data show theoretical steam-zone volumes to be high. Even so, the accuracy of the calculated steam-zone volumes is sufficient for practical purposes. THEORY OF STEAM-ZONE GROWTH INTRODUCTION The engineering evaluation of steam-drive processes is based mainly on a mathematical description of reservoir heating by hot fluid injection presented several years ago by Marx and Langenheim.l This theory can be used to determine the growth of the steam zone,2 provided the flow of heat from the steam zone into the liquid zone ahead of the condensation front (Fig. 1) is neglected. Since we must expect, however, that heat transport into and inside the liquid region (the region between condensation front and production wells) will affect both the water/oil flow and the growth of the steam zone, it is necessary to re-examine and to generalize the Marx and Langenheim theory as applied to steam drive, which will hereafter be termed the "old" theory. Observations made in several field tests emphasize the need to study the heat flow across the condensation front (CF). On several occasions it was discovered that heat was transported in the liquid zone far ahead of the advancing CF, resulting in an early breakthrough of warm water. This seems to occur most often when high injection pressures are applied, when "wet" kONINKLIJKE/SHELL EXPLORATIE EN PRODUKTIE LABORATORIUM RIJSWIJK, THE NETHERLANDS SHELL DEVELOPMENT CO. HOUSTON, TEX.

Jan 1, 1970

THERE can be little doubt in the mind of anyone of the great interest which has been provoked in the mining and petroleum industry by the com-paratively new geophysical methods of prospecting, after the sessions at this year&apos;s meeting of the Institute. Not only were the sessions very well attended but every¬one seemed most attentive. Although the discussion was somewhat limited in general, that may well be at-tributed to the newness of the subject. Two sessions on this subject were planned originally, but these gave insufficient time for the presentation of all the papers prepared and a third session was abso-lutely necessary. The first meeting dealt entirely with the gravity methods and was completed in the scheduled time owing to the fact that but two of the five papers listed were read. The second session was devoted to magnetic and electrical methods, the completion of which had to be carried over into the third period of geophysics. The first session on geophysical prospecting, and in-cidentally the first scheduled Institute meeting devoted entirely to this subject, was most appropriately opened by E. L. DeGolyer, the chairman of the session. It was through the efforts of Mr. DeGolyer that the first gravity work, as applied to prospecting, was under-taken in this country. Again most appropriately, the first paper presented was given by Donald C. Barton, who carried on the first work with the Eötvös torsion balance in America and aided materially in its development. A subject, the theory of which is so difficult to understand as it is generally presented, was so clearly illustrated and ex-plained by the speaker that even a novice could grasp the fundamentals. Dr. Barton, in showing actual re-sults obtained in torsion balance surveys with the in-terpretation of the sane and later drilling records, was free in stating that there are many limitations to the field in which this and the other geophysical instruments may be successfully employed. This paper called for considerable discussion relative to the application of the torsion balance to gravity surveys over various types of structures. During the course of this discus-sion a very important point was emphasized by the chairman, namely, that for successful application of any or all of the scientific methods of prospecting, a back-ground of experience is absolutely necessary to serve as a basis for further work. This can only be secured by contributions from the results of actual prospecting work.

Jan 3, 1928

By G. D. Boozer, W. H. Somerton

RESEARCH CORP., LA HABRA, CALIF. Thermal diffusivities of some typical sedimentary rocks have been measured by a rapid unsteady-state technique. Thermal data including diffusivity and conductivity are presented for the temperature range of 200" to 1,800°F. Diffusivities calculated from steady-state conductivity rneasurernents compared favorably with unsteady-state data at the lower temperatures. Unsteady-state data are less reliable at higher temperatures; reported values may be as much as 20 per cent high at temperatures in excess of 1,500°F. This is caused partly by the simplified method used in calculating diffusivity from experimental data and partly by the many thermal reactions which occur at the higher temperatures. The marked decrease in thermal diffusivity and conductivity at elevated temperatures indicates the importance of considering the temperature dependence of thermal properties in subsurface heat-transfer calculntions. Knowledge of the effects of liquid saturation, overburden and pore pressures, and heats of reaction of reservoir materials will be required before complete subsurface thermal analyses may be made. INTRODUCTION Heat-transfer calculations are becoming increasingly important in the analysis of in situ combustion and underground nuclear explosions. Thermal data for natural rock materials at elevated temperatures are generally unavailable. Calculations at high temperatures may be grossly inaccurate if temperature-dependent thermal properties of rocks are not considered. It is known that the heat capacities of rocks increase with temperature. Heat capacities may be calculated from chemical or mineralogica1 analyses of the rock system. Thermal bulk expansion of rocks is believed to be small, although few data are available. Thermal conductivities of most natural rock materials decrease with increased temperature. Thermal diffusivity, defined as the thermal conductivity divided by the product of the heat capacity and the bulk density of the material, is used in unsteadv-state heat-transfer calculations. It is apparent that thermal diffusivity decreases markedly with increased temperature. A new method, which gives a nearly continuous record of thermal diffusivity within the temperature range of 200° to 1,800°F and requires less than 1.5 hours for the run,&apos; was used to measure the diffusivity of several sedimentary rocks. Thermal conductivities were calculated from measured bulk densities, heat capacities calculated from chemical analysis and the measured diffusivity values. Thermal conductivities were measured at lower temperatures by a steady-state technique1 to test the agreement of data obtained by the two methods.

By George A. Roberts

The development of an alloy system, high-speed steel, is used as an example of the progress of physical metallurgy. Tracing the history of men and their thoughts as they studied and invented and modified these materials, the story of high-speed steel since the 1890&apos;s is seen to be a long, slow, but steady progression of achievements. Today&apos;s multiplicity of high-speed steels are the result. Data are presented on quantitative metallography of carbides in high-speed steel with high vanadium content using the QTM instrument. Grindability as well as mechanical properties are related to the content of excess MC and M6C carbides in a series of high-speed steels and the newer matrix steels. These emphasize the present state of knowledge and show the current stages of thought that may affect the development in succeeding years. It is a great thrill for me, an ex-research metallurgist and ex-practicing metallurgical engineer, to speak to an audience currently engaged in both pursuits on the occasion of the 43rd Howe Memorial Lecture before the Iron and Steel Division of the AIME. I shall not review Henry Marion Howe&apos;s distinguished career, so adequately reviewed in Maxwell Gensamer&apos;s contribution in the 1965 AIME History of Metallurgy, except to point out that, while leading the life of an intellectual, he worked as a practicing research metallurgist and a practicing metallurgical engineer for significant periods of time and contributed greatly in both areas. For those of you who believe, as I do, that in the intellectual activity of metallurgy we are blessed with an intimate mixture of science and engineering (see Mehl&apos;s 1960 Howe Lecture), we might recall that Howe, while pursuing a life of writing and teaching in later years, served as the first Chairman of the Division of Engineering of the National Academy of Sciences. That metallurgists were called upon then to lead an engineering recognition movement is perhaps related to the strong part played by the AIME and its members in the recent establishment of a National Academy of Engineering and to the fact that a metallurgist is its head, 47 years after Howe served. I stress these engineering aspects for I wish to talk about a metallurgical engineering subject today. Alloy systems, physical metallurgy, and steel blended with an historical perspective and a report on new techniques to improve the old will, I trust, be of sufficient interest to bring these lectures back to the physical-metallurgy banner from which they have departed for 4 years. Those process metallurgists, open-hearth fiends, and physical chemists among you will just have to be patient. The development of an alloy system is the engineering application of scientific thought and fact. There are many interesting alloy systems, developed to a high degree of technology and sophistication over the past 40 to 70 years. These systems are bound together and related by a similar set of characteristics. For example, stainless steels are a system in which the members are related by a high chromium content which gives a corrosion-resistant characteristic. A subfamily in this system would be austenitic steels

Jan 1, 1967

By John Philip Zannaras

John Philip Zannaras (Registered Professional Engineer, Congress, Ariz.)- The authors show in their [Fig. 4] the cumulative results of grinding with two sizes of bails, one 30 mm and the other 20 mm. The Gaudin-Meloy probability for breakage for a single fall used by the authors in their paper is given by their [Eq. 6]. Another form of [Eq. 6] is given by Gaudin-Meloy in their paper as follows: [ ] From the definition of A given by Gaudin-Meloy it is obvious that A30 is greater than A., it therefore follows from the foregoing equation that according to the Gaudin-Meloy formula the probability of breakage for a single fall of all the balls in the 20-mm experiment was more than 2.25 times the probability of breakage in a single fall of all the 30-mm balls which is contradicted by the authors&apos; experimental evidence in [Fig. 4] in which is shown that much more grinding took place with the 30-mm balls. In fact the authors present convincing evidence that the Gaudin-Meloy work is erroneous because their work is based only on a geometric configuration and on ambiguous and uncertain definition of A and disregards the fact that the distribution of fracture depends on other important and indispensable factors including the intensity of stress caused on the feed grain by the balls. That there is an immense and chaotic variation of stresses caused on the feed grains by the balls is shown by a formula, derived by this writer and published in 1955. The derivation of this formula is given in the Appendix of this discussion; it contains the variables in the operation of ball mills and is based on the science of mechanics-not on probabilities. [ ] where T is the unit stress in pounds per square inch produced by the moving load, h is the height in feet through which P has fallen, E is the modulus of elasticity of the rock, P is weight of one ball, and L is the size of the grain (assumed to be a cube of side L). It will be shown by this writer&apos;s formula that when a 30-mm ball strikes any size of feed grain it will cause 1.837 times higher stress than the 20-mm ball when striking the same size grain. It will be shown that when the 30-mm ball or the 20-mm ball strikes a feed grain of 0.1 mm it will cause 90 times more stress on the grain than when it strikes a 2-mm grain.

Jan 1, 1974

By R. R. Seeber

(Pittsburg Meeting, March, 1910.) IN the copper-mining district of northern Michigan a fair-sized mine usually operates two or more shafts along the strike of the lode, these shafts being usually at least 1,000 ft. apart. The tonnage to be hoisted from each shaft is large-from 13,000 to 25,000 tons per month. The hoisting-engines used are generally steam-driven, non-condensing, duplex engines with Corliss valves, supplied by steam from separate boiler-plants where the distance between shafts is great. In an attempt to centralize power-plants and secure central-station economies, the Winona Copper Co. installed an electric hoist of the Ilgner type, with Ward Leonard control. A brief description of this plant has already been published.1 The only point of variation from the simple Ilgner set lies in the connection of two generators to a single induction-motor by flexible couplings. These generators serve motors which operate hoisting-drums at separate shafts, viz., No. 4 shaft, Winona, and No. 1 shaft, King Philip. , The hoist for No. 4 shaft, is about 1,700 ft. from the power-plant, and in this building the motor-generator set is placed. No. 1 King Philip hoist is 1,500 ft. from the motor-generator set. The equipment of the motor-generator set is as follows: In the middle of the set is a 12-pole, 450-h-p., 600-rev. per min., 2,080-volt, three-phase, 60-cycle, variable-speed induction-motor, connected on each side to a 20-ton fly-wheel which is 10 ft. in diameter, and to a 6-pole, 170-kw, 575-volt, interpole, direct-current generator. On each side of the shaft is placed a separate exciter, which delivers current at 125 volts. The lubrication of the four main bearings that support the fly-wheels * Presented also, by mutual agreement, at the meeting of the American Institute of Electrical Engineers, New York, N. Y., Mar. 11, 1910. Engineering and Mining Journal, vol. lxxxviii., No. 3, p. 110 (July 17, 1909).

Sep 1, 1910

By F. S. Norcross

DEVELOPMENT of the manganese deposits of Cuba is a matter of importance not only to those involved in this industry on the Island but to the United States steel industry and to our Nation as a whole. For years our domestic resources of manganese have been wholly inadequate, but the recent Cuban development points the way toward solution of this strategic mineral problem.

Jan 1, 1939

By S. LeFevre

, The solution of the housing and sanitation problem in mining communities, keeping in view both economic and humanitarian aspects, demands the best thought of the management of such enterprises. Upon the solution depend the health and comfort of the employee and his family, and as a consequence his contentment and efficiency. The following description covcrs briefly the methods installed for Witherbee, Sherman & Co. The operation of the system has been for about two years under the direct supervision of T. A. Hammond, Land Agent, and I am indebted to him for a compilation of the results. Sanitation The sanitary service covers 238 tenements. The installation cost was about $22 per tenement, as follows: Privy, $15; privy box, $3; proportion of incinerator cost, $2; garbage can, $2. The operating cost is $1 per month for each tenement. In considering the installation of an ordinary village system of water supply and sewerage two difficulties were encountered: First, lack of a sufficient quantity of water; there is no stream large enough, as Mineville is situated very close to the divide between the Lake Champlain and Hudson River watersheds. A storage reservoir was tried, but the only location available, among glacial hills, would not hold water. Second, the expense of digging ditches for the distribution of water and sewer pipes is so great as to be prohibitive; Mineville is built chiefly in a valley covered in the bottom with drift, in this case a combination of boulders and hard pan. Digging in this material costs 80c. to $1 per cubic yard, and pipes must be placed 41/2 ft. down to be below frost. The houses are scattered along 4 miles of streets, the oldest having been built in the original forest 65 years ago. The newer houses have gone up a few at a time wherevcr a clear space could be found and the slopes were not too steep. This has advantages, as it separates the dwellings into

Jan 1, 1915

By W. A. Anderson

Recrystallization of cold-worked metals has long been known to proceed by a process of nucleation and growth.&apos; When a cold-worked metal is heated to a temperature at which recrystallization will ensue, nuclei of new grains, essentially strain-free, appear and grow. As the process proceeds, nuclei continue to appear and to grow, until the cold-worked matrix has been entirely consumed and recrystallization has been completed (Fig. I). Conducted isothermally, a measurement of the fraction of the matrix recrystallized plotted against time, yields an isothermal recrystallization curve, showing the time course of the recrystallization process (Fig. 2).2 Evidently, then, the rate of recrystallization is determined by the rate at which nuclei form and the rate at which they grow. The rate of nucleation N is the number of nuclei that form in unit time in unit volume of the unrecrystallized matrix, and the rate of growth G is the increase in radius of the recrystallized grain per unit time. In recent years attempts have been made to determine N and G as these vary with the well-recognized variables affecting recrystallization: time, temperature, degree of deformation, etc.1 Such studies yield information that is more fundamental than that conveyed by the conventional recrystallization diagram,&apos; since the rate of recrvstallization is thus analyzed into its two component rates3 Methods are now available by which N and G can be measured, and analytical expressions have been developed for the interrelationships among N, G, the isothermal recrystallization curve, and the final grain size, which greatly facilitate analysis.2-4 The application of these methods has been demonstrated recently for the recrystallization of silicon ferrite.2 Data on N and G in dependence upon the recognized recrystallization variables are, however, very fragmentary;" values of N and G have been determined for some metals, but the effect of temperature, which would yield the fundamentally important activation energies, has been too little studied. Thus far there has been no detailed study of the recrystallization of any one metal in terms of X and G ovcr appreciable ranges of the variables time, temperature, degree of deformation, and original grain size. It is the purpose of the present paper to provide such a study, employing aluminum.

Jan 1, 1945

By E. G. SINCLAIR

DRILLING wildcat wells in Wyoming differs a little from methods used in any other field. Here it is always advisable to start the hole as large as is convenient in order to carry each string of pipe as far as possible, so that drilling can be continued a thousand feet deeper if necessary, as there is always sand a few hundred feet ahead that really ought to be tested. This plan may seem ambitious, but if it is adhered to, it will save a great deal of trouble before the well is completed. In making the location, one representative from the operating department and one from the geological department should work together, so that the well may be in the best possible place for obtaining oil and the most feasible place to drill for the operating department. In Wyoming nearly all wells are drilled with standard tools, as with them a better log can be kept and better time made in completing the hole. The shales of Wyoming are very hard and do not mix well in a wet hole. The shale cuts into large pieces, too large to be circulated out of the hole, and forms a mat on the rotary which soon cuts off circulation. Then if this mat cannot be jarred from the bit, the drilling string has to be pulled and the mat cut off from the bit with a pick or an axe. I have seen standard tools come out of a wet hole with 10 to 16 in. of mat on the bottom of the bit. Rotary tools have drilled wells satisfactorily in the Big Muddy field and at Billy Creek, but in the other fields the wells have been drilled much more economically with cable tools.

Jan 1, 1926

By Francois E. Heuze

INTRODUCTION Rock slope stability typically is governed by the geological discontinuities. This stability can be improved by drainage, unloading, adjustment in slope orientation, adjustment in slope angle, and also by reinforcement such as bolts or tendons. This paper addresses the modeling of bolt reinforcement in rock slopes. Most geological discontinuities such as joints have rough surfaces; they dilate during shear displacement. Their shear strength is characterized by two envelopes (Fig. 1); the peak envelope is distinct from the residual envelope when the joints can dilate. If the dilation is restrained transversely, such as with bolts, the normal stress will increase and the joint strength also will increase. It has been demonstrated that this increase may be considerable (Obert et al., 1976). The new normal stress at peak strength is a com- posite function of the properties of the rock mass and of the steel (Heuze, 1979). Hence, the dilation and its resultant effects on joint shear strength must be included in the analysis and design of the reinforcement. We present a model which can be used to perform such an analysis. Early studies of rock reinforcement in mining and civil applications (Lang, 1957 - Panek, 1962 - Osen and Parsons, 1966 - Lang, 19721, did not consider the specific effects of bolts on joint shear strength. In 1973, Heuze and Goodman reported direct shear tests on rough sandstone joints with bolts perpendicular to the joint plane (Fig. 2). The peak shear strength of such joints was greatly in excess of the shear strength of the unbolted joints. The excess

Jan 1, 1983

By T. D. Thomas

CONTENTS PAGE T. D. Thomas-Misfires in Anthracite Coal Mines 3 W. H. Forbes-Misfires in Bituminous Coal Mines 12 A. W. Worthington-Misfires in Non-metallic Mining (Limestone) 18 Misfires in Anthracite Coal Mines BY T. D. THOMAS, * LANSFORD, PA. (New York Meeting, February, 1929) IN THIS paper, major attention is given to misfires in mines where electric multiple shot-firing is the system used. Misfires are sometimes caused by one action or condition and at other times by a combination of two or more. They may be divided into two classes: (1) those caused by workers in the mines, (2) mechanical or manufacturer&apos;s causes. The second cause will be discussed first.

Jan 1, 1929

By James A. Crookston, William D. Fitzpatrick

Committee C-8 of the American Society for Testing and Materials defines "Refractories" as "Material, usually nonmetallic, used to withstand high temperature," and it defines the term "Refractoriness" thus, "In refractories the capability of maintaining the desired degree of chemical and physical identity at high temperatures and in the environment and conditions of use." The ability to withstand high temperatures is critical to classifying a material as a "refractory." However, as the foregoing definition of "refractoriness" implies, the refractory material may be subjected to and is expected to resist not only high temperatures but a variety of other destructive forces incident to its use. These include abrasion, impact, thermal shock, chemical attack, and high level loads at high temperatures. The various industrial applications of refractories represent an infinite variety of combinations and degrees of severity of these destructive forces, including high temperatures. Naturally, such a variety of application conditions leads to a need for a wide variety of refractory products to satisfy those conditions. The number of refractory products available is great enough that some form of classification is necessary to a discussion of refractories. Refractories may be classified in several ways, but the most suitable one is based on their general compositions and to lesser degrees on their physical condition and distinctive properties. The primary types of brick include aluminosilicate brick (fire clay and alumina), basic brick (magnesia and chrome ore, alone and in various combinations), silica brick, insulating brick, and special refractories (carbon, Sic, ZrO,, zircon, borides, and nitrides). Brick are, of course, preformed and are usually heat treated at high temperatures before use, but are in some instances unburned and/or chemically bonded, including the relatively new class of tar-bonded magnesia and/or dolomite brick. In addition to preformed refractories, another broad category includes the so-called specialty refractories, which are usually made in the same types as itemized for brick-bonding mortars and high temperature cements, hydraulic setting castables or refractory concrete, plastic firebrick, and ramming mixes. Refractory grains, such as fire clay and high alumina calcines, dead-burned magnesite and periclase, and dead-burned dolomite are also considered refractory products. Brick are also classified on the basis of physical dimensions, as standard sizes and special shapes. The standard sizes are those which are of definite shape and design and are designated as 9 x 4 ½ x 2 ½ in. and 9 x 4 ½ x 3 in. straights and series. All other brick of non- standard sizes are referred to as special shapes. These come about as a result of a particular need for a given furnace or for a particular application.

Jan 1, 1975

By Thomas W. Dawson

The H. C. Frick Coke Co. has used belt conveyers for handling coal for the last eighteen years but, until recently, only for small tonnages and over short distances. The first installations were outside the mines for distributing coal to various parts of plants. A belt conveyer was put in service at Colonial No. 4 Mine in November, 1906, to carry coal from the main hoisting shaft to a storage bin serving two blocks of beehive ovens on the other side of the valley; it was in constant service until the Colonial No. 4 ovens were abandoned less than a year ago. This conveyor was in an overhead gallery that spanned our sidings and yard tracks and the main line of the Pennsylvania Railroad. It was a crude installation, from the viewpoint of present conveyor engineering practice. It had no mechanical feeding device, the coal simply ran through a gate in the side of a bin on to the belt; but one belt on this conveyor lasted eleven years. This conveyor is about 300 ft. long center to center of pulleys. It operated at a speed of 250 ft. &apos;per min-and carried about 400 tons per day. On this basis, the belt life of eleven years means that not over a million and a quarter tons was carried by the belt. whi1e: this is not a large tonnage, the cost per ton was much less than by any previous method in use for supplying coal to ovens located at a distance from the main shaft. The next belt conveyor was installed at Bridgeport Mine in 1907. It carried about the same daily tonnage as the first, delivering from the hoisting shaft to a coke-oven bin. Very few data were kept on this conveyor. It also operated until the coke ovens at the plant were put out of blast and the coal taken to the Clairton byproduct plant by river. In 1916, work was started to equip the Bridgeport, Palmer, Gates, and Ronco mines to load their entire output on the river for transportation to the Clairton byproduct plant, which was then being built. These mines were all operating at that time and had a large area of coal available for river shipment. The Monongahela Railroad was located between the hoisting shaft and the river at each of these plants and, therefore, had to be crossed at each location to deliver coal to the river. After careful study, it was decided to transport this coal from the hoisting shaft to the river at each of these plants by belt conveyors.

Jan 1, 1925

By A. U. Seybol

Eight binary iron alloys were examined after ion nitriding experiments to determine the behavior of the following elements: Al, Mo, Mn, Si, Ti, V,Cr, and C. Only Al, Cr, Ti, and V additions caused hardening in binary iron alloys. A few steels were examined to see the effect of Cr, Cr + Al, Cr + Ti, and Cr + V. It is suggested that a useful new class of ni-triding grade steels might be those containing about I pct V. The nitriding of steel, first described by Fry1 about 45 years ago, rapidly attained commercial application with very little knowledge of the fundamentals involved. While Fry,&apos; in describing the status of nitriding in 1932, apparently correctly postulated hardening by precipitated nitrides, the details of the nitriding process were not understood, nor has the situation changed much since that time. It is also interesting to note that the compositions of some typical nitriding steels given by Fry at that time have changed little in the intervening years. Currently used nitriding steels owe their surface hardening to either chromium (as in 4340 steel) or aluminum plus chromium as in the Nitralloy grades, where both CrN and AlN appear to contribute to harden ing. Titanium additions have been studied experimentally, but thus far titanium steels have not won wide commercial acceptance. This subject will be expanded later. The orthodox ammonia nitriding process has been reviewed very adequately many times as in Jenkins3 and Case and VanHorn,4 and their is no need to outline the process here. Ion nitriding is not as well-known, although there have been several descriptions5-9 of the process given, sometimes with comparisons with the ammonia process. Most of these papers are primarily concerned with a description of the equipment, or of the physics or electrical engineering aspects of ion nitriding, but Noren and Kindbom9 gave the results of a metallurgical investigation using both processes. In brief, ion nitriding is carried out in a vacuum chamber from which the air is exhausted and replaced by a N2-H2 mixture, typically containing 10 to 20 pct N2, at about 5 to 10 torr pressure. While ammonia gas has also been used in ion nitriding, there is no evidence that ammonia makes any improvement in the ion nitriding process. A few hundred volts dc is applied between the grounded container wall (positive) and an insulated center post supporting the work (negative) to be nitrided. A glow discharge is created in the ionized gas, accelerating positive nitrogen ions to the work. These ions contain enough energy to form the normally unstable Fe4N "white layer", thus establish- ing surface nitrogen solubility characteristic of the a Fe/Fe4N equilibrium. This creates a substantial concentration gradient, driving dissolved nitrogen into the steel. The temperature employed is in the same range (around 500" to 550°C) as in ammonia nitriding, but because of factors which are not understood at present the nitriding time is ordinarily considerably reduced in ion nitriding. Other advantages have been cited,9 but it is not the purpose of the present work to contrast the two processes. The present objective was to examine the behavior of binary iron alloys during ion nitriding with respect to the microstructure, hardness level, and depth, and to examine some of these factors in steels as well. In this way it was hoped to be able to find out something about the individual role of these elements in steels. While all the work was done by ion nitriding, there seems to be no reason why any conclusions reached would not equally apply to ammonia nitriding, excepting only the kinetic aspects of the process. Another objective was an exploration of the critical-ity of the ion nitriding variables: gas composition, pressure, temperature, and time. EQUIPMENT AND MATERIALS The equipment used was substantially as described by Jones and Martin.8 The vacuum tank was about 12 in. in diam by about 18 in. high, and consisted of water-cooled stainless steel, with a single small window at the top for viewing inside. This sat on a heavy mild steel base equipped with the main pumping port, pressure control port, and vacuum gaging. A series of variable resistances was interposed between the glow discharge and a large-capacity -40 amp variable primary transformer feeding a 1000-v transformer, but 600 v were about the maximum ordinarily used. With the small l-in.-round, 4-in.-thick discs used for nitriding, the electrical load was usually about 500 v at 0.8 amp. The specimen temperature was controlled by a stainless-steel sheathed chromel-alumel couple, whose junction was in the steel stool upon which the flat discs were placed. These were ground through 400 Sic paper. Cycling of the temperature controller caused -0.2 amp variation in ion current, providing an ample control band. The binary iron alloys were made from vacuum-melted hydrogen-deoxidized electrolytic iron and alloys of 99.9 pct purity. Cast ll-lb-square tapered ingots were forged and hot-rolled to about 11/4-in.-diam rounds. Discs of 1/4 in. thickness by about 1 in. diam were machined from the rods for nitriding specimens. The following alloys were prepared: 1 pct each of Mn, Mo, Cr, Ti, Al, V, Si, and an Fe-0.8 pct C alloy. EXPERIMENTAL VARIABLES Of the variables total gas pressure, nitrogen partial pressure, temperature, and time, only nitrogen partial pressure was found to be critical to the operation. A critical nitrogen partial pressure was found corre-

Jan 1, 1970