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By Richard W. Lodge

Ix the crucible-method of assaying ores for silver a certain amount of litharge is essential to supply sufficient lead to collect the precious metals. The object of this paper is to point out that the use of a .large excess of litharge in the assay of some ores will give results for silver that are uneven as well as low. So far as I know, however, an excess of litharge does not affect the results obtained in the crucible-assay of ores for gold. The main reasons for using, in the crucible-assay, much more litharge than is required to give the necessary lead button are : 1, its action as a flux; 2, its action as a desulphurizer; and 3, its action as an oxidizer, especially on metals like copper and nickel, whereby they are forced into the slag as oxides and thus prevented from passing into the lead button. Hence, by the use of much litharge in the crucible-assay more-ore can often be taken than in the scorification-process, and a lead button obtained which can possibly be cupelled at once or after a single scorification. The method is specially advantageous with an ore carrying much copper or similar impurity and poor in silver, when the assayer does not wish to resort to a wet-analysis for the determination of the silver. It is well known that some ores give better results when assayed by the scorification-method, while others give better results by the crucible-method. For several years I have noticed that, when much litharge was used with certain sulphide and arsenical ores, the results were considerably lower than when the scorification-method was used. This fact was more forcibly brought out in connection with certain work carried on this year by Messrs. H. A. Frame and

Sep 1, 1907

By D. L. McDanels, J. W. Weeton, R. W. Jech

An investigation was conducted to determine the stress-strain behavior and tensile properties of metallic composites and to relate them to the properties of the base materials. Tungsten fibers in a copper matrix were chosen as the model sys-tem to investigate these properties. Room-temp-atzcre tensile and dynamic -modulus tests were used To meet the demand for improved structural materials, considerable effort is being directed toward the creation of composite materials. One such material under investigation is the fiber-reinforced composite, in which a ductile, relatively weak matrix is reinforced with high-strength fibers. Some work has been done on the reinforcement of metallic matrices with metallic fibers1"5 as well as with ceramic-whisker reinforcement. Summaries of much of this work have been published by Mach-lin7 and Baske~.' Work done at the Lewis Research Center of NASA-" has involved the making and testing of composites composed of a fiber, tungsten, and a matrix, copper, which were insoluble in each other. An equation was presented that showed the relation between the ultimate tensile strength of the composites and the strengths and relative volume percents of the components. This relation was verified experimentally for composites containing fibers extending the full length of the specimen as well as for composites reinforced with short-length or discontinuous fibers. Since the publication of the preliminary results,9'10 additional data have been obtained. This paper presents these data as well as analyses of the stress-strain behavior and the mechanics of deformation of uni-axially oriented, fiber-reinforced metallic composites, in which both components are mutually insoluble. EXPERIMENTAL PROCEDURE Composites were made with high-purity copper as the matrix and 3-, 5-, and 7-mil-diam tungsten wire as the reinforcing fiber. Some specimens were made in which the reinforcing fiber extended completely through the full length of the composite test section. The fibers were placed in ceramic to determine these properties. The composites were reinforced with either continuous or discontinuos tungsten fibers. The tensile properties and stress-strain behavior of composites reinforced with either type of reinforcement were similar, and in both cases the full strength of the fiber was utilized. tubes to insure axial orientation and infiltrated with copper at 2200°F for 1 hr. Composites were also made with short-length (3/8 in. long) 5-mil-diam tungsten fibers as discontinuous reinforcement and infiltrated under the same conditions. The reinforcing fibers in both cases were longitudinally oriented in the direction parallel to the tensile axis. Room-temperature tensile tests were conducted on the composites, stress-strain curves were obtained, and ultimate tensile strength and elongation were measured. Dynamic modulus of elasticity, based upon the resonant frequency induced in the flexural mode of vibration, was also determined for the composites and the components. A more detailed discussion of the experimental procedure employed in this investigation may be found in Ref. 11. RESULTS Room-temperature tensile tests were conducted on 3-, 5-, and 7-mil-diam tungsten wires which had been annealed for 1 hr at 2200°F and show the tensile strength of the wires to be 331,000, 327,000, and 290,000 psi, respectively. Since all the composites were infiltrated under these conditions, the strengths were considered to represent the strength of the fibers in the composites throughout this study. The average tensile strength of the annealed copper used as the matrix in this investigation was 27,800 psi. Results of room-temperature tensile tests on composites reinforced with 3-, 5-, or 7-mil-diam tungsten fibers are plotted as functions of composition in Fig. 1. These data represent previously reported datag,l0 as well as data more recently obtained. The line shown on each curve represents a prediction of tensile strength as a function of composition; the calculation of this line was explained in Refs. 9 and 10. A similar plot is presented in Fig. l(d) for composites reinforced with short-length, discontinuous 5-mil-diam tungsten fibers. Again, both the previously reported and the recent data are presented, and the line shown is identical to that shown for

Jan 1, 1965

By Robert F. Mehl

PROGRESS in the general field of nonferrous physical metallurgy during the past .year has been uneventful but healthy. A continued increase is apparent in the number of useful alloys and in the mechanical treatment and heat- treatment of finished metals and alloys nothing can hinder the multiplication of alloys or the diversification of their treatment as knowledge of the behavior of .alloys increases; as ternary and quaternary alloys are better understood, hundreds of new metal combinations with unusual properties may well be expected. Evidence of rapid progress is already at hand.

Jan 1, 1936

By George Rice

THE A.I.M.E. Ground Movement and Subsidence Committee, pro-posed in 1920, held its first technical meeting in February 1923, under the able chairmanship of Mr. H. G. Moulton. The following list of papers and discussions, indicating the scope of the problems and relation to various conditions and method of mining, were given at that meeting by the distinguished mining engineers: J. Parke Channing, on Subsidence at Miami, Arizona; Howard N. Eavenson, on Mining an Upper Bitu-minous Seam after a Lower Seam Has Been Extracted; J. J. Rutledge, on Subsidence in Two Oklahoma Coal Mines; Benjamin F. Tillson, on Caving Cracks at the Franklin Mine, New Jersey; Dr. F. W. McNair, on the Dome Theory; William Kelly, on disadvantageous effects in Mining and Back-filling Working Upward a Steep-Pitching Iron-ore Bed; Eli T. Conner, on the good results of Back-Filling by Hydraulic Means in Preventing Destructive Subsidence in the Anthracite District; Thomas H. Claggett, on the merit of Systematic Pillar Drawing in Preventing Cracks in an Upper Seam; Henry H. Otto, successful results in the anthracite district in Mining Lower Seams before Upper Seams; Douglas Bunting, on Leading Factors Incident to Successful Mining of an Overlying Seam; Edwin Ludlow, on there being "less damage to buildings when there was complete removal of coal with complete packing than when room and pillar is used without extracting the pillars"; Edward O'Toole on "bumps" in eastern Kentucky mines, which he thought were the result of geologic stresses: H. A. Buehler, on Upheaval of Surface in an Illinois Case in Advance of the Face; and R. Dawson Hall, on The Mechanics of Subsidence from Mining. The author of this paper discussed various kinds of problems of ground movement and subsidence in both metal mining and coal mining; the production of great landslides by workings near an outcrop, as at Turtle Mountain, Alberta, Canada; and general

Jan 1, 1939

By J. T. Lapsley, I. I. Cornet, A. E. Flanigan, R. Hultgren, J. E. Dorn

WITH the greatly expanding use of magnesium during the war, it appeared necessary to the War Metallurgy Committee that procedures of heat treating common magnesium casting alloys be investigated systematically. Accordingly, the National Defense Research Committee of the Office of Scientific Research and Development placed a research contract with the University of California, supervised by the War Metallurgy Committee. Research on the solution heat treatment and aging of magnesium alloy AZ92, (formerly ASTM No. 17; also known as Dowmetal C or AM260) which was done under "Restricted" Project NRC-21, in 1942-1943, and reported, in detail in a final report to the OSRD on September 3, 1943, is the basis of this paper, which has been released for publication by the OSRD. American experience with magnesium alloys prior to World War II was limited, although some of these alloys had been in commercial use since 1909. Requirements of the aircraft industry for light alloys made it imperative to understand and utilize the advantageous strength-weight properties of magnesium castings. Magnesium casting alloys are commonly solution heat treated to increase their ultimate tensile strength and ductility; this treatment may be followed by an age hardening at elevated temperatures, which raises the tensile yield strength but diminishes the ductility. In the present investigation, AZ92 was studied to determine the effects on properties of various solution heat treatment and aging schedules. The principles of heat treatment of magnesium alloys are the same as for other non-ferrous alloys. The alloy studied, AZ92, has a nominal composition of 9 pct aluminum, 2 pct zinc, and minor constituents. Fig I shows, by the projection of isothermal sections on the concentration plane, the solubility surface1 of the ternary magnesium-rich solid solutions as determined by X ray analysis. From this figure it may be seen that above approximately 375°C (707°F), AZ92 alloy is a single phase alloy at equilibrium; below this temperature the equilibrium condition is a. two phase alloy. The beta constituent which precipitates from the solid solution exerts a hardening effect. Because the zinc concentration is only 2 pct, and because of its solubility relations, AZ92 resembles a binary alloy of magnesium with aluminum. The solubility curve1 of Fig 2 shows how rapidly the solubility of the beta phase decreases with decreasing temperatures. Unlike many aluminum alloys, magnesium alloys do not age harden at room temperatures; precipitation hardening of AZ92 alloy is performed at about 177°C (350°F). At this temperature about 3 pct aluminum

Jan 1, 1947

By Oliver Bowles

A HEAVY gel of bentonite clay has been proposed as an effective lubricant to speed down the ways to sea, river, or lake, the mighty cargo ships now hitting the water at the rate of about three a day. Another unusual application of a nonmetallic mineral is in food conservation, for the claim has been made that the next new item on the menu for poultry and rabbits will be vitamin tablets prepared from mont-morillonite clay. These uses have minor importance but illustrate not only the diversity in utilization, but the notable trend in 1942 toward mobilizing nonmetallic minerals for the war program. Although occupying less headline space than iron, steel, copper, aluminum, magnesium, and other metals, the nonmetallics are filling important emergency needs. Mica and quartz crystal are essential to communication; asbestos is urgently needed in fireproof heat and electrical insulation; and strontium minerals are utilized in the manufacture of signal flares and tracer bullets.

Jan 1, 1943

By P. K. Koh, H. A. Lewis, H. F. Graff

New data on the distribution of silicon between slag and carbon-saturated iron at 1600Oand 1700OC are presented which, in combination with previously published data, permit the determination of silica activities over a broad range of compositions in the CaO-Al2O3-SiO2 system. The distribution of silicon between graphite-saturated Fe-Si-C alloys and blast furnace-type slags in equilibrium with CO has been described in previous publications.1"3 In this past work the silica-silicon relation was established at temperatures of 1425" to 1'700°C for slags containing up to 20 pct A12O3. This paper presents the results of additional studies at 1600" and 1700° C which extend the silicon distribution data at these temperatures for CaO-A12O3-SiO, slags over a range from zero pct Al2O3 to saturation with Al2O3, or CaO.2Al2O3. The upper limit of SiO2 is set by the occurrence of Sic as a stable phase when the metal contains 23.0 or 23.7 pct Si at 1600" or 1700°C, respectively. The activity of silica over the expanded range is determined directly from the distribution data.3 Recently4-7 other investigators have studied the activities of SiO, and CaO, principally in the binary system, using different methods and obtaining somewhat different results. EXPERIMENTAL STUDY The experimental apparatus and procedure have been fully described in previous publications.1, 3 Six new series of experimental heats have been made, four at 1600° and two at 1700°C. Master slags of several fixed CaO/Al203 ratios were pre-melted in graphite crucibles, and these were used with additions of silica to prepare the initial slag for each experiment. Slag and metal were stirred at 100 rpm and CO was passed through the furnace at 150 cc per min. The initial sample was taken 1 hr after addition of slag at 1600°C or 1/2 hr after addition at 1700°C. The run was normally continued for 8 hr at 1600°C or 7 hr at 1700°C, and the final sample was taken at the end of this period. Changes in Si and SiO2 content indicate the direction of approach to equilibrium, and in a series of runs where the approach is from both sides this permits approximate location of the equilibrium line. Fig. 1 shows the results of such a series of 15 runs at 1600°C for slags of CaO/Al,O3 = 1.50 by weight. Figs. 2 and 3 record other series at 1600°C and Fig. 5 a series at 1700°C with fixed CaO/Al0 ratios. The results of the experiments at 162003°C have been reported in part in a preliminary note.3 In the experiments recorded in Figs. 4 and 6, the slags were saturated with A12O3 (or with CaO.2A12O3 within its field of stability) by suspending a pure alumina tube in the melt during the course of the run. The final slag analyses were used to establish the liquidus boundaries8 in the stability fields of CaO.2Al2O3 and of Al20,. ACTIVITY OF SILICA The free-energy change in the reaction has been calculated by Fulton and chipman2 from recent and trustworthy data including heats of formation, entropies, and heat capacities. The more recent determination by Olette of the high-temperature enthalpy of liquid silicon is in satisfactory agreement with the values used and therefore requires no revision of the result which is expressed in the equation: SiO2 (crist) + 2C (graph) = Si + 2CO(g.) [1] &F° = + 161,500 - 87.4T The standard state for silica is taken as pure cristobalite and that of Si as the pure liquid metal. Since the melts were made under 1 atm of CO and were graphite-saturated, the equilibrium constant for Eq. [I] reduces to K1 = asi /asio2. The value of this constant is 1.77 at 1600°C and 16.2 at 1700°C. Through K1, the activity of silica in the slag is directly related to the activity of silicon in the equilibrium metal.

Jan 1, 1960

By Milo W. Krejci

(Butte Meeting, August, 1913.) THE plant and quarries of the Inland d Portland Cement Co.. are located- at Metaline Falls, Wash, about 128 miles north of Spokane, on the Fend Oreille river, and 10 miles, of the Canadian border. The plant is one of a chain of cement plants controlled by the Lehigh Portland Cement Co., of Allentown, Pa. Work on this plant was commenced in June, 1910, and was completed in April, 1911, but on account of some delays in the construction of the power plant, the works were not put into operation until August., 1911. Since then it has been in continuous operation and has furnished the Inland Empire with a high grade of cement. Fig. 1 is a, view and Fig. 2 is a plan of the works. Water Power Development.-The source of the water supply for the hydro-electric plant of the Inland Portland Cement Co. is Sullivan lake, a body of water approximately 5.5 miles long and 0.5 mile wide, situated in the Kanisku Forest Reserve. A wooden crib dam was installed so as to raise the elevation of the lake 25 f and the additional storage capacity was taken up by the diversion of Sullivan creek into the lake by means of a wooden flume, 0.25 mile long, 6 by 8 ft. in crosssection, and a ditch 1,200 ft. long. The water from the lake follows the natural water course to an intermediate storage reservoir, which was created by the construction of an earthen dam. This pond was used in connection with the saw mill which was installed at this point. Besides the earth dam, there was also built a crib, at the point shown in the sketch map, Fig. 3. This crib dam is 35 ft. high. From this point the excess water follows the natural -course of Sullivan creek to the Pend Oreille river.

Jan 7, 1913

United Engineering Trustees, Inc. W. D. B. MOTTER, JR., '40 A. L. QUENEAU, '41 ALBERT ROBERTS, '39 The Engineering Foundation GEORGE D. BARRON, '40 F. F. COLCORD, '3S A. L. QUENEAU, '38

Jan 1, 1938

By R. C. Ferguson, Harlowe Hardinge

Oscar Johnson—In my opinion, the effect of mill speeds on grinding costs must be studied along with capital investment and dollars gathered together as profits. Comparing the entire groups of operators with those who have had the opportunity to make slow-speed mill studies, I think you will find the latter small in numbers. Most managers want the equipment worked to its maximum output. There are, however, some installations where plant and mill sizes are such that they can do the job with reduction of mill barrel speeds. The past and the present installations of the industry are laid out to get the most capacity for the least capital outlay. This is the case even with the plants of Chile Exploration, International Nickel, Morocco, and Anaconda, now under construction or being changed. The industry recognizes that most all equipment it buys today is good and can be depended upon for efficient performance. Under this scheme of things, I am doubtful that slow-speed ball mill operation will be generally applicable. With reference to the U. S. Bureau of Mines laboratory tests, I think table II could have been omitted. It is inconclusive as to maximum efficiency for the low-pulp level mill on hard ore. There should be no question about this point. However, data on mill speeds can be found to substantiate various theories as well as refute them. Gow, Guggenheim, Campbell and Coghill, in their paper on Ball Milling,' believe their 2 x 2 ft laboratory mill reflects results that can be expected from large mills. If so, then referring to their table 11, they state, "The conclusion to be drawn from this second series is that high speed, not exceeding 72 pct of the critical, favors capacity, as before, but that with proper conditions of operation high speeds may give as good efficiency values as low speeds. In this case the efficiency values are nearly constant. A horizontal curve would indicate that the amount of grinding was directly proportional to the power expended, and these tests suggest that such a coildition can be made to exist in commercial operations." Table II (From Paper by Gow et a1)2 Speed. Pot Critical 32 42 52 62 72 82 Capacity: Surface tons per hr (65- mesh) 266 42.1 54.4 65.9 74.3 74.1 Surface tons per hr (200- mesh) 56.1 87.4 112.7 137.1 154.2 153.0 Efficiency: Surface tons per net hp hr (65-mesh) 35.7 36.3 36.3 35.4 34.3 32.3 Surface tons per net hp hr (200-mesh) 75.3 75.3 75.1 73.7 71.0 66.0 Ore in mill, 1.b. 98 100 100 113 122 165 The field performance data, table 111, represents much effort in its collection and preparation. But, one must realize that there are many variables that effect the efficiency of grinding mill operation, and too much must not be assumed as to the effect of some specific change. Possibly with changes in mill speed, the results might be more consistent by also a change in ball rationing, type of ball, volume of ball charge,. p.ulp level and amount of pulp in the mill, pulp consisting, design of liner, circulating load, etc. Also, changes in ore character must be reckoned with when evaluating grinding performance. At present the Climax Molybdenum Corp. is running at much reduced capacity. Mr. James Duggan informs me that at mill speeds of 17 rpm, they save a $0.025 per ton on liners and $0.025 per ton in power, but, if the demand for molybdenum increased, he would go back to higher speed to obtain maximum tonnage, as the values from the increased tonnage would far more than offset the one half saving at the slower speed. The Jnspiration ran a six months' test between mills running 21 rpm and 23.5 rpm. The slower mills ground 10 pct less ore with a slight saving per ton, but when the reduced plant tonnage was checked back into the actual cost figures of concentration, the high-speed mills with their greater tonnage showed considerable advantage. To be convinced of possible practical results from the predictions in the conclusions, I think we would have to rely on the analysis of expert cost accountants to furnish the necessary proof figures. Hardinge and Ferguson are to be commended for the work in preparing this paper. I am convinced that our Massco engineers should go into higher speeds with our equipment. Harlowe Hardinge (authors' reply)—For one, I heartily agree with Mr. Johnson's opening statement that the effect of mill speeds on grinding costs must be studied along with capital investment and dollars gathered together as profits. It was on this basis and for this reason the paper was written. Mr. Johnson, on the other hand, takes the position that, on the whole, low speeds are not justified from the economic standpoint, basing his principal reason on the fact that lower mill speeds cut mill capacities and hence reduce the gross income from the product produced. There is no denying this point. It is almost axiomatic. It is for this very reason that the overall advantage of lower mill speeds has been discounted and even overlooked. It was for this reason mainly that the paper was written in the first place. It is one thing to plan an efficient operation at the outset, basing one's figures on the tonnage requirements at the time, and it is quite another to be confronted with the problem of increasing the output of an existing installation at a minimum of capital expenditure. Economic consideration of a new installation is greatly influenced by referring to an old one. Too often, the analyst assumes that if this practice is followed in the new installation, one would not go wrong. It is just here that he may be wrong. Past practice and low capital expenditure are all too frequently given priority over the engineer's analysis of operating costs. When we are able to start fresh, we should give proper weight to other economic factors which do not exist in an old installation. It is these economic factors that make it possible to spend at the outset just a little more money and get it back in a matter of months and effect big savings for years to come. F. C. Bond—This paper is of considerable importance in that it emphasizes a modern trend to operate ball mills at somewhat slower speeds than formerly. We have checked the data in the paper with that obtained

Jan 1, 1951

By Harlowe Hardinge, R. C. Ferguson

Oscar Johnson—In my opinion, the effect of mill speeds on grinding costs must be studied along with capital investment and dollars gathered together as profits. Comparing the entire groups of operators with those who have had the opportunity to make slow-speed mill studies, I think you will find the latter small in numbers. Most managers want the equipment worked to its maximum output. There are, however, some installations where plant and mill sizes are such that they can do the job with reduction of mill barrel speeds. The past and the present installations of the industry are laid out to get the most capacity for the least capital outlay. This is the case even with the plants of Chile Exploration, International Nickel, Morocco, and Anaconda, now under construction or being changed. The industry recognizes that most all equipment it buys today is good and can be depended upon for efficient performance. Under this scheme of things, I am doubtful that slow-speed ball mill operation will be generally applicable. With reference to the U. S. Bureau of Mines laboratory tests, I think table II could have been omitted. It is inconclusive as to maximum efficiency for the low-pulp level mill on hard ore. There should be no question about this point. However, data on mill speeds can be found to substantiate various theories as well as refute them. Gow, Guggenheim, Campbell and Coghill, in their paper on Ball Milling,' believe their 2 x 2 ft laboratory mill reflects results that can be expected from large mills. If so, then referring to their table 11, they state, "The conclusion to be drawn from this second series is that high speed, not exceeding 72 pct of the critical, favors capacity, as before, but that with proper conditions of operation high speeds may give as good efficiency values as low speeds. In this case the efficiency values are nearly constant. A horizontal curve would indicate that the amount of grinding was directly proportional to the power expended, and these tests suggest that such a coildition can be made to exist in commercial operations." Table II (From Paper by Gow et a1)2 Speed. Pot Critical 32 42 52 62 72 82 Capacity: Surface tons per hr (65- mesh) 266 42.1 54.4 65.9 74.3 74.1 Surface tons per hr (200- mesh) 56.1 87.4 112.7 137.1 154.2 153.0 Efficiency: Surface tons per net hp hr (65-mesh) 35.7 36.3 36.3 35.4 34.3 32.3 Surface tons per net hp hr (200-mesh) 75.3 75.3 75.1 73.7 71.0 66.0 Ore in mill, 1.b. 98 100 100 113 122 165 The field performance data, table 111, represents much effort in its collection and preparation. But, one must realize that there are many variables that effect the efficiency of grinding mill operation, and too much must not be assumed as to the effect of some specific change. Possibly with changes in mill speed, the results might be more consistent by also a change in ball rationing, type of ball, volume of ball charge,. p.ulp level and amount of pulp in the mill, pulp consisting, design of liner, circulating load, etc. Also, changes in ore character must be reckoned with when evaluating grinding performance. At present the Climax Molybdenum Corp. is running at much reduced capacity. Mr. James Duggan informs me that at mill speeds of 17 rpm, they save a $0.025 per ton on liners and $0.025 per ton in power, but, if the demand for molybdenum increased, he would go back to higher speed to obtain maximum tonnage, as the values from the increased tonnage would far more than offset the one half saving at the slower speed. The Jnspiration ran a six months' test between mills running 21 rpm and 23.5 rpm. The slower mills ground 10 pct less ore with a slight saving per ton, but when the reduced plant tonnage was checked back into the actual cost figures of concentration, the high-speed mills with their greater tonnage showed considerable advantage. To be convinced of possible practical results from the predictions in the conclusions, I think we would have to rely on the analysis of expert cost accountants to furnish the necessary proof figures. Hardinge and Ferguson are to be commended for the work in preparing this paper. I am convinced that our Massco engineers should go into higher speeds with our equipment. Harlowe Hardinge (authors' reply)—For one, I heartily agree with Mr. Johnson's opening statement that the effect of mill speeds on grinding costs must be studied along with capital investment and dollars gathered together as profits. It was on this basis and for this reason the paper was written. Mr. Johnson, on the other hand, takes the position that, on the whole, low speeds are not justified from the economic standpoint, basing his principal reason on the fact that lower mill speeds cut mill capacities and hence reduce the gross income from the product produced. There is no denying this point. It is almost axiomatic. It is for this very reason that the overall advantage of lower mill speeds has been discounted and even overlooked. It was for this reason mainly that the paper was written in the first place. It is one thing to plan an efficient operation at the outset, basing one's figures on the tonnage requirements at the time, and it is quite another to be confronted with the problem of increasing the output of an existing installation at a minimum of capital expenditure. Economic consideration of a new installation is greatly influenced by referring to an old one. Too often, the analyst assumes that if this practice is followed in the new installation, one would not go wrong. It is just here that he may be wrong. Past practice and low capital expenditure are all too frequently given priority over the engineer's analysis of operating costs. When we are able to start fresh, we should give proper weight to other economic factors which do not exist in an old installation. It is these economic factors that make it possible to spend at the outset just a little more money and get it back in a matter of months and effect big savings for years to come. F. C. Bond—This paper is of considerable importance in that it emphasizes a modern trend to operate ball mills at somewhat slower speeds than formerly. We have checked the data in the paper with that obtained

Jan 1, 1951

By W. C. Hayes

The site selected for the United States prototype pumped storage project of Union Electric CO. was Proffit Mountain, five miles from Taum Sauk, the highest point in Missouri. Factors influencing final location were: high local relief; satisfactory rock type and structure; and an economic location in respect to existing transmission systems. The upper reservoir was constructed by excavating rhyolite porphyry from the crest of Proffit Mountain and constructing a rock fill dike encircling the area to form a 4350-acre foot reservoir. A 6564-ft tunnel connects the upper reservoir with the generating and pumping facilities. A concrete gravity dam on the East Fork of the Black River forms the 6350-acre foot lower reservoir. Precambrian rhyolite porphyry forms the crest of Proffit Mountain and the floor of the upper reservoir. The tunnel was excavated in rhyolite prophpy, granite porphyry, dolomite, shales and conglomerate. Abutments and the foundation of the gravity dam are in rhyolite porphyry, and much of the valley floor of the lower reservoir is underlain by dolomite and shale. Core drilling provided data on soundness of rock type, structure, depth of weathered zone and potential water loss in the fractured igneous rocks. After a six-year study of pumped storage and cost comparison with alternate stream generating units, the Taum Sauk pumped storage project was authorized by Union Electric Co. on Dec. 11, 1959.' The site selected is located in the St. Francois Mountains of southeast Missouri approximately 90 miles south of St. Louis (Fig. 1). The lower reservoir was provided by damming the East Fork of the Black River, a small tributary of the Black River with a minimum flow of about 1 sec ft. Construction of the upper reservoir was effected by quarrying the crest of Proffit Mountain - five miles from Taum Sauk Mountain, the highest point in Missouri — to provide material for a rock fill dike surrounding the quarried area. This provided a 55-acre mountain top lake with a water depth of 92 ft (Fig. 2). A vertical shaft and tunnel connect the upper and lower reservoirs through the two reversible pump-turbine motor-generator units operating under 800 ft of hydraulic head (Fig. 3). The output rating of the plant is 350,000 kw with daytime generation of about 2.2 million kw-hr under normal use. Night pumping will replenish water to the upper reservoir in about 91/2 hours3. The automatic operation is remotely controlled from the Osage plant and from the dispatchers office in St. Louis. GENERAL GEOLOGY Mountains of the St. Francois area consist of Precambrian granites, granite porphyries, extrusive fel-sites and basic dikes. Basal conglomerates overlain by Upper Cambrian Bonneterre dolomites and shales onlap the exhumed Precambrian knobs and hills and are exposed in the narrow valleys. Cambrian and Ordovician residuum as much as 200 ft thick is present on the slopes of many hills. Proffit Mountain consists of rhyolite porphyry and granite porphyry. All excavation for the upper reservoir was in rhyolite porphyry, and the same rock is present under the Bonneterre at the plant site and under alluvium at the lower reservoir dam site. The region has been dissected to the stage of early maturity with only small upland flats remaining. Considerable local relief (a requisite for the project) approaches 1000 ft. Streams flowing across the Precambrian ridges have formed restricted narrows, termed shut-ins. A shut-in approximately two miles downstream from the plant site provides an excellent site for the lower reservoir dam. TEST BORINGS Preliminary to final approval of the project, 12 test borings were made to determine subsurface geologic conditions (Fig. 2). Drill hole No. 12 at the lower reservoir dam site showed 20 ft of alluvium over solid rhyolite porphyry. Drill holes No. 1, 2 and 3 were drilled in the tail race area to depths of 66 ft, 75 ft and 95 ft respectively, and all bottomed in Bonneterre. Drill hole No. 4 at the plant site provided NX core to a total depth of 98 ft in Bonneterre. Drill

Jan 1, 1965

By George A. Miller

THE outstanding characteristic of the American business man is that he likes to run his own business his own way, without any interference from his wife, his friends, his bankers, and least of all from his government. The oil man, like the miner, is an American business man in which this special characteristic is even more pronounced. It may be because he has been an explorer and is more nearly like those pioneering Americans who explored, developed, and built these United States.

Jan 1, 1944

By J. W. Byrkit

Design features and operating methods at the new Ajo smelter are described in detail. Successful operation of a novel method of handling and charging wet concentrates to a deep bath type reverberatory furnace contribute to the daily production of 200 tons of anodes with good results from the standpoint of both metallurgy and economy. THE New Cornelia Branch of the Phelps Dodge Corp. is located at Ajo, Ariz. Large scale mining operations were started at Ajo in 1917, when a 5000 ton leaching plant was put in service to treat the copper carbonate ore that overlaid the sulphide ore-body. In 1924 a 5000 ton flotation plant was built to treat the sulphide ore and the leaching operation was abandoned a few years later. Changes in practice and additions to plant facilities have resulted in a gradual increase in the milling rate which now approaches 30,000 tons daily. Prior to the erection of the Ajo smelter, flotation concentrate was shipped by rail to Douglas, Ariz, where it was treated in the Phelps Dodge smelter. Construction of a one reverberatory furnace smelter to produce an average of about 200 tons per day of copper anodes at Ajo was started early in 1949. Initial heating of the reverberatory furnace was begun on June 21, 1950. Charging the furnace was started on july 8, and the first anodes were cast on July 14. Neither the anode furnace nor the reverberatory furnace has cooled since the initial firing. Fig. 1 is a photograph of the new smelter. Built primarily to eliminate the '300 mile haul of concentrate to the Douglas plant, the new smelter was designed to treat the Ajo concentrate, with a minimum of capital investment. A novel, and relatively simple, method of concentrate handling and furnace charging made unnecessary the installation and operation of expensive storage facilities and reclaiming equipment, and obviated the necessity of holding in storage large quantities of copper-bearing materials. (Patents are pending in the United States and abroad on the Ajo process.) In the selection and arrangement of equipment, consideration was given to the full utilization of all smelting facilities, reducing the amount of idle equipment to a minimum. The layout of the smelter is shown in Fig. 2. The important problem of internal transportation was minimized by arranging the reverberatory furnace, converters, and anode furnace in a compact group and providing storage bins inside the smelter building, within reach of overhead cranes, for fluxing materials and other supplies needed in the daily operation. This can be seen in the sectional view of the smelter given in Fig. 3. Incorporated in the design were many innovations in smelting equipment intended to facilitate operations and effect economies in maintenance expense and manpower requirements. Table I gives operating data of the entire plant. Metallurgy The metallurgical practice at Ajo is based essentially upon the use of a single, deep bath reverberatory furnace for smelting wet concentrate, without concentrate storage facilities. The large reservoir of slag and matte maintained in the furnace serves to equalize, to some extent, the day to day variations in the nature and grade of concentrate and permits

Jan 1, 1954

By George S. Rice

THE A.I.M.E. Ground Movement and Subsidence Committee, pro- posed in 1920, held its first technical meeting in February 1923, under the able chairmanship of Mr. H. G. Moulton. The following list of papers and discussions, indicating the scope of the problems and relation to various conditions and method of mining, were given at that meeting by the distinguished mining engineers: J. Parke Channing, on Subsidence at Miami, Arizona; Howard N. Eavenson, on Mining an Upper Bituminous Seam after a Lower Seam Has Been Extracted; J. J. Rutledge, on Subsidence in Two Oklahoma Coal Mines; Benjamin F. Tillson, on Caving Cracks at the Franklin Mine, New Jersey; Dr. F. W. McNair, on the Dome Theory; William Kelly, on disadvantageous effects in Mining and Back-filling Working Upward a Steep-Pitching Iron-ore Bed; Eli T. Conner, on the good results of Back-Filling by Hydraulic Means in Preventing Destructive Subsidence in the Anthracite District; Thomas H. Claggett, on the merit of Systematic Pillar Drawing in Preventing Cracks in an Upper Seam; Henry H. Otto, successful results in the anthracite district in Mining Lower Seams before Upper Seams; Douglas Bunting, on Leading Factors Incident to Successful Mining of an Overlying Seam; Edwin Ludlow, on there being "less damage to buildings when there was complete removal of coal with complete packing than when room and pillar is used without extracting the pillars"; Edward O'Toole on "bumps" in eastern Kentucky mines, which he thought were the result of geologic stresses: H. A. Buehler, on Upheaval of Surface in an Illinois Case in Advance of the Face; and R. Dawson Hall, on The Mechanics of Subsidence from Mining. The author of this paper discussed various kinds of problems of ground movement and subsidence in both metal mining and coal mining; the production of great landslides by workings near an outcrop, as at Turtle Mountain, Alberta, Canada; and general

Jan 1, 1939

By D. Turnbull, J. H. Hollomon, J. C. Fisher

The concepts of nucleation and of growth have adequately described the isothermal phase transformations to which they have been applied.ls2 However, these concepts have not yet been used successfully to describe the kinetics of a number of transformations that are not observed to take place isothermally. A typical reaction of this type is the austenite to martensite transformation in steels, for which the new phase appears only during cooling of the parent phase. If the cooling is interrupted, transformation ceases; yet had the cooling continued, transformation would also have continued. Nuclei of a new phase do not leap into existence all at once by the simultaneous cooperation of a large number of atoms or molecules of the parent phase; rather they are formed at finite rates by gaining or losing atoms one at a time from the surrounding materiaL3,4 Further thermo-dynamic considerations require a finite concentration of small transitory nuclei of all unstable phases to exist at equilibrium in a stable phase.= For steel in particular, nuclei of ferrite (a iron) exist at equilibrium in austenite (y iron) at temperatures where austenite is the stable phase. If a high-temperature phase a be cooled sufficiently rapidly from temperature TI above the a-ß equilibrium temperature To, to temperature T-1 below To where ß is the stable phase, the equilibrium distribution of ß nuclei corresponding to the high temperature will be retained. There are two limiting possibilities of particular interest: I. The steady state rate of nucleation of ß may be appreciable at T_1, and may require a concentration of sub-critical nuclei exceeding that retained from the high temperature. Time will be required then for the concentration of nuclei to build up to the steady state value, and an induction period will be observed during which the rate of nucleation will increase to the steady state value. 2. The steady state rate of nucleation of ß may be negligible at T-l, while the critical size for continuous growth of ß nuclei, which decreases with increased subcooling of the a phase, may reach a value so small that some. of the retained high-temperature nu-

Jan 1, 1949

By Richard Rothwell

At the last meeting of the Institute, Mr. Per Larsson read a very interesting paper on the Chapin mine of Michigan, in which he described the systems of mining that had, at different times, been tried in that great ore-body, and especially the system now in use, which consists in working the ore out from the bottom upward in lifts. Shortly after that paper was written, but before it had been published, or that I had had an opportunity of reading it, I bad the pleasure of visiting the mine. At that time I was making a profes sional examination of a nnmber of the mines on theGogebic Range, and others in the Menominee region, Michigan and Wisconsin, and had occasion then, as during several previous visits, to study closely the methods and cost of mining in these districts. As the outcome of these investigations, it appeared evident to me that the system of working on the chamber-and-pillar plan, which up to that time had been the only method of underground work adopted in the Gogebic

Jan 1, 1888

By Franz Fohr

On July 27, 1919, there passed away a simple, unassuming gentle-man, who, throughout his life, allowed his intense modesty to keep him-self in the background and during his later years effaced himself so thoroughly that but few of his acquaintances knew aught of him. Yet he was one of our accomplished metallurgists, who did good work in the practice of his profession and lived an upright life. Now that he is no longer with us Franz Fohr cannot plead to be overlooked, and those who fondly remember him will be gratified by his receiving his due. Franz Fohr was born, Sept. 7, 1838, in Mannheim, Germany. Of his ancestry, education, and early career we know scarcely anything. We do not even know just when he came to America, or. what led him hither. The first record of his professional work in this country, found among his papers, shows that from July, 1870, to Jan. 1, 1872, he was superin-tendent of the Newark Smelting & Refining Works, then owned by Ed-ward Balbach & Son. At that time the Balbach works at Newark, established in 1850, and the Selby works at San Francisco, established about 1866, were the only important silver-lead refineries in the United States. Mr. Fohr may have been associated with the Balbachs for some time before he became superintendent of their plant or he may have come from Germany but a short time previously. At all events, it is certain that he was at that time an experienced and accomplished metallurgist. After leaving Newark and going to San Francisco, he soon formed a connection with Thomas H. Selby & Co. Early in 1874-this firm sent him to New York to procure information respecting the manufacture of white lead. His engagement in New York terminated on-Jan. 31, 1875. During 1875, Mr Fohr spent some time at Silver Islet and in the Lake Superior copper region, but of his work there no record remains. In the latter part of 1875, or early in 1876, he associated himself as metallur-gist with the Boston Silver Co., operating at Saint John's, Summit County, in which William L. Candler, of Boston, was the moving spirit. That company was developing its mine in 1875. At the end of that year it "had about 800 tons of ore on hand, about three-fourths of which is dress-ing ore, to be concentrated in its very systematic establishment and to be smelted into pig lead." Evidently Mr. Fohr was engaged for the latter purpose. Henry A. Vezin, erudite and painstaking, was the mechanical engineer for the company. In the fall of 1876, Anton Eilers took his family for the first time so far West as Denver and Mr. Fohr went with them. I do not think that Mr. Eilers had any connection with the Boston Silver Co., save possibly in a consulting capacity, but he visited Saint John's and the enduring friendship among Eilers, Fohr, and Vezin, which terminated only with their deaths, dated from that time.

Jan 12, 1919

By William P. Roe, James F. Ellis, W. P. Fishel

This paper reports the distribution of sulphur between iron and titanium in Fe-Ti-S alloys and in Fe-Ti-C-S alloys. The compound TiS was found, which exists as a separate phase at temperatures below 1200°C. Titanium in steels reacts with sulphur in preference to carbon. THE general relationship between sulphides and oxides suggests that titanium should form a sulphide having properties similar to those of titanium oxide. Specifically, titanium should form a sulphide having a high melting point, indicating a stable compound of low solubility in iron. In order for titanium to function as a desulphurizer or sulphur-fixing agent, it must form a stable sulphide. In order for titanium to be useful in steels as a sulphur-fixing agent, it must react with sulphur in preference to carbon; and to prevent red shortness, the sulphide formed must have solubility characteristics such that grain-boundary precipitation of a low melting phase be prevented. The terms desulphurizer and sulphur-fixing agent when used in this paper mean that titanium effectively ties up the sulphur as a stable sulphide of titanium and prevents the formation of FeS. The partition of sulphur between iron and titanium was studied first in a series of Fe-Ti-S alloys with carbon absent, and then in similar alloys with carbon present. It has been established1 a that titanium forms in Fe-Ti-S alloys a sulphide of undetermined composition which can be identified microscopically, and that the titanium-sulphur compound does not respond to sulphur printing. It has been suggested" that titanium acts as a sulphur-fixing agent, although little proof has been given. A report% f The Advisory Committee on Metals and Minerals summarizes the existing knowledge concerning substitutes for manganese in steels. Distribution of Sulphur Between lron and Titanium with Carbon Absent The alloys for this investigation were made by -melting Armco iron, metallic titanium, and iron sulphide in alundum crucibles in an induction furnace. The titanium was added after the other ingredients had melted. In these alloys it is recognized that some TiO, is present, since the melts were made in the air and since no other deoxidizing agent was used; therefore, some of the titanium was not available for union with sulphur. Thirteen ingots were made. Ingots 2 to 8 were cast in baked-sand molds; ingots 12 and 13 were cast in metal molds; and ingot 9 was allowed to cool in the crucible in which it was melted. All ingots were annealed at 900°C for 3 hr and were cooled slowly in the furnace. Subsequent information indicates that this anneal had no effect upon the titanium sulphide particle size, since the sulphide does not go into solution at this temperature. The ingots as-cast were approximately 8 in. long and % in. diam. The compositions of the eight ingots and the results of the partition of sulphur are recorded in Table I. Total titanium and total sulphur were determined by standard gravimetric methods. Sulphur, as iron sulphide, was determined by the evolution method. Boiling HC1 (1:4) liberates the sulphur from iron sulphide, but leaves the titanium sulphide practically undecomposed. A complete separation of titanium sulphide and iron sulphide cannot be made by digesting these compounds in dilute HC1 since titanium sulphide was found to dissolve slowly. The amount of titanium sulphide decomposed will depend upon the time in contact with the acid and upon the particle size of the sulphide. The point

Jan 1, 1952

R. Trimble, Pittsburg, Pa (communication to the Secretary) : There are in the proposed specifications only two points on which I wish to comment at this time.

Jan 1, 1902