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By L. D. Fetterolf

The New Jersey Zinc Zompany operates at Depue, Illinois, an integrated zinc smelting plant using tie vertical retort reduction process. The overall operation comprises green concentrate roasting, sintering, vertical retort smelting and metal refining. In the roasting operation, the fine concentrate is pelletized, the dried pellets fluidized and autogenously roasted with air in a “fluid column” with minimal formation of dust requiring recirculation. The roasted pellets and any associated roaster dust are agglomerated in a rotating drum and laid down, in combination with coal for fuel, on a Dwight-Lloyd sintering machine which converts to a semi-fused mass - a physical state more suitable for vertical retort smelting. The smeltins plant of 27 vertical retorts rated at 8 T zinc each per day on average requires the following major processing steps - mix preparation and briquettine, briquet coking, vertical retort reduction, vapor condensation and slab casting of metal. A portion of zinc production is converted to 99.99+ percent purity by boiling and fractional distillation in columns consisting of externally heated, superimposed trays of high-conductivity refractory.

Jan 1, 1970

By H. L. Barr

THE following report covers the history of the development of the mine, present equipment, methods and costs of mining and milling. In addition, a description of the ore deposit is given with emphasis on the origin of the fractures, mode and types of ore occurrence, and mechanics of granite emplacement. An endeavor has been made to present a complete and accurate statement of the San Mauricio mine, the highest grade gold mine in the Philippine Islands. Credit is gratefully acknowledged to the mine staff for descriptions and details regarding their particular field of work. All analyses were made by Mr. T. A. DeVore, head chemist, San Mauricio Mining Co. Messrs. Edward Wisser, J. E. Fyfe, A. F. Skerl and W. B. Meek, geol-ogists, have contributed geologic information and ideas, for which thanks are extended. The Executive Committee of Marsman and Co., Inc., Managers of the Company, has kindly given permission for publication. Mr. J. B. Stapler, Division Manager, Marsman and Co., has had the courtesy to read the manuscript and to give critical and helpful suggestions.

Jan 1, 1940

Polluted air and water, despoiled land and excessive noise are the unwelcome results of the population growth and a rising standard of living. The consumption of goods and services, including metal products and minerals, by all people is increasing so rapidly that civilization is in danger of destroying the environment in which it lives. This is true because every human activity affects the environment, whether it is air, water or land. While E. F. Osborn, director, U.S. Bureau of Mines, says . . . "some members of the mineral industry are reluctant to recognize environmental demands" . . . William T. Pecora Under Secretary of the U.S. Department of the Interior.. . says that, "to maintain levels of resource development and environmental quality needed to satisfy our affluence, we must trade off values rather than turn off troublesome operations." What it seems to boil down to is how much control of its operations is the mineral industry willing to accept-internal policing or strict government control? The answer lies in how well the mineral industry maintains a balance between mineral development and environmental quality.

Jan 1, 1971

By William M. Agar

Now that both the national and state legislatures are seeking ways of reducing expenses, the appropriations for geological investigation and for the study of mineral resources have been greatly reduced and in some cases entirely stopped. Is this policy justified? The sums saved by these reductions are always small. If the work accomplished by these surveys has no intrinsic value to the community, but is only an interesting way of spending some of the people's money when that money is plentiful, there should be no surveys at any time. If, on the other hand, they perform a necessary function, it is indeed foolish and short-sighted to save these paltry sums to the detriment of the community. It is not my purpose to undertake a general justification of geological surveys. Rather, 1 wish to call attention to the work of one state survey that has been discontinued, and to indicate ways in which the work was valuable to the people, even though that state's mineral resources are not very important, and why it should be continued. Though at one time in Connecticut's history iron mining and smelting were important, and copper was mined in appreciable quantities in two localities, it is many years since it could be regarded as a mining state. At present Connecticut stands far down among the states in the value of its mineral products. Granite for architectural and structural purposes, trap rock, clay, agricultural lime, feldspar and quartz, together with a few other nonmetallic minerals, are produced in appreciable quantities, but the natural resources of the state consist at present much more largely in its attractive scenery, woods, lakes, shore line, and in the opportunities that these offer for rest and recreation. Is the prosecution of geological work in such a state a waste of the taxpayer's money? Or can it be that though it was formerly valuable, the work is now completed? The only way to answer these questions is to review the geological work done in the past and to consider the type of information the people want, as reflected in the requests that have been received by the director of the survey in the last few years. There have been two periods during which Connecticut has supported geological work within its borders. The first began in 1835 when Percival

Jan 1, 1935

By William M. Agar

Now that both the national and state legislatures are seeking ways of reducing expenses, the appropriations for geological investigation and for the study of mineral resources have been greatly reduced and in some cases entirely stopped. Is this policy justified? The sums saved by these reductions are always small. If the work accomplished by these surveys has no intrinsic value to the community, but is only an interesting way of spending some of the people's money when that money is plentiful, there should be no surveys at any time. If, on the other hand, they perform a necessary function, it is indeed foolish and short-sighted to save these paltry sums to the detriment of the community. It is not my purpose to undertake a general justification of geological surveys. Rather, 1 wish to call attention to the work of one state survey that has been discontinued, and to indicate ways in which the work was valuable to the people, even though that state's mineral resources are not very important, and why it should be continued. Though at one time in Connecticut's history iron mining and smelting were important, and copper was mined in appreciable quantities in two localities, it is many years since it could be regarded as a mining state. At present Connecticut stands far down among the states in the value of its mineral products. Granite for architectural and structural purposes, trap rock, clay, agricultural lime, feldspar and quartz, together with a few other nonmetallic minerals, are produced in appreciable quantities, but the natural resources of the state consist at present much more largely in its attractive scenery, woods, lakes, shore line, and in the opportunities that these offer for rest and recreation. Is the prosecution of geological work in such a state a waste of the taxpayer's money? Or can it be that though it was formerly valuable, the work is now completed? The only way to answer these questions is to review the geological work done in the past and to consider the type of information the people want, as reflected in the requests that have been received by the director of the survey in the last few years. There have been two periods during which Connecticut has supported geological work within its borders. The first began in 1835 when Percival

Jan 1, 1935

By H. L. Barr

THE following report covers the history of the development of the mine, present equipment, methods and costs of mining and milling. In addition, a description of the ore deposit is given with emphasis on the origin of the fractures, mode and types of ore occurrence, and mechanics of granite emplacement. An endeavor has been made to present a complete and accurate statement of the San Mauricio mine, the highest grade gold mine in the Philippine Islands. Credit is gratefully acknowledged to the mine staff for descriptions and details regarding their particular field of work. All analyses were made by Mr. T. A. DeVore, head chemist, San Mauricio Mining Co. Messrs. Edward Wisser, J. E. Fyfe, A. F. Skerl and W. B. Meek, geol-ogists, have contributed geologic information and ideas, for which thanks are extended. The Executive Committee of Marsman and Co., Inc., Managers of the Company, has kindly given permission for publication. Mr. J. B. Stapler, Division Manager, Marsman and Co., has had the courtesy to read the manuscript and to give critical and helpful suggestions.

Jan 1, 1940

By Louis V. Bender

THIS paper gives a short review of the installation for and the use of gas, as a. fuel, at the Anaconda Reduction Works of the Anaconda Copper Mining Co. Before putting in gas tile fuels used were pulverized coal, lump coal, coke distillate and oil. These fuels are now almost entirely eliminated. For nearly fifty years bituminous coals from Wyoming and Montana fields had been used. These coals were of a good grade, analyzing 11,300 B.t.u. and having an ash content of 12 per cent. When hydro-electric power replaced steam-driven equipment, the coal requirements were reduced; and, on account of improvements in metallurgy and/ or in furnace design, the quantity was lessened. Later, oil and distillate were introduced and used in some of the operations. All of these things tended toward the lessening of the amount of coal used, and had it not been for the increase in the size of the plant, the tonnage used would have been small when the change was made to gas.

Jan 1, 1932

1938 ABERNATHY, G E Feb 6, 1948 Min & Met Apr 1948 1937 ADAMS, ARMY Aug 20, 1949 Min Eng Dec 1949 1946 ADDY, GEORGE E Sept 24, 1950 Min Eng July 1951 1920 ALDERSON, WILTON P Feb 1951 Min Eng Sept 1952 1896 ALDRICH, T H , JR May 24, 1950 Min Eng Aug 1950 1942 ALDRIDGE, LEONARD June 8, 1952Jrn Met Sept 1952 1919 ALLEN, ROLLAND C July 18, 1948 Min &Met Sept 1948 1950 ANDERSON, C P Unknown Min Eng Feb 1951 1937 ANDERSON, JOHN H May 10, 1950 Min Eng Aug 1950 1914 ANDERSON, L DOUGLASS Unknown Min Eng Nov 1951 1948 ANDRAU, E W K Oct 20, 1951 1936 ANDREWS, CHARLES B Apr 19, 1950 Min Eng June 1950 1918 ARMITAGE, PAUL June 28, 1949 Min Eng Oct 1949 1924 ARMSTRONG, PERCY A E Jan 23, 1949 Min Eng May 1949 1906 ARNOLD, CHARLES LE NEVE Aug 7, 1949 Min Eng Oct 1949 1945 ARNOLD, HAROLD S Aug 7, 1950 Min Eng Oct 1950 1936 ASH, JAMES E Dec 17. 1949 Min Eng Apr 1950

Jan 1, 1952

By Charles E. Locke

CONTINUED expansion of gold mining in 1935 led to further developments in treatment methods. In base metals and non-metallics progress is also noted, coincident with greater activity. Statistics are not available yet for 1935 but the trend is shown by 1934 when nonferrous ore mined in the United States was 35,840,737 tons, or 45 per cent more than in 1933. The amount concentrated was 27,167,530 tons or 75.80 per cent of the ore mined, and flotation was used in whole or part on over 96 per cent of the ore subjected to concentration. In the crushing field a new model of the Fahrenwald crusher is promised soon. The Symons fine-reduction cone crusher and Traylor secondary crusher continue to gain as intermediate crushers. A new book entitled "Crushers for Stone and Ore" by William T. W. Miller appeared. The Hadsel mill has been improved still further and a number of installations are in satisfactory operation showing economical power consumption and low wear. An attempt in a

Jan 1, 1936

By Harry Seltz

INTERMETALLIC compounds are formed in many binary metal systems. Some compounds are stable to their melting points, and others decompose at lower transition temperatures. Even those of the first class are dis-sociated in the liquid state, as indicated by the continuous for in of their solubility curves at their melting points1. While the lattice structures of some of these compounds have been determined, their thermodynamic properties have not been investigated. In this paper is described the determination of the free energy and heat of formation of the compound CdSb, which is of the first class mentioned above, melting congruently at 455° C. This compound shows a rhombic structure, and the lengths of the edges of the elementary cell containing four molecules are: a =6.52, b = 8.60, c = 4.16 A.2 There are three possible methods of determining the free energy of formation of a compound of this type. The first method, applying the third law of thermodynamics, requires the measurement of its heat capacity preferably to liquid hydrogen temperatures, and a calorimetric determination of its heat of formation. The second method involves the study of the equilibrium of the compound in some gas reaction, such as: CdSb + CO2 = CdO + CO + Sb From the known free energies of formation of CdO, CO2 and CO the free energy of formation of CdSb could be calculated. The third method measures the electromotive force of a galvanic cell in which the cell

Jan 1, 1935

Reginald S. Dean (Manganese Extraction by Carbamate Solutions and the Chemistry of New Manganese-Ammonia Complexes, P. 55) was born in Rolla, Mo. and attended the Missouri School of Mines. Mr. Dean has worked as metallurgist with Western Electric Co. from 1920 to 1929 and with U. S. Bureau of Mines from 1929 to 1946 as chief metallurgist and assistant director, and has been a metallurgical consultant in Washington, D. C. since 1946. An AIME member, Mr. Dean has presented at least 50 papers before the society. Mr. Dean is a member of American Society of Metals, American Chemical Society and Electrochemical Society. C. O. Dale (Illinois Operations of the Eagle Picher Mining and Smelting Co., co-author with W. J. Rundel, P. 72) was born in Twin Bridges, Mont. and attended Montana School of Mines and received his B.S. in mining engineering in 1944. Mr. Dale was with U. S. Navy Air Corps. as an electronics technician and worked as an engineer with C. O. Dale & Sons, Anaconda Copper Mining Co. and with Eagle Picher Mining & Smelting Co. At present he is Wisconsin manager of Eagle Picher Mining & Smelting Co. The application of machinery to mining is of special interest to Mr. Dale. A member of AIME, Mr. Dale is on the Room and Pillar or Stope and Pillar Committee of Mining Subdivision for 1951 to 1952. Mr. Dale is a member of Montana Society of Engineers and Lions Club. Golfing, fishing and wood working are his hobbies.

Jan 1, 1952

By C. B. E. Douglas

In an interesting article on evaluation of the water problem at Eureka, Nev., W. T. Stuart describes how a difficult water problem, or one phase of it, may be evaluated by means of a small scale test. Test data are plotted by a method rendering, under certain conditions, a straight-line graph that can be projected to show how much the water table will be lowered by pumping at any specified rate for a given time. A formula is then used to determine the size of opening, or extent of workings, necessary to provide sufficient inflow to enable pumping to be maintained at that rate. At first glance this might seem the answer to a miner's prayer, but a word of caution is in order. It may not be the whole answer. Moreover, results obtained by the method described are reliable only for conditions approximating those assumed. Even where conditions do not meet this requirement, however, it may be possible to draw helpful inferences from the results, perhaps enough to facilitate another approach to evaluation of a problem.

Nov 1, 1955

By AIME AIME

THE papers presented at the geophysics session" on Feb. 17 were concerned largely with three aspects of the science. The first ones dealt with the transmission of elastic waves through the earth, then electrical methods came in for their share of attention and finally, the question of the teaching of geo- physics came up for the first time at these meetings. Also, for the first time, there was a symposium of mining men on the practical value of the new science. The paper (T. P. 267) entitled "Seismic Propagation Paths" was presented by Donald C. Barton in the absence of the authors. It dealt with an investigation of the speed of propagation of seismic waves. The latter travel in a straight line when proceeding at a constant velocity, but if the velocity increases at increasing depths, the line of travel becomes a curve. Under the assumption of the authors this curve is found to be the arc of a circle, and their paper gives calculations for reflected and refracted wave paths under these circumstances.

Jan 1, 1930

By K. R. Waugh, Barbara S. Brown, D. W. James

AN electronic data-processing system is described which permits rapid, accurate, low-cost processing of strain-dependent damping data utilizing equipment normally available within the service facilities of most large laboratories. On analyzing the record of a stress-dependent damping test, the operator usually measures the double amplitudes at several points on the decay curve. The logarithmic decrement is then calculated for decay between consecutive amplitudes. These values of 6 are plotted against the corresponding maximum surface shear stress, T, which is proportional to the average of the two amplitudes between which is calculated: where d is the specimen diameter. The period of the vibration is not necessarily constant during decay; thus, each cycle must be counted. A decay curve may extend to, perhaps, 1000 cycles, and at least two curves are always obtained for each specimen or set of conditions. It can, therefore, be seen that manual analysis of decay curves is both tedious and costly in terms of man-hours. Furthermore, the resolution of the record is often such that accurate measurement of amplitude is extremely dif-

Jan 1, 1969

By N. J. Grant, E. Gregory

The creep rupture properties of wrought aluminum powder products made from five grades of sintered aluminum powder were investigated at temperatures from 400° to 900°F for rupture times up to 1000 hr. The effect of stress concentrations on materials of this type was investigated by means of notched creep rupture tests. A tentative correlation was obtained between the creep rupture properties and the structure as revealed by electron micrographs. SEVERAL papers have been published recently concerning the production and properties of wrought aluminum powder products and their possible high temperature applications. Most of the published work in this field has come from abroad, notably Switzerland, and articles by Irmann and his colleagues were summarized in English recently.'.' Most of the papers published by Dr. Irmann are principally concerned with the retention of properties (by a product which is produced from extremely fine flake powder and is subsequently hot extruded) after heating to high temperature for prolonged times. The powder may be in atomized or flake form, and during hot working the applied pressure is reported to plastically deform the aluminum powder, thus breaking the oxide skin and welding the particles together. Irmann attributes the remarkable properties to the dispersion of oxide inclusions. Specifically, the product described by Irmann is one labeled SAP (Sintered Aluminum Powder) in which the initial flake powder is so fine that at least 50 pct of the flakes have one dimension of 2 microns or less. The composition of the starting aluminum shows in percent, Fe, 0.18; Si, 0.19; Zn, 0.06; Ti, 0.03; Cu, Mn, Mg, all nil; balance Al, approximately 99.5 pct. Aluminum is not the only material that has been found to have increased resistance to deformation at elevated temperatures when produced by powder metallurgy. It has been reported by Middleton, Pf eil, and Rhodes- hat platinum has a higher recrys-tallization temperature when produced by powder metallurgy and exhibits peculiar properties, many of which are similar to those of the aluminum powder products. Difficulties were encountered in explaining the reason for the strengthening in the case of platinum since the existence of the oxide is doubtful. The authors attributed the special properties to "a small amount of suitably dispersed porosity." This theory was supported by von -~eer-leder4 in the discussion to the paper, and the similarity between this method of hardening and that suggested by Rohner in his theory of age hardening was pointed out. R. de Fleury5 attempted to explain some of the properties in terms of the modulus of elasticity and elastic limit of alumina and aluminum while von Zeerleder examined the relationship between the yield strength and the reciprocal of the powder particle size. Boenisch and WiderholtQ dealt mainly with the corrosion resistance of the powder aluminum material and compared it with other aluminum alloys. The diffusion rates of other metals in SAP and pure aluminum have been compared by Seith and Lop-mann.' They showed that the alloying metals diffuse particularly quickly in SAP possibly due to the very fine grain size. The properties of the Alcoa products were given by Lyle.' The creep rupture properties of SAP and two of the Alcoa experimental powder products were compared by Gregory and Grant hnd it was shown that these products are vastly stronger at 900°F than are the best cast and wrought alloys at 600°F. Since the publication of these data, the authors have investigated two further aluminum powder products and it is the object of this paper to show how the high temperature creep rupture properties of the five materials vary with oxide content and with the structure as revealed by electron microscopy. Materials One of the five products, SAP, a sintered aluminum product, was supplied by the Societe Anonyme pourl Industrie de l,Aluminium, Neuhausen a/RHF, Switzerland, through Dr. R. Irmann, while the others, M276, M257, M293, and M255 were supplied by the Aluminum Company of America as experimental powder metallurgical products. M255- and M293 were made from coarse and fine atomized powders, respectively. The other materials were made from flake powders with significant differences in oxide content, the details of the type of powders used in the manufacture of these materials

Jan 1, 1955

By J. P. G. Farr, R. Brownsword

THE role of solute segregation in the formation of cellular solidification substructures in tin and its dilute alloys is well-established, see, e.g., Ref. 1. Segregation has been shown to persist during cooling, enabling solidification structures to be studied from sections taken at some distance behind the interface. In the present work, a single crystal of commercial nickel, 99.965 pct, was examined in this way. The crystal was cut from the center of a rod given a single pass in an electron beam floating zone melter. Polished sections of a nickel specimen taken normal to the growth direction showed a very fine precipitate phase, the distribution of which varied over the section. The identification of the phase proved difficult because of the small amount present and the small particle size, about 1 p: but it was shown by probe microanalysis to contain only nickel and oxygen in detectable concentrations and was probably nickel oxide, NiO. Bulk analysis of the material before melting showed there to be only 3 to 4 ppm of oxygen present, thus demonstrating a very considerable segregation concentration effect. In some areas of the section the precipitate formed a discontinuous hexagonal network suggesting decoration of the cellular boundaries known to be present in the sample2 whereas in a restricted region the precipitate formed small clusters. Occasionally it could be seen that the clusters were at the intersections of an hexagonal network of cellular dimension. It was suggested3 that this was the result of enhanced segregation to the cell boundary intersections whereas general cell boundary segregation was insufficient to give a precipitate. Enhanced nodal segregation has since been demonstrated in a number of systems.1, 4-8 The development of a suitable electrolytic etching technique (perchloric acid 20 pct v/v; ethyl alcohol 70 pct; glycerol 10 pct; current below electropolishing plateau; 1 to 2 sec etching) suggested the association of the phase with regions of solute segregation (where ko < 1); in these regions anodic attack produced grooves or depressions. In a study of the variation of solidification substructures with degree of constitutional supercooling, Biloni et a1.&apos; appear to have used standard growth conditions and varied the solute concentration. They were able to produce in a series of individual tin crystals examples of substructure ranging from planar interface through various cellular structures to den- Fig. 1—Electroetched section taken normal to the rod axis; the center of the rod lies to the left and the periphery to the right of the micrograph. The variation of structure across the section is evident. Magnification 60 times. drites. It was possible in the present nickel crystal to observe a continuous range of substructures varying with degree of supercooling across a single section as shown in Fig. 1. Growth rate, 13 mm per min, and temperature gradient were essentially constant; the variation in structure is thought to be due to a radial gradient in solute concentration ahead of the solid interface. The liquid at the interface is likely to have been richer in solute toward the periphery of the zone, the result of curvature of this interface. The type of substructure was seen to vary with increasing constitutional supercooling as follows: a) region free of precipitate. top left, Fig. 1: 6) region of nodal precipitates which became arranged in hexagons on passing from the center of the rod: c) irregular hexagonal cells with incomplete boundary precipitation; d) regular hexagonal cells of decreasing size with complete boundary precipitation. Fig. 2 shows the transition from stage 6 and Fig. 3 shows the structure in stage d. Within stage 0, the range of conditions over which irregularly positioned nodes occur appears to be small and the nodes are soon recognizable as taking up positions at the intersections of an hexagonal network as the supercooling increases.

Jan 1, 1970

A mine in the mountains of southeastern British Columbia is fast earning a reputation as the safest metal mining operation of all time. Already officially proclaimed as the safest mine in Canada, the H.B. mine of The Consolidated Mining and Smelting Co. of Canada (Cominco) continues to advance its safety performance far in the lead of average accident frequencies in mines across the country. Official recognition came its way again this spring when the Cominco mine was awarded the John T. Ryan trophy for the fourth time in the last five years. This award is emblematic of top national safety performance of a metal mining operation. The H.B. mine is its only four-time winner. The Ryan award is based on a frequency of accidents involving lost time of more than six days. In each of the years that the H.B. has won the award-1958, 1959, 1961 and 1962-its frequency was zero, with no accidents involving a time loss of more. than six days

Jan 12, 1963

By V. T. Stringfield, H. H. Cooper

ONE of the earliest investigations of ground water in Florida was made in 1513 when Ponce de Leon arrived at St. Augustine in search of the Fountain of Youth. The history of the development of the water resources of the State shows that the large artesian reservoir that underlies Florida was discovered in the latter part of the last century. Part of that history is given by L. C. Johnson&apos; who states that the first successful artesian well in Florida was drilled at St. Augustine between 1880 and 1882. After the City of Jacksonville failed to obtain a flow of artesian water at a depth of nearly 400 ft and abandoned the drilling, R. N. Ellis, City Engineer, and L. C. Johnson, using Johnson&apos;s knowledge of the geologic structure of the artesian reservoir, estimated correctly that artesian water could be obtained at a depth of about 500 ft. Thus began the development of the large artesian system in the northeastern part of the State. In 1908, the Florida Geological Survey issued its first report on the ground water of central Florida. More recent reports give the results of investigations that have been in progress in cooperation between the Florida Geological Survey and the U. S. Geological Survey since 1930. As a result, the ground-water geology and hydrology of Florida are now so well known that ground-water problems such as confronted early investigators no longer exist. However, new problems arise and new discoveries are made as the demand for more ground water increases with the development of the State. Water-Bearing Formations Descriptions of the geologic formations and a map showing their distribution at the surface are given in a recent report by Cooke.&apos; The geologic formations that yield the ground-water supplies in Florida represent only a small part (about 1000 ft) of the total thickness of the sedimentary rocks (more than 15,000 ft) that underlie Florida. The water-bearing rocks that yield fresh water include more than two dozen formations that range in age from Eocene to recent. The Eocene formations, which consist chiefly of limestone, are the oldest and the deepest of the formations in Florida that yield fresh water to wells. In 1944, on the basis of a study of the foraminifera, the Applins -ivided the limestone of Eocene age into six formations, which are as follows, from top to bottom: Age or group Formation Jackson Ocala limestone icAvon Park limestone Claiborne -j Tallahassee limestone aLake City limestone Wilcox Salt Mountain limestone xOldsmar limestone The Ocala limestone and the underlying formations of Claiborne age, along with some of the overlying limestone of Oligocene and Miocene age, constitute the principal source of water in Florida and southeastern Georgia and generally may be regarded as forming one artesian aquifer or water-bearing unit. This aquifer is referred to in this paper as the Floridan aquifer, a name proposed by Parker.&apos; In part of Seminole County alone more than 1000 flowing wells yield water from the Floridan aquifer. A yield of 6500 gpm, or about 9.5 million gal per day, by natural flow from a well penetrating the aquifer at Jacksonville, Florida, was observed in 1942. A yield of about 7000 gpm by natural flow was reported for a well 1390 ft deep at St. Augustine in 1887. The largest yield reported from a pumped well penetrating the aquifer is 7500 gpm, or about 10.5 million gal per day. The aquifer is also the source of some of the large springs, such as Silver Springs, whose discharge, according to measurements made by the U. S. Geological Survey, has ranged from 526 to 1350 sec-ft, or from 340 to 872 million gal per day. The top of the Ocala limestone, as represented by contours in Fig. 1, indicates in a general way the geologic structure of the formations that comprise the Floridan aquifer. The Ocala is at or near the surface in the areas represented by shading in the northwestern part of the peninsula and also in an area in western Florida adjacent to Alabama and

Jan 1, 1952

Tars Committee is the result of a desire of the authorities in charge of the publications of the four national engineering societies to co-operate in this matter. The members of the Committee are the following: Charles WarreN Hunt, Secretary of the American Society of Civil Engineers. D. S. Jacobus, Vice-President of the American Society of Mechanical Engineers. Joseph Struthers, Assistant Editor of the American Institute of Mining Engineers. CaRy T. Hutchinson, Chairman of The Editing Committee of the American Institute of Electrical Engineers. This Committee has held several meetings; it seemed advisable, at the outset, to limit its discussions closely to the general subject of abbreviations. Further, it seemed best to formulate a few general rules to be followed in making abbreviations, rather than to compile a list of forms to be recommended. The Committee decided to limit the subject more narrowly by considering only abbreviations to be used in the text, or general reading-matter, arid not those to be used in special matter,

Jan 1, 1905

By Robert S. Shoemaker

Recently we read a short article which stated that Marcona Corp. was studying the use of 25,000-hp autogenous grinding mills for an iron ore project in Alaska. As if that weren&apos;t enough, they were going to dispense with the primary crusher and feed run-of-mine ore to the grinding mills which were to be driven by wrap-around seven-cycle motors. We see also that Bougainville Copper Co. will be grinding 90,000 tpd of ore in only eight 4250- hp ball mills. At Bougainville too, their float section will be the first large one to be completely equipped with the new 350-cu ft flotation cells. After a half century of relatively peaceful growth in the minerals industry, we are now seeing almost exponential advances in both equipment and plant size. At the same time, we are seeing a constant blending of hydro and pyrometallurgical techniques and processes into minerals beneficiation until the sample grind-&apos;em-up-and-concentrate-&apos;em plant is becoming a rarity.

Jan 1, 1970