Search Documents

By Fred C., Fred C. Bond

Comminution energy is principally energy of deformation before breakage, which appears as heat. An empirical equation is presented which covers the entire comminution range. The new strain-energy theory considers comminution from the known principles of mechanics and the reduction ratio. Energy requirements according to the different theories are compared.

Jan 1, 1950

Recognizing the fact that the problems of the committee named by the Board to prepare the "official ticket" for officers and Directors of the Institute are various and difficult; and desiring to assist this committee by setting forth some of the principles that should guide the committee and some of the qualifications that should be required of candidates, the following instructions are formulated and the Secretary is directed to publish them in MINING AND METALLURGY concurrently with the publication of the names of each newly appointed Nominating Committee and to send a copy to each member of the Committee

Jan 1, 1943

By Charles E. Wait

The old laboratory at the School of Mines was among the notoriously bad ones, being situated in apartments of the main collegebuildings not originally intended, and conspicuously unfit, for the use to which they were put; while, as in many of our schools and colleges, the assaying was done in the basement of the college. Prominent among the disadvantages of such an arrangement are insufficient light, poor ventilation, and little or no provision to carry off offensive gases. It is not my intention now to present a complete description of this building. I wish merely to call attention to a few points in its construction and equipment, which may prove of interest to those who contemplate erecting buildings for snch work, and who may be, as we were in this instance, limited as to funds. In this laboratory every room is well lighted; all rooms used by students are well ventilated, and are provided with closed hoods for

Jan 1, 1887

By Edgar T. Wherry

EDGAR .T. WHERRY,* Washington, D. C. (communication to the Secretary ?).-Dr. Pogue's presentation of the facts concerning the emerald deposits is very clear and convincing, and the only addition that I can suggest is a summary of previous theories of origin. He makes it evident that the pegmatite theory is the only one capable of explaining the existing relations, but upon certain details there may be some difference of opinion. If I understand the term pneumatolytic, it does not imply that all the elements concerned in a given deposit were transported as gases, but rather that the crystallization of these elements into the various minerals was favored by the presence of certain gaseous substances, notably H20, C02 and HF. It is highly improbable that the oxides of glucinum, aluminum, chromium, and silicon, which enter into the composition of the mineral emerald could have been transported in the gaseous form. The same is true of the metallic constituents of the parisite and other associated minerals. The explanation suggested, that solutions separated into liquid and gaseous portions, the latter ascending and forming the emerald in the upper portions of the rock only, therefore, seems to me untenable. When two formations exist side by side and one, A, is mineralized while the other, B, is barren, the possible explanations may he classed as (1) chemical, and (2) physical. 1. Some chemical feature of A not found in B might have caused crystallization of certain minerals in the former, which did not appear in the latter. In the present instance both rocks appear to be so similar chemically that no such effect can be looked for. Pogue mentions carbon as a possible precipitating agent, but describes both formations as carbonaceous, so that the difference in the minerals of the two can not be thus explained.

Jan 10, 1916

The earliest record of production in this county is for drilling a salt well in 1809. Some scattered data are shown in the table; the total figures are estimated. Little coal could be shipped in this period on account of lack of transportation. [ ]

Jan 1, 1942

By J. J. Forbes

THE Federal Coal Mine Safety Act (Public Law 552, 82nd Congress) was approved on July 16, 1952. It incorporates, as Title I, the Coal Mine Inspection and Investigation Act of May 7, 1941 (Public Law 49, 77th Congress), which gave Federal inspectors only the right to enter coal mines for inspection and investigation purposes but no power to require compliance with their recommendations. Title II contains the enforcement provisions of the act; its purpose is to prevent major disasters in coal mines from explosions, fires, inundations, and man-trip or man-hoist accidents. At this point a brief account of events that pre- ceded the enactment of the Federal Coal Mine Safety Act seems appropriate. The hazardous nature of coal mining was recognized by the Federal Government as long ago as 1865, when a bill to create a Federal Mining Bureau was introduced in Congress. Little was done, however, until a series of appalling coal- mine disasters during the first decade of this century provoked a demand for Federal action. As a result an act of Congress established a Bureau of Mines in the Department of the Interior on July 1, 1910. The act made it clear that one of the foremost activities of the Bureau should be to improve health and safety in the mineral industries. One of the first projects selected by the small force of engineers and technicians then employed was to determine the causes of coal-mine explosions and the means to prevent them. By investigations after mine disasters the fundamental causes and means of prevention were soon discovered, and the coal mining industry was informed accordingly. However, despite this knowledge and the enactment of State laws and the Federal Coal Mine Inspection and Investigation Act of 1941, mine disasters continued to occur with disheartening frequency and staggering loss of life. The devastating explosion at the Orient No. 2 mine on December 21, 1951, resulted in the death of 119 men. The Orient disaster rekindled the memory of the Centralia, I11., disaster of March 25, 1947, which caused the death of 111 coal miners. These two tragedies ultimately brought about enactment of the Federal Coal Mine Safety Act.

Jan 1, 1954

By W. L. Crentz, E. E. Donath, D. Doherty

Maurice Rey—The influence of cyclone diameter upon the fineness of separation is an important point which, however, cannot be discussed adequately if the injection pressure or the rate of flow are not specified. Perhaps some light can be thrown on the matter by using the formulas derived by Dahlstrom. Let us consider several geometrically similar cyclones where the apertures e and b are equal and proportional to the diameter D and which are operated with the same pressure drop. Eq 8 of Dahlstrom's paper can be written: Q Q = K D'. " or. if F is constant: Q = K D18 K is a constant of proportionality. Introducing this value of Q in eq 13 gives elimination efficiency = K D0' " Elimination efficiency, in the terminology of Dahlstrom, means the diameter of particles, in microns, which divide equally between the underflow and the overflow. This denomination is regrettable and it would be preferable to call it diameter of separation or characteristic size or any other name connoting a size rather than an efficiency. Whatever the name used, the above equation shows a slow increase in the fineness of separation when the diameter of the cyclone decreases. For example, if a 14-in. cyclone gives a 400-mesh separation (37 microns), geometrically similar cyclones, having the same pressure drop will give separations at the sizes shown below.

Jan 1, 1951

By E. E. Donath, W. L. Crentz, D. Doherty

Maurice Rey—The influence of cyclone diameter upon the fineness of separation is an important point which, however, cannot be discussed adequately if the injection pressure or the rate of flow are not specified. Perhaps some light can be thrown on the matter by using the formulas derived by Dahlstrom. Let us consider several geometrically similar cyclones where the apertures e and b are equal and proportional to the diameter D and which are operated with the same pressure drop. Eq 8 of Dahlstrom's paper can be written: Q Q = K D'. " or. if F is constant: Q = K D18 K is a constant of proportionality. Introducing this value of Q in eq 13 gives elimination efficiency = K D0' " Elimination efficiency, in the terminology of Dahlstrom, means the diameter of particles, in microns, which divide equally between the underflow and the overflow. This denomination is regrettable and it would be preferable to call it diameter of separation or characteristic size or any other name connoting a size rather than an efficiency. Whatever the name used, the above equation shows a slow increase in the fineness of separation when the diameter of the cyclone decreases. For example, if a 14-in. cyclone gives a 400-mesh separation (37 microns), geometrically similar cyclones, having the same pressure drop will give separations at the sizes shown below.

Jan 1, 1951

By Philip J. Shenon

IN 1947 the mining industry strove desperately to regain operating normalcy. During the first part of the year the industry in this country was plagued with labor shortages, strikes, and portal-to-portal lawsuits. Then followed the uncertainty of Government policy with respect to subsidies and tariffs; and the long and bitter controversy as to whether we are a nation of mineral "haves" or "have-nots." As the year progressed the labor supply impoved somewhat and the Taft-Hartley law brought partial relief to strike-troubled industry. The uncertainty with respect to tariffs was partly answered by President Truman on April 29 when he announced the suspension of the 4¢ import duty on copper until March 31, 1949, and later, near the close of the year, by the announcement of the tariff agreement signed by the United Nations at Geneva. By this agreement tariff rates are to be adjusted downward, or "bound" at their present levels, for three years, on commodities amounting to some 60 per cent of United States trade. Effective Jan. 1, 1948 the rate of duty will be substantially reduced on ores, concentrates, or metals of zinc, aluminum, copper, manganese, tungsten, iron, steel, barytes, nickel, cadmium, and antimony.

Jan 1, 1948

By C. K. McArthur

THE subject of classification is so broad that this discussion is confined to what the author believes is of prime importance in connection with proper grinding and classification. The years passed have witnessed many noteworthy changes in fine grinding and classification, which have been accompanied by a readjustment of ore-dressing flowsheets for the preparation of better ground and/or sized products at an expenditure of less power, steel and maintenance than formerly. Nowhere in the industry is more being done in the way of experimental work to lower costs than in grinding circuits, because, at best, grinding costs are high. Recent years have indicated that, on the average, finer grinding has a real application. Without careful preparation of the process feed, no operation can be highly efficient or successful. In an earlier paper, the findings of an extensive survey at representative concentrators were presented1. Also, in the year of 1935, a technical discussion was given by Dr. J. V. N. Dorr (Some Notes on Classification Trends in America) before the Chemical, Metallurgical and Mining Society of South Africa In both papers mentioned, much has been said regarding flowsheets, grinding and classification. The author is very familiar with these papers, having had considerable to do with the actual operation of the flowsheets, as well as large mills and classifiers in the work described. Some data from the second paper have been included in the following discussion. Circulating Load In this particular paper it seems advisable to deal with the classification phases of the work that to a major extent govern the success of any closed-circuit grinding unit. The question has often been asked in connection with a closed circuit: "What circulating-load ratio should be carried?" This is really an

Jan 1, 1937

By T. H. Aldrich

(San Francisco Meeting, October, 1911.) THERE are two conditions generally prevailing upon the earth-those within atmospheric influence, tending towards oxidation, and those away from atmospheric influence, tending towards reduction. Practically all mineral substances from mines of any depth are in a reducing condition. Since the cyanide process, in order to dissolve silver or gold, requires that the prevailing conditions under which it operates shall be oxidizing, and the materials usually acted upon being of a reducing character, it becomes necessary to supply oxygen to the solution carrying the cyanide. This oxygen is usually supplied through the medium of dissolved air in the solution, or through the medium of various chemical compounds, which upon combining with the solution or the ore give off a part of their oxygen. Strange as it may seem, practically all mineral substances are partly soluble in water, especially water carrying alkali or cyanide. The greater the surface exposed and the finer the material is ground, the greater will be the rate of dissolving of the reducing agents from the ore into the cyanide solution. In most cases, if the solution carrying the ore particles is agitated with air, the air will dissolve into the solution faster than will the reducing-agents; but in some cases the reducing-agents will dissolve more rapidly on account of easy solubility or greater surface exposed. It is a dissolving race between the oxygen from the air and the reducing-agents from the ore, and if the reducing-agents predominate, cyanide will not dissolve the gold from the ore. In many cases it will dissolve some of the gold, because in a mass of irregular shape some of the gold particles might be exposed upon the outside surface of a particle of rock;' but if the solution had to penetrate through cracks, the side-walls of which were lined with reducing-agent-

Feb 1, 1912

By M. J. Sinnott, H. B. Probst

AN extensive survey of the factors which affect austenite grain growth has already been made.' These factors are temperature, time at temperature, rate of heating, initial grain size, hot-working, alloy content, ofheating,initialand rate of cooling from the liquidus-solidus temperature. In the present work, a vacuum-melted temperature.electrolytic iron was used and the variables studies were temperature, time at temperature, and prior ferrite grain size. Other factors were maintained constant. The iron used in this study was vacuum-melted electrolytic iron of nominal composition of impurities of 0.07 wt pct. It was supplied as a ½ in. round cold-drawn bar. This iron was tested in three conditions: as-received, annealed 6 hr at 1200°F, and annealed 6 hr at 1600°F. Samples were ? in. disks cut from the bar. The prior anneals were carried out in vacuum and the isothermal treatments were carried out in vacuum-sealed Vycor tubing. The thermal etch technique was employed to determine the austenite grain size. Prior to sealing the test specimens, one surface of the sample was polished metallographically. This surface, after heating, was examined to determine the austenite grain size, since the austenite boundaries are revealed by thermal etching. This is essentially the only technique available for measuring the austenite grain size of low carbon steels or pure irons without altering the composition. It has been shown to yield results that are in agreement with other methods used for determining austenite grain sizes.' The specimen size was quite large compared to the grain size measured, so inhibition of growth due to size effects is probably negligible. After vacuum sealing, each sample was placed into a furnace at temperature and at the completion of the run was quenched into a mercury bath. The growth temperatures used were 1700°, 1800°, 1900°, and 2000°F controlled to -~10"F. Growth times were varied from 10 to 240 hr. The long times were used in order to eliminate the nucleation and growth effects occurring during the initial transformation. Time was measured from the introduction of the capsule into the hot furnace to the time of quench. Grain-size measurements were made with the use of a grain-size eyepiece of a microscope. By determining the number of grains per square millimeter at X100 and taking the square root of the reciprocal of this number, the average linear dimension of the grains was determined. Figs. 1 and 2 are plots of these data as a function of time and temperature for the various conditions investigated. The variation of D, the linear dimension of the grains, was assumed to follow the equation3 D = A tn. The curves of Fig. 1 were obtained from the data by the use of the least-squares method of analysis. Fig. 1 is for the growth of the as-received stock and Fig. 2 is for growth after prior treatments. Differentiating the foregoing equation gives an expression for the rate of growth dD/dt = G = nAtn-1 = nD/t. Both D and G as functions of t are given in Table I. It should be noted that G is a function of time; the growth rate is rapid at early stages and decreases with increasing time. Since increasing temperature increases the growth rate, it has been common practice to use the empirical relationship G = Go e-Q/RT to relate temperature to growth rate. The growth rate customarily has been taken at constant values of D on the basis that the rate of growth is related to the boundary surface tension and this is measured by the curvature of the boundary. At constant D values, the growth rate is a function of time and temperature. The growth rate can be related however to temperature at constant time, and this has the advantage that under these conditions the growth rate is a function only of temperature. Obviously the Q values, activation energies, obtained for each assumption will not be the same and the question of which is the more correct is a moot one, since the assumed exponential relationship in either case has no particular theoretical significance. By plotting G, at constant grain size, vs 1/T, the activation energy over the temperature range of 1800" to 2000°F is found to vary from 30,000 cal per mol at the smaller grain sizes to 50,000 cal per mol at the larger grain sizes. The 1700°F data do not correlate with the data at higher temperatures. The activation energies for the 1200" and 1600°F prior annealed materials were calculated as 50,000 and 62,000 cal per mol, respectively, using the reciprocal time to a given grain size as a measure of the growth rate. Plotting G, at constant times, vs 1/T yields an activation energy of 12,300 cal per mol for the tem-

Jan 1, 1956

By AIME AIME

WHEN Russell B. Paul was born in Russell Gulch, Gilpin County, Colorado, that district was the state's leading gold producer. The son of Dr. Henry Paul, who had gone to Colorado from Missouri during the golden era following the Civil War, and had joined the Institute in 1889 when he was manager of the famous Aspen mine, young Paul's early life was steeped in a mining atmosphere from which developed his selection of mining engineering as a profes¬sion. After receiving his E.M. degree from the Colorado School of Mines in 1902, Mr. Paul worked in Colorado and Honduras. Returning from Central America he was married to Mary Ellen Gilmour, daughter of a prominent Central City mining man;

Jan 1, 1943

POSITIONS VACANT (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) Assayer and chemist with experience in gold and silver work and refining; used to handling a force of men. Large property in Northern Ontario. Send reference, record of practice, age, married or single, and salary expected. Apply Position 54. Metallurgical chemist wanted, competent to make the following analyses: cupola, gray iron; air:-furnace iron; pig iron of various kinds; coal; coke; sand of all descriptions; materials used in modern foundry practice; steel, and bronzes of all kinds; oils for fuel in Diesel engines and lubricating purposes; materials used in a modern machine shop, in fact, all materials likely to be used in a foundry, machine shop and forge shop. No. 55.

Jan 12, 1915

Jan 1, 1949

By E. A. Holbrook

Research, primarily, is finding out the truth. Research applied to enigeering opens the door to new principies and processes, the application of which benefits mankind in a material way. The engineer believes that investigation instituted with the primary view of making the results directly applicable to the industries is the highest type of research. Coal is essentially the basis of modern industrial civilization; therefore, any considerable research pertaining to coal must link itself to the industry by practical application of the results of the research. In other words, all investigational work connected in any way with coal leads to conclusions that permit a better understanding of the origin, nature of occurrence, composition, better and safer mining, more careful preparation, or greater efficiency in utilization of coal. Modern engineering research has been fostered essentially by universities and in the laboratories of institutions of learning. Coal problems that lend themselves to solution in the laboratories have been first attacked and are perhaps the farthest toward solution. For example, a great amount of research work has been carried out with the various phases of chemistry connected with coal. On the other hand, the equally important problems connected with methods of mining have received but little attention, primarily because their solution involves the continued use of a great and expensive laboratory, which is none other than the mine itself. As many of the problems already solved have had chemistry as their background, so many of the problems unsolved have physics as their background; there are also unsolved problems that deal in coal economics. Even psychology must be called upon in future coal-mining research as a basis for solving those great problems that deal with human relationships. 'In general, considerable advance has been made in coal research dealing with chemistry, not so much progress has been made with problems having physics and engineering as a background, while there is a tremendous range of untouched problems that deal essentially with business and psychology. Research in coal mining is not a new development. In the chronicles of the northern coal trade as published in the Transactions of the North

Jan 1, 1920

By Frank Firmstone

The material described below was made at Furnace No. 2, Longdale, Va., Oct. 28, 1907, during a sudden derangement of working, in the course of which the furnace became entirely bridged over and for some time no solid material whatever descended into the hearth. This caused the hearth to become so completely emptied that, at the tuyere-level, a pricker put in at one tuyere could be seen by looking in at the opposite one. The tap-hole was opened and the iron got out with some difficulty. It ran sluggishly, throwing many sparks, but was not too thick to run into the chill-molds. Naturally, the product was assumed to be white iron, which is almost always produced under similar circumstances; but on removal front the molds it proved to be very strong and tough, although full of blow-holes. Most of these blow-holes bad bright, unoxidized walls. The iron could be drilled by using a "special steel" drill, the drillings curling up similarly to those of steel. An analysis by P. W. Shimer of this unusual product gave: Si, 0.019; P, 0.228; S, 0,39; Mn, 0.042; C, 2.366; and graphite, 0:000 per cent. A cast of iron made just before the disturbance contained P, 0.98, and Mn, 1 per cent. The peculiar product seems to have been decarburized in the hearth and, at the same time, to have lost much phosphorus and manganese, either by the action of the blast in the empty hearth, or, more probably, by. contact with the cinder rich in iron which was formed at the time. Unfortunately, no specimen of the cinder was preserved, so its composition cannot be given. It seems very remarkable that, with the furnace in bad condition, the temperature should be high enough to keep such

Sep 1, 1908

By Gill Montgomery

At this moment in the history of the world, the all- pervading and universally most important fact is that the world population is beginning to outgrow its food supply, and the United States has suddenly lost its ability to give away huge food surplus to any nation in the world with a food shortage problem. This, of course, means that, all of a sudden, our government must completely reverse its former bureaucratic stance regarding crop controls and agricultural price supports, to out-right incentives to increase farm production and bring more idle land into food-growing use.

Jan 2, 1967

By M. J. Pool, P. J. Spencer

Using liquid tin as the solvent metal, the heats of solution of silver and gold in dilute Ag-Au-Sn alloys have been determined at 723°K by solution calorimetry. From the values obtained, the various enthalpy interaction coefficients in the liquid solutions have been calculated. The self-interaction coefficients Au and Ag values of 2413 and -6322 cal per g-atom in binary Au-Sn and Ag-Sn alloys, respectively. For an alloy containing 0.04 mole fraction Ag, Au is equal to 2443 cal per g-atom, and in an alloy containing 0.04 mole fraction Au, Ag has a value of —8883 cal per g-atom. Ag Au has been determined as —2650 cal per g-atom. ADDITION of a second solute to a dilute binary alloy may cause striking changes in the thermodynamic characteristics of the alloy. As yet, such influences cannot be reliably predicted and it is only by accumulation and critical assessment of data that definite patterns can be established. Solute interactions in dilute solutions were first treated mathematically by Wagner,1 who derived expressions for the Gibbs energy interaction coefficients. For an alloy consisting of. two dilute solutes, i and j, in a solvent s, these coefficients are given by: where yi is the activity coefficient of component i and x represents the mole fraction of solute or solvent. Other interaction coefficients have since been established in terms of the various partial molar thermodynamic properties of an alloy; the definitions of these are summarized in a recent paper by Lupis and Elliott.2 Mathematical and experimental studies of such coefficients have received much attention recently, providing a very useful theoretical background to an understanding of the nature of solute interactions taking place in dilute solutions. One of the definitions to arise from such work has been the extension of Wagner's treatment by Lupis and Elliott4 to include an enthalpy interaction coefficient, defined as. where ?Hi is the relative partial molar enthalpy of component i. ?Hi is related to the relative partial molar enthalpy at infinite dilution, ?Hio, and to the enthalpy interaction coefficients by the expression: Values of ?Hi can often be obtained with a high degree of accuracy by calorimetry, and, if the composition of the alloy is carefully controlled by making calculated solute additions throughout a series of measurements, application of Eq. [2] will enable reliable enthalpy interaction coefficients to be determined. Partial heats of solution must be investigated as a function of solute concentrations down to xi = 0, and, since ? values are obtained from the slope of mi plotted against x, great care must be taken to obtain precise data. The data for binary systems which are presently available often require extrapolation of ?Hi values from compositions as great as xi = 0.05 or even 0.1 to obtain limiting heats of solution. Reliable enthalpy interaction coefficients are thus impossible to obtain from published data for most of the alloy systems already investigated. The aim of the present work was to determine values of Au, Ag, Ag, and Au in the limit xsn -1 for the relatively simple Ag-Au-Sn system and from these results to gain some insight into the possible influence

Jan 1, 1969

By Will Clark

HE who enters a mining claim within an Indian reservation of the United States of America acquires no rights thereby, because of the fact that the lands within such Indian reservation are not a part of the public domain, and cannot be located or acquired as mineral land. However, where such an entry is authorized as to a particular reservation by an Act of Congress, such claims as may be entered under such authorization are thereby segregated from the reservation, and the Indian title is extinguished. Under the Choctaw Constitution, any citizen of that nation, in other words any Choctaw Indian, who discovered a coal mine, acquired an exclusive right to all coal within a radius of 1 mile. The laws of the Chickasaw nation provided for the formation of corporations to develop coal and other mines, with authority to contract with others to develop and work the mines. Under these laws, leases were made; but Congress subsequently abrogated all existing leases, prohibited all persons from receiving royalties from such mines, and provided that all coal within the nation should remain the common property of the tribes. Such leases are now expressly prohibited by an Act of Congress (32 United States Statutes at Large, 655). All leases of mineral lands upon Indian reservations must now be made under regulations promulgated by the Secretary of the Interior, and the royalties must be paid into the United States Treasury for the benefit of the tribes. In Canada the Indians have no rights to the royal mines and minerals, and the government can make no stipulation with the Indians which would affect the rights of the Province in which the lands are situated. Therefore, while it is true that under our present law no rights can be acquired to a mining claim within an Indian reservation, it seems to be fully within the authority of Congress to make laws, giving such rights to mineral locators as it may deem necessary or expedient.

Jan 6, 1914