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By Walter S. Weeks

In this paper the effect of natural ventilation pressures is considered a part of the mine resistance and it is shown that their effect on the mine resistance is not the same as the total natural ventilation pressure of the shafts if the mine has several levels. It is shown that increasing the fan pressure causes the division of the air to approach the condition that would obtain if there were no natural ventilation pressure present. It is shown that if an appreciable difference in pressure is maintained between the beginning and end of a group of splits, the value of the integrated effect of the natural ventilation pressures on the individual splits does not change substantially with moderate changes of this pressure. A method is outlined for determining the resistance factor of the mine and the value of the effect of natural ventilation with the fan operating; also a method for determining this factor when circulation is caused by natural ventilation alone. Natural Ventilation Pressure Natural ventilation pressure (N.V.P.) is caused by the difference in weight of the air in two similar columns between two horizontal planes, and the difference in weight is caused principally by the difference in temperature of the two columns. The fan pressure causes some variation in density, but, since it is usually small and affects both columns, its effect is relatively unimportant. It has been suggested that "N.V.P." be called "stack effect"; but, since the term N.V.P. was used in a previous Institute paper,' applied in exactly the same manner, the term will be used. Frictional Resistance The frictional resistance to flow in a mine without natural ventilation may be expressed as RQ2 where R is a constant for a given air density and Q is the rate of flow. This frictional resistance plus the effect of velocity changes will be called the F pressure (F.P.) and a curve of F.P. against Q, the F characteristic of the mine. If a pressure is applied to a mine by a fan, the air flow so adjusts itself that the drop in pressure through any path from entrance to exit of mine, due to frictional resistances and velocity changes, is the same as that in any other path. The mine resistance varies as the square of the quantity. The air distribution without N.V.P. will be called "normal." Natural Ventilation Present When N.V.P. is irregularly distributed in a mine, it is more convenient in analysis to consider the N.V.P. as a part of the duct resistance. If it is so considered the resistance no longer varies as the square of the quantity, and if N.V.P. exists between levels the distribution of the air is no longer normal. The total N.V.P. of the mine is the pressure caused by the full length of the shafts. If a mine has several levels, N.V.P. exists

Jan 1, 1946

By Etienne A. Ritter

The Evergreen mine, located at Apex, in the northern part of Gilpin county, Colorado, has opened a very peculiar and interesting copper-deposit, in which both bornite and chalcopyrite occur as rock-minerals. The country-rocks are crystalline schists cut by dikes of granu-lite and of pegmatite. At the Evergreen property they have been cut by a dike of a uew kind of eruptive rock, to which I have given the name " Evergreenite." The rock is composed of quartz, alkali feldspars, orthoclase and albite (often interlocked as microperthite), with augite of the ægirine variety and long needles of enstatite and diallage. For reasons stated below, I believe the dike to be of Tertiary age. It is easily traced on the surface of the ground, from a point in the bottom of Pine creek, about a mile below Apex, to the top of Nevada hill, 1,500 ft. beyond and 600 ft. above it. (See Fig. 1.) It varies from 3 to 12 ft. in width, and is bounded on both sides by contact-zones about 60 ft. wide, in which the crystalline schists have been changed into pseudo-quartzites or pseudo-gneisees, according to the injection of an excess of quartz or of feldspars through the special layer of the schists. The most interesting feature is the presence of the pyroxenes, which are always found, though in very variable proportions from place to place, in the layers of these metamorphosed crystalline schists. The dike has torn from its walls a large number of fragments of the wall-rock. It must have been in a viscous state when that happened, because these fragments of the wall-rock do not show any sign of resorption or of assimilation by the magma. In places they are so distinct and so numerous that the rock looks to the naked eye like a pseudo-breccia, of which, never-

Jan 1, 1908

By C. A. Crawford

NICKEL and the nickel-copper alloy, the latter generally referred to as morel metal, are available in a variety of wrought and fabricated forums, of which the following are regular commercial products: Form Monel Metal Pure Nickel Roc Hot-rolled; round, hexagon, Same as morel metal square, and flat shapes Cold drawn; round, hexagon, square, and flat shapes Hot-rolled wire rod Cold-drawn wire rod Plates Hot-rolled Same as morel metal Sheets Hot-rolled annealed Same as morel metal Hot-rolled annealed, pickled Full-finished Full-finished, No. 3 grind one side Full-finished, No. 4 grind one side Cold-rolled (annealed) Cold-rolled, No. 5 polished finish Strip Hot-rolled (flat rods) Same as morel metal Cold-rolled (annealed) Cold-rolled (unannealed) Tubes and pipe Gas-welded tube Seamless tube Seamless tube in I. P. S. Gas-welded tube Forgings Bolts, rivets Same as morel metal Nuts and washers Forging to order Castings Sand castings Same as morel metal Centrifugal castings Electrolytic Cathodes of high purity Anodes Cast anodes Rolled anodes Shot and block for 25 to 50-1b. pigs 5, 25 and 50-1b. pigs melting. Shot Shot

Jan 1, 1927

By Walter R. Crane

PAGE I. Apparatus and Methods.......... 406 1. The Magnetic Circuit...........406 2. Apparatus Employed in the Traction-Method...... 406 a. The Coils............409 b. The Pole-Pieces..........409 3. Methods of Testing Fields Produced by Different Pole.Pices.. ..409 c. Testing with a Search.Coil........410 d. Testing with Iron-Filings and Glass Tube.. .. .410 4. General Forma of Pole-Pieces.........411 e. Flat Poles............411 f. Conical Poles........... 411 g. Spherical Poles...........411 h. Chisel-Edged (Chamfered) Poles.......412 II. Magnetic Fields...........412 5. Methods of Testinq for Magnetic Permeability...... 421 i. The Rod-Method..........423 j. Method Employed in These Experiments......424 k. Difference in the Results of the Two Methods..... 425 l. The Traction-Method.........427 m. Effect of Loosening the Charge.......430 n Corrections...........432 6. Theory.............433 o. Effect of Varying Weight on Tractive Force..... 434 p. Effect of Varying Pole-Distance.......436 q. Effect of Varying Magnetization.......436 T. Effect of Varying Size.. .......437 a. Summary,........... 441 III. The Relative Magnetic Permeability of Various Minerals,. 443 The form and strength of magnetic fields have attracted much attention. especially in connection with the designing of dynamo-electric machinery—an art which has been revolution-

Jan 1, 1902

By Morris Cohen

This paper deals with the calculation of the composition of the infinitesimal trace of alloy that transfers from the liquid to the solid state at each temperature during the equilibrium solidification of a binary solid solution, and which thereby enables the compositions of the coexisting liquid and solid phases to follow along the liquidus and solidus lines respectively during the cooling. A general expression for the composition (S) of the liquid-to-solid transfer at each temperature has been derived S - ZLXL(XL - P) + Zsxs(P - XS) ZL(xL - P) + Zs(P - XS) where ZL and Zs are the slopes of the liquidus and solidus lines at the given temperature, XL and xs are the composi-tions of the stable liquid and solid phases at the same temperature, and P is the composition of the alloy under considera-tion. The S equation is valid for the process of equilibrium heating as well as cooling, and may be applied to vapor-to-liquid, vapor-to-solid, liquid-to-liquid, and solid-to-solid transfers if the corresponding equilibrium diagrams are known.

Jan 1, 1940

By Frederick Laist, H. J. Maguire

The ore from the Butte mines of the Anaconda company is quite siliceous; that is, it contains considerably less iron than is needed for the fluxing of the silica. The direct smelting of this ore, therefore, requires the addition of considerable fluxing material. The only flux available in sufficient quantity at Anaconda is limestone containing no metallic minerals. This necessarily makes the direct smelting of the ore so expensive that it is more profitable to subject the ore to a preliminary treatment by concentration. However, as the losses in the concentrator were very high, compared with the losses in the blast furnaccs, it was found, by calculation, more profitable to send ores containing more than a given percentage of copper to the blast furnaces, in spite of the higher costs of treatment. The dividing point was dependent on various factors, the chief of which was the prevailing market price of copper. It was customary, therefore, to segregate the ore as mined into two classes. Ore in the first class generally contained 5 per cent. or over of copper; this was sent directly to the blast-furnace department. Second-class ore contained less than 5 per cent. of copper, and averaged around 3 per cent.; it went to the concentrating department. With the introduction of the flotation process, it mas found possible to maintain an average recovery, as concentrates, of 96 per cent. At the same time, the cost of reverberatory smelting was very materially decreased by the use of pulverized coal. These two changes in practice made the blast furnaces unable to compete with the reverberatory furnaces on a cost basis. The distinction between first- and second-class ore was therefore abandoned, and the ore was treated by concentration. Obviously, on ores as high in iron as the Butte ores, the concentrator produces a product that is self-fluxing; in fact, it is possible to produce a concentrate containing more iron than is necessary to flux the silica. Under these conditions, the amount of basic fluxing materials required for the smelting operations became very srnall and the converter slag lost its former value as a blast-furnace flux. For this reason, a less expensive method of recovering the copper, silver, and gold contained in it than smelting in blast furnaces had to be found. It was not feasible

Jan 1, 1921

By L. O. Howard

Much work has been done recently on the lead-antimony system' in connection with lead-rich alloys of commercial importance containing less than 20 per cent. antimony. Dean, Zickrick and Nix have called attention to the perpetuation in the literature of several erroneous data, such as a eutectic temperature of 228° C. at 12.5 per cent. antimony, instead of 247° at 13 per cent. The series is given as a classic example of a straight eutectiferous series in such late books as those of Heyn and Grossmann,2 Jeffries and Archer,3 Guillet and Portevin,4 Pulsifer,5 Rosenhain,6 and Liddell,7 as well as the somewhat earlier works of Hofman (1918), Wang (1909), and Williams (1920). The work of Dean has definitely shown a solid solution of antimony in lead at about 2.5 per cent. antimony. While lecturing to a class in general metallurgy at the University of Idaho, the writer had the students prepare a series of lead-antimony alloys for the purpose of illustrating methods of thermal analysis. Proper proportions of powdered antimony (sold as C.P.) and. test lead were mixed and melted in graphite crucibles under a reducing cover. Cooling

Jan 1, 1928

By Frank Firmstone

The indicator cards shown herewith were taken by the writer in June, 1877, from the water-pressure blowing engine of the Longdale Iron Co., at Lucy Selina Furnace, Longdale, Virginia. A description of' this engine with figures, and some indicator cards, was published by Washington Jones, Esq., Superintendent of the I. P. Morris Co.,* in the Journal of the Franklin Institute for May, 1877, to which those desiring a full account are referred, but for convenience the principal dimensions, etc., are given below. The machine consists of a pair of horizontal direct-acting blowing engines, connected at right angles to a common fly-wheel shaft. The blowing cylinders are 4 ft. diameter by 5 ft. stroke; the water cylinders were 18 in. diameter by 5 ft. stroke as built. Both water and blowing cylinders are double acting. The water valves are balanced piston valves, 18 in. diameter, moved directly by eccentrics on the fly-wheel- shaft. Great care was taken to have the areas of the ports and passages at least equal to the area of the working piston. The engine is set about 14 ft. above the tail-race, and the

Jan 1, 1879

By L. O. Howard

Much work has been done recently on the lead-antimony system1 in connection with lead-rich alloys of commercial importance containing less than 20 per cent. antimony. Dean, Zickrick and Nix have called attention to the perpetuation in the literature of several erroneous data, such as a eutectic temperature of 228° C. at 12.5 per cent. antimony, instead of 247° at 13 per cent. The series is given as a classic example of a straight eutectiferous series in such late books as those of Heyn and Grossmann, 2 Jeffries and Archer,3 Guillet and Portevin,4 Pulsifer,5 Rosenhain,6 and Liddell,' as well as the somewhat earlier works of Hof-man (1918), Wang (1909), and Williams (1920). The work of Dean has definitely shown a solid solution of antimony in lead at about 2.5 per cent. antimony. While lecturing to a class in general metallurgy at the University of Idaho, the writer had the students prepare a series of lead-antimony alloys for the purpose of illustrating methods of thermal analysis. Proper proportions of powdered antimony (sold as C.P.) and test lead were mixed and melted in graphite crucibles under a reducing cover. Cooling

Carlisle: Jim Knapp, has been the good friend of hundreds-maybe thousands-of mining men in these western states in the last 40 or 50 years. Jim is going to talk about many of the mining camps of Nevada, where he has done plenty in the mining field during the last 50 years. Jim, for a starter, how did you happen to go to Nevada? Knapp: In the summer of 1902, two years after the discovery at Tonopah, the professor of mining at Stanford sent out myself and another student by the name of Joe Miller to make a report on the camp. We left San Francisco at 8 p.m., got to Reno the next morning, then took the train to Sodaville, arriving about 4:30 in the afternoon. The first man I met when I arrived at the Tonopah station was Tasker Oddie, a gentleman who later became the Govenor of the State and then a United States Senator. Before we got away from the stage station I also met S. H. Brady, the first mining engineer to put out his shingle in Tonopah. He afterwards became general manager of the West End Mining Co.

Jan 3, 1965

By L. O. Howard

MUCH work has been done recently on the lead-antimony system1 in connection with lead-rich alloys of commercial importance containing less than 20 per cent. antimony. Dean, Zickrick and Nix have called attention to the perpetuation in the literature of several erroneous data, such as a eutectic temperature of 228° C. at 12.5 per cent. antimony, instead of 247° at 13 per cent. The series is given as a classic example of a straight eutectiferous series in such late books as those of Heyn and Grossmann,2 Jeffries and Archer,3 Guillet and Portevin4 Pulsifer,5 Rosenhain,6 and Liddell,7 as well as the somewhat earlier works of Hofman (1918), Wang (1909) and Williams (1920). The work of Dean has definitely showed a solid solution of antimony in lead at about 2.5 per cent. antimony. While lecturing to a class in general metallurgy at the University of Idaho, the writer had the students prepare a series of lead-antimony alloys for the purpose of illustrating methods of thermal analysis. Proper proportions of powdered antimony (sold as C.P.) and test lead were mixed and melted in graphite crucibles under a reducing cover. Cooling

Jan 1, 1928

By J. R. Finlay

The Cæur d'Alene silver-lead mining district of northern Idaho is probably best known to the general public as a seat of labor-troubles. So far as the writer is aware, little has been written and little is known about its geology and resources. People interested in lead-smelting are, of course, cognizant of the economic importance of the region, but they have not communicated much of their knowledge to the public. Exact figures as to the total output of the district are not obtainable, but the following estimates, covering the entire output of the 15 years during which the mines have been operated, are believed to be approximately correct: Group of Mines. Product. Wardner Group, including the Bunker Hill and Sul livan, Empire State-Idaho, Last Chance, Sierra Nevada, bur d'Alene Development Co... . $17,500,000 Cafion Creek Group, including the Gem, Frisco Con solidated, Granite, Standard, Mammoth, Hecla, Tiger-Poorman, Custer and Bell,.... 35,000,000 Mullan Group, including the Morning, You Like and Gold Hunter,........7,500,000 $60,000,000 This output covers the period of discovery and early struggles, and several periods of stagnation caused by strikes and other serious labor-troubles. In 1900 the output of the district was fully $10,000,000, and this figure would have been considerably increased in 1901 had not a curtailment of production been forced by the condition of the lead-market. In 1901 the product was about 150,000 tons of concentrates, with a gross. value of $8,250,000.

Jan 1, 1903

The accompanying sketch shows the interesting position of Salt Lake City with reference to Western mining areas and justifies its title "The Center of Western Mining." In the last twenty years, the area embraced within a circle of 600 miles radius with Salt Lake City as its center has produced 79.87% of the gold, 91.9% of the Silver, 77.47% of the copper, 53.61% of the lead and 26.55% of the zinc produced in the United States, including Alaska. This area also contains the greatest coal deposits of the continent, some of the greatest oil deposits, great iron deposits and many other important mineral resources. The 600-mile circle contained 69% of the active operators of other than coal mines and 40% of the men employed in mines other than coal mines of the United States, including Alaska, for the four-year period ended with 1923.

Jan 1, 1925

The Industrial Minerals Division met jointly with the Materials and Equipment Division of the American Ceramic Society at State College, Pa, Sept 24-26 Headquarters were at the Nittany Lion Inn Thurs- day afternoon was devoted to a tour of inspection of the Bell Mine, American Lime and Stone Co , Bellefonte, Pa The party returned to State College for dinner and in the evening the Division's executive committee held a brief session There were four technical sessions Friday morning, Mining, afternoon, Beneficiation, Saturday morning, Industrial Minerals and Beneficiation There was an informal banquet at the Nittany Lion Inn Friday night with 93 present Edward Steidle was toastmaster Brief talks were made by President F C Flint and Secretary Ross Purdy, of the American Ceramic Society, Oliver Bowles, Chairman, Industrial Minerals Division, Adrian Morse, assistant to the president, Pennsylvania State College, and George Otis Smith, past president A I R'I E

Jan 1, 1937

By Henry Mulryan

THE largest and purest known deposit of diatomite is being actively mined and processed 3 ½ miles south of Lompoc, Santa Barbara County, Calif., by the Johns-Manville Products Corporation. The workings FIG. 1-LOCATION OF DIATOMITE DEPOSIT AT LOMPOC. cover 4000 acres, the depth of economically recoverable diatomite being 1000 ft. (Fig. 1). Lompoc, a community of 2500 population, is situated in the Santa Ynez River Valley 10 miles inland from the Pacific Ocean. It is 44 miles

Jan 1, 1936

By Robert Ammon

THE purpose of this paper is to present a brief sketch of the development of this hindered-settling classifier, but primarily to show the actual results obtained in practice with the classifier working on the Butte copper ores at the Boston & Montana Concentrator, at Great Falls and the Washoe Concentrator at Anaconda. The writer has endeavored to be as brief as possible, giving only the essential figures showing the efficiency of the classifier and leaving considerable interesting information to be derived by the reader from the statistics given. The paper deals with the practical work of the classifier under the following heads: 1. Desliming 4.0-mm. primary feed, overflow from 0.07 to 0.0 mm. 2. Desliming 1.25-mm. secondary feed, overflow from 0.07 to 0.0 nun. 3. Desliming Huntington Mill discharge, overflow from 0.07 to 0.0 mm. 4. Classifying 2.5-mm. deslimed secondary feed, overflow from 1.00 to 0.07 mm. 5. Classifying 2.5-mm. deslimed primary feed, overflow from 0.75 to 0.07 mm. 6. Classifying 4.0-mm. deslimed primary feed, overflow from 0.75 to 0.07 mm. 7. Classifying middling-tailing product from roughing tables, overflow coarse tailing. 8. Classifying 2.5-mm. trommel undersize, not deslimed, overflow from 0.75 to 0.0mm. 9. Remarks on the inner feel cone. In the following pages all overflows, are given in quartz dimensions; i.e., by a 0.75-mm. overflow 'is meant an overflow whose maximum particle is a 0.75-mm. quartz grain. By the term "slime" is meant all material which will pass through a 200-mesh screen whose average opening is 0.07 mm.

Jan 8, 1913

By C. E. Sims, H. M. Banta, S. L. Hoyt

Over the past few years, metallic arc welding has been extended to steels of the hardenable type. As compared with other methods of fabrication, production has been facilitated, service performance frequently has been improved, and the overall results have been so favorable that engineers and production men have placed great emphasis on this application of welding. The metallurgist and welding engineer, however, have been confronted with new problems, since, for one reason, the harder steels are more apt to crack and special precautions must be taken if sound joints are to be procured. Some of the factors that are pertinent to this problem are metallurgical, and it is an object of this contribution to discuss steel manufacture and processing methods and to show how their control assists in reducing the hazard of cracking. By this time, the problem of cracking— specifically underbead cracking, or "hard cracks," or parent-metal cracks-—is well known, and a large amount of work has been published, both here and abroad, dealing with this subject.' The tests described are made under restraint to facilitate cracking and arc so designed that a semiquantitative, or at least a relative, value of the cracking tendency is obtained. As one would expect, it has been reported that the incidence of cracking increases with the carbon and alloy content of the steel. More specifically, the cracking tendency is said to increase with the hardenability of the steel, though it is now recognized that the situation is not so simple. The phenomenon itself, on the other hand, has been but loosely described, and it is in only broad generalizations that this cracking has been related to steel metallurgy. Thus, while it has been abundantly demonstrated that the hardenable aircraft steel, S.A.E. 4130, must tend to crack when are-welded, the problem still remains of why two lots of the same composition and the same hardenability can vary so greatly in cracking tendency, or what it is about the prior metallurgical history that so strongly affects the results. Further, while the efficacy of preheating and postheating in preventing cracking is recognized and utilized in production, the mechanism by which they function seems not to have been described. These points are thought to be significant in the production of steel for fabrication by metallic arc welding and, hence, of interest to mill and process metallurgists and welding engineers. Consequently, it is another object of this paper to discuss the mechanism of parent-metal cracking, including the influence of the condition of the steel and the control of cracking by manipulation of the time-temperature conditions during and after welding. A new method of rating the cracking tendency is also discussed, and the results of the test are related to steel composition and structure or prior history. The work to be described was the outgrowth of work in 1940-41 at Battelle Memorial Institutc on two projects, one

Jan 1, 1945

By A. R. Troiano, E. A. Steigerwald, F. W. Schaller

The initiation of localized cracking in hydrogenated high strength steel was dependent on the developmeni of a critical hydrogen conceniration and relatively insensitive to the magnitude of the applied stress. The stress was believed to influence the deluyed failure process by providing the means for grouping the hydrogen. On the basis of an assumed distribution law the observed changes in the lower critical stress as a function of notch acuity, yield strength, and temperature were predictable over a significant range of these variables. THE phenomenological characteristics of delayed failure in high-strength steel have been comprehensively investigated and the behavior has been attributed to the strong embrittling action of hydrogen.1-3 Delayed failure or, as it is also termed, static fatigue, is the most sensitive means of detecting hydrogen embrittlement since it allows the maximum time for hydrogen diffusion during a test.3 The nature of delayed failure cail be aptly described by four parameters which are schematically depicted in Fig. 1. The upper critical stress corresponds to the rupture stress in a conventional notch tensile test. The lower critical stress or static fatigue limit is the stress below which no delayed failure will occur. The incubation period is the time required for the formation of the first crack and the fourth parameter is the failure time. An increase in hydrogen content, notch acuity, or strength level of the material increases the susceptibility for delayed failure by decreasing the lower critical stress, the incubation period, and the time to failure.lY3 A decrease in test temperature prolongs the incubation period in accordance with the lower diffusion rate of hydrogen, and also de-

Jan 1, 1961

By Richard Akerman

At the International Sessions of the Iron and Steel Institute of Great Britain, the American Institute of Mining Engineers and the Verein Deutscher EisenhUttenleute, held in Allegheny City, Pa., in October, 1890, Sir James Kitson, then President of the Iron and Steel Institute, presented an account by Sir Henry Bessemer of the origin of the process which bears his name.? The paper graplhically told how, after the first successes immediately following the first reports given at Cheltenham of the new process, there rapidly succceded such obstacles and difficulties in its practical application, that the whole matter was nearly abandoned in 1858. Suddenly, however, the situation changed, so that at length it became possible

Jan 1, 1894

By K. Osseo-Asare

The DIAGRAM computer program has been used to develop stability diagrams such as Eh-pH, log [CNI-pH, and log [Me]-pH for the systems Me-CN-H 0 where Me = Au, Ag, Fe, Zn, Cu, Ni, Co. More complex 2 diagrams involving sulfur- and arsenic-containing species are also presented. With the aid of these diagrams, a discussion is presented of the solution conditions (e.g. pH, [CN], [CNS], Eh) vhich influence gold and silver extraction in cyanide solutions. Special emphasis is given to the effects of ore minerals or calcination products, such as pyrrhotite, pyrite, arsenopyrite and hematite on gold-silver dissolution. Application of the stability diagrams to solution treatment operations such as cementation is also indicated.

Jan 1, 1984