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By Carls Benedicks

It is well known by every one who has had to deal with boiler tubes that these are often seriously affected by a sort of corrosion, occurring as a local pitting, that frequently causes a perforation of the tube in a rather short time. The characteristic appearance of this corrosion is shown in Fig. 1. A very similar corrosion occurs in condenser tubes (Fig. 2).l A study of the microstructure or local chemical composition of the metal (iron 70:30 brass) fails to reveal any cause for this pitting. Of course one might possibly assume the starting point to be some oxide particle, causing an electrolytic local action, but this in no way explains the continued corrosion, progressing even when the assumed oxide particle must have disappeared. By the excellent work done by the Corrosion Research Committee of the Institute of Metals, and communicated, in October, 1923, to the Institution of Engineers and Shipbuilders in Newcastle-on-tyne, stress was laid on the faot that a content of entangled air has a very obnoxious effect. In the following correspondence, Sir George Goodwin stated that "engineers have, for a long time past, regarded air as the big enemy to be fought against in all questions of corrosion'72 and Kenneth Fraser pointed out that the most vital point is "the avoidance or removal of possibly the chief cause of present day corrosion, i. e. entrapped air and gases brought out of solution."3 In their reply, however, the authors state that they had "never for a moment believed that entangled air was responsible for the beginnings of corrosion, and express the opinion that the gradual liberation of air could not account for localized corro~ion."~ On consulting the many textbooks on corrosion, as that

Jan 1, 1925

By H. S. Fleming

My original intention was to give a full account of Southern furnaces, ores and cokes; but, owing to the difficulty of getting reliable information, I confine this paper to a general description of the ores used in, and immediately around, Chattanooga. Mr. L. S. Colyar, Manager of the Rising Fawn furnace, wrote me in answer to an inquiry as to what ores they were using, " Below I give you analyses of the mixture of ore we have been using for the past seven or eight years. We haven't a complete analysis of any ores, but I will give them to you as I have them. Attalla Soft Rising Fawn Hard Rising Fawn Red Ore. Red Ore. Soft Ore. Iron,.... 50.60 38.48 46.82 Silica,. .. 11.69 7.32 22.69 Phosphorus,. .. 1.06 .319 .350 This is a fair average of all the ores we get in this section." The following analyses of Birmingham soft ore were received from the Morris Mining Co., of that place. No. 1. NO. 2. No. 3. No. 4. Iron.....51.60 54.88 51.04 51.20 Silica,. .. 19.32 10.60 17.32 17.08 Alumina,....19 .88 1.18 Phosphorus,. ..129 .287 .116 .464 Mine No. 1, second vein, shows: iron, 46.40; alumina, 4.92; phosphorus,.212; silica, 19.60. Mine No. 1, by analyses obtained from the Mary Pratt Furnace CO., shows: Iron. Silica. Fine red ore,.49.00 18.38 Lump red ore,...54.42 17.10 Bottom vein,.50.00 21.38 Bottom vein,.41.24 13.52 A lot of this ore delivered in Chattanooga gave : iron, 53.32; alumina, 2.10; phosphorus,.529; silica, 18.03.

Jan 1, 1887

By Hobart M. Kraner

THE mineralogy of blast furnace sinter is of interest because its mineral content is one of the important factors contributing to its character. There are so many other factors affecting the properties of the sinter, however, that it is well to mention them here. The proportion and character of the raw materials, that is, raw ores, concentrates, returns, and fuel, as well as the mixing and the water content, all have a marked effect on the physical properties of the product and the degree to which sintering action can be carried on. The process of sintering is a relatively fast operation. In as much as appreciable time is required to carry on processes of fusion in such masses of low thermal conductivity, large lumps of hematite ore frequently remain unfused and partly unchanged in state of oxidation in the sintering process. The kind, the grain size, and the amount of fuel used affect both the completeness of the fluxing reaction and the prevailing atmosphere. The rate of reduction in laboratory tests is not only dependent upon the state of oxidation of the sinter but also upon the sizing and porosity. Atmosphere and temperature affect the state of oxidation of the iron oxide, and the atmosphere alone may determine the ferrous minerals that finally develop. The rate and extent of cooling, the type of coolant, the subsequent handling, and screening all have serious effects upon the type of sinter that eventually enters blast furnace bins. The degree to which actual fusion or fluxing takes place in the sintering operation has a marked effect upon density. A sinter which has been extensively fused by high content of fuel in the batch will no doubt have a higher weight on the bulk basis than one which had a lower fuel content. As high temperatures are required to do this job, the iron oxide under these conditions will be largely magnetite. Sintering at low temperatures to produce larger proportions of hematite means a decrease in the amount of liquid formed and a much more sensitive bonding process. In this case the liquid must be distributed more uniformly and thereby used more efficiently than would be the case where higher temperatures were permitted to prevail more or less indiscriminately. Where coarse ore particles are used in a sinter mix it is not expected that any particles coarser than 1/4-in. can be fused and incorporated in the system to such an extent that the gangue contained within these lumps will have been converted or fused by the sintering process. It is for this reason that coarse ore, returns, or both, in a sinter usually result in a sinter which breaks easily and at the same time may contain some of the original minerals of the lump, such as quartz and hematite. In examination of sinters at Bethlehem Steel Co. minerals such as quartz and corundum have been found, none of which are considered normal associ- ates of wustite or magnetite. Some degree of heterogeneity or lack of equilibrium is not unusual in the sintering process. The differences in specific gravity between hematite and magnetite might be ample reason for poor strength in a not very well sintered mass containing coarse particles of. ore or returns. The shrinkage taking place in a lump of hematite in its conversion to magnetite by temperature and/or atmosphere is appreciable. Sintering of ores as it is carried out is crude chemistry, for the grain size is relatively coarse, the application of heat is certainly not uniform, and the time factor is inadequate for other than partial completion of reactions. Coarse lumps of coke or coal cause local heating around these centers, and fuel which is too fine may result in such slow burning that sufficiently high temperatures are not always obtained. High temperatures are essential to the work required. The Swedish practice of sintering is established on the basis of producing an easily reducible product high in hematite. This is achieved through uniformity of grain size in the sinter mix and close control of the temperature through careful regulation of fuel and sintering rates. This produces a sinter which is very tough in character and which has a high degree of porosity. Although the hematite content is not produced upon cooling by drawing air through the mass, there would be greater possibility of accomplishing this reaction with this type of sinter than is the case in American practice. In the latter, the temperatures are so high that temperature alone converts most of the mass to magnetite. The grains are so coarse in the final product that together with the fluxed condition it would be difficult to reoxidize them to hematite upon cooling. An examination of the iron-oxygen diagram' shows that hematite does not exist above 2651°F. It also shows that there is no liquid in the pure magnetite-hematite system until 2881°F is reached. On the other hand, in the system magnetite-wustite liquids exist at considerably lower temperatures than this. It will be seen, therefore, considering only the iron oxides, that the bonding action obtained in America in sinters comes about through considerable temperature and/or reducing conditions that produce compositions containing even less oxygen than is contained in magnetite or than results from the fusion of silicates. The bonding obtained from the iron oxides is encouraged by the reducing conditions that prevail in the vicinity of the fuel particles in a mass of this sort, where temperatures are above 2600°F. As magnetite and wustite are opaque, they do not lend themselves to petrographic study by transmitted polarized light. The silicates found in sinter and the glass that has not crystallized transmit light and can be studied by these methods in which indices of refraction and other optical properties of anisotropic crystals lead to their definite identification. The index of refraction is the only property that can be measured in glass under the microscope, and this is a clue to its probable approximate composition.

Jan 1, 1954

By W. L. Connell, O&apos

The properties of some heavy liquids which can be used in sink-float separations are discussed with major emphasis being given to the halogenated hydrocarbons. Data are presented on density, viscosity, thermal characteristics and the effects of moisture and temperature on the corrosiveness of the liquids towards various materials of construction. The toxicity of these materials, the hazards involved in handling them, and the procedures for handling them safely are also discussed. True liquids have certain advantages over colloidal suspensions for sink-float separation of minerals which makes their use especially advantageous when close separations, fine particle sizes or water-soluble minerals are to be treated. For best separating results, the medium should have an easily controlled, uniform, stable density. Here, true liquids have the advantages of allowing closer control of density and of not requiring agitation to maintain a uniform den- sity in the equipment. Low viscosities are desired in a separating liquid so that rapid separations of fine material can be made. Many liquids have lower viscosities than the colloidal suspensions at operating gravities of 1.4 to 5.0. For economic reasons and to prevent contamination of the product, the separating medium must be easily and completely removed from the ore. Normally, true liquids must be more completely removed than the cheaper suspensions and thus cause more problems in this area. The fact that the medium should not react with the minerals, air, water or the common materials of construction limits the choice of liquids which can be used, but many are available which are sufficiently stable. A more serious objection to the use of true liquids is that many of them present a toxic hazard to operating personnel and users of the product. Most true liquids are toxic to some extent, but modem knowledge of toxicity allows us to recognize the hazards inherent in handling them and enables us to design around them. Three types of true liquids are available for this use: 1) Halogenated hydrocarbons cover the gravity range from 1.2 to 3.3. They are generally more volatile and less viscous than the other liquids.

Jan 1, 1963

By AIME AIME

AN unusual interest in the question of orienting the young college man in the mineral industry was shown in a well-attended session* of the Engineering Education Committee on Monday afternoon. About seventy-five employers and educators of mining engineers were present and took part in the discussions.

Jan 1, 1929

By F. W. Jessen, G. F. Sears

Cavities in massive salt for the purpose of storage of liquid hydrocarbons have assumed a prominent position in recent years. This paper describes a program to facilitate leaching operations for the formation of specifically shaped storage cavities. Various forms and sizes of cavities may be possible through use of the techniques developed. INTRODUCTION The creation of large under ground storage facilities for natural gas and liquified petroleum gases has been practiced for many years. Use of cavities obtained through solution of salt for this purpose is a fairly new and novel approach, but has gained increasing importance due mainly to the economics of this type of mining operation opposed to hard rock mining or surface and pit storage.1 The idea of controlling the shape of any cavity dissolved from massive salt has not been a prime consideration of companies engaged in the formation of storage space. This has been due mainly to an insufficient knowledge of the mechanics of the leaching process and a dearth of published information dealing with both the desirability and ease of control possible for this type of operation. Two distinct advantages are readily ascertainable. From a stability standpoint (i.e., the ability of the completed cavity to withstand stress imposed by overburden pressure and lateral tectonic stresses) a controlled cavity may be generated which will yield the most favorable attitude to these external forces and remain in operable use for longer periods of time.2 A second advantage is that for a given volume, a sphere (which is one controlIed shape possible) represents the minimum surface area exposed. This may become more important in the future when dealing with refrigeration and product losses in underground cavities. The basic solution mining process, without regard for controlling the final shape, is quite simple in that the equipment and materials required to dissolve a cavity in a salt dome or layered salt section are a source of fresh water, a circulating pump, several strings of tubing and a means of disposal of the return brine. To add control measures involves the use of an inert blanket material above the position at which solution proceeds. Initially the annulus of the largest wash pipe is filled with this blanket down to the top of the proposed cavity. The bottom of the proposed cavity is determined by the depth of the original drilled hole or a blanking plug. The blanket material is added incrementally in stages and displaces the water in the enlarging cavity downward. Where the blanket material has displaced the water, no further solution takes place. The rate at which to add this controlling blanket material so as to be able to form specifically shaped cavities of any particular size is of considerable importance. THE PROBLEM It is desirable to have as much information as possible as to the behavior of the mining operation since visual observation obviously is impossible. It would be advantageous, for example, to have a step-by-step program showing how much salt is to be removed, at what rate and the time required. This type of program would facilitate procurement of surface equipment and provide for proper management of manpower requirements, as well as yield a host of intangible benefits. As mentioned earlier, only rule-of-thumb estimates were available until recently and made this type of pre-planned operation haphazardous at best. Recent work3-' has done much to clear up the ambiguities and inaccuracies attendant to solution mining of salt and has helped to place the operation on a more scientific basis. This study attempts to correlate much of the information thus far developed into a complete mining program; to extend the idea of controlled solution mining to include not only spheres, but solid conic sections of the ellipsoidal variety; and to refine the computation of the rate of removal of salt during the various stages of mining. Dommers3 and IIemson4 made extensive laboratory

Jan 1, 1967

By B. M. Loring, I. R. Krame, F. M. Walters

NO observations on the mechanical properties of man-manganese alloys have been published since pure manganese became readily available, either distilled manganese or electrolytic manganese. The purpose of this investigation was to determine whether iron-manganese alloys are essentially brittle, as reported by Hadfield,' or whether the lack of ductility observed was due to impurities in the alloys that he studied. Experimental Methods The alloys were melted in a roo-lb. high-frequency induction furnace with a magnesia crucible, using ingot iron and electrolytic manganese. The heats were split, the first giving six 18-lb, ingots and the second three. Each successive heat was higher in manganese and about 0.3 per cent silicon was added as ferrosilicon. The alloys forged without difficulty and were given a 9' per Published by permission of the Navy Department. Manuscript received at the office of the Institute June 28. 1941. Issued as T.P. 1369 in Metals Technology. September 1941. * Division of Physical Metallfirgy Naval Roscarch Laboratory. Anacostia Station Washington. D. C. 1 References are at the end of the paper. 4 cent reduction to ¾-in. rounds. The chemical analysis of the alloys is given in Table I. The forged rods were homogenized for 224 hr. at r150°C. (2100°F.) and air-cooled. The alloys were tested in two conditions of heat-treatment: (I) as normalized from 870°C. (1600°F.) and (2) normalized from 870°C. and tempered for I hr. at 540°C. (Iooo°F.) and air-cooled. The tensils specimens were 0.505 in. in diameter with a 2-in. gauge length, and the impact specimens were v-notch Charpy. The proportional limit and yield strength were taken from the stress-strain diagrams drawn by a Peters recorder. The data obtained from the tensile test and the hardness measurements are given in Table 2. Specimens that were normalized are designated by N; those that were normalized and tempered by T. Alloy G was tempered after forging (D).

Jan 1, 1942

By B. M. Loring, I. R. Krame, F. M. Walters

NO observations on the mechanical properties of man-manganese alloys have been published since pure manganese became readily available, either distilled manganese or electrolytic manganese. The purpose of this investigation was to determine whether iron-manganese alloys are essentially brittle, as reported by Hadfield,' or whether the lack of ductility observed was due to impurities in the alloys that he studied. Experimental Methods The alloys were melted in a roo-lb. high-frequency induction furnace with a magnesia crucible, using ingot iron and electrolytic manganese. The heats were split, the first giving six 18-lb, ingots and the second three. Each successive heat was higher in manganese and about 0.3 per cent silicon was added as ferrosilicon. The alloys forged without difficulty and were given a 9' per Published by permission of the Navy Department. Manuscript received at the office of the Institute June 28. 1941. Issued as T.P. 1369 in Metals Technology. September 1941. * Division of Physical Metallfirgy Naval Roscarch Laboratory. Anacostia Station Washington. D. C. 1 References are at the end of the paper. 4 cent reduction to ¾-in. rounds. The chemical analysis of the alloys is given in Table I. The forged rods were homogenized for 224 hr. at r150°C. (2100°F.) and air-cooled. The alloys were tested in two conditions of heat-treatment: (I) as normalized from 870°C. (1600°F.) and (2) normalized from 870°C. and tempered for I hr. at 540°C. (Iooo°F.) and air-cooled. The tensils specimens were 0.505 in. in diameter with a 2-in. gauge length, and the impact specimens were v-notch Charpy. The proportional limit and yield strength were taken from the stress-strain diagrams drawn by a Peters recorder. The data obtained from the tensile test and the hardness measurements are given in Table 2. Specimens that were normalized are designated by N; those that were normalized and tempered by T. Alloy G was tempered after forging (D).

Jan 1, 1942

By H. Stigzelius

FINLAND'S recent mining history is both dramatic and pitiful in its shifting fortunes, dominated as it has been, by the country's proximity to the border zone of opposing dictatorships and social traditions; Fascism to the south, Communism to the east, and Democracy to the west. After 108 years under Russia's more or less harsh rule, Finland gained its democratic independence during the 1917 revolutionary strife in Russia with the official help of Germany and spontaneous help of other neighbors. The young nation was attacked by Russia in 1939 and again in 1941. It is common knowledge how the Finns fought with everything they had and everything they could get against their overwhelming adversary, and how by force of circumstances they landed in the Axis camp in 1941. Finland has never been known as a mining country in the same way as near-by Sweden, whose abundant iron and copper smelters during long periods so greatly contributed to the nation's welfare. Its largely barren, Archaean-granite geology long seemed forbidding. Some mining was done, to be sure; copper and tin at Pitkaranta near the Russian border, and lead and copper at Orijarvi. But towards the end of the last century the absence of a single producing mine cast a pessimistic shadow of truth over the Finnish poet Runeberg's words, that

Jan 1, 1946

By R. K. Buhr, H. Thresh, M. Bergeron, F. Weinberg

The microsegregation of nickel and chromium in directionally solidified AISI 4340 steel castings has been measured using electron probe microanalysis. Minimum concentrations were observed to occur at the center of the dendrite stalks, as reported previously. However, the position of the maximum concentrations could not be determined from the dendrite configuration. An etching technique has been developed which shows the position of maximum concentration. Measurements were made of the distribution of nickel and chromium in the dendritic structure. The ratio of maximum to minimum concentration was determined as a function of primary dendrite arm spacing for both as-cast and partially homogenized materials. The results are compared with observations reported in the literatuve. A S part of an investigation of solute segregation in directionally solidified AISI 4340 steel casting, electron probe microanalysis was used to measure the distribution of nickel and chromium in the dendritically segregated material. This complemented the observations on the segregation of radioactive phosphorus obtained by autoradiographic techniques in the same castings.' Kattamis and I?lemings2 have reported similar measurements, using electron probe microanalysis, on dendritically segregated AISI 4340 steels. They found minimum solute concentrations occurred at the center of dendrites, maximum concentrations occurred in the center of interdendritic regions, for symmetrically oriented dendrites, and a regular variation of concentration within dendrite arms. The ratio of maximum to minimum concentration was found to be essentially independent of position in the castings, except near the chill surface where it was somewhat higher. Assuming complete diffusion in the liquid and no diffusion in the solid during freezing, they considered that isoconcentration curves in the steel were homothetic. As a result, isoconcentration curves of the various elements, contour surfaces of dendrites produced by isothermal-transformation studies, and the contour of the solid-liquid interface would all be similar, and could be superimposed by a uniform expansion or contraction of the contours. Preliminary results of the present investigation suggested that isoconcentration curves were not homothetic. It was also evident that points of maximum concentration could not be predicted from the dendrite configuration. Since the ratio of maximum to minimum concentration appeared to be an important parameter in defining the overall segregation in a casting, other techniques for determining the point of maximum concentration were investigated. In addition the overall solute distribution associated with the dendritic structure was examined for both nickel and chromium, and the consistency of the distribution for neighboring dendrites was determined. METHOD Fifty-pound heats of AISI 4340 steel were cast in a manner similar to that used by Flemings et al3 with a water-cooled copper base plate and exothermic sides and top. The nominal composition of the material was C, 0.41 pct; Mn, 0.66; Si, 0.35; S, 0.012; P, 0.010; Ni, 1.88; Cr, 0.95; Mo, 0.28. The steel solidified directionally from the chill surface, with a dendritic structure which increased in dendrite arm spacing with increased distance from the chill. Results of the general investigation of the cast structure and segregation of radioactive phosphorus in these castings have been reported elsewhere.' For the present measurements, sections were cut from the casting at several distances from the chill surface. The sections were subsequently heat-treated, mounted, and then polished on a plane perpendicular to the general freezing direction of the casting. Electron probe microanalysis was carried out with the JEOL-JXA3 microprobe using a voltage of 25 kev and beam current of 0.15 µa. The take-off angle is 22 deg. Quartz crystals were used in the spectrometers and measurements made for Ka radiation from both nickel and chromium simultaneously. A thin layer of carbon was deposited on all specimen surfaces prior to examination in the microprobe. Early measurements were made on polished surfaces, with indentation marks produced by a hardness tester to indicate the area of interest. It was found desirable to use etched surfaces, as opposed to polished surfaces, to reduce sample preparation time and more readily relate the microprobe scan to the structure. To determine if this could be done, without introducing significant errors, a series of measurements were made on polished and etched surfaces of the same specimen. Both polished and etched surfaces produced similar results within normal scatter as shown in the observations. Subsequent measurements were then made on etched surfaces. Measurements with the microprobe analyzer were made by point counting, for periods of 100 sec, at 10-µ intervals. Ten-second counts were made on pure nickel and chromium standards, incorporated in the specimen mount before and after each set of measurements. The results were adjusted for background, then corrected for dead time using the expression:

Jan 1, 1969

By W. E. C. Coxe

AT the meeting of the Institute in Philadelphia, in June, 1876, it was my pleasure to read a paper on the "Manufacture and Endurance of Iron Rails." I then spoke of some trial rails which had been placed in the down track of the Philadelphia and Reading Railroad, over which passed, in addition to merchandise and passengers, most of the heavy coal traffic of that company. One of these rails, made at the Philadelphia and Reading Rolling Mill in 1870, and then placed in the track, was removed in 1876, after having carried about 55,000,000 gross tons, and was on exhibition at the Centennial Exhibition. A piece of this worn rail, twisted cold, was also shown there. One of the same series of rails was allowed to remain in the track until 1878, and short sections of this rail, as well as one not worn, to show its original shape, are presented for your inspection. A comparison of the two will show that the top of the head or tread has worn down 3/16 ths of an inch during its nine years of service. It carried in that time 67,000,000 gross tons of freight, passengers, cars, and engines. This rail was made in the usual way of manufacturing iron rails at the Philadelphia and Reading Rolling Mill. The head was made from puddled iron bars, piled, heated, and rolled into bars, 4 1/2 and 3 inches wide by 1 inch thick, these bars, breaking joints, were made into a pile in section 9 inches square, heated and rolled into slabs 9 inches wide and 2 inches thick; the balance of the rail-pile was made of 4 1/2 and 3-inch bars, rolled from two-thirds old rails and one-third puddled iron, the

Jan 1, 1880

By Sydney H., Ball

ONE of the important mineral discoveries of the eighteenth century was , that of the Minas Geraes, Brazil; diamond fields. The production of this and of .other diamond discoveries in neighboring states made Brazil the premier producer of diamonds, succeeding India; its 140 years of supremacy finally passed to- South Africa- 60 years ago. Three times have diamonds contributed heavily to Portugal's somewhat checkered financial history; first in the sixteenth and seventeenth- centuries when the diamond trade of India was controlled by its citizens residing in ,Goa, later in the late eighteenth and the first 75 years of the nineteenth century when the Brazilian fields were the world's source of diamonds, and now, when the Angola diamond mines are the principal source of revenue of its colony, Portuguese West Africa. Certain phases in the history of the administration of the Brazilian field are sufficiently curious to warrant description.

Jan 1, 1929

By Charles Bell

THE Telluride mining district of southwestern Colorado is defined by the 37° 45' and 38° parallels of latitude and 107° 45' and 108° meridians of longitude. Telluride was never a boom camp, but has had a steady growth. In recent years, notwithstanding the business depression of 1920, the business has been the same as in normal years. The first prospector is said to have appeared in 1875, in which year locations on the Smuggler vein were made. Shipments were made in 1877 and 1878, and in 1879 milling the ores was attempted. While the district produced high-grade ores, it did not become important until 1890, when the Rio Grande Southern R. R. was completed from Ridgway to Telluride. The railroad has since been extended to Durango. In the fall of 1896, 400 stamps were in operation, and the annual production was $3,000,000.00, two-thirds of which was gold. The total production from 1875 to 1923 was: Gold $58,274,527; silver 41,830,920 oz., valued at $31,016,893; copper 15,258,866 lb., valued at $2,533,291; lead 166,056,484 lb., valued at $8,324,910; zinc 18,141,182 lb. valued at $1,323,787; or a total production of $101,473,408. All: claims are held in fee. Most of them are 1500 by 300 ft. but claims located within the last few years are 1500 by 600 ft. General supplies are obtained at Telluride, Denver, and Salt Lake. The largest mines are within 6 miles of the town of Telluride. Denver is 422 miles and Salt Lake is 439 miles, by rail, from Telluride. One-half of the distance to Denver and one-sixth of the distance from Telluride to Salt Lake is by narrow-gage railroad. The labor is efficient. The best miners are Italians and Austrians, then Slavs, Greeks, and Mexicans follow in the order mentioned. There are no labor unions. There are no serious mine pumping problems, the drainage being through adits. The Tomboy and Smuggler companies pump water from their reservoirs, the former for, milling and domestic purposes and the latter for milling, power, and domestic purposes.

Jan 2, 1924

By F.B. Foley, S.P. Howell

Not infrequently, in the case of the failure of a metal structure, such as a bridge, tank, airplane, gun carriage, etc., a doubt arises whether the failure was due, among other causes, to the effect of an overburden or of an explosive maliciously or accidentally exploded in contact with it. As few means of discriminating between the effects of these causes have been known and these means were of a rough qualitative character, it was surprising to find in the record of an inquiry into the failure of a structure, the statement that, by observations on the Neumann bands in the structure, it was possible to determine the speed of breakage in the metal and to distinguish between a fracture caused by an explosion and one caused by an ordinary mechanical strain. Such a criterion, if well proved, was of value to the explosives experts of the Bureau of Minea, the Ordnance Department of the United States Army and the Bureau of Ordnance of the United States Navy, but search showed no record of it in the literature nor did any of the metallurgists and metallographers consulted know of any data on which such a criterion could be based having been assembled and critically studied. However, it was universally held that there was promise in the idea and that there exkted unique facilities at the Bureau of Mines Experiment Station at Pittsburgh for the preparation, under definitely known conditions, of material for study by metallographers, and that material of value might also be obtained from the proving grounds of the Army and Navy. Therefore, with the approval of the Director of the Bureau of Minea and the Chiefs of Ordnance of the War and Navy Departments, the Chairman of the Division of Engineering of the National Research Council, on April 12, 1919, appointed a Committee on the Investigation of Neumann Bands, which has since been engaged in this study and which, after some slight change in its personnel, consists now of the following: Dr. William Campbell, Advisory Metallurgist, Bureau of Ordnance, Navy Department. P. B. Foley, Metallurgist, Bureau of Mines. S. P. Howell, Explosives Engineer, Bureau of Mines. Comdr. 0. M. Hustvedt, U. S. N., Bureau of Ordnance, Navy Department. Dr. Charles E. Munroe, Chief Explosives Chemist, Bureau of Mines.

Jan 1, 1923

By S. P. Howell, F. B. Foley

Not infrequently, in the case of the failure of a metal structure, such as a bridge, tank, airplane, gun carriage, etc., a doubt arises whether the failure was due, among other causes, to the effect of an overburden or of an explosive maliciously or accidentally exploded in contact with it. As few means of discriminating between the effects of these causes have been known and these means were of a rough qualitative character, it was surprising to find in the record of an inquiry into the failure of a structure, the statement that, by observations on the Neumann bands in the structure, it was possible to determine the speed of breakage in the metal and to distinguish between a fracture caused by an explosion and one caused by an ordinary mechanical strain. Such a criterion, if well proved, was of value to the explosives experts of the Bureau of Minea, the Ordnance Department of the United States Army and the Bureau of Ordnance of the United States Navy, but search showed no record of it in the literature nor did any of the metallurgists and metallographers consulted know of any data on which such a criterion could be based having been assembled and critically studied. However, it was universally held that there was promise in the idea and that there exkted unique facilities at the Bureau of Mines Experiment Station at Pittsburgh for the preparation, under definitely known conditions, of material for study by metallographers, and that material of value might also be obtained from the proving grounds of the Army and Navy. Therefore, with the approval of the Director of the Bureau of Minea and the Chiefs of Ordnance of the War and Navy Departments, the Chairman of the Division of Engineering of the National Research Council, on April 12, 1919, appointed a Committee on the Investigation of Neumann Bands, which has since been engaged in this study and which, after some slight change in its personnel, consists now of the following: Dr. William Campbell, Advisory Metallurgist, Bureau of Ordnance, Navy Department. P. B. Foley, Metallurgist, Bureau of Mines. S. P. Howell, Explosives Engineer, Bureau of Mines. Comdr. 0. M. Hustvedt, U. S. N., Bureau of Ordnance, Navy Department. Dr. Charles E. Munroe, Chief Explosives Chemist, Bureau of Mines.

Jan 1, 1923

By Paul L. Burkhart

THOUGH at an earlier period brief studies had been made by the Lehigh Navigation Coal Company Inc., it was not until 1924 that J. B. Warriner, then general manager, called for a comprehensive study of timber treatment, treating solutions, and related operations. Because of the impossibility of procuring accurate costs and other pertinent treating data, the American Wood Preserving Co. agreed to treat a car of mine timber at the Port Reading plant of the Reading Railroad. Fig. I shows the treating data collected at the treating plant on this timber, which was installed in two of the Lehigh mines in 1925. [ ] In the latter part of 1925, a survey of the tunnels and gangways of the company's Panther Valley mines was made to determine the proportion of gangways or tunnels timbered, cause of timber failures, approximate life of the average wood set and the approximate percentage of treated timber that it would be profitable for the company to use. Results of this survey appear in Table I. Because of the high percentage of timber that gave evidence of failure by rot, as noted in Table I, and a further study of the life of the sections where timbering was necessary, it was deemed advisable to fill 25 per cent of the yearly gangway timber requirement with treated timber. QUANTITIES AND TREATMENTS OF TREATED TIMBER PURCHASED In the early days of the program, none of the large treating companies would accept orders for small quantities of treated timber and the company was compelled to state the quantity of timber it would require at each operation in each month of the year. Table 2 is an example of the tabulation given to the various treating companies to assist them in making a yearly bid on the minimum quantity of timber required by the company during the year 1931. A bill of timber was calculated for each car, the weight of which would be between the minimum and maximum weight permitted for railroad-car loading. The treating company was paid for timber upon delivery at the operation specified. As extra cars of timber were required, they were ordered from the treating company, and payment was required on their receipt, on the basis of the piece or tonnage

Jan 1, 1942

By William Kelly

THE objeet of this paper is to describe the electric equipment at the iron-ore mines of Penn Iron Mining Co., Vulcan, Mich. and of Republic Iron Co., Republic, Mich.; to give the result's of tests; and to discuss the methods in use from an operating as well as from an efficiency standpoint. Electricity was introduced at the Penn mines for pumping, hoisting, and compressing air in the spring of 1907, upon the completion of a hydro-electric plant built by that company on the Menominee river about 4 miles from the mines. This plant was described in a paper1 presented before the Lake Superior Mining Institute. A paper2 presented at a meeting of the same Institute describes some of the operating features, and the safety devices of the electric hoist at the Curry shaft were briefly described in the Proceedings of the First Co-operative Safety Congress held under the auspices of the Association of Iron and Steel Electrical Engineers at Milwaukee, Wis., Sept. 30 to Oct. 5, 1912.

Jan 2, 1914

By Frederik W. de Klerk

INTRODUCTION During the past 40 years, there has been in the United States of America and other industrialised Western countries a distinct displacement in the procurement of minerals from domestic sources towards an increased dependence on imported minerals. This was caused in part by one or each of the following: a lack of local supply of particular minerals, domestic source depletion or exhaustion and the relative ease and inexpensiveness of obtaining minerals from comparatively unexploited sources in underdeveloped and some developing countries, notably in the Middle East, South America, Southern Africa, and Australasia. Governments of the industrialised nations, concerned about the reliance of their economies on imported raw minerals examined both the degree of reliability and the extent of mineral resources in the countries and regions supplying the essential minerals. This brought a painful awareness of the vulnerability of industrialised countries as a result of the possible interruption of their mineral imports. In this regard, the United States of America may be quoted as a case in point: a report by a House of Representatives Subcommittee on Mines and Mining (Santini Subcommittee)1 revealed that the United States in 1980 was dependent on foreign sources for more than 50 per cent for 24 of the 32 minerals essential for national survival. The Subcommittee also acknowledged that although the United States may develop its own alternative energy sources, there are in many cases no substitutes for the strategic + minerals imported from foreign sources, from countries which are often unstable at best, hostile at worst. This resulted in various policy responses as well as contingency measures, amongst other, renewed emphasis on the utilisation of domestic mineral resources, an intensified search for substitutes of critical minerals and increased stockpiling programmes. Increased attention was devoted to analyses of the political and economic conditions prevailing in the regions from which strategic and other minerals are exported to the industrialised countries, and the formulation of policy measures vis-a-vis those regions. One region which attracted a considerable degree of attention has been Southern Africa, and in particular South Africa.2 The Santini Subcommittee affirmed that while the bulk of the minerals imported by the United States is supplied by a number of source countries, a host of critical[t] minerals vital to the well-being of that country (and this includes all the Western industrialised countries) originates from Southern Africa, a region, deservedly referred to as the "Persian Gulf of Minerals". Apart from the Republic of South Africa the mineral-rich countries concerned are Angola (diamonds, iron ore, oil), Botswana (diamonds, coal), South West Africa/Namibia (diamonds, uranium), Zambia (copper, cobalt), Zaire (industrial diamonds, copper, cobalt) and Zimbabwe (gold, nickel, chromium, asbestos). The Subcommittee however noted that, with the exception of cobalt, the greatest portion of the reserves of the critical minerals listed, lies within the borders of South Africa. SOUTH AFRICA A RELIABLE PURVEYOR OF MINERALS In view of the continual instability and political risk, along with the nationalisation of mineral industries in third world countries, importing industrialised nations have in recent years become more and more concerned about security of long-term supply, and have in consequence begun to diversify their mineral enquiries to areas where the following conditions prevail: • Long-standing record of consistency of supply; • An economic system of private enterprise; • Political stability; • A well integrated infrastructure, with a maintenance of transportation and development costs at realistic levels, and • Attractive investment opportunities, with security of the return of profits.

Jan 1, 1982

By John L. Schroder

The demands for increased productivity on the 1967 coal industry have generated new operating trends and fresh approaches to old methods, which have enabled the industry to keep pace with the expanding economy. Changes, while not radical in concept or design, have been plentiful and are marked by the refinement of the already tried, tested and proven. Perhaps not since World War II have there been demands on equipment manufacturers to design and deliver such diversified types of machines as those required by the industry in the past year. Equipment developments-following a plan which calls for higher productivity, lower maintenance costs and greater machine availability- have tended more toward increased horsepower and heavier, more rugged equipment. Electrical and mechanical components, designed in many instances with maximum reliability rather than initial costs as the main criterion, have contributed to the improvements in over-all performance. High-strength, specialty steels are finding use in a wide range of equipment applications. The horsepower capacity of electric motors being installed is more frequently being rated on a continuous basis rather than the former one hr or less and, as a result, fewer failures now occur because of overloading. These developments reflect the pyramiding cost of equipment down-time and represent definitive progress in reducing the magnitude of the problem.

Jan 2, 1968

By Joseph L. Patrick

Geologic exploration, which has experienced an upward trend in the United States since 1962, continued with increasing activity through 1965. New, spectacular discoveries of recent years and continued questionable economic and political climates in many areas of the world have continued to focus the exploration attention of an increasing number of companies on the United States. Traditional geologic field methods are being bolstered by development of new methods, techniques and geophysical instruments. Reports from the states emphasize that successful exploration is dependent upon the combined effort of geochemistry, geophysics and geology, with high quality laboratory support of the field effort becoming increasingly necessary. PROGRAMS NOW UNDERWAY IN WEST During 1965 mineral exploration reached an all- time high in Nevada. Although examinations are being carried on throughout the State, much of the work is limited to two areas. The first area to attract recent exploration interest, initiated by discovery of the Carlin gold mine by Newmont Mining Corp., is an area of windows near the leading edge of the Roberts Mountains thrust fault in northeastern Nevada. Included in this area are the old camps of Mountain City, Battle Mountain, Cortez, Mineral Hill and Eureka. Major mining companies are using a combination of surface mapping, geochemistry, geophysics (largely induced potential surveys), following up with drilling. The second area of exploration is along the Walker Lane, a wide shear zone that parallels the Nevada-California boundary from Virginia City to Las Vegas. Activity has been intense in the Tonopah-Yerington area. Discovery of a large copper-iron deposit following an airborne magnetometer survey first focused recent attention on Walker Lane. Sixteen major companies are involved in exploration in the State.

Jan 2, 1966