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By J. Price Wetherill

THE coal-seams that are worked vary from 32 to 100 feet in thickness, and occur at all angles of inclination, but are never flat for any great extent. They contain coal, slate, and an unsolidified coal, called dirt by the miners, in various proportions, a uniform seam of coal alone being rare. The upper walls are composed of conglomerate, sandstone, or slate; the first two hard and solid in texture, and withstanding the action of the atmosphere and moisture sufficiently well to offer but little trouble to the mining operations ; while the latter crumbles rapidly, owing, in part, to the decomposition of iron pyrites which it contains in large quantities, and in part to its own friable character, and requires constant care to avoid accidents to the men working below it, and to prevent its mixing with the coal mined. The floors are composed of slate. As in all mining operations, the. general system pursued is to reach with a permanent outlet such a point in the seam as will

Jan 1, 1877

By Monte J. Pool, Rudolph Speiser, George R. St. Pierre, William T. Ebihara

Standard free energies of formation of WO,, W O W20058 and WO3from oxygen and the lower oxide or tungsten have been determined in the tempel-ature range of 700° to 1220°C. A tentative W-O phase diagmm is presented based on the evidence that the oxide phases, "W18O49" and "W20058", are unstable at l~atm total pressure, below 585° and 485°C:, respectively. A HE need for a complete quantitative treatment of the phase equilibria of the W-O system has been establishedby metallurgists during the past few years. In an attempt to improve the endurance of tungsten exposed to oxidizing atmospheres at high temperatures, many research groups have studied the kinetics of tungsten oxidation. The reverse process, the reduction of the tungsten oxides to metal, has also been investigated to some extent. Regardless of the particular interest, metal to oxide or oxide to metal, a knowledge of the phase equilibria of the W-O system is required to properly interpret all of the kinetic observations. It should be possible to state the stable phases of the W-O system at any given values of the chemical potential of oxygen and the temperature.

Jan 1, 1962

By Peter L. Raffo, Walter R. Witzke

RHENIUM has a melting point of 5750°F, the second highest value among the metals.1 Its refractory nature should thus make it a useful material at high temperatures. The only available data on the high-temperature properties of bulk rhenium are from the work of Flagella and Tarr.2 These authors have shown that, over a wide range of temperatures and stresses, no appreciable linearity exists in a log-log plot of the minimum creep rate or rupture life vs stress. The purpose of the present letter is to describe some exploratory experiments designed to study the creep rate-stress-temperature relation and other facets of the creep of rhenium. The tests were carried out in vacuum in the temperature range 2200" to 4000°F (0.43 to 0.72 Tm,) at stresses ranging from 4 to 20 ksi. The powder metallurgy rhenium was purchased as 0.04-in.-thick sheet. The sheet is nominally 99.97 pct pure with the major impurities being iron (70 ppm) and molybdenum (25 ppm). The sheet was machined into specimens having a 1-in. gage length and a 0.25-in. gage width. The specimens were preannealed in hydrogen at 3000°F for 1 hr. This treatment produced

Jan 1, 1970

By Ralph Hultgren

A CONSIDERABLE interest in the subject of superlattices has been mani-fested by many papers and reviews that have recently appeared, both in physical and metallurgical publications. This interest is due largely to the apparent simplicity of the ordering process, which permits the explana-tion of many phenomena on the basis of elementary theory. Moreover, ordering may cause important changes in the physical properties of alloys. In this paper, we shall discuss the causes of superlattices in terms of simple properties of the elements that give rise to them, together with a series of experiments performed to test our conclusions. Evidence is presented that in some cases the process of ordering is more complex than might be supposed. While the different species of atoms are usually found in random posi-tions in alloy lattices, in some cases unlike atoms tend to be nearest neighbors. Bethe'st "order of neighbors" is a statistical measure of this tendency. At suitable compositions it is possible for atoms in large regions to be regularly arranged, which causes superlattice lines to appear in X-ray diffraction patterns. Bragg and Williams2 have dealt with this "long-distance order" in their fundamental work on superlattices. Excellent discussions of superlattices are to be found in current reviews.3,4

Jan 1, 1939

By D. R. Semmes

The possible oil territory of Alabama can be readily divided into two regions, the Paleozoic area of the north, and the Coastal Plain province of Cretaceous and younger formations lying to the south. This latter area has received much attention in the last few years and has been described by a number of writers.' Although the possibilities of the Cretaceous series have been much emphasized by recent writers, the fact remains that the two, or possibly three, localities where oil or gas have been found in anything like paying quantities are confined to the area of Carboniferous rocks. Moreover, almost all of the oil seeps and a good percentage of the gas seeps are confined to this area.2 Topographically, as well as structurally, the Paleozoic area can be divided into three rather well defined provinces: (1) The broad, open Coosa Valley lying adjacent to the crystalline oldland, with comparatively little relief, except for occasional longitudinal ridges and rather intense folding; (2) the plateau region of horizontal or gently warped Pennsylvanian strata broken by occasional anticlinal valleys aligned northeast and southwest, outliers of the Coosa Valley proper, in which the older Paleozoic formations are exposed—a region of much relief (200

Jan 1, 1921

By John E. Sherborne, William M. Newton

THE relation between the properties of electric logs and the fluid used in drilling a well is briefly discussed in this paper, and the fact that the resistivity of the drilling mud and its filtrate can appreciably affect such logs is shown. Apparatus was designed and a procedure established to determine the effect of various factors on the resistivity of drilling mud. Five muds commonly employed in California were tested and the following observations were made: I. The effect of raising the temperature from 80°F. to 180°F. is to decrease the resistivity of the mud or filtrate approximately 50 per cent. 2. The resistivity of the mud in most cases closely approximates that of its filtrate. 3. The change in the resistivities of muds caused by the addition of chemical is not the same function of the amount of chemical added for each mud. 4. The effect produced by increased sodium chloride content is to reduce markedly the resistivity of the mud and its filtrate. 5. Weighting materials, such as Baroid and limestone, tend to increase the resistivity of drilling mud. 6. Cement and counteracting reagents reduce mud resistivity.

Jan 1, 1942

By C. Chiou, M. E. Fine

While Gunier-Preston zones are growing in Al-4.2 pct Cu at room temperature, Young's modulus, measured dynamically, increases about 0.4 pct. From the change in modulus with time the exponent of time in the rate equation for growth of the zones was deduced to be %. From a comparison of the rates of increase of modulus at 1, 28, and 42°C an activation energy of 12 to 14 Kcal per mole is computed. These findings support the idea that copper atoms are supplied along dislocation channels to growing zones. In alloys the elastic constants will be functions of the distributions of the atoms. If the degree of ordering or clustering is changed, one expects a corresponding change in the elastic constants. During age-hardening of aluminum-copper alloys at room temperature, the copper atoms cluster on 100-type planes in the aluminum lattice forming

Jan 1, 1959

By C. C. Griggs

FROM its inception, a limestone quarry or mine should be under the direction of a capable engineer. Before it becomes a reality, he should outline the future results, plan the most economical methods for moving the materials and the most efficient equipment, and pilot the undertaking along the narrow pathway of success, avoiding the pitfalls of uneconomical production and the precipitous walls of scanty profits. Inspection of successful limestone properties shows that all have had difficult engineering problems, the solution of which have required keen engineering ability. In approaching a subject of this nature, it is logical to follow the progress of the limestone operation from its inception to the end, as reflecting the engineering required. There are four major divisions: Investigation, equipment, development, and operation.

Jan 2, 1925

WALTER N. CRAFTS,* Toronto, Canada (written discussion?).-During the forging of 9.2-in. shells -for the United States Army, it was noticed that better results were obtained in certain instances when test bars had been held sometime before pulling. An investigation, therefore, was made by our metallographer, Mr. F. M. Arnold, to determine the effect of seasoning. The forging consists of a single operation, piercing a solid cast blank. The test sections were cut from the walls by an oxyacetylene flame, one piece from the nose end and one from the base on the opposite side. The test pieces were not heat treated in any way and the tests and seasonings were carried on at normal atmospheric temperatures. The specifica-tions were as follows: Standard 2-in. test bar, 0.505 in. in diameter; elastic limit, over 19 long tons, or 42,500 lb.; ultimate stress, 39.6 to 49.1 long tons, or 87,500 to 110,000 lb. per sq. in.; elongation, over 13 per cent. As a preliminary test two heats were selected; BP555, which was tested and reported failed on elongation on Aug. 20; and B01771, which was tested and reported failed on Aug. 24. On Aug. 29, retests were cut and machined from the same shells and held till Sept. 3 (5 days) when they were pulled. Both sets of results are given below.

Jan 12, 1919

By J. R. Thoenen

THE preper classification of mining methods has received the earnest study of many mining engineers and has resulted in much technical controversy, depending no doubt upon the point from which classification is viewed or the use to which it is put. So far as the writer is aware, the discussion has invariably centered around the classification of underground mining methods, and only superficial attention has been directed to surface methods. Volume 72, page 10, of the Institute Transactions, presents such a classification, sponsored by the Mining Methods Committee of the Institute. A similar classification by Prof. Hugh P. Nicholson appeared in Mining and Metallurgy in October, 1934. The two classifications are quite different in their treatment of underground methods but are identical in classifying surface methods, although Professor Nicholson does suggest possible further divisions for surface mining and admits that such subdivision is more difficult than appears at first. Surface subdivisions as given by these two authorities are as follows, showing that in spite of rearrangement the two classifications are identical: From his experience of many years in the study and operation of both underground and surface metal and nonmetallic mines, the writer does

Jan 1, 1942

By J. R. Thoenen

THE preper classification of mining methods has received the earnest study of many mining engineers and has resulted in much technical controversy, depending no doubt upon the point from which classification is viewed or the use to which it is put. So far as the writer is aware, the discussion has invariably centered around the classification of underground mining methods, and only superficial attention has been directed to surface methods. Volume 72, page 10, of the Institute Transactions, presents such a classification, sponsored by the Mining Methods Committee of the Institute. A similar classification by Prof. Hugh P. Nicholson appeared in Mining and Metallurgy in October, 1934. The two classifications are quite different in their treatment of underground methods but are identical in classifying surface methods, although Professor Nicholson does suggest possible further divisions for surface mining and admits that such subdivision is more difficult than appears at first. Surface subdivisions as given by these two authorities are as follows, showing that in spite of rearrangement the two classifications are identical: From his experience of many years in the study and operation of both underground and surface metal and nonmetallic mines, the writer does

Jan 1, 1942

By George Moore

IN spite of many investigations of the occlusion of hydrogen in iron, the nature of the process and the reasons for the accompanying effects upon the metal are still open questions. This is in large part due to three causes: (1) the difficulty of obtaining iron of adequate purity as starting material; (2) the occurrence of allotropic transformations, which compli-cate the effects; and (3) the fact that the body-centered cubic modifica-tion does not lend itself readily to crystallographic investigation. The present paper attempts a critical review and correlation of the somewhat scattered and disconnected existing observations, and an experimental determination of the extent to which the conclusions that appear to follow from these are applicable to iron of really high purity, studied under well-defined conditions.

Jan 1, 1939

Mr. Brown : .That part of the Standard Company's plant which has been added since the publication of Mr. Leggett's paper, and is described in mine, renders the single-phase, alternating system, which Mr. Hale has called " unelastic," much more elastic than it had been. The original plant at Bodie was substantially the same as the Telluride plant mentioned in his paper. The machines came from the same shops, and were practically the same; but while the Telluride Company has changed completely to a polyphase system, the Standard Company has retained its original plant, but has belted on a directcurrent generator at the receiving end, thereby converting the water-power into electricity, electricity into power, the power into electricity, and finally again electricity into power for use in the mines. This is a roundabout course, to be sure, but it shows that there are possibilities even in the out-of-date single-phase system. The only point perhaps, that deserves particular notice with respect to the hoist is the fact that the rheostat, or starting-resistance, was not built originally

Jan 1, 1897

By George F. Weaton

Mining differs from the ordinary industry in that most industries and enterprises have an indeterminate life, apparently perpetual, and therefore, are not called on to replace the original investment. In mining, however, when the ore bodies are mined out, there is nothing left, The original capital investment must, therefore, be returned to the investor by the time that the profitable life of the mine is ended. When the operating company makes no provisions for perpetuating its life by investing a portion of its earnings in other properties, the usual procedure is to pay the investor, periodically, a dividend sufficiently larger than the risk return on his investment to enable him, if he reinvests this overplus at a safe rate of compound interest, to replace his original capital by the time the mine is exhausted. This overplus constitutes a return of invested capital. In estimating the value of a mining enterprise, the work leading to the final result may be divided into two parts. The first is the examination of the property to determine ore reserves, mining costs and profits, financial requirements and future prospects. Whatever conclusions are reached in this phase of the work depend on the experience, thoroughness and integrity of the examining engineers. The second is the calculations pursuant to the field examination.

Jan 5, 1973

By J. A. Berge, R. S. Mateer, R. G. Aspden

IN a study of the cold-rolling characteristics of iron-base alloys with 3 to 12 pct Al, the influence of aluminum content on the cold-rolling textures was evaluated. This work was undertaken to determine if binary iron-aluminum alloys possessed cold-rolling textures similar to other body-centered-cubic alloys and to contribute additional information on the effect of solute concentration on the cold- rolling textures. Gradual changes in cold-rolling textures with an increase in solute content have been observed in copper1 and in titanium.2 Iron-base alloys containing 3.0, '6.0, and 12.0 pct aluminum were vacuum-induction-melted in a magnesia crucible and permanent-mold cast. The materials used were high-purity electrolytic iron and 99.99 pct grade aluminum. Each ingot was 1 in. square in cross section by 12 in. in height. The bottom half of each ingot was soaked for 1 hr at 1000°C and rolled at 1000°C to a thickness of 0.055 in. with the long axis of the ingot parallel to the rolling direction. The strip was reheated between passes to maintain a rolling temperature of 1000°C.

Jan 1, 1960

By Charles Mitke

EXCLUDING top-slicing, and sublevel caving, large production caving methods may be divided into two general classes, the branch raise, or undercut caving method, and the combined shrinkage and caving method, each of which has a number of variations, the result of continual efforts towards obtaining lower costs and better extraction, by the introduction and substitution of minor improvements and modifications. EARLY CAVING METHODS Present caving methods are the cumulative result of developments covering a period of many years, with the most rapid growth during the past 15 years. They originated, presumably, from early English stoping methods, and, as far as is generally known, were first introduced in the Michigan iron district. They have had their greatest expansion and application in the large low-grade porphyry coppers. In their present form, they are probably a development and combination of sublevel caving and shrinkage (back-stoping on ore) with gravity handling of broken material. Sublevel caving, as practiced in the Michigan district today, is a combination of drift, or crosscut, mining, with top-slicing, and caving, supplemented by later refinements in the shape of mechanized handling of broken ore. A height of anywhere from 16 to 20 ft. is generally taken, and the ore is drilled and blasted along the drift or crosscut for half this height (say 8 to 10 ft.), after which the upper 8 to 10 ft. caves and breaks of its own weight, with comparatively little assistance from drilling. This

Jan 1, 1928

By H. W. Kropholler, L. A. Cramer, E. T. Woodburn, J. C. A. Greene

A generalized mathematical structure is proposed whereby internal species mass flows within a flotation network are defined uniquely by a matrix of enhancement factors. An element of the enhancement factor matrix is defined as the ratio of the mass flow of that species leaving a given cell in the concentrate to the species mass flow leaving the same cell in the tailings. To predict the enhancement factors, knowledge of flotation kinetics effects is required. Recently experimental data has become available relating to the performance of industrial flotation circuits which indicate that the discrete or discrete-distributed kinetic schemes are capable of reasonably effective simulations. These simulations show the importance of including froth effects. The prediction of performance of networks from small-scale batch tests on flotation streams shows that the model for the froth phase used in the simulations does not scale-up well and that aeration effects are also difficult to predict. The network analysis should be useful in differential flotation of complex ores and it is disappointing-in this context that little information on the kinetics of activation and depression is available.

Jan 1, 1976

By R. J. Armstrong, J. J. McKay

The Montana Phosphate Products Co. is currently operating three underground phosphate mines in Powell County, MOnt. † In this area the Phosphoria formation is from 35 to 50 ft thick and contains a bed of phosphate rock varying in thickness from 2 1/2 to 5 ft, overlain by 12 to 30 ft of cherty quartzite, and underlain by about the same thickness of quartzite and shaly to cherty beds. In general, the phosphate bed has a reasonably hard quartzite footwall, as well as a hard cherty hanging wall, both of which greatly facilitate the mining operation. Folding has deformed the phosphate bed to a considerable degree in the area. It is carried to surface by several of the anticlines and lowered to considerable depths in some of the syn-clines. The main structural features affecting the mining operations of the company are the Garrison anticline and the adjoining syncline and succeeding limb of a second anticline on the east (Fig I). The axis of the folding strikes roughly northwest-southeast. The three mines, namely, the Anderson, Graveley, and Luke are on different limbs of the above folds. Accordingly, the dip of the bed, and consequently the mining method, in each mine differs to a considerable degree from that of the others. For this reason, each operation will be dealt with separately. Anderson Mine LOCATION AND DEVELOPMENT Topographically this mine is in a narrow valley, the bottom of which has an altitude of 5200 ft. The phosphate bed outcrops near the ridge on the east and dips towards the valley floor at an angle of from 25 to 30°,

Jan 1, 1950

By C. A. O’Connell

Surface exploration drilling at Mufulira started in 1928, with drillhole No. 1 intersecting ore near the eastern fringe of the deposit. Subsequent drilling along strike intersected ore until the western fringe was fixed some 7500 ft west of drillhole No. 1. Further intensive drilling down dip disclosed a large triangle of ore with its apex 3350 ft deep. It contained approximately 11 6 million tons of ore at 4.41% total copper in three superimposed orebodies. The east and west limits of the orebodies were presumed to have a pronounced rake to the north with a strike length of 8000 ft. Subsequent exploration underground seemed to bear out this presumption to the 1150 ft level. In 1947, attention was directed to the area west of the known orebodies in conjunction with plans for increased production and increased depth of the mine workings.

Jan 12, 1962

By F. W. Luerssen, J. F. Elliott

F LUSHING the early slag from a stationary open Fhearth having a high percentage of hot metal in its charge is necessary in order to remove silica from the system. The flush slag is strongly oxidizing and is somewhat acidic. It has, however, considerable capacity to extract phosphorus from the bath and it also removes considerable manganese. It seems probable that factors which control the distribution of phosphorus and manganese between slag and metal in the refining period also should be dominant in the flush and postflush periods. Several studies, as summarized elsewhere,1,2 support the viewpoint that conditions closely approaching equilibrium for these elements are rather readily established during the refining period. Over the years these studies have repeatedly demonstrated that 1—high slag v01ume, 2—low bath and slag temperature, 3—basic slag, and 4—strongly oxidizing slag favor rapid elimination of phosphorus from the bath to the slag. They also show that the following conditions favor retention of manganese in the bath: 1—low slag volume, 2—high bath and slag temperature, 3— basic slag, and 4—minimum oxidizing power of slag. When it is considered that the flush slag often carries as high as 75 pct of the manganese charged and only 25 to 60 pct of the phosphorus charged, it is evident that in removing silica much manganese is sacrificed but phosphorus removal is far from conplete. Because of overriding circumstances, this is accepted in most operations and actually it is considered to be inevitable. This may account for the fact that little attention has been paid to conditions affecting the elimination of phosphorus and manganese in the flush slag. A recent study of the behavior of various charge oxides has developed considerable information on the flush and postflush periods. Because the data are felt to be of general interest, they have been brought together and Presented in this paper. The object is to show the various factors in the flush and postflush periods which influence elimination of phosphorus and manganese. Physical Conditions During and After Flushing Physical conditions existing during the flush vary from plant to plant, from shop to shop, from furnace to furnace, and even from heat to heat. They are strongly influenced by the physical and chemical character of the charge oxide which is ordinarily necessary to provide sufficient oxidizing power early in the heat. Invariably the period is characterized by a vigorous reaction between the principal re-actants: the hot metal being added and the charge oxide. During the flush, it is probable that the slag acts to some extent as an oxidizer; but, because of the critical influence of the behavior of the charge oxid'e on flushing action, it seems apparent that the oxide itself is the dominant oxidizer. Fig. 1 shows the course of two heats which were selected as being typical of the group studied. Heat A was charged with 55 pet hot metal, based on the total metallics charged, and heat B had 57 pct hot metal. As indicated in Table I and Fig. 1, the melt-down slag, which is not usually voluminous and which is principally FeO, expands greatly in volume and will show rather high levels of SiO2, MnO, and P2O5 very soon after the beginning of the hot metal addition. Simultaneously, large volumes of CO are liberated which cause violent mixing of slag and metal. It is of interest to note that the time required to bring carbon down to a low level is very much longer than that required for the removal of silicon, manganese, or phosphorus. At the end of flush, carbon in the bath is still approximately 2 pct. When strongly reducing hot metal is brought into contact with strongly oxidizing conditions within the furnace! it is probable that the rate of mass transfer to the slag (and atmosphere) of silicon, manganese, phosphorus, and carbon initially depends principally on the rates at which the two participating phases are brought into contact That is, it depends on the nature of the various reactions. Later in the flush period, when the scrap is virtually all dissolved and the action of the bath has settled down to a steady and somewhat gentle boil, it is likely that other factors, such as the transfer of oxygen across the slag-metal interface, become dominant. The temperature of the slag-metal system is far from uniform. Heat is being driven by the flame down through the slag. Bubbling and surging of the metal also frequently brings portions of the bath in contact with the flame. At areas of contact between the ore and liquid metal, or slag and liquid metal, the oxidizing reactions generate much heat. On the other hand, scrap is being melted which tends to absorb large quantities of heat. Because the liquid bath is high in carbon, the steel scrap is brought into solution rapidly. This can proceed at a rather low temperature; and until much of the scrap has been taken into solution, the bath temperature would not be expected to increase appreciably. Consideration of these factors leads to the conclusion that during the flush period the slag should be rather hot and the bath relatively cold. Both observation and temperature measurements bear this out. Experimental Data The extended program of charge oxide evaluation permitted study of the widely varying conditions existing during the flushing period. Slag and metal analyses and bath temperatures reported herein (Tables I and 11) were obtained toward the latter portion of the work. Four different types of charge oxide, sinter, two types of hydraulic cement-bonded soft ores, and a pyrobonded agglomerate were used in the study. Although the heats reported were from only one 205 ton furnace, they show variations in flush slag analyses all the way from 25 pct FeO, which is typical with the use of a hard natural charge ore, to 45 pct FeO which resulted when a very poorly agglomerated fine ore was used. The physical behavior of the flushes showed a correspondingly wide variation from well controlled reactions to violent surges following periods of inac-

Jan 1, 1956