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By Charles A. Ashburner

VERY little is known of the economical value of the coal-betas of. the State of Texas. The first authentic statement in regard to their occurrence is that contained in the reports of the United States Explorations for the Pacific Railroad, near the 32d parallel of latitude, published in 1853-55. Professor William P. Blake reports, "that a number of seams of bituminous coal, varying, in thickness from two to four feet, have been opened along the Brazos River, in Young County, about one hundred and fifty miles west of Fort North." Dr: Shumard also states, "that the characteristic fossil forms of the Carboniferous Era have been found with this coal, and considers the ago of the formation established. Fossils obtained from the carboniferous limestone remove all doubt of the age of these deposits."† In the spring of 1879, I was called upon by. some Eastern capitalists to make an examination of the Brazos coal-field, in order to obtain the thickness, extent, and value of the coal which could be mined and be- made merchantable for steam, heating, and metallurgical purposes. The demand for coal in this section of the country is great, and a fuel. which in our Eastern markets might be considered of inferior quality, would here find a ready sale. It must be remembered that the market value of a coal does not depend upon its absolute purity, but upon its actual value in heat units which it is capable of producing. A poor coal which can be cheaply mined near the: consumer, is infinitely more remunerative to a mining company than a superior coal whose cost to the consumer is greatly increased by high mining charges and railroad freights. The value of the Texan coals does not depend upon their purity but upon their low first cost and nearness to a market. A glance at a geological map of the United States, will show that the Brazos coal-field is the extreme southwestern extension of what may be called the Missourian, Fourth or Western, bituminous coal * I am permitted by the gentlemen for whom the examination was made to publish the general statements contained in this paper. † Macfarlane's Coal Regions of America. More recently brief mention has been made of the coal-field in the pamphlets of the State geological survey. These reports are, however, too general, too indefinite, and too impracticable to permit of any conclusions as to the value of the coal as an economical, merchantable fuel.

Jan 1, 1881

By George Stanley Scott

Many requests for information as to the possibility of washing coals to some predetermined percentage of ash or sulfur have suggested that the producers aim to satisfy some degree of purity set by the user of the fuel, rather than to attain the greatest economic benefit to all concerned. This paper is written to show that the highest economic purity of washed coal can be determined from washability studies of the raw coal, costs of mining and washing coal, and data on the effect of ash and sulfur on the value of the coal for the particular use for which it is intended. Coke fob Blast-fuenace Use For purposes of illustration, we take the case of coal washed for coke to be used in the iron blast furnace. The method outlined can be made general in its application by substituting for the figures used here the actual operating figures for the particular case under consideration. In general, it costs the blast-furnace operation from 8 to 25 c. per ton of pig iron to slag out each 1 per cent. of ash introduced into the blast furnace by the coke. This figure depends on which one per cent. of ash is removed, and decreases with decrease in ash. When blast furnaces and coal mines are considered as a whole, the figure decreases to zero and then becomes negative, on account of low recovery of washed coal. Various figures1 have been given by different investigators. These figures necessarily differ, not only on account of the differences in operating costs but on account of the difference in the respective fuels as well. For the purpose of this paper, which, as explained, is to point out a method of attacking a certain problem, the figures used in the exposition of the method are of secondary importance. It is apparent that no universally applicable figures can be used, because there are none. Each plant has its own coal,2 its own operating cost, and its own conditions.

Jan 1, 1930

By Patrick M. Hurley

The relationships between mineral deposits and various plate margin mechanisms are examined under the constraints of radiogenic isotopes and other geochemical indicators. It seems like1 y that: (1) deposits of the spreading ridge association are fairly ubiquitious through most of geologic history and can be recognized by the lithologic assemblage and primitive lead isotope ratios; (2) most metals in the island arc association are not derived entirely from a subducting oceanic plate, and have a partly continental affinity; (3) subduction beneath a continental plate generates ores which are derived either from the downgoing plate or from the lower crust; (4) the heating of a continental plate by thickening or by mantle plumes may develop a metallogenic province involving extraction of metals from the curst; (5) rifts and grabens developing thick sections of marine sediments with evaporites may be the locus of base metal mineralization by movement of reducing brine solutions resulting from diagenesis and bacterial reduction of sulfates

Jan 1, 1978

By B. Das, V. Hucka

In light of the present energy crisis, coal appears now as the only reliable source of energy. The production of coal is expected to regain a rising trend after the latest slump. Aside from the competitive price with natural gas and oil, the other retarder of coal production is its environmental pollution effect. Gasification of coal has been advanced as the partial solution to the energy-ecology crisis. All the Advantages In situ gasification of coal may be considered a further step in this direction. It carries all the advantages of normal coal gasification as a stable source of energy; it is clean to handle and nonpolluting of the environment. It partially and sometimes fully does away with mining, makes uneconomical low grade coal and lignites economical and places some formerly unworkable seams within the scope of modern technology. The seams posing problems for mining due to tectonic disturbances may be converted into gas in situ. Low grade coals, such as lignites, which otherwise would be left in nature as uneconomic wealth, may be exploited by underground or in situ gasification. Thus, in situ gasification is likely to increase the exploitable reserves of coal and may reduce the cost of production. An additional merit of this method is that coal substance never reaches the surface and there is no problem of cinder disposal.

Jan 8, 1973

By C. V. Millikan

When a flowing oil well is being drilled in with cable tools, it is difficult to determine when an additional streak of pay sand is drilled. By placing a gas meter on the gas-release line from the oil and gas separator, any increase in volume of gas that comes with oil production is recorded. In addition to the better knowledge of sand conditions, these data are a valuable aid in determining the size and depth of shots, plugging off water, and estimating ultimate production. The meter also gives a record of operation while the well is drilling in; and if allowed to remain on the well after completion will give information that may lead to a more efficient recovery of the oil from the sand. A VERTICAL cross section of any oil sand will show great variation in porosity and oil content. In some sands, the entire thickness contains oil, the variation being only the degree of porosity or oil content, but more often the pay streaks are distinctly separated by shells or barren streaks. These pay strata vary in number and may be thin or thick. The total thickness of the sand may be several tens of feet while the part containing oil may be only 1 or 2 ft. thick. The amount of production is not proportional to the thickness of the sand but rather the thickness of the pay streaks. If the total thickness of the sand or the amount that can be drilled is small, or if the initial production is small, the depth at which each stratum of pay is encountered can be determined sufficiently accurately for all present economic purposes. However, when drilling through sand of considerable thickness, giving large initial production, especially where conditions necessitate that the production go through the same gas trap with that from one or more wells already producing, it is difficult to determine the depth at which the pay strata are encountered even accurately enough to guide the placing of shots, and small pay streaks are apt not to be recognized at all.

Jan 9, 1925

By S. Ramachandran, R. A. Walsh, J. C. Fulton

A method has been developed for calculating the oxygen content of commercially melted stainless steels. Application of thermodynamics to the de-oxidation reaction in straight chromium and Cr-Ni stainless steels has resulted in a set of equations DURING the past 30 years, many rewarding developments have resulted from the application of physical chemistry to steelmaking. A need still ex- which permits the calculation of oxygen contents. The model was programmed for computer calc~ilations. The validity of the method was demonstrated on routine oxygen samples from numerous commercially melted heats of stainless steel. ists for further progress in the use of thermodynamics to meet the more stringent requirements for cleaner steel. Current electric furnace practices have been developed around minimizing residual-oxygen content, one of the most important factors controlling the inclusion content of stainless steels. The residual oxygen is controlled by the use of deoxidizers during the finishing period and a number of empirical rules have been evolved. Although this feature of electric furnace practice has long been in use, only in recent years has funda-

Jan 1, 1963

By Raymond S. Weimer

OF the several characteristics of a coal that influence its suitability for use in a given piece of burning equipment, the clinkering and slagging characteristics of the ash of the coal are highly important. They determine the maximum rate at which the coal may be burned on a stoker or in pulverized form without difficulty from damage to metal parts, from erosion of refractory walls, or from stoppage of gas passages by accumulation on the tubes. They also determine the minimum rate at which a slag-tap furnace may be operated without difficulty in removal of the ash in fluid form. NEED FOR A BETTER CRITERION In common with other producers and users of coal, the Northern Illinois Coal Corporation has long used the available methods for the measurement of the clinkering characteristics of coal ash, chemical composition and fusion temperature of the ash, as criteria for the selection of coal that would suit the particular requirements of its customers. These two available criteria have greatly helped in the problem of selection but it is unnecessary to dwell upon the fact that they are not completely adequate for the purpose. The composition of the ash and its clinkering tendency vary widely over the company's mining area. In a certain period, some years ago, an unusual amount of severe clinkering of the ash of coal shipped made extremely acute the need for a better criterion of the clinkering that might be expected. It was also desirable that the criterion result from a reasonably rapid method, so that the clinkering characteristics of the coal would be known before shipment. Complaints on the severe clinkering of the ash came from only a fraction of the output of the mine but the occurrence of the clinkering seemed quite unpredictable. Attempts to relate the chemical composition of the ash and the fusion temperatures to the clinkering were unsuccessful. Coal from the area of the mine in which the fusion temperature of the ash was the lowest gave the least trouble from clinkering. Chemical analysis of the ash from that section giving the most trouble showed high contents of iron and low contents of silica, but frequently these were not greatly different from those of coals that gave little trouble from clinker. Aside from the clinkering difficulty, the coal was quite satisfactory. The ash content was normal and high rates of burning could be obtained, but again and again such severe clinkering would occur that the furnace would be shut down because of the accumulation of clinker. Examination of the clinker from the customers' plants showed that the clinkers that adhered to the grates and fouled the fuel beds were hard, flat, dense, and usually dark in color. Coal that was satisfactory gave clinkers that were softer, bulky rather than flat, of low density, and usually lighter in color.

Jan 1, 1944

By P. K. Koh, H. A. Lewis, H. F. Graff

New data on the distribution of silicon between slag and carbon-saturated iron at 1600Oand 1700OC are presented which, in combination with previously published data, permit the determination of silica activities over a broad range of compositions in the CaO-Al2O3-SiO2 system. The distribution of silicon between graphite-saturated Fe-Si-C alloys and blast furnace-type slags in equilibrium with CO has been described in previous publications.1"3 In this past work the silica-silicon relation was established at temperatures of 1425" to 1'700°C for slags containing up to 20 pct A12O3. This paper presents the results of additional studies at 1600" and 1700° C which extend the silicon distribution data at these temperatures for CaO-A12O3-SiO, slags over a range from zero pct Al2O3 to saturation with Al2O3, or CaO.2Al2O3. The upper limit of SiO2 is set by the occurrence of Sic as a stable phase when the metal contains 23.0 or 23.7 pct Si at 1600" or 1700°C, respectively. The activity of silica over the expanded range is determined directly from the distribution data.3 Recently4-7 other investigators have studied the activities of SiO, and CaO, principally in the binary system, using different methods and obtaining somewhat different results. EXPERIMENTAL STUDY The experimental apparatus and procedure have been fully described in previous publications.1, 3 Six new series of experimental heats have been made, four at 1600° and two at 1700°C. Master slags of several fixed CaO/Al203 ratios were pre-melted in graphite crucibles, and these were used with additions of silica to prepare the initial slag for each experiment. Slag and metal were stirred at 100 rpm and CO was passed through the furnace at 150 cc per min. The initial sample was taken 1 hr after addition of slag at 1600°C or 1/2 hr after addition at 1700°C. The run was normally continued for 8 hr at 1600°C or 7 hr at 1700°C, and the final sample was taken at the end of this period. Changes in Si and SiO2 content indicate the direction of approach to equilibrium, and in a series of runs where the approach is from both sides this permits approximate location of the equilibrium line. Fig. 1 shows the results of such a series of 15 runs at 1600°C for slags of CaO/Al,O3 = 1.50 by weight. Figs. 2 and 3 record other series at 1600°C and Fig. 5 a series at 1700°C with fixed CaO/Al0 ratios. The results of the experiments at 162003°C have been reported in part in a preliminary note.3 In the experiments recorded in Figs. 4 and 6, the slags were saturated with A12O3 (or with CaO.2A12O3 within its field of stability) by suspending a pure alumina tube in the melt during the course of the run. The final slag analyses were used to establish the liquidus boundaries8 in the stability fields of CaO.2Al2O3 and of Al20,. ACTIVITY OF SILICA The free-energy change in the reaction has been calculated by Fulton and chipman2 from recent and trustworthy data including heats of formation, entropies, and heat capacities. The more recent determination by Olette of the high-temperature enthalpy of liquid silicon is in satisfactory agreement with the values used and therefore requires no revision of the result which is expressed in the equation: SiO2 (crist) + 2C (graph) = Si + 2CO(g.) [1] &F° = + 161,500 - 87.4T The standard state for silica is taken as pure cristobalite and that of Si as the pure liquid metal. Since the melts were made under 1 atm of CO and were graphite-saturated, the equilibrium constant for Eq. [I] reduces to K1 = asi /asio2. The value of this constant is 1.77 at 1600°C and 16.2 at 1700°C. Through K1, the activity of silica in the slag is directly related to the activity of silicon in the equilibrium metal.

Jan 1, 1960

By G. F. Comstock

A serious disagreement as to the effect of titanium on the hardenability of steel exists in published references to this subject. Kramer, Hafner and Toleman reported' that acid-soluble titanium decreased creased the hardenability, with multiplying factors less than unity according to [ ] Grossmann's system for calculating hardenability from the composition. Crafts and Lamont, on the other hand, showed2 how titanium increased the hardenability, with multiplying factors up to nearly 1.7 for about o.' per cent titanium, though reducing the hardenability with higher titanium. Their data, however, were obtained almost exclusively from steels containing more than 2.4 per cent manganese, and thus should be considered as applying mainly to manganese steels. Likewise, the results of Kramer, Hafner and, Toleman regarding titanium are subject to the limitation that although they eliminated the effect of the insoluble titanium compounds from their calculations, they did not make a similar correction for the carbon that was combined with titanium and therefore occurred in a similarly ineffective form. It is suggested by the literature referred to that titanium may have different effects on hardenability, depending on the mode of its occurrence in the steel. The different effects on strength, ductility, etc., have already been discussed by the author.3 In the present discussion some comparisons, on the basis of hardenability as revealed by the Jominy end-quench test, are given between three titanium and two non titanium steels heat-treated in the same ways, and between other titanium steels heat-treated in several different ways. COMPARISON OF PLAIN-CARBON, VANADIUM AND TITANIUM STEELS The five steels used for these experiments were commercially melted and rolled products received in the form of 1.5-in. rounds from three different mills. Their analyses are given in Table I. Steels 2, 3, and 4 are from the same basic electric heat, containing 0.009 per cent of phosphorus and the same amount of sulphur. They were made by, adding aluminum and low-carbon ferrotitanium to different ingots. No. I is a plain-carbon coarse-grained S.A.E. 1040 steel made by the basic open-hearth -process. No. 5

Jan 1, 1945

A new departure of unusual importance in Institute annals was in-augurated by the trip of President Philip N. Moore to the Local Sections at Nevada, Southern California, San Francisco, Seattle, Spokane, Montana, Utah, and Colorado. Everywhere the visit of the President was the occasion of an enthusiastic and successful meeting, which is reflected in the account, published under the different Sections in this and other Bulletins. The President also joined the members of the Columbia Section in their visit to Nelson, British Columbia, at the International Mining Convention, which was attended by mining engineers of Canada and the United States. The President of the Canadian Mining Institute, as well as the officers and members of the Western Section also attended this convention. For full particulars we recommend to our readers the ac- count of this very interesting meeting, which is given on another page of this. Bulletin. It is believed that this is the first meeting between the mining engineers of America and any other country since America joined the Allies. The Secretary of the Institute accompanied the President at the first four meetings and was expecting to attend the others also, but was called home by a death in his family.

Jan 7, 1917

By J. R. Campbell

In order to discuss the subject intelligently, it will be necessary to touch briefly on the forms in which sulphur is supposed to exist in coking coal to be carbonized in beehive or byproduct ovens. Sulphur is known to exist in coal as sulphides and sulphates, as can be determined experimentally. Then there is the so-called organic sulphur, i.e., sulphur in combination with the carbon, 'hydrogen, and oxygen of the coal, about which much has been written, but nothing definitely proven in an experimental way. In fact, so far. as we know, there never has been developed a satisfactory and conclusive method in the laboratory for the direct determination of organic sulphur. For most coking coals, it can be safely assumed that the preponderance of sulphur is in the form of pyrite (FeSz). When exposed to comparatively low temperatures during the coking process, it loses its sulphur according to the following chemical reaction: 7FeS2 = Fe7Ss + 6S. It will be seen, therefore, that six out of the 14 atoms of sulphur (or 42.8 per cent.) are expelled, or volatilized. FelSa remains in the coke as pyrrhotite, or magnetic sulphide of iron; this accounts for the highly magnetic properties of the powdered coke. A more commonly accepted reaction is FeS2 = FeS f S, in which the straight sulphide of iron is produced with 50 per cent. volatilization of sulphur. In the beehive methods of coke making, air is introduced in sufficient amounts to carry on the distilling and the coking processes, and the sulphur is oxidized along with the other volatile products: First, into sulphur dioxide (SO2), known by the pungent andsuffocating odoremitted from the trunnel head; second, into sulphuric anhydride (SOa); and, finally, into sulphuric acid, as it comes into contact with the air and moisture. In a properly regulated draft on a beehive oven, there is never complete combustion of the gases. In other words, the coking process should be carried on in a reducing atmosphere, and a low-grade producer gas kept issuing from the trunnel head. For coals of about 30 per cent. volatile matter, the ratio of air to gas is 3½ to 1. In complete combustion, the ratio is 6 to 1, producing an extremely high temperature

Jan 1, 1916

By H. H. Taft

IT has long been known that the volcanic area south of Belmont, Nye county, Nevada, had mining possibilities. Some of the old-time prospectors knew that gold existed there. Its remoteness from any source of supplies, its long distances from water, the absence of game, and more, perhaps, the lack of grass for animals to subsist upon, has made this an unattractive region in which to search for mines. The decline of the Comstock mines, the exhaustion of sun-dry large and rich ore-bodies, the high cost of mining, marketing, and particularly the ruinously high freight-charges upon refractory ore that had to be shipped to distant smelters, have kept investors out of Nevada for the last few years; and mining people have hardly yet awakened to the importance of Tonopah, Goldfield and perhaps the newer and less developed districts. The discovery of Tonopah by J. L. Butler, who located the Mizpah Claim in May, 1900, and the fortunes soon realized there, attracted many people. As the boom declined, many went away, some scattering out into the surrounding country, and the population is now about 7,000. In the fall of 1902 a discovery of gold was made 23 miles south, in what is now known as the Sandstorm group, 4 miles NW. of Goldfield. In the winter of 1903-4 the Combination, January and Florence mines were discovered, and shipments of high-grade ore soon followed. In January, 1905, there were 10,000 people in Goldfield. In June, 1904, rich gold-ore was found 85 miles SE., at the foot of the south end of the Kawich mountains, but this discovery was kept quiet until a re-location could be made. On August 10, 1904, the Bullfrog claims, and a month later the Ladd mountain and neighboring claims, were located. The Shoshone group was located September 24. This district is

Nov 1, 1905

By W. H. Geis

The following pages summarize the causes that led to the suggestion of unit operation of the paloma field, the organization of com-mittees, preparation of the Paloma Operators Agreement and the reasons for rejection of the plan. Introduction Long ago an Austrian physicist observed that under certain conditions the condensation of a liquid from gaseous mixtures resulted from pressure reduction. Some 50 years later he would have known that his research was not in vain. He would have seen a group of serious operators and engineers seeking to apply that principle to a conservation . program for unitized production in the Paloma gas field—but he would also have been saddened to see that forces unsympathetic to the application of science in oil production, with little or no appreciation of modern methods and the advantages of cooperation, so far have prevented the adoption of that program. Soon after the Paloma field was discovered it was realized that all the hydrocarbons in the reservoir existed in the gaseous phase. This condition was confirmed over a large area. Therefore, if the field was to be properly exploited with the greatest ultimate recovery of condensate, the hydrocarbons in the reservoir must be produced in the single or gas phase. They must be cautiously extracted with the least possible reduction of the natural pressure. If this could be accomplished, or if artificial pressure control were utilized, the condensation and underground loss of the valuable distillate would be preventable—otherwise it would not be. Wholehearted cooperation of all oper-ators was required in order to accomplish the conservation purposes of the program. To this end the production engineers of the several companies concerned lent their time and talents. They fully investigated the physical relationships of the products within the complicated gaseous mixture, prepared extensive reports on the subject and drew up a reasonably efficient plan of operations, which now is commonly called the "Paloma Unit Plan" but actually was entitled "The Paloma Operators Agreement." All of the engineers were not in perfect agreement on all the features of the plan, or even on all the engineering principles. However, it is safe to say that on all the important or essential factors there was a unanimity of opinion, particularly as to the objectives. These were fairly simple and reduce to one controlling item, "pressure control" by cycling or recycling. Organization The principal operators initiated the program by calling a meeting of all the lessees in the area, at which an organization was perfected, known as the "Paloma Operators Committee." Various subcommittees were appointed to expedite the work, including an "Engineering Committee." These func-tioned in a businesslike manner, frequently reported to the superior committee and

Jan 1, 1942

By W. H. Geis

The following pages summarize the causes that led to the suggestion of unit operation of the paloma field, the organization of com-mittees, preparation of the Paloma Operators Agreement and the reasons for rejection of the plan. Introduction Long ago an Austrian physicist observed that under certain conditions the condensation of a liquid from gaseous mixtures resulted from pressure reduction. Some 50 years later he would have known that his research was not in vain. He would have seen a group of serious operators and engineers seeking to apply that principle to a conservation . program for unitized production in the Paloma gas field—but he would also have been saddened to see that forces unsympathetic to the application of science in oil production, with little or no appreciation of modern methods and the advantages of cooperation, so far have prevented the adoption of that program. Soon after the Paloma field was discovered it was realized that all the hydrocarbons in the reservoir existed in the gaseous phase. This condition was confirmed over a large area. Therefore, if the field was to be properly exploited with the greatest ultimate recovery of condensate, the hydrocarbons in the reservoir must be produced in the single or gas phase. They must be cautiously extracted with the least possible reduction of the natural pressure. If this could be accomplished, or if artificial pressure control were utilized, the condensation and underground loss of the valuable distillate would be preventable—otherwise it would not be. Wholehearted cooperation of all oper-ators was required in order to accomplish the conservation purposes of the program. To this end the production engineers of the several companies concerned lent their time and talents. They fully investigated the physical relationships of the products within the complicated gaseous mixture, prepared extensive reports on the subject and drew up a reasonably efficient plan of operations, which now is commonly called the "Paloma Unit Plan" but actually was entitled "The Paloma Operators Agreement." All of the engineers were not in perfect agreement on all the features of the plan, or even on all the engineering principles. However, it is safe to say that on all the important or essential factors there was a unanimity of opinion, particularly as to the objectives. These were fairly simple and reduce to one controlling item, "pressure control" by cycling or recycling. Organization The principal operators initiated the program by calling a meeting of all the lessees in the area, at which an organization was perfected, known as the "Paloma Operators Committee." Various subcommittees were appointed to expedite the work, including an "Engineering Committee." These func-tioned in a businesslike manner, frequently reported to the superior committee and

Jan 1, 1942

By J. S. Fulton

THOSE who live in steel-mill towns are so accustomed to the sight of flames spouting from the mouth of a Bessemer vessel that they seldom pause to think of the amazing process behind it. Actually cold air is being blown through a hot liquid and, instead of cooling it, raises the temperature of the liquid. When coffee is too hot to drink, we know that blowing on it will cool it, so it was no wonder that when Henry Bessemer (or William Kelly, as your patriotism chooses) first proposed this cycle of steel production, he was considered mad. When Bessemer and Kelly started their investigations around 1852, there was not much practical knowledge of metallurgy and, in consequence, there was wide variation in the product made by their process. It was appreciated that the silicon, carbon and iron were all potential fuels, but not until Mushet discovered the beneficial effects of having manganese in the pig iron did the process really become commercial. Bessemer's patent of 1855 covered a crucibleful of liquid iron into which a refractory tuyere was lowered and the blow started. Since that time virtually every conceivable form of vessel, bottom arrangement, tuyere size and location have been suggested or tried. There have been stationary vessels with fixed bottoms, that were side, top or bottom blown; tilting vessels with two sets of side tuyeres at different elevations; vessels like a three-compartment septic tank; vessels of a cylindrical form supported on the long axis with tuyeres along the side submerged by a partial rotation of the vessel (this type continues in copper refineries) ; portable vessels to make the blow in a ladle over a mold in a foundry; a combination of a cupola and converter in one shell, and various other arrangements. But in all these experiments, compressed air for the blast was presupposed and there was little discussion of the quantity or quality of the air delivered to the tuyeres. At one time or another various practices that now are forgotten have been tried or suggested: for instance, the use of inert gas at the end of the blow; the addition of fuel to the blast; the use of hot-blast stoves; the drying of the air to a minimum moisture in the blast. Except in the last-named method little attention was paid to the quality or quantity of the air blown. PHASES Of the many papers published on various phases of the Bessemer process, nearly 170 according to one bibliography, over go per cent were concerned with the metallurgical phase and less than 10 per cent discussed various sections of the pneumatic phase. Since the two phases are coincidental, apparently nine times as much thought has been given to the result as has been given to one of the causes of the Bessemer process. Is it not possible that if more attention had been paid to the pneumatics so many papers would not have had to be written on the troubles in the metallurgical phase? A study of published papers and conversation

Jan 1, 1941

By R. W. Kraft

A back- reflection precession-type X-yay camera for determining the crystallographic orientation of the crystallites of both phases in small areas of thick specimens of polyphase alloys is described ad the geometry, advantages, and limitations of the apparatus are discussed. Metallographic obseg-vations of interfacial angles (or habit planes or growth direction are made on the same specimen so that the crystallographic and metallographzc orientation data call be directly correlated. An example of the application of tile technique to a unidi-~~ectionally solidified CuA12-A1 eutectic specimen is presented. The interfacial planes ad growth directions of each phase were established, and the orientation relationship between the phases was observed and found to be approximately intermediate between two previously reported relationships. The crystallographic interfacial relationship between two solid phases is an important parameter in a variety of metallurgical phenomena because of the energy associated with the interface and because this energy is at least partly associated with the way in which the two space lattices are in contact along the interface. In order to describe the interfacial planes in the crystallites of both phases it is necessary to determine the crystallographic orientation of each phase in a specimen relative to each other, and to directly correlate these data with met-allographic measurements from which the interfacial planes can be determined on the same specimen. The back-reflection Laue technique is the easiest way to determine the orientation of thick single crystals or large grains and the method can be combined with metallographic techniques to provide the necessary data, provided the reflections from each phase can be distinguished from one another. However, if the crystallites are small or of varying orientation or if one or both phases has a unit cell with less than the maximum symmetry, many overlapping and complex Laue patterns are recorded simultaneously and it becomes impractical if not impossible to interpret the photographs. All of these complexities were present in a unidirectionally so- lidified A1-CuA12 eutectic alloy1 for which a crystallographic analysis was desired. Consequently the method described here was developed since no known X-ray or electron diffraction technique had all of the following attributes which were required. 1) Method should yield data from which the crys-tallographic orientation of every crystallite or diffracting unit in the irradiated area can be determined. 2) Method should be adaptable to the study of small areas. Depending upon the degree of preferred orientation in the specimens, it should be possible to obtain reliable data in a reasonable length of time on irradiated areas as small as 1.0 or even 0.1 mm in diam. 3) Method should permit direct correlation of crystallographic data with microscopic orientation data pertaining to crystallite axes, habit, morphology, and growth directions as determined by optical microscopy. 4) method should be such that selected areas of large specimens can be easily studied. Trepanning of a small specimen (such as an electron microscope specimen) from larger specimens was undesirable since it would greatly increase the problem of correlating the crystallographic and microscopic directional data. Requirements 3 and 4 dictated that an X-ray back-reflection pinhole technique should be used on large samples, such as metallographic specimens which had previously been examined and analyzed for their microscopic characteristics. Similarly, requirement 2 could be satisfied by choosing a collimator of appropriately small diameter. Exposure times would not be excessive provided the detector were close enough to the specimen. Because of space limitations film was chosen in preference to a Geiger counter. Requirement 1 was fulfilled by using monochromatic radiation and providing enough additional degrees of freedom in specimen rotation to compensate for Bragg law restrictions on diffracted beams. DESCRIPTION OF APPARATUS The apparatus shown in Fig. 1 consists of a pin-hole collimator, (a), projecting through a rotatable circular film in a holder, (b), which records X-ray reflections in the back-reflection region. The specimen, (c), is mounted on the end of a shaft, (d), which is provided with an adjustment, (e), so that the specimen surface can be placed accurately on

Jan 1, 1962

By R. J. Lloyd

INTRODUCTION The Mount Isa Mine is a large modern underground mine located in North-Western Queensland, Australia. Two ore types are mined and treated separately. Currently silver-lead-zinc ore is mined at the rate of 2.6 million tonnes per annum and copper ore at the rate of 4.6 million tonnes per annum. The silver-lead-zinc orebodies are mined by sub level open stoping and cut and fill methods whilst all copper ore is extracted by various forms of sub level open stoping. The mining operations are highly mechanised and utilise diesel powered load-haul-dump units of various sizes, two and three boom face drilling jumbos, electric-hydraulic rotary-percussive ring drills, in-the-hole hammer drills, rotary blasthole drills, raiseborers, battery/trolley locomotives, a large fleet of rubber tyred service and supply vehicles plus light rockdrills mounted on airlegs, rail mounted overshot shovels and battery and diesel powered locomotives. All stoping production ore is extracted with diesel powered load-haul-dump units. The ore is tipped into orepasses which connect to the main rail haulage levels. On the haulage levels electric battery/trolley locomotives are used to pull rakes of bottom dump or side dump trucks which feed the ore into primary crushers. Following two stage crushing the ore is conveyed to the shaft and hoistod to surface in bottom dump skips. Each ore stream has its own rail transport system, crushing stations and hoisting shaft feeding separate concentrators. This paper will consider some aspects of the role of equipment and machinery in the growth of the mine, will discuss in some detail the machinery and equipment in use today and will conclude with a look at some possible developments in mining equipment for the future, with particular reference to the Mount Isa Mine. A summary of mining equipment in use at Mount Isa is given in the Appendix. THE PAST Silver-lead-zinc ore was discovered at Mount Isa in 1923 and within a very short time many small mines were being developed. However the rich surface ore traces did not continue and by 1928 Mount Isa Mines Limited had acquired sufficient leases to plan for a large scale mine to exploit the low grade orebodies. At this early stage it was recognised that the mine would need to adopt the most mechanised mining techniques then available in order to overcome its twin disadvantages of low graaes and extreme remoteness. The Company introduced bar mounted drifters and overshot shovels to replace hammer and tap and hand shovelling in development work and by 1930 headings were advancing at the rate of 30 metres per week. In keeping with the concept of mechanisation the early engineers designed the Man and Supply shaft with a very large, for those days, cage compartment measuring 3.8 m x 3.4 m. This shaft was the main means of access into the mine for 36 years until the K57 shaft (now R62 shaft) was commissioned in 1966. Man and Supply is still in regular use. Production commenced in 1931 at an annual rate of approximately 660 000 tonnes of silver-lead-zinc ore. The mine was mechanised to an extent which was previously unknown in Australia; whilst the concentrator, smelter and power house utilised the most modern and efficient equipment available. Even so, the mine was very near to closure on several occasions and did not return a dividend to its shareholders for many years. Production levels remained at or slightly below 660 000 tonnes until a separate copper ore streani and mill was commissioned in 1953, doubling the existing production levels. The first underground crushers were installed at this time. Production rates expanded in the years between 1953 and 1973. By 1960 production reached 2740 000 tonnes of ore. In 1965-66 total production was 3650 000 tonnes and in 1973 the production rate plateaued at the current level.

Jan 1, 1981

L. D. GODSHALL, Everett, Washington: This very interesting paper cannot fail to command the attention of every one who has ever had experience in the amalgamation of gold-ores. I wish to call attention to three very important facts brought out very prominently by the paper, namely: 1. The extent of accumulation of amalgam on copper plates in the form of scale, not removable in the ordinary manner; 2. The change in the relative quantity of the two metals in the amalgam as we. recede from the battery-discharge; 3. The difference in fineness of the bullion obtained from the above-mentioned scale as compared with the bullion from the daily clean-ups. From Mr. Bayliss's figures we find that during the life of the plate in question 14,942 tons of ore were crushed, yielding amalgam of the value of $5.03 per ton, or a total value of $75,158.26. The amalgam accumulating on the plate during this time as scale, we find to have had a value of $8340.54, or $0.558 per ton of ore treated, representing 11.09 per cent. of the total amount of amalgam saved in the ordinary clean-up; or, taking the amalgam saved by daily clean-up plus the amalgam-scale as representing the total saved on this plate, or 100 per cent., we find that the daily clean-up saved 90.01 per cent., while the scale represented 9.99 per cent. The above figures do not include some additional amalgam still adhering to the plate after scale had been removed. We are told that this was not an exceptional case at the Drum Lummon, but that other plates have even yielded a third more than the one in question. The interesting query now comes up, whether this experience at the Drum Lummon is exceptional or universal at all mills; and another question arises, as to how long such an accumulation might continue,

Jan 1, 1897

By B. A. Cheadle, C. E. Ells

The ovienlalion of hexagonal a-zirconium crystals in cold-drawn Zircaloy-2 tubes and in both as-extruded and heat-treated Zr-2.5 wt pcl ND tubes has been rrleasured using the inverse Pole - figure technique. Uniaxial tensile tests hare shown the Zil-caloy-2 lubes to hare highly anisotropic delovmation behavior whereas heat-treated Zr-2.5 wt pet Nb tubes are nearly isotropic. The differences in deformation behavior are esbloilred from the observed textures of the tubes and the deformation systems known to oberate in Zircnloy,-3. Tlze vcsults lead to an explanation of the high effective strain observed fov the Zircaloy-2 tubes as colrzpared to heat-treated Zr-2.5 wt pet Nb tubes in restrained end burst tests at 280° to 300°C. THE Zr-2.5 wt pct Nb alloy. when heat-treated by quenching from temperatures slightly below the (a + p)/P phase boundary and subsequently aged at 500°C, has tensile strengths about 50 pct greater than those of 20 pct cold-worked Zircaloy-2.1 There is. therefore, considerable economic incentive to replace Zircaloy-2 with the heat-treated alloy in some in-reactor applications. notably for pressure tubes, where strength is a prime consideration. However, when tubes of Zr-2.5 wt pct Nb fabricated by extrusion and drawing prior to heat treatment were subjected to restrained end-burst tests at 300 °C. the circumferential expansion at failure1 was only 10 pct that of cold-drawn Zircaloy-2 tubes in similar tests,2 Table I. This result was not predicted from uniaxial tensile tests in which the ductilities of the two materials were quite similar.' The detailed requirement for ductility in pressure vessels has not yet been worked out. and comparison of the relative merits of cold-worked Zircaloy-2 and heat-treated Zr-2.5 wt pct Nb is further complicated by the irradiation-induced loss of ductility and hydrogen pickup each will undergo from reactor operation.1,2 Nevertheless. the lower circumferential expansion of the Zr-2.5 wt pct Nb tubes raised serious doubts on the advisability of their use as pressure vessels. For this reason, an investigation to determine the cause for different ductilities of the two types of tubes was initiated. From a study of uniaxial tensile properties and crystallographic orientation it has been found that the fracture ductilities observed in the burst tests can be related directly to the crystallographic ori-

Jan 1, 1965

By D. L. H. Forbes

The application of the cyanide process to complex sulphide ores for the extraction of the gold and silver is no longer a novelty; but, as an example showing modern teudencies in this direction, the following description of the new milling process at the Lucky-Tiger mine is offered: The extraordinary richuess of the ore in the upper workings of this mine made any thought of milling in its early days seem unnecessary. Its location in an almost inaccessible part of the rugged mountains just south of the Arizona boundary-line, and 60 miles from the town of Douglas, made the expense of bringing in machinery and sopplies a very serious consideration. But, after the property had been shipping high-grade ore on mule-back for a few years, there remained in the mine a considerable tonnage of vein-matter that mas too low in value to ship, but which it wag thought could be milled near the mine at a profit. The first milling-experiment consisted in the installation of Nissen stamps in conjunction with concentrating-tables and Frue vanners, but, as the ore from the upper workings contained most of its silver in the form of cerargyrite, this type of mill mas not successful. The proximity of the mine to the great copper-concentrating mills of Cananea and Moctezuma naturally made the influence of copper-milling ideas felt in the company's next instdlation. At considerable expense a stage-crushing concentrating-mill, with a capacity of 100 tons per day, was built. This mill was modeled along the lines of the most approved practice in copper-concentrators at that time, the main idea being that crushing by stages .in rolls was necessary in order to prevent losses from " sliming." Largely owing to the fact that, when the mill

Jan 1, 1913