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By W. S. Burbank, B. S. Butler

STUDY of the ore deposits of Colorado has disclosed, in numerous places, sharp changes in both mineralogy and metal content of the primary or hypogene deposits with change in depth. A clear understanding of the meaning of these changes is requisite to form intelligent conclusions that can be applied in the exploration of such ore deposits. This paper is an attempt to set forth some of the geologic and chemical relations of minerals that bear on this problem. The effect of the differing electrode potentials of elements on the order of oxidation and on the order of displacement of one metal by another metal in supergene sulfide deposits has been studied for many years by several investigators. The results all agree rather closely with the original Shurmann series of replaceability of metal sulfides, as Wells has shown.1 So far as the writers are aware there has been little attempt from the geologist's viewpoint to correlate the electrode potentials of the elements, other than those of the common metals, with the positions and mode of combination of the elements as found in ore deposits, and in particular in hypogene deposits. Wells2 discusses electrochemical activity between solutions and certain ore minerals and mentions the possibility of its effect in precipitation reactions. The senior writer for a number of years has emphasized the importance of oxidation-reduction reactions as a factor in the formation of certain hypogene ore minerals, and as the electrode potentials are a measure of the relative Oxidizing and reducing power of the elements and their ions, it seems possible that a study of them may offer some suggestions on certain problems. The data at present available for such a line of

Jan 1, 1929

By Stephen E. Merritt, John W. Straton, T. Carl Shelton

Surveying and mapping are used to locate and visually portray objects, lines, or areas in relation to a reference point or line. The actual making of the measurements to locate the objects and points falls under surveying while mapping is concerned with putting the survey information into a graphical form. Generally, the type or class of proposed survey depends on the precision required. Some surveys may need only approximate measurements which can be obtained by simply pacing or by using an ordinary measuring tape; others may require much accuracy, thus calling for the use of an engineer's transit or theodolite along with a graduated steel tape for horizontal measurements, or a level and a graduated rod for measuring vertical distances. Mapping is likewise dependent on accuracy requirements. For example, a general layout showing the relative position of surface facilities may not call for a large scale of dimension or great precision whereas for detailed work, a large scale plus care in plotting points and drawing lines and curves are important factors. SURVEYING METHODS There are many kinds or types of surveying methods. Some examples include : land surveying for determining boundaries of land areas; route surveying for locating roads, highways, right-of-way, and haulways; city surveying for laying out lots, streets, and alleys; and mining surveying for projecting mine openings and locating mining operations. See Fig. 1. There are other types of surveying than those named, but in general, the type of method to be used will depend on the purpose for which the survey is to be made.

Jan 1, 1981

By E. R. Hoskins

Results of a primary stress measurement investigation conducted on the 1100 copper ore body of the Mt. Isa mine, Mt. Isa, Queens., Australia, are presented in this chapter. The investigation started in September 1965, after discussion with the engineering staff at Mt. Isa, and consisted of both underground or in-situ tests at Mt. Isa and laboratory tests on Mt. Isa rocks and stress measurement techniques at the Australian National University in Canberra. Underground stress measurements were made in and adjacent to the 1100 copper ore body. The primary stress measurement site was in J 32 west crosscut on 14 Level. Approximate coordinates on the mine grid are 3000 north, 1650 east. The vertical depth below ground surface at this point is approximately 2180 ft. Some preliminary measurements were made in M 30 west crosscut on 13 Level, coordinates 3000 north, 2000 east, depth beneath the surface approximately 1990 ft. Additional flatjacks were installed on 11 Level in L 30 west crosscut, coordinates 3000 north, 2200 east, and depth beneath the surface approximately 1580 ft. All of the sites were in rock that from a mining engineering viewpoint must be considered extremely sound. The 13 and 14 Level crosscuts were approximately 14 ft on a side and nearly square and the 11 Level crosscut was approximately 10 ft on a side. All of the crosscuts had been standing open for several years and no artificial support of any type was necessary. Extraction openings hundreds of feet on a side have been made in this mine in similar rock and these have remained open also without additional support (see Davies 1 for a recent summary of mining techniques and conditions). The geology of the Mt. Isa mine has been most recently described by Bennett.2 Briefly, Mt. Isa is a silver-lead-zinc and copper mine in a series of Precambrian siltstones, shales, and bedded carbonates that strike north-

Jan 1, 1972

By Blamey Stevens

(Butte Meeting, August, 1913.) THE following paper aims to make a full explanation of the phenomena of rock jointing. It may be unnecessary to give any general description of what are termed joints in rocks, but. Professor Geikie's clear and faithful generalizations are so illuminating that no excuse need be given for introducing the following and other quotations into this paper: "Almost all rocks are traversed-by vertical or highly inclined divisional planes termed joints. These have been regarded as clue in some way to contraction during consolidation (fissures of retreat) ; and this is no doubt their origin in innumerable cases. But, on the other hand, their frequent regularity and persistence across materials of very varying texture suggest rather the effects of internal pressure-and-movement within the crust."1 General Explanation.-In this paper I show that the phenomenon of jointing may to a large extent be accounted for by the pressure of the water contained in the pores of the rock. To understand this, each constituent grain of. the porous material may be considered to be separately compressed by the 'water which submerges it. As all the grains are held together by cohesion, the whole mass is contracted by this pressure. In an indefinitely extended mass, however, there must be a limit to the possible contraction without rupture, because the material is restrained from. moving freely by other material around its boundaries. The mass of rock thus becomes broken up. This phenomenon is known as " shrinkage " jointing. The terra "shrinkage" is an apt one, if it be understood that the shrinkage of the rock is often brought about by change of stress. Stresses.-The compressive component of water stress on the individual grains is evidently the same as that of the water with which it is in contact. This is so, both. before and after the jointing is formed. Before the jointing is formed there is, however, a tensile stress in one or more directions which keeps the material from contracting.

Jan 7, 1913

By Clarence W. Balke

Small buttons of fused tantalum have been produced by are fusion in a vacuum, by drawing an arc between sticks of pressed tantalum and a tantalum-faced water-cooled copper block. However, ingots of appreciable size can be produced only by the heat-treatment of bars pressed from powder. The following outline covering the production of finished bars of tantalum by the methods of powder metallurgy is also used for the production of columbium, taking into account the difference in the melting points of these two metals. Pressing the Powder With possibly a few exceptions, a pressing operation is one of the essential steps in the practice of powder metallurgy. In fact, the author's experience with a number of high-melting-point metals and with numerous types of hard carbide compositions has led him to believe that this operation is often one of the most important in the entire process, and frequently one of the most difficult to carry out in a satisfactory manner. Defects due to improper pressing can readily lead to a defective finished product. It is the author's opinion that rarely is a bar or other article pressed from metal powder in such a way that all parts of the piece are uniformly pressed. The nearest approach to uniformity of pressing is possibly attained when the powder is contained in a flexible receptacle, such as rubber, and is pressed under a liquid by hydrostatic pressure. However, this method is not generally applicable. Hydraulic pressing in steel dies where one or two punches are forced into the die must usually be resorted to. As the pressure in such a die is built up, the powder begins to cling to the walls of the die with a tenacity dependent upon the nature of the powder, and this results in a bridging action, so that the layers of powder adjacent to the moving punch are pressed more heavily than those further removed in the mass. Frequently, as the pressure is carried higher, there may be a mass slippage of the powder upon itself, with the result that slip cracks are formed within the pressed

Jan 1, 1938

By F. Kurata, P. C. Davis, T. L. Gore

An experimental method and apparatus for the study of the low-temperature phase and volumetric behavior of volatile mixtures are described. The phase diagrams, including the critical points, and the volumetric behavior of a natural gas and a mixture of the natural gas with methane at temperatures from -40°F to -200°F and pressures to 1.200 11si are givrn. INTRODUCTION Knowledge of the phase and volumetric behavior of mixtures of the light hydrocarbons at low temperatures is becoming increasingly important as interest in low-temperature separation processes increases. Distillation at low-lemperatures has been used for some time to recover ethane and ethylene from natural gas and refinery gas for petrochemical uses. Removal of excess nitrogen from natural gas by distillation has been proposed as a means of increasing the capacity of gas transmission lines and of improving the marketability of the gas.1,2 Evaluation of the latter process has been hampered, however, by the scarcity of data from which the phase behavior of natural gases at low temperatures might be predicted. While existing correlations of vaporization equilibrium constants may be used to predict the behavior of such mixtures at lower pressures, high-pressure computations often require knowledge of the location of the critical point of the system involved. Although correlations have been developed for the prediction of the critical temperature and pressure of certain types of hydrocar-bon systems, they do not apply to very volatile systems such as nitrogen-bear-ing natural gases. This paper describes the initial stages of an investigation of the low-temperature behavior of a numher of natural gases and other gases of commercial interest. The experimental method and apparatus are described. and the phase and volumetric behavior of a natural gas and a mixture of the natural gas with methane are presented. PREVIOUS WORK The published low-temperature vapor-liquid equilibrium data for hydrocarbons and mixtures of hydrocarbons with nitrogen and helium are listed in Table I. Most of these data are for binary systems, and the data of Stutz-man and Brown" at 100 psi are the only data on a natural gas. The data of Bloomer and Parent3 on the methafie-nitrogen system, which have been phblished since this study was completed, are a valuable addition to the knowledge in this field. Prior to the publication of these data the only published critical point data on systems having critical temperatures below the ice point were those of Ruhemann.1 on the methane-

Jan 1, 1952

By P. H. Dudley

I have taken the liberty of calling the researches herein mentioned industrial, to distinguish them from those strictly scientific, where every known appliance is used to insure accuracy in determining principles. The industrial researches are made to ascertain wherein we have failed to embody, in practice, the principles which have been fully demonstrated by the more purely scientific investigations. So far the researches have been mostly confined to the conditions of combustion as used in locomotive furnaces, although we have examined, to some extent, furnaces under marine and stationary boilers. The products of complete combustion are gases, and, knowing what we should have, it is at once shown by analyzing the products whether the desired reactions are taking place. In spite of imperfect furnaces, lack of system in the arrangement of grate-bars and exhaust nozzles, the results are not altogether vitiated, because the analyses are not closer than one-tenth of one per cent., as under the present conditions it is hardly possible to collect gas exactly under the same conditions at different times. All of 'our industrial operations have developed in the past few years so rapidly, nearly all of them paying, that,, until within the past three years, comparatively little attention has been given to their economy outside of the profession. Great corporations have not asked and considered the question in earnest, can we utilize our heat so as to produce the same effect at less cost? The applications of heat are so extensive, entering into every branch of industry, the principal power used to carry on metallurgical processes, to conduct transportation, that its econonlical generation becomes of universal importance; in fact, its economical generation and application is the leading industrial question of the day. It is stated by those who have given the subject much attention, that in our best steam-engines not over 10 per cent of the theoretical value of the fuel is utilized, and upon locomotives it is far less, probably not exceeding under the most favorable circumstances 5 or 6 per cent. In recent experiments made with the dynagraph, in drawing trains upon the Lake Shore and Michigan Southern Railway from Cleveland to Erie, 941/2 miles, we found the force required to draw a stock train of 709 tons to be 2,498,396,320 footpounds, exclusive of the force to move the locomotive itself. We

By G. A. Reinhardt, H. J. Cutler

ThE Youngstown Sheet & Tube Co. has produced a large tonnage of 0.35 to 0.45 carbon forging steel, the acceptance of which was based on the physical properties of test specimens obtained by forging the original 5 3/4-in. (14.5 cm.) square bloom to a 3/4-in. (1.9 cm.) round. Annealed and tempered specimens were required. The test bars were annealed by heating from 900" to 950' C. and cooling slowly in mica. The test bars were tempered by heating to 825' to 875" C., quenching in water, and drawing to 515" to 535" C. Immediately after heat treatment, the test pieces were machined to a diameter of 0.534 in. (1.38 cm.) and tested. Very good physical properties were obtained and no difficulty was experienced in meeting the specifications called for. UlTimate Strength.. Elongation, Lb. pER Sq. In. PEE Cent.. in 4 In. Not LeEs Than Annealed specimens.............. 78,230 to 92,450. 18 Tempered...................... 120,000 to 149,350 9 After experience on this material, production of slightly higher carbon forging steel was started. The method of testing this material required that test blooms be either normalized or annealed. The normalizing consisted in heating to 850" to 900" C. and cooling in still air; the annealing, in heating to 850" to 900" C. and cooling in the furnace or in mica. From the treated bloom, the test pieces were taken either by core drilling or by sawing from points midway between the edges and the intersection of the diagonals. The cores or blocks were turned to a standard 2-in. test piece with a diameter of 0.564 in. and tested without further treatment. The physical requirements of the test pieces were: yield point, pounds per square inch minimum, 44,800; ultimate strength, pounds per square inch, 89,600 to 112,000; elongation, per cent. in 2 in. not less than 17. Difficulty was encountered as soon as work on this material was started. Many precautions and refinements were instituted but it was found very difficult to secure the required elongation.

Jan 1, 1920

By J. Lyndon Rosenblad

This chapter describes the development of a rocklike model material for use in tests with a rock-blocks model to investigate the failure mechanism of a discontinuum. In order to provide reliable results, the model material must be characteristic of natural rock and obey the laws of similitude. Initially, the development of such a material does not appear to be a difficult problem. Only when one undertakes such a task does he realize how little is actually known, and that there is considerable work yet to be done. A material that simulates rock in all of its physical properties probably will never be developed. There is now and probably always will be room for improvement. Improvement is needed not only in the component materials but also in the technique of preparation. The material developed and subsequently described in this chapter simulates rock in general and a schistose gneiss rock in particular. The material possesses many rocklike physical properties not found in previously used model materials. One of the most significant improvements of this material is that there is an increase of Young's modulus with an increase in confining pressure as determined by triaxial compression tests. A change in the usual procedure of material preparation was used to develop this material and is also described. MODEL MATERIALS USED IN THE PAST Intact Materials Numerous materials have been used by investigators in models in the past to simulate a wide range of prototype materials. Some of the materials used include cork, plastic, concrete, plaster of Paris, portland

Jan 1, 1972

By Paul T. Allsman

1.1-1. Current Status. The history of surface mining is essentially that of mining coal, copper, and iron ores, and the nonmetallic minerals--clays, gypsum, phosphate rock, sand, gravel, and stone. Table 1.1-1 is a comparison of the estimated world production of crude metallic and nonmetallic ores and coal with that of the United States for 1964, in short tons. It includes an estimate of the quantity produced by surface mining methods. Two-thirds of the 8.8 billion tons are mined from surface, ranging from a third of the coal, half the metallic ores, and nearly all clays, stone, sand, and gravel. In the United States, production by surface methods parallels that of the world with two major exceptions: 74% of copper ore and 90% of usable iron ore are mined from the surface, whereas outside the country less than 40% of copper ore and only 50% of usable iron ore are mined from the surface. In surface mining of both metallic ores and coal, much waste is stripped, but in mining nonmetallics the ratio between waste and ore is small. Assuming that the stripping ratio for surface mining in the United States will apply equally to world production, it is estimated on a weighted basis that over 21 billion tons of waste, or a total of nearly 27 billion short tons of material, are mined annually in the world by surface methods. Data are not available to confirm the assumption for waste stripping outside the U.S., but the estimate expresses an order of magnitude that is worth noting. Table 1.1-2 shows the materials-crude ore, coal, and waste-mined by surface methods and the relation to total mined by both surface and under- ground methods in the United States during 1964. Eighty-two percent of all crude metallic and nonmetallic ores and coal was mined from the sur- face, including 82% of metallic, 96% of nonmetallic ores, and 35% of coal. Copper and iron ore comprise 83% of the metallic ores mined from the surface, and clays, gypsum, phosphate rock, sand, gravel, and stone

Jan 1, 1968

By R. A. Matuszak

This paper discusses the major portion of the hoist (drag or crowd) system and it shows how static control accomplishes its major aims. In 1959, the first truly static control for Ward-Leonard equipped electric excavators was designed, developed and placed in service. The control system, originally intended only as a more modern electronic type of alternate to the proven rotating amplifier control system has since proven to be much more. When they conceived the original system, the designers had much more in mind than simply replacing the rotating amplifier with one that had no moving parts. The long range plan, which started with the initial system consisting of an SCR (silicon controlled rectifier) preamplifier and magnetic amplifier power amplifier, called for eventually, a control system low in cost and maintenance, relatively simple in design and extremely reliable. The plan also included the elimination of as many of the shortcomings of the rotating system as possible. No small accomplishment, when it is considered that the rotating control system had been, with only minor modifications, the standard of the industry for 20 years. The final step in the original design plan called for the eventual development of an amplifier that could be used as one of the basic building blocks of the future. DEVELOPMENT RESULTS Since the successful unveiling of the first static control system, continuous development has resulted in a slow, but sure progression along the path described by the original plan. The first version of the new control corrected one of the shortcomings of the rotating system by removing the necessity of operator anticipation. This was accomplished by making the system faster in response so that the operator noticed virtually no delay between his movement of the master controller and that of the machine. Thus, after the operator became familiar with the operating characteristics of the machine, he was able to become more relaxed while digging. The natural result of this accomplishment was higher production. All of the subsequent versions of this new control were even faster than the initial design. Although it was not distinguishable by the operator, the further increase in response resulted in large gains in the limiting of transient torque peaks applied to the machine while digging. Also, a more effective control of the torque and power peaks was obtained when plugging the motion being controlled to a stop. (Plugging is the use of the Ward-Leonard ability to regenerate power and absorb energy from the load to

Jan 1, 1964

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 Boyd Dudley

The material presented in this paper is an abstract of a thesis submitted by the writer to the faculty of the Massachusetts Institute of Technology, as part requirement for the degree of Master of Science. The investigation was undertaken at the suggestion of Prof. H. 0. Hofman, and it was conducted, under his direction, in the laboratories of the Mining Department of the Institute. The purpose of the work was, first, to study some of the reactions that have been considered as a part of the mechanism of the chloridiz-ing roast, and second, to study the conditions under which nickel oxide and copper oxide may be chloridized. While the production of chlorine gas by various reactions during the chloridizing roast may not be primarily useful in the chloridation of metal oxides and compounds, it nevertheless serves a useful purpose in preventing the dissociation and decomposition of chlorides once they have been formed; for example, the dissociation of cupric chloride into cuprous chloride and chlorine. Therefore it was thought that a study of some chlorine-producing reactions would prove of interest, and the first series of experiments dealt with this phase of the subject. he object of the latter part of the work was to show the possibility of treating heavy sulphide ores, such as those of Sudbury, Ontario, containing much iron and small amounts of copper and nickel, by chloridizing and removing the copper, leaving an iron-nickel oxide product suitable for smelting in the blast furnace for nickel-bearing pig iron. The chloridizing of the copper would, of course, be preceded by a roast for the removal of sulphur, the sulphur oxides being available for the manufacture of sulphuric acid, if under the local conditions this product would be of commercial value. Reactions of the Chloridizing Roast Reaction of Sodium Chloride, Sulphur Trioxide, and Oxygen.—The first reaction studied was that involving the production of chlorine

Jan 1, 1915

By C. C. Henning

In any line of human activity logical handling requires an amount of attention to each phase that is in keeping with the importance of that phase. In the complex and rapidly changing field of modern ferrous metallurgy it is difficult to allot the proper degree of attention to the various subjects, and it is not surprising that one or more subjects of major importance should for a time be neglected. Bessemer steel is a good example of a neglected subject. It is largely taken for granted, inferior physical quality is assumed for it, and there is a • lack of interest in its technical development and commercial application. Availability of supply is limited. In spite of this technical indifference, limited source and lack of commercial exploitation, bessemer steel constitutes a large volume of tonnage in daily use. There is a fairly prevalent idea even among technical people that bessemer steel survives mostly because of low cost and by reason of a dwindling residue of applications sufficiently common to permit of its use. The difference in cost between bessemer and open-hearth steel is governed largely by the relative cost of manufacture of pig iron and the market price of steel scrap. During the past four years there have been long periods of time during which the price of steel scrap was low enough so that open-hearth steel was considerably lower in manufacturing cost than bessemer. As to application, it may be pointed out that thousands of tons of this material in the form of bessemer screw steel are applied for moving parts in automotive and other equipment. Some forging work and considerable heat-treating, particularly carburizing, is performed on this grade. From an economic standpoint the most effective contribution of bessemer steel lies in its free machining qualities. It is by far the freest

Jan 1, 1935

By Frank C. Appleyard

The two calcium sulfate minerals-gypsum and anhydrite-occur in many parts of the world, and gypsum has long been of economic importance in the family of industrial minerals. Gypsum, the dihydrate form of calcium sulfate (CaS042H20) and anhydrite, the anhydrous form (CaSO4) are frequently found in close association, and it is seldom that a calcium sulfate deposit will consist exclusively of one mineral or the other. Although known gypsum deposits are extensive, anhydrite makes up the largest part of total calcium sulfate reserves. However, it has very minor economic use, and most of the following discussion will be devoted to gypsum. Calcium sulfate is one of the principal con- stituents of evaporite deposits, and when pure, has the following composition: [ ] Deposits of pure gypsum or of pure anhydrite which are large enough to be considered commercial have never been found because of both the metastable relationship between the two minerals, and the presence of impurities such as calcium or magnesium carbonates, chlorides, other sulfate minerals, clay minerals, or silica. As a result most mine production of gypsum will range between 85 and 95% pure. Often it is used as mined, although in certain cases, one or more forms of mineral beneficiation are employed to upgrade the product.

Jan 1, 1975

By J. H. Hamilton, J. R. Lewis, J. C. Nixon, C. L. Graverson

Recently there has been much speculation concerning the advantages of using oxygen enriched air or pure oxygen in pyrometallurgical processes. The advantage of using oxygen in the iron blast furnace and elsewhere in ferrous production metallurgy has been given careful consideration and, as a result, several experiments have been tried and a number of papers have recently appeared on this subject.1,2 The use of oxygen in nonferrous smelting likewise poses interesting problems, therefore any experimental data obtained in this area should likewise be of general interest.3 Ashcroft4 in 1933 claimed to have obtained improved results when copper concentrates were roasted in pure oxygen. However, his paper gives neither data nor experimental details. A few years ago a research program was started in this laboratory which had for its objective the determination of the mechanism of oxidation of metallic sulphides under varying conditions. To date we have studied the oxidation of galena,5 sphalerite, and chalcocite. It is a well known fact that copper sul-phde minerals are oxidized slowly by weathering agents, so that the sulphides of copper which find their way into a tailing pond are gradually changed into water-soluble and acid-soluble compounds. Commercially, the oxidation of copper sulphide minerals is accomplished by roasting them at elevated temperatures in air using a suitable (usually multiple hearth) roaster. Most copper smelters are equipped with such roasters. In this phase of the study we were especially interested in determining the effect of temperature on: (I) the air oxidation of chalcocite and (2) the oxidation of chalcocite using commercial oxygen. The amount of sulphur removed as sulphur dioxide, the percentages of water-soluble copper, and of acid-soluble copper were determined for the air oxidation tests. In the tests using commercial oxygen, the percentages of sulphur dioxide, water-soluble copper, acid-soluble copper, water-soluble sulphur and acid-soluble sulphur were determined. For these experiments the temperature was varied from 250 to 700°C. Experimental Preparalion of Chalcocite (Cu2S) Natural chalcocite is not pure, Minerals such as bornite, covellite, and chalcopy-rite may be present. It was decided, therefore, to prepare some chalcocite in our own laboratory. An intimate mixture of sulphur and hool divided metallic copper in the ratio of 4 g of copper to I g of sulphur was prepared. TO this was added a slight excess of

Jan 1, 1949

By Walter Miller

Crude oil stocks were some 10,000,000 bbl higher on June I, 1947, than at any time during 1946 but the extremely heavy refinery runs the last half of 1947 cut crude inventories to approximately the 1946 closing level of 225,000,000 bbl. Many refiners were seriously short of crude oil during the year. This shortage was reflected in numerous advances in the posted price of crude, justified in part as an incentive for more production but more generally due to competitive bidding. Some purchasers of crude, endeavoring to keep their plants running, resorted to the payment, either directly or indirectly, of premiums above the posted price. Another common practice employed by some suppliers of crude oil was to demand refined products in exchange or trade for their raw material. The refined products picture has darkened in spite of record throughputs. Stocks of gasoline and light and heavy fuel oils were uncomfortably low at the beginning of the year and were in general still lower at the close. The rationing of some products, principally gasoline, to dealers and stations? initiated during the year, gained momentum as stocks continued to diminish. The emphasis placed by the manufacturers of oil-burning equipment on the convenience and economy of heating with oil, together with the tight situation in coal, has developed a tremendous demand for burning oils. Consumption of liquefied petroleum gas for domestic and household fuel had more than doubled in 1946 over 1943, and the demand seems to be limited only by the ability of the equipment builders to furnish necessary storage. transportation, and burning equipment. The supply situation is likely to become more acute in 1948. Demand for petroleum products is being pushed to new heights not only by the unprecedented domestic market but by a sudden and drastic upswing in estimates of military and governmental requirements. Additionally, oil exports are running far below the volume requested, amounting to less than forty percent in a recent quarter, and export licenses are reportedly being approved on the basis of urgent need *only. AX recent White House release sees little likelihood that estimated requirements of the sixteen nations participating in the proposed Marshall Plan can be met in full over its projected life—1948 to 1951. Present demand dictates maintenance of refinery operations at the highest possible level and the Bureau of Mines has forecast daily average crude runs in 1948 of 5,265,000 bbl. The Economics Advisory Committee of the Interstate Oil Compact Commission recently estimated the 1948 demand for petroleum products at nearly 6 pct above 1947. They further estimate daily average crude runs of 5,375,000 bbl in 1948, some 2 pct higher than forecast by the Bureau of Mines. Projected demand exceeds supply to the extent that Capitol Hill is reportedly investigating ways of enabling oil companies to act in concert without danger of antitrust prosecution, such as elimination of crosshauls, pooling of products, and lowering of octane.

Jan 1, 1948

The first mention of the mining and use of coal in the Pittsburgh district refers to the mine under Duquesne Heights that furnished coal for the garrison at the fort at Pittsburgh in 1760. Coal had been dug and used as fuel just outside of Brownsville, Fayette county, in 1759, but this was not a regular mine as the opening was in an outcropping. Maps of Ohio in 1770 showed "Cole Mines" at various points. The Penns purchased all the coal south of Kittanning in southwestern Pennsylvania from the Chiefs of the Six Nations for a reported price of $10,000. During the Revolution, coal from Herron Hill, Mincrsville, and Coal Hill, all within the present city limits, was used in Pittsburgh. There is today one custom pit opened in Coal Hill (Duquesne Heights). The first steam engine was set up in Pittsburgh in 1794 and used coal as fuel. The first mine in the Youghiogheny gas district was opened in 1796. In 1803, the first shipment of coal by water was made from Pittsburgh down the Ohio river and landed at Philadelphia, where it sold for approximately $9.50 per ton. The mines along the Monongahela were naturally the first to be opened. With the completion of locks and dams in 1844, permitting slack-water navigation, the industry began to thrive. The No. 8 field of Ohio and the Fairmont region of northern West Virginia were opened in the period 1840 to 1855. From that time on there has been a continuous development of the coal rcsources of this district, until at present productive capacity is enough to supply 30 per cent. of the country's needs of bituminous coal. The original method of working the Pittsburgh seam was to drive under cover at some easily accessible point on the outcrop with a single entry, usually 1½ yd. wide. Rooms or gangways were turned to the right and left from this entry and ventilation was usually poor and inade-

Jan 1, 1927

OUTSTANDING symbol of the machine age, the steam shovel needs no introduction. Few individuals there are, in the United States at least, that have not watched with fascination the almost human motion, the more than human strength, the rhythm of the whole steam-shovel cycle of crowding, digging, swinging, dumping, swinging, and crowding again. A mass of steel with some copper and other metals, fed with water and coal, guided by a single alert and dexterous operator, or perhaps two, does the work that would require 50 to 500 men or even more. The largest shovels working in the copper mines have loaded into waiting railway cars as much as 10,000 tons of ore in a single 8-hour shift. With no equipment but hand shovels, it would, in fact, be impossible to duplicate the work with any number of men; first, because they would be in each other's way, and second, because the steam shovel can lift single pieces of rock weighing 5 or 10 tons with effortless ease. Of recent years, internal-combustion engines and electric motors have displaced steam as a motive power in many instances; and of course the detailed design of the shovels has been improved immensely. Whereas the largest dippers used 30 years ago had a capacity of 3 ½ to 4 cu. yd., today the 350-ton shovel used at Chino has an 8-yd. dipper, as has the 320-ton shovel at Chuquicamata. Incidentally, for stripping at coal mines a shovel having an 18-yd. dipper is in use. However, the principle of operation of the modern shovel, regardless of the size and type of motive power, is essentially the same as that of the earlier shovels. It is fair to say that the indispensable of open-cut mining is the steam shovel, or, to be more precise, if perhaps less picturesque, the power shovel. Somehow the electric shovel seems to lack the glamour that

Jan 1, 1933

By L. G. Austin

The procedure for scaling breakage parameters determined in a laboratory mill to values for a full-scale mill is briefly presented. A simulation model of a closed circuit mill also requires a model of residence time distribution, a mass transfer law to predict over-filling as a function of flow rate through the mill, and a model to describe classification action. For fine dry grinding, or viscous slurry grinding, it is necessary to allow for slowing-down of breakage rates for a fine mill charge. Four examples of comparing simulation models to actual plant data are presented. The first is wet grinding of copper ore in normal closed circuit at 50 tph (metric) production, under conditions where the mill does not overfill. The second is the wet grinding of copper ore in reversed closed circuit at production of 87, 102 and 108 tph, with flow through the mill of approximately 150, 200 and 300 tph. The third is dry grinding of coal with a hot air sweeping stream to remove all of the coal as air-borne material, in open and normal closed circuit. The fourth is grinding of cement clinker in a two-compartment, air-swept tube mill in normal closed circuit with two different classifiers, producing 120 tph of 3250 Blaine cement. In all cases the simulated capacities and product size distributions were in reasonable agreement with actual plant performance.

Jan 1, 1984