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All the TECHNICAL PUBLICATIONS and CONTRIBUTIONS published in 1938 are available at Institute headquarters, unless otherwise noted. They are also on file in many public, university and technical libraries and, when so indicated in the list, may be found in the TRANSACTIONS. TECHNICAL PUBLICATIONS in Classes A-Metal A-Lining, B-Milling and Concen-tration, H-Industrial Minerals, and I-Mining Geology are distributed in MINING TECHNOLOGY, which is issued every other month. Technical Publications in Classes C-Iron and Steel Division, D-Nonferrous Metallurgy and E-Institute of Metals Division are distributed in METALS TECHNOLOGY, which is issued twice quarterly. TECHNICAL PUBLICATIONS ill Class G-Petroleum Division are distributed in PETRO-LEUM TECHNOLOGY, which is issued quarterly. TECHNICAL PUBLICATIONS in Classes F-Coal Division, .l-Mineral Industry Education Division, K-Mining Administra-tion, and L-Geophysical Methods of Exploration are issued as separate pamphlets. All Institute member is entitled to one copy of any TECHNICAL PUBLICATION or CON-TRIBUTION. Copies of TECHNICAL PUBLICATIONS listed have been mailed to members of the Institute according to their registration by classes. CONTRIBUTIONS and other TECHNICAL PUBLICATIONS will he sent upon request. A member may purchase an additional copy of a TECHNICAL PUBLICATION or a CONTRIBUTION at one cent. a page; in minimum charge, 256. If the TECHNICAL PUBLICATION has been published in METALS TECHNOLOGY, MINING TECHNOLOGY or PETROLEUM TECHNOLOGY, the number of either magazine containing it will be supplied at the sae cent a page (minimum charge, 25¢) rate for the particular TECHNICAL PUBLICATION requested. Nonmembers may purchase any CONTRIBUTION or a TECHNICAL PUBLICATION Of the F, J, K, or L classes at the same rate, butt the nonmember price per copy for METALS TECHNOLOGY, MINING TECHNOLOGY or PETROLEUM TECHNOLOGY is $1. TECHNICAL PUBLICATIONS (Separate pamphlet form), $2 per annum; Canadian and foreign postage 50 cents extra. METALS TECHNOLOGY, $7 per annum; Canadian and foreign postage 50 cents extra (Iron and Steel Division and Institute of Metals Division ferrous and nonferrous papers). MINING TECHNOLOGY, $6 per annum; Canadian and foreign postage 50 cents extra (metal mining, milling and concentration, Industrial Minerals Division, and mining geology papers). PETROLEUM TECHNOLOGY, $4 per annum; Canadian and foreign postage 50 cents extra.

Jan 1, 1938

By Leslie W. Austin

ROTARY kiln operators will agree that some of the most severe conditions a refractory must stand occur in the hot zone of a kiln burning Portland cement, dead burn dolomite, magnesite, periclase, and similar materials. Frequently the operator is faced with factors beyond his control which drastically shorten the life of refractories. Shutdown due to mechanical failure can be serious if the period is of sufficiently long duration to cause the dropping of coating or the loosening of the lining. A change in slurry can affect the coating and cause ring buildup. A change in type of fuel and its effect upon the flame can cause a shift in location of the hottest zone. Weekend shutdowns or any other interruption can cause the operator trouble and may damage the refractories, since stopping and starting a rotary kiln is certainly more difficult than stopping and starting a motor. Some operators have tried to set an estimate of damage for each shutdown in equivalent days of running time. Conditions affecting the refractory may be roughly grouped in four classes: chemical attack, mechanical stress, thermal shock, and abrasion. Chemical Attack: The drive to obtain maximum production through a kiln demands maximum operating temperatures, temperatures which are limited more by the ringing up or melting of the clinker. This can cause interface temperatures at the junction of coating and refractory which require the use of a basic kiln block to withstand the chemical attack. Chemical changes take place within the refractory itself, especially in chemically bonded or unburned kiln blocks: These changes cause the formation of the ceramic or burned bond. Migrating liquids or fluxes from the kiln charge have an effect within the refractory and lead to mineral or glass formation. The alkalies, sodium and potassium, migrate into the refractory as silicates, chlorides, sulphates or other salts. They may move under capillary action or may be caused to move by volatilization with condensation in the cooler portion. Mechanical Stress: Concentrated stress may be caused by several factors or combinations thereof. 1-The rings of refractories must be kept tight and rigid within the kiln, and this alone demands considerable force to hold the blocks in place. So that the force will not be concentrated, the blocks should fit the circle as perfectly as possible, with the faces in contact overall. 2-As the kiln is heated, thermal expansion takes place at the hot end of the kiln block. Since this disturbs the plane face it too can cause a concentrated stress at the two ends of the block, and shearing stress can be set up within the brick itself because of the difference in expansion between the two ends. 3-If a lining becomes loose and moves in the shell very severe stress can be set up, and as the kiln rotates this load changes and gives the effect of repeated loading. Permanent expansion of the refractory can also cause severe loading. 4-Not least important, flexing of the kiln is frequently the cause of concentrated stresses. Thermal Shock: Thermal shock, the result of heating and cooling too rapidly, occurs on starting and stopping or when a large patch of coating drops, exposing the bricks. Again, its destructive effect is often the result of phase change, liquid to solid or the reverse; dense refractories loaded with glass-forming impurities are particularly susceptible. Thermal shock is a problem with refractories set in the wall or roof of a stationary furnace, and becomes even more serious in a rotary kiln, the tendency to spall being magnified with movement and concentration of stress. Uniform rate of feed and loading insures both better coating and a more uniform stress. Abrasion: If the refractories do not take a coating, abrasion can become a most destructive factor. Movement of the lining in shell or movement of loose blocks causes abrasion, which is also most destructive if the refractories do not take a coating. An analysis of the problem of basic lining for the hot zone reveals, therefore, a number of desirable characteristics: high refractoriness, basic chemical reaction, resistance to spalling, good strength at all stages, ability to take coating, true sizing, volume stability, and abrasion resistance. Increased demand

Jan 1, 1952

By E. C. Weichel

THERE have been many attempts at permanent roof support in anthracite mines, in some cases brick arches, in others concrete, and also combinations of brick or concrete walls with steel beams. These supposedly permanent roof supports have frequently failed when heavy pressure is brought to bear upon the structure, because they are so rigid that failure occurs because the structure is unable to adjust itself to the increased load. Roof pressure exerts a tremendous weight, and it is at times difficult to find any means of support which is strong enough to bear the entire pressure, unless this supporting structure has in itself the element of some flexibility which will enable the structure to hold the moving mass until it "arches" itself. If the supporting medium has flexibility enough so that it can adjust itself to the heavy initial loads, and so give the overlying material an opportunity to form a self-supporting arch, then such a roof support will be more useful than any rigid roof support. There has recently been introduced into the anthracite region a new form of gangway lining that is flexible enough to slightly adjust itself under heavy pressures, and so give the loosened material which is being supported a chance to form into an "arched" mass. This lining, manufactured under patents granted to Hans Schaefer of Essen, Germany, was introduced in the United States in the summer of 1928, at which time the Amercan licensee, Richard Howells of

Jan 1, 1930

By Morris Steinberg, John Wulff, Robert Kamm

IN powder metallurgy it has often been observed that shrinkage may occur in one direction and growth in another during sintering. Even in long-time sintering experiments the rate of shrinkage may be different in different parts of the compact. In the fabrication of some parts requiring a constant permeability it is even questionable in some cases whether pressing from one direction should be attempted. These observations require for their interpretation a more detailed study of green or pressed density than has heretofore been available. Usually average density measurements of the whole compact are made and in some cases carefully cut sections are measured. A different approach to the problem was first mentioned by Rakowski1 and also used by Balshin.2 Balshin's diagram is reproduced in Fig r and schematically shows the result of pressing three layers of metal powder with fine intervening layers of graphite. The retarding effect of the die walls and a qualitative example of the density distribution is evident. More quantitative information about the distribution of density within a cold-pressed powder compact would be useful in showing the variation in density in compacts as influenced by the type of powder, shape of die, lubrication during the process, and other variables. Furthermore, information about the cracking of cold-pressed compacts may be obtained from an analysis of the stress distribution within a powder compact, and some information about the stress distribution can be obtained in turn from the density and strain distributions. A more detailed report on some of the present experiments appears in reference 3. PRESENT INVESTIGATION In order to ascertain the density gradients in cold-pressed metal powders, a deformable lead grid within the powder was employed. After pressing in cylindrical dies the ejected compact was radiographed, giving a pattern of the deformed grid. From the radiograph density and deformation from point to point is readily measured. From the radiograph strain distribution and stress trajectories were also determined. The latter also permits the determination of the coefficient of friction at the die wall. This technique indicates that the densest part of a compact pressed from one side is at the top outer circumference and the least dense region at the bottom circumference near the stationary plunger. For some heights of compacts the density at the axis is such that the lower density is at the top rather than at the bottom. So irregular a density distribution is due primarily to die-wall friction. As the ratio of diameter to height of compact is increased the die walls play a correspond¬ingly smaller role. More uniform density

Jan 1, 1947

By F. Keller, R. H. Brown

BECAUSE of the extensive use of Alclad 24s alloy sheet in aircraft construction, there is much interest in the metallurgical changes caused by heat-treatment of this product.1,2 One of these changes is the result of the diffusion of soluble elements from the core into the coating during treatment. This paper deals with the thermal treatments that may influence diffusion and with the practical effects of diffusion on the serviceability of the product. As is well known, Alclad 24s-T sheet has a core of high-strength alloy combined with surface layers of relatively pure aluminum. The microstructure of a cross section of this product is shown by Fig. I. hot only does the relatively high-purity coating have a high resistance to corrosion, and hence serves as a mechanical barrier between the core metal and the corroding environment, but in addition this coating I exerts electrochemical protection over areas where the core may be exposed, such as cut edges. In addition, the coating affords electrochemical protection to projecting heads of *417S-T, 17S-T and 24S-T rivets, or attached members made from these alloys. Under some conditions of heat-treatment, however, diffusion of copper into the coating will alter the electrochemical relationship between the coating and the core to the extent that only partial protection will be obtained under some corrosive conditions. The reason for the electrochemical protection lies in the fact that the coating layers of pure aluminum are anodic to the alloy core. The addition of copper to aluminum produces alloys in which the potential is lower than that of the pure metal. Moreover, as the amount of copper in solid solution in z4S alloy is increased, the potential of the alloy becomes more cathodic. When heat-treated at 920°F. and quenched in cold water, 24s-T is about 0.16 volt cathodic to pure aluminum. However, copper will diffuse from the core into the coating, and if it reaches the surface the potential will be altered in a cathodic direction. Thus the potential dif-erence between the core and coating may be less than 0.16 volt, depending upon the thickness of the coating, and the time and temperature of heat-treatment. Of the methods available for determining the extent of diffusion of copper from the core into the coating of Alclad 24S-T, two are generally used; namely, the metallographic and the solution potential method.3 METALLOGRAPHIC METHODS Metallographic methods will reveal the progress of diffusion of copper into the coating. For instance, the diffusion zone in the coating intermediate between the coating surface and the core is shown in Fig. I. This photomicrograph is of a polished and etched cross section of 0.040-in. Alclad 24S-T sheet. Diffusion proceeds into the coating more rapidly along the grain boundaries than through the body of the grains. consequently, the diffusion zone is not of uniform width

Jan 1, 1944

By Henry Morris

AS STATED last year, in a similar review by David White and the author, any review of the petroleum industry purporting to cover such a wide field can only mention the principal facts. This incompleteness is necessitated not only by the limitations of space, but by the delay in receiving detailed information. The principal feature of the year, in Europe, was a material increase in the consumption of petroleum products, and a notable decline in prices. Although there we relative increases in production in Roumania and Poland, the total did not by any means keep pace with the increase in consumption, which, as usual, was supplied "from America and both the Near and Far East. The interest in Asiatic production, as usual, centers around the Persian fields, which, according to the annual report of the Anglo-Persian Oil Co. published at the close of last year, it was estimated would amount to 3,775,000 tons by the close of the fiscal year, March 1, 1924. Russia also showed an increase in production. In Africa there was nothing of outstanding interest in production, although Egypt showed a decrease and the goverment refinery at Port Said was closed.

Jan 3, 1924

By Leon Dominian

I. INTRODUCTION APART from local needs in the country's development, the interest attached to Turkish fuels grows chiefly out of the importance of the railway industry in Asiatic Turkey. Geographical conditions make of the tracks in this region the most essential link in a chain of world-girdling lines. By its position Asia Minor can be likened to a bridge in the through routes destined to connect European factories with Asiatic and African markets. An uninterrupted right-of-way from points in central Europe to populous Indian cities must necessarily pass through the valleys A Anatolia. Crossing thence the Taurus Mountains its natural passage is indicated as the Mesopotamian lowland and the shores of the Indian Ocean. Similarly land connection between Europe and Africa can be obtained only by passage through Asia Minor, Syria and Palestine. The occurrence of fuel within an area of such significance from the

Jan 6, 1916

In Table 47, tonnages shown before 1869 are estimated. After that time they are partly estimated from the total tonnage handled by the Allegheny Valley Railroad from four counties, of which this was one. Several reports to state authorities give a few figures, all probably very low, as is shown by the return in 1880 to the Secretary of Internal Affairs. [ ]

Jan 1, 1942

By E. Northcott, I. M. LeBaron

Before describing the electrostatic processing of feldspar, it might be well to review some of the basic definitions and terminology of feldspars. The feldspar minerals constitute a group of alumino-silicates of potassium, sodium, and calcium. Barium feldspar sometimes occurs naturally but is very rare. Hardness varies between 6 and 6.5 and specific gravity between 2.5 and 2.8. Color is generally white or pale shades of red, yellow, or green. The approximate chemical composition of the principal feldspars is given in Table I. The albite (sodium aluminum silicate) and an-

Jan 1, 1959

By V. F. Marsters

THE main producing oilfields in Peru are located in the department of Piura and province of Thumbes, adjoining Ecuador on the south and west. In the department of Puno, a small field known as the Pirin or Hauncané Area was exploited some years ago by Fred Brown and associates and considerable production obtained. As. shown by the statistical table of production, this area reached its maximum production about 1909; since 1915, operations have been suspended. During the past year, however, the Peruvian Corpn. has acquired some interests in this section. It is reported to have made a few shallow tests with the hope of obtaining sufficient production to supply fuel for its railway lines, which operate between Mollendo on the coast and Puno and Cuzco in the interior. Only partial success has accompanied these efforts; nevertheless, exploitation is being continued. The petroleum of this region contains a paraffin base with small amounts of asphalt. While the gasoline content is small, the kerosene content runs as high as 30 per cent., with the fuel element varying from 50 to 72 per cent. While it is known that the structural conditions of the Huancané area are somewhat complicated, it is believed that exploitation based on a careful interpretation of the geology of the region will eventually yield commercial production of at least modest proportions. In the main fields in Piura and Tumbes, drilling operations were somewhat more active during the first half of the year, than in 1922. The latter half of the year witnessed curtailment, owing to the abnormal situation in the petroleum industry at that time. For the same reason, no attempt was made to obtain the maximum production from existing .wells. Production was pinched down and exportation of crude was correspondingly reduced during the latter half of 1923. Nevertheless, the total production of the Peruvian fields is considerably in excess of that for 1922, as is also the production of the Negritos area alone.

Jan 3, 1924

V. R. GARFIAS,* Palo Alto, Cal. (written discussion?).-Regarding the statement of Mr. Ordoñez, on page 1007, concerning the synclinal curving of sedimentary beds caused by the extrusion of volcanic necks, that "this phenomenon might occur, but it is not fully proved in our fields," I beg to reply that the funnel and anticlinal-ring structure is actually associated with igneous intrusions in the Mexican oil fields, as we were able to ascertain by plotting an underground contour map and making a structural model of the oil-bearing beds of the Ebano field. E. DE GOLFER, New York, N. Y. (written discussion?).-The paper under discussion is not only of interest in connection with its subject but it is a contribution of considerable importance to our knowledge of the possible effect of igneous rocks upon the accumulation of petroleum in the Mexican fields.

Jan 10, 1918

By Michael F. Dunn, Francis S. Kendorski

The fall of rock from strip coal mine highwalls continues to be the largest single source of fatal accidents, so methods to improve highwall stability through improved blasting practices were investigated in the field. This paper covers the results of a project to improve, using existing and proven technology, unstable highwall conditions through better blasting practices in Appalachian strip coal mines. Better borehole blasting agent distribution and optimization of burden, spacing, and delay periods allowing satisfactory breakage with minimal backbreak were the objectives. At a selected field site, geologic conditions were closely examined with regard to joint orientation and spacing, and resulting slope stability considerations. Utilizing surface blasting concepts of trying to achieve flexural failure of the rock mass both horizontally and longitudinally by appropriate relationships between burden, spacing, and hole length, as well as delay time sequence to achieve optimal confinement and breakage, successful results were achieved. A test series of eight blasts was completed and the resultant highwall monitored by repetitive photography. Actual blockfalls could be measured and the stability for each blast design thus quantified. The study of drilling and blasting economics along with equipment performance led to an economic model of blast parameters and the identification of blast design cost benefits. The work demonstrated that small strip mining companies are able to achieve a more stable highwall excavation utilizing presently available technology, equipment, and explosive products at improved operational cost and safety.

Jan 1, 1983

By W. A. J. M. Van Waterschoot Van Der Gracht

The commercial production of petroleum in Germany is confined to the North German plain, in the Hereynian foreland, and the intramontane Permian salt basin of Thuringia, south of the Hare Mountains. Petroleum is produced in the former only in connection with salt domes, upthrust through Tertiary and Mezozoic strata of great thickness. In the basin of Thuringia petroleum is found in a Permian dolomite underlying a salt formation. It is exclusively in the peripheric zone of a few of the salt plugs in the North German plains region that commercial oil has so far been developed, notably in the following fields, all in the general region northeast of the city of Hanover: (1) Hänigsen-Obershagen-Nienhagen, south of Celle; producing from horizons in the Upper Triassic, the Middle Jurassic and the Lower Cretaceous; (2) Oberg, south of Peine; producing from horizons in the Middle Jurassic and Lower Cretaceous; (3) Oelheim-Eddesse, north of Peine; producing from horizons in the Upper Triassic, Lower and Middle Jurassic; (4) Wietze, west of Celle, where the main producing horizon is in the Lower Cretaceous. In some of these oil fields production from surface seepages was mentioned as early as 1669 (Oberg). Commercial production of importance dates only from recent time.

Jan 1, 1932

By William J. Priestley

Much time has been devoted, by metallurgists, to the study of steel after solidification and remarkable strides have been made in the heat treatment of steel, but less knowledge is available of the thermophysical activity of the constituents of steel prior to solidification in the mold. It is known that certain elements added to steel produce marked changes in physical properties, also that other elements added to steel produce similar changes, but we have only meager knowledge as 'to. how these elements combine in steel under different conditions of solidification. It is not sufficient to know, from chemical analysis, that a certain element is present in steel. We should know how this element is in combination with the other elements and whether the combination is such as will give the greatest physical properties. Certain elements go into solid solution with the iron, while others segregate to the grain boundaries and combine with the impurities collected there. Until it is known where an alloy produces the most beneficial effect and a means is determined for controlling its physical location by altering solidification conditions, or otherwise, we will not obtain the maximum value from our alloys. When molten steel freezes, it forms a heterogeneous mass of various crystalline constituents; and as the transformation of steel from a liquid state to the solid crystallized state is a critical step, involving as great a transfer of heat as any other operation in the making of finished steel, a variation in the rate of this heat transfer will have much to do with the arrangement of the various constituents in the solid state. The object of this paper is to show some of the effects on steel caused by variations in the rate of cooling in the ingot mold, particularly as to ingotism, segregation, dendrites, and intergranular material.

Jan 1, 1924

By Rudolph Emmel

THE mines operated by the South American Development Co. are located in the Zaruma mining district of southwestern Ecuador. They are near the old mining town of Zaruma, which is the only important city in the canton of the same name. The district is situated in the upper end of a valley lying between two spurs of the Cordillera, one of which may be considered the Coast Range and the other an intermediate range. The mining camp proper, known as Portovelo, and the plant are 2.4 km. south of Zaruma, on the north bank of the Amarillo River, a tributary of the Tumbes River, which flows southwestward through Peru to the Pacific. Portovelo is difficult of access; it is reached from Guayaquil by means of river steamers and muleback. Embarking at Guayaquil, the route is down the Guayas River, across the Jambeli Canal, and up the Santa Rosa River to Santa Rosa, a distance of 177 km. From Santa Rosa, the road or trail follows the Santa Rosa River, then across the summit of the Coast Range into Portovelo, a distance of 74 km.-a two-day trip on muleback. The mining property of the South American Development Co. comprises 297 lode claims and 142 placer claims. The combined lode claims cover an area, roughly rectangular in shape, 9000 m. long from north to south by 4000 m. wide; the northern edge of the rectangle is about 3000 m. north of the central plaza of Zaruma. Mineral lands in Ecuador are held by virtue of an annual tax per claim paid to the central government, no surface rights being included.

Jan 1, 1925

The plans for the activities of the Petroleum Division for the coming year do not differ materially from those of the past several years. The fall meeting is scheduled for Oct. 12 and 13 and is to be held at Tulsa, Oklahoma. The Division, of course, will take part in the annual meeting of the Institute at New York. A fall meeting will also be held in California at approximately the same time as the meeting at Tulsa. A number of papers are to be presented at the two meetings simultaneously. The various committees are at work arranging the programs. The Division will continue to be active in its various fields of endeavor, such as stabilization, production reviews, and economics, but special stress is to be laid on the engineering and research fields. In the past the Division has served as a forum for open and frank discussion of problems confronting the engineers in the oil industry. It is hoped that it will continue to function in this capacity. Papers presenting original ideas and extending the boundaries of knowledge and understanding in the field of petroleum production will be welcomed. Members who have interesting information to contribute should not wait until called upon by one of the Committees, but should offer a paper at the earliest opportunity. The past year has seen a decided strengthening of the control over production, with prospects of even more rigid control in the future. It is essential that production programs under such control be carefully planned and it is highly desirable that petroleum engineers take an active part in the planning, to insure efficient production of oil and minimize the waste of this natural resource. At a time like this, when it is difficult to keep the production of oil within reasonable limits, it may seem unnecessary to improve the efficiency of production methods, but, as has been aptly said, the trouble is not that we have too great a reserve of oil but that we are producing tomorrow's oil today. Therefore it behooves those who are entrusted with the engineering and scientific phases of production to learn how to get the greatest yield economically possible from the present and future fields in order that we may enjoy the advantages of petroleum products for a long time to come.

Jan 1, 1934

By L. R. Grabill

The Bassick mine, located six miles east of Silver Cliff, Colorado, has, ever since its discovery, been noted for peculiar features. Some of these characteristics exist in one or two other mines, while some are entirely unique. Among these peculiarities I have selected the most noticeable for treatment in this paper: First. The methods of deposition of the ores, which is not, as in ordinary veins, in strata or layers parallel to the walls of the fissure. The ores are arranged in concentric layers upon detached and abraded fragments of the walls; each ore in a separate stratum, and always in the same place in the series. Second. The characteristics of the fissure or opening; its shape and dimensions; its contents, or the vein-filling; and its verticality. Third. The peculiar products of the mine. The most noticeable of these products is charcoal, which is occasionally, and at long intervals, found throughout the ore-body, and in the surrounding conglomerate, from the surface down to the present depth, which is something over eight hundred feet. The existence of charcoal here is, as far as I know, the only instance of its discovery in mines of metallic ores. Fourth. Besides the charcoal, there are other products, in themselves not peculiar, whose manner of arrangement and composition are unusual. The mine is situated near the centre of a small rounded hill of eruptive trachytic rock and feldspathic conglomerate. The diameter of the base of this hill varies from 700 to 1200 feet, and its height is 200 feet above the general level. A cliff or outcrop of fine conglomerate is exposed on the southwest side of the hill. On the northeast it joins by an upward slope the fine-grained, hardened feldspathic paste of Mount Tyndall, which rises 600 feet higher, and of which the elevation containing the Bassick mine thus forms an arm. On visiting the mine, one's attention, whether he is a scientist or not, is immediately attracted by the unusual method of arrangement of the ore. It is seen to be disposed in concentric layers around fragments of trachyte. These fragments, of which each one con-

Jan 1, 1883

By T. K. Prentice

ABSTRACTED AND REVIEWED BY E. W. DAVIS,* MEMBER A.I.M.E. THE January-February number of the Journal of the Chemical Metallurgical and Mining Society of South Africa is made up entirely of a discussion of Ball Wear in Cylindrical Mills. Following the principal paper by T. K. Prentice are several remarkably pertinent and carefully prepared discussions. Few persons in this country would be likely to see this publication, and since the information presented is new and of current interest, it seems desirable to abstract and review this publication for the benefit of the members of the A.I.M.E. The purpose of the investigation is stated in the first two paragraphs of Prentice's paper, as follows: Early in 1941, The Chamber of Mines Steel Products, Limited, initiated a series of tests under semi-working scale conditions to determine, if possible, those physical and chemical properties of a ball which make it resistant to wear when used in a cylindrical mill as a grinding medium, with the primary object of incorporating those beneficial qualities in the balls being produced at their works. This paper describes the tests carried out and discusses the results obtained. From these results it was possible to formulate a new theory relating to ball wear in cylindrical mills. This theory is presented in the second portion of this paper. PRACTICAL BALL-MILL TESTS IN A CYLINDRICAL MILL Part I of the paper begins with a discussion of the methods used for the manufacture of grinding balls in South Africa. The following paragraph is of particular interest. The cast steel ingots, 4 ¼ - in. square by 3 ft. 6 in. long, are re-heated in a gas-fired sloping stationary-hearth furnace and then rolled in a six-pass continuous mill into 2 5/8 in. round billets. Some of these billets are then removed and cut into suitable lengths for forging into 4 in., 3 ½ in., 3 in. or 2 ½ in. balls by means of three Drop and two Beché hammers, but the greater number, whilst still at about 1,000 ºC., pass directly into a set of scroll rolls which produce, in an ingenious manner, finished 3 in. balls direct from the 2 5/8 in. billets. Except in special cases, all balls are allowed to cool in the atmosphere and are not water quenched. Details of the Tests In order to enable the reader to evaluate properly the results and conclusions in the rest of the paper and in the discussions following the paper, most of the information presented by the author under this heading is quoted: ….. The testing unit was a nominal 30 in. diameter and 18 in. long centre discharge Denver Ball Mill. The ore pulp to the ball mill comprised a small portion of the normal feed to one of the fourteen City Deep 5 ft. 6 in. X 22 ft. tube mills, and the grinding media consisted of the balls under test plus other balls to give the desired load. The running time of the test-mill was divided into approximately equal periods of five days 13 ½ hours each. The usual procedure was to examine and make up the load

Jan 1, 1944

By Jonathan S. Jackson, Bruce P. Ream

Leach water management is one of the few areas in dump leaching subject to operator control. As such, it is of considerable importance. Theoretical considerations indicate that high leach solution application rates are inefficient in washing solubilized copper from dumps. The high rates cause unnecessary dilution of copper values, raising unit recovery costs. Use of excessive amounts of leach solution also cools dumps, resulting in reduced leaching rates. This paper reviews leach solution application methods and details the results of field tests run to determine the benefits and feasibility of low versus high application rate techniques of applying water to dump surfaces.

Jan 1, 1980

By Edward Jeffrey

THE use of coke in metallurgy, to any important degree, dates from the middle of the 18th century. Its utilization came most opportunely for European civilization. The forests of Europe, except in the most remote and inaccessible regions, had been largely fed, in the form of charcoal, into the smelting furnaces. For a hundred years-the middle of the 17th to the middle of the 18th century-there was a stationary condition of population corresponding to the exhaustion of European forests. This situation, which was particularly evident in Great Britain, was due to the fact that the forests had been depleted and the practical utilization of coke had not begun. The coking industry is essential for our metallurgical industries, which in turn are basal to healthy economic progress. But coke is of great importance, not only on its own account, but for its byproducts, which enter fundamentally into all the arts of peace and war. The dyestuff industry and the manufacture of explosives are intimately connected with one another, as was shown by the recent war. The subject of coking coal, therefore, is well worthy the serious attention both of practical industry and the scientific investigator. The most valuable coking coals, from the metallurgical standpoint, are derived from the coals of highest ranks. Coals, for example, that have a carbon ratio of from 70 to 80 per cent. yield the most valuable coke for the blast furnace. The difficulty of investigating these coals, however, is great, for they are rather friable and delicate and possess a high carbon content, which makes them difficult to manipulate. They present, on account of their high carbon content, a considerable degree of opacity when examined, in thin sections, under the microscope. The tenderness of structure and blackness of such high-grade coking coals as those of Connellsville and the Pocahontas region make them extremely difficult to investigate.

Jan 1, 1925