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WILLIAM H. KOBBÉ (communication to the Secretary*).-I have read with much interest the discussion of my paper by Arthur Knapp and I. N. Knapp published in the March Bulletin. These discussions apparently assume that my paper advances a. number of ideas that are not intended: 1. That the total sandbody or pay is to be removed. 2. That upon bringing this sand and oil to the surface 100 per cent., or perfect separation, can take place. 3. That this tremendous quantity of sand is then hauled away in wagons and distributed as road material. The paper raider discussion is not a theoretical treatment of the subject but is the result of actual experience in oil production under the conditions mentioned.. That wells that produce sand produce in ore oil, and the best operating methods to bring this about are fully treated. It is, of course, impossible to remove all the oil sand underlying a property, but the greater the amount removed the greater becomes the production of oil. As stated in my paper, the surface disposal of this large volume of sand is a problem and the only use to which it can be put is road surfacing; but I did not intend to convey the idea that all this sand was thus used. Only a very small quantity was required on the company's roads, and two wagons only were employed for this purpose. The remaining sand accumulated in the numerous "washes" and sumps. Although this sand contained sufficient oil to stain the hands, it was, surprisingly dry and could be easily shoveled. As stated in the paper, "the piles of sand are gradually freed of their oil content and a crust forms on their surface which will bear the weight of a man." I consider this a high degree of separation. A small amount of oil necessarily remains in the sand and is held there by capillarity. Otherwise it would be useless as a road binder, and, furthermore, to recover such oil special processes of treating are required. Arthur Knapp says, "of the total volume produced by pumping, not more than 4 or 5 per cent. can possibly be sand." I cannot agree with this statement as I have managed many properties where the wells were so operated that the amount of sand produced was five times this figure.

Jan 6, 1917

By Edward Adarns Richardson

As developed up to the end of the Great War, an airplane was essentially a mechanism of wood and fabric, joined and held together by metal fittings and fastening. The engine and accessories, wire for wheel spokes and other tension members, and the occasional use of metal for inter-plane struts and the shafts of surface controls required some metal, but essentially it was a wood and fabric structure. Attempts had been made to use metal for other purposes, such as struts in the drag-trussing of wing panels and for short interplane struts, and Junkers had produced an airplane of iron in 1915. By 1917 he was using steel tubes and duralumin sheets, securing noteworthy advantages aerodynamically and from the standpoint of weight and upkeep. He was a pioneer along lines in which progress is still being made. Principles of Airplane Construction The loaded weight of airplanes ranges from 500 lb. for the light plane of which we heard so much a short time ago, to about 40,000 Ib. The great majority of planes range from 2000 to 10,000 Ib. Of this weight from 15 to 30 per cent. is for the dividend-earning load. This percentage is so low that every per cent. saved on the rest of the weight increases the pay load from 3 to 6 per cent,. The economic value of every pound that can be saved in designing or constructing a plane is sufficiently great to warrant spending money on refined methods of structural analysis, materials of superior strength properties for a given weight, methods of manufacture which may make possible the use of refinements in structural design, and the like, to an extent unknown heretofore. The weight of the airplane, without fuel, oil and crew, and pay load, ranges from 50 to 65 per cent. of the total weight loaded for planes suitable for commercial use. It is doubtful if the structural weight will ever be brought down to as low as 40 per cent. for commercial planes. The airplane may be roughly divided into: (1) Power plant, which includes engines, radiators, cooling water, oil and fuel tanks, piping, propellers, engine-starting systems, pumps, super-

By George H. Cunningham, Allen C. Jephson

The plant for production of electrolytic zinc recently erected by the American Smelting and Rcfining Co. is situated along Nueces Bay, on the Gulf Coast, some 5 miles west by rail and highway from the city and port of Corpus Christi. A ship channel from the port now approaches to within 2 miles of the site. It is expected that this will be extended at some future date and so provide direct water shipment from the plant. In addition to Gulf shipping, an intercoastal waterway connects Corpus Christi with Houston and New Orleans. Factors leading to the establishment oi this plant in the area were: ample supplies of natural gas for the generation of electric power, advantageous shipping lanes, favorable market for acid, adequate supply of labor, and moderate climate. General Description The plant was erected primarily to assist with the production of high-grade zinc much needed for war purposes. Production started during October 1942. The purity of the slab-zinc output meets the American Society for Testing Materials' special high-grade spccifications. Other products of the plant are electrolytic cadmium and sulphuric acid. Residues containing lead, copper and silvcr are sent for treatment to the Company's smelter at El Paso, Texas. The design of the plant includes the use of Trail suspension roasting equipment, contact acid equipment, also batch leaching in mechanically agitated tanks, pressure filtering and washing of leach pulp, batch purification in mechanically agitated tanks followed by clarification in filter presses and cooling of purified solution by evaporation. Electrolysis is performed in cells using Tainton alloy anodes and aluminum cathodes. Cathode current density is 60 amp. per square foot. Except for the portion returned to the leaching division, the cell solution is continuously flowing in closed circuit through the cells to cooling towers, which hold cell temperatures within desired limits. Direct current for electrolysis, is supplied by generators driven by steam turbines. The cathode zinc is melted in a gas-fired furnace and cast in the usual way into slabs for shipment. The plant divides into five major divisions: Concentrates Storage, Roasting and Acid, Leaching, Electrolysis, Melting and Casting. No attempt is made to give many tabulated data in this paper; it is mainly a general description of the divisions and methods employed for operation. A plan is shown in Fig. I and a general flowsheet in Fig. 3. Concentrates Storage The original plan for inward shipments was to receive zinc concentrates by steamer at the port of Corpus Christi, there to unload into open railroad cars and move into the plant by rail. Up to the present, however, concentrates have been received mainly in box cars from mines in Mexico.

Jan 1, 1944

By Thomas T. Read

Readjustment of the industrial world to a peace basis after more than 4 years of war will involve many fundamental and far-reaching changes that cannot as yet be clearly foreseen or definitely provided for. Such problems may be subdivided, in the vocabulary of war, into those involving material and those centering about personnel. Of the two, the latter group is the more difficult and obscure, as the factors involved are less clearly understood and the methods to be followed are not yet tested and standardized. When it is said that the market is weak, stocks large, and demand light, every business man understands clearly what is meant and what course he should adopt to adjust himself, so far as possible, to such conditions. But when it is said that the rapid spread of Bolshevism in Europe is a danger to industrial organization in this country, it is difficult to have any assured sense that all that the statement may mean is clearly understood or that the means to be followed to meet such a situation are definitely known. Since Bolshevism is primarily a mental phenomenon and since the rupture it brings about in industrial organization should be prevented, if possible, it is my purpose to restrict this discussion of the activities of the Committee on Industrial Organization to some of its mental aspects, as the chairmen of the sub-committees, from their special knowledge of their own fields, can best set forth recent progress in the lines with which they are especially concerned. The first requisites of success in industrial organization, as in the biological organism of which it is the social counterpart, are unity of purpose and coordinated activity. Typical good and bad examples of this' are the relative parts that the United States and Russia have played in the great war. These two factors are primarily mental, and it is not difficult to view the mental aspects of all problems of industrial organization as the most important ones. Unless we can attain unity of purpose and coordinated activity in industry, the provision of comfortable homes at reasonable rent, the assurance of steady work at good wages, the elimination of industrial accidents, and provision against want in old age or in case of disability will have brought us no nearer to our real goal.

Jan 1, 1919

By M. C. Van Camp, J. D. Miller

Preliminary results are reported regarding the design and development of a pilot scale air sparged hydrocyclone for cleaning fine coal 590 pm (- 28 mesh) containing 24% ash and 1.6% sulfur. The principle of separation is the flotation of hydrophobic coal particles in the centnjugal field generated by the fluid flow in the air sparged hydrocyclone as discussed in another publication. This 152-mm (6-in.) hydrocyclone has a nominal capacity of 0.9 t/h (1 tph) and experimental results suggest that separations vastly superior to a water-only cyclone are possible. In addition the separation efficiency is as good, if not better, than that achieved with conventional flotation cells. For example, typical results indicate that 75% clean coal can be recovered at 15% ash leaving a tailing product of almost 50% ash. These experimental results coupled with the high capacity of the air sparged hydrocyclone (imagine a retention time for flotation of only two seconds compared to two minutes for conventional flotation) may represent a significant breakthrough, not only in coal preparation technology, but in the flotation of fine particles in general.

Jan 1, 1983

By D. H. Yardley

GEOCHEMICAL investigation of trace elements in surface materials was begun near Ely, Minn., in 1953 along the basal contact of Duluth gabbro with Giants Range granite (Fig. 1). This article presents data on the distribution of copper and nickel in till and in stream sediments in the area and proposes an explanation for the types of distribution found. The Duluth gabbro, one of the world's largest basic intrusives, intrudes rocks which range in age from Keewatin to middle Keweenawan. Within the test area the gabbro is in contact with granite except for short sections where it is in contact with remnants of iron formation. Sulfide mineralization occurs within the gabbro, near and parallel to the basal contact for a distance of several miles. Schwartz and Davidson1 have described the geologic setting of the mineralization.

Jan 7, 1958

By H. M. Crankshaw

The early methods of mining anthracite in the steep pitching Mammoth bed consisted in driving breasts up the pitch from the gangways and airways driven in the bed along the strike (Plate 2, Fig. 1). Breasts are simply rooms driven up the pitch the full thickness of the bed (Plate 2, Fig. 2), having a width of from 18 to 30 ft., and a manway or traveling way on one or both sides. (For detail of breast method see Whildin, Trans., vol. 50, p. 704). Many difficulties were encountered, and the maintenance cost of the timbered gangways was so great as to be practically prohibitive. To reduce this expense, the gangways were driven in the thin Skidmore bed underlying the Mammoth, and the coal mined through rock holes. (Plate 2, Fig. 2, A.) It was found that after the breasts were driven up 80 to 100 ft., the coal almost invariably rushed or "ran away," making good ventilation almost impossible and the extraction of coal from the upper portion of the lift very difficult. The economic length of a lift is from 200 to 250 ft., and the percentage of extraction by the old method above mentioned was often under 50 per cent., while the coal recovered was so badly broken up as to reduce materially the percentage of large sizes. Principles of Present Mining Methods The present methods designed for the recovery of a maximum percentage of coal and a maximum yield of the prepared sizes depends largely on the following principles: First.—Formerly the practice in mining bituminous coal was to space rooms so that as much coal as possible could be extracted in first mining (Plate 3). The small pillars were often lost, and an improvement in total extraction was found in the system of driving narrow rooms with wide pillars, with a much larger final recovery (Plate 4). Second.—The early method of ventilation was to maintain a single

Jan 1, 1917

By Carlton D. Hulin

The usual concurrence in time and space of intrusive igneous activity, favorable structural disturbance and mineralization, which is so manifest in the mineralized district necessarily indicates a close interrelationship between these events. Evaluation of available evidence leads to the recognition that an appreciable time interval exists between the emplacement of the igneous intrusive and the formation of associated ore deposits. During this interval known portions of the intrusive are completely solidified, highly differentiated magma facies are injected as dikes, and important faulting occurs, which may fracture and shatter the solidified intrusive body. The highly differentiated dike types could only have originated in some deep portion of an underlying plutonic body that had reached an advanced stage of magmatic differentiation. Appearing after these dikes, the mineralizing solutions may likewise be presumed to have originated at great depth. Certainly no source for these solutions can be found in near-by portions of the intrusive igneous body. The association of igneous intrusives and clustering ore deposits must be recognized as resulting from structural control. The emplacemerit and the subsequent solidification and cooling of the intrusive set in operation forces that are responsible for the favorable structural disturbances that control the mineralized district. The emplacement of the body of fluid magma weakens the crustal rocks to the extent that failure due to strains originally present in the rock body may occur. Faulting of any type and of any magnitude may be the result. Subsequently, owing to the change of state from fluid magma to crystalline granitic rock, volume decreases approximating 10 Per cent may Occur, with resultant shrinkage and collapse within the rock body. Following solidification, thermal contraction, induced by cooling of the rock body, causes a further volume reduction of 6 per cent. This thermal contraction, extending over a lengthy period of time, results in a succession of minor fault movements. These small fault movements, occurring progressively throughout the period of mineralization, are responsible for maintaining the permeability of the rock body, without which access of the mineralizing solutions and the formation of the ore deposits of the mineralized district would be impossible. Introduction A proper understanding of the causes that have localized our mineralized districts should be of considerable value to geologist and engineer alike. under current conditions the known ore reserves of productive mining camps are being rapidly depleted. Although ore of the future will be derived in part from deposits now known and from Ore bodies that are still to be discovered within the limits of productive mining districts, in part at least it must come from mineralized districts whose existence or importance yet remain to be recognized. The mining geologist is thus faced with two problems of paramount importance: (I) the location of new ore bodies within known mineralized areas and (2) the location of new mineralized districts within whose confines, previously unknown, valuable Ore deposits may occur. Any contribution to our knowledge concerning the causes for the localization of mineralized districts

Jan 1, 1949

By Carlton D. Hulin

The usual concurrence in time and space of intrusive igneous activity, favorable structural disturbance and mineralization, which is so manifest in the mineralized district necessarily indicates a close interrelationship between these events. Evaluation of available evidence leads to the recognition that an appreciable time interval exists between the emplacement of the igneous intrusive and the formation of associated ore deposits. During this interval known portions of the intrusive are completely solidified, highly differentiated magma facies are injected as dikes, and important faulting occurs, which may fracture and shatter the solidified intrusive body. The highly differentiated dike types could only have originated in some deep portion of an underlying plutonic body that had reached an advanced stage of magmatic differentiation. Appearing after these dikes, the mineralizing solutions may likewise be presumed to have originated at great depth. Certainly no source for these solutions can be found in near-by portions of the intrusive igneous body. The association of igneous intrusives and clustering ore deposits must be recognized as resulting from structural control. The emplacemerit and the subsequent solidification and cooling of the intrusive set in operation forces that are responsible for the favorable structural disturbances that control the mineralized district. The emplacement of the body of fluid magma weakens the crustal rocks to the extent that failure due to strains originally present in the rock body may occur. Faulting of any type and of any magnitude may be the result. Subsequently, owing to the change of state from fluid magma to crystalline granitic rock, volume decreases approximating 10 Per cent may Occur, with resultant shrinkage and collapse within the rock body. Following solidification, thermal contraction, induced by cooling of the rock body, causes a further volume reduction of 6 per cent. This thermal contraction, extending over a lengthy period of time, results in a succession of minor fault movements. These small fault movements, occurring progressively throughout the period of mineralization, are responsible for maintaining the permeability of the rock body, without which access of the mineralizing solutions and the formation of the ore deposits of the mineralized district would be impossible. Introduction A proper understanding of the causes that have localized our mineralized districts should be of considerable value to geologist and engineer alike. under current conditions the known ore reserves of productive mining camps are being rapidly depleted. Although ore of the future will be derived in part from deposits now known and from Ore bodies that are still to be discovered within the limits of productive mining districts, in part at least it must come from mineralized districts whose existence or importance yet remain to be recognized. The mining geologist is thus faced with two problems of paramount importance: (I) the location of new ore bodies within known mineralized areas and (2) the location of new mineralized districts within whose confines, previously unknown, valuable Ore deposits may occur. Any contribution to our knowledge concerning the causes for the localization of mineralized districts

Jan 1, 1949

By B. Barlin

Introduction The development of metallurgical practice at lambia Broken Hill is directly related to the change in mineralization of the deposits as mining progressed from the open pits to underground. The ore consists of a mixture of lead and zinc sulphide minerals, together with abundant silicates, carbonates and other oxidized minerals of these metals. The irregularity that characterizes the shape of the orebodies applies equally to their mineral content, which makes ore reserve calculations and the maintenance of a balanced feed to the metallurgical plants, problems of some magnitude. History The Rhodesia Broken Hill Development ,Company was formed in 1904 after an Australian prospector, T. G. Davey, discovered the outcrops in 1902. In the early years zinc ores were calcined for shipment but this proved uneconomic. Cerussite outcrops were then smelted directly in blast furnaces for the production of lead until 1929 when ore above the water level was exhausted.

Jan 1, 1970

Research and Development, once considered a luxury item only for well-heeled companies, has in the last two decades come into its own as a vital contributor to the fortunes of electronic, automotive, chemical and aerospace firms. In terms of money and talent poured into research, the mining industry is still far behind those industries. Although the U.S. Bureau of Mines, plus various mining and manufacturing firms and universities have made notable contributions to mining technology, the historical pattern of mining R&D shows a heavy reliance on the results of research in other industries. It is difficult to tell whether this pattern will change significantly in the future, but there is evidence of a growing awareness by mining officials that greater R&D efforts are going to be required not only to meet the nebulous demands of tomorrow's world but to meet the ever-present, mounting pressures being generated by "intra-metals" and "inter-materials" competition.

Jan 1, 1968

National Minerals Advisory Council A meeting of the National Minerals Advisory Council on August 3rd in Washington, D. C., indicated the vitally important part that the mining industry is to play in the mobilization program. Director James Boyd of the Bureau of Mines told the Council that the Department of the Interior would review the recommendations of all the Council's commodity committees with regard for mobilization planning in the light of the changed international picture. The Council was requested to reactivate its commodity committees and have them gather all available data on supplies, their sources and availability and present and potential production of the minerals and metals represented on each committee. Data on labor, machinery, transportation, automotive and stationary equipment, power, fuel, lumber, water supply are a few of the important items called for in the reports, which are to be presented at a meeting of the Council on September 1 at Salt Lake City. The material in the reports will become the basis for discussing metal and mineral requirements at that time. Discussion at the meeting bared several $64 questions, probably the most important of which are the following: 1. Which of the war-essential metals and minerals and in what quantities can we reasonably expect to get them from abroad under threat of submarines? 2. How are we going to meet the manpower problem posed by (a) migration of labor from mining to manufacturing since the end of World War II and (b) the draft and the calling up of reservists? Opinion was expressed by industry spokesman at the meeting that the function of complying with mobilization requirements be left to those in the industry itself; that is, those having the "know how." This view contended that any administrating governmental agency should be kept as small and streamlined as possible. There was general sentiment against the reactivation of the wartime Premium Price Plan or other bonus plans as a stimulus to production. The thought was emphasized that what was needed was a change in the basic conditions which have fostered the decline in domestic mining activity in the postwar years. One such condition, long overdue for correction, is the tax structure as it applies to mining enterprises. Many quarters both in industry and in government favor tax relief along the lines suggested in the six tax recommendations by the Council to the Secretary of the Interior last December. The Council adopted a resolution expressing a feeling that the following tax recommendations are still feasible and desirable and will accomplish as much toward increasing exploration for new deposits (thereby subsequently increasing production) as will government loans for exploration: (1) Losses from unprofitable ventures should be allowed corporations, partnerships, or individuals as ordinary deduction against current income. (2) Development costs after discovery should be recognized as operating expenses. (3) Allowance for depletion should be made to the stockholder as well as to the corporation. (4) Income should not be taxed without full allowance for losses of loss years. (5) Adequate allowances for percentage depletion should be made. A discussion of the manpower problem led to the Council's acceptance of a resolution advising that "military authorities should proceed with caution in depriving the mining and metallurgical industry of its manpower." The resolution strongly urged that no personnel "directly engaged in exploration, development, production or supervision (of strategic and critical materials) should be drafted for the armed forces, at least until the anticipated demands upon these producers are clarified." Stockpiles The Munitions Board's "Stockpile Report to the Congress" of July 23, 1950 revealed: (1) The total estimated value of the stockpile objective is $4,051,714,510 at the close of fiscal year 1950. (2) The total value of the stockpile on hand, at the close of fiscal 1950 was $1,556,154,352 or 38.4 pct of the total stockpile objective. An additional $494,948,060 was on order, making a total of 50.6 pct on hand plus the amount on order. (3) Materials obtained for the stockpile by the ECA from January to June 1950 amounted to $13,112,085, while development projects by ECA during this period involved the expenditure of $9,322,000, mainly with counterpart funds. Shortly after the start of the Korean conflict it was felt that Congress ould appropriate greatly increased sums for the purchase of materials for the stockpile. This stimulus to the program may increase the dollar earnings of those European nations that are present or potential contractors in our stockpiling program. Such a development would mean that these nations could add to their gold reserves, thereby stabilizing their respective economies and hastening recovery. This seems to be the picture for the next six months anyway. The "bug" appears when it is realized that the increased threat of total world war actually may retard recovery in Europe as nations on the continent may feel inclined to devote more of their resources to defense programs. Industries Essential to Defense The Department of Commerce in response to a request by the Department of Defense issued on August 3, 1950 a "Tentative List of Essential Activities" as a "guide for calling up for active duty members of the civilian components of the Armed Forces." The list includes the following: Primary Metal Industries. Included herein are establishments engaged in the smelting and refining of ferrous and nonferrous metals from ore, pig, or scrap. Metal Mining. This category includes establishments primarily engaged in mining, developing mines or exploring for metallic minerals (ores). This group includes all ore dressing and beneficiating operations. Anthracite Mining, Bituminous Coal and Lignite Mining, Crude Petroleum and Natural Gas Extraction, Mining and Quarrying of Nonmetallic Minerals, Except Fuels. Challenge to the Mining Industry The source of our country's great strength lies in its capacity to produce. In times of stress such things as national morale and manpower are all-important but without a capable industrial machine we would be helpless. That machine must be fed with minerals and metals in order to generate and maintain momentum sufficient to insure success. Consequences of the lack of adequate supplies of essential metals and minerals to increase and sustain our industrial power are not pleasant to contemplate. It is absolutely imperative that we put forth Herculean effort to guarantee ample supplies of such essential materials as copper, lead, zinc, manganese, antimony, mercury, tungsten, tin, chromite, nickel, cobalt, iron ore and rubber. The mining industry faces a challenge more serious than ever existed before in the history of our country. The industry must be equal to the task.

Jan 9, 1950

By N. Albon, J. F. Miller, R. W. Coutant

The deposition of nickel from nickel carbonyl onto amorphous substrates has been studied, with attention being paid to the specific effects of the physical and chemical nature of the substrate and to the effect of oxygen on the crystal morphology. With substrates having microscratches or etch lines, nu-cleation was observed to occur preferentially at these surface features. Flame polishing of the substrate surfaces was found to remove any regularity in preferred nucleation sites. Nucleation was observed to occur less readily on substrates having relatively low surface energies, e.g., Teflon and carbon, than on materials having relatively high surface energies such as fused silica. At low oxygen concentrations [Ni(CO)4/O2 > 54 x 1031, apparently pure and well-formed nickel crystals were observed to nucleate and grow irrespective of the presence of oxygen. At higher concentrations of oxygen, a secondary growth process, dependent upon oxygen concentration and resulting in a gradual change in crystal morphology, was observed. It is concluded that the influence of oxygen on the nucleation and growth of nickel is determined by the relative kinetics of the various possible reactions, and that under the experimental conditions employed the 0-Ni interaction occurs at some nucleation or prenuclea-tion stage. THE purpose of the research on crystal nucleation in chemical vapor deposition as described in this paper has been twofold: 1) to examine some effects arising from the use of amorphous substrates, and 2) to study the specific effects of oxygen on the nucleation and growth of nickel in a nickel carbonyl-carbon monoxide system. The nickel-nickel carbonyl system was chosen for study for several reasons: 1) nickel films are of potential interest in electronic technology, and 2) the deposition can be carried out at moderate temperatures, thus making possible detailed study of the processes occurring and the use of a variety of substrate materials (including some which melt at relatively low temperatures). Fairly well-characterized chemical kinetics and a broad background of information are available on the py-rolysis reactions and on the mechanisms of Ni-O interactions. NUCLEATION AND GROWTH THEORY The theoretical background for the analysis of nucleation and growth by vapor deposition for a one-component system (physical vapor deposition) and the problems encountered therein have been reviewed by Hirth and pound.' More recently Mande12 has indicated the difficulties of applying such theory to chemical systems. One of the major problems involved is the possible multiplicity of chemical reactions and deposition routes. For example, those reactions which are probably of significance in a discussion of the pyrolytic deposition of nickel from nickel carbonyl under the conditions of the present experimental work are illustrated in Fig. 1. As is true with most cases of chemical deposition, many of the quantitative data necessary for a complete analysis of the system are either not available or not directly measurable. However, with the present system, sufficient data are available for a discussion of nucleation and growth on a qualitative basis. Classically, the rate of nucleation of a monatomic species being deposited from a vapor phase is given by

Jan 1, 1965

By Ernest A. Hersam

The rate of output of a rock crusher is based upon a certain space relation, the calculation requiring that the size and position of the jaws, the principle of motion, and the speed of the machine be known. The result is a calculated maximum output. The purpose of this paper is to develop a method of calculating this maximum output, to judge the general applicability or utility of such a calculation, and, so far as possible, to lecord calculated values as a basis for the comparison of actual results, or for estimating the capacity of a new crusher or of a standard crusher working under new conditions. A method for calculating the capacity of crushing rolls, which has been in common use for a long time, is well presented by R. H. Richards.' The output is conceived as a ribbon of rock, of which the breadth, thickness and length are governed respectively by the width of the rolls, the space between them, and their peripheral velocity. The weight of the rock thus crushed in a given time can be calculated from its specific gravity, after applying a factor representing the percentage of voids in the hypothetical ribbon. The calculation of crusher capacity is made in a somewhat similar manner. While the action of rolls is simple, with few irregularities in operating conditions, in rock crushers the material advances intermittently, usually under the force of gravity alone, and is subjected to a variety of variable conditions. The effect of these variable influences upon the calculation of capacity is now to be shown. In this paper, capacity will be discussed quite apart from any consideration of mechanical efficiency; that is, results will be stated not in terms of output per horsepower, but of output for a given machine when operated at a known speed, constructed and adjusted to receive material of a known size, and to yield a product having a definite maximum coarseness.

Jan 1, 1923

By Ernest A. Hersam

The rate of output of a rock crusher is based upon a certain space relation, the calculation requiring that the size and position of the jaws, the principle of motion, and the speed of the machine be known. The result is a calculated maximum output. The purpose of this paper is to develop a method of calculating this maximum output, to judge the general applicability or utility of such a calculation, and, so far as possible, to lecord calculated values as a basis for the comparison of actual results, or for estimating the capacity of a new crusher or of a standard crusher working under new conditions. A method for calculating the capacity of crushing rolls, which has been in common use for a long time, is well presented by R. H. Richards.' The output is conceived as a ribbon of rock, of which the breadth, thickness and length are governed respectively by the width of the rolls, the space between them, and their peripheral velocity. The weight of the rock thus crushed in a given time can be calculated from its specific gravity, after applying a factor representing the percentage of voids in the hypothetical ribbon. The calculation of crusher capacity is made in a somewhat similar manner. While the action of rolls is simple, with few irregularities in operating conditions, in rock crushers the material advances intermittently, usually under the force of gravity alone, and is subjected to a variety of variable conditions. The effect of these variable influences upon the calculation of capacity is now to be shown. In this paper, capacity will be discussed quite apart from any consideration of mechanical efficiency; that is, results will be stated not in terms of output per horsepower, but of output for a given machine when operated at a known speed, constructed and adjusted to receive material of a known size, and to yield a product having a definite maximum coarseness.

Jan 1, 1923

By Richard L. Gordon

Minerals long have been important commodities in international trade. As an inevitable result, the governments of the world have employed a wide variety of programs that affect the flow of trade. Roughly speaking, we may distinguish between the desire of more developed countries (MDCs) like the United States, western Europe, and Japan to control imports of minerals and the concern of less developed countries (LDCs), like India, about exploiting and exporting their minerals. The terminology used to describe different countries and the classification of specific countries into groups is unsettled and often changing. The poorest countries have been characterized as backward, undeveloped, underdeveloped, and developing. The problem seems to be in selecting a term that is both accurate and polite. Less developed seems, for reasons outlined by Hagen [pp. 51-57], the most convenient term. The borderline between an LDC and an MDC is always open to dispute. Objective measures are difficult to develop because of deficiencies in basic data, and enormous conceptual problems arise in making valid comparisons from even good data [see Hagen, pp. 7-28]. Thus, policies of the MDCs can be evaluated chiefly by using a few basic arguments for protectionist attitudes towards international trade. In dealing with the LDCs, a more far-ranging evaluation that covers general economic policy goals, the role of foreign investment, and the indirect effects of trade is required. This duality breaks down when trying to deal with the depressed areas in an MDC; here the issues are more akin to those associated with problems in an LDC. Similarly, variants of arguments used in LDCs appear in debates about foreign investments in MDCs. The whole discussion of minerals in LDCs, moreover, has obvious implications for MDCs like Canada and Australia. They, too, must face problems about the best utilization of their resources. THE RESTRICTION OF MINERAL TRADE BY DEVELOPED COUNTRIES[a] At least to some extent, the world's leading industrial nations have intervened to control the inflow of minerals. Such regulation is particularly pronounced for energy. Both the United States and western Europe employ

Jan 1, 1976

By S. J. Hruska, G. M. Pound

The critical supersaturations for appreciable nucleation rate of cadmium crystals on copper and glass substrates at 186°Kwere measured as a junction of thermal-beam energy over a range of source temperatures between 616" and 839OK. There was no effect of source temperature on critical super saturation. This implies that the adsmbate prior to nucleation is in thermal equilibrium with the substrate. THE deposition of metallic vapors on solid substrates has been found to exhibit a critical behavior in that the rate of formation of deposit increases markedly when the intensity of the vapor source is increased slightly.* Evidence of the ability of sub- where Je is the flux which would arrive if the substrate were equilibrated with bulk condensate at the adsorbate temperature. The following work was undertaken to test this hypothesis. A) Energy Exchange Between Metallic Vapor and Substrates. When a freely translating atom collides with a stationary solid body its energy and momentum undergo changes which determine whether the atom is reflected or adsorbed. An atom is considered to be reflected if it returns to a freely translating state after remaining under the influence of the body for only a time comparable to the period of oscillation of atoms on the surface. An atom which remains for a longer time is said to be in an adsorbed state. The parameter which describes the energy transfer occurring at the interface is the thermal-accommodation coefficient which may be defined in terms of energy as Ei = average energy of impingent atoms, Eeq = average energy of an emergent atom which has equilibrated with the substrate, and Eem = average energy of an emergent atom. If a temperature is assigned to each of these energies, we have at as defined by Knudsen.2 Since this allows no distinction between reflected and evaporated atoms, a more specific definition is introduced for the present purposes, namely 71 = probability that an impingent atom is transferred to an adsorbed state, aj = thermal-accommodation coefficient for reflected atoms, and aTc = thermal-accommodation coefficient for adsorbed atoms. During a time t,, the mean stay time, prior to evaporation the adsorbed atom (adatom) will interact with the substrate and this will have the net effect of transferring the adatom towards a state of

Jan 1, 1964

By N. F. Schulz, H. A. Lex, J. D. Zetterstrom

A green ball of iron ore faces many perils from the time it is formed until it finally emerges from the pelletizing furnace as a hardened pellet. For instance, if the rate of heat transfer into a ball is sufficient to produce vapor from either the free or combined water more rapidly than it can escape at a tolerable pressure, the ball may split, spall, or even explode, a failure commonly known as decrepitation. To avoid such failures, one must either limit the rate of heat transfer during the drying and preheating stages, at the expense of production rates, or improve the decrepitation resistance of the green balls. The latter remedy may often be accomplished through changes in ore preparation, balling procedures, or the judicious use of binders or other additives. INTRODUCTION Pelletization has become established as an especially desirable method for the agglomeration of fine taconite concentrates and it promises to be equally satisfactory for improving the physical structures of certain natural ores. A high-quality pelletized iron ore consists of uniformly sized spheres, usually about 1/2-in. diam, which are strong enough to resist abrasion and breakage during handling and which reduce well without disintegration in the blast furnace. The unfired agglomerates, "green balls", are subject to several destructive effects that must be avoided or minimized if a high-quality product is to be obtained by pelletization. Among these are abrasion and impact deformation or breakage during handling of the wet green balls, deformation and breakage by compressive forces in the bed of ore in the pel-letizing furnace, decrepitation during drying and preheating, wind erosion, and radial cracking at firing temperatures. Moisture condensation from the warm saturated gases downstream from the drying zone on wet, cool balls may cause bed collapse if it becomes excessive. Decrepitation is defined as the sudden disintegration of green balls, usually with an audible pop, that occurs when they are heated too rapidly during the drying or preheating stages of the pelletization process. The extent of ball disintegration may vary from merely splitting off a small fragment to almost total disintegration into the original ore particles making up the ball. Such ball destruction results in a decreased yield of pellets, and the fragments, which also tend to interfere by obstructing the gas flow through the bed, must eventually be screened from the fired product and recycled. The closely related type of ball failure that sometimes occurs during the high temperature firing stage, resulting in radial cracks without fragmentation, was not considered to be decrepitation for the purpose of this investigation. Failure by decrepitation is not usually a serious problem in the pelletization of taconite concentrates. The problem is significant, however, in the pelletization of some natural ores, especially those containing hydrous iron oxides. In some instances, economicd production rates cannot be maintained if the drying and preheating rates are slowed down enough to avoid decrepitation. OBJECTIVES This investigation was undertaken to: (1) Develop a practical laboratory means for quantitatively measuring the tendency for green balls to decrepitate in iron ore pelletizing furnaces, and (2) Investigate the causes and cures of ball decrepitation. MATERIALS Two iron ores were used in the work reported here: a taconite concentrate at 90% minus 325 mesh, containing 65.0% Fe, 8.4% SiO2, and no loss-on-ignition; and a crude oxidized ore at 54% minus 325 mesh, containing 59.1% Fe, 3.6% SiO2, 1.1% A12O3, and 9.5% loss-on-ignition. For a special test of effect of particle size distribution on decrepitation, two other

Jan 1, 1967

By A. W. Schillinger

Drilling was not entirely satisfactory in the search for native copper in the Osceola amygdaloid footwall, for oreshoots mined were more continuous than drilling indicated. The Geophysics Dept of Michigan Technological University developed a portable induced polarization drill hole probe with a 3-electrode configuration and a sampling radius of 5 ft ±. A 20 ma current of alternately reversed polarity is pulsed at 3.5 sec intervals and readings are taken every 2 ft. Potential is read during the "on" cycle for resistivity determinations. During the "off" cycle, after 10 ms delay, the 1P potential is sampled for 10 ms and recorded. Resistivity (ohm-ft) and "S" values (mv/v) are plotted on semi-log paper. A lithologic log is plotted based on resistivity and anomalous S values noted. The low resistivity amygdaloid contains sills of high resistivity basalt. Verified by core logs, contacts between amygdaloid and basalt could be picked to ± 0.5 ft from resistivity alone. Lithologic logs of long-steel holes, based on resistivity, then replaced sludge logging. An S value of 30 mv/v was established as the lower limit of diagnostic 1P effects in mineralized amygdaloid and 50 mv/v as a threshold value for ore. Of 914 footwall zones drilled, 315 were probed yielding 203 anomalies. Success increased from 34% for drilling to 72% for drilling and probing. As checked by mining, 46 probe results were 78% correct. Failures were due to the instrument not detecting copper or to the misinterpretation of an anomaly. No false anomalies were found. During the past ten years, the Calumet Div. of Calumet &Hecla, Inc has conducted extensive exploration and mining in the footwall of the Osceola amygdaloid lode in the native copper district in Michigan's Upper Peninsula. In an attempt to delineate more clearly the extent and nature of high-grade footwall copper mineralization, 876 diamond drill and long steel holes aggregating slightly more than 47,000 ft have thus far been drilled from the accessible hanging-wall workings in the Osceola No. 6, 13, 14 and 15 shafts. Early in this program it became obvious, through inspection of footwall workings in progress, that due to the erratic and bunchy occurrence of the native copper in the footwall zone, the exploration drilling was failing to outline completely the extent of the oreshoots. Early drilling re-

Jan 1, 1964

By George Kunz

(Butte Meeting, August, 1913.) THE manifold inconveniences resulting from the absence of a uniform standard of mass for determining the weight of precious stones have long been obvious. This lack has been keenly felt in commercial transactions, and those who have devoted time and research to the study of historic diamonds and precious stones have had frequent occasion to deplore the absence of such a standard in the past. In a paper read in Chicago in 1893, before the International Congress of Weights and Measures, held in connection with the World's Columbian Exposition, the writer suggested dividing the carat into 100 parts, and constituting a standard international carat of 200 mg. ; that is, 5 diamond carats or 20 pearl grains to a French gram, making 5,000 carats or 20,000 pearl grains to a kilogram. He also called attention to the fact that while this would depreciate the present diamond carat or pearl grain only about 2.5 per cent., it would abolish the troublesome discrepancies between the various carat-weights now in use, and could be easily explained and understood everywhere.1 The subject of the various diamond carats, their incongruity, and the resulting confusion as to the correct weights of historic gems when definite records of them are searched for, has been fully treated by me in an extensive study of this subject in The Book of the Pearl.2 To the earnest and unremitting efforts of C. E. Guillaume, Director of the Bureau Internationale des Poids et Mesures at Sèvres, is largely clue the eventual success of this eminently desirable reform, which lie has constantly urged both by articles on the subject and by addresses delivered in Paris before the International Committee for Weights and Measures.3

Jan 7, 1913