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Efficient energy utilization in the electrolytic zinc process, relative to other zinc processes, is one of the reasons for its wide adoption in recent years, says John D. Siddle, zinc plant superintendent at the Bunker Hill Co., Kellogg, Idaho. Designers and operators of electrolytic zinc plants have pioneered process improvements, new equipment, and operating techniques to conserve energy. As energy costs increase it the future and competitive pressure mounts against less-efficient producers, these energy-saving improvements will he regarded as necessary for economic survival. Plant designers and operators should not lose sight of the savings in operating costs possible through intelligent utilization of all available forms of energy.

Jan 11, 1977

By F. C. Schora, H. P. Meissner

Both a graphical and an analytical technique are presented for calculating stream compositions and temperatures in adiabatic staged systems in which solids travel countercurrently to a gas stream. Such a system might be a tower containing several plates, on each of which the descending solid is fluidized by the rising gas stream. Examples are presented in which chemical reactions occur, including the oxidation of SO, by a solid catalyst and the gaseous reduction of iron oxides. COUNTERCURRENT staged processes involving reactions between solid and gas streams are becoming more common. These operations are generally carried out in a series of beds of fluidized solids, with each bed or "plate" acting as a stage. Fig. 1 is a schematic diagram of such a series of stages located in a column, down through which a solids stream moves from stage to stage counter to a rising gas stream. Typical reactions carried out in such systems are the dehydration of aluminum trihydrate, the calcining of limestone, and the gaseous reduction of iron oxides. Calculation of the performance of these counter-current systems rapidly becomes more complex with increases in the number of stages and in the number of chemical reactions occurring. Calcula-tional procedures for isothermal operations of such systems have been described.4 Actual tower operations, however, are generally adiabatic, and in consequence far from isothermal. The object here is to present both graphical and analytical techniques applicable to such adiabatic towers operating continuously and in steady state. In this introductory discussion, the graphical techniques presented are of the McCabe-Thiele type, rather than of the Pon-chon type. In all the examples presented, it will be assumed that both thermal and chemical equilibrium are attained in each bed. The assumption that the gas and solid streams leaving each bed are at the same temperature as the bed is in accordance with the familiar behavior of actual fluidized solid systems. Chemical equilibrium, on the other hand, is not necessarily attained in any given stage between these two streams, even with deep beds, since reaction rates may be slow. In the last section of this paper, discussion is presented of methods suitable for use when chemical equilibrium is not attained. The adiabatic tower in Fig. 1 has "n" stages numbered from 1 to n, starting with the bottom stage as number 1. In analyzing this tower's performance, it is important to express gas flow rates in terms of a key component or element which remains completely within the gas stream throughout the tower. Similarly, solid flow is best expressed in terms of a key compound or element which remains within the solid phase throughout the tower. Thus, in burning limestone with a hot flue gas, the gas flow might be expressed as G, the pound mols of nitrogen flowing through the tower per unit time, while solid flow might be expressed as S, the pound atoms of calcium in all forms in the solid stream per unit of time. Defined in this way, both G and S are constant throughout the tower. The enthalpy of the gas and solid streams are now best expressed in terms of these key components. That is, the gas stream enthalpy H is expressed as Btu in the total gas per mol of the key component in the gas. Similarly, the solids stream enthalpy h is expressed as Btu in the total solid stream per pound mol (or pound atom) of the key component in this stream.

Jan 1, 1962

By Eckley B. Coxe

IN the anthracite coal regions of Pennsylvania the custom has been to sight either at an open light (generally a mine-lamp), or at the string of a plumb-bob. If the station was intended to he a permanent one, a spud, as it is called, that is, a nail resembling a horseshoe nail with a hole in the head, is driven into the timbers over the station, or, if there be no timber, a hole is drilled in the coal or rock roof, into which a wooden plug is driven, which serves to hold the spud. The first operation in making a survey is to lay out the stations, that is, to mark the place where the holes are to be drilled for the plugs or the points on the timbers where the spuds are to be driven in. This should be done before any instrumental work is begun, as much labor can generally be spared, and the use of very short sights can often be avoided, by carefully laying out the stations beforehand. When the stations were laid out, a plumb-bob was hung from the innermost spud, which I will call No. 1, the instrument was put in position at No. 2, by plumbing down and putting a centre-pin under the spud, and then setting up over the centre-pin, and another plumb-bob was suspended from No. 3. If great accuracy was not required, a mine-lamp was set up under the plumbbobs, at No. 1 and No. 3, and the engineer sighted at them. If great accuracy was required, a lamp or some white sbface was held by an assistant behind the strings of the plumb-bobs. To work with any speed by the latter method (i. e., the accurate one), it was necessary for the engineer to have three assistants on whom he could rely even when the chaining was done afterwards; viz. : one to hold the light behind the string at No. 1, one at No. 3, and an assistant at the instrument to hold the light while levelling, reading the in

By Richard Franchot

From an efficiency viewpoint, the greatest loss of energy to the blast furnace is in its failure to convert more than about a third of the coke carbon from carbon monoxide to carbon dioxide. This result has usually been ascribed to a necessity of a 2:1 excess of CO in order to reduce iron. It has, however, been proved that iron is completely reduced by equal volumes of carbon monoxide and carbon dioxide. Hence there is room for the hypothesis that vaporization, as cyanid, of accumulated alkalis is a serious primary factor limiting the ratio of ore to coke. Observed cyanid vapor concentrations and those measured by the variations of the nitrogen-oxygen ratio in the hearth gases form the basis for a quantitative explanation of the furnace action. As EVERYBODY knows, the blast furnace is a gas producer. As to the reason for this, people are not so well agreed. The significance of the fact is obvious, for the extent to which the fuel leaves the furnace as combustible gas measures poor economy in iron smelting; while good efficiency in this respect means poor gas. The furnace thus works at cross purposes. The present trend of the steel industry is toward. a primary use of the blast furnace as a gas producer with pig iron as a byproduct. Needless to say, this trend is away from improvement in iron making. The production of more and better iron in a given furnace consuming a given amount of coke would seem, at least, to involve a decrease in the relative proportion of the combustible gas. The possibility at the same time, however, of making more and better gas need not necessarily be excluded. (The more the furnace acts as gas producer, the bigger is the sulfur problem.) Whatever the object, it would seem desirable to have a, clear, comprehensive, mathematically exact estimate of why and how the blast furnace functions, to the large degree that it now does, as a gas producer. The literature does not give a definite answer to the question. That for which explanation is sought is the fact that only a minor part, usually not more than a third, of the coke carbon burned is oxidized to carbon dioxide; that the development in the furnace of the fuel energy is thus limited usually to little more than 50 per cent.; that it requires about twice as much fuel coke to make a ton of iron as is indicated by the rela-

Jan 7, 1925

By Ralph E. Hartline, Wilfred Tapper

The Strataflow process for locating water entry in producing, wells is now available. This method as now practiced utilizes the fact that fluids of different salinities have different electrical resistivities. By introducing into the well a fluid of a markedly different salinity than that of the fluid being produced, a pronounced resistivity change will occur at the point of entry. By running a Strataflow survey the points of major and minor water entry may be interpreted from changes in the resistivity of fluid in the hole. Strataflow results are obtained with the well operating under almost normal producing conditions, and are a logical primary step in any workover program, having as its purpose shutting off of the water. INTRODUCTION Water production is a serious problem in many producing oil wells. It certainly increases lifting costs and in some cases presents a disposal problem. It often aggravates corrosion problems and can even endanger oil production. With accurate information to guide an effective workover program, many marginal wells could be restored to Profitable Production. The shortcomings of previous meth- ods of water entry location were recognized. The Strataflow process is the result of several years of development and field testing directed toward overcoming these limitations. It represents the continued development of a process reported by Silverman and Brown. The earlier work established the basic soundness of fresh-to-salt water resistivity contrast in delineating zones of water entry, but its application was limited by the difficulty of maintaining static balance of the well during preparation for the test. A more serious deterrent to its use, however. was its unadaptability to existing well logging service equipment and field operating methods. STRATAFLOW PRINCIPLE The general principle of the new method involves, first, conditioning the well by displacing the fluid in the bore of the well adjacent to the zone to be tested by a conditioning fluid which is miscible with the formation fluid. This displacement is carried out without interruption of the well production. The conditioning fluid must have some measurable physical, chemical, nuclear, or electrical property which is distinctive from that of the formation fluid. As the well continues to produce. formation liquid entering the well bore dilutes the conditioning fluid so that zones of entry may be determined by making a log of the property undergoing change. This general principle may be applied to indicate zones of either water or oil entry by suitable selection of conditioning fluid and proper logging equipment. The Strataflow process, as it is currently practiced for water entry location, uses fresh water as the conditioning fluid and depends for its operation upon the marked difference of electrical resistivity between this fresh water and the salty water produced by the formations. If possible. any necessary modifications of the well equipment are made a week or so before the test. The well is then returned to normal production. On the day the test is to be carried out. the conditioning water is landed at the bottom of the well and the test is made without interrupting production except for a brief period required for the conditioning water to consolidate into a continuous column extending to a point well above the test section. With this general description of the process in mind, a more detailed step-by-step description of the process will be clearer. PRELIMINARY PREPARATION OF WELL The Strataflow survey, as it is currently practiced for water entry location, is applicable only to pumping wells. Since the required electrical measurements are made by a special

Jan 1, 1952

Discussion of the paper of Robert Franke, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 79, July, 1913, pp. 1201 to 1205. ARTHUR 0. GATES, Lafayette, Ind. (communication to the Secretary*) :-In connection with the comparison of mechanical crushing efficiencies in Tables I and II of Mr. Franke's paper, I wish to suggest a somewhat simpler way of making this' comparison, based upon what the writer has called the "crushing-surface diagram," as published by him in the Engineering and Mining Journal for May 24, 1913. Such a diagram, based on the data given in Table II, is submitted herewith, Fig. 1, cumulative percentages being plotted as abscissas and reciprocals of diameters (theoretical mesh per inch). plotted as ordinates.. Such a diagram averages the diameters without calculation, and areas upon it are proportional to surface produced, and, in accordance with Rittinger's law, to energy spent on crushing alone.

Jan 11, 1913

By L. Cichowicz, K. K. Millheim

The constant-rate drawdown test performance for a low-permeability, verticany fractured gas well was investigated. A series of gar wells were tested by flowing each well at constant rate until the data could be analyzed using con-ventional radial flow theory. Each well was then shut in to build up. After a sufficient buildup was obtained, another flow Iest commenced but at a higher flow rate than Ihe first test. Again, the well was shut in when radial fiow was obtained. his procedure was repeated for three to four different flow rates. Two wells in the San Juan basin were tested using this procedure. Both wellere fractured after completion, cleaned up and then shut in until flow testing commenced. Test designs of both wells permitted investigation of the most realistic values of egective permeability, wellbore radius and turbulence factor. Also, being able to determine the eflective fracture flow area and vertical fraclure efficiency was inherent with this testing approach. It was observed that fractures in both wells influenced the Pressure behavior for approximately Is to 40 hours (depending on the flow rate) before radial flow was evident. After this time, drawdown data were analyzed using radial pow theory. When a low-permeability gas well has vertitally oriented, induced fractures, the early flow geometry ic. essentially linear. It will be shown how to determine when a flow test has been conducted long enough so lha' the most representative values of effective permeahiiity. wellbore radius and turbulence factw can be calculated. From the linear pressure data, valuable information about The fracture treatment, such as the effective flow area and vertical fracture efficiency, can be determined for vertically froctured wells. Introduction During tests on gas wells in the Sari Juan basin7 initial transient behavior lasted for many days because of the low permeability of some porous media. As a result, stabilized flow performance could not be obtained. If these wells received some type of stimulation treatment, early pressure behavior deviated from conventional theoretical radial Row. When conventional radial flow theory was used to analyze these low-permeability fractured gas wells, larger values of flow capacity and absolute open flow potentials (AOF) sometimes resulted. Wells were assigned open flow poten- tials that proved to be 3 to 10 times higher than the well would sustain over a longer period of production. In some cases where the wells had flowed for longer periods of time during a constant-rate drawdown test, it was noticed that the effective flow capacity appeared to be decreasing with time until a certain value was reached. The early nonradial pressure behavior can be explained If linear flow is assumed. Rusell and Truitt mathematic. ally investigated the vertically fractured well in a bounded area. They showed that early flow behavior was essentially linear and, for x,/x. approximately less than 0.10 radial flow was obtained after short periods of time. Then realistic values of effective permeability and skin could be determined. Scotta experimentaliy studied the vertically fractured well with a heat flow analog. He showed that earb flow was linear, Both studies indicate that, for small values of x,/x,, linear flow approaches radial flow if the well is tested long enough, To help prove this concept of early linear flow caused by induced vertical fractures, two low-permeability gas wells were tested. Both wells received large fracture treatments prior to testing. A vertical fracture was indicated from the analysis of fracture treatments, As anticipated, tests of both wells indicated early linear flow that was later followed by a period of radial flow, Data collected from each well were analyzed. From the well tests, plus other information on each well, the effective permeability, wellbore radius and turbulence factor were calculated. Effective fracture flow areas calculated from test analyses for each well proved to be approximately one-fourth the created area calculated from classic hydraulic fracturing theory: other fractured wells that were tested but not presented in this paper also indicated that the effective fracture flow area was one-fourth to one-third the created area predicted from hydraulic fracturing theory. The vertical fracturing efficiency was estimated from the calculated values of effective wellbore radius and fracture flow area. For the two wells tested, calculated fracture lengths x, were 112 and 105 ft, and the vertical fracturing efficiencies E, were 122 and 183 percent. Development of Flow Model Agnew' showed that most induced fractures below 1,500 ft are vertical. Anderson and Stah15 indicated that most of the fractures they studied were vertical. Thc model proposed for early flow in most vertically fractured gas wells is shown by Fig. 1. This model should approximate early flow behavior until radial flow is reached, at which time a radial model with an effective wellbore radius of 0.5 they will

Jan 1, 1969

By S. Oglesby, A. L. Thomas

Until recently, probably the best means of sampling airborne dusts has been the impinger method. Dust-laden air is drawn into a sampling tube, and the particulate matters separated from the air and collected in the liquid in the impinger. A sample of the suspension is prepared on a slide and counted through a projection microscope. This method is simple and reliable, but it does suffer drawbacks. Since the collected particles must be counted visually, results of the dust count are not immediately available at the time the sample is taken. This seriously impedes studying the effectiveness of dust inhibitors, such as water sprays, or making adjustments in equipment. Greatest disadvantage of all, however, is the tedious task of counting particles in the sample. With the growing desirability of taking more samples, the effort involved in making these counts is a real factor in the cost of dust control. Finally, it is generally recognized that impinger dust counts can be related to health hazard only for specific kinds of dust and under similar conditions. This is because the rather complex mechanism of dust damage depends so much on size distribution of the dust. Counts determined by impinger samples cover a limited size range that does not necessarily corre-

Jan 1, 1960

By A. Kaufman

More than 3 trillion gal of water are used annually by the mineral industry. Of this, approximately 21/2 trillion gal are recirculated, the rest constituting intake water. The major users are natural gas processing plants and phosphate rock, sand and gravel, and iron ore producers. Water was used by the mineral industry for mining (6%), processing (64%), cooling and condensing (27%), and miscellaneous uses such as boiler feed and sanitary purposes (3%). Whereas total water use is dependent on the quantity of material processed and on the particular process requirements of an industry, recirculation is dependent on processing, as well as cooling and condensing requirements, quality of new water intake, and the necessity for treating new and discharged water. Consumed water, on the other hand, is dependent on the quantity of water recirculated, and temperature and humidity in the area. Based on this analysis, an increase in water use by the mineral industry of 21/2 times by 1985 is forecast. Wster intake, however, will only rise 62%, because of a substantial increase in recirculation. In one report of a special series concerning the water resources of the United States, the Senate Select Committee on National Water Resources, 87th Congress, estimated that water demand would double by 1980 and triple by 2000.' In view of the possible water deficiencies that might result from such expanded usage and the need for research guidance, the Bureau of Mines organized and carried out a statistical canvass of water use in the mineral industry for calendar year 1962. The data used in this paper, unless otherwise noted, are derived from that canvass.' The efforts in this paper are devoted toward summarization of the canvass and analysis of the data. SOME DEFINITIONS Intake: Water introduced from an external source for the first time into a given mine or plant regardless of quality. Intake water is also called new water, water withdrawn, or makeup water. Fresh Water: Water suitable for cooking and drinking. Saline Water: Water containing more than 1000 parts per million of dissolved solids. Contaminated Water: Water not suitable for domestic use, but excluding saline water. Recirculated Water: Water reused to conserve intake water. Solutions that are recycled primarily because of fixed metallurgical practices, such as copper leaching solutions containing sulfuric acid, are excluded. Gross Water Used: Recirculated water plus intake water. Also called total water used. Consumed Water: Water that is lost by evaporation, as well as water lost in product. Seepage and transferred water are not considered consumed. The use of either intake or recirculated water may result in consumption. However, because of difficulties in measuring consulmption, consumed water is defined as the residual between intake and water discharged from the mine or plant. Mineral Industry: For the purposes of this paper, mineral industry includes all metal and nonmetal surface and underground mines and their associated processing plants, as well as custom mills, coal washing plants and associated mines, petroleum and natural gas well drillers, natural gas processing plants, and secondary recovery operations. WATER USE IN THE MINERAL INDUSTRY Water used by the mineral industry constitutes a relatively minor fraction of the water withdrawn by all users. Data compiled by the U.S. Geological Survey in 1960 indicate that water withdrawals, exclusive of that used to generate hydropower, approximate 99 trillion gal annually.3 Our data indicate that water withdrawals by the mineral industry comprise only 1% of this total, or 2% of the water withdrawn by industrial users. Use by Industry: Water used by various mineral industries is shown in Table I. The table indicates that close to one-half of the gross water used by the mineral industry in 1962 was used by natural gas processing plants, followed by sand and gravel, phosphate rock, and iron ore producers. The largest aggregate users of water are also the largest users per dollar of product. For example, Fig. 1 shows that the natural gas processing and phosphate rock industries are very large users of water per dollar of product. Their recirculation per

Jan 1, 1968

By Waldemar Lindgren

THE following pages present data accepted by many geochemists and geologists regarding the succession of minerals and the temperatures of formation in ore deposits affiliated with igneous rocks. They also present the individual views of the author on the composition of the solutions that were active and on the mode of deposition. He does not regard these views as speculations or hypotheses but as forming a well motivated and consistent theory. It is not certain, however, that all investigators will subscribe to them.

Jan 1, 1936

By G. H. Kesler, C. E. Dryden, J. H. Oxley

Rates of heat- and mass-transfer from rods to recirculating air were determined within a one-quarter-scale model of a metals deposition bulb. The dependence of local and averaged rates of transfer upon outlet geometry, number of rods, position upon a rod, and airflow rate was established for flow patterns created by radial and tangential air inlets. The results are given a qualitative interpretation in terms of rates and distribution of metal deposition in a prototype deposition bulb. IT is well known that a number of metals can be prepared from volatile compounds containing them by causing dissociation of their compounds to occur at heated surfaces. Examples of such metals include silicon, titanium, zirconium, and aluminum, which can be prepared from their halides. While the ability to prepare high-purity metals by this technique is of importance in itself, the rate of deposition of metal also is important in considering the commercial potential of such a process. If the over-all process of deposition is broken down into separate steps of transport of materials to and from the heated deposition surface and establishment of chemical equilibrium at the surface, as was described in a recent paper,1 then since surface temperatures are usually high and surface equilibrium is attained very rapidly, the rate-controlling step can be considered as either that of transport of reactants to the surface or of transport of products other than deposited metal away from the surface. These two transport steps are related through the reaction stoichiometry. It can be shown1 that the rate and distribution of metal in such a transport-controlled process are determined by the over-all and local mass-transfer coefficients in conjunction with the equilibrium conversions at the hot surfaces. The rate relationship is: w = [KA(y a-y s)] B.E where the bracketed group is the rate of arrival of the reactant at the surface of area A as determined by the mole fraction driving force (y a - y s) and the convective transport constant K. The factor B is the weight fraction of metal in the reactant, and E is the equilibrium fractional conversion to metal. Numerical values of y, and y, are fixed by the vapor composition and the equilibrium compositim of reactant at the surface; and E can be determined by thermodynamic calculations or by experiment. However, values for the convective coefficient K are available generally only for systems of simple geometry, such as cross-flow past a rod or sphere or parallel flow past a flat plate or through a tube. Often it is necessary to work with systems of more complex geometry and in which the vapor flow may not be uniform or exactly parallel or perpendicular to the surface. It is possible, of course, to establish working correlations for these more complex systems by direct experiment; but the experiments usually are costly in both time and money. To circumvent this objection and to aid in arriving at an understanding of the relationships and interactions of the process variables, it is helpful to construct a model of the flow system in which air, water, or other convenient fluids can be substituted for the process vapors and with which mass-transfer measurements or analogous he at-transfer measurements can be made upon a simulated deposition surface. By this means, a large number of measurements can be made in a reasonable time, and the correlation of these results can be applied to the prototype system. Examples of the application of these techniques are to be found in the literature (e.g., Ref. 2). It is the purpose of this paper to illustrate these techniques by description of a model study which was done at Battelle Memorial Institute. The work to be described was of a preliminary nature; the investigation subsequently was extended to develop quantitative relationships among the significant dimensionless transport, geometric, and flow parameters. This more detailed study will be the subject of a future paper.

Jan 1, 1962

By Herman Garlichs

THE development of the extensive Southeast Missouri deposits greatly preceded that of the Iowa and Wisconsin deposits. It began about 1720 at Mine La Motte and other localities, and has continued uninterruptedly to the present time. It is estimated that this district produced about 184,000 tons of lead in the year 1916, having a value of approximately, $25,000,000. This is a new high record. The Southwest Missouri orebodies were hardly known before 1845 and were not extensively developed until 1870: Lead production in South-west Missouri for 1916 was 38,788 tons. Oklahoma produced 14,399 ,tons and Kansas 2,345 tons, making a total for Southwest Missouri, and the adjoining districts in Oklahoma and Kansas, of 55,532 tons of lead. The first metallurgists in Missouri were the Indian and the hunter. The early settler learned to procure his bullets either by melting ore in his camp fire or by throwing pieces of galena on an old stump and depending on the usual roasting and reaction method to obtain the metal. A little more refined method was to arrange two flat stones in the form of a V. Wood and galena were placed in the furnace and ignited. As heat developed, some of the metal was extracted and molded into bullets. The next step in utilizing the lead ores was the log hearth. All lead in Missouri was smelted in this crude affair before 1820. It was built on sloping ground, and consisted of a hearth of stone, surrounded on the front and two sides by a stone wall. The wall was 7 ft. high in front. The top and rear end were left open and in front an arch or opening was made, forming the eye of the furnace. In front of this a pit was dug in the ground, to receive the molten metal. Large logs were rolled in at the back and made to rest upon ledges formed inside, to raise them from the hearth and to give a draft. These logs filled the entire width of the furnace. Small split logs were then set up around the two sides and the front, and the ore was piled on until the furnace was full. Finally, the mass was covered with logs and fuel until the ore was completely surrounded. A gentle heat was started, which was raised very gradually. After 12 hr. the heat was increased and continued for 12 hr. more, 24 hr. being required, for each smelting. The furnace treated about 5,000 lb. per 24 hr. and the ore yielded about 50 per cent. of its metallic lead. A considerable quantity of the ore was not desulphurized, and fell between

Jan 7, 1917

All branches of our profession may look back 'with pride upon the patriotic service rendered by engineers during the war. That war has been won. The mortal danger which it threatened has been averted. But the effects of the torture inflicted by it still remain, a fever in the blood of the body politic. Fever begets delirium and, unless its course be checked, has a tendency to produce convulsions. The only safe course is to take immediate steps to allay the fever. The seat of the present trouble is industrialism; as production is at the foundation of civilization, a diseased condition there carries pain and consequent unrest into every member of the organism. Who shall supply the cure? Quack doctors, nostrums in hand, rush forward from all directions promising to perform miracles. But sane men know that no miracles, though invoked by star gazers of purest intention, will prevent or accelerate the orderly operations of the laws of nature and of human life. Delirium must be controlled by the firm, gentle hand of intelligent, sympathetic authority. Fever must be allayed first by removal of all poisons from the system, then by consistent ministration of cooling, quieting restoratives, then by simple, wholesome nourishment. Nature will, under such treatment, supply the permanent cure.

Jan 12, 1919

By George E. Kruger, William F. Butler

The less developed nations maintaining a free enterprise economy (to which this chapter is addressed) have real and substantial opportunities to lay a foundation for general economic progress by using their mineral resources. Most of these nations have mineral resources which could be developed. By seizing these opportunities, nations seeking rapid economic development can secure a source of foreign exchange earnings to finance the imports needed for growth and, at the same time, increase the technical knowledge and well-being of an important part of their population. History clearly shows the manner in which most of the currently industrialized nations have used mineral resources to support their development. Indeed, few nations have managed to achieve a high level of income without a firm base of mineral resource development. The main exceptions appear to be the Netherlands, Switzerland, Denmark, and New Zealand, and the last two have based their prosperity on a highly efficient agriculture. Economic growth in the United States, the United Kingdom, Canada, France, Germany, and Russia was importantly based on the use of indigenous mineral resources. Despite this record of accomplishment through mineral development, many of the currently less developed nations are not taking advantage of the opportunities available in the mineral field. Restrictive laws or practices in many such nations operate effectively to prevent development of mineral resources. This failure to grasp real opportunities for development is based on a series of arguments that the mineral field offers few substantial and attainable advantages. Among these, the following propositions appear the most important:

Jan 1, 1964

By GERALD H. HUTTON

SINCE the inception of dredge mining, the attention of engineers and operators has been directed primarily toward mechanical improvements and refinements calculated to, reduce operating costs and to increase recoveries. The result has been to develop an efficient excavating and value-saving machine, which, in some instances, has an actual capacity of 15,000 cu yd. per day. Steel hulls and superstructures minimize the risk of destruction by fire and lengthen the life of the plant. Dredges now restore, to some extent, agricultural possibilities to mined ground. Large buckets, with correspondingly heavy parts, are able to handle heavy wash and massive boulders. Mechanical weaknesses have been strengthened. The use of manganese steel in bucket lines and tumblers permits the application too the bank of a digging force that can be withstood only by solid material, such as rock, cement or frozen ground. Various alloys of steel have been applied to certain duties and experiments in their heat treatment are still progressing. Haulage by tractor or truck is in common use. Discarded and worn steel parts are repaired or rebuilt by the use of the oxy-acetylene flame and the arc-welding machine. Gold and platinum saving is more efficient, although still subject to improvement. Dredging for tin ore is in successful operation. Crews are now highly specialized and experience has developed improved methods of work; particularly in the manipulation of dredges to build levees of tailings and to leave open waterways where desired. To sum up by the distribution of overhead expense over several units, ground under favorable conditions can now be dredge-mined for 5)2 c. per cu: yd., in spite of the increase in cost of supplies, power, and labor during, the past few years. Improvements in prospecting methods, however, have not kept pace with mechanical developments. Standard practices of ; testing ground today produce only wide approximations of values; although they obtain information concerning the character of the deposit and bedrock. It is interesting to note that few important changes in the methods of ten years ago are .to be recorded; the latest comparisons between pros¬pecting results and mined recoveries-have been at such variance as to cause confusion to the operator, and, in a degree, the sacrifice of the confidence of the capitalist. On this account, and because the growing scarcity of dredging ground. demands closer calculations on the part of the engineer, this appeal for collaboration and

Jan 1, 1921

By V. Lessels, D. J. Buckwalter, D. H. Rose

At White Pine Copper Co.'s operation in the Upper Peninsula of Michigan, the company has been losing more than four lbs of copper in each ton of sand tailings. With an average rate of 12,000 tpd of sand going to the tailing pond daily, the company has been losing more than 14 million lbs of the red metal annually. With an eye aimed toward lessening this loss, White Pine engineers in 1959 initiated a study on techniques for recovering this "lost" copper from the sands. Inasmuch as the flotation operation was considered to be optimized, a logical approach seemed to be leaching. For various reasons ammonia, ferric chloride, acid, and biological leaching were ruled out as impracticable. This led to a consideration of cyanide leaching as practiced in the precious metals industry.

Jan 8, 1967

By Richard H. Terhune

The use of water-cooled breast-jackets or cinder-tap blocks is a great convenience in lead-smelting, even when siliceous slags are made. If the charges are at all basic it is almost imperative. Jackets of riveted wrought-iron or steel are expensive; those of cast-iron are liable to crack; those of bronze are costly and not durable, being easily penetrated by tapping-bars or destroyed by streams of matte impinging against them. To overcome these objections I introduced at the Hanauer works, in April, 1886, castjackets of steel, which have been in constant use since that time and are to-day as good as new. These jackets were made for us by the Chester Steel Castings Company, of Chester, Pa., at a cost of ten cents a pound at the works of that company. The metal is 5/8-inch thick, and the jackets were cored and tapped for l1/2-inch bushings, affording two large holes for the removal of dirt and incrustations. The same holes are used for feed- and discharge-water through 3/4-inch pipe. I hope the successful introduction here of cast-jackets of steel will lead to their more extended use in all branches of metallurgy where water-cooled surfaces are severely taxed, and where the size and thickness of the castings are not unfavorable to the production of a sound article, impervious to water and of high tensile strength.

Jan 1, 1889

THE fifth annual convention of coal-operating men, with the usual exposition of coal-mine equipment, was held at Cincinnati, May 7 to 11 inclusive, and was fully up to the high standard set by previous years. This spring meeting has come to be one of the most helpful services to industry performed by the Ameri-can Mining Congress and a center at which operators and engineers easily and quickly get into touch with the newest and best things in practice and equipment. Over 200 exhibitors showed this year and very little if anything that is new `failed to be shown. The ex-hibits were well arranged and adequate rather than elaborate. They attracted the careful attention of the members and guests of the Congress, admission being by badge rather than by ticket sold to, the general public. Eight sessions were held for reading and dis-cussion of technical papers, one for Management and

Jan 6, 1928

By F. H. McDowell

The increasing interest in the subject of electrical separation warrants the addition to what has already been written of a few lines covering the practical workings of the Tilly Foster mill under the direction of Mr. E. S. Moffat, General Manager. Since my last paper was presented to the Institute, Mr. S. P. Tomkins, the superintendent, has had thrust upon him for solution several problems complicated by the introduction of new conditions. 1. The richer portion of the lean ore dump, and that nearest the railroad track, having been worked up in 1890, the handling of the balance, including a largely increased amount of rock, could only be accomplished at an increased cost. 2. The tailings had accumulated close about the mill to such an extent that arrangements had to be perfected to move them further away.

Jan 1, 1893

By W. W. Anderson

A formula for quantitative efficiency is proposed, in which the efficiency value is a function of the improperly distributed material at the, gravity of separation effected by the cleaning equipment. The misplaced material is expressed as a percentage of the total material discharged from the equipment. Numerous examples are given, demonstrating application of the formula to various types of separation, including multiple-product separations.

Jan 1, 1950