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By G. A. Swanquist, E. M. Morales

INTRODUCTION The idea of water management and control at the Church Rock Mill operations began to take shape in February 1979. At that time, we were already investigating the feasibility of decreasing the fresh water requirements so that the solids would become the limiting factor in tailings impoundment utilization. The area for solution evaporation could be kept at a fraction of the normal requirements under the standard process of full water usage. The Church Rock Mill is an acid leach circuit followed by solids/liquid separation with thickeners in counter current decantation, and solvent extraction. Following the normal design of acid leach circuits, reuse of tailings solution was not incorporated in the original mill process design. INITIAL WATER CONTROL INVESTIGATIONS The investigations to decrease the fresh water requirements centered around modifying the grinding circuit from the present semi-autogenous grinding (SAG) mill in closed circuit with hydrocyclones, to open circuit grinding with a rod mill. The open circuit grinding with the SAG mill and rod mill in series had the potential of decreasing the water requirements for grinding and leach dilution by approximately 50% or 1.4 m3/min (300 gpm). The grinding pulp density would be maintained at 70 to 72% solids, and the leach dilution to 50% solids would be accomplished with acid tailings liquor recycle. In such a grinding circuit arrangement, the SAG mill would provide the primary or coarse grind, and the rod mill would be used for the fine grind. By the SAG mill and rod mill series grinding method of water control and other secondary water controls in various places downstream from the grinding circuit, the required necessary evaporation area was estimated at 120 acres of liquid surface. A second method of water control at grinding was investigated. A two-stage cyclone classification circuit appeared to have a good potential of achieving the same water reduction at a much lower capital and operating cost. However, in retrospect, this would not have been a viable method since a high slime recycle load would have been established hindering classification. The use of reagents to neutralize the acid tailings solution was not considered seriously at that time, since it would have materially increased operating costs, although it would have also allowed more tailings solution recycle and consequently, less fresh water usage. However, with the tailings solution deposition area available at that time, it was not then necessary to incur the high cost of neutralization. The control expected by the series grinding of semiautogenous and rod mills would have been sufficient to maintain a water consumption/evaporation equilibrium well in line with the available land area. IMPLEMENTATION OF NEUTRALIZATION OPERATIONS During the summer of 1979, the UNC Church Rock Mill experienced a tailings dam breach which resulted in a prolonged mill shutdown. Upon resumption of operations at the end of October 1979, tailings deposition was restricted to a small portion of the tailings impoundment area. Figure 1 shows the general tailings area and the limits of the present deposition area in the central part including the borrow pits. These borrow pits had been excavated to provide materials for tailings dam construction. Immediately after resumption of operations, it became evident that it would be necessary to control the quantity of liquid to be evaporated because of the small confined area available for tailings solution deposition and to maximize the deposition time in the tailings area. The water control required had to be exercised on a large scale, and to be in operation as quickly as possible. An obvious solution was to reuse the tailings liquor in mill process. Immediate steps were taken to install the necessary equipment for tailings neutralization on an interim basis. Anhydrous ammonia was selected as the primary neutralization reagent since it was the quickest system that could be placed in operation. Previous laboratory tests indicated fair results with ammonia neutralization. Such a system required a minimum of installed equipment and handling. INITIAL NEUTRALIZATION OPERATIONS Actual neutralization operations began on November 26, 1979. The raffinate solution which normally would have been discarded was pumped to a 3.7 m (12ft) diam by 4.3 m (14ft) tank for reagent contact, see Figure 2. At this tank, anhydrous ammonia was added directly from the tanker trailers and controlled at pH 7.0 nominally. Agitation was provided by air sparging. The neutralized product formed a highly viscous slurry in the grinding circuit which resulted in pumping and cyclone classification problems.

Jan 1, 1982

By W. E. Rudolph, R. E. Baylor

DUE to its location in the Atacama Desert, one of the most barren of the earth's surfaces, Chuquicamata's water supply presents unusual problems. Yearly rain-fall averages less than one tenth of an inch at the plant. However, there are summer showers above 12,000 ft in the Cordillera to the east, the resulting run-off flowing through old river valleys buried beneath more recent volcanic formations, to be impounded within sediment-filled basins. This water emerges at springs where the outlets of these basins are blocked by lava flows, and here are formed the small streams which feed the only important river of the region, the Rio Loa. Chuquicamata's water is obtained from these springs and rivulets. [ ] The map above indicates four pipe lines from which potable and industrial water are supplied. Potable water, amounting to 4500 metric tons per day, is conveyed in the Toconce pipe line from springs 59 miles due east of Chuquicamata. This water is used not only for drinking, but also for boilers and other needs requiring high quality. For industrial water at the oxide plant, there are two 12-in. pipe lines from the Rio San Pedro, carrying a total of 17,000 metric tons per day of slightly brackish water. This water is at present used mainly for leaching and for hygienic purposes. Water Source Found For the present and future needs of the sulphide plant, it was calculated that at least 32,000 metric tons per day of make-up water would be required. For this purpose, a pipe line of 44 miles length was constructed to bring in the entire flow of the Arroyo Salado, one of the eastern tributaries of the Loa. The salt content of this water is so high (over 5000 parts per million of solubles, mostly chlorides) that it is highly detrimental to farming, and the Chilean Government had been studying projects to separate these waters from others of the Loa system in order to improve agricultural conditions in the fertile valley of Calama. So it happened that the Government was willing to award rights to the Arroyo Salado waters under agreement whereby the Mining Company removes waters from the Rio Loa system above Calama for all time. The outlet of these waters, after serving their purpose at the new concentrator and leaving the plant in tailing, is the Salar de Talabre, an old salt lake which presents fully ten square miles of surface to serve as an evaporating pan, the outlets having now been blocked by dams. Here the dry climate of Chuquicamata is a favourable factor, evaporation averaging slightly above 1/4 in. per day. The Toconce and San Pedro pipe lines have been functioning from 26 to 34 years, and through the use of special cleaning tools which were developed at the plant, as well as deaeration of the more active Toconce water, these pipes are now maintained at capacities which do not diminish as years go on. Constructing the Dam The Arroyo Salado pipe line design and construction involved certain special and interesting features, and inasmuch as this line and its intake works are solely for the needs of the new sulphide plant, more detailed description is given. The waters are impounded at a gravity dam constructed of concrete to a height of 100 ft above the river bed, keyed into the precipitous Dacite walls of the narrow canyon (barely 6-ft wide at the bottom, only 25-ft width at 50 ft above). A small secondary dam was built 100 ft down stream from the main dam, providing a pool of 15-ft depth to protect the main structure from flood flows over the spill-way during the rainy season. A system of four 36-in. syphons was designed for discharging these flood waters from the lower depths of the lake, in order to avoid eventual sedimentation behind the dam. The lake has a length of 3300 ft, and its water level is controlled by an adjustable spillway permitting draw-down of eighty inches, amounting to 41,000 metric tons of available capacity. This regulation is necessary because of wide fluctuations in stream flow between day and night due to freezing of feeders. During the construction of the dam the entire river flow was handled within a 36-in. pipe line some 2000 ft in length. As the excavations proceeded

Jan 1, 1952

By G. M. Willis, F. L. Hennessy

The oxygen pressure in equilibrium with silver and Ag2O-B2O3 melts has been measured between 800' and 900°C, to obtain the thermodynamic properties of the liquid. The compound Ag20. 4B20:1 appears to exist in the liquid, which shows marked heat content and entropy effects. A KNOWLEDGE of the thermodynamic properties of binary liquid silicates, borates, and phosphates would be of considerable assistance in the interpretation of the behavior of multi-component metallurgical slags. However, the literature contains comparatively few studies of the thermodynamics of binary slags. The system Ag20-B,O, attracted our attention as it was known to give a single liquid phase,',' in which high contents of silver could be obtained (up to 61 pct Ag according to Foex2). Further, it would be expected that the partial pressure of oxygen over melts in equilibrium with metallic silver could be used to determine the activity of Ag2O in the Ag,O-B,O, system. In many respects, it may be expected that the reaction of a basic oxide with boric oxide would be analogous to its reaction with silica. Liquid immiscibility frequently occurs in both borate and silicate systems. With B2O3 and SiO reaction with a basic oxide presumably involves a breakdown of the three-dimensional network of the acid oxide by reaction with oxygen atoms common to more than one silicon or boron atom. Ag2O-B2O3 was therefore investigated as a model of a slag system in the hope that its thermodynamic properties would assist in understanding those of other systems. Several methods for determining the activity of a component in a slag have been described in the literature. Chang and Derge" used high temperature electromotive force measurements to obtain the activity of SiO2 in CaO-SiO2 and Ca0-Al203-Si02 slags, but the cell reaction in their work is not clear. low has used rate of volatilization and vapor pressure measurements combined with phase diagrams to obtain activities in the systems KO-SiO,, Na,O-SiO, and Li,O-SiO," and PbO-SiO26 Taylor and Chipman7 extrapolated their results for the distribution of FeO between liquid iron and CaO (+Mg0)-FeO-SiOl slags to obtain the activity of FeO in the binary FeO-SiO2 system. In principle, one of the most direct methods for obtaining the activity of a metallic oxide in a phase is by comparison of the equilibrium oxygen pressure for the system metal-pure oxide with that of metal oxide-containing phase. Schenck and othersa have studied the stabilization of Ag2O on combination with other oxides (MO,) in the solid state by measurements of the oxygen pressure in systems of the type Ag-Ag,O-xM0,-MOy-0, (gas). Schuhmann and Ensio" have determined the activity of FeO in iron silicate slags in equilibrium with solid iron, using CO/CO2 mixtures to establish known partial pressure of oxygen. Although the method gives the activity of FeO without ambiguity, the slag is not a binary system, and interpretation of the results in terms of the hypothetical binary system FeO-SiO, is not possible. If a metal is solid at temperatures at which the properties of the slag containing its oxide are to be studied, this method has the considerable experimental advantage that the metal can be used as the container for the slag, and contamination by contact with refractories is avoided. In this work, crucibles for Ag2-B,O, melts were made from silver, and the liquid brought to equilibrium with definite pressures of oxygen gas. The oxygen pressure PO, thus fixes the activity of Ag20 in the liquid silver borate. For the reaction at a given temperature. is substantially constant, is directly proportional to the square root of the equilibrium oxygen pressure. Varying the oxygen pressure changed the silver oxide content of the liquid and it was possible to obtain the activity of Ag2O over a range of composition. Experimental Procedure In principle, the method consisted of bringing melts in silver crucibles or boats to equilibrium at a fixed temperature under a definite pressure of oxygen and analyzing the glass after solidification. Materials: B2O3 glass was prepared from A.R. quality boric acid by fusion in platinum. The silver

Jan 1, 1954

By C. R. Knopp

Gas-oil relative permeability ratio is an important relationship in oil reservoir predictive calculations. A correlation has been developed from 107 gas-flood k/k tests on Venezuelan core samples. The correlating parameter is based on restored-state water saturation tests and' is applicable to both consolidated and poorly consolidated sandstone reservoirs. Data of the correlation show that there are no distinguishah1e differences between the mass-data groupings for the two c1assifications A procedure is recommended for running .sufficient relative. permeability analyses to compute a geometric mean of the sample group. The geometric mean is more representative of the total core, and probably the entire reservoir. For example, while only one in four of the k,,/k,., test curves agreed closely with the resultant correlation of this report, the geometric mean curves of the 16 suites (three samples or more). showed good agreetment ill three cases out of four. INTRODUCTION The gas-oil relative permeability ratio is an important, fundamental relationship in most oil reservoir predictive calculations. Predictive calculations are made to estimate future reservoir production characteristics and ultimate oil recovery. The k1,/k2, relationship is specifically needed to relate the surface gas-oil ratio to the reservoir oil and gas saturation, and to calculate the relative movement of these phases within the reservoir whenever some of the more complex driving mechanisms are present. Laboratory k1/k2, tests are not generally run as a routine analysis. Consequently, k1/k2 data often are not available when needed because the cost of laboratory work could not be justified or the need for such data had not been properly anticipated. When laboratory k1/k2, data are available, they are often very difficult to interpret. For example, wide divergence is sometimes shown in a family of k1,/k1, tests representative of the producing horizon in a single well. With these considerations in mind, a study was made to determine if a relationship might exist between the k1,/k2, curve and some other simple laboratory test criteria. The most probable k1/k2, curve correlation for Venezuela described in this paper is the result of the investigation. The presented correlation defines the most probable gas-flood k,,/k,, curve through the medium of air-water capillary displacement and centrifuge water saturation tests. The laboratory procedures of these tests are. relatively simple, and inexpensive; test data should be. widely available- from routine analysis. DATA AVAILABLE, LABORATORY METHODS The report correlation utilized 107 gas-Hood k1/k2, tests run on sandstone cores of Venezuelan reservoirs. Table 1 is a general tabulation of data pertinent to the tests, while Table 2 summarizes the data. Thetests include 96 from Western Venezuela and 11 from Eastern Venezuela. Eighty-two- of the 107 test samples were sandstones that varied from poorly consolidated to-unconsolidated; 25 were consolidated. The average sample porosity was 26.7 per cent and the average permeability was 1,121 md; these values typify the better sandstone reservoirs of' Venezuela. The Welge gas-flood technique,' based on fundamental Buckley-Leverett frontal displacement theory, was introduced in about 1952 and is widely accepted in the industry. The laboratory procedure is relatively simple, rapid, and can be performed on small core samples. While there have been some minor variations in sample preparation and laboratory procedure in the tests used for the correlation, these tests can be generally summarized as follows. The core sample was first sol vent-extracted and dried. Connate-water saturation was restored by the oil-flushing or evaporation-blow down methods. At the beginning of gas flood the hydrocarbon pore volume was completeiy saturated with the test oil phase. Unsteady-state gas-oil displacement then began with the injection of nitrogen or helium. while the displaced oil and gas phases were incrementally metered at the out-flow face. From the test data, the k,,/k,, curve was calculated by the Welge method.' The individual oil and gas relative permeabilities were also calculated." CORRELATING PROCEDURES In attempting to establish a basis of correlation, we found that broad mid-range sections of 105 of the 107 k,,/k,, test curves could be closely duplicated by a straight line. Only two curves did not show a degree of linearity in this region. Correlation-curve definition parameters were subsequently developed from this observation of consistent mid-range linearity. Possible correlating variables were limited to the physical properties measured on core samples that (1) were widely available as common test data and (2) could be easily and cheaply obtained through future laboratory work. The more obvious possibilities were porosity, permeability and

Jan 1, 1966

By ROBERT E. CROCKETT

MAGNETITE mining and milling in New York, New Jersey and Pennsylvania continued to remain comparatively inactive during 1933, owing to the low rate of output of the steel industry and also to unrestricted importation of foreign ores. However, some improvement over conditions existing in 1932 was noticeable, particularly in New Jersey, where one plant, that of the Washington mine of the Alan Wood Mining Co., at Oxford, went on full production in August. At Lyon Mountain, N. Y., the Chateaugay Ore and Iron Co. resumed mining and milling operations in October, on a reduced scale, principally to provide employment during the winter months. The Chateaugay company produces a special low-phosphorus pig iron. During the year they obtained a contract to supply their product for use in the manufacture of the suspension cables of the New. Golden Gate Bridge.

Jan 1, 1934

By AIME AIME

General Local Committee.-John Fritz, Chairman; A. B. de Saulles, Vice-Chairman.; R. M. Bird, Treasurer; Henry S. Drinker, Secretary; Robert H. Sayre, E. P. Wilbur, Charles M. Dodson, Abraham S. Schropp, E. M. McIlvain Archibald Johnston, A. B. Fichter, C. G. Convers, W. A. Wilbur, Garrett B. Linderman, Frederick Conlin, George Pettiuos, Albert Brodhead, Garrett L. Hoppes, M.B. Cutter, H. J. Seaman, C. A. Matcham, B. F. Fackenthal, Jr., A. L. J. Queneau, Geo. R. Elder, Eldridge Wilbur, William H. Chandler, Mansfield Merriman, Joseph F. Klein, William S. Franklin, William Esty, Joseph AN'. Richards, Howard Eckfeldt, John D. Irving. Transportation Committee.-H. J. Seaman, C. A. Matcham, B. F. Fackenthal, Jr., A. B. Fichter, A. L. J. Queneau, Henry S. Drinker. Hotel Committee. -Garrett B. Linderman, Charles M. Dodson, W. A. Wilbur, Garrett L. Hoppes, Albert Brodhead. Steering Committee.-William S. Franklin, William Esty, John D. Irving, R. M. Bird, the members of the Tau Beta Pi Society of Lehigh University. Committee on Meetings - William S. Drinker, Joseph W. Richards, Howard Eckfeldt. Entertainmment Committee.-W. A. Wilbur, E. M. McIlvain, Archibald Johnston, A. B. de Saulles, G. G. Convers,.A. L. J. Queneau, Garrett B. Linderman, Frederick Conlin, George Pettinos, Garrett L. Hoppes, Henry S. Drinker, William S. Franklin, Eldridge Wilbur, Robert M. Bird, Secretary. The opening session was held at 8.30 p.m., Wednesday, February 21, 1906, in Gymnasium Hall of Lehigh University, which had been tastefully decorated with flags and bunting. Dr. Henry S. Drinker, President of Lehigh University, and Secretary of the General Local Committee, called the meeting to order, and welcomed the Institute to the Bethlehems, where its first meeting, after its organization in May, 1871, at Wilkes-Barre, was held in August, 1871.*

May 1, 1906

By Boris J. Kochanowsky, Burke O. Trafton

Because of the strict requirements on the quality of limestone that are dictated by the users, the operator was compelled to find new approaches to produce a product of uniform and acceptable quality. The raw material is controlled and monitored every two minutes by a special computer in order to ensure its quality. The required minimum and maximum quality constraint had an adverse effect on performance and consequently cost. In order to improve this performance, a Monte Carlo simulation model was developed and tested for the optimal truck allocation. The input data is based upon the distribution of equipment performances and costs.

Jan 1, 1969

By G. C. Wallick

Since the appearance of the paper, "Solution of the Equations of Un-steady State Two-Phase Flow in Oil Reservoirs," by W. J. West, W. W. Garvin, and J. W. Sheldon,' a two-fold investigation of this subject has been carried out. One objective of the investigation has been to deter-mine the feasibility of solving such problems 7on a medium-size com-puter such as the Datatron*, and the other objective has been to in-vestigate the application of such cal-culations to experimental and theo-retical petroleum reservoir research. In the first Datatron calculations, the fluid and rock properties published by West, et al, were used, together with the published equations describ-ing the system. Details of the formu-lation not given in the original paper are discussed in the Appendix to this note. Reference should be made to the subject paper for the complete equations and defintion of symbols. An unexpected result of this in-vestigation was the discovery that the linear solution published by West was in error. Thus, in addition to describing the Datatron solutions and to discussing certain numerical diffi-culties which will be encountered if one uses the published method of solution, the purpose of this note is to indicate the nature of this error. LINEAR FLOW Since the linear case requires a minimum amount of scaling, a fixed-decimal point Datatron program was written for the one-dimensional flow problem and an attempt was made to duplicate the solution described by West. In the case described, fluid was produced at a constant rate, Q, until such time as well pressure reached 0.04. Production was then continued at constant pressure. From the constants and curves given by West it was determined that the ini-tial constant production rate could be approximated by Q = 0.007. An ini-tial dimensionless time step ?t = 0.434 X 10 - "as used, and each suc-cessive time step was doubled until a value of = 0.444 was reached. This constant interval was then used for the remainder of the solution. In subsequent solutions, several varia-tions in the time schedule were em-ployed, including smaller time steps and slower rates of increase in the time steps. In all cases, almost identical results were obtained regardless of the time schedule employed. However, as described below, it was noted that the time schedule had some influence on the rate of convergence of the solutions. As a check on the accuracy of the solution, the cumulative production at each time step was calculated using the two methods described in the Appendix. Satisfactory agreement was observed with the differences in these two values of the order of two parts in 50,000. It should be noted that the mass balance check as described is of questionable value, particularly with regard to the well pressure and saturation. This is especially true in the radial solution where pressure and saturation values near the wellbore would make only a negligible contribution to the numer-ical integration. It is believed, how-ever, that such a comparison is ot value in determining the over-all accuracy of a solution. In comparing the Datatron solu-tion with that published by West it was discovered that in the later stages of depletion, the pressures near the well declined more rapidly in our solution than in the West solution, and that the limiting well pressure of 0.04 was reached at an earlier time than that originally reported. It thus became evident that it would be impossible to duplicate the production schedule described by West and a constant rate of production was maintained until the well pressure was equal to 0.0. A representative comparison of the results published by West with those obtained in this investigation is shown in Fig. 1, which is a plot of GOR as a function of cumulative recovery. These two curves should be in agreement until a cumulative recovery is reached which corresponds to a well pressure of 0.04 — for the Datatron solution, a recovery of approximately 5.6 per cent. Actually, a major disagreement is evident. Subsequent correspondence

Jan 1, 1958

By George H. K. Schenck, Peter G. Donald

There is an accelerating acceptance of change by management of cement companies. Diversity of response is noticeable in efforts across the country to reverse the downward trend in profits that brought margins in 1966 to the lowest point in 20 years. New concepts are emerging among managers as they seek to increase the efficiency in use of the basic corporate resources of men, capital and technology. The shift towards computerized control of cement manufacturing is making new gains as is diversification of cement companies into allied fields such as production and sale of natural and light- weight aggregates, crushed stone and concrete products. Increased interest in special products such as white cement and further moves overseas are also significant. Perhaps the most dramatic event of recent years occurred in Washington at hearings before the Federal Trade Commission where cement producers split on whether there should be FTC guidelines that would prevent ownership of ready-mixed concrete producers by cement companies.

Jan 4, 1967

By J. J. Foster

MOST of us will, I think, agree that never before in the history of the coal industry has the human side of our business been so important as today. Since, even in wholly mechanized mining, labor cost is such a large percentage of out total cost we are all deeply concerned not only about the present attitude of our employees but particularly about the future, when the industry returns to a "survival of the fittest" basis. Many things could and should be done about our employee relations in the coal business. Failure to recognize these obligations and do something about them may lead to serious consequences, the least serious of which will be the loss not only of many of our better employees but a large portion of our potential employees, as they graduate from our schools to other in¬dustries. Some of these things should be handled by the industry as a whole whereas others should be done by individual companies. Due to varying conditions and size of organizations it would, at best, be necessary to vary a program to meet the individual needs of each operator.

Jan 1, 1945

By Tenney, J. B.

DEVELOPMENT of complex ores in the south- western part of the Rocky Mountain region has been retarded by the prohibitive distance to the nearest suitable zinc treatment plants. In the north- western and central Rocky Mountains the building, cluring tlie past decade, of electrolytic zinc plants at Anaconda, Great Falls, Trail, and Burke has tremendously stimulated the mining and exploiting of such .ores, greatly increasing the production of lead, zinc, copper, gold, and silver. Selective flotation permits the making of high-grade led, copper, and zinc concentrates. If the zinc concentrates could be made free from lead, copper, gold, and silver, they could be shipped economically to Mid- Western retort plants designed for such concentrates. Unfortunately a considerable proportion of the precious metal content accompanies the zinc blende in the ores of this region. Although some of it is saved in 'retort residues, the treatment cost is thereby increased so materially and the proportion saved so small, that .concentrates of ordinary grade cannot stand treatment charges and freight.

Sep 1, 1928

By A. C. Fieldner

COKE and by-products have prime importance in the war program. The past year was marked by the construction of new and the rehabilitation of old by-product and beehive ovens and by the increase of production from existing plants to practically 100 per cent capacity. W. T. Brown's paper, "Plan to Improve Blast-Furnace Coke," presented at the Fuels Conference in St. Louis, Sept. 30, showed how the blending of low- and high-volatile coal improved the physical properties of coke and that improvement of the quality and uniformity of coke favored an increase of blast-furnace capacity- a vital need in the war program. Others in the industry have likewise increased production of coke or recovery of by- products by various innovations or changes in operation. Recognition of the value of pooling these developments for the benefit of the entire industry led to organization of a survey of coke- oven plants and blast furnaces by the Bureau of Mines in co-operation with the Solid Fuels Co-ordinator with a view to improving metallurgical coke production and recovery of by-products. This survey is being conducted with the help of an advisory committee consisting of representatives of the Bureau of Mines, the Solid Fuels Co-ordinator, the War Production Board, and the blast-furnace, coke-oven, and coal-mining industries.

Jan 1, 1943

By W. C. MENDENHALL

THE problem of maintaining the mining industry is two-fold; finding new supplies in the face of increasing difficulties, and making such advances in the arts of extraction and preparation as to use supplies of lower grade. Progress in mining and reduction methods and in transportation makes ore today of that which was waste yesterday. These are the fields of the metallurgists and the transportation engineers. The geologists and mining engineers must work together on the problem of ore finding. As the old prospector fades from the scene, men with equal hardihood and patience and equal power to meet the physical obstacles which confront the seeker after ore, must take his place, armed with all that has been learned from human experience about the causes, the controlling conditions, the indications, and hiding places of the metals. Such a seeker is dealing with some of the most complex and obscure of natural phenomena. In nature's laboratory, tremendous forces are at work. Tempera-

Jan 1, 1926

F A. THOMSON, president of the Montana School of Mines, gave an interesting talk on mining schools of the past, present and his ideas of the future before a recent meeting of the Montana Section of the A. I. M. E. He covered the history .of the various mining schools and com- pared the three main types of schools; those attached to or forming part of an endowed college or university such, for example, as' the Columbia School of Mines, the Mining Department of the Massachusetts Institute of Technology and the Mining Department of Stanford University. These resemble in a general way the second class, those attached to the state universities and colleges. The schools of this general type have had varied success.

Jan 1, 1928

By Hans Lundberg, Basil T. Wilson, H. Steuart Scott

FOR the benefit of those readers who may not be in close touch with present practices in the geophysical prospecting for ore, brief reference will fiat be made to the advantages and shortcomings of the methods to be discussed. Magnetic and electric methods are generally accepted as the most useful for ore prospecting. By magnetic methods, magnetic intensities that are not normal may be recorded and outlined. From these can he located concentrations of such highly magnetic minerals as magnetite or pyrrhotite, which sometimes occur in such large masses that they are of economic value in themselves. More often. however, these magnetic min¬erals are associated with others, such as copper, zinc, lead, gold, and silver, which, if existing in sufficient concentration and quantity, may constitute valuable ore bodies. It is therefore only when pyrrhotite and magnetite are present in these bodies that the magnetic method can be used to indicate their presence.

Jan 1, 1945

By JOHN R. SUMAN

OVERWHELMING proof of the importance of oil in a modern national economy is afforded by the present European War. Treat¬ies and national boundaries have been cynically violated to secure greater supplies of the precious fuel. Petroleum substitutes have been desperately, and far from successfully, sought. The whole German military theory of the drang nach Osten, the drive to the East, is directed at cutting the British supply of oil and securing a supply for Germany. This is a war of machines, and the machines of war feed hungrily on oil. In view of this fact, it is surely comforting to know that we are living today in a nation which has surpassed all the rest of the world not merely in unearthing the raw supplies of petroleum which lie beneath its surface but also in every phase of the industry in mining, refining, processing, production, and distribution.

Jan 1, 1941

By William R. Rumbold

THE Kinta valley in the State of Perak, one of the largest of the Federated Malay States, is probably at the present time the richest alluvial tin-district in the world, Perak producing from 20,000 to 25,000 tons of tin annually, and the Kiuta valley being the chief producer. The valley runs approximately north and south, and is 30 miles long by 12 wide. It is very flat, the mountain-ranges on either side rising abruptly from the plain, that on the east being the great Central range of the peninsula, and that on the west a subsidiary range marked " Kledang " on the map, Fig. 1. The valley is drained by the Kinta river, which rises in the eastern mountain range and flows south to join the Perak river, being joined by numerous streams from both mountain-ranges. The rain-fall is heavy, averaging annually about 90 in. The whole country is covered with dense jungle, except where it has been cleared for mining-operations and a small amount of cultivation. Mining villages are scattered throughout the valley, the chief towns being Kampar, Batu Gajah, Lahat and Ipoh, the latter being the center of the mining-operations. An ideal section of the main geological features of the Kinta valley is given in Fig. 2. The valley is composed of a highly crystalline limestone, usually white in color, sometimes gray; in fact, it may be called marble. It is always highly inclined and often contorted, and in some places is interbedded with shale. On the east side of the valley, near its contact with the granite, it forms a remarkable series of limestone cliffs, which rise in some cases as high as 2,000 ft. above the level of the limestone in the valley. It is non-fossiliferous, and its geo-

Sep 1, 1906

(The following -list, contains the navies of those members of the Institute of whose connection with military service we have only recently become acquainted; it also includes the names of a few who have recently been promoted or transferred. A com-plete list was published in the Year Book, issued as a supplement of the Bulletin for March, 1918.) ADDICKS, LAWRENCE, Naval Consulting Board. ALINE, P. A., Camp Lewis. BARCUS, WALTER .J. E., Captain, Ordnance Department. BAUSH, JOHN R., Private, 1st Army Headquarters Regiment, Co. M. BENNETT, A. F., Lieutenant. BILLINGSLEY, PAUL, Engineer Officer, Aviation Section, Signal Officers' Reserve Corps. BOOTH, L. E., Ordnance Department. BROWN, JAMES F., 2d, 1st Lieutenant, Ordnance Reserve Corps, A. E. F.

Jan 4, 1918

THE illustration below shows the design of the face of the clock to be erected as a memorial to the American engineers who gave their lives overseas in the World War. It will be placed in the tower of the library at Louvain, which has been rebuilt through contributions from America. Large clocks seldom have figures on their faces, and each hour on this one will be marked by a gold star, the four faces containing 48 stars, one for each State of the Union. Contributions toward the memorial have been received from every one of the States, and from Alaska and Hawaii as well, but additional subscriptions are invited by the Com-mittee which is arranging for the memorial.

Jan 3, 1928

By AIME AIME

ONE hundred and eighty-three A.I.M.E. members, W. S. Morris with an excellent technical program, John Suman, "oil" President of the Institute, and a Texas norther blew into Dallas for the fall meeting of the Petroleum Division at the Adolphus Hotel, Oct. 16-18. and the most successful result will give future meeting committees a high mark to equal. People were still talking of the terrific heat the week before and it was quite noticeable that with the lowered temperatures, the members were in fine fettle for the technical sessions. The total attendance on Friday noon was

Jan 1, 1941