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By GUY C. RIDDELL

THE recent purchase by an American investment trust of a substantial block of shares in a British owned Venezuelan copper operation directs attention to mining activities that have been quietly gaining momentum in that country for a number of years. We hear so much of oil work in Venezuela that attention to its metal-mining activities is in most quarters casual. In gold and copper the country has made some interesting mining records, and two of the old districts are ,digging in for a come-back. Copper Copper production centers in the state of Yaracuy. The Aroa-Cumaragua mining region has had a long and eventful history. The Aroa mine itself, 50 miles from the coast in West-Central Venezuela, was discovered in 1605. First mined in 1632, owned at one time by Simon Bolivar, it has been reopened many times and is now , the basis of substantial operations by the South American Copper Syndicate, Ltd. of London. The latter has operated the property profitably, off and on, for a number of years, paying heavy dividends on a small investment-at times over 300 per cent annually.

Jan 1, 1929

By R. M. Hardgrove

PULVERIZED coal was first used for firing cement kilns about 45 years ago, with such success that it has continued in general use. Based on cost, pulverized coal is usually the most economical fuel. In some localities natural gas or oil is cheaper, but 85.5 per cent of all cement kilns at present are fired with pulverized coal. The pulverized-coal flame is well suited to kiln conditions. Its soft, luminous nature gives it a high radiating property and the length of the flame can be readily varied to suit conditions in a kiln of any length. Ash and slag cause most of the difficulties incident to the burning of coal. In a cement kiln, however, the ash, being similar in composition to the raw mix and being deposited uniformly in the mix and clinker, occasions no difficulty as long as it remains constant in quality and quantity. Until 6 years ago almost all cement kilns using pulverized coal employed the bin system. The coal was dried and pulverized in a separate plant and delivered into a bin at the kiln. Thus the bin system requires driers, storage-type pulverizers, conveying systems, individual kiln bins, pulverized-coal feeders and primary air fans. The direct-fired system requires only a pulverizer and a blower. Fig. I shows typical plants. The first installations of direct-fired pulverizers were of the impact type but fineness of pulverization was both inadequate and variable. About 1927 a few direct-fired installations employing tube-type pulverizers were made, which were much more satisfactory. As more efficient pulverizers were developed from 1934 on, equipment for direct firing was installed at a large number of plants, until now 196 of about 900 kilns in use in the United States are direct-fired. Most of these replaced antiquated bin systems. PROCESS OF BURNING CEMENT CLINKERS The process of burning cement clinkers is fundamentally one of heat transfer. In boilers and other heat-exchange apparatus the area of the surface receiving heat from the gases is the best unit for comparing output. This seems to be equally true for kilns. The inside kiln surface is the heat-receiving surface and its area is used as the unit of kiln size in the following comparisons. Heat input is based on British thermal units in the fuel. E. G. Bailey,1 in his work on boiler-furnace heat absorption, has used the unit "B.t.u. available." This is the practical calorific power of the fuel, plus the heat in the air used for combustion. In other words, it is the heat available for useful work in the furnace or kiln. The unit of kiln output is barrels per hour. The composition of the raw mix, the percentage of water in the slurry of wet plants and hardness of burning all affect the output. These conditions, however, are hard to evaluate and probably have less effect on the output than irregularities of raw feed and clinker discharge and inexpert control of combustion. WET VS. DRY PLANTS The study presented here covers 88 plants, of which 41 are wet and 47 dry. Of

Jan 1, 1941

By H. G. Doll

As a continuation of the earlier paper on the general subject of the SP log, a more complete analysis of certain features of the SP log in shaly sands is given. The pseudo-static SP in front of shaly sands is compared, on a theoretical basis, to the static SP in front of clean sands, as a function of the respective amount of shale and sand in the formation, and of the relative resistivities of the shale, of the uncontaminated part of the sand. and of the invaded zone of the sand. As a conclusion, the advantage of using reasonably conduc. tive mud in this case is shown. The discussion is illustrated by field examples. INTRODUCTION The discussion reported in the present paper is based on a theoretical analysis, and not on experiment. The field examples, joined to the text. are shown only as qualitative illustrations of the essential results of this analysis. Although the hypotheses made in the theoretical developments may perhaps be somewhat improved, it seems, nevertheless, that the results obtained account reasonably well for the actual phenomena, and give a fair approximation of their order of magnitude. The paper contains a mathematical analysis of a tri-dimen-sional distribution of potentials and current lines. due to spontaneous electromotive forces arising at the contact of shales and free electrolytes. as a function of the geometry and of the respective resistivities of the different media involved. It is assumed, although this hypothesis is not proven, that the emf's remain the same even if the shale occurs in very thin layers or in dispersed particles. It has already been pointed out 1,2,3 that, all other conditions being the same, the deflection of the SP log in front of a shaly sand is smaller than opposite a clean sand. When the thickness and the conductivity of a clean sand are large enough. the deflection of the SP log reaches a limiting value which is equal to the "static SP" of the clean sand. It is generally convenient to take the static SP of shale as the reference value or "base line." As a consequence, and for the sake of abbreviation, the expression. "static SP of a clean sand," is often used to designate the difference between the static SP of that sand and that of the shales, which difference is a measure of the total electromotive forces involved in the chain mud sand-shale. A similar limiting value is; also observed for the SP deflec-lion opposite a thick shaly sand, but it is smaller. just as if the total electromotive force involved were smaller in that case. This limiting value has been called the "Pseudo-Static SP" of the shaly sand. The static SP of a clean sand depends on the salinity of its connate water with respect to that of the mud, and, to a certain extent. on the differential pressure which controls the electro-filtration potentials, but it does not depend on the resistivity of the sand. On the contrary. the pseudo-static SP of a shaly sand depends not only on the salinity of its connate water and on the differential pressure, but also on the percentage of shale and on the resistivities of the shale, of the uncontaminated part of the sand, and of the zone invaded by the mud filtrate. If the three resistivities above were equal, the pseudo-static SP would be proportional to the percentage of sand in the shaly sand, and its departure from the static SP of a clean sand having the same connate water would simply be proportional to the percentage of shale. In that case, the pseudo-static SP of a shaly sand containing 10 per cent of shale would he 10 per cent less than the static SP of a clean sand. When. however. the sand is. on the average. substantially more resistive than the shale. the percentage of departure of the pseudo-static SP from the static SP of a clean sand is much larger than the percentage of shale. For that reason, the peaks of the SP log opposite shaly sands are systematically of smaller amplitude when the sands are oil-bearing than when they are water-bearing, all other conditions being the same. This feature is observed even when the sand beds are thick. and even when they do not contain a large percentage of shale. All this has already been described in all earlier publication", but mostly in a qualitative way. The present paper will analyze in more detail the action of the local SP currents which are generated inside of the shaly sands, and which are responsible for the abnormally low value of the pseudo-static SP. The quantitative computations have been extended to the general case of thin interbedded layers of sand and shale, where the resistivities of the shale and sand streaks do not have the same value: they are summarized in charts giving values of the pseudo-static SP of a shaly sand as a function of the different parameters involved. DEFINITIONS The static SP of a clean sand has been defined as the potential that would exist in the mud opposite that sand, were the SP current prevented from flowing. Such an ideal condition is represented on Fig. I-A. By analogy, the pseudo-static SP of a shaly sand can be defined as the potential that would exist in the hole, if the circuit shaly sand — surrounding shales — mud column were interrupted by the insulating plugs placed at the boundaries

Jan 1, 1950

By Omar A. Muhtadi

Experimental statistical designs were used at Zortman Mining Company's, Zortman, Montana, heap-leach operation to establish functional relationships between key operating parameters and gold/silver recoveries. Zinc feed rate, lead feed rate, and vacuum (CFM/gpm) account for 64% and 67% of the attainable gold and silver recoveries, respectively. Surface response graphs of the resulting polynomials were plotted. These graphs were used to optimize Zortman's Merrill-Crowe precipitation process.

Jan 1, 1984

By J. Brian Eby

The Gulf Coast of southern Louisiana during the year of 1940 was subjected to an extensive exploration and development campaign, as a result of which 16 oil fields and about 38 new producing sands were found. Although this record of discovery appears in keeping with the rate of 1939 actually in amount of new proven reserves, it may fall short of that of the previous year. Only five or six of the discoveries rated as first-class or important fields at the close of the year. The most prominent new fields opened during the year were Neale field in Beaure-gard Parish, the West Cote Blanche field in St. Mary Parish, the Stella field and the West Bay field in Plaquemines Parish, and the Lake Salvador field in St. Charles Parish. There were many important oil-sand discoveries in proven fields, such as in the Bayou Perot field, the Golden Meadows field, the Iowa field, West Lake Verrett field, and the Venice field. During the year, 1047 weUs were drilled in southern Louisiana, of which 768 were completed as oil-producing wells, 17 as gas wells and 262 as dry holes. The Neale field in northwest Beauregard Parish is considered one of the most important discoveries of the year. The f~eld centers around the north half of sec. 26, 'Y.3 S., R.I I W., just north of the town of Neale. It was discovered by the Atlantic Refining Co., using reflection seismograph to locate the structure. Production was found in the second well drilled in the Wilcox sand on the downthrown side of a fault. The structure is known as the "Tepetate" type, being similar to that of the well-known Tepetate field. There were 12 oil wells and 3 dry holes drilled during the year. The Wilcox sand in this field occurs between 8350 and 8400 ft. and averages 30 ft. in thickness. The West Cote Blanche Bay field, in West Cote Blanche Bay, St. Mary Parish, is a 1940 discovery by the Texas Company, credited to reflection seismograph exploration. The oil is from two sands occurring at 3110 to 3140 ft. and from 4950 to 5020 it. Four wells were drilled during the year, three oil wells and one dry hole. The deepest hole drilled reached 9491 ft. without encountering salt or dome material. In Plaquemines Parish, south of New Orleans, the California company has a new field known as the Stella field. The sand was found at a depth of 7485 ft., and 5 ft. of perforations made a well capable of producing 486 bbl. of oil in 24 hr. through a 9.is-in. choke. The oil is 42" gravity. The discovery well was drilled to a total depth of 10,258 ft. and other producing sands were indicated. A good field appears assured, although only one well was completed within the year. The Lake Salvador field, in the center of Lake Salvador, St. Charles Parish, gives promise of being one of the most important discoveries of the year. The discovery well was perforated at 9775 to 9800 ft. making 850 bbl. of 33.7° gravity oil daily through a 1/4-in. choke. Three wells were completed in 1940 but few details have as yet been made available.he Gulf Oil Corporation apparently has a good field in its wildcat discovery in West Bay, Plaquemines Parish. This well found

Jan 1, 1941

By J. Brian Eby

The Gulf Coast of southern Louisiana during the year of 1940 was subjected to an extensive exploration and development campaign, as a result of which 16 oil fields and about 38 new producing sands were found. Although this record of discovery appears in keeping with the rate of 1939 actually in amount of new proven reserves, it may fall short of that of the previous year. Only five or six of the discoveries rated as first-class or important fields at the close of the year. The most prominent new fields opened during the year were Neale field in Beaure-gard Parish, the West Cote Blanche field in St. Mary Parish, the Stella field and the West Bay field in Plaquemines Parish, and the Lake Salvador field in St. Charles Parish. There were many important oil-sand discoveries in proven fields, such as in the Bayou Perot field, the Golden Meadows field, the Iowa field, West Lake Verrett field, and the Venice field. During the year, 1047 weUs were drilled in southern Louisiana, of which 768 were completed as oil-producing wells, 17 as gas wells and 262 as dry holes. The Neale field in northwest Beauregard Parish is considered one of the most important discoveries of the year. The f~eld centers around the north half of sec. 26, 'Y.3 S., R.I I W., just north of the town of Neale. It was discovered by the Atlantic Refining Co., using reflection seismograph to locate the structure. Production was found in the second well drilled in the Wilcox sand on the downthrown side of a fault. The structure is known as the "Tepetate" type, being similar to that of the well-known Tepetate field. There were 12 oil wells and 3 dry holes drilled during the year. The Wilcox sand in this field occurs between 8350 and 8400 ft. and averages 30 ft. in thickness. The West Cote Blanche Bay field, in West Cote Blanche Bay, St. Mary Parish, is a 1940 discovery by the Texas Company, credited to reflection seismograph exploration. The oil is from two sands occurring at 3110 to 3140 ft. and from 4950 to 5020 it. Four wells were drilled during the year, three oil wells and one dry hole. The deepest hole drilled reached 9491 ft. without encountering salt or dome material. In Plaquemines Parish, south of New Orleans, the California company has a new field known as the Stella field. The sand was found at a depth of 7485 ft., and 5 ft. of perforations made a well capable of producing 486 bbl. of oil in 24 hr. through a 9.is-in. choke. The oil is 42" gravity. The discovery well was drilled to a total depth of 10,258 ft. and other producing sands were indicated. A good field appears assured, although only one well was completed within the year. The Lake Salvador field, in the center of Lake Salvador, St. Charles Parish, gives promise of being one of the most important discoveries of the year. The discovery well was perforated at 9775 to 9800 ft. making 850 bbl. of 33.7° gravity oil daily through a 1/4-in. choke. Three wells were completed in 1940 but few details have as yet been made available.he Gulf Oil Corporation apparently has a good field in its wildcat discovery in West Bay, Plaquemines Parish. This well found

Jan 1, 1941

By R. J. Brison, O. F. Tangel

The development of a new method of mineral separation was sponsored by the International Salt Company, which requested Battelle Institute to investigate means for improving the quality and appearance of rock salt from the Company's Detroit mine. Although developed specifically for removing impurities from rock salt, the general method may be applicable to other separation problems. The principal impurities in rock salt from the Detroit mine are dolomite and anhydrite which represent 2 to 5 pct of the weight of the mined salt. In the size range from 1/4 to M in. (the range of primary interest in this project) the impurities are only partially liberated from the halite in normal production. Further size reduction to improve the liberation of impurities is not practicable in view of the market requirements for the coarse grades of rock salt. Laboratory separations in heavy liquids showed that, to improve the quality and appearance of the rock salt substantially, it would be necessary to remove not only free gangue particles but also a large proportion of the locked-in particles. Because rock salt is an inexpensive commodity, a low-cost process was required. Gravity methods were, of course, considered. The heavy-liquid separations indicated that a split at an effective specific gravity of 2.2 to 2.3 would be required. (The specific gravity of pure halite is 2.16.) Heavy-media separation was investigated but had the disadvantages that it was necessary both to operate with saturated brine and to dry the cleaned salt, and that the cleaned salt was darkened by the magnetite medium. Air tabling was tried but did not give the desired separation. It soon became apparent that established methods would not provide a satisfactory solution and work was undertaken on the development of a new process to solve the problem. PROCESS DEVELOPMENT Preliminary Experiments: At the start of the investigation, an analysis of the problem indicated that the diathermacy of rock salt—that is, its ability to transmit radiant heat—might form the basis for an efficient separation process. Under this theory, the impurities might be selectively heated by radiant heat. The particles could then be fed over a belt coated with a heat-sensitive substance so that the warm impure particles would adhere preferentially to the coating. After the initial experiments, made by heating the rock salt with an infrared lamp and separating the product on small sheets of resin-coated rubber, proved encouraging, a small continuous separation unit was set up. This comprised 1) a simple heating unit consisting of a vibrating feeder covered with aluminum foil and an infrared lamp mounted above the feeder and 2) a separation belt 6 in. wide and 36 in. long. A sketch of the device is shown in Fig. 1. Results with this apparatus confirmed the fact that a good separation was possible. It was apparent, however, that a considerable amount of experimental work would be needed to develop the scheme to a practical and economical process. The Process: Basically, the process consists of two main steps: 1) selective heating by radiation and 2) separation of the heated particles on a heat-sensitive surface. Because neither of these steps had previously been utilized commercially in mineral processing, it was necessary to do basic research on both aspects. Factors studied in the investigation included type of heat source, design of heating unit, design of separation belt, selection of heat-sensitive coating, removal of heated particles from the belt, contact between particles and coating, and maintenance of the heat-sensitive surface. Part of the experimental work was carried out on a small-scale unit consisting of the 36x6 in. belt and auxiliary apparatus, and part on a larger unit. For simplicity, discussion of work on both of these units is grouped together. SELECTIVE HEATING Radiant-Heat Source: The essential requirements for a radiant-heat source were 1) that the radiant heat be in a wave length range which is effectively absorbed by the impurities but not absorbed appreciably by the rock salt and 2) that it be dependable, practical, and economical. Selection of a heat source of suitable wave length range was one of the first considerations. It is well known that pure halite is highly transparent to radiant energy in wave lengths from 0.3 to 13 microns. However, the available data on infrared transmission by dolomite and anhydrite, particularly in the range below two microns, were not complete enough to serve as a reliable basis for selection of a heat source. Although it may have been possible to obtain sufficient data on infrared transmission and absorption to enable one to select the best heat source, a more direct procedure was used. This consisted simply of exposing the crude rock salt to each of several types of radiant-heat source on the small continuous separation device. The heat sources investigated, approximate source temperature used, and calculated wave length of maximum radiation are tabulated in Table I. Of the two types of tungsten-filament lamps investigated, both the short wave length photoflood lamps and the longer wave length infrared lamps were satisfactory from the standpoint of selectivity

Jan 1, 1961

By R. M. Hardgrove

PULVERIZED coal was first used for firing cement kilns about 45 years ago, with such success that it has continued in general use. Based on cost, pulverized coal is usually the most economical fuel. In some localities natural gas or oil is cheaper, but 85.5 per cent of all cement kilns at present are fired with pulverized coal. The pulverized-coal flame is well suited to kiln conditions. Its soft, luminous nature gives it a high radiating property and the length of the flame can be readily varied to suit conditions in a kiln of any length. Ash and slag cause most of the difficulties incident to the burning of coal. In a cement kiln, however, the ash, being similar in composition to the raw mix and being deposited uniformly in the mix and clinker, occasions no difficulty as long as it remains constant in quality and quantity. Until 6 years ago almost all cement kilns using pulverized coal employed the bin system. The coal was dried and pulverized in a separate plant and delivered into a bin at the kiln. Thus the bin system requires driers, storage-type pulverizers, conveying systems, individual kiln bins, pulverized-coal feeders and primary air fans. The direct-fired system requires only a pulverizer and a blower. Fig. I shows typical plants. The first installations of direct-fired pulverizers were of the impact type but fineness of pulverization was both inadequate and variable. About 1927 a few direct-fired installations employing tube-type pulverizers were made, which were much more satisfactory. As more efficient pulverizers were developed from 1934 on, equipment for direct firing was installed at a large number of plants, until now 196 of about 900 kilns in use in the United States are direct-fired. Most of these replaced antiquated bin systems. PROCESS OF BURNING CEMENT CLINKERS The process of burning cement clinkers is fundamentally one of heat transfer. In boilers and other heat-exchange apparatus the area of the surface receiving heat from the gases is the best unit for comparing output. This seems to be equally true for kilns. The inside kiln surface is the heat-receiving surface and its area is used as the unit of kiln size in the following comparisons. Heat input is based on British thermal units in the fuel. E. G. Bailey,1 in his work on boiler-furnace heat absorption, has used the unit "B.t.u. available." This is the practical calorific power of the fuel, plus the heat in the air used for combustion. In other words, it is the heat available for useful work in the furnace or kiln. The unit of kiln output is barrels per hour. The composition of the raw mix, the percentage of water in the slurry of wet plants and hardness of burning all affect the output. These conditions, however, are hard to evaluate and probably have less effect on the output than irregularities of raw feed and clinker discharge and inexpert control of combustion. WET VS. DRY PLANTS The study presented here covers 88 plants, of which 41 are wet and 47 dry. Of

Jan 1, 1941

By Noel Cunningham

MANY excellent descriptions of the mills of the, Porcupine district have been written, but no discussion exclusively devoted to the metallurgical technology has been given. These notes are intended to cover this feature briefly. They are based upon 2 ½ years' mill operation in the district-i.e., practically since the beginning of metallurgical operations. Character of the Porcupine Ore.-There is no oxidized ore in the district, the surface having been deeply planed by glacial action in recent geologic time. The precious-metal content is about in the proportion of 85 of gold to 15? of silver by weight; hence, the silver is practically negligible. There are two classes of Porcupine ore, having very different characteristics; these will be referred to throughout this paper as Class A and Class B. Class A ore is a pure quartz with inclusions of schist. Generally it is heavily fractured .and breaks down readily to sharp, hard grains, about minus 10 plus 20 mesh, requiring further comminution to release the gold. It carries very little pyrite; the gold is entirely free and apt to be coarse, but often spongy, going into solution readily on that account. This gold is 60 per cent. to 85 per cent. free milling, depending on the grade of ore. Class B ore is an iron silicate schist, strongly laminated, carrying 4 to 5 per cent. pyrite; its specific gravity is 2.8 to 3.0, depending upon the amount of mineralization. In breaking the ore in the mine, generally over 25 per cent. of material through a ½ -in. ring is made; the ore readily breaks down in milling and makes a comparatively large amount of non-crystalline slime; owing to its high specific gravity, however, it is quick settling.' In my opinion, the gold in this ore is free, but so finely divided that it will neither pan nor amalgamate; it appears to be disseminated through the rock and not chiefly associated with the pyrite. Veins of Class A ore occur with or without side walls of Class B, and veins of Class B occur unassociated with Class A; more often the veins are closely banded, Class A and Class B alternating, generally with Class B in excess. Both classes of ore are more-or less blocky at times, and with ref¬erence to Class B this is indicative or low gold content.

Jan 3, 1915

By L. W. Bahney

MANY methods for the determination of gold or silver, or both, in cyanide solutions have been published, which with care in manipulation, and modification in some cases, will give results that are satisfactory. It is possible to classify or group these methods as follows: 1. Evaporating the solution in a porcelain or agate-ware dish containing litharge,1 or in a "boat" made of lead foil. 2. Forming a lead sponge containing the precious metals by means of zinc shavings,2 zinc dust,3 or a piece of aluminum.4 3. Decomposing the cyanide solution with an acid and precipitating the precious metals by the use of one or a combination of some of the following: Copper sulphate,5 sodium sulphite,6 hydrogen sulphide,7 cement copper.8 4. Precipitating the silver by zinc dust held in a Hooch crucible and determination with a standard solution of sulphocyanate.9 5. Electrolysis.10 6. Colorimetry.11

Jan 2, 1915

By Harry C. Wiess

PETROLEUM has come to be one of the most important and essential of the mineral re- sources of the nation. It is the most advantageous source of mineral fuels and of lubricants, and as such it has provided in large measure for the phenomenal development in our modern means of travel and in the facilities for transportation by land, sea, and air. Without it the remark- ably rapid industrial and social progress in our country during the past thirty years could not have occurred. In view of its important place and the fact that petroleum is irreplaceable and existent in limited quantities in nature, its conservation is essential.

Jan 1, 1939

By J. B. Morrow

WITH numerous plans under consideration for coal classification, and with the advent of the Bituminous Coal Code, the intelligent sam-pling of coal has become increasingly important. To us it is rather significant that there have been very few fundamental studies of coal sampling in American technical literature since those of E. G. Bailey, which appeared in the Journal of Industrial and Engineering Chemistry in March, 1909. He covered the subject up to that time so thoroughly and in such an excellent manner that perhaps many other later students have felt that they could add very little to his findings. The recent studies of the British Engineering Standards Association have indicated the possibility of a somewhat different interpretation of Bailey's results, permitting the taking of smaller samples, and perhaps it will now be helpful to reopen this question. C. W. H. Holmes, in an informative series of articles on coal sampling recently published in Colliery Engineering, makes two rather interesting statements, as follows: It is scarcely surprising to find a lack of interest and knowledge regarding the sampling of coal not only in the mining industry itself but also among consumers of industrial fuel: at its best coal sampling is a dirty business, regarded as a nuisance and an expense by the commercial man, and usually as a nuisance and nothing else by the chemist. The writer can conceive only two classes of people who have never experienced any difficulty in obtaining representative samples of coal from wagons; those who have never tried to, and those who have never had the necessity or desire to check the accuracy of their work. The primary purpose of this paper is to present some tabulated data of the more significant results of a sampling investigation undertaken during the last four years to obtain certain fundamental data on the variables connected with coal sampling and to point out that often assumptions have been made that are not in accordance with the facts. One of the standard sampling methods states:

Jan 1, 1935

By Philip Bucky

THE term "longwall mining" is best known to coal men, although modifications of the method are continually being used in other fields. Longwall mining is of interest today because it makes for greater mecha-nization and better supervision at the working face, and therefore lower production costs and increased safety. It is an approach to the factory system of production, the high efficiency of which as compared to that in mines is well known. There is available an accumulation of experience regarding this work but coordination of experience is lacking and this series of experiments was undertaken to help serve this purpose. Model experiments were used for reasons of safety, cost and time, and because it has been previously shown1,2,3 that a scalar model built of the same material as the prototype will behave in a manner similar to that of the prototype, with time effects the same, if the effective weight of the model is increased in the same proportion as its linear dimensions are decreased. This is accomplished by substituting a centrifugal for the gravitational field; i.e., placing the model in a centrifuge and controlling the strength of the centrifugal field by varying the rate of rotation. Many factors affect the behavior of the geologic material overlying a bed, therefore results and conclusions contained in this paper apply only to the conditions presented herein.

Jan 1, 1938

By James A. Roberson

THE mechanical behavior of molybdenum has become a matter of considerable interest in recent years because it has a reasonably high strength at high temperatures. Various aspects of its fatigue behavior have been investigated previously,1-3 and the results can be summarized as follows. Recrys-tallized molybdenum exhibits a fatigue limit which decreases continuously with increasing temperature. The ratio of fatigue-limit stress to ultimate tensile stress is high (0.6 to 0.8) and reasonably constant. The present work was undertaken to determine the effect of variations in environment on the fatigue of molybdenum stressed in fully reversed axial tension compression. In order to provide a basis to which these data could be compared, a complementary series of fatigue tests were made in vacuum. All of the specimens used were made from one mill lot of unalloyed molybdenum which had been vacuum-arc melted, worked down to 1-in.-diam bar, re-crystallized, then warm-worked to 5/8 in. diam. The interstitial content by weight was as follows: C—0.022 pet, 02-0.0026 pet, Hz-0.0001 pet, and N20.0002 pct. The average grain diameter in the transverse direction was about 0.035 mm, and the average grain length was about 0.15 mm. Typical tensile-test data are shown in Table I. None of the specimens tested exhibited an upper yield point.

Jan 1, 1965

By O. A. Kiehn, C. A. Born, F. N. Bender

Development of the flotation reagent scheme at Climax Molybdenum Company's mine at Climax Colorado is reviewed. Features of the mineralogy, milling practice and background of reagent changes are outlined. Special attention is given to the hitherto unpublished details of the application of depressants for copper and lead impurities. The present rougher flotation reagent scheme utilizes a neutral hydrocarbon oil, low in unsaturates and wax, as collector with a sulfated coconut oil emulsifier and pine oil frother. Lime and sodium silicate are used as rougher conditioning and slime dispersant agents. Chalcopyrite and galena impurities are depressed in both rougher and cleaner plants by stage addition of Nokes reagent and sodium cyanide to yield a metallurgical grade molybdenite concentrate containing greater than 90% molybdenite and less than 0.5%, 0.1% and 0.05% iron, copper and lead impurities, respectively.

Jan 1, 1976

By Ivan Simon, R. K. McConnell

Anticipating the availability of tiltmeters suitable for use in boreholes, this article proposes a method of using one or more of these meters to determine in situ stress distribution before and after mining operations. Several ways of using relief techniques to measure in situ stresses in rocks have been developed. These techniques, summarized by Merrill,1 involve measuring deformations which take place when a specimen of rock is wholly or partially isolated from the stress field in the surrounding rock. Measurements of rock deformation caused by stress relief from mining operations can, in principle, also be used to estimate in situ stress distributions. Müller2 has mentioned experiments being carried on in Austria with a "deformation indicator" to determine the tilting of holes drilled before a mine opening is made. Similar work using borehole extensometers has been reported by Potts? and Duvall4 has called attention to the possible use of tiltmeters in making these measurements. Considerable attention is now being paid to the use of tiltmeters in detecting rock deformation associated with fault movements, earthquakes, earth tides, etc. The instruments used for these measurements have usually been of the mercury tube, water tube, or quartz fiber type, but because of their large size, and/or fragile nature, such instruments would not be suitable for use in mining stress measurements. Recent instrumentation developments, however, give promise that rugged, sensitive tiltmeters small enough for use in boreholes may soon be available.' In anticipation of these developments, this article presents a number of calculations of the possibility of using one or more tiltmeters emplaced in a drill hole prior to mining operations to determine the in situ stress distribution both before and after a mining operation. Consider point p (x, z) near a tunnel of radius a

Jan 1, 1969

By Lawrence S. Darken

STAFF: Editor, Gerhord Derge Cornegie Institute of Technology Schenley Pork Pittsburgh 13, Pa. Editorial Assistant, M. A. Redmerski Production Editor, Otto T. Johnson THE METALLURGICAL SOCIETY: J. S. Smart, Jr., President; C. C. Long, Past-President; K. L. Fetters, Vice President; T. D. Jones, Treasurer; R. W. Shearman, Secretary. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: C. L. McCabe, Chairman; H. L. Bishop, K. L. Fetters, J. J. Harwood, W. A. Krivsky, F. C. Longenberg, R. E. Lund, W. 0. Philbrook, L. L. Seigle, R. L. Smith, and F. L. Vogal. Review and selection of manuscripts is under the supervision of the following Publications Committees: Extractive Metallurgy Division: C. L. McCabe, Chairman; R. E. Lund, Vice-chairman; D. H. Baker, Jr., W. A. Krivsky, R. A. Lewis, Paul Qusneau, A. S. Russell, R, E. Shinkoskey, W. W. Stephens, and M. E. Wadsworth. Institute of Metals Division: L. L.Seigle, Chair-man, P. A. Back, J. J. Backer, l.l. Bessen, J. 0. Betterton, Jr., J. 8. Clark, R. S. Davis, A. E. Dwight, R. W. Fountain, R. B. Gordon, C. D. Graham, Jr., R. W. Guard, J. C. Gurland, E. L. Harmon, J. J. Hager, A. A. Hendrickson, M. Harmon, J. N. Hobstatter, H. H. Johnson, Jr., H. 5. Kolish, R. R. Nash, T. N. Rhodin, R. H. Richman, W. Rostokar, P. G. Shawmon, C. W. Spencer, L. Slifkin, J. K. Stanley, C. D. Starr, R. Steinitz, and H. C. Stumpf. Iron and Steel Division: H. L. Bishop, Chairman; 2. E. Boni, F. C. Langenberg, J. B. Wagstaff, and T. V. Wainwright. Published bimonthly by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., 29 West 39th Street, New York 18, N. Y. Telephone: PEnnsylvania 6-9220. Subscription PetroleumEngineers,$30 per year for non-AIME members in United States and North, South, and Central America; 332, foreign; $5 for AlME members. Single copies, $4.00, single copies foreign, $5.00. The AlME is not responsible for any statement mode or opinion expressed in its publications . . . Copyright 1%1 by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. . . . Registered cable address; AIME New York ..Indexed in Engineering Index, Industrial Arts Index, and Chemical Abstracts.. .Second class postage paid at New York, N. Y., and Ann Arbor, Mich. Volume 221, Number 4.

Jan 1, 1962

By Frederick Prime

In this supplementary list no titles to which an * is prefixed have been seen by the compiler; and he will be most thankfu1 to have any omissions or inaccuracies in the list sent to him to be published as a second supplement in the next volume of the Transactions. The author is indebted to Messrs. Robert Clarke, of Cincinnati; Thomas Macfarland, of Towanda; Professor F. W. Simonds, of Chapel Hill; and Professor J. J. Stevenson, of New York, for valuable assistance. Cedar Point IRON Company, Baltimore, July 31st, 1880. Alabama. Geological Survey of Alabama. Report of Progress for 1877 and 1878; by Eugene A. Smith, State Geologist. Montgomery, 1879. 8vo., 139 pp., and 4 maps.

Jan 1, 1880

By M. D. Cooper

FOr the purpose of obtaining some first-hand data in regard to the shooting clown of coal in bituminous 'nines, it was the writer's good fortune to be employed as a shot-firer for almost one year. In all, 6,020 shots were fired by him during this period. All of the work was clone in what is known as the South Main section of the No. 2 Mine of the Ellsworth Collieries Co., Ellsworth, Pa., a subsidiary of the Lackawanna Steel Co. Position of Shot-firing in the Cycle of Operations The established practice of the Ellsworth Collieries Co. calls first for the undercutting of the coal by electric chain machines across the face of the entry or room. This is followed by replacing any posts removed by the machine-runners, or the setting of new posts or timber, as may be required. After this has been done the machine cuttings are loaded into cars. Then the coal is spragged, and a shot hole drilled to the depth of the undercut. Next in order, the shot-firer loads the hole and fires the charge. The working place is then cleaned up, timbered if necessary, the sides and face squared up, and loose material taken down. The face is again ready to be undercut.

Jan 1, 1917

By Thomas L. Wright

Exploration activities were maintained at a high level throughout 1966. Numerous significant discoveries and developments in which geologists played an important part were announced. Although the complete results of exploration activities carried out during the year by private companies have not been announced, the following are among the more important developments that have been made public knowledge. In the western states, exploration for practically all of the metals continued at a high rate. Substantially increased interest in uranium occurred this year, and it is felt by many that a real boom in the demand for uranium may come about in the near future. The reasons have been the more rapid acceptance of atomic power than had been anticipated, and that uranium producers can now sell their product to private interests and even foreign countries. A tremendous demand for uranium is anticipated by many, and this has rekindled exploration activity. On the Colorado Plateau, in Wyoming, and in the area around Grants, N. M., a number of companies have undertaken uranium exploration programs, among which are Kerr-McGee, Homestake, Anaconda and Utah Construction. A new uranium orebody in Texas was brought into production early in 1966 by Susquehanna Western.

Jan 2, 1967