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By Shiou-Chuan Sun

THIS paper presents the design and operation of a frothmeter capable of measuring the frothing characteristics of pine oils and other frothing reagents. The experimental data show that the frothability of pine oil is governed by: 1-rate of aeration, 2-time of aeration, 3-height of liquid column, 4-chemical composition of pine oil, 5-pH value of solution, 6-temperature of, solution, and 7-concentration of pine oil in solution. The effect of mineral particles on the behavior of froth also was studied, and the results can be found in a separate paper.1 The results also show that the relative frothabilities of pine oils in the frothmeter generally correlate with those in actual flotation, provided that other factors are kept constant. In addition to pine oils, the other well-established flotation frothers were tested, and the results are included. In this paper, compressed air frothing is the frothing process performed by means of purified compressed air, whereas sucked air frothing is the frothing process accomplished by purified air sucked into the glass cylinder by a vacuum system. The term vacuum frothing denotes that froth was formed by degassing of the air-saturated liquid under a closed vacuum system. Apparatus The frothmeter, shown in Fig. 1, is capable of reproducibly measuring the volume and persistence of froth as well as the volume of air bubbles entrapped in the liquid and is capable of being used for compressed air frothing, sucked air frothing, and vacuum frothing. Fig. la shows that for compressed air frothing, the apparatus consists of an airflow regulating system, 1-3; a purifying and drying system, 4-8; a standardized flowmeter to measure the rate of airflow from zero to 500 cc per sec, 9; and a graduated glass cylinder, 13; equipped with an air regulating stopcock, 10; an air chamber, 11; and a fritted glass disk to produce froth, 12. The fritted glass disk, 5 cm in diam and 0.3 cm thick, has an average pore diameter of 85 to 145 microns. The pyrex glass cylinder has a uniform ID of 5.588 cm and an effective height of 63 cm. The inside cross-sectional area of the glass cylinder was calculated to be 24.53 sq cm, or 3.8 sq in. For sucked air frothing, Fig. lb shows that the apparatus for compressed air frothing is used again, with the following modifications: 1-compressed air and its regulating system, 1-3, are eliminated; and 2-a vacuum system, 16, equipped with a vapor trap, 15, and a vacuum manometer, 17, is added. The vacuum system can be .either a water aspirator or a laboratory vacuum pump. Any desired rate of airflow can be drawn into the glass cylinder, 13, by adjusting the opening of the air regulating stopcock, 10. The sucked air stream is cleaned by the purifing and drying system, 4-8, before entering the glass cylinder, 13. When this setup is used for vacuum frothing, the air regulating stopcock is closed. The frothmeter has been used for almost 3 years and has proved to give reproducible results, as illustrated in Table I. With a magnifying glass and suitable illumination, the frothmeter also can be used to study the attachment of air bubbles to coarse mineral particles.2 Experimental Procedures Except where otherwise stated, the data presented were established by means of the compressed air method. The volume and persistence of froth were recorded respectively at the end of 4 and 6 min of aeration at a constant rate of airflow of 29.3 cc per sec which is equivalent to 71.6 cc per sq cm per min, or 462.6 cc per sq in. per min. The aqueous solution for each test, containing 1000 cc of distilled water and 19.2 ± 0.5 mg frothing reagent, was adjusted to a pH of 6.9 ± 0.2. The volume of froth is expressed as cubic centimeter per square centimeter and is equivalent to the height of the froth column (the distance between the bottom and the meniscus of the froth). The volume of froth was obtained by multiplying the height of froth by the cross-sectional area of the glass cylinder, 24.53 sq cm. Before each test, the glass cylinder, 13, was cleaned thoroughly with jets of tap water, ethyl alcohol, tap water, cleaning solution, tap water, and finally distilled water. The cylinder with stopcock,

Jan 1, 1952

PRESIDENT HERBERT HOOVER, STANFORD UNIVERSITY; CAL. PAST PRESIDENTS SIDNEY J. JENNINGS NEW YORK, N. Y. HORACE V. WINCHELL MINNEAPOLIS, MINN. FIRST VICE-PRESIDENT EDWIN LUDLOW, NEW YORK, N. Y. TREASURER GEORGE D. BARRON NEW YORK, N. Y.

Jan 1, 1923

Peculiarities of Quartz Distribution in Zinc Flotation Products and their Influence to Mineral Processing

Sep 13, 2010

By Robert B. Parsons

"In all likelihood, Canada's mining industry would be adversely affected by corporate tax reform proposals actively being considered by the Department of Finance in Ottawa. When the next set of proposals for lax reform is released later this year as promised by Finance, the mining industry had better be prepared 10 take a hard look.IntroductionTwo federal budgets ago, in May 1985, Finance Minister Wilson tabled budget papers that were more massive in terms of volume than most federal budgets. Buried in this mass of documentation is a discussion paper entitled ""The Corporate Income Tax System-A Direction For Change"". When the discussion paper was tabled over one year ago, reaction from the business sector was almost nonexistent. By and large, the paper was regarded as nothing more than one more federal publication of mild academic interest.But, recent events suggest that this discussion paper for corporate tax reform could be the cornerstone for a series of changes to the tax laws which would have more profound and widespread effects for all sectors of the economy than any reform since 1971 . No industry in Canada can afford to ignore the movement afoot in Ottawa for corporate tax reform."

Jan 1, 1986

By K. P. Wang

Under the Communist regime marked industrial progress has been achieved on the China mainland. Within a decade, the country has been transformed from an economy primarily agricultural to one bristling with industrial possibilities. The industrial capacity of Communist China is beginning to approach that of Japan and will probably surpass it by 1962, the last year of the Second Five-Year Plan. The slogan already is Beat the United Kingdom by 1972, a goal which most observers feel will be achieved ahead of schedule. During the early years of the industrialization program in Communist China, emphasis has been placed on basic goods; hence additional time will be needed to make large quantities of the more complicated products. However, regardless of the current stage of industrial development, it is apparent that the necessary forward momentum has been created. The many capital construction projects being brought into production and the additional projects being initiated confirm this observation. The accuracy of Communist China's industrial statistics can be questioned, but their order of magnitude is clear. To properly evaluate the industrial capability of the country, differentiation must be made between the absolute quantities that reflect overall strength and the per capita quantities that reflect living standards. While Communist China is well on the road to becoming a world power, its living standards will remain below European levels for many years to come.

Jan 8, 1960

By Y. M. Zhao

The separating performance of a pilot dry beneficiation system using a gas-solid fluidized bed was investigated with coal from South Africa. The coal used for the study has a low inherent moisture content, a moderate ash content, a moderate volatile content, a low sulphur content and a high calorific value. Its washability is moderate. Experimental results show that the separating quality of the fluidized bed drops gradually as the feed-coal particle size decreases. The probable error, E, values for 50?25mm, 25?13 mm and 13?6 mm coals were 0.04 g/cm3, 0.06 g/cm3 and 0.09 g/cm3, respectively. The cause of the differences in separating characteristics was analysed by particle dynamics and numerical modelling. Furthermore, the pilot fluidized bed was employed to separate 50-6mm coal. In this experiment the coal ash content was reduced from 23.74% to 11.79%, with a probable error, E, value of 0.07 g/cm3and a recovery efficiency of 98.26%. This indicates that the fluidized bed is applicable to the separation of coal from South Africa and has good separating performance and wide applicability. Keywords: feed-coal particle size; gas-solid fluidized bed; dry coal beneficiation; numerical simulation.

Jan 1, 2010

By B P. Scott

Podsol soil horizons developed on Pleistocene glacial sediments overlying the Coronation Mine orebody were analyzed for copper and zinc spectro-photometrically, using biquinoline-isoamyl alcohol and dithizone carbon tetrachloride reagents. Copper and zinc are concentrated in the A. and C horizons, whereas the A1, A2 and B horizons are leached. Of economic significance is the fact that the C horizon contains a copper anomaly, in excess of 100 times back-ground, directly over the orebody. Due to the erratic distribution of high copper concentrations in the Ao horizon with respect to the orebody, that horizon is not considered as a reliable prospecting datum. U NDER certain conditions, metallic ore deposits are accompanied by primary halos of trace elements in unweathered rock surrounding the orebodies or by secondary halos in weathered rock, alluvium, soil, or vegetation above or near the mineralized zones. Where such halos occur, chemical analysis, as applied to the detection of trace elements, is a valuable prospecting aid, permitting the detection of mineralization of possible economic value.

Jan 1, 1965

By David C. Oyler, William P. Diamond

Three long horizontal holes were drilled from a directionally drilled sur¬face hole at the Emerald Mine near Waynesburg, Pa. The purpose was to adapt the technique of directional drilling for use in draining methane from coalbeds. A 504-m (1,652-ft) long, 76-mm (3-in) diam¬eter, circular arc pilot hole was drilled, using a downhole mud motor, to enter the Pittsburgh coalbed at a verti¬cal depth of 305 m (1,000 ft). The hole was reamed to 222 mm (8-3/4 in) and was cased to a measured depth of 486 m (1,595 ft). Three 76-mm (3-in) diameter horizontal drainage holes were then drilled, totaling 2,909 m (9,544 ft) of horizontal hole. Improvements in drilling methods increased the average drilling rate from 20.4 m (67 ft) to 64.9 m (213 ft) per day. The cost of drilling the directional and horizontal holes (using a Government-owned drill rig) was $1,169,530, a figure inflated by inexperience and by delays caused by lost-circulation problems and fishing operations. An estimated total drilling cost of $960,000 (including rental of a drill rig) for an improved system, was determined by a detailed cost analysis. Initial gas and water production from November 1979 through May 1980 was low because of caving of the horizontal holes drilled in shale near the bottom of the casing.

Jan 1, 1982

By J. E. Berg

This paper3 describing the mining methods at the Page mine operated by the Federal Mining & Smelting Co., is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The Page mine is the most westerly of the producing lead-silver-zinc mines in the Coeur d'Alene mining district of Idaho, being situated 5 miles west of the city of Kellogg and at an elevation of 2,677 feet above sea level. It may be classed as one of the new active producers, of the district and owes its present activity largely to the development of floatation.

Jan 1, 1930

By Shane Yanagisawa

The Mineral Creek Diversion Project is at the Asarco Ray Mine Complex, about128 km (80 miles) east of Phoenix, Arizona. The new tunnel will intercept the waters of Mineral Creek about 2,134 m (7,000 ft) upstream from an existing tunnel. The 5.74 m(18.83 ft) hard rock TBM will break into the old tunnel about 2,162 m (7,090 ft) in from the old portal after mining 3,888 m (12,753 ft). The TBM will mine through a series of igneous and metamorphic formations including volcanic tuff, soft volcanic ash, massive diabase, fractured quartzite, and schist. The TBM will hole through into the existing 4.88 m (16 ft) dia. horseshoe tunnel where the TBM will be disassembled and removed from the tunnel.

Jan 1, 2001

By D. J. Blickwede

PRESENT knowledge of the effects of time and temperature upon stabilization of the austenite-martensite reaction in steel is fairly complete,1-3 but at the time the work described herein was initiated there was no information about the effects of alloy elements on the phenomenon. However, it has been assumed on theoretical grounds that alloy elements, particularly carbide formers, may have a significant effect on stabilization.' The present work was undertaken to provide information about the effect of two common elements, nickel and molybdenum, on stabilization in hypereutectoid and hypoeutectoid steels. Seven induction-furnace melted, 1.2 pct C steels ' with a variation of nickel from 0 to 6 pct and of molybdenum from 0 to 1.0 pct were used for most of the experiments. Along with these a series of 0.4 pct C steels containing 0 to 6 pct Ni were also studied. The chemical compositions of the steels are listed in Table I. Stabilization in these forged, hot-rolled, annealed, and centerless ground steels was measured by aging brine-quenched specimens (aus-tenite temperature, 1800°F) at 95" and 150°F and then determining the change in specific volume produced by subsequent cooling from room temperature to —320°F.³ In presenting the results the decrease in the change in specific volume, ?V, after various stabilization times is used. This is given by ?V -= ?VO - ?V1 where AVO is the change in specific volume on quenching directly to —320°F and aV, is the change in specific volume on quenching to —320°F after stabilizing for time t. In other words, ?V is a direct measure of the amount of martensite that is lost to the subzero quench as a result of stabilization and hence is greater, the longer the aging time or the higher the aging temperature. The results are shown in Fig. 1. The scatter of the data, which are not shown for clarity and brevity, was sufficient to make the relative location of the curves on the ?V axis inaccurate within ±2x10-5 cc per g. However, some generalities appear which are of interest. Effect of Nickel In the 0.4 pct C steels, up to 3 pct Ni has little, if any, effect on the rate or amount of austenite stabilized at 95°F, Fig. la. Increasing nickel from 3 to 6 pct almost doubles the amount of austenite stabilized in a given time. In the 1.2 pct C steels aged at 95°F, increasing the nickel from 1 to 3 pct appears to decrease the amount of stabilization, and a further increase to 6 pct Ni completely eliminates stabilization as shown in Fig. lb (M, of 6 pct Ni steel was below room temperature). The same behavior was exhibited by these steels stabilized at 1500°F, especially after aging for periods longer than 5 hr, Fig. lc. Thus it appears that up to 1 pct Ni has little effect on stabilization at low or high carbon levels. More than 1 pct Ni increases stabilization at low carbon contents and decreases it at high carbon contents. Ward, Jepson, and Rait5 have found that at inter-

Jan 1, 1954

By Stephen C. Tadolini

The International Ground Control Conference in Mining has always provided an open forum for the publication, presentation, discussion, and often heated debate on roof bolting systems mostly with attention to how, when, and why they work. During the last 24 Conferences at least 170 papers have been presented by International Experts on these ?simple? devices that range in length from 30-inches to 20 ft and from 5/8 to 2 inches in diameter. Roof bolts are primarily mechanically anchored, glued, cemented, or driven. Bolts are placed vertically, angled, or tied together with special fixtures (trusses and slings). They have been termed active, passive, stick-slip, and several other descriptive acronyms or mining slang expressions. This retrospective paper will present the changes in bolt types and usage, point out some of the biggest myths and hail the most significant advances (according to the authors? opinions of course).

Jan 1, 2006

"9.1. IntroductionThe application of the electron microprobe for in-situ analysis of platinum-group minerals (PGM), first reported by Borovskii et at. (1959) and Genkin (1959), has resulted in a large and growing number of analyses of unidentified PGM. Figure 9.1 charts the increase in the number of reported unnamed PGM from 3 in 1959 to a total of 140 by 1979. All these minerals, with the exception of UN1968-5 and UN1976-1, were analyzed with the electron microprobe.There has been no recognised or consistent manner for reporting these unidentified PGM. The term ""unnamed"" has been used for PGM that are considered to be new species without a name as well as for PGM which have not been exhaustively compared to named and unnamed PGM in order to determine whether they are unique. Many of the so-called unnamed PGM are only unnamed because of poor microprobe analyses or because larger than usual elemental substitutions (e.g. Bi for As) made it difficult to calculate the true stoichiometry. Some of these unnamed minerals have been unnecessarily reported with non-stoichiometric formulae, as discussed by Cabri (1980). Better analytical data should reduce the number of such proposals.Another unfortunate practice, possibly used to by-pass the scrutiny of the Commission for New Minerals and Mineral Names, I.M.A., is to report a ""new"" mineral by referring to it by a name made up of its constituent elements. This has been deplored on a number of occasions (cf. discussion in Fleischer et at., 1976, p. 179), but some journals continue to publish such material. The Commission on New Minerals and Mineral Names has not recognised such ""names"" and these PGM are therefore included in this chapter with other unnamed minerals.A further example of inconsistency in reporting unnamed minerals is the report of a specific ideal stoichiometry with no further details (not even an analysis!); sometimes with a note that this will be reported in greater detail in due course. I have also been guilty of similar optimistic statements and, unfortunately, it is not always possible to follow through. Some authors give data on unnamed minerals in such a discrete manner that their reports are sometimes missed in literature searches."

Jan 1, 1979

By Clarence E. Jackson, George G. Luther

The ever increasing array of information concerning the measurement of the effect of the welding process on the properties of a steel is an indication of the tremendous effort that is being expended in this field. The methods that have been considered may be divided into two groups: first, those that measure directly the effect of welding on the ductility of a steel, and, second, those that observe the change in some property, such as the hardness of the heat-affected zone, and assume a direct correlation between this change and the resultant ductility. The nick-bend test is a direct method designed for studying the effect of welding on the ductility of a steel. The test specimen (Fig. I) consists of a bar cut from a plate with a bead weld on the surface. The specimen is prepaxed with a saw-notch placed so as to restrict deformation to the heat-affected zone under the bead weld when tested as a static bend. Failure is caused by rupture of the low-ductility metal in the heat-affected zone. The angle at maximum load is used as an index of the effect of the welding process on the material. In the development of the nick-bend test considerable scatter was noted in some of the results, although the agreement of duplicate specimens welded at the same time and tested consecutively was excellent. Upon further investigation it was found that the change in ductility was dependent upon the interval of time between the welding operation and the testing of the specimen. For the six steels of Fig. 2, the angle at maximum load in lour cases was doubled and in one case was tripled. All steels that have been studied show an improvement in the angle of bend for longer intervals between welding and testing. This same behavior has been found in weldability tests using the Navy T-bend

Jan 1, 1945

By Joseph A. Zupanick

Methane drainage is a mature technology, now commonly practiced in many highly productive underground coal mines throughout the world. Universally, the practice of pre-draining methane will continue to grow as near-surface coal seams become depleted and mining operations are forced to exploit deeper reserves. These deeper coal reserves inherently have higher gas contents. In addition, increases in productivity and extraction rates have caused higher methane liberations per unit of time. As the cost of providing ventilation air increases, the economic justification for implementing a methane drainage program becomes apparent.

Jan 1, 2005

By R. J. Young, S. J. Tennant, A. D. Drummond

"Gibraltar Mines is located on the western slope of Granite Mountain, 230 air miles north of Vancouver, B.C. and 38 miles north of Williams Lake, B.C. There are four mineable zones within the copper-molybdenite deposit: Gibraltar East, Gibraltar West, Pollyanna and Granite Lake. Open-pit reserves are 358 million tons which average 0.37% Cu and 0.016% MoS2 at a 0.25% Cu cut-off. The Granite Mountain pluton is one of the several Jurassic-Cretaceous intrusions which outcrop along the east side of the Fraser River fault system between Williams Lake and Prince George, B.C. The original Granite Mountain quartz diorite has been metamorphosed by a cataclastic deformation which foliated the rock on a regional scale. Attendant to the development of the foliation, the rock was saussuritized such that the present mineralogy is compatible with that of the greenschist facies. The presence of garnet-bearing assemblages is explained by a restricted increase in water pressure. Pre-mineral intrusive phases within the saussuritized quartz diorite are: (1) leucocratic quartz diorite, (2) aplite and (3) quartz-feldspar porphyry. A late chloritized hornblende dacite dyke is post-mineral. Quartz-feldspar porphyry and leucocratic quartz diorite are locally present on the inner sides of the Gibraltar East, Pollyanna and Granite Lake pits. Their presence suggests a core around which occurs an elliptically shaped sulphide-bearing stockwork. The stockwork, which comprises four ages of vein development, is imposed on and partly controlled by the regional foliation of the samssuritized quartz diorite."

Jan 1, 1973

By Adam L. Wesner, A. C. Richardson

DURING World War II the demand for electrode carbon was greater than could be met by the supply of petroleum coke available for this use. It was believed that coke made from an extremely low-ash coal might be a suitable substitute for petroleum coke. Requirements for electrode carbon to be used for the production of aluminum are that the silicon plus iron content shall be not more than 0.14 pct of the coke. However, during the period when petroleum coke was in short supply, it appeared that relaxations of the specifications might be allowed to permit 0.4 pet iron plus silicon in the coke. For this work, the specifications were that the coal should contain less than 1 pet of ash, and the combined iron and silicon content of the coal should not exceed 0.28 pct. Heavy-liquid separations made on a number of coals showed that if certain size fractions of some coals were separated at low specific gravities the resulting float products would meet the required specifications. The objective of this work was to develop a continuous, commercially feasible process for producing low-ash coal. After consideration of various processes, the method chosen was a float-and-sink separation using a solution of calcium chloride as the separating medium. Eagle Seam coal was used for the experiments. The -10 +35 mesh fraction was found to be the most promising feed for producing the low-ash [ ] content coal. A batch of 30 tons of -3/8-in. coal was screened at 10 and 35 mesh; the yield of -10 +35 mesh was 20 pct of the feed. This fraction comprised the feed for the separation tests. In spite of the fact that this portion was screened a second time at 35 mesh, the coal still contained 16 pct that was finer than 35 mesh. Three-fourths of the undersize was in the -35 +48 mesh range. A representative portion of the -10 +35 mesh fraction was subjected to batch float-and-sink separations to determine the best gravity to be used in the continuous tests to obtain a high recovery of low-ash content coal. The heavy liquid used was a mixture of carbon tetrachloride and benzene which assured complete wetting of all of the particles. As usual in batch separations, adequate time was allowed for each separation so that even the near gravity particles had ample time to separate. The separations were made at increments of 0.01 sp gr from 1.25 to 1.28 and also at 1.32 and 1.59. Each specific-gravity increment was assayed for ash content. From these data it was concluded that 1.27 sp gr was best for the continuous separation of the coal. The products from the batch separation were composited into float 1.27 and sink 1.27 sp-gr fractions; these were assayed for ash, iron, and silicon. Table I shows the results of the batch separations. The composite float 1.27 fraction contained 66.04 pct of the total weight, and had an analysis of 0.79 pet ash, 0.073 pct iron, and 0.112 pct silicon, or 0.185 pct iron and silicon combined. These data are indicative of the results possible if a perfect separation is made at 1.27 sp gr under static conditions. Inasmuch as the method under investigation is a dynamic system these results could not be obtained. It remained to be determined, however, just how close to the theoretical results the actual continuous separation would be.

Jan 1, 1952

By H. R. Peiffer

Composite alloys of silver and alumina are shown to resist flow above the melting point of the continuous matrix. The ability to resist flow depends on the fineness of the dispersion and the oxygen content of the silver. It is believed that the oxygen influences very strongly the bond between the molten silver and the finely divided alumina. RECENT needs for materials with high strength and creep resistance at high temperatures initiated mechanical property studies on dispersed phase materials to near the melting point of the continuous matrix material. Results' of these investigations have shown that certain of these materials do have promise for high-temperature applications. Experiments performed on composite materials of silver and alumina by the author have resulted in the discovery of an interesting effect above the melting point of the silver. In these materials the silver was continuous and the alumina very finely divided (Linde B). It was observed that these materials exhibited strength and resistance to flow above the melting point of the silver matrix. The purpose of this paper will be to describe these properties. METHOD OF PREPARATION The materials were prepared by mixing the proper amount of Linde B alumina and high-purity silver oxide. The alumina content was varied from 5 to 20 wt pct alumina in silver in 5 pct steps. The materials were mixed by blending the constituents in an ordinary food blendor using ethyl alcohol as a vehicle. Enough alcohol was added to the powders to form a mixture with the consistency of a thin mud. After blending for about | hr the material was dried and the silver oxide reduced by heating to 450 OC. The material was then pressed at 25 tsi into a -in. billets 3 in. long. EXPERIMENTAL PROCEDURE The specimens were horizontally supported at either end by knife edge supports of cold-rolled steel. This holder was then placed in a "globar" furnace and a chromel-alumel thermocouple placed very close to the specimen recorded its temperature to within 10°C. Each specimen was heated rapidly to 900°C initially. The specimens were held at temperature approximately 30 min and then the temperature was raised 50 deg. The procedure was repeated until deformation was noted. Photographs were made of the specimens at various temperatures and increments of time using a Polaroid Land camera. RESULTS Fig. 1 shows the 5 pct by weight "Linde B" alumina and silver material after reaching 980 °C. Failure occurred after 15 min at this temperature. There were two points of failure and silver collected at them. No additional flow of the molten silver was noted at any other place. Fig. 2 shows a 20 pct by weight "Linde B" alumina in silver specimen. After 30 min at 1400°C, bowing of this material was observed. Other concentrations of alumina were added to

Jan 1, 1961

By Edward N. Trump

Extensive beds of rock salt occur in New York, Michigan, Kansas, and Texas. Wells are drilled through the beds, cased, and equipped with a suspended center tube. By circulating water through such a well, the soluble saline is dissolved and a brine produced. Operation of a well results ordinarily in the formation of an inverted conical cavity in the saline, inasmuch as the dissolving action of the fresh water is more rapid at the top of the bed than at the bottom. Under continued operations, the side wall of the cavity becomes so flat that a blanket of mud is deposited thereon and if the bed is overlain with shale or a soft rock caving follows. Three methods of operating wells have been employed—the "Tully plan," "the Detroit plan," and "the Trump plan." Both the Tully plan and the Detroit plan involve the formation of the aforesaid conical cavity with constant caving of shale above and deposition of mud on the side wall; the Trump plan was developed to avoid both these circumstances and thus materially prolong the life of a well. Details of the three plans follow. The Tully Plan In the Tully plan, the water passes down the annular space between the casing and the center tube, the brine rising in the center tube (Figs. I and 2). An inverted conical cavity is formed, the side wall of which relatively soon becomes so flat that it is blanketed by mud and impurities from the rock salt; this blanket limits dissolving action to the perimeter of the base of the cone, situated at the top of the saline bed. Caving of the overlying strata follows, and the total production of brine from the well is comparatively small. The Detroit Plan In the Detroit plan, the water passes down the center tube, the brine rising in the annular space between the center tube and casing (Figs. I and 2). Initially, this flow forms a pear-shaped cavity in the bottom of the salt bed, but this cavity soon changes in shape to that of an inverted cone, as under the Tully plan, with the attendant disadvantages inherent in that plan. Application of the Detroit plan is limited to salt beds 300 ft. thick as a minimum. This depth of bed is necessary to prevent fresh water of lower specific gravity than the brine from rising in the

Jan 1, 1948

By Walter English

THE four papers making up this symposum have been prepared espe-cially for those who have no knowledge of seismograph prospecting. To many people mathematics is a formidable subject, and many are discouraged from studying seismograph prospecting under the mistaken assumption that the mathematical requirements are severe. In the papers presented here there is not a single mathematical equation. We believe that considerable competence in dealing with some of the most important problems of this work can be attained without any mathe-matical training whatever. At the present time, there is a real need for interpretation of results by persons thoroughly competent to bring geologic experience and imagination to bear on data that are subject to multiple interpretation from a strictly physical viewpoint. Likewise, those charged with the responsibility of planning seismo-graph exploration campaigns would do well to become familiar with as much as possible of the technical aspects of the work. They would then be in better position to judge of its success in individual cases. It has often been said that the seismograph is a new structure-finding tool for the geologists to use. Using a tool and using its product are two different things. One does not use an automatic screw-threading machine when he buys a box of screws at the hardware store. Neither does the geologist

Jan 1, 1939