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By J. A. Norden

MUCH has been written concerning the hoisting equipment of various mines -throughout the country, but most of the literature on the subject, if not all, describes equipment of extraordinary capacity and the small and medium-sized outfits have been neglected. The hoisting equipment here described is capable 'of handling about 1200 tons per day. It has not been worked, to capacity, but 600 to 700 tons, together with men and materials, have been handled in two shifts without any great effort. Only one shaft extends from the surface to the lowest levels of the mine; see Fig. 1. It is composed of three compartments, two of which are used for hoisting and the third for water, air, and electrical lines, and for sinking purposes. In 1909, this shaft was raised from the 1000-ft. (304-m.) level to the 700-ft. There a station was cut and an air hoist installed. At this time all mining operations were confined to the upper levels of the mine; that is; above the 700-ft. The. ore was-dropped to this level through chutes from the 300-, 400-, 500-, and 600-ft. levels and then lowered in cars on cages to the 1000-ft., which is the main haulage adit, the mill and railroad bins being about 3000 ft. from the shaft. Orebodies were, in due time, developed on the 1000-ft. level and below. Therefore, in 1913, the shaft was sunk to the 1150-ft. level and thereafter sinking was continued at regular intervals until the 1500-ft. level was reached. But, hoisting from the 1300-ft. level was a difficult, and slow process with the antiquated air hoist, so, in 1916, it was derided to raise the shaft to the surface and install a modern, electrically operated hoist. This was completed early in 1917 and the hoist was in operation in March of that year.

Jan 8, 1920

By H. K. Shearer

Drilling for oil and gas in Arkansas in 1934 showed more activity than in any year since 1929; with a total of 96 completions, including 36 oil wells, 1 gas well and 59 dry holes. Of the producers, the lone gas well and 35 oil wells were in old fields, and one wildcat producer opened a new pool. Of the dry holes, 16 were in or near fields and 43 were wildcats. The total reported initial daily production of the oil wells was 9013 bbl., averaging 252 bbl. per well. Active drilling operations numbered 65 at the close of the year, compared with 26 at the beginning.

Jan 1, 1935

By S. S. Hsieh, J. R. Lehr

Bench scale beneficiation studies were made on Idaho dolomitic phosphate rock using the TVA carbonate flotation process. The process used diphosphonic acid as a phosphate mineral depressant and fatty acid as a carbonate mineral collector. Silica was subsequently rejected as float using an amine collector, with phosphate product recovered as the sink fraction. Two samples of prepared flotation feed from commercial operation were used. One contained 21% P205 and 3.2% MgO. The other contained 26% P205 and 1.8% MgO. The results indicate that concentrates containing 31% to 33% P205 and 1% or less MgO can be obtained, with about 80% P205 recovery.

Jan 1, 1986

By Linn Bradley

Introduction MARKED differences of opinion have been expressed by engineers interested in cleaning iron blast-furnace gases for use in hot-blast stoves and under boilers, in reference to the advantages of a hot-dry method over a cold-wet method. One point at issue involves the sensible heat energy in the moisture contained in the gas. Some advocates of the cold-wet methods claim that the condensation and resultant removal of the greater portion of this contained moisture by wet scrubbing, spraying or similar methods, results in a saving of some of this sensible heat energy, by reason of the fact that water vapor has a high capacity for sensible heat energy and may carry from the exit of a hot-blast stove, for example, more heat units than are sacrificed or lost when the gas is cleaned by this cold-wet method. Other advantages claimed for the latter method are: That gas burns more readily when it is free from moisture in any form; that because gas is made denser by cooling and removing the moisture it has a higher calorific value than hot gas carrying moisture; and that higher flame temperatures are obtained when the gas is cleaned by the cold-wet method. A search through the available literature fails to disclose any extensive calculations or records of conditions obtained in practice, bearing upon these phases of gas cleaning. This paper deals with these problems from the standpoint of the economy of using a gas of higher flame temperatures, of improved stove design, and of economy in the gas-cleaning department. Calculations have been made which show that by cleaning the gases by a cold-wet method the sensible heat energy of the blast-furnace gases is greatly reduced; and, in general, this loss of heat energy is far greater than that lost from the stoves or boilers due to the sensible heat capacity of the water vapor if carried away by the exit gases. By making use of the

Jan 2, 1917

By D. R. Parrish, V. J. Berry

Reverse combustion is one thermal method of recovering hydrocarbons from porous undergrortnd formations containing oil or tar. In applying this method, air is introduced via an injection well and the mixture of air and hydrocarbons is ignited in the production well. A combustion zone then recedes toward the injection well, counter-current to the air flow. If the combustion-zorie temperature is sufficiently high, the oil or tar irz place is distilled arid cracked. The hydrocnrhon flows as a vapor to the production well and subsequently is condensed at the surface. Maximum temperature and velocity of morcment arc the two dependent variubles defining the progress of the combustion zone. A theoretical analysis has been made of heat flow in the reverse-comhustion process as.srtrning linear flow in a homogeneous system. The differentirll equatious, which include the oxygen-hydrocar-hon rctrction rate, have been solved numerically. Rescllts indicate that the maximum temperature reached and he cornbustion-zone relocity both increase with an incrense in air-injection rote. Heat loss to surroundings has little effect on the maximum comhustion-zone ten?perature achieved, but it is reflected in a reduced com-bustion-zorzc, velocity. It is also predicted that an increase in the oxygen-hydrocarbon reaction rate results in a reduction in the maximum temperature reached. The calculated results are in agreement with results from reverse-combustion experinments using samples of a tar sand. INTRODUCTION Reverse combustion is one thermal method of recovering hydrocarbons from porous underground forma-tions containing oil or tar.' In applying this method, air is introduced into the underground formation via an in-jection well. In one or more adjacent production wells, the mixture of air and hydrocarbons is ignited at the sand face. The combustion zone thus formed recedes toward the injection well, counter-current to the air flow (Fig. 1). Under certain conditions, the rate of recession of the combustion zone is sufficiently rapid that only a small fraction of the hydrocarbon at any point in the formation is consumed by combustion. If the combustion-zone temperature is sufficiently high, the uncon-sumed oil or tar in place may be partially distilled or cracked. This material then can flow as a vapor with the gaseous combustion products to the production well and subsequently be condensed at the surface. Under other conditions, the combustion-zone temperature may be so low that little, if any, of the hydrocarbon is vaporized. Nevertheless, the viscosity of the hydrocarbon may be reduced enough so that other recovery methods subsequently can be applied to produce oil at attractive rates. The maximum temperature achieved in the combustion zone and the velocity of movement are the two dependent variables defining the progress of the combustion zone. Presumably. knowledge of these factors will permit estimates to be made of oil recovery efficiency, oil and gas producticn rates and average amount of injection air required per barrel of oil recovered. The maximum temperature and combustion-zone vclocity are, in turn, expected to be dependent upon air flow rate, heat losses to surrounding formations, physical properties of the rock and the hydrocarbon. the extent to which the porous formation is saturated with the hydrocarbon, the rate of oxidation of the hydrocarbon and the amount of heat released. It is desirable that the relative importance of each of these factors be understood so that the results of laboratory tests of oil recovery by reverse combustion can be properly interpreted in terms of expected field performance. It is particularly desirable to assess the importance of heat lcsses because these are difficult to control or eliminate

Albin. B . R Billings. Mont . '28 Amnter . Nathan L 26 Broad St.. New York . N . Y . '28 Bache . Jules S 42 Broadway. New York. N . Y . '28 Borrett . C . P . 5338 Harper Ave .. Chicago. I11 '28 Baum . Frank G. . Cons . Hydro-Electric Engr Camel'. Shasta Co. . Cal. '23 Baylean, William S Russ Bldg .. San Francisco. Cal . '28 Bean, Louis H .. V.P.. Dwight P . Robinson & Co.. lnc 126 E . 46th St New York. N . Y . '28 Beatty . Roes J . 1106 First National Bank' Bldg .. Chicago . Ill . '28 Benwell . Oswald F . 110 Gilpin St .. Denver. 1310 . '28 Beymer. Albert 9.. V.P .. Keystone. National Bank Pittsburgh. Pa . '28

Jan 1, 1929

By B. M. Burchfiel

CALIFORNIA possesses such an abundance of ceramic materials other than clays, that she is quite independent of other states and foreign countries so far as these materials are concerned. Certain users import some feldspar, silica, and allied minerals, but they do so from choice and not necessity. Production is largely for home consumption, so the total volume of ceramic materials produced is comparatively small. Many small deposits of the materials here under discussion are worked by individuals, and their output sold to individual grinding companies or users. The data given here shall be confined to the larger deposits and developments because they give a truer picture of typical deposits, operations, and materials.

Jan 1, 1936

By Arthur F. Taggart

TO all Mineral Dressers, but particularly to those in the Coal and Industrial Minerals Divisions: Ted Counselman, retiring after two years at the helm of the Milling Committee, pointed with pride to the continued growth of that committee, and sang the swan song "Why ain't we a Division of Mineral Dressing?" Our genial Secretary pointed out, handily, that, you see, the way the Institute is divided there are several blocks running across this way here, and one running all the way down here, and another running part way down here, and they all cut across each other like this, and anyway the miners want to be a Division now, so why not you Mineral Dressers be good and not upset the big Institute organizational chart? And anyway again, Divisions have vested interests, and a Division of Mineral Dressing would take something away from Coal and something from Industrial Minerals, and any good institutional man can see that a Division would never give anything up. It was all quite confusing, and apparently not too convincing, because then the Milling Committee went ahead and voted unanimously it is a good idea, let's see what the other fellows think about it as well.

Jan 1, 1944

New York State Museum, Albany, N. Y. D H. Newland, State Geologist. A complete list of publications or the latest lists of available publications will be sent upon application. A series of Bulletins on The Mining and Quarry Industry of New York are available as follows: Bulletin 51 (1910), 15 cents; 161 (1911), 20 cents; 166 (1912), 20 cents, 174 (1913), 20 cents; 190 (1915), 15 cents; 277 (1925-26), 50 cents; 295 (1927-1929), 40 cents. Another series discusses the Geology of the State by Quad¬rangles, available as follows: Bulletin 153, Broadalbin Quad (1911), 25 cents; 154, Sche¬nectady Quad. (1911), 20 cents, 170, North Creek Quad . (1914)

Jan 1, 1933

By B. J. Guarnera

There have been major changes in the makeup and nature of the uranium exploration industry in recent years. Significant price increases precipitated an increase in exploration activity-according to the Department of Energy, exploratory drilling in 1977, by 140 companies, was almost 8 million m (26 million ft). This represents a 37% increase over the prior year's drilling. Projections for 1978 indicate at least 9 million m (30 million ft) of exploratory holes will be drilled in the US. Exploration expenditures in 1979, including land acquisition, drilling, and other costs, were estimated by DOE at over $236 million. Domestic expenditures for 1978 are estimated at over $250 million.

Jan 10, 1978

By Guy W. Crane

The geology of the Tintie mining district, fully treated, would occupy an elaborate monograph. This less comprehensive paper is devoted primarily to the occurrence and origin of the orebodies of the district, while space is given to those phases of the general geology only which seem necessary to a proper setting of such a discussion. The first geological report on the Tintic district to be issued was that by Tower and Smith, published in 1899, in the form of a paper in Part III of the Nineteenth Annual Report of the U. S. Geological Survey, and also as Folio No. 65, Geologic Atlas of the United States. About four years ago a second investigation was begun by Waldemar Lindgren and G. F. Loughlin, of the U. S. Geological Survey. With the exception of a paper on the oxidized zinc ores of the Tintic district by Mr. Loughlin, the results of their work are still unpublished. The writer's acquaintance with the district began in the fall of 1913, and has extended over a period of about two years. 1. Location The Tintic district lies about 65 miles due south of Salt Lake City, and on the west central slope of the Tintic Mountains, a short range, which forms the connecting link between the Oquirrh Mountains on the north and the Canyon Range on the south—the group constituting the first of the Basin ranges to the west of the Wasatch Mountains. The productive portion of the district embraces an area about 6 miles long and 2 miles wide, which is divided between Juab and Utah Counties. Within this area are the towns of Eureka, Mammoth, Robinson, Silver City, and Knightsville. All these points are tapped by the Denver & Rio Grande and S. P., L. A. & S. L. Railways. 2. Topography As in most of the Basin ranges, topographic relief is strong, dropping rapidly from peaks of 8,100 ft. above sea level to elevations of 5,600 ft. in Tintic Valley on the west and 4,500 ft. in Goshen Valley on the east.

Jan 1, 1916

By William R. Webster

This is a subject which our Institute has made peculiarly its own. In the first volume of its Transactions the analysis of steel received attention, and every subsequent volume has borne witness to the acuteness and industry of our members in the investigation of this subject. The keynote mas struck, in this as in so many other lines of progress, by A. L. Holley, in his paper on " Tests of Steel," read at the Easton meeting of October, 1873 (Trans., ii., 116)—an essay which may rank as a classic by reason of .its elegant form, logical force, and clear prevision of all the bearings of its theme, Taken together with the brief report of the discussion which followed it (in which Dr. Drown emphasized the effects of heat-treatment and mechanical handling, and Dr. Sterry Hunt the importance of minute variations in chemical composition, and of possible isomeric and allotropic conditions), it constitutes, after the lapse of twenty-five years, an admirable and adequate introduction to the long list of technical papers which have succeeded it. Three years later came the epoch-making papers of Dr. C. B. Dudley on the relation between the chemical composition and physical properties of steel rails, which, with the voluminous discussion they evoked, constitute a special volume, published by the Institute, and full of useful suggestions. If Dr. Dudley could be induced to resume this investigation, he would doubtless be able to solve many points still uncertain or disputed. But I cannot undertake to review the history of this subject, as represented in our Transactions—still less to restate all the contributions to it which have been made in books or in papers before other technical societies, since the initiative was taken by the Institute. My more modest purpose is to indi-

Jan 1, 1899

By RUSSELL C. FLEMING

GILSONITE is a brilliant black, tarry-like bitumen, classed technically with glance pitch and graharnite as an asphaltite. As found it is brittle, breaking much like ice, and has a conchoidal fracture. Purest forms are used in the manufacture of paints, varnishes, electrical irisulatiorl, and inks for rotogravure; molded articles such as switch handles, telephone mouthpieces, and but- tons are made from the intermediate grades, and the poorer grades are used for the saturation of felt. According to the U. S. Bureau of Mines figures, production grew from about 4000 tons mined in 1904 to 55,000 tons in 1929. This asphaltic substance is found only in the Uintah basin in northeastern Utah, in veins over a wide area. Veins in the vicinity of Fort nuchesne were first discovered about 18G2, on what was then the Uintah Indian reservation, and the vein matter was originally called Uintaite because of that fact, In the early days, S. H. Gilson. of Salt Lake City, was so persistent and zealous in his efforts to develop the deposits and find a market that the name gilsonite was given to the material. Later, the wider and more renowned wins near Wayson and Dragon, in extreme eastern Utah, became the main supply.

Jan 1, 1932

The Pueblo Viejo Mine, a 7, 250 mtpd (8,000 stpd) gold-silver cyanidation plant built by Rosario Dominicana S. A., was described in Volume I of this monograph. At the time of writing that volume, Pueblo Viejo had not yet gone on-stream and operating data or costs could not be presented. Since that time this information has been obtained and several interesting modifications and an expansion have been made to the plant. Because Pueblo Viejo is the largest open-pit gold mine in the world and one of the world's leading gold-silver operations with production of approximately 31 kg (1,000 oz) gold and 125 to 155 kg (4,000 to 5, 000 oz) silver per day, the authors have updated the previous data and flow sheet. The Dominican Government, which held a 4670 interest in Rosario Dominicana S. A., completed purchase of the mine to gain full control in 1979. Rosario Resources will continue to manage the mine, at least until the end of 1980. Gold was produced at Pueblo Viejo almost 500 years ago with initial production in the year 1505. Rosario Resources became interested in the property in 1969 and found surface oxidation had rendered the upper portion of the ore body amenable to direct cyanide treatment. The treatment of the underlying gold-bearing sulfide zone is still undergoing metallurgical studies. The ore is considered to be a laterite; and because there appeared to be few boulders in the ore zone, only a 400 m (16 in. ) square grizzly was initially installed ahead of the mills when the plant went on-stream in late 1974 at a design capacity of 7,250 mtpd (8,000 stpd). Operation also proved the ore to be harder than was originally anticipated. During 1967 a 1. 25 m by 1. 5 m (48 in. by 60 in. ) jaw crusher was installed to -feed the 1, 000 mt (1, 100 st) mill bin. Minus 200 mm (8 in.) crushed ore is fed directly to two 5.5 m by 1. 8 m (18 ft by 6 ft) semi-autogenous mills re-powered with 750 km (1,000 hp) motors and 50 mm (2 in.) grates. Each mill product is screened at 13 mm (1 /2 in.) by a vibrating screen. Screen oversize from each mill is combined on a single return belt equipped with a magnetic head pulley for grinding ball removal. The non-magnetic oversize is then split into two fractions for return to the primary mills. Originally, a minus 6 mm (1/4 in ) product was made on each screen and fed to a 300 kw (400 hp) 2.6 m by 3. 7 m (8-1/2 ft by 12 ft) regrind mill. During a plant expansion in 1978, an intermediate mill of 746 kw (1,000 hp) was installed to operate in open circuit on the combined primary mill

Jan 1, 1981

By F. C. Canney

Geochemical prospecting seeks hidden mineral deposits by sampling for variations in the chemical composition of naturally occurring materials. Usually the samples are of soils and other products of weathering and erosion—surface materials extremely susceptible to contamination by human activities. Except when a survey is conducted well away from populated areas, contamination is an ever-present hazard. The program's success is particularly endangered when the contaminants are the elements sought; if these occur erratically throughout an area, spurious anomalies completely unrelated to mineralized areas can be formed. Evenly distributed contamination can be dangerous too, if it raises the background to such a level that true anomalies can no longer be easily detected. Suppose, for example, that in an area where the lead background is 20 parts per million the soil over a lead vein contains 1000 ppm of lead. Here the contrast would be 50 to 1, which is very satisfactory for geochemical surveying. Now if 1000 ppm of lead from some source were added evenly to the soil in this area, the contrast would be reduced to about 2 to 1, and the anomaly would no longer be readily detectable because a threshold of significance twice the value of the background is the minimum generally used for interpreting geochemical data. Of the many possible sources of contamination, probably most important are smelter fumes, which may distribute large quantities of metal contaminants over many square miles of ground. For several reasons, the investigation reported here was begun in the Coeur d'Alene district in northern Idaho: 1) a lead smelter has been operated in this district since 1917 and an electrolytic zinc plant since 1928, and presumably the contamination patterns are strongly developed; 2) to evaluate the usefulness of certain geochemical techniques, V. C. Kennedy and S. W. Hobbs of the USGS had already studied the distribution of copper, lead, and zinc in the soils (both in background areas and other veins) and in the water and plants, providing a criterion for measuring the magnitude and effect of soil contamination; 3) one of the economically important parts of the district lies south of the South Fork of Coeur d'Alene River and within a radius of five miles of the reduction plants near Smelterville (Fig. 1). In this area, and in the entire district, conventional methods of prospecting are hindered by heavy vegetation and thick soil cover, and the possibility of contamination by smelter fumes has discouraged geochemical prospecting. Should data reveal that geochemical prospecting could be done successfully in such an area, a particularly useful tool would be available to mining companies and prospectors searching for concealed orebodies in this economically important part of the district. The field work on which this report is based was done from July 28 to 31, 1955. It should be emphasized that this was reconnaissance study only, and therefore far from exhaustive. Previous Investigations in U. S. : The first geochemical survey known to have been affected by contamination was conducted in 1940—a geobotan-ical reconnaissance made in the Michigan copper district by a private company. Geologists found striking variations in the copper content of oak and maple leaves, but unfortunately the high copper isograds of the study seemed to be related more to the Calumet and Hecla copper smelter fall-out than to mineralized ground.' The leaves of one oak tree near the smelter contained 0.4 pct Cu. Similar contamination was reported by Clarke (Ref. 2, p. 41), who conducted experimental geochemical soil and botanical surveys at Ray, Ariz. He found that the leaves of oak trees growing in unmineralized ground near Superior, Ariz., contained more copper than the leaves of oak trees growing on the capping of the Ray orebody and attributed this fact to contamination from the fumes of the Magma smelter at Superior. According to H. E. Hawkes,3 soils and stream sediments in the Superior area are also severely contaminated. Hawkes' work there has shown a copper content averaging 0.5 pct in the surface horizons of soils within one mile of the smelter stack. Samples taken only a few inches below the anomalous surface samples showed only background copper values. In 1950 L. C. Huff' of the USGS made a geochemical survey in an area near Jerome, Ariz., and found considerable zinc and copper in the soils over unmineralized basalt close to Clarkedale, Ariz., and over limestone close to Jerome. As the amounts were notably greater than could reasonably be expected to be derived from the underlying rocks, Huff suspected airborne contamination from the smelter at Clarkedale. Description of Area: The area sampled in detail (Fig. 1) for the study presented here is one of strong relief. The dominant watercourse is the westward-flowing South Fork of the Coeur d'Alene River. East of Kellogg the South Fork flows in a rather narrow canyon, but its valley floor widens considerably to the west where much of the flood plain is covered by an extensive veneer of mining, milling, and smelting debris. South of the South Fork and between Big Creek and Pine Creek is a mountainous area where

Jan 1, 1960

By E. M. Murphy

(Presented by invitation at a meeting of the Spokane Local Section of the Institute, Feb. 17, 1912.) EIGHT years ago the Hecla mine, a lead-silver producer, situated at Burke, Idaho, was producing ore from but two levels, the 300- and the 600-ft. All hoisting was done with a 12- by 16-in. slide-valve, double-reel, hoist. The hoist was being worked to its capacity and was unsuitable for hoisting from greater depths. As the work of opening a new level was about to be started, it became necessary to remodel the then-existing equipment or install a new hoist. The recent advent of electricity from Spokane had made available a cheaper power than steam. By a series of tests conducted throughout the Coeur d'Alène district, it was found that it cost $109 per year to generate a horse-power with steam. Electric power was to be had for $50 a horse-power per year. It was decided to substitute for the engines a motor-drive, of sufficient capacity to operate from the 900-ft. level, and ultimately install an entirely new hoist. After disconnecting the engines, installing a new shaft, and making a few minor changes, a 300-h-p., 2,300-volt, 514-rev. per min., variable-speed motor of the induction type was geared to the reel-shaft. The reels were supplied with 3/8 by 4-in. flat rope, and the duty of the hoist was about as follows: Cage, 1,700; ore, 2,600; car, 1,400; rope, 2,250; total, 7,950 pounds. The Bristol ammeter chart, Fig. 1, shows the combined current-consumption of the hoist- and mine-motors. The large intermittent load is clearly shown ; this produced harmful fluctuations in the voltage of the long, lightly-loaded, 60,000-volt transmission-line from Spokane to the Coeur d'Alènes. The power company received no compensation for the increased cost of producing power for this intermittent or fluctuating load. In order to protect its system from similar excessive

Sep 1, 1912

By J. G. Thompson

PROJECT 8411 of the U. S. Bureau of Standards, sponsored by the Iron and Steel Division of the A.I.M.E., is an attempt to define more concisely than has been possible heretofore the accuracy and the Limits ' of usefulness of the ' various methods now in use for the determination of oxygen as it exists in ferrous materials. It originated in correspondence between John Johnston and other metallurgists, and was brought to the attention of the Iron and Steel Division of the Institute at the Annual Meeting in February, 1933. As reported in MINING AND MET,ALLURGY, Vol. 14, page 152, March, 1933, "Dr. Johnston introduced, and those present adopted, a resolution that the Iron and Steel Division of the A.I.M.E., believing that a careful comparison of the several methods now in use for the analysis of steel for nonmetallic elements such as oxygen is highly desirable, heartily endorses the proposal that the U. S. Bureau of Standards act as a clearing house " in this matter, undertaking the final preparation and allocation of identical samples to those laboratories willing to collaborate in this important question, and collate the results re- ported back to the Bureau.'"

Jan 1, 1934

By Albert E. Wiggin, Frederick Laist

Early ill 1914 it was decided to test, on a fairly large scale, the treatment by flotation of Anaconda slime and mill tailing. For this purpose a standard-type Minerals Separation machine was installed at the Washoe Reduction Works during May and June, 1914. This was followed by the installation of a full-size Callow pneumatic machine plant. Experiments were also made, on a smaller scale, with the Froment, the Towne, the Fields, and the Anaconda flotation machines. The last-named machine was developed at this plant. In addition to the tests made in the standard-type Minerals Separation machine some tests were made using a Minerals Separation machine of the sub-aeration type. During the series of experiments a large variety of oils was tested. Experiments were also conducted using both round-table feed and tailing to determine whether it would be better to displace the round tables by flotation for the treatment of the slime, or to supplement the round tables by flotation of the round-table tailing. A series of tests was also made on the treatment of the mill tailing by grinding followed by flotation to determine the relative merits of flotation and leaching for the treatment of this product. In addition, flotation tests were made on mixtures of mill tailing and slime. The round-table feed referred to above is the total slime from the mill. It contains about 35 per cent. colloidal solids and approximately 90 to 95 per cent. of the total solids will pass through 200 mesh (0.067 mm.). It assays from 2.3 to 2.6 per cent. Cu. The mill tailing referred to above is the total discard from the mill, exclusive of the slime. It is all finer than 2 mm. and about 90 to 95 per cent. will remain on 0.25 mm. It assays about 0.60 per cent. Cu. A brief summary of the experimental flotation results follows:

Jan 1, 1917

By Northcutt Ely

International developments affecting foreign in- vestments in 1960-61 were many, varying from region to region and differing with respect to various categories of investments. Total value of U.S. private investment abroad in 1960 was approximately $32.7 billion, an increase of $2.9 billion over 1959. Production and distribution of mineral resources was, by a sizeable margin, the most important function of American capital working in foreign countries in 1960. Investment in mining or petroleum interests totaled approximately $14 billion, or 42% of all direct foreign investment. In- vestments by industry for 1960 were as follows: Petroleum-10.9 billions, Mining-3.0 billions, Manufacturing-11.2 billions, Utilities-2.5 billions, other-5.1 billions. American investors found Canada and Latin America to be most desirable in 1960 with the greatest percentage of American capital in all areas centered in the petroleum and mining industries. The areal breakdown of total American investments is as follows: Canada-$11.2 billions, Latin America-$8.4 billions, Western Europe-$6.6 billions, Middle East-$1.2 billions, Far East-$1.2 billions, Africa-$.9 billions, other areas-$3.2 billions.

Jan 3, 1962

By Howard N. Eavenson

TWO months ago, just after the coal code hearing in Washington, one of our leading liberal weeklies printed a study of the coal industry made by an economist in the Administration, and on the outside cover bad it featured as "Coal-A Dying Industry." There are, of course, different opinions as to the accuracy of this characterization and I want to present some of the facts about the outlook for the bituminous industry for a short time ahead. In view of what has happened in the industry within the recent past it would be futile to attempt to make any prophecy about what is likely to occur in the future. We all know that a prophet is not without honor save in his own country, but it is likely that anyone undertaking this role about this industry would soon find himself in no man's land. One can, with some slight degree of safety perhaps, outline present conditions and tendencies and draw some inferences as to what the future may hold.

Jan 1, 1933