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By A. M. Gaudin, J. G. Morrow

FLOTATION requires the existence of a definite contact angle. This contact angle, the surface tension of the solution, and adsorption at the solid-fluid interface are quantitatively related. Adsorption of dodecylammonium acetate on hematite was measured for a wide range of concentrations of reagent in solution. Similar measurements for quartz have already been made. Contact angle measurements were then made on polished surfaces of hematite and of quartz immersed in aqueous dodecylammonium acetate solutions, and a functional relationship was sought between adsorption density at the mineral-solution interface and the contact angle. Finally, the surface tension of the aqueous amine acetate solutions was measured. These data were combined to give an evaluation of the work of adhesion for the three-phase system. Specular hematite was crushed and then ground dry in a laboratory porcelain mill, with flint pebbles, to pass a 200-mesh screen. The ground product was sized in a Haultain infrasizer, and one of the granular sizes (cone No. 3) was used in all adsorption tests. A hand magnet was used to remove magnetite and abraded iron. Quartz was removed in a Frantz isodynamic magnetic separator. The purified hematite was leached in aqua regia, washed with distilled water until the washings appeared free of electrolyte by conductance measurement, dried in a low-temperature oven, and stored in a pyrex container. The specific surface of the closely sized hematite was determined by the krypton gas adsorption method.' Three measurements gave an average value of 1350 sq cm per g. Chemical analysis showed Fe -69.37 pct, insol = 0.72 pct. The quartz used in the flotation tests had been prepared by Chang" for an earlier investigation. Demineralized distilled water was used for all test solutions. Dissolved salt content was of the order of 0.03 ppm, expressed in terms of sodium chloride, as estimated from conductance measurements. Dodecylammonium acetate was obtained from Armour & CO. in two forms, the unmarked compound and a preparation marked by carbon 14 in the hydrocarbon chain of the aminium ion. Specific activity of the active salt was 0.134 millicurie per g. The important physico-chemical constants for the primary amine salt have been reviewed by de Bruyn. The calculated effect of hydrolysis of amine salt on pH of aqueous solutions and the effect of pH on the distribution ratio of the alkylammonium ion to free amine are of particular interest. All other chemicals used in this investigation were of analytical reagent grade. A column method' was used for adsorption work. Attainment of equilibrium distribution in the adsorption column depends on the solid-solution contact time, hence upon the volume of solution passed. It was assumed that contact time required for equilibrium would be a maximum for the lowest reagent concentrations. On this premise it was demonstrated experimentally that the passage of 500 ml of solution through the mineral bed was adequate. An aliquot (1 to 5 cc) of the solution to be analyzed was transferred to a small pyrex cup and allowed to evaporate to dryness at room temperature; 4 or 5 mg of unmarked amine acetate were added to the dried sample and the cup and its contents were transferred to the combustion system for analysis. Evaporation at room temperature must be emphasized, as even slightly elevated temperatures result in loss of reagent. A laboratory model G Beckman pH meter equipped with a glass electrode was used to measure pH of amine acetate solutions. The technique of internal gas counting of radioactive carbon dioxide in a Geiger-Muller counter was used. Developed originally by Brown and Miller,- his method was adapted to the analysis of carbon-14 marked flotation reagents by Chang, de Bruyn, and Bloecher. nalytica1 method and procedures have been described in detail by Bloecher.' Contact angles were measured by the captive-bubble technique." The mineral specimens were carefully selected to avoid cracks and inclusions of other minerals. All specimens were mounted in plastic and polished to produce a smooth surface. The final polishing and contact-angle measuring

Jan 1, 1955

ALABAMA Altoona.-Cain, J. America.-Foreman, J. T. Anniston.-Cowie, L. K. Foster, R. N. Ashland.-Sturdevant, J C Bessemer.-Ball, E. M. McKenzie, W. C., Jr Birmingham.-Abbott, C. E. Aldrich, T. H. Aldrich, T. H, Jr. Ashton, J J. Ball, T. L. Blair, C. S. Brown, T S. Bush, M. W.

Jan 1, 1923

By Waldemar Lindgren

The important investigations of Dr. G. F. Becker at Steamboat Springs, Nev., in 1885, aided by the analytical work of W. H. Melville, established the fact that sulphides were being deposited at the surface by hot ascending waters.' Steamboat Springs is situated near the eastern base of the escarpment of the Sierra Nevada, six miles distant from the Comstock lode.

Jan 1, 1906

By H. O. Hofman

PAGE Part I. Decomposition OF Zinc Sulphate by Heating in Air, . 811 I. Introduction............ 811 II. Zinc Sulphate Used,..814 III. Fumes and Pyrometers,........ 816 IV. Heating Zinc Sulphate—Dehydration,...... 817 V. Heating Zine Sulphate—Decomposition...818 (a.) Beginning of Decomposition..818 (b.) Rapidity of Decomposition,..819 (c.) End of Decomposition..823 (d.) Retardations in Heating.-Curve,..825 (e.) Formation of Basic Salts,..826 Part II. Decomposition OF Zinc Sulphate by Heating with Carbon (Reducing Roast), .830 I. Introduction,........... 830 II. Experiments and Results ,.........832 III. Summay,........... 834 Part 111. Formation of Zinc Sulphate by Roasting,... 834 I. Introduction,........... 834 IT. Description of Blende,......... 836 III. Outline of Operations,.........838 IV. Details of Experiments.......... 839 1. Decrepitation,.......... 839 2. IgnitionPoint,....839 3. Sulphatizing-Roast of Joplin Blende..840 4. Sdphatizing-Roast of Warren Blemde ,..843 5. Sulphatizing-Roast with Addition of Pyrite...848 6. Summary of Sulphutizng-Roasts,....... 854 Part IV. Appendix : Formation of Zinc Ferrate...856 Part I. Decomposition of Zinc Sulphate by Heating in Air. I. Introduction. With the exception of lead sulphate. all common metallic

Jan 1, 1905

By S. R. Goodman, Hsun Hu

The rolling texture of an 18-8 stainless steel (Type 304L or 304) has been found to change gradu -allv from the (110)[112] brass type to the (123)[412] copper type as the rolling temperature increases from 200° to 800°C. This texture transition is accompanied by a change in the stacking-fault frequencv or probability, similar to those found pre- In a series of previous publications, it was shown that the rolling texture of high-purity silver changes gradually from the brass type to the copper type with increasing temperature of deformati~n. A similar temperature dependence of rolling texture transition was found in electrolytic copper3—by lowering the temperature of deformation, the normally observed rolling texture of copper changed gradually viously in nonferrous fcc metals—the stacking-fault frequency decreases rapidly with the formation of the copper type texture. These results strongly indicate that the temperature dependence of copper type == brass type texture transition and its correlation with stacking-fault frequency is a general phenomenon in fcc lattices. to the brass type.* In both of these metals, the

Jan 1, 1964

By D. J. Dunn, J. L. Huiatt, T. E. Norman

Corrosion studies in laboratory ball mills and grinding environment simulations produce corrision rates and total metal removal rates much lower than those recorded in operating production ball mills. The corrosion component of ball metal loss in many mills probably represents less than 10% of the total loss, judging from AMAX experience and recent US Bureau of Mines (USBM) tests. Such small absolute losses are consistent with ball metal loss measured in production ball mill marked ball wear tests to determine effects of corrosion and abrasion resisting properties of alloys in operating mills. These indicate that metal hardness and microstructure determine relative metal loss rates of a given situation. The combination of ore characteristics and grinding process dynamics determine metal loss severity. Alloying for corrosion resistance and modification of the milling corrosion environment yield relatively small metal loss reductions. Alloying and heat treatment to produce high hardness and microstructures of high carbon martensite and, for cast irons M7C3 carbides, produces the lowest metal losses in typical wet grinding applications.

Jan 1, 1986

By T. L. Kesler

With only six small spodumene prospect pits, no detailed mapping, and no subsurface information in 1938, the Carolina lithium-pegmatite area now contains four mines among more than 25 properties on which exploratory work has been done. Even the open pit mine of Foote Mineral Co. described herein, from which ten million tons of ore and waste have been removed since 1952, was virgin ground when mapped in 1938-40 1. It has been a privilege to participate in the transition. In 1940, the spodumene pegmatites were known in a 25-mile belt (originally noted for tin prospecting) between Lincolnton, N. C. and Grover at the South Carolina line. Subsequently, Broadhurst 2 reported relatively small bodies northeast of Lincolnton near the Catawba County line. To the south, diamond drilling done in 1953 on the old Ross tin-mine property near Gaffney yielded pegmatite cores containing a few crystals of spodumene. This fact, not previously reported, suggests that some of the pyroxene in the Ross shaft as described by Sloan 3 may be spodumene.

Jan 9, 1961

By Milton Glicken

THE airborne geophysicist is a busy man these days. In his plane he may have the airborne magnetometer, the airborne scintillation counter, and the airborne electromagnetic surveying system. Each of these is an independent tool, but all require additional auxiliary equipment for locating the aircraft in space: recording altimeters and Shoran or aerial cameras. Now there is still another piece of equipment, the airborne magnetic gradiometer, an accessory to the magnetometer. To understand its uses, consider the function of the magnetometer itself. Aside from detecting magnetic ore, the airborne magnetometer finds greatest use in spotting intrusions of igneous material. Where there is enough contrast in magnetic susceptibility of igneous rock and adjacent formations, it outlines the intrusion. Certain minerals also influence the magnetometer directly, but with the exception of magnetite and possibly one or two others, their effect is weak and can be detected only when there is sufficient ore and the magnetometer flight passes very close to it. An igneous intrusion of infinite depth with vertical sides is represented on a magnetometer record by an anomaly, as in Fig. 1. Amplitude of the high depends on susceptibility contrast of the igneous rock. Generally speaking, the edge of the intrusion lies below the point of inflection of the curve, and this point, where the curvature changes from positive to negative on the magnetometer profile, would be near A in Fig. 1, with a counterpart, of course, on the other side. Location of the contact is one of the principal objects of the survey, but finding the precise point is not always easy, as inspection of the curve near A will show. Mineralization is often found at the contact zones, as at B. Magnetic effects, if detected, may be small, as in B', and when superimposed on the anomaly due to the instrusion they are very difficult to discern and analyze. Furthermore, if these small fluctuations are to be perceived by the magnetometer the vertical scale should be large. This increases the slopes of the anomaly and makes detection of small deviations and inflection points even more difficult. The airborne magnetic gradiometer was designed to help overcome these difficulties. What it presents is the first derivative of the magnetometer record with respect to time, that is to say, the slope at any point. Fig. 2 represents an actual magnetometer record (solid line) with the corresponding gradiometer record (dashed line) superimposed. Both records read from right to left. Vertical lines on the original magnetometer record are automatic steps designed to keep the pen from going off scale. The slope of any curve is greatest at the point of inflection or point where the curvature changes sign, and this point is a maximum (or minimum) on the gradi- ometer. The chief advantage of the gradiometer is that maxima or minima are much easier to see and to locate precisely; hence an accurate location for the point of inflection can easily be found. Note that points C and D are more sharply defined than C and D'. Similarly the small fluctuations of the original record, so important to the interpreter, are far more clearly shown at E, F, and G, than on the original record at E', F', and G'. Though not necessarily highs and lows on the gradiometer, they do show up clearly what would take a painstaking analysis to detect on the original magnetometer record. Will the gradiometer have a particular configuration which indicates an orebody? Not necessarily. The total intensity curve, or original magnetometer record, can display an orebody in various ways, depending on dimensions, orientation, latitude, and composition, as well as on direction, flight height, and instrumental sensitivity of the traverse. Where the total intensity can take on so many different shapes the gradiometer must vary too. It is generally recognized that interpretation of total intensity magnetometer records requires an expert analysis; the gradiometer can be of considerable assistance to the expert but it does not replace him. Mechanism of the gradiometer is simple. A Leeds & Northrup recorder in the aircraft records the magnetic gradient simultaneously with the total intensity, which is on another recorder. Fiducial marks are put on both records simultaneously and the speed of the paper through the recorders is kept the same on both. This makes it possible to place one record over the other for direct comparison. In the laboratory the flights are positioned on a map. Maximum and minimum points on the gradiometer, which can then be posted on the map at their proper locations, may be expected to fall along a trend crossing the direction of flight. Trends should indicate the edge of an intrusion, or some other important features, and when superimposed on the total intensity contour map help greatly to locate the points of inflection, or line of zero curvature.

Jan 1, 1956

NEW MEMBERS The following list comprises the names of those persons who became members during the period of May 10, 1918, to June 10, 1918. ABEEL, GEORGE H., JR., Cons. Min. Engr., .4111 Lafayette Ave., St. Louis, Mo. ALLEN, CARL A Metal Min. Engr., U. S. Bureau of Mines, Butte, Mont. BECKER P. FRANK Engr., Lightner Min. Co., 35 Nassau St., New York, N. Y. BOCK, JAMES H., Steam Shovel Foreman, Chino Copper Co., Santa Rita, N. M. CARRON, FRANK X., Civ. and Min. Engr Rock Springs, Wyo. CROWE, THOMAS B., Mill Supt., Portland Mill, Portland Gold Min. Co., Victor, Colo. DOBSON, PERCY GRENSIDE, Min. Engr. and Geol., Crow's Nest Pass Coal Co., Fernie B. C., Canada. ESTABROOK, W. H., Capt., 3d Bat. 20th Engineers, A. E. F., Care postmaster, N.Y. FRASER, 0. B. J., Engr., International Nickel Co. of Canada, Ltd., Port Colborne, Ont., Canada. GARRIDO,. MANUEL F., Min. Engr 109 W. Myrtle St., San Antonio, Tex. GRODSKY, VLADIMIR ALEXANDROVITCH, Cons. Engr., Motor Products Corpn., Detroit, Mich.

Jan 7, 1918

By E. R. Parker, D. L. Martin

During the heat-treatment of silver specimens for tensile tests it was observed that the bars blistered and became brittle when heated in a hydrogen atmosphere. To check this unexpected result, a wide variety of commercial silvers were heated in hydrogen at 850°C. Only a few of the materials developed blisters, the most severe of which is the tube pictured in Fig. I. The microstructure of a cross section of the tube is shown in Fig. 2. The embrit-tlernent is extremely severe at the edge; the blisters result from the severe deformation of the surface material by large under- lying gas pockets. The effects resulting from hydrogen embrittlement of silver have been observed by numerous investigators over a long time l,2,3 although it was only recently that a clear explanation was offered.4 However, the damage resulting from hydrogen embrittlement has not been generally recognized; and it is of advantage to know more about this phe- 1 References are at the end of the paper.

Jan 1, 1943

By D. L. Martin, E. R. Parker

During the heat-treatment of silver specimens for tensile tests it was observed that the bars blistered and became brittle when heated in a hydrogen atmosphere. To check this unexpected result, a wide variety of commercial silvers were heated in hydrogen at 850°C. Only a few of the materials developed blisters, the most severe of which is the tube pictured in Fig. I. The microstructure of a cross section of the tube is shown in Fig. 2. The embrit-tlernent is extremely severe at the edge; the blisters result from the severe deformation of the surface material by large under- lying gas pockets. The effects resulting from hydrogen embrittlement of silver have been observed by numerous investigators over a long time l,2,3 although it was only recently that a clear explanation was offered.4 However, the damage resulting from hydrogen embrittlement has not been generally recognized; and it is of advantage to know more about this phe- 1 References are at the end of the paper.

Jan 1, 1943

By H. T. Bowman

For more than 80 years the Bessemer process has depended upon the ability, skill, and judgment of the blower, although as early as the I860's it was recognized that the process would benefit by some type of instrumental contro1.l IIowever, instruments with sufficient recording speeds did not exist, so the end-point determination was always dependent upon the blower's eye. This placed an obstacle in the way of precise experimental work, because of the absence of the necessary records and reference points as reported by Work.2 The use of the photocell provided the instantaneous record of the blow that made this experimental work possible and provided more scientific control for the process as discussed by Graham,3 A brief description of the progress of the blow will illustrate the recording function of the instrument. The silicon in the iron is being oxidized during the first minutes of the blow, as pointed out by Henning4 in a table showing the order of metalloid elimination. The product of this oxidation is a solid that remains in the converter, so there is virtually no flame during this part of the blow. This low flame luminosity is illustrated by the flame recording shown in Fig. I, where the silicon blow is plainly marked. The dull flame of the silicon blow gradually gives way to the brilliant carbon flame as the increasing quantities of carbon monoxide formed inside the converter burn to dioxide upon contact with the atmosphere above the vessel. When the carbon reaches some low value under 0.20 per cent, there is insufficient menoxide formed to maintain the dioxide flame, so its intensity drops. Throughout the flame drop carbon continues to burn, until at some value around 0.05 per cent an arrest occurs in the recorded drop. This point has been designated as the end point. The period of time from this end point until the vessel is turned upon its side and blowing has stopped has been called the afterblow. This afterblow is used as a measure of the degree of metal oxidation, and uniformity demands that it be controlled within narrow limits. Iron and blowing conditions are likely to change several times during a turn, necessitating corresponding changes in end-point control. It is the purpose of this paper to discuss these changes, the factors that make them necessary, and their bearing upon the quality of steel. Carbon-FeO Relationship In the Bessemer process oxidation relationships are precise. Fig. 2 shows a graph of the carbon-FeO relationship. The familiar "bomb-test" method, described by Mccutcheon and Rautio,5 was used for obtaining these and all other dissolved FeO values herein reported, all tests being taken from the converter before deoxidation unless otherwise noted. All tests of 0.10 per. cent carbon and above were obtained from metal blown for duplexing. McGinley and Woodworth6 reported iron oxide values for blown metal, but their tests were obtained by a . different method than were those

Jan 1, 1942

By H. T. Bowman

For more than 80 years the Bessemer process has depended upon the ability, skill, and judgment of the blower, although as early as the I860's it was recognized that the process would benefit by some type of instrumental contro1.l IIowever, instruments with sufficient recording speeds did not exist, so the end-point determination was always dependent upon the blower's eye. This placed an obstacle in the way of precise experimental work, because of the absence of the necessary records and reference points as reported by Work.2 The use of the photocell provided the instantaneous record of the blow that made this experimental work possible and provided more scientific control for the process as discussed by Graham,3 A brief description of the progress of the blow will illustrate the recording function of the instrument. The silicon in the iron is being oxidized during the first minutes of the blow, as pointed out by Henning4 in a table showing the order of metalloid elimination. The product of this oxidation is a solid that remains in the converter, so there is virtually no flame during this part of the blow. This low flame luminosity is illustrated by the flame recording shown in Fig. I, where the silicon blow is plainly marked. The dull flame of the silicon blow gradually gives way to the brilliant carbon flame as the increasing quantities of carbon monoxide formed inside the converter burn to dioxide upon contact with the atmosphere above the vessel. When the carbon reaches some low value under 0.20 per cent, there is insufficient menoxide formed to maintain the dioxide flame, so its intensity drops. Throughout the flame drop carbon continues to burn, until at some value around 0.05 per cent an arrest occurs in the recorded drop. This point has been designated as the end point. The period of time from this end point until the vessel is turned upon its side and blowing has stopped has been called the afterblow. This afterblow is used as a measure of the degree of metal oxidation, and uniformity demands that it be controlled within narrow limits. Iron and blowing conditions are likely to change several times during a turn, necessitating corresponding changes in end-point control. It is the purpose of this paper to discuss these changes, the factors that make them necessary, and their bearing upon the quality of steel. Carbon-FeO Relationship In the Bessemer process oxidation relationships are precise. Fig. 2 shows a graph of the carbon-FeO relationship. The familiar "bomb-test" method, described by Mccutcheon and Rautio,5 was used for obtaining these and all other dissolved FeO values herein reported, all tests being taken from the converter before deoxidation unless otherwise noted. All tests of 0.10 per. cent carbon and above were obtained from metal blown for duplexing. McGinley and Woodworth6 reported iron oxide values for blown metal, but their tests were obtained by a . different method than were those

Jan 1, 1942

Coal Division Industrial Minerals Division Minerals Beneficiation Division Mining, Geology and Geophysics Division Elmer A Jones, President President-elect Will Mitchell, Jr, Past President J B Morrow, Eastern Regional Vice-President G Donald Emigh, Central Regional Vice-President J D Forrester, Western Regional Vice-President R B Ladoo, Treasurer John Cameron Fox, Secretary AIME 29 West 39 St, New York 18, N Y

Jan 1, 1957

By Claude P. Heiner, Carl S. Westerberg

OBSERVATION of the clinkering action of coal from the Castle Gate D seam in underfeed stokers over a period of years has given rise to the present investigation of the effect of bony coal on clinkering. Some very costly examples of slagging clinkers in particular cases have been of especial interest to the authors. In such cases coal analyses and ash-softening and fluid temperatures have been found of little value. In general, it was noted that slagging was accompanied by a somewhat higher ash content of the stoker slack, and the suspicion naturally arose that foreign matter was the troublemaker. One would naturally suspect bony coal and rock impurities because of their occurrence and prevalence within the seam and the relative absence of sulphur or other impurities in the coal mined. The test results given herein indicate that the concentration of the bony coal and rock impurities in the coal determines the clinkering tendencies of the ash during combustion. CASTLE GATE D SEAM Extending from the Utah-Colorado line near Grand Junction, Colo., westward to Greenriver, Utah and thence in semi-circular form north and westward to Castle Gate, and from there southward to Mt. Hilgard in central Utah, is a line of nearly perpendicular cliffs, composed of interbedded massive sandstone and shales, making up the coal-bearing horizon of the Mesaverde formation of Upper Cretaceous age. The cliffs face roughly concentrically toward the south and southeast and the strata, with conformably enclosed coal beds, gently dip away from the face of the cliffs and at right angles to their front line. Back of these cliffs the mountain masses rise to an altitude of from 8000 to 10,000 ft. above sea level. Stretching away from their foot is a great shale plain, on which the towns are situated and over which the railroad lines and highways run. The Castle Gate mines enter the coal beds at their outcrop; the workings extending within a particular coal bed away from the outcrop and under the mountain mass back from the cliff line (Fig. 1). Throughout the Mesaverde formation in the Castle Gate general area, there are from two to five workable coal beds. Usually not all of these are coincidentally of workable size and merchantable quality throughout any given large tract. In the Castle Gate mine area, the base of the Mesaverde horizon and coal measures is marked by a massive, cliffmaking, gray sandstone bed 6o to 8o ft. thick. Locally this is referred to as the "Castle Gate sandstone floor." Frank R. Clark, in U. S. Geol. Survey Bull. 793, designates it as the "Aberdeen sandstone." At Castle Gate the various coal beds are designated by the letters A, B, C, etc., commencing with the lowest bed. Fig. 2 is a graphic generalized vertical section, compiled from physical exposures

Jan 1, 1941

By O. W. Ellis

The writer has dealt with the effect of various methods of melting copper upon the gas content of the metal.' The copper referred to in his earlier paper was melted in the foundry both in the oil furnace and the electric furnace. As the metal did not measure up to conductivity standard, the term "casting copper" was applied to the material in the title of the paper. It was thought that some information in regard to the gases in a sample of overpoled copper might also be of interest, and through the courtesy of C. R. Stevens, superintendent of the copper mill of the West-inghouse Elec. & Mfg. Co., such a sample was obtained. The metal was chill-cast in the form of an ingot about 7 in. long, 2 1/2 in. deep (from the base to the raised surface of the ingot) and from 1 3/8 to 1 7/8 in. wide. A photograph of part of the ingot is shown in Fig. 1. The effect of over-poling on the surface of the metal is here quite clearly shown.

Jan 1, 1929

By O. W. Ellis

The writer has dealt with the effect of various methods of melting copper upon the gas content of the metal.' The copper referred to in his earlier paper was melted in the foundry both in the oil furnace and the electric furnace. As the metal did not measure up to conductivity standard, the term "casting copper" was applied to the material in the title of the paper. It was thought that some information in regard to the gases in a sample of overpoled copper might also be of interest, and through the courtesy of C. R. Stevens, superintendent of the copper mill of the West-inghouse Elec. & Mfg. Co., such a sample was obtained. The metal was chill-cast in the form of an ingot about 7 in. long, 2 1/2 in. deep (from the base to the raised surface of the ingot) and from 1 3/8 to 1 7/8 in. wide. A photograph of part of the ingot is shown in Fig. 1. The effect of over-poling on the surface of the metal is here quite clearly shown.

Jan 1, 1929

Minnesota School of Mines Experiment Station, University of Minnesota, Minneapolis, Minn For copies of Bulletins or a list of publications, address The Director Bulletins available are Bulletin 1, Iron mining in Minnesota, by C. E Van Barneveld (1912), $1, 2, Concentration tests on Mesabi ores, by W R Appleby and E Newton (1913), 3, Preliminary concentration tests on Cuyuna ores, by W. R Appleby and E Newton (1915), 4, Bibliography of Minnesota mining and geology, by W. Gregory (1915); 5, Manganiferous iron ores of the Cuyuna district, by E Newton (1918), 7, The future of the Lake Superior district as iron-ore producer, by E W. Davis (1920), 9, Magnetic concentra¬tion of iron ore, by E. W Davis (1921); 10, Ball mill crushing iii closed circuit with screens, by E W Davis (1925); 12, Minnesota manganiferous iron ore in relation to the iron and steel industry, by T L Joseph and S P Kinney (1927). A mining directory of Minnesota, by J J Craig, is published annually.

Jan 1, 1933

1. Healthy and active Local Section organizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stim¬ulated by appropriation of funds from the Institute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings .held and the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local. Section should submit: (a) a report showing in reasonable detail its income, and expenditures for the preceding calendar year; (b) a statement of the number of. members to whom announcements of each meeting had .been mailed; (c) a record of meetings held, the character of the program, and _ attendance of members at each; and (d) any further facts having a bear¬ing on its financial requirements for the coming year.

Jan 1, 1937

By W. J. Reagan

All of the material described in the following paper is within the following specifications: carbon, 0.50 to 0.85 per cent; phosphorus and sulfur, 0.04 per cent max.; manganese, 0.60 to 0.85 per cent; silicon, 0.20 to 0.30 per cent. Steels with much lower carbon contents can be handled in exactly the same manner. One of the first things necessary to basic open-hearth slag control is uniformity of charge, particularly as to the silicon content and the percentage of lime charged. Our past work has shown that the silicon content of the charge is more important than the carbon content in determining the carbon at which a heat will melt. We have found that by keeping the silicon content of the charge about 0.60 to 0.65 per cent, and with a lime charge of about 7 per cent (limestone equivalent), our heats melt sufficiently high in carbon to allow a moderate feed of ore and the slag will be of low iron oxide content. In making a heat of 0.75 carbon steel we endeavor to have the heat melt at about 1.20 per cent carbon. The iron oxide content of the finishing slag depends upon the final phosphorus desired; for a given ratio of lime-silica in the slag, the lower the phosphorus desired in the final steel, the higher the iron oxide content of the finishing slag must be. By reducing the lime charge to a minimum, the heats melt faster, and by keeping the silicon content at the desired figure the heats melt with a high SiO2 slag, which has been shown in previous work to give a low iron oxide slag. In most of our work, using a 180,000-lb. charge and with basic pig containing about 1.20 per cent silicon, we use a lime charge of 8500 lb. of limestone and 2000 lb. of burnt lime. The pig charge is about 48 per cent of cold pig, and the charge contains a large percentage of works scrap. This causes a heat to melt with about 1.20 to 1.30 per cent carbon, for a heat that will finish about 0.75 per cent carbon. This gives a heat that will need a feed of about 2000 lb. of ore, and also a slag with an FeO content of about 4 to 5 per cent at melting. The additional FeO obtained from the ore addition will bring the FeO in the slag at tapping to about 6 to 7 per cent. It is necessary to carry quite a fluid slag to prevent pickup of FeO, as a too heavy slag causes FeO to build up in it, giving a finishing slag with a greater FeO than is desired. By adjusting the lime charge of a basic open-hearth heat, a very sensitive adjustment of the slag may be obtained. The figures in Table 1

Jan 1, 1935