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By AIME AIME

THANKS to the excellent preliminary work of: the Division officers and the local committee the fall meeting of the Coal Division at Bluefields was a brilliant success. West Virginia was at its best with its beautiful mountains, good roads and foliage, just beginning to turn to autumn colors. The meeting began on time and was kept on time throughout. The papers were-well prepared and, being on subjects of live interest, provoked 'lively discussion. One factor in bringing this about was that they were not too numerous and that with one exception copies had been submitted in advance a sufficient time to permit of them having been studied. The Friday morning session was presided over by John .J. Lincoln of the Crozier Coal and Coke Co. and president of the Pocahontas Coal Operators Association. After brief announcements by Thomas H. Clagett, chairman of the local committee, regarding plans for the two day's involved, and by Howard N. Eavenson, chairman of the Division, the reading of papers was taken up.

Jan 1, 1931

By Claus Guenter Goetzeil

(New York Meeting, February, 1937) The object of this investigation was to determine whether silver alloys could be used instead of the currently employed insert of high-expansion Average Coefficient per Deg. C. over Range 20° to 200° C. Pure aluminum..................................... 24.6 X 10-6 Cast low-expansion Si-Cu-Ni-A1 piston alloy............ 20.0 X 10-6 High-expansion austenitic Cu-Ni cast iron.............. 19.3 X 10-6 Cast steel (0.25-0.35 C, 0.40-1.0 Mn).................. 12.6 X 10-6 Cast iron (3.15 total C, 2.16 Si)....................... 12.8 X 10-6 Pure silver.......................................... 18.9 X 10-6 austenitic ferronickel alloy, to reduce the wear of ring grooves in light metal pistons. A typical example of a piston containing a ferronickel insert is shown in Fig. 1. The high coefficient of expansion of silver made it worthy of consideration, while the small size of the insert would render its use feasible in Germany as an emergency measure. The coefficients of linear expansion of several metals and ailoys are as shown in the table above. Obviously the melting point of the insert must be high enough to prevent it from melting when the light alloy is cast around it. This imposes a lower limit of about 850" C. for the solidus of the silver alloy. Pure silver melts at about 961" C., so that the tolerable depression in the solidus is rather small. To avoid deformation of the insert during use a Brinell hardness number of at least 60 appears necessary.

Jan 1, 1937

By M. J. Ginsberg, N. A. Gokcen

THE preliminary study of electrochemical desul-furization performed by Ohtani and Gokcen1 left a number of points concerning the process to be investigated. Two of these were i) the determination of the effect of greater current and voltage on the desulfurizing Flower of acid slags (% CaO/% SiO2- 1) and ii) the possibility of the loss of silica in slag by the reactions 2C (in metal) + SiO2 (slag) = Si (in metal) + 2CO(g) and C + SiO2 (in slag) = SiO(g) + cO(g) proceeding to a point at which the composition of the slag was sufficiently altered toward the basic side so a1.s to noticeably affect the rate of de-sulfurization. The apparatus and the procedure used in the present investigation were the same as those used by Ohtani and Gokcen, except the control circuit was connected to 120 v dc instead of 24 v dc and thereby allowed greater freedom in choosing the values of both current and voltage. The graphite crucible containing the melt and serving as the cathode was 3-in. high, and was of 1 1/2-in. ID with a graphite bar of 3/8-in. diam and 8-in. length threaded into the bottom for electrical connection. This was placed into a magnesja outer crucible with a hole in the bottom and alumina insulation was packed between the two crucibles. A charge consisting of 180 g of

Jan 1, 1962

By F. M. Lewis, J. E. Goodman

A larger, slow-speed, under-loaded ball mill and hydraulic classifier have almost doubled grinding efficiency at the lsabella mill. TENNESSEE Copper Co. operates two ore con-A centrators, the London and Isabella mills near Copperhill, Tenn. In 1948 and 1949 the small ball mills and rake classifiers in the London concentrator were replaced by one large ball mill and one hydraulic classifier. This new ball mill was designed oversize so that it could be operated at slower than normal speed. The proper operating conditions were established and the results published.' Later it was found that this mill operated more efficiently with a small ball charge." While this London grinding practice was being developed, the Isabella grinding circuit was not changed in any way. It remained a conventional two-stage rod mill—ball mill combination, the rod mill in open circuit and the ball mill in closed circuit with a rake classifier. Study of the data indicated that grinding cost could be lowered by converting to the London practice, but not enough would have been saved to warrant the expense of converting. No plan for improving this grinding operation could be developed. In 1953 this study was reopened when plans were made to increase the Isabella mill output from 1150 to 1500 tpd. At this time the grinding circuit consisted of a 6x12 rod mill followed by a 6x12 ball mill in closed circuit with a 6-ft rake classifier. Another 6x12 ball mill and 6-ft rake classifier would have been sufficient equipment and would have been the simplest and cheapest installation. However, this would have offered no improvement in grinding efficiency or operating cost. If, on the other hand, the grinding operation could be converted to the London practice, by installation of one large 101/2x9x9 tricone mill and a 10-ft hydroscillator,2 lower operating costs would justify the additional investment. Economics: Table I presents estimates for the two schemes for enlarging the Isabella mill. In the first scheme, column 1, one 6x12 ball mill and one 6-ft rake classifier were to be added. In the second scheme, column 2, the existing small ball mill and rake classifier were to be retired and one large mill and hydroscillator were to be installed. Estimated savings from the difference in operating costs made an attractive return on the additional investment for the large mill and hydroscillator. Actual costs of carrying out this plan are tabulated in column 3b. It will be seen that these costs follow the estimates in column 3a very Closely. The return on the additional investment is calculated from the difference in the operating cost in column 1 and the actual operating cost in column 3b. This too come very close to the estimate. Power and Steel: Power requirements and steel consumption for the rod mills and ball mills, both actual and estimated, are presented in Table 11.

Jan 1, 1958

By W. F., Dietrich

THIS paper deals with the- methods of mining the high-grade clays of California. Although the majority of the clay pits in the state are operated on a scale that is small by comparison with most metal mines, this very fact results in a diversity of methods and gives rise to problems of selection of the method best suited to given conditions. Two or three operators in California produce approximately 500 tons per day of a single kind of clay from a single pit. About five varieties of clay are mined on a scale of 200 to 400 tons per day; not over fifteen varieties are mined on a? scale of 50 to 200 tons per day; and more than 50 varieties are mined at a rate of less than 50 tons per day. It is the aim of this paper to delimit, insofar as the data at hand permit, the conditions and scale of operations that favor the selection of each dominant method of mining that is actually being applied at California properties. Details of the occurrence and utilization of the clays of California have been given in a recent bulletin and are not considered here.

Sep 1, 1928

By W. E. STOKES

SOME extension of flying service to the mining industry occurred in 1938, particularly in Canada, where freighting activity radiated from Edmonton into the new northern mining districts. Again the airplane demonstrated its usefulness in getting new equipment rapidly into the field and in decreasing shutdown time while waiting for repairs. An 18-ton Caterpillar tractor with shovel attachment was disassembled, brought in by plane, and placed in operation at Berens River, Ont., within seven days after its de- livery at Winnipeg. At Central Patricia a mill breakdown required the replacement of a full mill head and trunnion with ball bearings, weighing 2700 lb. The Canadian Airways Junkers, termed the "flying boxcar," was called in from Yellowknife, 1300 mi. away, and the new installation was completed three days later.

Jan 1, 1939

By L. P. Teas

Although 1930 has been a year of stagnation, proration and curtailment, the Gulf Coast has measured up to its tradition in the matter of interesting and significant discoveries. Only 2 domes and 7 new structural areas were brought into the producing column in 1930, whereas, in 1929, 13 domes and one structure were added to this list, yet a total of 14 new producing horizons were proved on various domes and structures. On 5 domes new flanks were successfully tested for commercial production. The year 1930 has shown at Barber's Hill that oil in commercial quantities may exist below salt or cap. Numerous wells have been drilled through cap, or even salt itself, into good producing sands. The past year has been particularly notable in the interest and in the number of deep holes drilled. Two wells have gone below 8000 ft. in each of the states of Texas and Louisiana, and in the two states together 14 wells have gone below 7000 ft At the beginning of the year only one well was producing below 6000 ft. in coastal Texas, while at its end, 19 wells were producing or had produced. Geophysical discoveries and activity on the Coast have waned and this type of work has moved further inland. The peaks of production at Pettus, Barber's Hill, Raccoon Bend, Refugio, Orchard and at Humble, in Texas; and at Lake Barre, Port Barre, Black Bayou, White Castle and Vinton in Louisiana, were seen this year. These were new peaks for Humble and Vinton, of course, these fields having previously gone through periods of peak flank production. In Table 1 the completions listed are for the entire month of December in both years. It is remarkable that in 1930, a year of overproduction and proration, there were actually more wildcat operations at its end than at the end of 1929; but it is gratifying that the operations in the proven fields were exactly one-half what they had been at the end of 1929. The price of A grade coastal crude, or oil below 25" Bé., has been cut from $1.30 at the beginning of the year to $1.00 at its close; and B grade, or oil above 25o Bé., has been reduced from a price range of $1.15 to $1.63 down to a range of from $0.75 to $1.22. In spite of these reductions there has been no proration program on the Coast. Systematic

Jan 1, 1931

By David W. Brunton

(San Francisco Meeting, October, 1911.) MINE-DRAINAGE and the ever-increasing demand for water on the plains have within the past few years necessitated the driving of a great number of adits and tunnels, including many of considerable size and great length. In most instances, ex isting conditions have called for extreme rapidity of execution; and this necessity, coupled with the high altitudes at which most of the work has been carried on, excessive freight-rates, and difficulty -of access, has involved many complex and interesting problems. One of the most rapidly executed undertakings of this class is the Laramie tunnel, recently completed for the Laramie-Poudre Reservoirs & Irrigation Co. This tunnel is driven through Green ridge, a spur of the Continental Divide, which separates the Laramie river from the Cache-la-Poudre in Laramie county, Colo. Green ridge is extremely persistent, and further northward in Wyoming is known as Sherman hill, the highest point on the Union Pacific railway. At the point where the tunnel is driven, two opposing bends bring these streams within 2.5 miles of each other, with a difference in elevation of 500 ft. The rock exposed on the banks of the two rivers does not differ materially in hardness; and, without a geological study of the conditions involved, it would appear that the difference in the depth of erosion of the two streams is due principally to the greater volume of water at this point in the Cache-la-Poudre, which has a drainage-area above the tunnel-portal of 110 sq. miles, as against 30 sq. miles of natural drainage for the Laramie. To increase the water-supply at the tunnel, however, this latter amount has been augmented by two side collection-canals, which bring the available drainage-area up to 84 square miles. The nearest railroad shipping-point to the eastern portal is

Apr 1, 1912

By Robert K. Waits

The resistivity, temperature coefficient of resistance, stability at 200°C, and structure of annealed Si-Cr films have been studied as a function of film cowposition. Colorimetric analyses of the films indicated 20 to 60 wt pct Cr over the resistivity range of 1 to 10-4 ohm-cm. Resistors were delinealed by photolithographic etching, contacted with aluminum, and mounted in TO-5 packages. The average temperature coefjicient of resistance, a, between 50" and 150°C is related empirically to the film resistivity, p, by a (ppm per °C) = -2900 - 1140 log p (ohm-cm). Near a resistivity of 3.5 x 10-3 ohm-ctn (30 at. pct Cr) , the temperature coefficient changes from positive to negative. The temperature at which the resistance maximum occurs increases with decreasing resistivity. The conduction mechanism between —196" and +360 C appears to have two components—an activated conduction dominating a1 lord chromium content and higher temperatures and a linearly temperature-dependent conduction dominating at high chromium content and low temperatures. Electron diffraction patterns showed the films to consist of Cr3Si and amorphous silicon. Resistors thicker than 150A typically drifted less than 0.6 pct after 5000 hr stor-age at 200°C. Resistors as thin as approxinzately 80°A that had a silicon overlayer showed similar stability. Such films had sheet resistivities of 10 kilohm per square and temperature coefficients near —600 ppm per "c. THIN-FILM resistors having sheet resistivities greater than 1 kilohm per square are required in many integrated circuit applications. A process for producing such resistors should be compatible with present circuit fabrication and packaging, including exposure to maximum temperatures of 300° to 570°C during contact alloying, die-attach, and ceramic package sealing. In addition, the resistors should have a low temperature coefficient of resistance and change less than 1 pct during storage at temperatures up to 200°C for 1000 hr or longer. Reports of work beginning in 1949 at Battelle Memorial Institute indicated that, among other materials, the silicides of chromium, Cr-Co, molybdenum, tantalum, and tungsten were worthy of further study as high-stability resistive films. Later work on Si-Cr films vacuum-deposited by flash evaporation from a tungsten boat1 led to the conclusion that Si-Cr had "excellent properties for development into high- stability ... resistive elements". More recently, Si-Cr films have been vacuum-deposited from a tantalum boat,2 from a BeO-coated tantalum boat,3 by flash evaporation from an electron-beam-heated tungsten Source,4 and by triode sputtering.5 This paper describes a study of Si-Cr films vacuum-deposited by electron-beam heating of Si-Cr alloys. Resistivity, temperature coefficient of resistance, stability at 200°C, and structure were studied as a function of film composition. EXPERIMENTAL PROCEDURE Film Deposition. Si-Cr sources were prepared by vacuum-melting pressed pellets of mixtures of powdered chromium (99.9 pct, -100 mesh, Lunex Co., Pleasant Valley, Iowa) and silicon (99.99 pct, -325 mesh, United Mineral and Chemical Co., New York). A permanent-magnet focused electron-beam gun having a water-cooled copper crucible was used to heat the pellet until complete melting occurred. The mixture was then kept molten for an additional 5 min. The alloy thus formed was used as the source material for Si-Cr film depositions using the same electron-beam gun. Pieces of semiconductor-grade silicon ingots were used as sources for silicon depositions. The films were deposited within a standard vacuum evaporator having an 18-in.-diam Pyrex bell jar, a liquid-nitrogen-cooled trap, and a Consolidated Vacuum Corp. 6-in. diffusion pump containing Dow Corning DC-705 pump fluid. The substrates were thermally oxidized* silicon wafers 2 to 2.5 cm in diam. The

Jan 1, 1969

By Wm. A. Haven

As soon as the likelihood of American participation in the war was established, and in spite of the fact that we can produce almost as much as all other countries combined, the demand for prompt deliveries of iron and steel products from American factories began to exceed their utmost capacity, and, after fifteen months of practically full operation, has continued to do so. Therefore, it would seem worth while to review some of the aspects of the supply and demand for steel as well as the efforts that are being made to bring them into balance. It is still being debated as to whether the situation should be defined as a real shortage that will persist through the emergency period or as a temporary one than can be relieved by less drastic measures than a Government-sponsored program of expanding existing plants and building new ones.

Jan 1, 1942

By Bernt Ellingsaeter, Terkel Rosenqvist

IN the silicothermic reduction of magnesia, burned dolomite is treated with high grade ferrosilicon in an evacuated steel retort at temperatures between 1150° and 1200°C. The following reaction is assumed to occur MgO + CaO + 1/2 Si (Fe) - Mg(g) +- & Ca,SiO, + Fe with the equilibrium constant on the basis of thermodynamic data for the substances involved and assuming unit activity for all solid constituents, Kubaschewski and Evans' calculated the magnesium pressure as a function of temperature logp,, (mmHg) = 15.06-1.61 T- log T- 13,16O/T. Pidgeon and King," who measured the magnesium pressure by means of a flow method, found values about three times the calculated ones. This may be caused by uncertainties in the thermodynamic data, but may also be caused by the formation of other reaction products, such as Ca,SiO,, which is known to be the stable silicate in equilibrium with lime. Whatever the exact reaction may be, it is evident that as long as all other factors are maintained constant the magnesium pressure will vary with the silicon activity, viz: p,, = &,. (p,,) ", where (p,,)" is the magnesium pressure by the reduction with silicon of unit activity. In the present investigation, p,,, was therefore measured for various grades of ferrosilicon and their silicon activities were calculated. The experimental method was similar to that used by Pidgeon and King. Briquettes of burned dolomite and Fe-Si alloys were placed in a 1 in. heat resistant steel tube and were heated to 1200°C. By means of a flow of purified hydrogen, the magnesium vapor was swept into a condenser filled with steel wool. From the amounts of hydrogen used and magnesium condensed the magnesium partial pressure was calculated. First a tube of 28 pct Cr steel, and later a tube of Kanthal D (a ferrous alloy with 22.6 pct Cr, 2 pct Co, and 4.5 pct Al), was used as a heat resistant tube. The latter tube showed the best heat resistance. The dolomite used had the following composition: 43.6 pct MgO, 55.5 pct CaO, 0.2 pct K,O + NalO, 0.2 pct Fe,O,, and 0.3 pct insoluble. The ferrosilicons were prepared from 98 pct Si of technical grade (0.7 pct Al, 0.3 pct Ca, and 1 pct Fe) by melting with various amounts of electrolytic iron of high purity. The alloys thus obtained were analyzed on their iron and silicon contents, which added up to between 99 and 100 pct. The amounts of reactants were chosen so that there would always be an excess of the oxides, and the average decrease in silicon content during the experiments would be about 1 pct. Most of the reaction occurred in the part of the reaction mixture facing the gas flow. The change in the silicon concentration in the part facing the condenser was, therefore, negligible. To facilitate the reaction, about 1 pct fluorspar was added to the briquette mixture. Fluorspar does not enter the reaction, but is known to act as a

Jan 1, 1957

The General Electric Co., in cooperation with the Montana School of Mines and under a research grant from the Anaconda Co., is presently experimenting on a new non-explosive method of breaking rock with radio-frequency electrical power. The method is known as electrothermal forcing. It must be understood that present equipment has not been designed to perform primary blasting functions. Its conceived use will be restricted to small pieces of rock too large to pass through a chute or grizzly. However, even this use is still far in the future. Experiments to date have been limited mostly to rock smaller than 18 in.

Jan 11, 1961

Discussion of the paper of JOEL H. WATKINS, presented at the New Fork meeting, February, 1915, and printed in Bulletin No. 98, February, 1915, pp. 391 to 411. H. Rims, Ithaca, N. Y.-It is interesting to contemplate to what extent the American pottery industry would be affected in case the English supply of china clay were shut off for a considerable period of time. The English deposits are very large, and are worked on a most extensive scale. They are more easily and probably more cheaply worked than our American deposits, which are of vein-like nature. The American producer of washed clay is not always as careful as the foreign miner and washer of this material, although he has improved in recent years. Our American washing plants are, furthermore, not as economical of material as it seems to me they might be, for the reason that more or less of the finest clay is often allowed to overflow, due to insufficient settling tank capacity. This fact is often shown by the milky character, of the streams into which the waste water is discharged.

Jan 5, 1915

By C. H. Keplinger

WARTIME factors have strengthened the production engineering consciousness of the petroleum industry. The basic principles of sound oil-production technology have been accepted as the standard by the industry and the governmental co-ordinating agencies. Every effort is being made to furnish larger quantities of petroleum with a minimum expenditure of materials and under strict conservation practices. The sphere of influence of production engineering extends from fundamental reservoir control of withdrawal rates and reservoir pressures to bolstering production from stripper wells. Serious transportation difficulties in moving oil to the East Coast have stimulated secondary recovery operations in the Appalachian and East Central oil-producing states. Diminishing discovery of new oil reserves by exploration activities increases the importance of promoting efficient oil-producing methods and practices throughout all productive areas in the United Nations.

Jan 1, 1943

By AIME AIME

THE Coal Division holds its fall meeting in the Pocahontas coal field, at the West Virginian Hotel, Bluefield, W. Va., Oct. 9 and 10. The first day will be a busy one-two sessions for the presentation of papers and a dinner in the evening. Hon. E. Fudge, Assistant Undersecretary, Mines Department, and R. V. Wheeler, head of the Mines Research Board of Great Britain, will be the guests of the Division. Mr. Wheeler will discuss the British Mining Act as relates to the coal industry. George S. Rice, Chief Mining Engineer, U. S. Bureau of Mines, will present an account of the recent meeting at Buxton in England, of representatives of England, Germany, France, Belgium and the United States to formulate a plan and to correlate research work now in progress in the various countries. The second day the members will be the guests of the operators on a trip through the Pocahontas field. The work of preparation for the meeting is being actively pushed by committees headed by T. H. Clagett, R. M. Lambie and H. D. Smith, and a good attendance, both local and from the general membership of the Division, is anticipated. Because many will make the trip by car the principal automobile as well as rail-road connections to Bluefield are given here. The program for Friday, Oct. 9, follows:

Jan 1, 1931

NEW MEMBERS The following list comprises the names of those persons who became members during the period Feb. 10 to Mar. 10, 1915: Members BANKS, HAROLD PURDY, Min. Engr 61 Broadway, New York, N. Y. BARAGWANATH, JOHN G., Min. Engr., Morococha Mining Co.; Morococha, Peru. BEESON, JOSEPH JOSIAH, Min. Geol Stanford University, Cal. CALLOWAY, ALFRED W Pres., Davis Coal & Coke Co., Cumberland, Md. DEETRICK, JAMES W., Mgr., Republic Iron & Steel Co., 826 Pennsylvania Ave., Youngstown Ohio.

Jan 4, 1915

By H. A. Doerner

PROPOSALS to use hydrocarbon or natural gases for the reduction of zinc from oxide materials may be traced back through Patent Office files to the early years of the present century. Natural gas at rates cheap enough to compete with solid fuels has been available at or near one major zinc district for more than a decade. That the seemingly meritorious and economically interesting applications of these proposals have not devel-oped into workable processes for direct production of zinc by natural gas cannot be completely ascribed to the proverbial conservatism of the zinc industry. It is possible to produce spelter commercially in normal times from zinc oxide and carbonaceous reducing agents without having a very precise understanding of the chemistry of the process. The reduc-tion by hydrocarbons is not, however, in this class, and the technical complexity of this reduction metallurgy and chemistry prohibits solution of the inherent difficulties by the "hit and miss" methods that are some-times thought to be practical. In a thermodynamic study of the chemistry of zinc smelting, Maier1 made a preliminary study of the chemistry of the use of methane for reducing zinc oxide by thermodynamic means, pointing out that the following reactions, the limits of which could be theoretically predicted, were important: ZnO + CH4 = Zn(gas) + CO + 2H2 [1] CH4 = C -I- 2H2 [2] ZnO + CO = Zn(gas) + CO2 [3] ZnO + H2 = Zn(gas) + H2O [4] Other possible reactions, not discussed in the reference quoted, are: CO2 + CH4 = 2CO + 2H2 [5] H2O + CH4 = CO + 3H2 [6]

Jan 1, 1933

By John H. Hollomon

A REVIEW of the steps which have been made to increase knowledge in the field of ferrous physical metallurgy during the closing period of World War II brings both pleasure and disappointment. Contributions of great value have been made, to be sure. However, due partly to the stress of the times, researchers in this field have been in the main directing their attention toward the short-range problems involved in the development and production of materiel for war. Furthermore, publication of the results of a great number of studies has had to be delayed. Much of the German work may, indeed, be lost entirely, owing to the efficiency of our bombers, which managed to account for most of the famous Kaiser Wilhelm Institut of Dusseldorf, not to mention the other large laboratories and manufacturing plants throughout that country. It would seem safe to assume, however, that fundamental research in Germany had been forced to give way to the shallow, but more pressing, engineering problems of a country trying to avoid defeat. In Russia the picture has been clouded by the limitations imposed upon comunication; but this much does seem clear: Russia alone among the great nations of the world has maintained her long-range view and has continued to foster research of the most fundamental type. English workers; on the other hand, appear to have been able only to meet the demands of the pressing problems of war, and their studies have been of the short-range variety. That metallurgical research of any sort should have continued in France during this chaotic period in her history would seem impossible, but, amazingly, a small handful of scientists did manage to carry on their work, and it is to be hoped that more will be heard from them in the future.

Jan 1, 1946

By F. R. Brotzen, D. L. Davidson

ALTHOUGH much effort has been devoted to the problem, the nature of plastic flow in bcc metals is still not fully understood. Some of the difficulties encountered stem from the scarcity of information on orientation effects and the uncertainty as to the glide system in these metals. In an attempt to provide some of this information, the present investigation was carried out, using zone-refined molybdenum single crystals deformed in tension and in direct shear. Considerable evidence exists to indicate that the primary slip system for molybdenum is (110) <111>.1,2 Figs. 1 and 2 indicate that this is, indeed, the case for direct shear at room temperature (see Ref. 3 for a description of the shear-testing equipment and procedure). Moreover, from Fig. 2, the shear stress on the (123) is lower than that on the (112). This would be the case if, as has been suggested,4,5 slip on these two planes is in reality com-

Jan 1, 1965

By J. Chipman, N. J. Grant, R. Rocca

Desulphurization of liquid iron by reducing slags of the electric-furnace type was studied from 65 heats. Variations were made in basicity over a wide range and in FeO up to about 5 pct for their effects on desulphurization. The role of FeO in desulphurization from the blast furnace, to the electric furnace, to the oxidizing conditions of the open hearth is shown to fit a relatively simple pattern of behavior. THE mechanism which controls the desulphurization of molten iron by basic slags has been the object of several investigations. In particular, equilibrium determinations have been made both in the field of basic open-hearth slags, which have a high iron-oxide concentration, and in the field of blast-furnace slags which have a very low iron-oxide concentration. In both cases the desulphurization ratio has been found to increase with increasing basicity of the slags; however, the mechanism of desulphurization differs in the two cases. In basic open-hearth slags desulphurization occurs mainly as a partition of iron sulphide:&apos; FeS * (FeS) and the desulphurization ratio is approximately independent of iron-oxide concentration in the slag. In blast-furnace slags the concentration of iron oxide is very low as a result of the highly reducing conditions in which they are formed. The controlling reaction for desulphurization is then:2,3 FeS + (CaO) <=* (CaS) + (FeO) The slags of the reducing stage in the electric furnace have an iron-oxide concentration which is intermediate between blast-furnace and open-hearth slags. The study of the mechanism of desulphurization for these slags has been the object of this investigation. The importance of low (FeO) in the slag for desulphurization was first verified by Bardenheuer and Geller,& who found that high desulphurization ratios were obtained in highly reduced slags. It was recognized" hat iron oxide in the slag becomes a controlling factor in desulphurization only at FeO concentrations approximately under 5 pct. A recent investigation conducted by Buehl,7 upon the suggestion of one of the authors, confirmed this opinion from the results obtained from a heat conducted in a small arc furnace. In the present investigation, slags of very high basicity, such as often are encountered in the basic electric furnace, could not be studied, but equilibrium data have been obtained for slags in a wide basicity range. The iron-oxide concentration in these slags ranged from 0.08 to 15 pct and was controlled by the addition of silicon to the metal. Other constituents of the slags were mainly CaO, MgO, SiO2, A120,, and CaF,. The experimental technique was essentially the same as that of previous investigations.1 8-lo In an open magnesia-lined induction furnace, 65 lb of Armco ingot iron was melted. An atmosphere of hydrogen was maintained over the melt for 1 hr to bring the carbon content down to approximately 0.010 pct maximum. The bath then was exposed to air for 25 min to remove hydrogen. The electrodes were put in place, and the furnace was operated from this point on in an atmosphere of nitrogen. A synthetic slag was added to which additions of silicon and iron sulphide were made. A rate study conducted at the beginning of this investigation had

Jan 1, 1952