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By K. E. Beu

IN the measurement of retained austenite concentrations in steels using the integrated intensity method,1 Averbach has pointed out" that the absorption factor A(0) for a flat sample making a glancing angle 4 with the incident X-ray beam can be combined with his constant factor R to obtain our constant factor" G provided that "1—There is no preferred orientation in the sample, and 2—The geometric requirements [for the sample, film, and X-ray beam] have been met precisely."' If A(0) can be combined with R to give G according to the equation G = R . A(0) [14] then the possibility for making non-compensating errors in the austenite determination has been eliminated. This has been described previously in a technical note." Because of the brevity of the previous note,3 it was impossible to emphasize the fact that the two conditions on preferred orientation and geometry can be easily met experimentally, contrary to Aver-bach's statement that: ". . . the necessary conditions must be tested experimentally for each determination, and this is done most easily by observing whether the apparent absorption has the form of Eq. 2 [the theoretical equation for A(0)]."" he way in which these two conditions can be met experimentally will be discussed briefly to help clear up this point. In addition to these two conditions, other factors such as sample shape, homogeneity, and grain size which also affect A will be included in this discussion. A (0) depends on sample shape. The theoretical function for A was derived originally for a flat surface.' In general we have found that a flat sample surface is readily obtainable." If such a surface can * The effect of surfaces which are not flat on the measurement of retained austenite will be discussed later. be obtained, it has the following advantages: 1—it is easily reproducible from sample to sample, 2—it is the form required for metallurgical examination —this type of examination being frequently desirable for this work, and 3—it is an efficient shape for diffraction purposes. Perhaps the most important of these features is that a flat sample surface is easily reproducible; hence, this requirement on the repro-ducibility of A from sample to sample is met for all such samples. Fig. 1—Schematic diagram of the quartz crystal monochromator diffraction unit. The centerline of the main beam is at 6' to the target face. The tangent to the crystal face is at 16.8' to the moin beam. The centerline of the monochromatic beam is at 33.6 to the main beam. The sample surface can be rotated in its own plane. The angle of the sample surface and the monochromatic beam can be adjusted by rotating about the vertical axis, The film holder can also be rotated about B so that the film can be exposed over the desired angular range. For Fe K, X = 1.932A. 1011 planes of quartz have d = 3.35A. A(0) depends on homogeneity and grain size. If the sample is badly segregated or the grain size is large, the effect of micro-absorption and primary extinction1. ' must be considered. It has been shown, however, that for most plain carbon or low alloy hardened steels, neither micro-absorption nor primary extinction effects are present.' A (0) depends on camera geometry. For a given angle 0, A remains theoretically constant from a geometrical viewpoint only if the following factors are kept constant: 1—the angle of inclination .+ of the sample to the X-ray beam, and 2—the centering of the sample with respect to the film cylinder. These are mechanical problems which can be solved readily if the facilities of a good machine shop are available. The arrangement used to insure that the angle 4 remains constant and the centering of the sample is reproducible is indicated schematically in Fig. 1. The sample is clamped against a thin plate with a hole in it by means of a spring-loaded pres-

Jan 1, 1954

The Development of Research and Quality Control in the Modern Steel Plant. By Leo F. Rein-artz. (Metals Technology, April 1943) Blast Furnace and Raw Materials Essential Considerations in the Design of Blast Furnaces. By A. L. Foell. (,Metals Technology, December 1942) Results Obtained from Surveys of Gas at Furnace Tops. By James M. Stapleton. (Metals Technology, January 1943) Physical Aspects of the Dust Catcher, Gas Washer and Precipitator on No. 3 Furnace at Carrie. By C. P. Clingerman and C. J. FleiscH. (Metals Technology, January 1943) Slag Control by Introduction of Flux through Blast-furnace Tuyeres. By Carl G. Hogberg (Metals Technology, January 1943) The Electrical Conductivity of Molten Blast-furnace Slags. By A. E. MaRtin and GerRard Derge. (Metals Technology, August 1943) Some Physical Characteristics of By-product Coke for Blast Furnaces. By CEarles C. Russell and MichaeL Perch. (Metals Technology, December 19+2) Pyrometry at the Coke Oven. By Robert B. Sosman. (Metals Technology, December 1942) Calcination Rates and Sizing of Blast-furnace Flux. By T. L. Joseph, H. M. Beatty and Gust Ritsianes. (Metals Technology, December 1942) The Low-temperature Gaseous Reduction of a Magnetite. By M. C. Udy and C. H. Lorig. (Metals Technology, October 1942) Steelmaking Problems of Total Operation in Steelmaking. By William C. Marshall and Frank G. Norris. (Metals Technology, April 1943) Silicon-oxygen Equilibria in Liquid Iron, By C. A. ZapFFe and C. E. Sims. (Metals Technology, September 1942) Equilibria of Liquid Iron and Simple Basic and Acid Slags in a Rolating Induction Furnace. By C. R. Taylor and John Chipman. (Metals Technology, September 1942) Rapid Analysis of Oxygen in Molten Iron and Steel. By Gerhard DeRGe. (Metals Technology, January 1943) Silver Chloride as a Medium for Study of Ingot Structures. By Karl L. Fetters and Margaret Dienes. (Metals Technology, August 1943)

Jan 1, 1943

The Development of Research and Quality Control in the Modern Steel Plant. By Leo F. Rein-artz. (Metals Technology, April 1943) Blast Furnace and Raw Materials Essential Considerations in the Design of Blast Furnaces. By A. L. Foell. (,Metals Technology, December 1942) Results Obtained from Surveys of Gas at Furnace Tops. By James M. Stapleton. (Metals Technology, January 1943) Physical Aspects of the Dust Catcher, Gas Washer and Precipitator on No. 3 Furnace at Carrie. By C. P. Clingerman and C. J. FleiscH. (Metals Technology, January 1943) Slag Control by Introduction of Flux through Blast-furnace Tuyeres. By Carl G. Hogberg (Metals Technology, January 1943) The Electrical Conductivity of Molten Blast-furnace Slags. By A. E. MaRtin and GerRard Derge. (Metals Technology, August 1943) Some Physical Characteristics of By-product Coke for Blast Furnaces. By CEarles C. Russell and MichaeL Perch. (Metals Technology, December 19+2) Pyrometry at the Coke Oven. By Robert B. Sosman. (Metals Technology, December 1942) Calcination Rates and Sizing of Blast-furnace Flux. By T. L. Joseph, H. M. Beatty and Gust Ritsianes. (Metals Technology, December 1942) The Low-temperature Gaseous Reduction of a Magnetite. By M. C. Udy and C. H. Lorig. (Metals Technology, October 1942) Steelmaking Problems of Total Operation in Steelmaking. By William C. Marshall and Frank G. Norris. (Metals Technology, April 1943) Silicon-oxygen Equilibria in Liquid Iron, By C. A. ZapFFe and C. E. Sims. (Metals Technology, September 1942) Equilibria of Liquid Iron and Simple Basic and Acid Slags in a Rolating Induction Furnace. By C. R. Taylor and John Chipman. (Metals Technology, September 1942) Rapid Analysis of Oxygen in Molten Iron and Steel. By Gerhard DeRGe. (Metals Technology, January 1943) Silver Chloride as a Medium for Study of Ingot Structures. By Karl L. Fetters and Margaret Dienes. (Metals Technology, August 1943)

Jan 1, 1943

By Ingersoll Olmsted

These ores are of two classes, Bessemer and non-Bessemer, existing in separate, though adjoining, beds. Both are carbonates, with small admixtures of oxides and other combinations. To prepare them for market they are roasted in kilns, which have already been described by Mr. John Birkinbine at the Troy Meeting, October, 1883 (Trans., xii., 378). Concerning their size, arrangement, etc., I need, therefore, only repeat that they are 60 feet in height; have wrought-iron shells 24 feet in diameter; are lined with fire-brick, and supported by cast-iron mantel and columns.

Jan 1, 1889

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Jan 1, 1907

By Robert Baschwitz, John Chipman

The distribution of silicon between liquid silver and Fe-Si-C alloys has been studied at 1420oand 1530°C. The data are consistent with earlier studies. New data of Hager on the liquidus lines of the system Ag-Si and the distribution data are used to obtain the activity coefficient of silicon in both liquid phases. Data on the heat of mixing in iron permit accurate extension to 1600°C. Equilibrium data involving SiO2 and silicon in liquid iron together with revised data on the free energy of SiO2 are used to fix the activity of silicon in the infinitely dilute solution. The binary system exhibits strong negative deviation from ideality. At infinite dilution ? Si at 1600" is 1.25 x 10'3, and at concentrations up to NSi = 0.4 the slope d InySi/dNSi has a constant value of r; = 13. It is found that logysi in the ternary solutzon is approximately but not exactly the same function of Nsi + NC as of NSi in the binary. The results are consistent with currently available data on the free energy of Sic and its solubility in molten iron. LIQUID solutions of the system Fe-Si-C have acquired considerable importance as the laboratory prototypes of blast furnace hot metal. Equilibrium studies involving such solutions and slags approximating those of the blast furnace have yielded useful information concerning the thermodynamic properties of blast furnace slags. In studies of this kind great importance attaches to a knowledge of the thermodynamic activity of silicon in the solution as a function of temperature and composition. An attempt was made by Chipman, Fulton, Gokcen, and askey' to evaluate all of the pertinent data on this system and to deduce the desired relation between activity, composition, and temperature. These authors published data on the solubility of graphite and Sic in molten Fe-C-Si solutions and on the distribution of silicon between liquid iron and liquid silver. They showed further how the activity of silicon in very dilute solutions in liquid iron could be calculated from equilibrium data involving the molten alloy and solid SiO,. These calculations rested on the published thermodynamic properties of SiO, in- cluding its heat of formation which at that time was recorded as -209.8 kcal. This value has been under suspicion for some time and has recently been replaced by the concordant results from two independent laboratories2,3 which place the heat of formation of a-quartz at -217.6 kcal. This revision necessitates a re-evaluation not only of the activity of SiO2 in slag but also of silicon in molten iron. It is the purpose of this paper, therefore, to recalculate the activity of silicon, and in furtherance of this objective to present new data on its distribution between liquid Fe-Si-C alloys and liquid silver. HEAT OF SOLUTION OF SILICON IN IRON In order to determine the effect of temperature upon the activity coefficient it is necessary to know the heat of solution of silicon in iron as a function of composition. This is found in the data of Korber and Oelsen4 shown in Fig. 1. The curve corresponds to the following equation, which is of a form suggested by Wagner:5 Here AH is the heat absorbed in kilocalories in forming one gram atom of molten alloy from its molten elements and the N's are atom fractions. The relative partial molal enthalpies of the components, each referred to its pureliquid state and defined as zFe = aFe - PFe and zsi = HSi — -psi, are shown graphically. At low concentrations zSi = -28.5 kcal, in agreement with Kijrber and Oelsen's computation. This is in good agreement with the value of -29.3 kcal obtained by Chipman and Grant6 using an entirely different method. ACTIVITY AT INFINITE DILUTION From the known free energy of SiO, it is possible to obtain the activity of silicon in dilute solution in liquid iron from equilibrium studies. The heat of formation of a-quartz is —217.6 kcal and the heat capacity and entropy data are given by Kelley and ~ing.' The free energy of formation of ß-cristo-balite at temperatures above the melting point of silicon is expressed by the following equation: Si(Z) + O2(g) = SiO2 (crist); AF" =-226,500 + 47.50T [I] The value of the deoxidation product for silicon [%Si] x [%O]2 at 1600°C according to Gokcen and chipmans is 2.8 x 10"5, in agreement with results of Hilty and Crafts.9 More recent works of Matoba,

Jan 1, 1963

By Virgil Miller, F. B. Petermann, S. F. Ravitz

The Cle Elum nickeliferous iron deposit is in Kittitas County, Washington, in a rugged, mountainous region about 23 miles north of the town of Cle Elum. The Biewett Pass deposit, which is similar in character and occurrence, is in Chelan County, about 18 miles east of the Cle Elum deposit. A more or less continuous ore zone may extend between the two deposits, since iron ore is reported to have been discovered at Iron Mountain, which lies directly between them. The ore probably was formed by meta-morphism of laterite resulting from Ieach-ing of serpentine derived from peridotite. It consists largely of magnetite grains distributed through a matrix of limonitic material containing a small amount of hematite and chromite. Many of the chromite grains have shells and inclusions of magnetite. The magnetite grains range in size from 1200-mesh to 1/4-in., the average size being 48 to 65-mesh; the chromite grains range from 20 to 150-mesh. The gangue minerals are olivine and serpentine with a small, amount of chlorite, and appear both as very thin bands in the ore and 's minute fragments in the limonitic matrix. The nickel is present as minUte inclusions of a nickel silicate mineral within the magnetite and gangue par- ticles, varying in size from 1500 to about 280-mesh. Detailed analyses of 3000-lb. lots of Cle Elum and Blewett Pass ore are given in Table I. TABLE i.—Analyses of Ore Samples Per Cent Ore from Constituent cle Elum' Blewett Pass Cr....................... 2.23 2-12 Ni...................... 1.43 0.9s Fe...................... 52.9 41.4 SiOz.................... 5.6 13.4 CaO.................... 0.3 0.8 MgO................... 4-1 7-5 AI2O3................... 7.0 2.g P...................... 0.022 0.034 S....................... O.O1 o.oa Mn..................... I.I 0.4 Ba..................... nil co..................... o.oa 0.02 CU..................... 0.02 0.03 As...................... 0.03 Au..................... nil Ag°..................... O.58 Pt...................... ml Fe++.................... 8.9 5-9 Fe+++.................. 44-0 35-5 « Ounces per ton, 1 sr,cte,so,","&&$ally absent: B, W, M~, T~, V, ~i, Bi, Pb. Sb. Sn. Be, In, Hg. Zn, Zr. Cd. Preliminary Tests Attempts to beneficiate the ore by ore-dressing methods, including various 'cornbinations of sink and float, tabling, jigging, flotation, and magnetic separation, were consistently unsuccessful. A wide variety of roasting and leaching tests were made on both raw and reduced ore, but in most of the tests little or no nickel was extracted, and in none did the extraction exceed 50 Per cent. No nickel could be volatilized as the carbonyl. by treating reduced ore with carbon monoxide. Fairly good sepa-

Jan 1, 1944

By Earl C. Herkenhoff

Publication of the article "The Flotation Behavior of Digested Asphalt Ridge Tar Sands" by R.J. Smith and J.D. Miller has confirmed and again spotlighted a most significant and important development in the field of tar sand and heavy oil mining. This is the ability to recover 95% of the bitumen in dry tar sands by a hot water process. The initial investigation by Miller and Sepulveda in early 1978. "Separation of Bitumen from Dry Tar Sands," was the first blockbuster. It is disappointing that there has been so little scientific and industry ackowledgement that the authors laid to rest the long entrenched belief that the sand grains had to be "water wetted" for a hot water process to be applicable. Dr. Miller and his researchers at the University of Utah used slightly different mineral dressing terminology in describing their process but it is essentially the old, established technique of high &lids attrition scrubbing at elevated temperatures with a conditioner or modifier, followed by dilution and froth flotation. Similar techniques were described in detail for other nonmetallic minerals in the mid-1940s by Stuart Falconer of American Cyanamid Co. The authors used a 15-minute "scrub" period (or in their terminology "digester step") at 73% solids and 95OC (203°F) in a 0.3 m solution of sodium carbonate-about 4 kg/t (8 lb per st) of tar sand. Flotation was at 10% solids. Obviously, the scrub is an expensive step with respect to energy input but the high recovery of bitumen appears to justify it. Two basic questions then arise: What are the effects of shorter scrubbing time, lower temperature, and less sodium carbonate? Would a two-stage approach be advantageous? That is, could you get the major proportion of the bitumen with a mild scrub and apply the high power and temperature only to the refractory portion? These variables should be evaluated. Apparently, all results were only for rougher flotation. What would the grade and recovery of bitumen be if multiple cleaner flotation steps were employed? We must concede that a 60.62% grade of bitumen leaves considerable room for upgrading. Finally, it should be noted by all executives who approve funds for heavy oil recovery schemes, most of which are variations of in-situ methods, that mining can yield a 95% recovery of bitumen. That is correct, 95%. Imagine what that does to the total barrels recovered from a heavy oil resource compared with the scrawny 30-35% maximum recovery we are getting now. The conclusion-let's mine heavy oil and tar sands.

Jan 1, 1983

The regular activities of the Institute are financed mainly by income derived from members' dues, from advertising in MINING ENGINEERING, JOURNAL OF METALS, and JOURNAL OF PETROLEUM TECHNOLOGY, and from the sale of publications to the public In addition, collateral activities and special projects are financed each year by means of income - from endowed funds controlled and administered by the Institute. An active effort is being made to increase the endowment funds of the Institute through a standing committee, of which Wilfred Sykes is Chairman, and of which the other members are N G

Jan 1, 1952

By Robert R. Turner

This paper discusses wet and dry primary autogenous and semi-autogenous grinding, including a description of the equipment and its mode of operation, testing and the scaling-up of test data. Lists of selected literature references are included.

Jan 1, 1982

Meeting of May 22, 1914.-President Thayer. announced the appointment of the following Committee on Arrangements for the San Francisco meeting of 1915: Charles W. Merrill, Chairman; F. W. Bradley, Abbot A. Hanks, S. B. Christy, and H. C. Hoover. President Thayer announced the appointment of the following Committee on Organization for the Utah-Nevada Local Section: R. C. Gemmell, Chairman; C. D. Blood, Lafayette Hanchett, Ernest Gayford; Duncan MacVichie, and George W. Riter. The President of the Institute offered $100, to be known as the "President's Prize," to be used as prizes for the best papers submitted by members of the Affiliated Student Societies, to be divided as follows: First Prize, $50; Second Prize, $30; Third Prize, $20. A committee, consisting of J. F. Kemp, Chairman; W. L. Saunders, and T. T. Read, was appointed to report on the conditions to govern the award. The President announced the appointment of the Committee on Mining and Milling Methods, the personnel of which is shown on a subsequent page of this Bulletin. The following were appointed on the Advisory Committee to the U. S. Bureau of Standards, to represent the manufacture of the various non-ferrous metals as indicated: Copper, F. L. Antisell; Nickel, David H. Browne; Lead, H. O. Hofman; Aluminum, J. W. Richards; Zinc, G. C. Stone. It was voted to hold a meeting of the Institute under the auspices of, the Iron and Steel Committee, the Committee on Petroleum and Gas, and the Committee on Coal and Coke, in Pittsburg, Pa., Oct. 8, 9, and. 10, 1914.

Jan 7, 1914

Jan 1, 1941

By R. S. McCaffery, D. E. Krause

There has been some discussion among blast-furnace operators regarding the relative merits of tuyeres of the converging type and tuyeres designed in an attempt to produce a diverging jet of air. An article1 on Progress in German Blast Furnace Practice indicates the interest in this subject abroad. This article illustrates a diverging type of tuyere which is shown here in Fig. 1A. The design appears to be rather poor as regards known properties of air flow. The adoption of this tuyere, the arlicle states, resulted in a decrease of blast pressure of about 4 Ib. per sq. in. and an increase of the output of the furnace. If the improvements mentioned are due entirely to the change in tuyere design, the subject of tuyere design seemed worthy of investigation and this paper is a report of such work. Because of the gain in efficiency brought about by the use of a diverging tuyere in the German plant, it was thought desirable to investigate the shape of the air streams issuing from various types of tuyeres to ascertain whether the gain was due to the tuyere itself or to the distribution of the air in the furnace. Since it is difficult to do experimental work on a full-sized furnace, or even on full-sized tuyeres, and because of the equipment available for the work, it was decided to carry out the work on scale models of tuyeres. Therefore, in this work, single tuyeres were used and the blast discharged into the atmosphere. The shape of the air stream was determined by means of a Pitot tube suitably supported in the air stream at various positions. The air was furnished by a Roots blower driven by a 10-hp. direct-current motor having field control, and capable of discharging 250 cu. ft. per min. with a pressure on the discharge of 4 in. of mercury. A modern blast furnace with 21-ft. hearth requires about 50,000 cu. ft. per min. of free air at from 16 to 23 Ib. per sq. in. pressure, depending upon the type of burden. This pressure is the total pressure required to force the air through the burden and through the tuyeres. Upon computation the pressure drop through the tuyeres is about 1 to 2 lb. per sq. in. By making the tuyeres to a one-fifth scale, and by using a pressure of 1.5 in. of mercury, the shape of the air streams should be

Jan 1, 1931

Jan 1, 1902

Executive SIDNEY J. JENNINGS, Chairman. GEORGE D. BARRON J. E. JOHNSON, JR. EDWIN LUDLOW ROBERT M. RAYMOND Membership KARL EILERS, Chairman LEWIS W. FRANCIS J. E. JOHNSON, JR. LOUIS D. HUNTOON ARTHUR L. WALKER Finance GEORGE D. BARRON Chairman CHARLES F. RAND BENJAMIN B. THAYER Library E. GYBBON SPILSBURY,1 Chairman ALEX C. HUMPHREYS3 GEORGE C. STONE2 J. H. JANEWAY4 BRADLEY STOUGHTON Papers and Publications BRADLEY STOUGHTON, Chairman

Jan 6, 1918

By Henry M. Howe

This paper gives the results of an investigation of the beha vior of the argentiferous cobalt-nickel arsenides of Temiskam-ing, Ontario, in roasting, made in the metallurgical laboratories of the School of Mines of Columbia University in the City of New York. The ore was kindly given by the owners of the La Rose and Trethewey properties at Cobalt, Ontario, and Mr E. J. Hall, Tutor in Assaying in Columbia University, has helped us much. I. Object of the Investigation. The object of the investigation was to learn: 1. The temperature at which the arsenic is most rapidly expelled ; 2. The thoroughness with which it is expelled by prolonged roasting at this temperature; 3. The effect of adding charcoal (a) near the end of the roast and (b) at. the beginning of the roast. II. Nature of the ORe. The important ores mined in the Temiskaming deposits are: native silver—with small amounts of dyscrasite (Ag,Sb), ar-gentite (Ag,S), pyrargyrite (Ag,SbS,)—smaltite (CoAs,), chlo-anthite (NiAs,) and niccolite (NiAs). Mispickel (FeAsS) and cobaltite (CoAsS) also occur in smaller quantities. The average composition of the ore shipped from this district for the first six months of 1905 was: silver, from 4.1 to 4.8 per cent.; cobalt, from 6.9 to 8.2 per cent.; nickel, from 3 to 4.7 per cent.; and arsenic, from 30.9 to 34.6 per cent. The ore which we treated consists chiefly of smaltite. In our 1aboratory-work

Jan 1, 1908

By YANG TSANQ WOO

THE method of making coke that has been adopted at the Kaiping and other collieries in northern China resembles, to some extent, the familiar bee-hive oven process of the United States, except that a kiln with permanent sides is used instead of a closed oven, and the products of combustion are drawn off at the bottom, In building coke-kilns in China, two circular holes, 8 ft. 6 in. in diameter at the bottom and 13 ft. in diameter at the top, are excavated in the ground, both being .connected at the bottom by a flue as shown in Fig. 1. The sides and bottom of the kiln are lined with fire-bricks, and covered with a layer of fire-clay, and a rectangular opening, 6 in. by 8 in., connects the bottom of each kiln with the main flue. Around the edge of the hole, and overlapping the lining, is a wall of fire-brick extending .2 ft. 6 in. above the level of the ground. An open space 5 ft. wide is left in this wall, through which the coal is carried into the kiln and the resultant coke removed. This space, of course, is bricked up during the time that the coking operation is being carried on. The wall is pierced with nine flue-openings uniformly placed around the circumference, each intervening space in the wall being strengthened with a brick buttress, as is shown in Figs. 2 and 4. The floor of the kiln, as well as the main flue, is lined with fire-brick. Before charging the coal, it is first placed in shallow bamboo sieves, 2 ft. in diameter, and immersed in a trough 10 ft. long, and 3 ft. wide, fed with pit-water; in which it is washed by hand. Fig. 3 shows the manner in which the washing is done. From 25 tons of good " dust" coal, 22.5 tons of washed coal are obtained. When ready to charge the coal into the kiln a temporary cone-shaped flue of fire-wood and lump coal is first built to a

Nov 1, 1905

By Rollin E. Hook, Attwell M. Adair

The response of CrzO3 and C~304 to various heat treatments was studied in are-melted iodide chromizim over the temperature range 1000" to 1750°C. These oxides, which are present as impurity phases in this material, were identified by X-ray diffraction teclzniques which were supplemented by optical metallop-aphy. As a function of increasing temperature, Crs04 is first observable in samples annealed at 1300°C and coexists with Cr2O3 (the low-temperature oxide) over a temperature range exceeding 200°C. As the temperature decreases, Cr3O4 dissolves with the concomitant precipttation of Cr2Y2. Both oxides precipitate predominantly at pain boundaries. The reactions which occur are involved with at least ternary equilibria, possibly due to iron which is present as an impurity in arc-melted iodide chromium. HILTY, Forgeng, and Folkman' reported in their investigation of the Fe-Cr-0 system that Cr3O4 (with about 8 pct Fe substituted for chromium) is a primary phase found in alloys with 9 or more pct Cr. They reported that this phase is stable only at high temperatures and that below the liquidus Cr3O4 is disproportionated into Cr2O3 and chromium-rich metal for both Fe-Cr-O alloys and in oxygen saturated pure chromium. Further, they proposed that CrsO4 forms by a peritectic reaction between Cr2O3 and the liquid. On the other hand, Hook, Garrett, and Adair2 found in their investigation of impurity phases formed in "pure" chromium (material consolidated from iodide chromium crystals) that Cr3O4 forms intergranularly and is stable as low as 1500°C which is 375OC below the melting point of chromium. The purpose of the research described herein is to determine the temperature range of stability of Cr3O4, and to show the nature of its decomposition. This further investigation indicates that Cr3O4 undoubtedly occurs in this material as low as 1300°C. The chromium studied was consolidated and fabricated from iodide chromium crystals (ICr-5) and contained Fe r 135 ppm, Si = 20 to 100 ppm, and 0 = 35 to 137 ppm. A complete chemical analysis is given elsewhere.' Annealing was conducted in 1 atm of purified helium and all samples were rapidly cooled (-200°C per sec) by withdrawing them from the furnace hot zone under a high flow rate of helium. The details of the electrolytic-etching technique and electrolytic-digestion techniques for preparation of insoluble residues for X-ray examination are given elsewhere also.' EXPERIMENTAL RESULTS The Starting Material. The as-swaged rod (final swaging done at 900°C) had a wrought grain structure and contained a dispersion of CrzO3 inclusions of maximum particle size of about 2 or 3 p, Fig. 1. The microstructure also contained a dispersed

Jan 1, 1964

By Pieter W. Greeff, Graeme W. Mitchell

INTRODUCTION This paper describes the underground environmental planning parameters developed for Pancontinental Mining Limited's Jabiluka uranium deposit. The deposit is located 230 km east of Darwin in the Alligator Rivers region of the Northern Territory, Australia. The deposit is situated within land subject to an Aboriginal land claim, adjacent to a National Park and within a proposed extension to that National Park, as well as being close to a long- established Aboriginal reserve. In addition, being the first large underground uranium mine planned in Australia, the environmental considerations, both on surface and underground are considerable. Pancontinental is committed to the highest practicable standard of environmental management in the operation of the mine. In addition, Government regulations and requirements are particularly stringent by world standards. The underground environmental problems are discussed later in the paper with emphasis placed upon radiation aspects, both gamma and radon daughters, and dust. Consideration has also been given to heat and humidity due to the location of the deposit in a sub-tropical region 12° south of the equator. The paper explains how these environmental factors influence the design and selection of stoping methods. GEOLOGY AND ORE RESERVES The Jabiluka Two orebody is completely overlain by flat-bedded Kombolgie Sandstone with a thin layer of surficial colluvial sands. The orebody occurs in an east-west striking folded succession of Lower Proterozoic metasedimentary rocks of the Cahill Formation. Uraninite and pitchblende constitute essentially all the uranium mineralisation and are contained in the four lithological series, as shown in Fig. 1. - ,Upper Graphite Series - Main Mine Series - Lower Mine Series 1 - Lower Mine Series 2 The succession at Jabiluka has been folded and forms an east-south-east striking, asymmetric syncline-anticline which dips south and plunges to the east. A major fault bisects Jabiluka Tw8 having a north-south trend and dipping about 80 to the west. A near vertical tourmaline granitic pegmatite dyke up to 30 m in thickness has intruded the Jabiluka Two orebody at the western end. Current drilled ore reserves for Jabiluka Two are 52.0 million tonnes at 0.39% U308. Included in these reserves are 1.1 million tonnes of gold ore at 10.7 g/tonne. A large proportion of the orebody can be mined in thick sections (over 80% of tonnage) either as single sections or by bulking a number of thin sections which are close together.

Jan 1, 1981

By R. Wild, F. A. Wright

When a blast furnace has a certain defined burden and is operated under fixed conditions of blast temperature, etc., the fuel efficiency is determined by the extent to which the reducing gases can remove oxygen from the burden in the furnace stack. This is determined by two distinct factors: 1) The uniformity of gas-solid contact, and 2) The ease with which oxygen can be removed from individual pieces of burden. This latter is often called burden reducibility. When burdens were poorly prepared the first factor was by far the most important and a study of the reducibility of individual lumps was of rather academic interest. In recent years good burden preparation with emphasis on uniformly sized material has led to greatly improved gas distribution in the stack, and thus the second factor has become much more important and there has been a marked increase in interest in methods of measuring reducibility. This paper explores the Linder method of measuring such reducibility. The measurement of reducibility of burden materials must be carried out under conditions duplicating, as nearly as possible, those of the blast furnace stack. This is very difficult since the blast furnace process is a counter-current one, and thus the initial conditions encountered by the solid (gas temperature, composition, etc.) are the result of heat and mass transfer occurring lower down the stack. Any method of burden testing which does not take this into account is, at least to some extent, based on arbitrary assumptions. In an attempt to study blast furnace reactions under non-arbitrary conditions BISRA adopted the SCICE technique as a method of investigation. This technique has been used with a measure of success.' The SCICE technique, however, was found to be too slow for use as a routine test for burden materials and it was decided to construct additional equipment for burden testing. A test was required which would: 1) Be as realistic as possible. 2) Be quick and easy to operate. 3) Give some indication of the breakdown likely to take place during reduction in addition to a reducibility index. After a critical assessment of the reducibility tests which have been proposed it was decided to adopt the Linder test equipment and procedure as a basis for burden testing. THE LINDER TEST APPARATUS AND PROCEDURE The apparatus which was constructed (Fig. 1) was the same as that described by Linder2 except for minor changes in design. Linder also laid down a test procedure which he had derived from the results of investigations on Swedish blast furnaces. The variations of temperature and gas composition during the test were defined; these are shown diagram-matically in Fig. 2. BISRA's intention was to use the standard temperature and gas composition programmes for testing a variety of burden materials and also to investigate the influence of different programmes on standard burden materials, making use of information from the SCICE apparatus wherever this is possible. Up to the present, effort has been concentrated on the first part of the programme, and work on the second part has only just commenced. For each test 200 g of coke and 500 g of burden material were used. Linder had recommended that the coke and burden material should be between 1 and 1 1/2 in. and this was adhered to in early experiments on ores and sinters. Since the eventual aim of this work was to relate the test results to blast furnace operation, it was decided to carry out subsequent experiments using burden material in the size range used in the blast furnace, as far as this was possible. If the main interest was, for example, a comparison of the products resulting from different methods of agglomeration, then there would be advantages in using burden materials as close as possible to a standard size. After the charge had been placed in the reaction tube and this had been connected to the gas supply, rotation of the reaction tube at 30 rpm was started and the reduction programme was commenced, the gas temperature and composition being manually controlled according to the programme shown in Fig. 2. After the reduction test the charge was cooled in a nitrogen atmosphere. It was then removed from the reaction tube, the coke and burden separated, and the extent of burden breakdown assessed by screening it at 10 and 30 mesh. The extent of reduction was then

Jan 1, 1964