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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 following is an incomplete list of members and guests who called at Institute headquarters during the period July 10, 1919, to Aug. 10, 1919. Howard C. Arnold, Washington, Pa. J. S. Lane, New York City, N. Y. L. M. Banks, Denver, Colo. H. W. Lawrie, Washington, D. C. George S. Blair, Pittsburgh, Pa. J. L. McAllen, Latouche, Alaska. Richard H. Catlett, Newark, N. J. David F. McFarland, Urbana, Ill. George L. Clark, Council Bluffs, Iowa. James F. Magee, Lancaster, Pa. Capt. Frederick S. Cook, Portland, Ore. A. G. McGregor, Warren, Ariz. John J. Croston, Atlanta, Ga. Emory M. Marshall, Santa Fe, N. M. Thomas Davis, Seattle, Wash. Benjamin L. Miller, Bethlehem, Pa. J. C. Dick, Salt Lake Cite, Utah. 2d Lieut. C. 0. Noble, U. S. Army. Chris. G. Dobson, Vancouver, B. C. Irving Perrine, Hutchinson, Kans. H. S. Emlaw, Grand Rapids, Mich. Fred S. Porter, Seattle, Washington. F. A. Fahrenwald, Cleveland, Ohio. Capt. H. R. Robbins, Peking, China Lieut. James L. Head, St. Louis, Mo. Joseph P. Ruth, Jr., Denver, Colo. A. A. Holland, Napanu, Canada. William A. Simkins, San Francisco, Calif. W. E. Hopper, Washington, D. C. T .V. Smirnoff, Siberia. Harry Hotchkin, Chicago, Ill. Harrison Souder, Cornwall, Pa. L. L. Hutchison, Tulsa., Okla. F. J. Sur, Denver, Colo. Paul S. King, Wilmington, Del. Harry Wolf, Denver, Colo. George K. Anderson, Jr., lies accepted a position as manager for Wight & Co., producers of air-cooled blast-furnace slag, at Longdale, Va. J. M. Armstrong, with the Caribbean Petroleum Co., has been transferred from Philadelphia to Maracaibo, Venezuela. Fred Sherman Baker, who has been with the Oriental Consolidated Mining Co., at Unsankinko, Chosen, Korea, is now at Columbia City, Ind. Ray J. Barber has removed from Roxbury, Mass., to New York City, and is now consulting engineer for the Roxbury Cold Mines, Inc.

Jan 9, 1919

By C. W. Sherman, N. J. Grant

The correlation of the high temperature chemical properties of slag-metal systems with some easily measured property of either slag or metal at room temperature has been the goal of both process metallurgists and melting operators for many years. There are several rapid methods for estimating various constituents in steel in addition to the conventional chemical methods which are quite fast, but these do not reveal the nature of the slag as a refining agent, which is of primary interest to the steelmaker. Furthermore, there are several methods for examining slag, the three principal ones being slag pancake, petrographic examination, and the previously mentioned chemical analysis. The main objection to the last two is the lime required to make a satisfactory estimate of the mineralogical or chemical components. The objection to the first is the inadequacy of the information obtained. A new technique has been developed by Philbrook, Jolly and Henry1 whereby the properties of slags are evaluated from an aqueous solution leached from a finely divided sample of slag. It is known that the pH or hydrogen ion concentration (of saturated solutions that have dissolved certain basic oxides, notably calcium oxide) will indicate a pronounced basicity. Philbrook, Jolly and Henry devised the pH measurement technique in order to supply open hearth operators with a fast, reasonably accurate method of estimating slag basicity. They offered the method as an empirical observation and made no claims as to its theoretical justification. The results were presented as an experi-metally observed relationship which applied over an important range of basic open hearth slags. They found that, in plotting the measured pH against the basicity, the best relationship existed between the pH and the log of the simple V ratio, CaO/SiO2. Extensive investigation also showed that there were several variables in the experimental technique that influenced the results and necessitated following a standard procedure to obtain reproducible pH readings. These variables were: 1. Particle size of the slag powder used. 2. Weight of sample used per given volume of water. 3. Time of shaking and standing allowed before the pH was measured. 4. Exclusion of free access of atmospheric carbon dioxide to the suspension. 5. Temperature of the extract at the time the pH was measured. In subsequent investigations of the pH method by Tenenbaum and Brown2 and by Smith, Monaghan and Hay3 the general conclusions of Philbrook's work were reaffirmed. It was the object of the present investigation to extend the technique to a point where it could be used to evaluate slags of all types. Experimental Results PARTICLE SIZK OF SLAG POWDER A large sample of commercial blast furnace slag of intermediate basicity (V-ratio 1.15) was selected for the study. The slag had been put through a jaw crusher until all of it passed through a 20 mesh screen. Five fractions of this crushed material were separated, -20 to +40, -40 to +60, -60 to +100, -100 to +200, and -200 mesh. A representative sample of 0.5 g was removed from each fraction and the pH determined using the method of Philbrook. Check pH analyses on the sample fractions varied due to the different amounts of shaking. To eliminate this variable, a mechanical shaker was employed. In order to know the exact time of contact between the slag and water, it was found necessary to filter the extract at the end of the shaking period. Using the mechanical shaker and a filtering apparatus, similar runs were made on the five fractions for contact times of 5, 10, 20, and 40 min. Random checks gave reproducible results within 0.02 pH. The data are plotted in Fig 1. It can be seen from the plot that each slag fraction is hydrolyzed to an extent that is roughly proportional to the surface area exposed to the water. The (—100 to +200) mesh material changed very little in pH after 10 min. shaking time. The curves are symmetrical and lie in proper relation to one another. The —200 mesh curve appears to be somewhat flatter than the others, but this can be attributed to the portion of very fine material that is not present in the other fractions. The closeness of the (-100 to +200) mesh curve to the —200 mesh curve and the fact that a —100 mesh sample would contain amounts of slag down to 1 or 2 microns in diam were considered sufficient reasons for selecting a —100 mesh sample as representative of the whole sample of slag for the purposes of this investigation.

Jan 1, 1950

By Persifor Frazer

(Read at the Amenia Meeting, October, 1877.) IT has been the aim of the writer, by measuring his base line on the territory of theoretical chemistry, to attempt to fix by triangulation certain points within the domain of mineralogy. As the barest first experiment in this direction, a few of the hydrated oxides of iron have been selected, their theoretical construction reduced to percentage of the constituents into which the ordinary analytical methods would resolve them, and the results compared with actual analyses compiled from the most reliable sources; the accidental errors being as much as possible eliminated. This method seems to be a simple one and one easily pursued, but, as will shortly appear, it is beset with grave difficulties, all of which the writer does not pretend to have satisfactorily surmounted. In the first place arises the important question, what are we to understand by the hydrated oxides of iron ? In all books of chemistry and lexicons of minerals, the proposition, long ago taught by the earlier chemists, that water might exist in two forms of combination, viz., as water of crystallization or as water of constitution, is tacitly assumed. There is nothing in the principles of the new chemistry which is opposed to this ; for (to carry the mind's eye into .the process of construction of the least units into which a definite chemical compound is capable of being divided without losing its characteristic properties), however unlikely it may seem, it is, nevertheless, possible that a given molecule of iron may, under certain conditions of heat, pressure, etc., attract to itself as many molecules of the water in which it is natant as from the relative size, shape, attractive force, etc. of either, it is capable of taking up, and this complex system of associated molecules might oscillate as a physical unit so long as the conditions on which its existence was dependent remained unchanged. Moreover, it is highly probable that the first effect upon such a molecule produced by physical or chemical forces would be to separate it into two or more simple ones of different kinds, while a further application of these forces might rend asunder the bonds of the simpler compounds themselves.

Jan 1, 1878

By Persifor Frazer

It has been the aim of the writer, by measuring his base line on the territory of theoretical chemistry, to attempt to fix by triangula tion certain points within the domain of mineralogy. As the barest first experiment in this direction, a few of the hydrated oxides of iron have been selected, their theoretical construe tion reduced to percentage of the constituents into which the ordinary analytical methods would resolve them, and the results compared with actual analyses compiled from the most reliable sources; the accidental errors being as much as possible eliminated. This method seems to be a simple one and one easily pursued, but, as will shortly appear, it is beset with grave difficulties, all of which the writer does not pretend to have satisfactorily surmounted. In the first place arises the important question, what are we to understand by the hydrated oxides of iron ? In all books of chemistry and lexicons of minerals, the proposition, long ago taught by the earlier chemists, that water might exist in two forms of combination, viz., as water of crystallization or as water of constitution, is tacitly assumed. There is nothing in the principles of the new chemistry which is opposed to this; for (to carry the mind's eye into the process of con struction of the least units into which a definite chemical compound is capable of being divided without losing its characteristic proper ties), however unlikely it may seem, it is, nevertheless, possible that a given molecule of iron may, under certain conditions of heat, pressure, etc., attract to itself as many molecules of the water in which it is natant as: from the relative size, shape, attractive force, etc. of either, it is capable of taking up, and this complex system of associated molecules might oscillate as a physical unit so long as the conditions on which its existence was dependent remained unchanged. Moreover, it is highly probable that the first effect upon such a mole cule produced by physical or chemical forces would be to separate it into two or more simple ones of different kinds, while a further ap plication of these forces might rend asunder the bonds of the simpler compounds themselves.

Jan 1, 1879

By Walter Crooke

Regenerative hot-blast stoves are now in general use in all parts of the world, and are so well understood and appreciated, that I need not take up your time with an account of their history and introduction into the United States. My object in writing this paper is to give you a short description of a stove that is now being very favorably received and adopted here (see drawing). The stove was first introduced into this country in 1887 by M'Clure & Shuler (now M'Clure & Amsler), who have the management of the patent right in the United States. The English design had to be modified to suit the exigencies of American blast-furnace practice, which, in many respects, widely differs from our English experience. In the first place, the fire-bricks used in America expand to an extent unknown in England, and it became necessary to make special provision for this by increasing the number of cross-walls, and by leaving a space at the top of the stove through which the lining could expand. The expansion laterally was, however, more difficult to provide for, as the combustion-chamber in the center, being the hottest part of the stove, must necessarily expand more than the outer walls, and therefore tend to squeeze up the flue-openings. On first introducing these stoves to American ironmasters, a feel ing seemed to prevail that a " four-pass " stove did not utilize the whole of its surface. They also had an idea that the " two-pass " stove let the burning gas go before all the duty had been extracted from it; so that it was found neceseary to design a stove of a special character to suit their wishes. Hence the "three-pass" chimney top stove now before your notice, the advantage claimed for which is that each stove is independent, requiring no underground chimney flue or stack, and can be erected at a very light cost. The working of these stoves has proved to be very successful wherever they have been introduced.

Jan 1, 1891

By Martin Epner, Eric Gregory

DURING the past decade, considerable work has been carried out on various cermet systems in an effort to produce materials suitable for high-temperature applications in gas turbines. Most of the materials have not, as yet, met the requirements of the engine manufacturers, primarily because of their lack of room-temperature ductility and thermal shock resistance. In the field of tool materials, however, although ductility is still of prime importance, much has been accomplished by improving design parameters and the quality of carbide materials with a view to using cermet compositions successfully. The systems described in this paper were designed primarily for application in this field, although their development was a natural outcome of work on similar compositions designed for high-temperature service. In steel-bonded titanium carbide, the steel binder imparts heat treatability to the system while the carbide provides abrasion and wear resistance. Combining the carbide and the steel matrix in carefully controlled proportions results in a composite material which, when the steel is hardened, has man of the properties of cemented tungsten carbide. In the annealed condition, this material can be readily machined by the conventional chip-removal techniques. Titanium carbide has certain distinct advantages over many of the other carbides when combined with a steel matrix. It is among the hardest of the carbides and is one of the most stable. Liquid iron wets titanium carbide, and this wetting assists in the formation of a dense cermet. Once the composite structure has been formed, the titanium carbide acts as a relatively inert phase during the heat treatment of the matrix. PREPARATION OF ALLOYS The steel-bonded titanium-carbide materials described in this paper were prepared by the liquid-phase sintering technique. The titanium carbide used had an average particle size of 6 to 7 p, a total carbon content of 19.4 pct and 0.35 pct free carbon. This was blended with the elemental metal powders by ball milling them together in a hexane medium. After drying, paraffin wax was added to the blend to provide green strength in the pressed briquettes, and compacting was performed at 15 tsi. Liquid-phase sintering was carried out in vacuum at temperatures which depended on the chemical composition of the system involved, but which were usually around 2640° F. The resultant materials had a density approaching 100 pct of theoretical. The

Jan 1, 1961

By H. E. Nold

THIS paper is an effort to explain in a simple manner the fundamental principles involved in examining a clay deposit for both quantity and quality and in operating a clay mine, either open-pit or underground, SO that the best quality of finished material can be made from the raw material available. The writer is aware that what is recommended in this paper is everyday practice in many refractories plants and in some other heavy-clay products plants, but observations made while visiting practically every clay mine in Ohio have convinced him that the practices herein discussed are not as widely used as their importance warrants. It is true that the problem of mining for quality is more acute in refractories plants than in most heavy-clay products plants, yet some of the latter are finding it profitable to pay more than ordinary attention to the selection and blending of their raw materials. It is hoped that this short paper may prove helpful to some who are now finding it difficult to produce a uniform product of as high quality as their clay deposit seems to warrant. The coordination of the work of the clay mine or pit with the manufacturing plant, to the end that the best product possible be made from the raw material available, presupposes a rather intimate knowledge of the clay deposit. The knowledge must include not only information of the amount of clay available but also rather detailed information about both vertical and horizontal variations in quality of the clay. This information should cover three things: quality, quantity, and location. Sampling Undeveloped Deposits In the case of an undeveloped deposit with a shallow overburden, pitting may be the cheapest way of testing. For thick deposits or deposits with rather heavy overburden, the diamond drill, using a double core barrel, offers the best means of testing. When using the diamond drill in clay testing, it is doubtful whether it pays to take less than 2-in. cores; it is difficult to get complete cores with smaller drills, and the quantity of material obtained with smaller cores is not sufficient for the necessary tests.

Jan 1, 1929

Resistant Tape A new oil-resistant tape for rapid insulation build-up on splices in large power cables has been announced by Minnesota Mining & Mfg. Co. Designated Scotch brand electrical tape No. 25 is made of synthetic rubber providing greater dielectric strength and resistance to high temperatures. The chemical-resistant qualities of the tape make it suitable for use in oil drilling, mining and underground [ ] cable operations, while the 40-mil thickness and extreme stretch (1500 pct breaking point) make possible smooth insulation wraps on irregular surfaces. Dielectric strength is 15,000 v and 10,000 v at 500 pct elongation. It has an electrolytic corrosion factor of 1.0 and an insulation resistance of 100,000 megohms. Circle No. 1 Hydra-Lift The Pitman Mfg. Co. announces that is now has in production a new model of the Pitman hydra-lift, recently-developed crane with hydraulically-powered boom that can be mounted on the frame of any truck, 1 ½ tons or larger. According to the manufacturer, the new model hydralift model B features a variety of improvements over the original production model, introduced late in 1950. Changes incorporated in the new model, according to officials, not only have resulted in improved crane, but also have given the unit a new profile which distinguishes it sharply from the original model. The two chief improvements in the new model are: a big increase in the unit's safety margin and the fact that it is now shipped almost completely preassembled, cutting the time and cost of installation. Rated capacities of the hydra-lift are based on the tipping factor of a 1 1/2 ton truck, with outriggers down, and thus have not been increased. Circle No. 2

Jan 1, 1952

By Frank G. Snyder, Paul E. Gerdemann

The Southeast Missouri lead district, located about 70 miles south of St. Louis, embraces four important sub-districts and several minor ones. The important sub-districts, in order of discovery, are Mine La Motte, the Old Lead Belt, Indian Creek, and the Viburnum Lead Belt. Descriptions that follow are of geology and ore deposits of the Old Lead Belt. The ore deposits are stratiform in character and are localized in a narrow carbonate bar and algal reef environment on the flanks of exposed Precambrian of the St. Francois Mountains. Ore structures include a variety of primary depositional features such as pinchout zones, disconformities, ridge structures, reefs, and submarine gravity slides. Faulting, prior to and during ore deposition, "prepared" the host rock and strongly fractured areas are mineralized much more intensively and extensively than unfractured parts of the same sedimentary structures. The deposits are epigenetic in character. Mineralization is believed to have occurred at the time that post-lower Ordovician faulting took place. The mineralizing solutions are believed to be concentrated brines from adjacent basins that moved out of the basins during faulting, uplift, and erosion of the St. Francois positive area.

Jan 1, 1968

By L. C. Armstrong

Twice in the past two years and in two widely separated localities-one near Williamsville, Mo., and the other in the Allard Lake district of Quebec- the Contract Drilling Division of the Longyear Company has experienced perplexing difficulties in drilling granitoid igneous rocks. The rocks in both places are characterized by appreciable amounts of feldspar intimately intergrown with quartz particles of microscopic dimensions. The disappointingly slow rate of advance and the exceptionally high bortz loss, obtaining during the life of these two projects, are ascribed largely to the resistance to abrasion of these two minerals when arranged in this intergrown pattern. Whether all intergrowth-bearing igneous rocks would offer extraordinary resistance to bit progress cannot be stated with assurance on the strength of these experiences alone. More data on diamond drilling this sort of material in a number of localities are needed before any generalizations can be made safely.

Jan 1, 1949

T. R. HARRISON, Washington, D. C. (written discussion). *-Mr. Kowalke shows that a high resistance millivoltmeter is subject to smaller errors, due to change in resistance of the thermocouple to which it is attached, than is a low-resistance instrument. He uses as examples instruments having resistances of 30 and 2 ohms, respectively. At the Bureau of Standards, resistances above 300 ohms would be considered high and 30 ohms rather low. In the tests on calorized-iron thermocouples, a difference between the first and third calibrations of the couples serves to show changes due to the intermediate heat treatment and only under certain conditions would changes in calibrations due to changes in the wire be detected by ,a recalibration after 1 1/2 in. had been cut from the hot-junction end of the couple and the ends rewelded. The calibration of a couple depends only on the thermoelectric prop-erties of that part of the couple which lies within the region of non-uniform temperature, i.e., the temperature gradient; hence, so long as the temperature gradient falls along wires of similar thermoelectric properties no change in the electromotive force is produced by altering the metals of those parts of the circuit that are at uniform temperature. Usually at the cold-junction end of the circuit, copper leads, brass binding posts, manganin resistance coils, and various other materials form part of the circuit, but so long as all are at a uniform temperature (or if for each junction between unlike metals there is a similar opposing junction at the same temperature) no resultant thermoelectromotive force will be produced thereby. Likewise, if a length of several inches at the hot-junction end of the couple is at uniform temperature, it matters not if this section is unlike other parts of the couple, so long as there is good metallic connection and no source of e.m.f. other than thermoelectric is present. Cutting off part of the hot end of the couple within such a region of uni-form temperature would not alter the e.m.f. of the couple.

Jan 12, 1919

By H. Case Willcox

AERIAL photographic surveying and mapping is not new or unknown to geologists. However, it has been utilized but little before, principally because it is only within the last few months that practical means of adapting this method to the requirements of petroleum companies have been discovered. No American aerial survey company has taken up aerial surveying and mapping as an engineering service to be offered to petroleum companies and their geologists for use in undeveloped and jungle-covered petroleum areas. This method of surveying and mapping, however, is used by the War Department, the U. S. Reclamation Service, and Geological Survey, and the corresponding Departments of the Canadian Government. ADVANTAGES OF AERIAL PHOTOGRAPHIC SURVEYING AND MAPPING The advantages of aerial photographic surveying and mapping to petroleum companies and their geologists are many. One of the most valuable is presented in the very first phase, or the exploration period. It is assumed that, when convinced that petroleum possibilities are present, a petroleum company has secured a concession of 8000 sq. mi. of unexplored area in Eastern Venezuela. The company may either have the entire area surveyed and mapped by the aerial photographic method, or send its chief field geologist up in an airplane so that he, from-an aerial reconnaissance, may reject certain portions that, for geological reasons, the company would not be interested in. He will then point out the regions that are to be surveyed and mapped. After the air-work is completed, the results are brought down, developed, and printed; then the resulting "contact prints" are given to the field geologist. They may be roughly assembled to give a general idea of the property in its entirety, or they are in shape to be examined in adjoining pairs under the stereo-scope. With this instrument, the geologist is enabled to make a minute examination of surface indications. The work of assembling and constructing a complete general or detailed map, according to the scales desired by the petroleum company and for the later office use, is continued by the aerial photographic company.

Jan 3, 1925

By Harold Price

PRIOR to Sept. 1, 1928, there had never been constructed what might be termed a long pipe line with electric-welded field joints. Nevertheless, by Sept. 1, 1929, within the period of a year, more than 2500 miles of electric-welded lines have been completed. These lines vary in diameter from 6 to 20 in., and in length from 50 to 700 miles. Before Sept. 1, 1928, no such line had been constructed .longer than 50 miles, and only one of nearly that length, a 40-mile 7-in. gas line in Louisiana. This was in reality the first pipe line to use electric-welded field joints. During the past year the following lines have been electric-welded by the Welding Engineering Co. alone: Texas Pipe Line Co.-157 miles of 8-in. line from Corsicana, Texas, to San Augustine, Texas. (This was the first electric-welded oil line.) Texas Pipe Line Co.-80 miles of 8-in. from Lafors, Texas, to Childress, Texas. Texas Pipe Line Co.-39 miles of 10-in. from Monahans, Texas, to Jal, New Mexico. Texas Pipe Line Co.-50 miles of 6-in, from San Antonio, Texas, to San Marcus, Texas. Texas-Empire Pipe Line Co.-424 miles of 12-in. from Cushing, Okla. to Chicago, Illinois. In addition to the field welding mentioned above,1 250 miles of 12-in. line was electric-welded into double joints at the pipe mill at Indiana Harbor, Ind.

Jan 1, 1929

By Leonard Larson

Before direct or wet smelting of copper concentrate was adopted at the McGill smelter, in November 1932, actual furnace smelting tests had indicated the possibility of smelting between 400 and 500 dry tons of wet concentrate per furnace day. Under calcine smelting practice, solid charge up to 116; tons per furnace day had been smelted. It was realized that in order to smelt wet tonnage in equivalent amount per furnace day, a higher combustion rate and higher temperatures would be necessary within the furnace. The reverberatory furnace considered in the following history of wet-smelting developments is a unit rz7 ft. long and 28 ft. 8 in. wide, inside dimensions (Fig. I). This furnace was in operation through all the years from 1934 to date. During 1933, the first complete year of direct or wet smelting, the plant was on a curtailed copper-production basis and the available concentrate tonnage to be smelted was limited. The average coal-firing rate in the reverberatory for that year was 124 tons per furnace day. This rate was lower than the average for years immediately preceding under calcine smelting practice. With this coal-firing rate, an average of 391 tons of new metal-bearing material (N.M.B.M.) was smelted per furnace day. The following year, 1934, the coal-firing rate was increased to 139 tons and the smelting rate increased to 448 tons N.M.B.M. per fur- nace day. In succeeding years production required that either more tonnage be smelted in the one furnace or an additional furnace be placed in operation. With this situation confronting the smelting department, it was determined to continue the program of increasing the coal-firing rate and also to intensify the temperature in the smelting zone of the furnace. In order to accoinplish this, various improvements were made to aid combustion within the furnace. The burners were enlarged, increased primary air was supplied to the burners, and changes were made in the furnace to enlarge and streamline the outlet, thus increasing the furnace draft. The coal-firing rate was increased yearly until 1937 when the firing rate averaged 210 tons per furnace day. Thereafter the firing rate fluctuated according to character of charge and production requirements. In general, however, with the same character of charge the smelting rate increased in almost direct proportion to the increases in firing rate. Table I shows the average coal-firing rate, smelting rate, and other pertinent data for the direct-smelting years of 1933 to 1939 inclusive, the first fivc months of 1940 and May 1940. These figures show that the water evaporated in the waste-heat boilers was in almost direct proportion to the coal-firing rate. In making comparisons in the table, it should be borne in mind that the figures, except for May 1940, are yearly averages. Because of changes in character of charge or operating conditions, records for individual days or even months

Jan 1, 1944

By HENRT M. HOWE

IN my original paper, Piping and Segregation in Steel Ingots, I pointed out1 among other things that, in view of the slighter stretching (virtual expansion) of the crust, and greater opportunity for sagging, there should be less piping in broad than in narrow ingots, and less in slowly-cooled ingots, e.g., those cast in pre-heated sand molds, than in those which cool quickly, e.g., those cast in iron molds. A. A. Stevenson2 said that neither of these predictions agreed with his own experience. In particular, in a picture which he showed of a wide and of a narrow ingot cast from the same ladleful of steel,, the wide ingot had certainly piped much more deeply than the narrow one. At the time I did not see the explanation of these discrepancies, but further reflection makes it evident. One of the most important elements in determining the depth of the pipe is the degree of " top-lag," that is, the degree to which the solidification of the top of the ingot lags behind that of the bottom. 'Through this lagging the steel of the upper part of the ingot is able to run down and fill the pipe below as fast as it forms. To the importance of this lagging I called attention in my original paper.' Sand vs. Iron Molds.-If we compare two like ingots, one cast in an iron and the other in a sand mold, we see that the top-lag' is much greater in the former than in the latter, be¬cause in the former the lower part of the ingot is cooling off fast while the metal is running into the upper part. It is perhaps easier to look at this as a case of the solidification of the hot-

Dec 1, 1909

By Jean Howard

ThE formation of the (100) [001) texture in 3-1/4 pct Si-Fe strip was first reported by Assmus ef a1.l in 1957. Since then much experimental work has been carried out with a view to establishing the mechanism involved. The papers cited above state that the (100) [001] texture was developed in strip rolled from material melted and cast in vacuum. (The impurity content of the ingot is reported as 0.005 pct.) The present note records that similar results can be obtained in material processed by powder metallurgy. A processing schedule is described.which enables the texture to be formed in strip up to 0.010 in. thick, but there seems no reason why this should not be achieved in thicker strip, provided that large grains are developed after sintering. The materials were prepared from Carbonyl Iron Powder Grade MCP (particle size 5 to 30 p) of the International Nickel Co. (Mond) Ltd. The powder contains about 0.15 pct 0, 0.01 pct C, 0.004 pct N, <0.002 pct S, $0.005 pct Mg and Si, and 0.4 pct Ni— that is, it is substantially free from metallic impurities other than nickel, which is thought to be unimportant in the present work. The silicon powder was 99.9 pct purity, or material of transistor quality (ground in pestle and mortar). The mixed powders (3-1/4 pct Si to 96-3/4 pct Fe) are heated in hydrogen at 350" and 650°C to deoxidize the iron before sintering loose at temperatures between 1350" and 1460°C (depending upon the ultimate thickness of strip required) for up to 24 hr. The object of the high-temperature sinter is to develop a large grain size at this stage. Alternatively, the loose sintering can be done at a lower temperature followed by rolling or pressing and then annealing at temperatures between 1350" and 1460°C. Both methods produce large grains, which remain large throughout the process. The compact is then hot-rolled to approximately 1/8 in. with high-temperature interstage anneals if necessary. This step is taken to avoid intercrystalline cracking which would occur if the material of such large grain size were cold-worked. The bar is then annealed at 1050°C and reduced to its final thickness by approximately 50-pct reductions and 1050°C interstage anneals. Throughout the process the dew point of the hydrogen furnace atmosphere is maintained at about -40°C. Samples were annealed in hydrogen at various temperatures and times. Secondary recrystalliza-tion to (100) [001] was developed on the thinner material (i.e., up to 0.002 in.) by annealing in hydrogen at 1050" to 1200°C with a dew point of - 40°C or in vacuum (10-5 Torr) at 1050°C. With the thicker materials (i.e., up to 0.010 in.) the best results were obtained by annealing in hydrogen at 1200°C with a dew point of - 55°C. Complete secondary recrystal-lization to (100) [001] textures was obtained. Above these temperatures secondary recrystallization to (110) [001] tended to develop. The final annealing of samples was normally carried out with the samples placed between recrystal-lized alumina plates, but some experiments were performed with the samples suspended so that their surfaces were not in contact with anything except hydrogen, and these were equally successful in developing secondary crystals. An approximate determination of the proportion of material (before secondary recrystallization took place) having crystals with the (100) or (110) planes in or near the rolling plane showed that 11 pct of the sample had (100) and 16 pct (110). The method used for the determination is described below. A sample was annealed at a temperature just below the secondary recrystallization temperature and etched to reveal the (100) planes. The approximate area covered by crystals having (100) or (110) in or very near the surface was measured on the screen of a Vickers projection microscope. This was repeated for twenty positions chosen at random and a mean of the results calculated. The main hindrance to developing the secondary crystals in the thicker materials was the difficulty of obtaining a large enough initial primary grain size before secondary recrystallization. This was overcome by increasing the particle size of the silicon powder used. During the course of the work, it had been observed that the larger the grain size after sintering the more likely it was that the material would be successful in developing secondary crystals at a later stage. An experiment was therefore carried out to determine whether the material with the larger grain was more successful in developing secondary crystals due to the large grain produced at the sintering state per se or whether it was due to the greater reduction of silica brought about when the sintering temperature was raised in order to increase the grain size. A comparison was made between two compacts, one of which was made with silicon powder of 60 to 100 mesh, the other with silicon powder which was finer than 200 mesh. F?r this experiment, use was made of a phenomenon previously observed that the larger the particle size of the silicon powder employed in making a compact, the larger is the grain size of the compact. The silicon powder was ground

Jan 1, 1964

By R. P. Heuer, Paul M. Tyler

THE literature on refractories, although fairly extensive, is so scattered through books and periodicals as to be difficult of access to the general reader and most of the individual papers serve merely to illuminate some particular phase of the industry. Two general treatises by American authors8.16 are available, also the somewhat older works by a well-known British authority, 12,13 but these make their appeal to the technically minded ceramic engineer. Another small group of publications deals with the use of refractories, mainly in the iron and steel industry.1, 3,5,6,11,15 Raw materials utilized by the refractories industry have been covered by sundry books and articles. For the relatively nontechnical reader and economist, however, there appears to be no single review that purports to describe the industry as a whole. Furnace linings and other products that are classed as "refractories" are designed primarily to withstand high temperatures but this important property is by no means the only requirement; a suitable refractory material must likewise withstand slagging (chemical&apos; action), abrasion (physical wear), and spalling, as well as the various other stresses and physical phenomena induced by heat, of which softening or incipient melting is only one phase. Nevertheless, subject to these highly practical considerations, the definition of a refractory material is based upon temperature resistance. Broadly speaking, any material that shows obvious signs of fusion after being heated slowly to 1500°C (2732°F) cannot be classified as a refractory material. The characteristic properties and requirements of refractory materials are conveniently summarized in Fig 1, prepared on the American Refractories Institute Fellowship at Mellon Institute, Pittsburgh, Pennsylvania. Most of the factors of service and properties of refractories given in this chart are interdependent and are greatly affected in degree by the functions of temperature and time. The factors in the chart are believed to cover the commoner questions.

Jan 1, 1949

By H. L. Eiselstein, F. P. Huston, B. B. Betty

An extensive program for the establishment of creep data on high-nickel alloys has been in progress during the past seven years. This paper presents the accumulated data on two solid solution alloys, cold-drawn, annealed Monel and cold-drawn, annealed Inconel. Data on these two alloys in other conditions will be published at a later date. Monel, a nickel-copper alloy, is normally considered a corrosion-resistant material, but it will be shown that it also has considerable creep strength, validating its use at temperatures up to and including 900°F. Inconel, a nickel-chromium-iron alloy, is definitely a heat-resisting alloy possessing good creep strength and oxidation resistance up to iiooOF., and because of its oxidization resistance has been used successfully at much higher temperatures for lightly stressed parts. The literature contains but meager data on the creep properties of high-nickel alloys. Howevcr, Bennett and McAdam have presented a substantial quantity of creep data for cold-drawn Monel.1 The material as tested was not representative of mill production for it was cold-drawn to a reduction of area of 40 per cent as against 13 per cent, which is the mill standard for Monel. Twenty-two individual tests were run on each alloy in the investigation described in the following pages. The data and curves presented herein represent an integration of all the tests to obtain the most accurate picture of the creep properties of these alloys. Neither of the two alloys was found to be embrittled by the combination of temperature and stress, as evaluated by room-temperature tensile and impact tests that were made following creep testing. These data indicate that no tendency toward embrittlement exists. It is recommended that 6300 lb. per sq. in. be used as a working stress for cold-drawn, annealed Monel at 900°F. and 13,200 lb. per sq. in. for cold-drawn, annealed Inconel at the same temperature. Table 8 lists recommended working stresses, based on 80 per cent of the stress to produce a minimum creep rate of 0.01 per cent per 1000 hr., for Monel and some steels. Equipment The equipment used for these tests consists of Colville creep-testing machines manufactured by the Tinius Olsen Testing Machine Co. The load is adjusted, depending on the stress level, to give an error in the stress of not more than ± 0.1 per cent. This is based on considerations of lever sensitivity and the stress used for the standard (A.S.T.M. Tentative Standard E22-38T) 0.505-in. diameter creep specimen having a 2-in. gauge length. The single-specimen furnaces are provided with primary and secondary windings, from

Jan 1, 1945

By Ferris E. Sainsbury

As most mining companies utilize contractors rather than in-house drilling departments, it is difficult for most mining engineers to become familiar with drilling techniques This chapter will explain the various drilling options available to the mining industry through the services of a drilling contractor. It will also suggest improvements in program planning and specification writing by the mining company representatives to enable them to derive maximum benefit from the contractor.

Jan 1, 1979