Search Documents

By W. M. Parris, P. D. Frost, H. A. Robinson

The effects of hydrogen content and strain rate on the static tensile and notch-rupture properties of the Ti-3Mn-complex alloy heat-treated to differed strength levels were investigated. The extent of embriulement was found to be proportional to the amount of hydrogen present and the strength to which the specimens were heat-treated. The research suggests the possible necessity of specifying lower hydrogen limits than are now allowed when titanium alloys are heat-treated to higher strengths than are presently used. The research also supports a hypothesis advanced earlier for a mechanism of hydrogen embrittlement. MUCH attention has been focused on the effects of hydrogen in in Most of the published in- formation has dealt with the effects of hydrogen on alloys in the annealed or lowest-strength condition. The work of Kotfila and Erbin3 is one of the few exceptions. In view of the fact that heat-treatments are now being used to produce high strength in titanium alloys,' it is necessary that more attention be given to the effects of hydrogen on these alloys in the heat-treated condition. Research was initiated to establish the effects of hydrogen on the properties of the Ti-3Mn-complex alloy at various strength levels. This research, which supplemented that of Kotfila and Erbin, was started because it was found that high-strength tensile specimens of this alloy were strain-rate sensitive. The essential results of the research are summarized in this paper. MATERIALS AND EXPERIMENTAL PROCEDURES Material for this investigation was a 41/2-in.-diam bar forged from a single commercial heat of the Ti-3Mn-complex alloy having the composition given in Table I. The as-received forging was reduced further by forging at 1750°F to 3/4-in. square bars. About one fourth of this material was vacuum annealed at 1400°F for 24 hr to obtain a base hydrogen content of 25 ppm. The remaining bars were hydrogenated to levels of 90, 140, and 260 ppm in a large Sievert's apparatus in the following manner: Four 3/4-in. square bars, 5 in. long, were placed in the reaction chambzr. The chamber was evacuated, heated to 1400°F, and a measured amount of hydrogen was introduced. When absorbtion was complete, as indicated by the drop in pressure, the reaction tube was cooled and the bars removed. Each batch of bars was then sealed in individual evacuated Vycor containers and heated for 24 hr at 1400°F in order to distribute the hydrogen homogeneously. After vacuum-annealing or hydroge nation, the bars were rolled at a temperature (1400°F) below the ß-transus to 1/2 - in. - diam rounds. Groups of the rolled specimens representing each of the hydrogen levels were given the following heat-treatments: 1) One hr at 1300°F, water-quenched. 2) One hr at 1300°F, water-quenched, and aged 8 hr at 1100°F. 3) One hr at 1300°F, water-quenched, and aged 4 hr at 1000°F. 4) One hr at 1300°F, water-quenched, and aged 48hr at 800°F. Heat-treated bars were machined into standard 0.250-in.-diam tensile specimens having 1-in. gage lengths. Throughout the processing and testing of this material, hydrogen analyses were made by vacuum-fusion methods to check for accuracy of hydrogen additions, homogeneity, and possible losses during processing. A summary of these analyses is given in Table II It may be seen that the actual hydrogen contents were reasonably close to the desired levels. In addition, it was noted that the variation in hydrogen content within any one bar did not exceed

Jan 1, 1959

By L. A. Roe, E. A. Elevatorski

Wollastonite, named after William H. Wollaston, an English chemist, is a calcium metasilicate, CaSiO3; CaO: 48.30%, SiO2: 51.70%. It has a short history as an industrial mineral. The earliest production of wollastonite is reported to be from a deposit near Code Siding, located north of Randsburg, CA. At this locality small tonnages of wollastonite were quarried during 1933-34 and 1938-41, and processed into mineral wool. This operation was largely experimental and virtually no United States production was again reported until the 1950s when a large deposit near Willsboro, NY, was developed by the Cabot Corp. A processing plant was placed onstream in 1953, with nearly continuous production to date. It is currently operated by NYCO, a division of Processed Minerals, Inc. Since 1958, wollastonite deposits in the Little and Big Maria Mountains of Riverside County, and in the Panamint Range of Inyo County, both in California, have operated intermittently for production of both ornamental and commercial wollastonite. During 1980, the United States was the major producing country, furnishing about 75% of the world's output. Current production comes from Finland, Mexico, India, and Kenya. Small amounts have been shipped intermittently from the USSR, New Zealand, Republic of the Sudan, Republic of South Africa, and Namibia (South-West Africa). The principal use of wollastonite is in the manufacture of plastics. Other uses are for paints, ceramics, adhesives, fluxes, glazes, thermal insulation board, and refractory products. Mineralogy Pure wollastonite, CaSiO3, has the composition of 48.3% CaO and 51.7% SiO2. However, it is seldom found in the pure state due to the ease with which it takes into solution the metasilicates of manganese, magnesium, iron, and strontium. Predominantly, wollastonite occurs as a contact metamorphic deposit forming between limestones and igneous rocks. Commonly associated minerals are garnet, diopside, epidote, calcite, and quartz. It has a specific gravity of 2.8 to 3.0, and hardness of 4.5 to 5 on Mohs' scale. When pure, it has a brilliant white color, but with impurities it may be grayish or brownish. Luster is vitreous to pearly. Melting point of wollastonite is about 1540ºC. Wollastonite occurs in coarse-bladed masses, rarely showing good crystal form. It is usually acicular or fibrous, even in the smallest of particles. The most unique property of crushed and ground wollastonite is its cleavage. Fragments of crushed wollastonite tend to be needle-shaped, imparting a high strength, and this property is the basis for many of its uses. The fiber lengths are commonly in the ratio of 7 or 8 to 1, length to diameter. The average diameter of wollastonite is 3.5 µm. Some crystals of wollastonite fluoresce under short-wave or longwave ultraviolet light, or both, with colors ranging from yellow-orange to pink-orange. Specimens may also show phosphorescence. The acicularity of wollastonite is a property of considerable importance to the marketplace. The plastics industry makes utilization of high aspect ratio grades of wollastonite (20:1) for reinforcing thermoplastics and thermoset polymer compounds. The naturally high pH of 9.9 (10% water slurry) is a prime property to the coatings industry. The coatings industry uses milled grades of wollastonite as a pH stabilizer in interior and exterior PVA and acrylic latex systems. Processed wollastonite can have a G.E. brightness of 90 to 93. Chemically, wollastonite is inert and this property makes it useful as a filler and reinforcing agent. There are two polymorphs of calcium silicates: wollastonite, a low temperature form, and pseudowollastonite, a high temperature

Jan 1, 1983

By Howard I. Young

WHEN so many statements are being made relative to the requirements of zinc metal, it is difficult for some of us who are acquainted with the industry to visualize how it is possible to step up production so as to supply some of the fantastic requirement figures that are published from time to time. I shall attempt to approach this subject from the standpoint of existing conditions which affect production, also keeping in mind the price ceiling under which the industry operates. Total production of primary and secondary zinc in the United States for 1941 will be about 878,000 tons, to which should be added about 36,000 tons of Mexican slab zinc available for consumption or export from the United States, giving a total available of 914,000 tons. Production of slab zinc of all grades in 1942 should be 953,000 tons. Adding the available Mexican supply should bring the total to 989,000 tons.

Jan 1, 1942

By E. S. Bumps, H. D. Kessler, M. Hansen

The titanium-rich end of the Ti-AI phase diagram has been determined to the compound TiAI3 (62.7 pct Al), thus joining the aluminum-rich portion previously investigated by others and completing the diagram. Micrographic analysis and X-ray diffraction were the chief methods used to determine the phase relationships. THE Ti-Al phase diagram has been investigated as part of a program on titanium phase diagrams for the Wright Air Development Center. Included in the available information concerning the phase relationships in titanium-rich Ti-A1 alloys is a brief statement by Brown' that: "aluminum raises the transformation temperature to 1000°C (183Z°F)." This observation is interesting in that it is the first example of a metallic alloying component raising the transformation temperature of titanium, and consequently widening the field of the a solid solution. Busch and Freyer' presented resistivity data which indicated the formation of titanium-rich solid solutions of 1 and 3 pct A1 alloys prepared by powder metallurgy methods. Duweza found that there is only one other intermediate phase other than the known compound TiA1, (62.7 pct Al). This phase, designated as y, is of variable composition; its crystal structure is of the AuCu type and is therefore based on the composition TiAl (36.02 pct Al). Earlier work on the constitution of the aluminum-rich alloys has been reviewed by Hansen, and need not be discussed here. The tetragonal crystal lattice of TiAl,, as found by Fink, Van Horn, and Budge," was confirmed by Brauer." Recently, Schubert7 has reported that TiA1, is homogeneous within a limited composition range; however, the solubility limits were not given. The Ti-A1 phase diagram as presented in. this paper was determined by micrographic analysis of alloys containing from 1 to 62 pct Al, annealed at and quenched from temperatures between 700" and 1400°C. The phases and phase ranges investigated extend to the compound TiA1, (62.7 pct Al) to join the aluminum-rich end of the system determined by other investigators, thus completing the diagram. Methods of Investigation Preparation of Alloys: Iodide titanium, 99.9+ pct pure, obtained from the New Jersey Zinc Co., and high-purity (99.99+ pct) aluminum sheet from the Aluminum Co. of America were used to make up alloy ingots weighing 10 to 20 g. Detailed descriptions of melting techniques have been presented previously for work on the Ti-Mo and Ti-Cb> nd Ti-Si" phase diagrams. Briefly, the melting practice consisted of arc melting an accurately weighed charge in a copper block crucible insert in a non-consumable tungsten electrode furnace, under helium at atmospheric pressure. All ingots were carefully weighed after melting to detect possible losses. Comparison of weight before and after melting showed no appreciable weight changes. Also, chemical analyses were in close agreement with nominal compositions, Table I. The diagram as presented is, therefore, based on nominal compositions. Alloys were prepared having the following nominal aluminum contents: 1 ... 36 (1 pct increments), 38, 40, 41, 42.5, 44, 45, 46, 47.5, 49 . . . 64 (1 pct increments), 67, 70, 80, and 90. Ingots with up to 14 pct A1 were cold-pressed various amounts in order to increase the rate of attaining equilibrium structures on heat treatment. The amount of cold deformation that could be applied decreased with increasing aluminum content, until alloys containing 12 pct A1 or more cracked after only a few percent deformation. Annealing Treatments: Samples annealed at temperatures of 700" to 1000°C were sealed in

Jan 1, 1953

By R. I. Jaffee, C. M. Craighead, G. A. Lenning

THERE has been considerable discussion among A metallurgists and others interested in the development of titanium alloys as to the nature of the fine line markings which appear in the microstruc-tures of unalloyed titanium and a titanium alloys. These markings have been variously called x phase, etching pits, and twins. Figs. 1 to 3 show typical examples of the line markings as they appear, respectively, in high purity iodide titanium, commercial purity titanium rod, and a high purity a alloy containing 0.2 pct N. The commercial purity titanium sample, shown in Fig. 2, contains both line markings and some spheroidal retained-ß phase. The ß phase seen in this micrograph should not be confused with the line marking, since it originates from the iron present as an impurity in the sponge metal. It will be noted that the line markings seem to have a definite orientation pattern with respect to the grains and in titanium noticeably resemble the precipitation occurring in artificially aged high purity Al-Cu alloys. This similarity led to the hypothesis that the line markings observed in titanium and a titanium alloys resulted from precipitation of some unknown phase. With the work of Hägg1 and McQuillan2 as background, there was little reason to suspect hydrogen of being responsible for the line markings. Hagg reported that up to 33 atomic pct H was soluble in a titanium, and McQuillan reported an a solubility of up to 8 atomic pct. Furthermore, McQuillan examined metallographically a 5.1 atomic pct H alloy quenched from 300°C and stated that the structure appeared to be a single-phase a solid solution. Line markings have been observed frequently and were first noted by Jaffee and Campbell3 in 1949. They did not observe them in vacuum-annealed titanium and a Ti-O and Ti-N alloys, but did observe them in Ti-H alloys containing 0.25, 0.5, and 1 atomic pct H. They stated that it was doubtful that the markings were a second phase based on hydrogen, because 1 atomic pct was far from the accepted solid solubility of hydrogen in titanium. Finlay, Resketo, and Vordahl,4 in 1950, concluded that the markings were a true second phase as a result of observations on their etching characteristics. Anderson5 Commenting on these markings in titanium was inclined to associate them with hydrogen, but was loath to call them titanium hydride, because of the reported high solubility of hydrogen. Work at Battelle Memorial Institute for the Navy Bureau of Aeronautics," done concurrently with the work described in this paper, provided information on the experiment converse to that described by Jaffee and Campbell in 1949. This work showed that the amount of line markings in unalloyed titanium could be decreased by vacuum annealing at elevated temperature. It was suggested that this was the result of removal of hydrogen; previously, the data of Jaffee and Campbell9 howed that the markings appeared when hydrogen was added. Recent work at Battelle for the Ordnance Corps, Department of the Army, which is described here, now establishes the identity of the markings as a titanium hydride phase. A sample of high-purity titanium rod 1/4 in. diam, 0.009±0.001 wt pct H (0.43 atomic pct), Fig. 1, was resistance heated in a 0.05 micron vacuum for 41/2 hr at 1500°C. During the early states of heating, the pressure increased to 150 microns, indicating that gases were being evolved. After cooling in vacuum, the iodide titanium rod was analyzed for hydrogen. Vacuum-fusion analysis showed 0.0006 ±0.0003 wt pct H (0.03 atomic pct) to be present.* Metallographic examination of the vacuum-annealed rod showed only a transformed ß structure. There was no evidence of fine line markings, Fig. 4. A section of this vacuum-annealed rod was cold rolled to 0.040 in. thick sheet and annealed for 1 hr

Jan 1, 1953

FRIENDS of the late Charles F. Rand presented in 1930 a sum of money from which the income is available to support various phases of the work of the Institute in which Mr. Rand was so deeply interested. At present the fund amounts to $10,400. The specific terms of the deed of gift are as follows: "The fund collected to establish a memorial to the late Charles F. Rand shall be placed in the custody of the Board of Directors of the American Institute of Mining and Metallurgical Engineers, to be set up as a trust to be known as the `Charles F. Rand Foundation,' the income of which shall each year be applied to a distinct purpose to be decided upon in that year by vote of the Board of Directors. This purpose shall be such as to promote the general welfare of the Institute and to constitute a permanent memorial of the usefulness of Mr. Rand, who for many years gave unstintingly of his time and talents in its service. "It shall be within the discretion of the Board of Directors to establish a medal to be known as the Charles F. Rand Memorial Medal to be awarded at such a time and under such rules as may be determined by the Board of Directors, for Distinguished Achievement in Mining Administration." The establishment of this medal was announced at the annual meeting in February, 1932, the term "mining" being defined in its broad sense to include metallurgy and petroleum. Robert Linton is chairman of the Charles F. Rand Foundation Award Committee.

Jan 1, 1944

By Albert Sauveur

IN an important paper on The Critical Ranges of Pure Iron1 presented at the May, 1913, meeting of the Iron and Steel Institute, Professor Carpenter reports and illustrates the results obtained by him in determining the critical points of some very pure electrolytic iron sheet about 0.01 in. thick. The iron strip was rolled into the form of a cylinder 1; in. long and fn in. wide, weighing 42 g., the thermo-couple being inserted in a small hole in the center. The points Ac3 and Ar3 were readily detected, as well as the point Art, but the point Act was absent from every heating curve. The author concluded from this occurrence that the conception of A2 as an independent allotropic change must be abandoned. At the October, 1913, meeting of the American Institute of Mining Engineers, Dr. G. K. Burgess and J. J. Crowe read a paper on The Critical Ranges A2 and A3 of Pure Iron2 in which they described some extremely important experiments conducted by them at the Bureau of Standards, Washington, D. C. They tested Professor Carpenter's electrolytic iron and detected a sharp and well-defined absorption of heat corresponding to the point Act. Professor Carpenter's failure to detect this point is explained by them on the ground that unless the iron be in a single piece entirely surrounding and in contact with the thermo-couple junction, the thermo-couple will integrate the irregular progress of the heat through the sample and the curves will lose their sharpness. In discussing Messrs. Burgess and Crowe's paper, Professor Carpenter accepted this explanation as probably accounting for the absence of Act in his heating curves.

Jan 2, 1914

By T. L. Joseph

S. T. Killian (Johnstown, Pa.)—This is one of the finest papers I have read. Tying in stoichiometric calculations with furnace performance and practice is a step which had to be taken sooner or later. The noteworthy difference between Dr. Joseph's type of calculations and regular blast furnace calculations is that the Ib mol system is used as a basis. With the Ib mol system, weights, volumes, and chemical reactions can all be expressed in the same equation. In the paper, wind, ore, flux, and fuel are all expressed as lb or lb mols. Probably Dr. Joseph does not realize it, but the vague word coke appears only twice in the entire paper. Lb of C and Ib mols of C are followed through reactions but the word coke appears only as 1560 lb coke per ton of pig and 1700 lb of coke per ton of iron. Obviously in order to understand furnace reactions, the coke should be expressed as lb or lb mols of C. Furnaces can also be compared more easily. In some respects the paper is too thorough and too complete. The effects of the metalloids reduced into the iron upon the top gases represents a difference of less than 3 pct of the CO formed in the bosh. Due to the completeness of the calculations in relation to the CO/CO2 ratio, this was included and was necessary. However, the exclusion might have enabled more furnace men to follow the lb mol system of calculations through the blast furnace to a better degree. By considering only irons of similar analysis, this part of the calculations might have been omitted. However, if this had been done, total rewriting of the paper later would have been necessary in order to make the work complete as it is now. It also would not have been nearly as authoritative. In the paper, there appears the reaction: H2O + CO ? CO2 + H2 [I] Dr. Joseph states that he did not take this reaction into consideration in any calculations pertaining directly to the paper. The piobable reason- for this is that although it contains all the main reacting top gases except N2, it is rather inflexible since it is monomolecular in relation to each of the reacting gases and does not tie in with the gasification of C. Actually the reactions: H2O + C ? CO + H2 [2] 2H2O + C ? CO2 + H2 [31 and the solution loss reaction: CO2 + c ? 2c0 [41 tend to assume an equilibrium through the reaction: H2O + CO ? CO2 + H2 [I] which should be considered a balancing or equilibrium reaction. Reactions 2, 3 and 4 permit furnace conditions to balance with the CO/CO2 ratio and H2 formation. They tie in with the solution loss. Reaction 1 unites them chemically. Probably the best calculation to make at this time would be to try to find the relative importance of the CO2 from the flux and the H2 in the dilution on an actual furnace gas analysis. For this purpose the Dob-scha-Carnegie-Illinois paper—"Effect of Sized and Sintered Mesabi Iron Ores On Blast Furnace Performance" is chosen. This paper was presented before the blast furnace section of the AIME in 1948. This represents the best large scale furnace operation available to me. Unfortunately the changes were brought about by beneficiation of the burden and not by changes on one burden. In choosing the basis for the calculation in relation to the furnace, 100 mols of dry top sgas is chosen. This leaves something to be desired inasmuch as the nitrogen basis is changing but I believe it will be better understood than any other type and it is the easiest to use.

Jan 1, 1952

By Clyde E. Williams, JAMES L. GREGG

THIS review of the past year's progress in iron and steel metallurgy presents examples of only a few of the interesting or important accomplishments made in the United States. In the field of iron ore concentration increased attention was given to the study of the more difficultly separated wash ores and some progress was made in tabling. One difficulty with the table, in concentrating iron ore where the percentage of concentrate in the feed is large, has been the removal of fine silica from the thick layer .of concentrates in the cleaning zone. One company has -Made an important contribution toward the solution of this problem by an extension of the well-known plateau principle. By a special riffling of the plateau section of the table, the concentrates are crowded together. This action forces the fine silica to the top of the bed in the cleaning zone, whence the cross-flowing currents of water -can wash it into the middling product. Some work has been done on the application of froth flotation to the concentration of iron ores. Laboratory experiments were made at the Colorado School of Mines in which hematite was, successfully floated. Using oleic acid as a frothing and collecting agent and sodium carbonate as the conditioning agent, a high recovery of rich ,concentrate was obtained. A laboratory flotation unit is in use at Taconite, on the Mesabi range, and a commer-

Jan 1, 1932

By W. W. Duecker

SULPHUR is a peculiar combination of a nuisance and a useful element. Most of the nonferrous metallic ores contain large amounts of it in the form of sulphides, which the metallurgist has wasted up the chimney, since the sulphur dioxide formed is generally too dilute to make recovery economical and practical. Iron ore does not contain much of the unwanted sulphur; in pig iron and coke it is most unwelcome. Gold metallurgists can get along nicely without sulphides in their cyanide plants and yet they find matte-a sulphur compound -an excellent collector for gold and silver in base-metal smelting. Also, sulphur appears in the non-metallics as in barite, gypsum, Glauber's salt, and celestite, all to useful purpose.

Jan 1, 1938

By John H. Hollomon

The interpretation of notched-bar impact results has been a matter of controversy since the introduction of more or less standard tests by Fremont,' Charpy2 and others at the turn of the century. Many investigators3-l1 have contributed to the understanding of the significance of such tests. Several symposiums12,13 have been held with the express purpose of discussing the significance and interpretation of the impact tests. It is not the purpose of this paper to review all these contributions to the development of the knowledge on this subject, but rather to present an interpretation of notched-bar impact tests that appears to be in agreement with the available published data. Fundamentally, the interpretation discussed in this paper of the brittle failure of some steels in notched-bar impact test is similar to the qualitative analysis presented by Ludwik3 in the I92o's. Essentially, Ludwik stated that the function of the notch was to increase the tensile stress necessary for yielding, and that brittle failure occurred when the stress necessary for yielding exceeded the normal stress required for fracture (with no plastic deformation). Ludwik, however, had no means of measuring this normal stress necessary for failure of a plastically* undeformed metal, therefore he could not extend his interpretation beyond the qualitative stage. Kuntze14 and recently Mc-Adam15 attempted to determine the effect of deformation on the stress necessary for fracture by testing, in tension, specimens notched to various depths and angles. Because of the uncertainties in Kuntze's (and McAdam's) analysis of the stresses (which have been pointed out by Sachs16) and the inherent nonuniformity in the stress distribution in notched bars, the results of such investigations are difficult to interpret. A more direct method of measuring the effect of deformation on the fracture stress was suggested in previous papers"-18 and has been utilized in the present investigation. The present paper concerns itself primarily with the behavior of notched impact specimens. The effects of strain rate, temperature, and stress distribution, which are discussed with reference to the impact specimen, apply just as well to the behavior of metal at the bases of notches in any engineering structure. All that is necessary is to determine the stress distribution in the structure at the base of the notches.

Jan 1, 1944

By John H. Hollomon

The interpretation of notched-bar impact results has been a matter of controversy since the introduction of more or less standard tests by Fremont,' Charpy2 and others at the turn of the century. Many investigators3-l1 have contributed to the understanding of the significance of such tests. Several symposiums12,13 have been held with the express purpose of discussing the significance and interpretation of the impact tests. It is not the purpose of this paper to review all these contributions to the development of the knowledge on this subject, but rather to present an interpretation of notched-bar impact tests that appears to be in agreement with the available published data. Fundamentally, the interpretation discussed in this paper of the brittle failure of some steels in notched-bar impact test is similar to the qualitative analysis presented by Ludwik3 in the I92o's. Essentially, Ludwik stated that the function of the notch was to increase the tensile stress necessary for yielding, and that brittle failure occurred when the stress necessary for yielding exceeded the normal stress required for fracture (with no plastic deformation). Ludwik, however, had no means of measuring this normal stress necessary for failure of a plastically* undeformed metal, therefore he could not extend his interpretation beyond the qualitative stage. Kuntze14 and recently Mc-Adam15 attempted to determine the effect of deformation on the stress necessary for fracture by testing, in tension, specimens notched to various depths and angles. Because of the uncertainties in Kuntze's (and McAdam's) analysis of the stresses (which have been pointed out by Sachs16) and the inherent nonuniformity in the stress distribution in notched bars, the results of such investigations are difficult to interpret. A more direct method of measuring the effect of deformation on the fracture stress was suggested in previous papers"-18 and has been utilized in the present investigation. The present paper concerns itself primarily with the behavior of notched impact specimens. The effects of strain rate, temperature, and stress distribution, which are discussed with reference to the impact specimen, apply just as well to the behavior of metal at the bases of notches in any engineering structure. All that is necessary is to determine the stress distribution in the structure at the base of the notches.

Jan 1, 1944

By Emil Gathmann

STEEL as it is poured, or teemed, into the mold for forming the ingot may be broadly separated into two divisions; i.e., effervescing or gassy steel, also termed evolution steel, and non-effervescing or killed steel, also termed solution steel. Between these primary divisions there are various types having the characteristics of both divisions but really not belonging to either; such steels are termed semi-piping, rising, or wild, as the type may be. True unkilled, or effervescing, steel should contain large volumes of gases, which are evolved while the metal is being teemed, or cast from the ladle nozzle into the mold, and while the temperature of the steel is being reduced prior to the solidification or freezing of the steel, the upper portion, or top, of the ingot remaining liquid due to the evolution of gases until an ingot skin of considerable thickness has been formed. These gases consist principally of hydrogen, carbon monoxide, nitrogen, and ammonia. It is generally understood that nitrogen gases are the first evolved and form the skin blowholes, at times troublesome, in the forming solidifying ingot. Ingots made of effervescing steel will always contain a large number of blowholes. Such blowholes are not deemed objectionable in various products if they occur well within the interior of the ingot where they will not be subject to oxidation upon the ingot's cooling and subsequent re-heating and rolling or forging. Very little top or bottom discard is taken from this type of ingot as pipes, or large shrinkage cavities, at the upper portion of the ingot do not usually occur, the difference in volume between the liquid and the solid steel (6 to 10 per cent.) being compensated for by the innumerable blowholes distributed throughout the body of the , ingot. Of the 40,000,000 tons of steel made in the United States during the year 1919, at least 35,000,000 tons of ingots were made of gassy or semi-gassy steel. Killed, or solution, steel is termed true piping steel from the characteristic pipe or shrinkage cavity that usually occurs in the uppermost central portion of the ingot.

Jan 8, 1920

By Frederick Vickery

THE discovery of oil on the Goleta anticline has extended the petroliferous areas of California 18 miles west of the previous limit at Summerland and 35 miles south of the fields at Santa Maria. In each of these localities the oil is found in the Miocene-Pliocene strata, but as the oil at Goleta is found in the Sespe formation, which is generally considered as Oligocene or lowermost Miocene, the Goleta field extends the production of that horizon 52 miles west of South Mountain, the previous western outpost. Two horizons of high-gravity, paraffin-base oil have been found at shallow depths, and the exploratory well, Goleta No. 1, is now being drilled to test the productivity of an expected horizon in the Meganos formation. The Goleta structure is 12 miles west of the city of Santa Barbara and 2 miles north of the coast. Although it is within part of the old Spanish Rancho, Los Pueblos, it corresponds to T. 4 N., R. 29 W., S. B. B. and M., Santa Barbara county, California. The discovery well, Goleta No. 1 was drilled by the Miley Petroleum Ex-ploration Co. on the Tecolote ranch in the part of the Spanish grant corresponding to the sw. 1/4 of the nw. 1/4 of Section 3. Despite the apparent isolated position of the Goleta field, it is within the Ventura basin. The idea that the Ventura basin terminates at the ocean beach near the city of Ventura is neither sup-ported by the geologic structures nor the sequence of strata west of that city. This basin at the present time is known on the land as the Santa Clara valley and beneath the sea as the Santa Barbara channel. It extends westward to Point Concepcion. The Ventura basin, before the Miocene and Pliocene epochs of deformation, was much broader than at the present time. It is bounded by two lines of uplift, the Santa Ynez range on the north and the Santa Monica mountains with their extension, the Channel islands, on the south. Both of these ranges trend east and west. The Ventura basin and the mountains that bound it are part of a remark-able east-west orogenic unit, which interrupts the pre-vailingly northwest ranges along the Pacific Coast.

Jan 10, 1927

By R. J. Grissom

PHOSPHATE deposits have been worked in many countries of central and south central Tennessee, but only ht ebrown rock deposits of Maury and Giles Counties will be discussed at any length in this articles, as all of the major opeations are now located there. They are: Mt. Pleasant District-Federal Chemical Co., Hoover and Mason Phosphae Co., International Minerals and Chemical Corp. (Maury and Giles Counties), Virginia-Carolina Chemical Corp. (formerly Charleston Mining Co.), and Victor Chemical Co. Columbia District-Armour Fertilizer Works and Monsanto Chemical Co. In the near future, the well-known, extensive deposits of blue rock in Lewis and Hickman Counties,also the brown rock in Hickman, Willamson, Summer and Davidson Counties, will again come into production. Certain physical peculiarities of the Tenessee deposit have played an important part in the design and use of mining and milling equipment.

Jan 1, 1944

By Willard C. Lacy

Rather than attempting to present a summary of the many and highly varied papers that have been presented at this symposium on sampling and grade control, I will attempt to extract the general philosophy of analysis and approach, and attempt to identify the trend of future developments. First, the term "sampling" is used with its broadest connotations. A sample consists of a representative portion of a larger mass, and must represent the mass not only in the grade of contained metals or minerals, but also in all other respects in terms of mineralogy and mineral quality (1, 5), deleterious materials, recoverability of economic components, physical behavior, geophysical response (I), and even archaeological and environmental aspects (7, 11). The sample must be taken from a locality and in such a manner and quantity that it is representative of the larger rock mass. This calls for complete and accurate geological control and an understanding of the nature and distribution of the contained chemical and physical elements and a record of the effectiveness of the different sampling methods. Second, value of a given mass of ore material is based upon its profitability - the difference between recoverable value and costs to achieve recovery, beneficiation and sale. There is a strong movement in mining geology control toward more complete analysis in determining cutoff grades and in grade control, as illustrated by the kriging of metallurgical recovery factors as well as grade at the Mercur Mine (8). To achieve a "profit- ability factor" as a guide for economic mining practice requires further integration of: 1) the value of contained metal or mineral, 2) percentage recovery of values, 3) dilution of ore with waste rock, 4) addition to, or loss of value as a consequence of by-product materials or deleterious components, 5) cost of producing a saleable product plus mini- mum profit to justify the effort (cutoff), and 6) cost of land restoration (7, 11). All these parameters vary with the rock type, rock structure, mineralogy, depth, geometry, mining and metallurgical methods, but they must be sampled and analyzed if sampling and grade control are to reflect profitability. A wide variety of deposits has been presented at this symposium; each deposit with its own problems and special solutions. Deposits containing high unit-value components, e.g. precious metals and diamonds, present special problems in the obtaining of accurate samples and generally require statistical analysis control methods or may disregard or modify occasional high or occasional low values, based upon experience (12 ) Grade control may be accurate for the long term but may vary for the short term. Bulk sampling is always essential. Deposits containing metals or minerals with low unit value are very sensitive to transport costs, and they are often very sensitive to small amounts of deleterious components or differences in physical or chemical behavior. Problems of sampling and grade control change with the genetic type of deposit, with the stage of deposit development and with the size of the information base. Precious metal epithermal deposits (2, 6, 8), because of rapid vertical zonation and erratic lateral distribution of values, have always been difficult to evaluate and maintain grade control and ore reserves. On the other hand, evaluation and grade control are relatively easy in bulk-low- grade deposits (4, 13). However, these deposits generally have a low margin of profit and are sensitive to mining and beneficiaton costs, price fluctuations and political costs. Industrial mineral deposits (5) often must be evaluated on the basis of their behavior, rather than by chemical analysis. Environmental impact generally increases with the scale of the operation, but certain elements or minerals have especially high impact effects (7, 11). In the exploration phase there is no production control of sampling procedures and careful geological observations are particularly essential. The greatest number of problems is related to the oxidized outcrop where the chemical environment of the ore body has changed and the contained values may have been enriched, depleted or values left unchanged (2, 6). Present evidence suggests that gold values may be very mobile under certain conditions (2, 6) and stable under others. Everything must be sampled in detail. Principal values and by-product or deleterious elements may vary dependent upon their position within the soil profile. Such factors as geomorphic position, erosion rate, vegetation, climate, etc., may affect the interpretation (1, 3). During the development phase it is equally easy to overtest, to have "paralysis by analysis," as to undertest (3, 6). Bulk samplng and testing are

Jan 1, 1985

By B. C. Wonsiewicz, W. W. Wilkening

Following a procedure proposed by Wheeler and Ireland, Plane stress yield loci were constructed from Knoob hardness numbers. Basically, six differently oriented hardness measurements were made on three orthogml surfaces through pure poly crystalline magnesium sheet, a magnesium single crystal, and sheet of the magnesium alloys: Mg + 0.5 pct Th, Mg + 4 pct Li, AZ31B, and EKOO. Hardness loci were found to be in poor agreement at small strains (E < 0.05) with loci established by a more rigorous technique. At larger strains (E - 0.10) the agreement is fair, but at this stage in deformation the conventional locus has lost much of the asymmetry that characterizes these anisotropic materials. Two effects which will lead to distortions in the Khn locus are discussed with reference to the geometry of plastic flow during a hardness test. DETERMINING a material&apos;s resistance to multiaxial loading is of interest not only from a structural design viewpoint but also from that of deformation processing. Unfortunately, the determination of the yield locus, although simple in principle, involves tedious procedures if the results are to be at all rigorous.&apos; The idea, first proposed by Wheeler and 1reland2 of determining the yield locus by means of six Knoop hardness impressions along the principal directions in a material has obvious appeal. It is simple, quick, and should be applicable to very thin sheets. If such a technique could be demonstrated to produce consistently reliable results, it would be of interest to both researcher and designer. Lee, Jabara, and ackofen have compared the yield locus determined by Knoop hardness measurements (the Khn locus) to a locus determined by more rigorous techniques. They found good agreement for two titanium alloys at a plastic strain of about 1 pct. The purpose of this paper is to investigate if the Khn locus construction is a reasonable approximation to the locus of a highly anisotropic material. Examples of such materials are magnesium and magnesium alloys which have severely distorted yield loci which in turn reflect markedly dfferent yield strength in different directions.&apos; In pure magnesium, for example, the yield stress in tension along the transverse direction may be four times the yield stress in compression in the same direction and twice the tensile yield stress in the rolling direction. Predicting such large differences ought to serve as a severe test of the Khn locus construction. EXPERIMENTAL PROCEDURES Samples of rolled sheet, 0.250 in. (6.35 mm) thick, of pure magnesium and four magnesium alloys (Mg experimental materials. The pure magnesium together with the lithium and thorium alloys were those used in the study of Kelley and Hosford. The grain size was ASTM number 4 for the pure magnesium and number 6 for the alloys. HARDNESS TESTING The materials were sectioned along the rolling and transverse planes, mounted in a quick setting resin, and mechanically polished. Most of the hardness tests were performed on a surface prepared by electro-polishing (30 pct nitric acid in methanol at 0°C and 20 v) with the exception of the AZ31B and EK00 alloys which were made directly on a metallographically polished surface. However, subsequent hardness tests on the same sample after heavily electropolishing, revealed essentially the same hardness as before. At least twenty Knoop hardness impressions under a 100-g load were made in each of the six orientations shown in Fig. 1. The average hardness number and standard deviation were then calculated for each orientation. CONVENTIONAL LOCUS CONSTRUCTION Yield loci were constructed using a technique described in detail by Lee and ackofen,&apos; in which the flow stress (stress at a given plastic strain) fixes the coordinates of a point on the locus and measurements of the strain ratio serve to establish the slope of the locus at that point. The loading paths which correspond to uniaxial tension or compression tests establish the four intercepts of the locus with the coordinate axes plus one point on the balanced biaxial tension line Tensile testing was performed along the rolling and transverse (r, t) directions. Samples had a uniform rectangular gage length 1 by 4 by 4 in. (25.4 by 6.35 by 6.35 mm) and were deformed at a strain rate of 3.33 x 104 sec-&apos;. The tests were interrupted periodically to unload the sample and measure the plastic strains by means of X-Y post yield strain gages. Compression tests in the rolling, transverse, and through-thickness (r, f, z) directions were performed on 1/4 in. (6.35 mm) cubes at an initial strain rate of 8.33 x sec-&apos;. Lubrication was provided by 0.002 in. (51 pm) Teflon sheet which was renewed after unloading for micrometer measurements used to calculate the strains.

Jan 1, 1970

By T. I. Moore, L. A. Painter

THE electrolytic zinc plant of the American Zinc Co. of Illinois was described by Davidson&apos; in 1944. Since then, improvements as well as expansion of the plant facilities have been made. In order to increase the production of high grade zinc which was needed for war purposes, an expansion program designed to double the slab zinc capacity was started in 1942 and completed in March 1943. This expansion was propagated by a contract between the American Zinc Co. of Ill. and the Defense Plant Corp. The contract included the facilities of the Fairmont City, Ill., property of the American Zinc Co., where a suspension-type roaster with contact acid plant, cadmium distillation furnace, Waelz oxide and densifying plant, and horizontal retort furnaces were installed. The expanded Monsanto, Ill., plant and the additional facilities of&apos; the Fairmont plant were designed to integrate the metallurgical treatment of zinc concentrates for the production of special high grade zinc at Monsanto with the production of acid, cadmium, high grade zinc from furnace skimmings and the Waelz treatment of leach residue at Fairmont. In general, the original flowsheet was not changed, except for the addition of the filtering, drying and reclaiming of leach residue, and the treatment of purification cake for the recovery of copper, cadmium sponge, and zinc. Fig. 1 is a flow diagram of present operations. The original plant facilities, desi-gned for 50 tons daily production of slab zinc, had some units which were more than adequate. Therefore, in expanding the facilities to 100 tons per day, it was not necessary to double all operating components. Table I gives the comparison of the changes made in the unit operating components for the original facilities, 1941, the 1943 expansion, and the 1951 facilities. During the past 11 years a number of improvenients have been made resulting in: 1—an increase in slab production, 2—higher recoveries on the calcine treated, 3—better quality of slab zinc produced, 4—higher current efficiencies, and 5—less man hours Table I. Changes in Operating Facilities Operating Unit 1941 1943 1951 Calcine unloading (pneumatic), 10 tons per hr 12 calcine unloading track hpr. and elev., 60 tons per hr 1 Calcine storage, tons 1,000 2,000 2,000 Leach tanks, 35 vol. tons. No. 3 5 6 slurry mixing 6x6 ft stainless tank, No. 1 Ball mill. 4.5 rt x 16 in. conical. No. 1 CLassifier duplex, No. 1 1 Thickeners. 50 it diam. No. 2 9 2 Filter thickeners, sq ft &apos;-- Moore filters, sq ft 5.760 11,520 Drum filters, 10 ft diam x 16 ft, No. 3 3 Rotary arlers, No. 1 2 1st stage Cu-As purificatlon tank. 90 vol. tons, No. 3 Solution heaters, No. 3 Filter press, 30x30 bronze, No. 4 Zinc dust purification tanks, 45 vol tons. No. 3 5 4 Filter press, 36x36 bronze, No. 3 5 3 Cadmium recovery plant: Process tank. No. 5 2 Cake roaster, 20 ft diam x 4 hearth. No. 1 Filter press, 24x24, No. 4 1 Sponge wash box, 4x6 ft, No. 1 Evaporative cooling unit (vacuum), No. 1 Purified storage tank, vol. tons 400 400 400 Cell acid storage, vol. tons 400 400 400 Electrolytic cells, No. 180 372 372 Cell room ventilation, cu ft per min 35,000 125,000 125,000 Cell cooling water. gal per min 1,500 2,300 2,300 Deep well 16 in. x 95 ft, 1500 gal per min, No. 2 3 3 Melting and casting furnace, 130 ton. No. I Furnace fume scrubber unit, No. 1 Dross drums, No. 2 Dross roaster, 8 ft diam x 8 hearth, No. 1 Electrolysis power conversion, kw 6,250 23,750 23,750 Power transformers, 13,800/440, kva 1,000 1,500 2,000 Steam boilers fire tube, 15 psi, lb per hr 12,000 18,000 18,000 Steam boilers water tube. 125 psi, Ib per hr 30,000 Air compressor, 2 stage. 300 cu ft per min. 100 psi, No. 1 2 Air compressor, 1 stage, 300 cu ft per min, 20 psi, No. 1 Vacuum pumps, 18x7, 720 cu ft per day, No. - - . Vacuum pumps, 24x11, 1.633 cu ft per day, No. 3 3 Building area, sq ft 60,854 113,568 115,000 per ton of metal produced. In the summer of 1944, the "reverse" leaching process was placed in operation and since it has been described,&apos; no further description will be given. Other facilities and changes which have contributed to the process improvements were the scrubbing of fume from the melting and

Jan 1, 1953

By Ernest R. Dickie

BRIEFLY, the ore body of the Bagdad Copper Corp., Bagdad, Ariz., is a monzonite porphyry carrying copper values fairly evenly distributed from the surface down through the primary zone. Tabular in shape, the ore body extends over several hundred acres. The oxidized zone averages about 60 ft thick and assays about 0.50 per cent copper. Under this is the chalcocite zone, or the zone of secondary enrichment, which averages about 100 ft in thickness and assays about 1.4 per cent copper. Under this zone lies the primary zone which extends in places to a known depth of about 150 ft and averages in grade about 0.60 per cent copper. Several years ago the block-caving method of extracting the ore from the chalcocite zone was installed. Then it was necessary to draw only about 250 to 300 tons per day, the capacity of the old milling plant. Early in 1943 the new 2500-ton concentrator was put into production. Drawing ore from the developed stopes in sufficient tonnage to furnish the mill at capacity proved unsuccessful in more ways than one. First, drawing the ore at an accelerated rate caused a large amount of dilution, there-by lowering the grade, and also caused funneling through to the surface. The surface material was detrimental to milling metallurgy and development of these stopes was costly per ton of ore extracted. The grade of ore decreased. making it impossible to maintain a mill head of over 0.9 per cent copper. The

Jan 1, 1947

By Shiou-Chuan Sun

THIS paper presents the design and operation of a frothmeter capable of measuring the frothing characteristics of pine oils and other frothing reagents. The experimental data show that the frothability of pine oil is governed by: 1-rate of aeration, 2-time of aeration, 3-height of liquid column, 4-chemical composition of pine oil, 5-pH value of solution, 6-temperature of, solution, and 7-concentration of pine oil in solution. The effect of mineral particles on the behavior of froth also was studied, and the results can be found in a separate paper.1 The results also show that the relative frothabilities of pine oils in the frothmeter generally correlate with those in actual flotation, provided that other factors are kept constant. In addition to pine oils, the other well-established flotation frothers were tested, and the results are included. In this paper, compressed air frothing is the frothing process performed by means of purified compressed air, whereas sucked air frothing is the frothing process accomplished by purified air sucked into the glass cylinder by a vacuum system. The term vacuum frothing denotes that froth was formed by degassing of the air-saturated liquid under a closed vacuum system. Apparatus The frothmeter, shown in Fig. 1, is capable of reproducibly measuring the volume and persistence of froth as well as the volume of air bubbles entrapped in the liquid and is capable of being used for compressed air frothing, sucked air frothing, and vacuum frothing. Fig. la shows that for compressed air frothing, the apparatus consists of an airflow regulating system, 1-3; a purifying and drying system, 4-8; a standardized flowmeter to measure the rate of airflow from zero to 500 cc per sec, 9; and a graduated glass cylinder, 13; equipped with an air regulating stopcock, 10; an air chamber, 11; and a fritted glass disk to produce froth, 12. The fritted glass disk, 5 cm in diam and 0.3 cm thick, has an average pore diameter of 85 to 145 microns. The pyrex glass cylinder has a uniform ID of 5.588 cm and an effective height of 63 cm. The inside cross-sectional area of the glass cylinder was calculated to be 24.53 sq cm, or 3.8 sq in. For sucked air frothing, Fig. lb shows that the apparatus for compressed air frothing is used again, with the following modifications: 1-compressed air and its regulating system, 1-3, are eliminated; and 2-a vacuum system, 16, equipped with a vapor trap, 15, and a vacuum manometer, 17, is added. The vacuum system can be .either a water aspirator or a laboratory vacuum pump. Any desired rate of airflow can be drawn into the glass cylinder, 13, by adjusting the opening of the air regulating stopcock, 10. The sucked air stream is cleaned by the purifing and drying system, 4-8, before entering the glass cylinder, 13. When this setup is used for vacuum frothing, the air regulating stopcock is closed. The frothmeter has been used for almost 3 years and has proved to give reproducible results, as illustrated in Table I. With a magnifying glass and suitable illumination, the frothmeter also can be used to study the attachment of air bubbles to coarse mineral particles.2 Experimental Procedures Except where otherwise stated, the data presented were established by means of the compressed air method. The volume and persistence of froth were recorded respectively at the end of 4 and 6 min of aeration at a constant rate of airflow of 29.3 cc per sec which is equivalent to 71.6 cc per sq cm per min, or 462.6 cc per sq in. per min. The aqueous solution for each test, containing 1000 cc of distilled water and 19.2 ± 0.5 mg frothing reagent, was adjusted to a pH of 6.9 ± 0.2. The volume of froth is expressed as cubic centimeter per square centimeter and is equivalent to the height of the froth column (the distance between the bottom and the meniscus of the froth). The volume of froth was obtained by multiplying the height of froth by the cross-sectional area of the glass cylinder, 24.53 sq cm. Before each test, the glass cylinder, 13, was cleaned thoroughly with jets of tap water, ethyl alcohol, tap water, cleaning solution, tap water, and finally distilled water. The cylinder with stopcock,

Jan 1, 1952