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By Rollyn P. Jacobson

THE town of Pacific, in Jefferson County, Mo., is 127 miles west of St. Louis. Since the area lies entirely on the flood plain of a cutoff meander of the Meramac River, it was considered a likely environment for accumulation of commercial quantities of sand and gravel. Excellent transportation facilities are afforded by two major railways to St. Louis, and ample water supply for washing and separation is assured by the proximity of the river. As a large washing and separation plant was planned, the property was evaluated in detail to justify the high initial expenditure. An intensive testing program using both geophysical and drilling methods was designed and carried out. The prospect was surveyed topographically and a 200-ft grid staked on which electrical resistivity depth profiles were observed at 130 points. The Wenner 4-electrode configuration and earth resistivity apparatus" were used. In all but a few cases, the electrode spacing, A, was increased in increments of 11/2 ft to a spread of 30 ft and in increments of 3 ft thereafter. Initial drilling was done with a rig designated as the California Earth Boring Machine, which uses a bucket-shaped bit and produces a hole 3 ft in diam. Because of excessive water conditions and lack of consolidation in the gravel there was considerable loss of hole with this type of equipment. A standard churn drill was employed, therefore, to penetrate to bedrock. Eighteen bucket-drill holes and eight churn-drill holes were drilled at widely scattered locations on the grill. The depth to bedrock and the configuration will not be discussed, as this parameter is not the primary concern. Thickness of overburden overlying the gravel beds or lenses became the important economic criterion of the prospect.** The wide variety and gradational character of the geologic conditions prevailing in this area are illustrated by sample sections on Fig. 2. Depth profiles at stations E-3 and J-7 are very similar in shape and numerical range, but as shown by drilling, they are measures of very different geologic sequences. At 5-7 the gravel is overlain by 15 ft of overburden, but at E-3 bedrock is overlain by about 5 ft of soil and mantle. Stations L-8 and H-18 are representative of areas where gravel lies within 10 ft of surface. In most profiles of this type it was very difficult to locate the resistivity breaks denoting the overburden-gravel interface. In a number of cases, as shown by stations M-4 and H-18, the anomaly produced by the water table or the moisture line often obscured the anomaly due to gravel or was mistaken for it. In any case, the precise determination of depth to gravel was prevented by the gradual transition from sand to sandy gravel to gravel. In spite of these difficulties, errors involved in the interpretation were not greatly out of order. However, results indicated that the prospect was very nearly marginal from an economic point of view, and to justify expenditures for plant facilities a more precise evaluation was undertaken. The most favorable sections of the property were tested with hand augers. The original grid was followed. In all, 46 hand auger holes were drilled to gravel or refusal and the results made available to the writer for further analysis and interpretation. When data for this survey was studied, it immediately became apparent that a very definite correlation existed between the numerical value of the apparent resistivity at some constant depth and the thickness of the overburden. Such a correlation is seldom regarded in interpretation in more than a very qualitative way, except in the various theoretical methods developed by Hummel, Tagg (Ref. 1, pp. 136-139), Roman (Ref. 2, pp. 6-12), Rosenzweig (Ref. 3, pp. 408-417), and Wilcox (Ref. 4, pp. 36-46). Various statistical procedures were used to place this relationship on a quantitative basis. The large amount of drilling information available made such an approach feasible. The thickness of overburden was plotted against the apparent resistivity at a constant depth less than the depth of bedrock for the 65 stations where drilling information was available. A curve of best fit was drawn through these points and the equation of the curve determined. For this relationship the curve was found to be of the form p = b D where p is the apparent resistivity, D the thickness of overburden, and b a constant. The equation is of the power type and plots as a straight line on log-log paper. The statistical validity of this equation was analyzed by computation of a parameter called Pearson's correlation coefficient for several different depths of measurements, see Ref. 5, pp. 196-241. In all but those measurements taken at relatively shallow depths, the correlation as given by this general equation was found to have a high order of validity on the basis of statistical theory.

Jan 1, 1956

By Lucien Eaton

THE use of filling in mines is less common in the United States than it is in Europe, where in some places it is required by law. In most cases the filling is placed by hand, and the material used for this purpose is the waste from development and that sorted from the ore in the stopes. When these sources provide an insufficient supply, additional rock must be quarried on surface or mined underground, or some other material :st be used. In different parts of the world sand, clay, gravel, culm, nulated slag, mill tailings, and even ashes, have been used as filling material in place of or in conjunction with rock. Of all the materials used for filling the best is probably clean sand. Gravel, finely crushed rock, granulated slag and coarse mill tailings are almost as good, and the methods used for placing and confining sand will apply equally well to any of these. The advantages of sand are its comparatively slight compressibility and the ease, economy and convenience with which it may be placed. On account of the voids, which necessarily occur in fills made of coarse waste, such fills will compress 10 to 25 per cent before they develop their full strength, whereas clean sand seldom compresses more than 5 per cent. Sand is especially desirable when practically complete filling is required, and sand derived from mill tailings, especially when not thoroughly cleaned, has been remarkably effective in sealing off and extinguishing mine fires. When natural sand is available on surface, or when it can be obtained from the mill tailings or tailings dump, the cost of using this material for fill will probably be considerably less than that of rock. In this paper it is not proposed to discuss all methods of filling, butt to describe some of the methods used for placing sand fill and to make a brief comparison of their merits.

Jan 1, 1932

By J. Moore Samuel

INTRODUCTORY BEFORE the year 1909, no measurements of dust losses and flue gases had been made at the Copper Queen Reduction Works, at Douglas, Ariz. At that time the "unaccounted" loss of the smelter had reached a figure, that drew attention to the possibility of large stack losses. The measurement of dust losses had not been studied much at that time, and estimates of dust losses, with a few exceptions, were the results of tests by what has been termed "chemical methods," that is, the aspiration and filtration through cotton, wool or some similar medium of a few liters of gas, the dust being weighed on a chemical balance, and the volume of gas computed from the volume of aspirator water. The possible error of this method is enormous, and the probable error much too large for reliable results. Since the object of these tests was to discover not only the extent of the dust losses, but also the possibility of profitably reducing the same, it was decided that the method adopted must have the following characteristics: 1. The sample of gas taken for filtration must be representative of the whole volume of gas, that is to say, it must have the same dust content. This condition will be fulfilled in all cases if the gas sample is drawn off without change of rate of flow. Then it will contain the same proportion of entrained or suspended particles of dust as the original gas. In the case of flue gases which contain only fume, at a temperature above or near the sublimation point, this condition need not be adhered to since the fume will not behave as entrained particles, but more nearly as a true gas. Consequently the gas sample in this case only may be drawn off at any rate of flow. 2. The gas sample taken must be large enough (a) to yield sufficient dust to permit of accurate chemical and physical examination; (b) so that the ratio of the total volume of gas passing through the flue to the volume of gas sample taken shall not be too large.

Jan 6, 1916

By Richard W. Lodge

The following work, performed by Mr. W. A. Tucker, of the class of 1893, in the mining department of the Massachusetts Institute of Technology, seems to me to be worthy of publication. I believe it has always been considered that the presence of arsenic especially interferes with the extraction of gold by the cyanide method. Mr. Tucker's work, although made on a laboratory scale, certainly seems to disprove this view, and to show that even with a very large percentage of arsenic present in the ore, a high extraction may be obtained without an excessive consumption of potassic cyanide. The ore from which the concentrates were obtained was a gray argillaceous schist. and slate, with stringers and veins of quartz running through it. It carried free gold and about 12 per cent. of sulphides. The ore was crushed with stamps; the free gold was collected in the ordinary way on silver-amalgamated copper plates; and the sulphides, which consisted chiefly of arsenopyrite and pyrite, with very small amounts of galena and chalcopyrite, were concentrated and collected by means of a Frue vanner. A carefully-taken sample gave: Gold,........6.17 ounces per ton. Arsenic,.......30.6 per cent. The latter figure would correspond to about 66.5 per cent,. of arsenopyrite in the concentrates. The work to be done was outlined as follows: 1. Sizing the concentrates; 2. Assaying the different sizings; 3. Treating these different sizings with ECy of different degrees of strength for different periods of time.

Jan 1, 1896

By Avnulf Muan, P. V. Riboud

The effect of Cr2O3 on melting relations of iron oxide at oxygen pressures slightly above those prevailing in contact with metallic iron has been determined. Liquidus and solidus temperatures of wüstite are raised by the addition of Cr2O3, from 1385°C for pure iron oxide to 1420°C at the peri-ledie point where wüstite, iron chromite, liquid, and gas coexist in equilibrium under the atmospheric conditions used in the present investigation (CO2/H2 = 1). It has been shown in a previous investigation1 that the liquidus and solidus temperatures of iron oxide are drastically increased by the addition of Cr2O3 under the relatively oxidizing conditions prevailing in air. This is to be expected in view of the easy substitution of cr3+ for Fe3+ in crystalline oxide structures which are stable at high oxygen pressures, as demonstrated for instance by the completeness of the solid solution series Fe2O3-Cr2O3 at high temperatures (>1000°C). The stable phase of iron oxide at oxygen pressures approximating those prevailing when metallic iron is present is wüstite. This phase, although commonly represented by the simplified formula FeO for sake of convenience, in reality has a defect structure in which a part of the iron ions are present as Fe3+. It is to be expected that at least a limited amount of cr3 ions will substitute for Fe in this structure when Cr2O3 is added to wüstite. Depending on the ease of this substitution in comparison with that of cr3 substitution for Fe in iron oxide-Cr2O3 liquids under the same atmos- pheric conditions, the liquidus and solidus temperatures of wüstite may increase or decrease upon addition of Cr2O3. The methods of establishing these melting relations and the results obtained are presented in the following. I) EXPERIMENTAL METHOD 1) General Procedure. The quenching technique was used in this study. Oxide mixtures were heated at chosen constant temperatures in an atmosphere consisting of equal parts of CO2 and H2 until equilibrium was established among gas and condensed phases. The samples were then quenched in mercury to room temperature, and the phases present were determined by microscopic and X-ray investigation. 2) Preparation of the Mixtures. Starting mixtures were prepared by weighing and thoroughly mixing Fe2O3 and Cr2O3, or wüstite and Cr2O3. The Fe2O3 and Cr2O3 used were "Baker Analyzed" reagent grades, whereas wüstite of composition was synthesized by reducing Fe203 at 1325°C in an atmosphere consisting of equal parts of CG andHz. In order to avoid contact with crucibles, the equilibration runs were made with small pellets suspended from thin (-0.004-in.) platinum wires. Mixtures made from FOs and Cr203 were readily pelletized at a pressure of 500 atm in a 9.5-mm die, whereas mixtures made from wüstite and Cr203 when treated identically were too weak for handling. In order to obtain a stronger product, these pellets were sintered by heating for 2 min at -1200°C in the same atmosphere as was subsequently used for the equilibration runs (CG/H2 = 1:1). During the sintering, these pellets were wrapped in thin (0.0004-in.) platinum foil, which was stripped off before the equilibration runs. In order to reduce the time needed for equilibrium to be attained, preliminary equilibration of relatively large pellets of each mixture was carried out at -1200°C for 4 to 12 hr. Smaller pellets

Jan 1, 1964

By W. H. Emmons

ALTHOUGH gold is one of the rarer metals, it is widely distributed; it is found on all of the continents and in each of the grand metallogenic provinces of the earth. It is prominent particularly in the shield areas of the earth; these areas have produced a large part of the world's lode gold and in most of them gold lodes are more important than the lodes of other metals. The Scandinavian shield is the only one that has not produced much gold. Nearly all of the world's gold has been derived from lodes and from sands and gravels where gold placers formed by the destruction of lodes. The gold derived from magmatic segregations, from pegmatites and from contact metamorphic deposits is quite subordinate to that derived from auriferous lodes. The lodes include all veins and related deposits that are formed by hot waters that move along fissures or other openings and that deposit vein matter in the fissures and by replacement of the country rocks along the fissures. All of the shield areas of the earth are characterized by large areas of granitic rocks including granitic gneisses, granodiorites and other acid intrusives which here are included in the general term "granite." The granites are intruded into schists, ancient lavas and other rocks which here are designated as the "invaded" rocks. The granites are parts of what once were great batholiths: that is, they are the remaining portions of great deep-seated bodies that slope outward, have very irregular roofs and so far as known have no floors but extend downward to great though unknown depths. Some of them are scores or hundreds of miles across and contain islands or "roof pendants" of the invaded rocks at places where the roofs of the batholiths were low-that is, where erosion has not yet completely unroofed the batholiths.

Jan 1, 1932

By R. B. Moffitt

INTRODUCTION In recent times the continuing depletion of high grade mineral deposits and the massive increase in raw material consumption have forced the metal mining industry to exploit ore bodies of lower and lower grades. To obtain a satisfactory financial return from these deposits, there has been the concurrent and evident trend towards increasing the size of operations to obtain benefits from the economies of scale. The evaluation, planning, and design of these large scale open-pit operations, so as to yield the maximum possible return on investment, is an extremely complex, iterative procedure. With profit margins trimmed, "small" errors can become much more significant and with exploration costs spiralling, accurate and rapid evaluation is essential. It demands a sophistication and precision in the evaluation process unheard of ten years ago. What follows attempts to describe the need to thoroughly plan the overall evaluation programme such that duplication of effort is avoided and all relevant information is systematically recorded from the outset of exploration. The final section of the paper takes a realistic case study to illustrate the significance of pit slope angles on the design of the final pit and the economics of the total project. THE EVALUATION PROGRAMME The team, (for a team effort it must be), that is charged with the responsibility of conducting the evaluation exercise, has the difficult task of placing values on a multitude of independent and inter-related variables. Each variable has some economic significance; the degree of significance varying according to the metal sought, the environment in which it occurs, the vagaries of the market place, to name but a few of the problems facing the project team. From this maze of variables, the team must identify those that have the most critical influence on the overall economics of the proposed venture. Investigations must then be set in motion to quantify these controlling factors more precisely. It is important to recognize that such investigations form part of the evaluation programme and require monitoring for both timing and cost as the whole exercise of evaluating the project continues. To add to the difficulties, the economic significance of any particular variable may change during the course of the programme.

Jan 1, 1972

By Robert C. Beckstorm

Russia produced over one-half of the world's petroleum in 1901. It dropped to a low figure in 1920 during the reorganization of the new government. Since then it has had a remarkable growth under the constant demands from the Central Bureau at Moscow. The five-year plan called for the development of all industries, many of which had permitted their equipment to gat out of repair or become obsolete, so that when the magic wand of authority demanded that they double, triple or quadruple their former production they looked to the oil industry for aid. This plan made necessary the building of new factories, dams and power stations; the developing of mines and agriculture, and in many places the building of cities and railroads. Exports were the solution and petroleum was the logical one to carry the load of development of the more backward industries. It had a ready market and fields located advantageously for transportation, which was cheap, and there was sufficient oil to meet the market demands at that time, as domestic consumption was not great. The building program demanded new and modern machinery and technical aid from abroad. FIG . 1.-PETROLEUM Money was necessary and petroleum was the impor- 1925-1931. PRODUTION IN RUSSIA tant product of exchange. This accounts for the rapid development of the old fields, the search for new ones and the building of refineries and transportation facilities. Fig. 1 shows the advance in production since 1925. There has been a. steady increase since 1920, and with the improved drilling equipment and improved methods it will increase as long as the now proved fields continue to produce new wells. The fields of Baku and Grozny have yielded 95 per cent of this production. The Cara Chukur field, which is being developed at the present time, is an extension of the Surakany at Baku and may be considered a part of the old field. New fields are being

Jan 1, 1932

By P. D. Zemany, G. W. Sear, B. W. Roberts

Vanadium metal is embrittled by hydrogen at a temperature as low as 250°C when held in the presence of manganese metal and water vapor in a rough vacuum. It is established that the property changes are caused by the catalytic decomposition of water vapor at the vanadium surface and the diffusion into and solution in the vanadium of the resultant hydrogen. It is found that manganese is a necessary component of the catalyst. The manganese is transported in the vapor phase by an unknown molecule. A deuterium tracer experiment demonstates the role of water vapor in the embrittle-ment process. VANADIUM metal foils were observed to become embrittled' at a temperature of about 300 °C when held in the presence of manganese metal and a small amount of moist air, This paper describes the investigation to find the embrittling agent and an understanding of the relatively low temperature reactions that are involved. Experimental The vanadium metal foil used was prepared by cold-rolling and pack-rolling 32 mil sheet" in a series of steps down to 1 mil foil. The original observation was confirmed by sealing vanadium foils of 3 x 10 sq cm into individual Pyrex tubes with manganese powder† and a con- trol tube containing only the vanadium foil. These tubes were evacuated to 10 -5 mm Hg without baking and sealed. After heat treatment for 200 hr at 300°C, the control foil showed no change in duetility, whereas the foil contained in the manganese— containing tube was embrittled. The visual appearance of each was unchanged. A series of Pyrex sample tubes, about 2.5 cm diam and 25 cm long, were prepared, each containing a 3 x 10 sq cm piece of foil and 5 g manganese powder at the lower end of the tube. By reducing the time of anneal and the temperature of these samples, it was found that embrittlement could be created at 250°C in a time as short as 1 hr. Since the vanadium metal used here has been drastically cold-worked by rolling, it is assumed that it contains a maximum number of dislocations. To check the possible necessity of dislocations in this low temperature reaction, a vanadium foil sample was annealed in Vycor for 2 hr at 800°C to re crystallize and reduce the dislocation concentration. Metallographic examination showed grains which were not visible before annealing. The embrittlement procedure was carried out at 300°C and 3 hr. Upon checking the foil no embrittlement was observed. Further experiments demonstrated that about 6 hr at 300°C are required to create embrittlement in the foil. This delay in the onset of embrittlement in the vanadium foil suggests but does not prove that dislocation channels play a role in the embrittlement phenomena. If manganese metal is necessary for this low temperature embrittlement, do other elements in the transition metals group yield the same result? To check this qualitatively, a group of elements of similar atomic radii were obtained and sealed as before into Pyrex tubes with a sheet of vanadium foil. These tubes were annealed at 250°C for 6 hr and included (with radii)-2 A1 (1.4A), As (1.25A), Be (1.2A), Co (1.25A), Cr (1.45A), Cu (1.25A), Fe (1.25A), Ga (1.2A), Ge (1.25L%), Mn (1.3A), Ni (1.25A), Si (1.2A), Ti (1.45A), Zn (1.3A), air, H,O, 10 cm Hg of dry hydrogen, and MnO, powder. Upon testing the above sample foils for brittleness, only the manganese-containing tube yielded a brittle foil. Manganese Transport—To eliminate contact of manganese metal powder and vanadium foil, sample tubes were prepared with fritted glass barriers. The embrittlement reaction was still found to occur. Thus, the mode of transfer of manganese is certainly vapor transport. A vanadium foil was embrittled by this mechanism in an evacuated Pyrex tube for 8 hr at 300°C. By means of X-ray fluorescence analysis,' the amount of manganese added to the surface was established at 5 ±2 x 10 -6 g per sq cm. Since the average rate of manganese deposition is known, an effective average pressure of an assumed carrier compound can be computed. ___ P = M/T v2p mkT

Jan 1, 1959

By C. E. Sims, C. A. Zapffe

AN investigation of the behavior of inclusions in steel several years ago1 led to the conclusion that some of the commonly occurring inclusions in steel have appreciable solubilities, particularly in liquid steel. In the belief that further study and clarification of this matter was warranted, a laboratory study of oxides in liquid steel was started. These oxides are generally the result of deoxidation treatment, and the basis of an understanding of their behavior must be, therefore, the behavior of the deoxidizer in liquid iron. The Fe-Si-O system was selected for the first study, and the apparatus used and experiments conducted are described herein. APPARATUS The apparatus is shown in Fig. I and the system is shown by diagram in Fig. 2. Furnace Atmosphere Commercial hydrogen (1) passes through an orifice (2) into a manometric system that measures the tankside pressure (3) and the back pressure (4) in the system. A water trap (5) guards against excess tankside pressure. A by-pass with stopcocks (6 and 7) is provided, so that the hydrogen can be routed directly from the tank to the furnace if desired. When stopcock 7 is closed and stopcock 6 is open, the gas proceeds through the conditioning train, of which the first unit is a furnace (8) that contains platinized asbestos at 350°C. The temperature is measured by a thermo-couple and potentiometer (9) and is controlled by a slidewire resistance (10). In [ ] this furnace free oxygen is converted to water vapor. The exiting gas passes over a water bath (11) kept slightly below boiling temperature by an auxiliary heating unit (12). This unit also heats a surrounding copper coil (13) containing water, and the heated water rises through a collar (14)

Jan 1, 1942

By Phillip B. Bucky, Fred D. Wright

The present known petroleum reserves are limited, and unless important new fields are discovered the Nation will be dependent, in the not too distant future, upon imports or upon synthetic liquid fuels to supplement domestic petroleum supplies. As a national defense measure, it would appear desirable to develop a substitute source of liquid fuels within the borders of the country if new discoveries of petroleum should Prove disappointing. Congress undoubtedly had this in mind when it passed the Synthetic Liquid Fuels Act (78th Congress, approved April 5, 1944). The act directed the Bureau of Mines to construct and operate demonstration plants for producing synthetic liquid fuels from coal and oil shale, and from forestry and agricultural products. As a part of this program, the Bureau of Mines has built a demonstration plant at Anvil Points, near Rifle, Colo., for retorting the oil shale, and has developed a mine to supply the plant with oil shale. At the beginning of mining operations, the physical qualities of the oil shale, which would have a bearing upon the selection of mining methods and practices for exploiting the deposits, were largely unknown. A comprehensive mining-research program has been set up to determine the best methods and practices to follow to obtain the lowest overall practicable mining cost for producing the oil shale on a large scale. Unusually low mining costs will be necessary for shale oil to be produced commercially. Consideration now is being given to exploiting a series of flat-lying beds 70 ft thick by a room-and-pillar method of three benches with the advance heading at the top. This report is one of a series giving the results obtained in research on mining problems, The structure and physical qualities of the oil shale indicate that the 70-ft interval of the oil-shale measure can be safely mined in open stopes; studies indicate that this method would be the most economical one to use.' As labor will be a major item of expense, the largest equipment that could be operated efficiently in the workings would be required to obtain the lowest practicable mining Cost. It Was therefore desirable to know the maximum safe span of unsupported rooms and the size of pillars necessary to support the overburden. This paper describes the work done at the Columbia School of Mines Barodynamic Laboratory in determining the maximum safe unsupported roof spans and the minimum safe pillar dimensions for the oil-shale mine at Rifle, Colo.

Jan 1, 1949

By G. R. Fritterer

Investigators in the field of temperature measurement have long sought a thermoelectric couple fulfilling the following requirements: 1. It should be useful up to and including high industrial temperatures; i. e., 1000 to 1800 C. 2. Its thermoelectric variation with temperature should be linear and be maintained after heating to high temperatures for long periods of time. 3. It should be reproducible; i. e., different couples of the same elements should have similar calibration curves. 4. Its thermoelectric power should be large so as to allow the industrial use of rugged recording instruments. 5. Chemical reactions with, and physical changes within the elements of the couple should not alter its calibration. No thermocouple proposed to date exhibits simultaneously all of these characteristics, whereas the couple about to be described fulfills all requirements to a satisfactory degree. New Thermoelectric Materials A thorough survey of the literature on thermoelectricity revealed that present-day thermocouples could not meet the specifications mentioned above because their thermoelements are metallic. Metals have a marked tendency to deteriorate chemically and their melting points limit their use to low temperatures. Refractory substances, however, are usually resistant to chemical attack and are quite stable at high temperatures. Hence a survey of refractory substances having thermoelectric possibilities was made. One class of thermocouples considered was that in which carbon and a carbide of some metal or nonmetal were the thermoelements. Previous investigators neglected to study this field but certain recommendations were made by them for the use of couples in which carbon served as one element. These proposals are listed in Table 1. The couples suggested are unsatisfactory because of their low thermoelectric powers, the low melting points of their metallic elements, etc. The

Jan 1, 1933

By E. E. McGinley, L. D. Woodworth

DURING the past several years has occurred what, in the light of future events, may aptly be called the rebirth of the acid Bessemer process. The increased attention given to the technical and metallurgical details involved in the production of Bessemer steels has been exceedingly fruitful, and indicates the value of further research and plant development. In times like these, when the steelmaking capacity of the country is operating at a maximum rate to supply materials for the national defense program, it behooves the Bessemer operator not only to strive to increase production but also to maintain a high standard of quality. The opportunity is ripe, it seems, to recapture fields of application once considered the birthright of Bessemer steels, but supplanted in recent years by open-hearth grades. This involves cooperation all along the line, from the blast-furnace operator to the metallurgical contact man and salesman. The metallurgist's part in this program involves the study of the many steelmaking variables and the measures necessary to ensure constancy in the finished product. It is equally important that the knowledge gained be disseminated widely to ensure the wise application of Bessemer steels in new fields. The merits of Bessemer steels for certain work are well understood. The combined properties of good weldability, machinability and stiffness are unique and fully explain the strong entrenchment of Bessemer steels in certain fields; e.g., skelp for small butt-weld conduit, screw steels machined in automatics, and certain tinplate applications. It is the purpose of this paper to review briefly the physical properties of Bessemer steels as contrasted with those of open-hearth steels, to discuss control measures now employed in the making of Bessemer steel, and to consider the advantages derived from the use of these control measures. PHYSICAL PROPERTIES OF BESSEMER VS. OPEN-HEARTH STEELS A number of Bessemer blows and open-hearth heats were tested for tensile strength, ductility and impact strength. The steels selected were confined to sections from ¾ to 1 ¼ -in. diameter, inclusive, and the carbon content covered was sufficient to yield parallel ranges in ultimate strength for the comparison. Other factors, such as the extent of deoxidation of the steel and variations in chemistry, were kept as comparable as possible. Machined test pieces of 0.505-in. diameter with an 8-in. gauge length were pulled. The data obtained are shown in Fig. 1, ultimate strength being plotted against carbon content. This graph shows that for equivalent carbon content Bessemer steel has on the average 15,000 lb. per sq. in. greater tensile strength and, conversely, for the same tensile strength Bessemer steel requires on the average 0.14 per cent less carbon. The average phosphorus content for the Bessemer steel was 0.090 per cent,

Jan 1, 1941

By F. R. Archibald, F. C. Jackson

The. prospect of winning aluvinum from clay was recorded almost a century ago at a time when the metal was no more than a curiosity.$ As the industry developed, and it has probably developed faster than that of any other metal, the expanding need for raw materials was adequately met by the ample supplies of bauxite ore. As with the other metals older in industry, however, lower grade ores have gradually entered the raw-material field through improvements in ore dressing, insufficienoy of high-grade ore supplies, favorable geographic location, or national necessity for domestic supply. So with aluminum, or alumina, which has been established as the requisite intermediate, the time may have come when a satisfactory process, with favorable location and suitable raw materials, can hold a sound place both in metallurgy and economics. It is the purpose of this paper to describe the Ancor process and its proposed application in treatment of clay in a plant now under construction at Harleyville, South Carolina, by the Defense Plant Corporation. Development of the AncoR Process The Ancor process has developed through successive stages of laboratory investigation, pilot-plant demonstration using neph-eline syenite and pilot-plant demonstration using kaolin-type clay from South Carolina, and is now in preparation for unit trial on an operating plant basis using the latter material. The laboratory studies were carried out over a number of years in the laboratory of the American Nepheline Corporation in Rochester, N. Y., and for the same company in the ore-dressing laboratory of Beattie Gold Mines, Que. Ltd. at Dupar-quet, Quebec. Both companies are associated with Ventures Ltd., Toronto, and its associated American companies. The work was originally undertaken with a view to recovery of alumina and alkalies from nepheline syenite as an adjunct to the American Nepheline Company's established business in the glass and ceramic trades, but as a process developed the possibility of application to clay and other aluminous raw materials became apparent and the laboratory studies were broadened to include these as well. Under the more pressing impetus of wartime needs and possibilities, pilot-plant operations were undertaken at the Canadian Bureau of Mines Ore Dressing Laboratories in Ottawa, and for purposes of demonstration under joint sponsorship of the Canadian Bureau of Mines, The American Nepheline Corporation, and The Aluminium company of canada Ltd. Upon completion of this program, of

Jan 1, 1944

By D. Muraoka

Introduction Soda ash, anhydrous sodium carbonate, is produced from underground trona deposits occurring in the Green River Basin of southwestern Wyoming. Stauffer Chemical Co. of Wyoming, a jointly owned subsidiary of Stauffer Chemical Co. and Rocky Mountain Energy Co., mines the trona and processes it into high-purity soda ash. Stauffer Wyoming has been in operation since 1962 with a current production capacity of about 1.8 Mt (2 million st) per year of soda ash. The refinery has five parallel operating trains using the monohydrate process which is a series of chemical processing unit operations described below. Screening and Crushing The mined trona is brought to the surface in two counterbalancing ore skips. The ore is initially screened with refinery feed (less than peagravel size material) entering the process. Oversize is conveyed to an outdoor stockpile. Ore is recycled from under the stockpile via cone feeders as the refinery needs require. The ore is conveyed to hammer type crushers and screened. The refinery feed enters the process and the oversize is recycled to the crushers. Calcining The first step in refining trona to soda ash is calcining the trona ore. This is accomplished in concurrent flow, rotary kilns that are direct fired with natural gas. [2 (Na CO NaHCO 2H O) Heat 3Na CO + 5H20 + CO 2 3~3~ 2 ~~2 32] The trona ore is fed to the kiln at the burner end and is intimately mixed with the hot exhaust gases from the burner. Direct contact with the flame is avoided. The ore moves down the kiln by gravity and rotation aided by the kiln's internal lifters. The exhaust gases are cleaned to 99 + % particulate removal and discharged to the atmosphere. Dissolving the Calcined Trona The calcined trona is conveyed from the kiln discharge to a rotary drum dissolver where it is mixed with water and weak solution (unsaturated solution of calcined trona in water). The calcined trona is soluble whereas the impurities, primarily shale, are insoluble. The discharge from the dissolver is a slurry containing saturated solution (about 30% dissolved calcined trona in water), some undissolved calcined trona, insoluble impurities, and organic impurities. The dissolver discharge enters a rake classifier that makes the first solid/liquid separation in the process by removing the heavy undissolved material from the saturated solution. This undissolved material is conveyed to a second rotary drum dissolver and mixed with water to dissolve any remaining calcined trona. The secondary dissolver discharges to a second rake classifier that separates the solids from the liquid. The solids are now primarily insoluble impurities with very little unrecovered calcined trona. These wastes are conveyed to evaporation ponds for disposal. The liquid from the secondary rake is recycled to the primary dissolvers' weak solution system. Returning to the primary rake classifier, the saturated solution which contains suspended insoluble muds is pumped to a thickener. Flocculant is added to aid settling of the suspended muds. The flocculated muds are collected at the bottom of the thickener and pumped to vacuum cloth filters. The adhering saturated solution is separated from the muds that remain on the filter cloth. The recovered solution is returned to the dissolvers' weak solution system. The muds are reslurried and pumped to the evaporation ponds for disposal. Saturated solution, containing some suspended insoluble muds along with the organic impurities, overflows the thickener. Filtering the Saturated Solution The saturated solution overflowing the thickener enters a holding tank where it is pumped to a bank of pressure leaf filters. The suspended muds are captured on the filter leaves while the cleaned saturated solution is pumped to polishing filters. The polishing filters are also leaf pressure type, intended to remove any suspended solids that may pass the primary filters. Organic impurities are removed with activated carbon. The purified solution is now free of insoluble muds and has most of the organic impurities removed. Crystallizing and Drying the Monohydrate The purified saturated solution is pumped to evaporative crystallizers. The solution is circulated from the crystallizer vessel through a heat exchanger. Indirect contact with steam in the heat exchanger causes the saturated solution to boil, thus crystallizing the soda ash in its monohydrate form. Slurry crystal density is maintained in the crystallizer by simulta¬neous feed of fresh saturated solution and drawoff of the slurry.

Jan 1, 1986

We have received from L. S. Cates, the following translation, by S. W. Mudd, of early mining methods in India: In Herodotus one finds a description how Darius by aid of his good horse and his good groom Oebares got himself the Kingdom of the Per-sians. He then set up in Persia twenty satrapies assigning to each a governor and fixing the tribute which was to be paid to him by the several nations. The following description of the method of getting the gold demanded of the Indians as tribute is copied directly from Book III Thalia, paragraphs 94 to 105 omitting the diversions of Herodotus which in one case consisted of a lapse of two pages following a semicolon before the author returned to the subject. The Indians, who are more numerous than any other nation with which we are acquainted paid a tribute exceeding that off every other people, to wit, three hundred and sixty talents of gold-dust. The way in which the Indians get the plentiful supply of gold, which enables then to furnish year by year so vast an amount of gold-dust to the King, is the following: Eastward of India lies a tract which is entirely sand. Here, in this desert, there live amid the sand great ants, in size somewhat less than clogs, but bigger than foxes. The Persian king has a number of them, which have been caught by the hunters in the land whereof we are speaking. These ants make their dwellings under ground, and like the Greek ants, which they very much resemble in shape, throw up sand-heaps as they burrow. Now the sand which they throw up is full of gold. The Indians, when they go into the desert to collect this sand, take three camels and harness them together, a female in the middle and a male on either side, in a leading-rein. The rider sits on the female, and they are particular to choose for the purpose one that has just dropped . her young; for their female camels can run as fast as horses, while they bear burdens very much better.

Jan 12, 1919

By Thomas Crowe

Much has been written upon the precipitation of metals from cya-nide solution by zinc. We often read of the many factors that influence precipitation, such as zinc surface, purity of zinc, percentage of lead, temperature of solutions, strength of solutions in cyanide or alkali, etc. Little do we hear, however, of the part that oxygen plays in precipitation. Caldecott1 says: "As the dissolving of gold is essentially an oxidation process, so its precipitation is one of reduction." All who have studied or worked with cyanide solutions will agree that Caldecott's statement is true. In the cyanide work in the mills of the Portland Gold Mining. Co., we have always found oxygen to be the greatest enemy to precipitation. OXYGEN ANTAGONISTIC TO GOOD PRECIPITATION A few years ago, while making some experiments on the effect of pressure upon the dissolving rate of gold front our ores, to prove a point, I made some bottle tests under vacuum. The results were surprising, and showed that under vacuum practically no gold dissolved, which confirmed my belief that Elsner's equation was true and also led me to investigate the amount of dissolved air carried by solutions at atmos-pheric pressure. The experiment consisted in partly filling an acid-bottle with mill-solution and connecting it by a rubber hose to a vacuum pump. When the vacuum was suddenly applied, a cloud composed of. thousands of small air bubbles rose out of the solution, showing qualitatveily the . amount of dissolved air that was contained in the solution, and also proving that the relief of atmospheric pressure on the solution permitted this dissolved air to escape.

Jan 8, 1918

By D. W. Lillie

It has been demonstrated that considerable bend ductility exists in bulk specimens of polycrystalline high-purity silicon. The possibility of hot-forming at 1200°C is suggested. EXCELLENT corrosion resistance in many media and low cross section for absorption of thermal neutrons (0.13 barn) would make silicon of interest to nuclear engineers were it not for extreme brittle-ness and the difficulty of fabrication by any reasonable means. The use of silicon for structural purposes also has been considered in view of its light weight and oxidation resistance. Johnson and Han-sen' have investigated the properties of silicon-base alloys and concluded that there was no way of making pure silicon or silicon-rich alloys ductile at room temperature. In view of reports of appreciable ductility in germanium single crystals above 550°C'." and some plastic deformation in single-crystal silicon above 900oC,' the present investigation was undertaken to define more precisely the limits of high-temperature ductility in pure silicon. After this investigation was begun torsion ductility in both germanium and silicon was reported by Greiner." Through the courtesy of F. H. Horn, a small bar of cast extra high-purity silicon was obtained and small bend specimens were made from it by careful machining and grinding. All of the reported tests results were obtained from samples from this bar (bar No. 1) and one other of similar source (bar No. 2). No complete analysis was obtained but, based on analysis of similar semi-conductor grade material, metallic impurities were under 0.01 pct total. Vacuum-fusion analysis for oxygen showed a value of 0.0018 2 0.0003 pct for the first bar tested and metallographic analysis showed no evidence of a second phase. Bend tests were carried out on an Instron tensile machine using a bend fixture with a 1 -in. span loaded at the center. Supporting and loading bars were 0.250 in. round and the load was applied by downward motion of the pulling crosshead of the machine. Specimen thickness and width were approximately 0.10 in. and % in. respectively. Loading rate was controlled by holding crosshead motion constant at 0.02 ipm. In some cases a smaller specimen was used on a 5/8-in. span with a 0.129-in.-diam loading bar. The entire bend fixture was surrounded by a hinged furnace and all heating was done in air atmosphere. Temperature measurement was made with thermocouples fastened directly to the bend fixture within less than 1 in. from the specimen. Autographic stress-strain curves were recorded during each test, and breaking load, total deflection, and plastic strain could be obtained from these curves. Stress was calculated from the beam formula S = 3PL/2bh2, where P is the load in pounds, L the span in inches, b the specimen width in inches, and h the specimen thickness in inches. This formula is strictly correct only in the elastic range but has been used to calculate a nominal stress for convenience in the plastic range. The stress given is the maximum stress in the specimen. Results The results of the complete series of tests are shown in Table I. The first group of tests (specimens Nos. 1-6) showed the beginning of plastic flow at a test temperature of 900°C, so two additional tests (Nos. 8 and 9) were made at 950°C on small-size specimens from bar No. 2. Specimen No. 8 was tested in the as-machined condition, and No. 9 was heat-treated in hydrogen at 1300°C for 2 hr, cooled to 1200°C and held 1 hr, cooled to 1000°C and held 1 hr, cooled to 900°C and held 1 hr, and finally cooled to a low temperature before removal from the hydrogen. It is apparent that the heat-treatment had a significant effect on yield strength and ductility. In addition, the magnitude of the yield point was conslderably reduced in the heat-treated specimen as is shown m Fig. 1 by tracings of the stress-strain curves. After obtaining a furnace capable of reaching higher temperatures specimens Nos. 10 to 13 were tested at 1100 and 1200°C. Strain rate was increased by up to a factor of 10 to see whether the ductility observed was excessively strain sensitive. Specimen NO. 10, strained at 0.02 ipm and 1100oC, was still bending at a deflection of 0.322 in. when the load rate was increased to 0.2 ipm, resulting in immediate

Jan 1, 1959

By L. D. Woodworth, E. E. McGinley

During the past several years has occurred what, in the light of future events, may aptly be called the rebirth of the acid Bessemer process. The increased attention given to the technical and metallurgical details involved in the production of Bessemer steels has been exceedingly fruitful, and indicates the value of further research and p1ant development. In times like these, when the steelmaking capacity of the country is operating at a maximum rate to supply materials for the national defense program, it behooves the Bessemer operator not only to strive to increase production but also to maintain a high standard of quality. The opportunity is ripe, it seems, to recapture fields of application once considered the birthright of Bessemer steels, but supplanted in recent years by open-hearth grades. This involves cooperation all along the line, from the blast-furnace operator to the metallurgical contact man and salesman. The metallurgist's part in this program involves the study of the many steelmaking variables and the measures necessary to ensure constancy in the finished product. It is equally important that the knowledge gained be disseminated widely to ensure the wise application of Bessemer steels in new fields. The merits of Bessemer steels for certain work are well understood. The combined properties of good weldability, machinabil-ity and stiffness are unique and fully explain the strong entrenchment of Bessemer steels in certain fields; e.g., skelp for small butt-weld conduit, screw steels machined in automatics, and certain tin-plate applications. It is the purpose of this paper to review briefly the physical properties of Bessemer steels as contrasted with those of open-hearth steels, to discuss control measures now employed in the making of Bessemer steel, and to consider the advantages derived from the use of these control measures. Physical Properties oF Bessemer vs. Open-hearth Steels A number of Bessemer blows and open-hearth heats were tested for tensile strength, ductility and impact strength. The steels selected were confined to sections from 3/4 to 1 1/4-in. diameter, inclusive, and the carbon content covered was sufficient to yield parallel ranges in ultimate strength for the comparison. Other factors, such as the extent of deoxidation of the steel and variations in chemistry, were kept as comparable as possible. Machined test pieces of 0.505-in. diameter with an 8-in. gauge length were pulled. The data obtained are shown in Fig. I, ultimate strength being plotted against carbon content. This graph shows that for equivalent carbon content Bessemer steel has on the average 15,000 lb. per sq. in. greater tensile strength and, conversely, for the same tensile strength Bessemer steel requires on the average 0.14 per cent less carbon. The average phosphorus content for the Bessemer steel was 0.090 per cent,

Jan 1, 1941

By E. E. McGinley, L. D. Woodworth

During the past several years has occurred what, in the light of future events, may aptly be called the rebirth of the acid Bessemer process. The increased attention given to the technical and metallurgical details involved in the production of Bessemer steels has been exceedingly fruitful, and indicates the value of further research and p1ant development. In times like these, when the steelmaking capacity of the country is operating at a maximum rate to supply materials for the national defense program, it behooves the Bessemer operator not only to strive to increase production but also to maintain a high standard of quality. The opportunity is ripe, it seems, to recapture fields of application once considered the birthright of Bessemer steels, but supplanted in recent years by open-hearth grades. This involves cooperation all along the line, from the blast-furnace operator to the metallurgical contact man and salesman. The metallurgist's part in this program involves the study of the many steelmaking variables and the measures necessary to ensure constancy in the finished product. It is equally important that the knowledge gained be disseminated widely to ensure the wise application of Bessemer steels in new fields. The merits of Bessemer steels for certain work are well understood. The combined properties of good weldability, machinabil-ity and stiffness are unique and fully explain the strong entrenchment of Bessemer steels in certain fields; e.g., skelp for small butt-weld conduit, screw steels machined in automatics, and certain tin-plate applications. It is the purpose of this paper to review briefly the physical properties of Bessemer steels as contrasted with those of open-hearth steels, to discuss control measures now employed in the making of Bessemer steel, and to consider the advantages derived from the use of these control measures. Physical Properties oF Bessemer vs. Open-hearth Steels A number of Bessemer blows and open-hearth heats were tested for tensile strength, ductility and impact strength. The steels selected were confined to sections from 3/4 to 1 1/4-in. diameter, inclusive, and the carbon content covered was sufficient to yield parallel ranges in ultimate strength for the comparison. Other factors, such as the extent of deoxidation of the steel and variations in chemistry, were kept as comparable as possible. Machined test pieces of 0.505-in. diameter with an 8-in. gauge length were pulled. The data obtained are shown in Fig. I, ultimate strength being plotted against carbon content. This graph shows that for equivalent carbon content Bessemer steel has on the average 15,000 lb. per sq. in. greater tensile strength and, conversely, for the same tensile strength Bessemer steel requires on the average 0.14 per cent less carbon. The average phosphorus content for the Bessemer steel was 0.090 per cent,

Jan 1, 1941