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By R. W. Gould, B. G. LeFevre, A. G. Guy

The resistivity anomaly known as the K state was studied in Ni-Mo alloys containing 10.5 and 14.0 at. pct Mo. Both these alloys exhibit a large K effect which depends on the mechanical and thermal treatment. On the basis of X-ray diffuse scattering studies which were correlated with resistivity measurements, it appears that the K state in dilute Ni-Mo alloys can be associated with changes in the degree of short-range order within the a phase. An interesting phenomenon that has received much attention in recent years is the K state. The K state is marked by anomalous changes in some of the physical properties of certain alloys without the occurrence of observable microscopic structural changes. One of the early pieces of work in this area was by Thomas' who studied alloys of Ni-Cr, Ni-Cu, Ni-Cu-Zn, Fe-A1, Fe-Si, and Ni-A1. Upon annealing specimens which had been previously cold-worked or quenched from an elevated temperature he found an anomalous increase in resistivity over a certain temperature range. He also found that specimens which had been appropriately annealed to develop the K state showed a decrease in resistivity upon subsequent cold working. These effects are opposite to those found in normal alloys. Although the resistivity anomaly has been rather arbitrarily taken as the "definition" of the K state, there are several other interesting effects which accompany the resistivity increase. In Ni-Cr alloys,2, 3 for example, it was found that the hardness increases with increasing resistivity. It was also found that specimens which have been treated to develop the K state can be cold-worked for as much as an 80 pct reduction of area without an increase in the hardness. In Fe-A1 and Fe-Si alloys4 the K state is accompanied by an increase in flow stress and by a lattice contraction. In Ni-A1 alloys,5 specimens which have been treated to develop the K state also show an increase in elastic modulus. In Ag-Pd alloys6 the increased resistivity observed on annealing a cold-worked specimen is accompanied by an increase in the thermoelectric power and an increase in the Hall coefficient. The explanations of the K state phenomena are varied and depend upon the particular alloy in question. Several theories have been advanced to explain the increased conductivity with cold work on the basis of changes in the electronic configuration of the alloy as a result of local lattice distortions.7"9 Most investigators, however, believe that some type of local order in the solid solution, either short-range order (SRO) or clustering, is responsible for this effect. Theories concerning the relationship between ordering and the K state have for the most part been speculative, since there is little direct X-ray evidence that can be correlated with the above property changes. Much of the previous work on the K state was done in the Ni-Cr system where the small difference in the X-ray atomic scattering factors of the components nickel and chromium makes it very difficult to use X-ray diffuse-scattering measurements to determine the role of local order. In the Ni-A1 system, however, Starke et al.10 succeeded in detecting a connection between local order and the K state. It was found that a small but measurable K effect correlated with increasing SRO in the nickel-rich a phase. The manner in which local order might increase the resistivity of K state alloys is not completely clear. Since most of the known K state alloys contain at least one transition element, significance has frequently been attached to the presence of an unfilled d shell. It has been suggested that during the formation of the K state the number of conduction electrons decreases as a result of the transfer of s electrons to the d shell where they are more tightly bound.1'11'12 Koster and Rocholl13 have proposed that SRO can cause an increase in resistivity for alloy systems in which the number and mobility of charge carriers are reduced when the percent solute is increased. According to this hypothesis, the local environment of a given solvent atom changes in the same manner with increasing percent solute as it does with an increasing degree of SRO; hence the change in physical properties should tend in the same direction. In this hypothesis, SRO is considered only in a statistical sense, and the increased resistivity of the K state is attributed to a change in the mean distribution of electrons and holes in the s and d states as a result of SRO. From the work of Chen and Nicholson on Ag-Pd alloys,6 it appears that the K state can occur in systems for which the d shell is completely filled. These investigators explained the increased resistivity by picturing the SRO as small domains of some form of long-range order (LRO). According to ~ibson,'~ the number of effective electrons can be reduced by the creation of a new Brillouin zone boundary near the Fermi surface of an alloy as a result of the changing crystallographic symmetry that accompanies the formation of a superlattice. This idea may be expressed in terms of the superzone concept.15 In the present work the role of local order in the formation of the K state in Ni-Mo alloys was investigated. The principal tools used in this study were X-ray diffuse scattering and electrical resistivity measurements; however, these data were supplemented by electron microscopic and field-ion microscopic data. The purpose of the work was to determine whether or not the K state in Ni-Mo alloys can indeed be attributed to the formation of SRO as has been proposed by previous investigators.

Jan 1, 1969

By Sandford S. Cole, John S. Breitenstein

The recovery of over 80 pct of the vanadium values in titaniferous magnetite from Maclntyre Development,Tahawus, N. Y., was accomplished by an oxidizing roast with Na2O3-NaCI addition. Process description is given for leaching of roasted ore and precipitation of V2O5 and Cr2O8 from leach liquor. THE exploration and development of the Mac-Intyre orebody at Tahawus, N. Y., by the National Lead Co. provided a source of vanadium. Analyses of various composite sections of the drill cores of the MacIntyre orebody were made to establish whether or not the vanadium was constant throughout. Ten drill cores were sampled as 50 ft sections, crushed, and a portion magnetically concentrated. The head and concentrate were analyzed for total iron and vanadium. The results on the concentrates indicated that the vanadium is associated with the magnetite and maintains a close ratio to the iron content. The nominal ratio of 1:25:140 of V: TiO2:Fe was found to exist in the concentrates. Typical value for the vanadium in the magnetite both from laboratory concentration and mill production is 0.4 pct. The recovery of vanadium from the magnetite was investigated in 1942 to 1943. The research program encompassed both laboratory and pilot-plant work on sufficient scale to provide adequate data to establish the feasibility of a full scale plant. The recovery of vanadium from various ores has been reported in the literature and has been the subject of many patents. The literature dealing with recovery from titaniferous ore by roasting is quite limited. Roasting with alkaline sodium chloride, sodium chloride or alkaline earth chlorides, and sodium acid sulphate have been claimed in various processes as effective means.1-8 The reduction of the ore, followed by acid leaching, was another method proposed.'-' "he use of various pyrometallurgical processes for recovery of vanadium in the metal or in the slag has also been extensively investigated, but the results had little application to the problem."-" The separation of vanadium values from subsequent leach liquors and vanadium-bearing solution has been the subject of a considerable number of papers and patents. The most practical is by hydrolysis at a pH of 2 to 3 by acidifying a slightly alkaline solution. Data on solubility of V²O5 and V2O4 in water and in dilute sulphuric acid indicated a solubility of 10 g per liter in water.'" Laboratory Results Magnetite Analysis: Adequate stock of magnetite was provided so that the laboratory and pilot-plant operation was on ore representative of the mill production. The ore was analyzed chemically and examined by petrographic methods to ascertain whether the vanadium was present in combined state or as an interstitial component between grain boundaries. No evidence was obtained which would indicate that the vanadium was in a free state as coulsonite.15 The analysis of the ore was as follows: Fe²O³, 47.4 pct; FeO, 29.1; TiO,, 10.1; V, 0.40; and Cr, 0.2. The screen analysis of the ore on the as-received basis was: -20 +30 mesh, 28.8 pct; —30 +40, 18.9; -40 +50, 9.7; -50 +60, 15.1; -60 4-100, 5.9; -100 + 200, 11.2; -200 +325, 3.7; and -325, 7.2. Roasting Conditions: The prior practice indicated that a chloridizing roast with or without an alkaline salt had been effective on other titaniferous magnetites. On this basis roasts with additions of sodium chloride, sodium carbonate and mixtures thereof were investigated varying the roasting temperature between 800" and 1100°C. Since the ore had shown no segregation or concentration of vanadium, the influence of particle size on the freeing of vanadium by the reagents during roasting was determined. The initial work was on silica trays in an electric resistance furnace with occasional rabbling of the charge. Subsequently, the roasting was carried out in a small Herreshoff furnace to establish the influence of products of combustion on the recovery of the vanadium. The laboratory tests showed that this ore required an alkaline chloridizing roast, in conjunction with a reduction in particle size to less than 200 mesh. When roasted in air at 900 °C with 5 pct NaCl and 10 pct Na2CO³, over 80 pct recovery of the vanadium was attained as a water-soluble salt. The presence of alkaline earth elements gave detrimental effects and care had to be exercised to avoid any contamination of the ore or roast product by such materials. The solubilization of vanadium under the various conditions is given in a series of curves in Figs. 1 to

Jan 1, 1952

Our mission is help ensure our country has an adequate, dependable supply of minerals and mate al to meet its national security and economic needs at acceptable social, environmental, and economi[c] costs. We do this by promoting and encouraging private enterprise in the development of viable and stable mineral industries through the transfer of innovative extraction, processing, recycling, an environmental technologies; our use of cooperative partnerships with industry, academia, an government; our timely, authoritative worldwide mineral intelligence; our advocacy of public policies based on good science and sound economics.

Jan 1, 1994

By R Steinhaus, D M. Frantois-Bongarton, P W. Cleary, G K. Robinson, M D. Sinnott

Multotec Process Equipment and Dominique Frantois-Bongarton have a patent for a mineral sampling device, which they call a æTrue-Belt SamplerÆ. This uses a plough, which is rotated about an axis parallel to a conveyor belt to throw material off the belt. A fixed sample cutter takes a sample from the material thrown off the belt.Discrete element modelling has been used to consider a range of plough designs, plough speeds, positions for the cutter relative to the plough, cutter apertures, cutter designs and frictional properties, prior to the building of a physical prototype. This modelling work will be discussed, both as an illustration of the role of modelling in the development of new materials-handling devices and in order to explain the likely strengths and weaknesses of this new type of sampling device.CITATION:Robinson, G K, Sinnott, M D, Cleary, P W, Steinhaus, R and Frantois-Bongarton, D M, 2012. Modelling of a ætrue-belt samplerÆ - A new device for sampling from a conveyor belt, in Proceedings Sampling 2012 , pp 33-40 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By Henry M. Howe

THIS meeting was held at the home of the Institute in the United Engineering Society Building, 29. West 39th St., New York, N. Y., Feb. 18 to 21, 1908. The first session, held in the large auditorium Tuesday evening, Feb. 18, was called to order at 8 p.m. by Prof. Henry M. Howe, Past-President of the Institute, who welcomed the members and guests in a few cordial and well-chosen remarks. The following papers, accompanied by lantern-illustrations, were presented in oral abstract by their authors Swedenborg and Humboldt, by R. W. Raymond, New York, N. Y. Electric Power in Steel Mills, by David B. Rushmore and Karl A. Pauly, Syracuse, N. Y. At the close of the session, an informal reception in the offices of the Institute was tendered to members and guests. The second session, held in Assembly Room No. 1 in the same building, Wednesday, Feb. 19, was called to order at 10 a.m. by Prof. Robert H. Richards, Past-President of the Institute. Before proceeding with the papers on iron and steel, which were scheduled for presentation at this session, Mr. F. E. Junge, a representative of the gas-engine and electric motor industry of Berlin, Germany, gave a short oral discussion of the paper by Mr. Rushmore and Mr. Pauly, Electric Power in Steel Mills. Printed copies of the paper, Uniform Nomenclature of Iron and Steel, were distributed among the members and guests present, and the request was made for a later discussion of this important subject by letter. This paper constitutes the Report of Committee No. 24, of the International Association for Testing Materials, which was presented at the Brussels Congress in 1906. The following paper was presented in oral abstract by the author

Mar 1, 1908

By Ivan César Lopes Diniz, César Romero Afonso Goulart Júnior

Mandrels are tools applied to manufacturing seamless tubes. In VSB plants (Vallourec Soluções Tubulares do Brasil), it is used in two mills. Mandrel and PQF Mills. This is an expensive tool due its alloy (hot work tool steel – AISI H13) and lengh (between 12 meters and 22,5 meters). An opportunity to apply mandrels from PQF in Mandrel Mill has been identified. However, mechanical properties of PQF mandrels must be improved. This work presents the heat treatment process of Quenching and Tempering developed internally at VSB to improve PQF mandrel properties aiming to achieve Mandrel Mill requirements. Hardness and metallography tests were performed before and after some steps of the heat treatment to characterize and validate the process.

Oct 5, 2019

By W. M. Wojcik, R. F. Kowal

Oxygen and sulfur distributions in commercial, 5-ton ingots of killed, medium carbon steel are described. Oxygen distribution is found to vary with deoxidation practice. Irregular distribution of oxygen within ingots makes necessary special precautions in sampling of rolled products for analysis of oxygen. Oxygen distribution is discussed in terms of recently published solidification concepts which had been successfully applied to simpler cases of segregation. These concepts have been found inadequate to explain observed oxygen distributions. Convective movements of the liquid metal, as determined by tracer elements, are shown to be capable of accounting for the observed distributions of oxygen. IN an effort to explore the origin of surface and subsurface imperfections in pierced steel products, a study of oxygen and sulfur segregation was made on ingots cast in open-top and hot-top molds. The results of our previous investigations1"3 have indicated the importance of the location and amount of oxide inclusions in an ingot. Inclusions close to the surface of the ingot have been found to contribute greatly to the formation of imperfections in the surface of finished products. This study of the effects of deoxidation and casting practice on segregation and the resulting oxygen distribution in ingots was initiated to determine the parameters controlling the location of inclusions in an ingot. Segregation of solute elements during solidification of low-melting binary alloys has been studied in the past.1, 5 Formation and growth of inclusions in iron melts have been studied under specific conditions."- In spite of these and other recent studies,10-12 segregation during solidification of commercial, killed steel ingots is not well understood. Consideration of solidification rates, of segregation during solidification of the chill, dendritic, and central zones, and of material balances for the segregated elements has indicated that a simplified theoretical solidification model is not adequate. However, the observed high oxygen contents in localized volumes of the dendritic zone can be rationalized if additional effects of convection currents in the ingots, precipitation, and rapid growth of new phases are considered. EXPERIMENTAL PROCEDURE Steelmaking and Processing. A group of nine killed. medium carbon steel heats having compositions listed in Table I have been studied. The deoxidation and mold practices used were varied to give a wide range of steel oxygen contents. The amounts of aluminum added to the ladle and the ingot casting practices (hot top and open top) were the main variables. The steel was made by a duplex practice in 160-ton tilting basic open-hearth furnaces. All nine heats were top-cast into 24 by 24 in. big end down, fluted molds, to a height between 60 and 76 in., using both open tops and exothermic hot tops. The deoxidation practice and the tapping and teeming details for each heat and ingot studied are given in Tables II and III, respectively. Hot-top practice is indicated by the letter H following the heat designation. Furnace and ladle temperatures were measured by standard disposable-tip, Pt/10 pet PtRh thermocouples. Teeming-stream temperatures were obtained as described by Samways et al.,13 by immersing a Pt/10 pet PtRh thermocouple, covered by a silica sheath, into the teeming stream under the nozzle. The output of this thermocouple was recorded with Leeds & Northrup Speedomax potentiometer. Calibration of the latter thermocouples was based on the freezing point of a pure iron/oxygen alloy (2795°F). The accumulated errors of measurements were within ±10°F. The thermocouple measurements were supplemented in this investigation by continuous recording of a ratioing, two-color pyrometer (Shawmeter), protected from smoke by a blast of clean air within the sighting tube, and calibrated to read with better than ±10°F accuracy. Following teeming of three heats, P, R, and T, tracer elements were added to the steel in the molds to obtain a record of the progress of solidification. As soon as the teeming stream was shut off, a 0.010-in.-thick steel can containing a mixture of crushed standard ferro-titanium and ferro-vanadium (0.05 pet of each alloy element) was plunged into the middle of the steel pool to a depth of 6 in. In about 30 sec no indication of the can or its contents remained. The surface of the open-top ingots solidified in 20 to 30 sec. A study of liquid metal movement and the precipitation of oxides was facilitated materially by use of the tracer technique as titanium has a low distribution coefficient between solid and liquid steel while vanadium has a high distribution coefficient.

Jan 1, 1965

By W. R. Sharp

The ability to target, delineate, excavate, and produce local resources is essential to the establishment of man's long-term presence in space. Many procedures and equipment utilized to mine resources here on Earth may be directly applicable on the lunar surface, while others may need extensive redefinition and development. This paper compares, for a lunar base, the alternative of burrowing into and below the lunar surface with that of surface mining. A conceptual underground mechanical excavator is presented.

Jan 1, 1991

By Frederic P. Dewey

The Bureau of the Mint of the United States Treasury maintains 13 ofEces for the purchase of gold-bullion, and this paper describes an investigation to establish the reasonable differences in the assay-results at the various institutions which may be commercially allowable in the settlements between them. Beginning with the comparative assay of proof-gold at the Philadelphia mint and the Utrecht mint, which shows 0.00002 as the closest agreement now possible, nine tables of comparative results, taken from the regular work of the service, are given..These tables begin with very fine gold, produced in an electrolytic refinery, showing close agreement in the assay-results, and follow through decreasing gold fineness and increasing amounts and complexity of base metals to very impure and complex bars produced at cyanide-mills, some of which give widely-varying results. Next is given a series of results on samples, prepared and sent out to various laboratories in the service, to test the influence of different metals and various combinations upon the agreement of the assay-results ; 11 samples were sent out and each one was assayed from 44 to 71 times, making a total of 623 assays. To these ire added 107 assays of identical samples of coin-gold. On a previous occasion,' I have endeavored to show the degree of accuracy that may be expected in the ordinary everyday analysis of various materials, and on another occasion,2

Jan 1, 1910

By Charles F. Hickey, Eric B. Kula

Thermomechanical treatments applied to the maraging steels include a) cold working in the austenitic condition at 650°F, followed by transformation to martensite and aging, b) cold working in the murtensitic condition and aging, and c) cold working in the aged condition with and without subsequent reaging. The strength increases in these steels are very small compared to the increases observed in conventional carbon and alloy steels. The changes that are observed are compatible with the strengthening mechanisms operative during thermomechanical treatment of conventional steels, however. Differences are caused by the absence of a carbide precipitate and the low work-hardening rate in both the solution-treated and the aged conditions. ThE 18 pct Ni maraging steels represent a class of steels which are finding great interest for high-strength applications.1~2 They are essentially carbon-free, and contain 7 to 9 pct Co, 3 to 5 pct Mo, and 0.2 to 0.8 pct Ti. Although austenitic at elevated temperatures, they can be air-cooled to room temperature to form a martensite, which because of the absence of carbon is relatively soft. On subsequent reheating age hardening occurs and strength levels of 250 to 300 ksi yield strength can be attained. These steels appear to be particularly suitable for studying the response to various thermome-chanical treatments for additional reasons other than the obvious one of attempting to improve their already attractive properties. Thermomechanical treatments can be defined as treatments whereby plastic deformation, generally below the recrystal-lization temperature, is introduced into the heat-treatment cycle of a steel in order to improve the properties. With an absence of intermediate transformation products on air cooling the maraging steels have good hardenability and hence can readily be cold-worked in the austenitic condition prior to transformation to martensite. Further, they can be worked in the martensitic condition prior to aging, and even can be deformed in the fully aged condition. Finally, it is of interest to compare their re- sponse to that of the more conventional alloy and carbon steels, where the role of carbides is important in the strength increase by thermomechani-cal treatments. The thermomechanical treatment of conventional steels has been the subject of a recent review.' I) MATERIALS AND PROCEDURE The steel used in this investigation was a commercially produced vacuum-melt heat, which had been rolled to 0.090 in. and mill-annealed. The composition of the alloy was as follows: 0.02 C, 0.08 Mn, 0.10 Si, 0.009 P, 0.009 S, 18.96 Ni, 7.34 Co, 5.04 Mo, 0.29 Ti, 0.05 Al, 0.004 B, 0.01 Zr, and 0.05 Ca. Unless otherwise stated the heat treatments used were the standai-d solution treatment at 1500°F for 1 hr, air cool, followed by a 900°F, 3 hr age. In this condition, the material exhibited 232 ksi yield strength and 239 ksi tensile strength. Mechanical properties were determined by Vicker's hardness measurement (20 kg) and by tensile tests on standard 1/2-in.-wide, 2-in.-gage-length sheet tensile specimens. Notch tensile tests were run using the 1-in.-wide NASA type, edge-notched specimen.4 Fracture-toughness determinations were made on 3-in.-wide, center-notched, fatigue-cracked specimens, following the recommendations of the ASTM Committee on Fracture-Toughness Testing.4 An electric-potential technique was used for measuring the crack size at the onset of rapid crack propagation5 which is necessary for calculations of Kc, the critical stress-intensity factor under plane-stress conditions. The critical stress-intensity factor under plane-strain conditions KI, was also calculated, using the stress at which the first observable crack growth occurred. 11) RESULTS A) Cold-Worked in the Austenitic Condition. The reported M, temperature for the 18 pct Ni maraging steel is about 310°F.1 Therefore, a temperature of 650°F was selected as suitable for rolling in the austenitic condition. Specimens were solution-treated at 1500°F for 1 hr, air-cooled to 650°F, and rolled varying percentages from 0 to 60 pct, at 20 pct reduction per pass. Tensile and hardness properties after aging at 900°F for 3 hr are shown in Fig. 1. The tensile strength increases from 253 to 271 ksi and the yield strength from 247 to 265 ksi as a result of a reduc-

Jan 1, 1964

By W. H. Eddy

The Bureau of Mines used several laboratory batch flotation schemes combined with magnetic separation to investigate the feasibility of recovering potash feldspar and glass sands from molybdenite tailings. Four molybdenite tailings or prospective tailings were used as test samples. Feldspar concentrates containing from 10.7 pct to 12.0 pct K2O were recovered from three of the four samples. The alkali content of the fourth sample met the grade for a mixed feldspar. All the feldspar concentrates contained iron in excess of the 0.10-pct-Fe203 specification for most uses. Electron-beam microprobe examination of the feldspar concentrates showed the presence of an iron-bearing potash feldspar in quantities that were excessive with respect to most iron specifications. However, a high-quality glass sand was produced from all of the samples.

Jan 1, 1980

Pennsylvania has been a leader in the pageant of industrial America because of her natural mineral re- sources, geographical location, and the ingenuity and industry of her citizens. Brick and other clay products were manufactured in Philadelphia in William Penn's time. Ores of iron, zinc, lead, and copper were mined and smelted in eastern Pennsylvania long before the Revolution. Coal was mined on a commercial basis in the anthracite region as early as 1820 and in the bituminous fields in 1830. The first canals and railroads were constructed to transport minerals and mineral products. Oil was struck at Titusville in 1859. A significant event occurred in 1855-the establishment of the Farmers' High School-Pennsylvania's first attempt to provide higher education for its youth. The Farmers' High School included instruction in geology, mineralogy, and assaying. In 1859 the laws of Pennsylvania transferred to the School the state geological and mineralogical collections formerly located in Harrisburg. Well-informed people are familiar with the effects of the Land-Grant Act of 1862. With inspiring words it established state institutions of higher learning where "the leading object shall be, without excluding other scientific and classical studies . . . to teach such branches of learning as are related to agriculture and the mechanic arts . . . in order to promote the liberal and practical education of the industrial classes in the sev-

Jan 1, 1950

By Michael J. Klishis

Accident rates continue to show that underground mining jobs areamong the most hazardous occupations in the United States and roof bolter operators continue to have one of the highest accident incident rates (MSHA, 1991) despite efforts by labor, government, and industry to reduce and eliminate work-related hazards. In the last two decades we have seen technical innovations such as the ATRS, and there has been an increased emphasis on hazard awareness through programs such as MSHA's REAP, but bolter operators continue to be injured and killed. Researchers at West Virginia University examined risk in the roof bolter's job and developed new approaches to accident and injury prevention. The study concentrated on the workers' job performance, machinery and the work environment to identify miner's risk and hazard exposure while bolting.

Jan 1, 1993

By W. A. Binsacca

The concentrator treats sulfide ore containing lead, copper, zinc, gold and silver, at the rate of 850 tons per 24 hr., and produces lead, copper, zinc and iron concentrates by selective flotation methods. The ore occurs below the oxidized zone along a main fracture, the wall rock of which is either greywacke or calcareous shale. The predominating sulfide minerals are galena, sphalerite, pyrite and chalcopyrite; the others are quartz and calcite. In minor amounts, arsenopyrite, pyrrhotite and hematite occur, and such secondary minerals as smithsonite, chalcocite, covellite, bornite, cerussite and anglesite are detected in the ore, the last two named occurring principally as surface alterations of the galena. The ore is hauled from the mine bins in 10-ton cars which pass over the track scales before entering the car dumper ahead of the crusher plant.' A conveyor belt delivers the crushed ore to the sulfide bin, which has a capacity of 2800 tons. The primary grinding unit consists of two 6 by 12-ft. Marcy rod mills operating in parallel and in open circuit, each taking 425 tons per day. One rod mill discharges into an 8 by 25-ft. Dorr classifier with a 12-ft. bowl and the other into a 6 by 25-ft. Dorr duplex classifier. These classifiers are arranged so that each unit rakes the sands into a 6 by 14-ft. Traylor ball mill, which discharges to the bowl classifier only. The duplex classifier therefore operates in open circuit and the bowl classifier in closed circuit, the overflow of both classifiers furnishing the feed for the flotation section. Other groupings have been tried, but this has been found the most satisfactory. The Marcy mills are driven by 150-hp. slip-ring induction motors with speed reducers to give 17 r.p.m. The Traylor mill operates at a speed of 24 r.p.m. and is driven by a 200-hp. slip-ring induction motor, direct connected to pinion and gear. The bowl classifier operates at a speed of 22 r.p.m., with the bowl rake making 4.5 r.p.m. and the duplex classifier at 31 r.p.m. High-carbon steel rods of Mexican manufacture, 12 ft. long by 3-in. diameter, are used in the Marcy mills, with a resulting consumption of 1.52 Ib. per ton ore. The Traylor mill is fed 3-in. cast-iron balls cast in

Jan 1, 1935

By K. E. Yassin, A. Yehia, M. Amar

Phosphate fines (size ≤ 45 μm), from the Red Sea Region, Egypt, were subjected to beneficiation process to recover the phosphorite grains from such fines. The sample is characterized by low P2O5 content (18.78%) associated with gangue minerals such as silica (22.77% SiO2) and carbonate (2.01% MgO) indicating its low grade. Phosphate pre-concentrate was prepared by gravity separation, using Falcon, where 63.37% of the phosphate, with 24.94% P2O5, 1.46% MgO, and 10.54% SiO2, was firstly recovered reducing the mass flow to the subsequent beneficiation process. However, the gravity tailing was the feed for the reverse phosphate flotation using bench scale column flotation where oleic acid was used as a carbonate gangue collector and amylase enzyme as a phosphate depressant. Under the appropriate flotation conditions (0.1% amylase, 5·10−4 mol/dm3 oleic acid, and temp. 30 °C), phospho-concentrate assaying 0.61% MgO, 13.14% SiO2, and 27.85% P2O5 with a P2O5 recovery of 55.45%, was finally obtained without the use of expensive depressants, e.g., phosphoric acid or sodium silicate. A tentative flow sheet for the whole process was postulated.

By F. M. Goodwin, John Campbell, G. W. Jones

"INTRODUCTION In previous reports 5 results were given of a manhole investigation carried out over a period from June 1929 to July 193C in cooperation with the Edison Electric Illuminating Co. of Boston. Mass., and during 1931 in cooperation with the Edison Electric Illuminating Co. of Boston and the Boston Consolidated Gas Co., to determine the general hazards of combustible gases and vapors in manholes and other underground openings owned by the Edison Electric Illuminating Co. and to develop methods of eliminating these hazards. These investigations have demonstrated that the detection, control, and elimination of combustible hazards in manholes can best be obtained by a close cooperation of the interested parties through a systematic and continuous inspection of manholes, under proper supervision.The investigation carried out during 1932 has been along lines similar to those conducted during 1929, 1930, and 1931 test crew consisting of two men, one an employee of the Consolidated Gas Co. and the other an employee of the Edison Electric Illuminating Co., was continuously employed during the year in the testing of gases in manholes served by the Edison system. The test crew was under the direct supervision of John Campbell, superintendent of the special service department of the Edison Electric Illuminating Co., and F. M. Goodwin, vice president of the Consolidated Gas Co.As in the previous investigations, all tests were numbered. The test-data sheets, on which the information regarding the tests was recorded, were prepared in triplicate, ono copy going to the Edison Co., one to the gas company, and the third to the Bureau of Mines at Pittsburgh, Pa. These test-data sheets were then filed (1) according to the town, (2) the street location, and (3) the manhole number; in this way a complete record of each manhole tested was immediately available. A typical test-data sheet was given in the 1931 report. These data sheets were found to entirely satisfactory and no changes were made during the 1932 investigation. The procedure of sampling manhole atmospheres, shipment of the samples to Pittsburgh, and method of analysis has been the same as that described in the 1931 report and need not be repeated here. Likewise, there has been no change in the method of calculation of explosibility of the samples analyzed or the use of charcoal filter tests given in appendix A."

Jun 1, 1933

By E. Chin

The countries of Asia and the Pacific, with their large mineral resource base, are significant suppliers of a wide variety of minerals to both regional and world markets. Australia, China, and India dominate the commercial mineral exploitation in the region. Australia has known reserves of major minerals, which are adequate for both domestic demand, and for exports, and is a significant producer of bauxite; copper; diamond; gold; iron ore; lead; manganese; mineral sands (titaniferrous minerals, monazite, and zircon); nickel; salt; silver; tin; uranium; and zinc. China is the world leader in proven reserves of antimony, barite, ilmenite (titanium), magnesite (magnesium), molybdenum, rare earths, and tungsten. China also has large resources of low-grade iron ore and significant resources of other mineral commodities, such as coal, based on its production and export capabilities. India has significant resources of bauxite, barite, graphite, iron ore, and mineral sands.

Jan 1, 1995

By H. C. Ko

The Bureau of Mines maintains an active program in thermochemistry to provide thermodynamic data for the advancement of mineral science and technology. As part of this effort, the standard enthalpy of formation at 298.15 K, ?Hf°, for 2CdO-CdSO4 was determined by HCI acid solution calorimetry to be -345.69 ±0.61 kcal/mol.

Jan 1, 1983

By Mark J. Klein

An internal-friction profile induced by nitrogen in Cr-35 at. pet Re was studied as a function of nitrogen concentration and heat treatment. From these studies, the solubility of nitrogen in this alloy was deduced. The equilibrium solubility of nitrogen in chromium does not appear to be substantially changed by the addition of 35 at. pet Re to chromium. However the precipitation kinetics of nitrogen from solution are significantly decreased. IT has been found that rhenium has a beneficial effect on the low-temperature ductility of Group VI-A metals. As part of a study to investigate the mechanism of this increased ductility, it was of interest to compare the concentration of interstitials retained in solution in one of these ductile bee alloys with the concentration retained in solution in its base metal. In this regard, a study of the solubility of nitrogen in ductile Cr-35 at. pet Re was selected for this phase of the investigation because the solubility of nitrogen in the base metal, chromium, has been determined over a fairly large temperature span.1-3 In addition, nitrogen is known to have an embrittling effect on chromium,4 but does not appear to have a comparable embrittling effect on Cr-35 at. pet Re.5 The experimental method selected for this study was the measurement of internal friction. This technique allows interstitial-concentration measurements to be made in bee metals that are sensitive to small changes in the concentration of a particular interstitial, even when other interstitials are present. When subjected to a cyclic stress, interstitial atoms in solid solution give rise to an internal-friction peak whose origin is the stress-induced ordering of interstitials into preferred lat- tice sites. These internal-friction peaks signify a dissipation of elastic energy which is greatest when the period of oscillation is comparable with the relaxation time for the attainment of an equilibrium interstitial distribution. For dilute interstitial binary alloys, the height of the internal-friction peak is proportional to the concentration of interstitial atoms in solid solutions. snoek8 has shown that the internal friction, Q-1, may be expressed by the equation where A is the relaxation strength, ? is the angular frequency, and 7 is the relaxation time. The relaxation strength, A, is proportional to the concentration of interstitials taking part in the relaxation if no interaction occurs between solute atoms. Thus values of peak height, which can be determined as a function of temperature, give a measure of the relative concentration of interstitial atoms in solution at various temperatures. If equilibrium has been attained, the peak heights will be proportional to the interstitial solubilities. The constant that relates A to the interstitial concentration can be determined experimentally from peak-height measurements as a function of concentration for specimens of constant crystallographic orientation. When this has been done, Q-1 measurements can be used to determine solubilities according to the equation C - KQ-1 where C is the soluble interstitial concentration and K is a constant that can be experimentally determined. It is possible, however, that lattice imperfections may bind interstitials to certain lattice sites. Internal friction does not measure these interstitial~, but does measure interstitials which are free to move in the normal lattice sites when subjected to an applied oscillating stress. On alloying the pure metal with a substitutional

Jan 1, 1965

By E. Maxwell, C. J. Bechtoldt, H. C. Vacher

IN the course of an investigation of the properties of metals at low temperature there was occasion to determine the constitution of four iridium-osmium alloys. There is very little information in the literature1 on the constitution of synthetic Ir-0s alloys. Zvyagintzev' s has made a comprehensive study of different natural Ir-0s alloys and concludes that alloys containing more than 32 pct 0s have the close-packed hexagonal structure of osmium, whereas those containing less than 32 pct 0s have the face-centered cubic structure of iridium. The alloys studied in this work were prepared by the American Platinum Works, Newark, N. J., and were received in the form of fragments approximately 1.5 mm average diameter. The fragments had been obtained by crushing ingots made by fusing charges of iridium and osmium under an arc and air cooling. The ingots were not given a homogenizing heat treatment. Sample fragments Table I. Results of X-Roy Diffraction and Microscopic Examinations Phases Present as Determined by X-ray Diffraction Osmium Alloy Close- Iridium Face- Packed Centered Osmium, Iridium, Hexagonal Cubic Mlcro- WtPot Wt Pct Structure Structure scope 0 99.9 None Present 1 23.6 76.4 None Present 1 38.7 61.3 Present Present 2 59.4 40.6 Present Present 2 79.0 21.0 Present Not detected 2 99.9 0 Present None 1 Note: Chemical analyses of the iridium, osmium, and alloys were furnished by the American Platinum Works. of the iridium and osmium used in making the alloys also were included. Several fragments of each metal and alloy were examined microscopically and by X-ray diffraction. For the X-ray method the fragments were crushed further to pass a 270-mesh screen, then sealed in evacuated fused-silica tubes, heated to 1100°C for 18 hr, and allowed to cool in the furnace. Powder X-ray diffraction patterns were obtained from the annealed fragments by means of a Norelco camera having a diameter of 114 mm, and unfiltered cobaIt radiation. For the microscopic examination several fragments in the as-received condition were mounted in Melmac, (American Cyanamid Co.) and ground using the conventional series of abrasive papers. The polishing was done with 0-2 diamond abrasive on a Microcloth (Buehler Ltd.) lap, wet with xylene. After polishing, the surface was etched electrolytically in a 10 pct solution of chromic acid or in a 10 pct solution of potassium cyanide. Both reagents attacked the osmium-rich constituent, whereas the iridium constituent was attacked slightly by the chromic acid reagent and not noticeably by the potassium cyanide reagent. The results of the X-ray diffraction and microscopic examinations are summarized in Table I. Fig. 1 shows the microstructure of a 21 pct Ir-79 pct 0s alloy. The results indicate an appreciable solid-solu-bility range of osmium in iridium as was reported by Zvyagintzev.' The solid-solubility range of iridium in osmium is more restricted, apparently less than 21 pct Ir. This implies a large range of composition in which two phases can coexist that was not reported by Zvyagintzev.

Jan 1, 1955