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By E. Morrice

This report of the Federal Bureau of Mines presents a laboratory procedure, with the requisite equipment, for electrowinning ingot (liquid) cerium metal from a fused-fluoride bath, the metal purity being about 99.9 percent. Physicochemical studies, including bath properties and electrochemistry, are included, with a speculative model of the mechanisms involved. An historical review of the methods used for electrowinning misch metals and yttrim-group metals, as well as individual rare-earth metals, is presented. The electrolytic preparation of metal from fused salt and nonaqueous media is summarized, along with the unsuccessful attempts at depositing the metals from aqueous solutions.

Jan 1, 1961

By K. C. Dean

The combination of flotation and chemical processing methods presented in this report of the Bureau of Mines enabled treatment of typical low-grade ferberite ores from the Boulder County, Colo. area, to produce specification-grade synthetic scheelite. The overall recovery from ore to synthetic scheelite was 87 percent, based on a flotation recovery of 93 percent and a similar recovery in chemical processing. Preliminary mineral dressing studies revealed that the physical and mineralogical nature of typical ferberite ores precluded high recovery of tungsten in plus 60-percent-W03-grade products by these methods. Therefore, the flotation research was focused on attaining plus 90-percent recovery in a concentrate containing 10 percent W03. Detailed studies were made (1) to establish optimum grinding conditions for obtaining adequate mineral liberation, (2) to develop collecting and modifying reagent combinations that would enable controllable selective flotation, and (3) to define the influence of different pulp solids, temperature, pH, and time for conditioning and for the rougher and cleaner flotation stages.

Jan 1, 1961

By A. Adams

The quality of hafnium metal produced by the Kroll process depends upon the purity of the hafnium tetrachloride. This investigation of methods for purification of hafnium tetrachloride was undertaken to aid in producing a higher purity hafnium metal than is currently produced by the Kroll process, The quantities of metallic impurities in hafnium metal were decreased by contact with molten alkali-metal chloride salt. Contact was achieved by a semicontinuous process of bubbling gaseous hafnium tetrachloride through a molten salt bath or by a batch process, first fusing the tetrachloride with a combination of alkali chlorides and then heating the mixture to sublime the hafnium tetrachloride. Low-melting mixtures of sodium, potassium, and lithium chlorides were used to purify hafnium tetrachloride. About 30 percent of the initial hafnium tetrachloride was trapped during purification with alkali- metal chloride salts. The 95-percent confidence limits (6)4 for the amount of oxygen decrease 60 and 34.3 parts per million when the batch purification is combined with a reduction so that both take place in the same equipment,

Jan 1, 1961

By J. H. Field

Synthesis of hydrocarbons by the Fischer-Tropsch reaction in a hot-gas- recycle system was demonstrated to be technically feasible. This project was undertaken, by the Bureau of Mines, to determine if the system was operable and to ascertain the optimum conditions for the production of gasoline. Carbon steel turnings packed with a void volume from 88 to 90 pct. were satisfactory catalysts, but steel catalysts with greater void volume, either turnings or steel wool, were not as active. Good temperature control with a pressure drop of less than 0.5 pounds per square inch (p.s,i,) per foot of catalyst bed of turnings was obtained by operating with a recycle to fresh feed ratio of 20 and by splitting the total gas flaw and injecting portions into the reactor at different entry ports.

Jan 1, 1961

By M. D. Carver

This investigation was undertaken by the Bureau of Nines to determine the effects of impurity levels on the mechanical properties of columbium at low temperatures. High-purity, electron-bombardment-melted columbium was purchased and used as a basis material. Variations in impurity levels were obtained by arc-melting charges containing definite amounts of added impurities. Tensile tests were conducted at low temperatures. Results showed the almost pure basis metal to be ductile at minus 194° C., the lower limit of the range used, Ductility of less pure columbium appeared to depend on interstitial element content. The ductile-to-brittle transition temperature appeared to be raised by increasing carbon content in the range of 50 to 730 parts per million, nitrogen content in the range of 50 to 200 parts per million, or total interstitial element content in the range of 240 to 1,380 parts per million. Some evidence was obtained indicating that decreasing cold work also raised the transition temperature, but recrystallization appeared to have no effect on it. Variations in interstitial element levels appeared to have little or no effect on ultimate strength of columbim in the range of room temperature to minus 194° C, Physical metallurgy studies of massive arc-melted and electron-bombardment- melted columbium were included in the columbium-tantalum research work assigned to the Albany Metallurgy Research Center in fiscal year 1959.

Jan 1, 1961

By K. E. Tame

The Bureau of Mines is studying possible modifications in conventional uranium ore-processing steps to confine and permit controlled disposal of radioactive wastes. Surveys of Ra226 contamination of liquid wastes from uranium mills indicated that the Vanadium Corporation of America plant at Durango, Colo., had one of the more urgent problems. A possible procedure for minimizing the waste disposal problem was to reuse the waste solution in the mill--in effect, erasing the need for disposal of liquid waste. In examining this possibility, interlocked bench-scale leaching and solvent extraction tests simulating the Durango flowsheet were made. The simulated reuse of barren raffinate for leaching and washing was carried through three separate campaigns of 9, 12, and 35 cycles each.

Jan 1, 1961

By Richard Havens

A flotation procedure was devised by the Federal Bureau of Mines for beneficiating Mount Wheeler, Nev., beryllium ores that contain the beryllium minerals bertrandite and phenacite in a complex association with calcite, fluorspar, mica, quartz, and other accessory minerals, The method also has proven to be effective in trials on ore from the Lake George, Colo., area. Samples used in most of the research ranged from 0.49 to 0.73 percent BeO. Beryllium mineralization varied from two-thirds bertrandite to all phenacite. An unusually high grade sample containing 5 percent BeO as phenacite was floated on a batch basis to prepare concentrate for utilization studies. The beryllium minerals were floated from undeslimed pulps at natural pH using sodium fluoride and sodium hexametaphosphate (HMP), as modifiers, and a fatty acid-fuel oil combination as the collector. Key factors were the use of a minimum of about 4 pounds of sodium fluoride and between 2 and 4 pounds of HMP per ton of ore. Efficacy of the HMP was related to the grind, mineralogical composition, corollary reagents, and type and time of conditioning. Addition of the fluoride, HMP, and collector in that order, followed by appropriate conditioning after each addition, was essential for satisfactory flotation.

Jan 1, 1961

By R. J. Leary

Iron and steel scrap has accounted for 45 to 50 percent of the metallics used by the steel industry. In an electric furnace which utilizes a 100-percent cold charge consisting of about 99 percent scrap and 1 percent pig iron, sensible heat from molten pig iron is not present as it is when hot metal is charged to open hearths and converters. A study of means for more efficient utilization of iron and steel scrap in steelmaking indicated that the time and fuel requirements to melt scrap were important cost factors, particularly in arc-furnace steelmaking. A process to preheat scrap economically prior to charging into the arc furnace has been developed, utilizing efficiently the heat from combustion of fossil fuels as a substitute for electric-arc heating in the initial stage of arc-furnace steelmaking. Scrap is loaded into a portable vertical cylindrical furnace body that is open at the top and has a perforated dropout door at the bottom. In the heating operation, the furnace body containing scrap is placed upon a hollow base connected to a flue, and then the burner and combustion-chamber unit is lowered on top of the furnace body. The stream of hot-combustion products flows down through the bed of scrap imparting heat to it, and the cooled gases exhaust through the flue. After the heating operation the furnace body containing hot scrap is transported to the arc furnace for charging. Thus, the furnace body serves as a charging bucket for top-charged arc furnaces, enabling this preheating process to be integrated into existing material-handling patterns in many arc-furnace plants.

Jan 1, 1961

By J. M. Kuchta

Concentrated hydrogen peroxide (H202) is a highly reactive oxidizing agent that liberates heat when it decomposes. The heat liberated may be sufficient to ignite combustibles with which the peroxide comes in contact. For this reason, concentrated hydrogen peroxide should be handled only by personnel familiar with its many unique properties.6 Hydrogen peroxide is used as a bleaching agent in the manufacture of textiles; this is its major single use in the United States. It is also employed as a reagent in chemical synthesis, as a source of free radicals to start polymerization, as a foaming agent in the manufacture of porous substances, and for its effect on biological processes. Moreover, highly concentrated hydrogen peroxide is a compact source of energy that can be utilized both as a monopropellant and as the oxidizer in a bipropellant system, During World War II, large quantities of highly concentrated hydro- gen peroxide were used as propellants, particularly in Germany. Since then, production of the peroxide has increased rapidly; in the United States alone it has more than doubled since 1950.7 Because of its widespread use, increasing interest has been shown in the hazards of handling the high- strength peroxide.

Jan 1, 1961

By Bernard Porter

The solubility of UO2 was determined at 1,250° C. in ternary melts of UF4 and BaF2 with CaF2, LiF, and SrF2. The solubility of Ce02 was measured at 800° and 850° C. in a solution of CeF3, BaF2, and LiF. The amount of La203 which dissolves at 950° C. in a binary mixture of LiF and LaF3 and a ternary of LiF, LaF3, and BaF2 was also measured. In each case, the amount of soluble oxide was mound to be less than 5 weight-percent. A procedure was developed for filtering fused, oxide-saturated fluoride melts in order to obtain a representative sample for chemical analysis. The oxide content of the samples was determined by an inert-gas fusion procedure.

Jan 1, 1961

By T. T. Campbell

This report traces the development of techniques for the preparation of high-purity rare-earth metals. Rare-earth metals, excepting samarium, europium, and ytterbium, were prepared by converting their oxides to anhydrous chlorides or fluorides and reducing the rare-earth halides with active metals such as lithium or calcium. High-purity, anhydrous rare-earth chlorides were prepared by dissolving the rare-earth oxides in hydrochloric acid to form hydrated chlorides and by subsequently dehydrating the hydrated salts in the presence of ammonium chloride at temperatures ranging from 70° to 360° C. while under reduced pressure (50 microns to 1 inch Hg). The chlorides were also prepared by direct chlorination of rare-earth oxide-carbon mixtures. Reaction efficiencies in excess of 95 percent were obtained by either method; however, purer chlorides were prepared by the aqueous ammonium chloride conversion method. Purification of yttrium chloride by high-temperature vacuum distillation proved to be an effective method of separating, oxygen-bearing compounds from the chloride. Yttrium metal prepared from purified chloride contained significantly smaller amounts of oxygen (990 p.p.m. oxygen in yttrium metal prepared from raw chloride and 200 p.p.m. in that prepared from distilled chloride).

Jan 1, 1961

By Robert H. Merrill

Measurement of the deformation of a borehole in rock subjected to a change in applied stress can be used to calculate the magnitude and direction of the applied stress, provided a satisfactory deformation-applied stress relationship exists , In this investigation by the Bureau of Mines the deformation of a bore- hole in a rock model subjected to a known applied stress was compared with the theoretical deformation of a hole in an elastic, isotropic plate and was found to be in good agreement. Hence, this relationship can be used to calculate the applied stress on a borehole from borehole deformation measurements.

Jan 1, 1961

By Leonard Obert

Subsidence to surface occurs in a large proportion of underground mines. Preliminary to any indication of subsidence on the surface, there is usually a breaking up and sloughing of the cover into the mine opening which, in a period of time ranging from minutes to many years, progresses to the surface, This process is referred to as subsurface subsidence. In many mining operations, information regarding the process of subsurface subsidence is important, For example, if there are buildings or other improvements on the surface, or if the direction of the subsurface subsidence might threaten other underground workings--such as shafts--or if the subsidence might be progressing in a direction which would fall outside the anticipated subsidence limits, the problem could assume special significance.

Jan 1, 1961

By Edward J. Murphy

A comparative study has been made by the Bureau of Mines of several analytical methods for determining carbon monoxide and nitrogen oxides in toxic gases produced by the detonation of explosives. Laboratory and field methods and detector-tube devices are described. Analytical results are compared, and reliability of the various methods is discussed. INTRODUCTION In all underground mining there is ever-present danger to persons from possible overexposure to carbon monoxide and nitrogen oxides created by explosives or blasting agents. These health hazards, recognized for many years, led to the early establishment by the Bureau of Mines of specific requirements regarding fumes generated by explosives authorized for use in underground coal mines in the United States.3

Jan 1, 1961

By K. E. Tame

A resume of the history and state of the art of physical beneficiation of uranium ores is presented along with a detailed description of research on concentration of uranium ores by attrition grinding. The information on flotation, gravity concentration, electronic sorting, and selective grinding was gathered to complement the study of attrition grinding methods. Both dry and wet grinding procedures were investigated as potential methods of upgrading a variety of ore types, ranging in grade from 0.02 to 0.42 percent U308. A Mardun4 disintegrator that employs high-speed rotating paddles in a cylindrical shell lined with interrupter bars was used in most of the dry grinding studies. Attrition scrubbing devices, which impart a violent mixing or attritioning action to ore pulps, and cylindrical mills, employing rods or punchings as grinding media, were used in the wet grinding tests.

Jan 1, 1961

By Charles Prasky

The objective of this investigation by the Bureau of Mines was to determine the response to sulfatization of diverse low-grade manganiferous materials in the iron formation of the Cuyuna district. In line with this objective a bench-scale sulfatizing procedure was developed that was less expensive and more rapid than pilot-plant methods. Samples from the central and south- western parts of the North range were tested. Results of evaluating a total of 46 pelletized samples, originating in areas with an estimated potential resource of 94 million long tons with a manganese content of 7 percent, indicates that approximately 87 percent of the manganese may be recovered as a synthetic manganese ore. This is equivalent to more than 12 million long tons of a metallurgical-grade ore, containing 46 percent manganese. It is anticipated that a premium product, containing over 50 percent manganese, may be obtained by sulfatizing procedures. This report is part of a continuing investigation5 6 of Cuyuna iron range manganese deposits in Crow Wing County, Minn. Lewis and coworkers describe the manganiferous iron formation in the bedrock of the Cuyuna district and include a description of a high-temperature differential sulfatizing process for recovering a ferrograde manganese product. The low-grade manganiferous

Jan 1, 1961

By Harry R. Nicholls

A simple economical method has been developed for determining the in situ longitudinal and shear velocities in rock from which its elastic constants can be calculated. By detonating small charges of high explosives in shallow drill holes near a free surface, both longitudinal and shear waves were generated simultaneously. Accelerometers and velocity gages mounted to the rock surface were used to record the arrival time for both waves over travel path lengths from 50 to 450 feet, Measurements were made in two rock types. From the arrival time measurements, the longitudinal and shear wave velocities were calculated. From these velocities and the density of the rock, the elastic constants were calculated. The dynamic elastic constants of drill core samples of the two rock types were determined in the laboratory by the resonant-frequency method, The lab- oratory and in situ elastic constants are compared and significant differences noted. In general, there is less spread in the in situ data than in the laboratory data, and Poisson's ratio does not fall outside the theoretical limits for the in situ data as is often the case for laboratory-determined elastic constants.

Jan 1, 1961

By H. E. Peterson

Rhenium occurs in very small quantities (12).4 In order for the Federal Bureau of Mines to conduct an investigation of rhenium sources and methods of extraction, it was necessary to devise improved techniques for detecting and measuring minute quantities of the metal. A modification of the procedure of Malouf and White (46) was developed which can be used to detect rhenium in concentrations as small as 0.1 part per million and can be used to measure quantities of 1.0 part per million. It can be used for the analysis of siliceous and calcareous ores, of molybdenite concentrates, of fumes, of flue dusts, and of other metallurgical products. Development of the method involved devising an amine extraction procedure for separating rhenium from all interfering elements except tungsten and a selective distillation procedure for separating rhenium from tungsten. Adoption of these separation procedures permits use of large samples and precise determination of rhenium by colorimetric analysis of the thiocyanate complex of rhenium by means of a spectrophotometer.

Jan 1, 1961

By Charles B. Kenaban

The possibility of using ultrasonic energy as a tool to improve the electrolytic deposition of copper and zinc from several electrolytes was investigated by the Federal Bureau of Mines. Sound with frequencies of 20, 26, 38, and 400 kilocycles per second and acoustical intensities of 0.25 to 1.5 watts per square centimeter was employed. Measurements of cell voltage, anode and cathode current efficiencies, and electrode potentials were made at various current densities. Effects of ultrasonics on the quality of the deposit and on anode corrosion also was noted. In the electrolytic recovery of copper from an acid copper sulfate solution at 50° C., adherent, well-consolidated deposits are normally obtained up to a current density of 30 amperes per square foot. As the current density is increased above this value, the deposits normally become progressively more spongy and less adherent. Ultrasonic irradiation resulted in adherent and well-consolidated deposits at current densities up to 300 amperes per square foot. Radiation also produced smaller grain size and preferred orientation of the copper crystals. In addition, radiation caused as much as 3-volt decreases in cell voltages at the higher current densities. These decreases were caused chiefly by depolarization of the anode, although small depolarization effects were also noted at the cathode. Radiation apparently did not greatly affect cathode-current efficiencies, but prevented excessive anode corrosion at the higher current densities and resulted in more uniform corrosion. Ultrasonic radiation at a frequency of 400 kilocycles per second was not as effective as radiation at the lower frequencies. Circulation of the electrolyte at rates up to 5 percent of the cell capacity per minute did not produce results comparable to those effected by ultrasonic radiation. Rapid rotation of the cathode up to 1,800 revolutions per minute gave results approaching those obtained with ultrasonics.

Jan 1, 1961

By K. K. Kershner

This report describes an investigation by the Bureau of Mines designed to provide background data for extending and improving the applications of chlorine metallurgy in extracting metals from ores. Optimum conditions are given tor chloridizing galena, sphalerite, and chalcocite by contact with chlorine gas. Petrographic and chemical analyses of the sulfides used in the experiments are listed. Graphs are furnished showing the extent of chloridization of each metal sulfide over the temperature range of the observations. In each case, the first tests were made with the reaction chamber at room temperature. This temperature was increased by regular increments in succeeding tests until the temperature was reached at which quantitative conversion of the sulfide to chloride was observed. The data are also plotted for screen-size fractions of the sulfide minerals investigated. Data show that the extent of metal chloride formation was affected by chloridization time, particle size of the sample, and usually, the temperature of the reaction chamber. At 300° to 400° C. an anomaly was noted for both galena and sphalerite. The temperature at which this anomaly was observed varied according to the particle size of the mineral. Comparisons are made between the chloridizing characteristics of the mineral sulfides and their chemically prepared counterparts.

Jan 1, 1961