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By B. D. Nash

The object of this research was to investigate the technical feasibility of preparing chromium metal by the thermal decomposition of bisbenzene chromium. Bisbenzene chromium, a pi-bonded sandwich type organometallic compound, was thermally decomposed under reduced pressure to form a metal plate on a heated substrate. Metal recovery was close to 100 percent of theoretical, with deposition rates up to 20.8 mg/hr/cm2. Metal purity was dependent not only upon the purity of the starting material, but also upon the sublimation rate of bisbenzene chromium. Total detectable metallic impurities ranged from a low of 18 ppm to several hundred ppm. In general, metallic impurities were less than 100 ppm. Carbon, the major nonmetallic impurity, ranged from less than 0.3 percent to more than 10 percent. The carbon contamination is most likely a result of the decomposition of the organic portion of bisbenzene chromium. An unusual property of some of the deposits was their outstanding corrosion resistance. Unlike pure electrolytic chromium, which dissolves readily, these deposits were insoluble in hot mineral acids.

Jan 1, 1968

By L. S. Harner

This paper which describes the milling practice at the Golden Cycle mill is one of a series of similar papers being prepared by the United States Bureau of Mines. The mill of the Golden Cycle Corporation, formerly known as the Golden Cycle Mining and Reduction Co., is located at Colorado Springs, Colorado, and has been operated since 1907. It is now and has been from its inception almost exclusively a custom mill.

Jan 1, 1933

By K. E. Tame

The Bureau of Mines is studying possible modifications in conventional ore-processing methods that will confine and permit controlled disposal of radioactive liquid wastes. Stream and ground water pollution from radio-active nuclides, principally radium 226 and thorium 230, in liquid wastes from uranium mills can be minimized by reusing the waste solution within the mill. Such reuse of waste solution in an acid leach-resin-in-pulp flowsheet was investigated in the laboratory. The process consists of acid leaching for dissolution of the uranium, sand-slime separation and countercurrent decantation washing for recovery of a pregnant slime slurry, and the use of ion-exchange resin for recovery of uranium from the slurry. Reuse of clarified barren effluent for washing in the simulated mill circuit was carried through 55 cycles. Dissolution of uranium from the ore averaged 97.5 percent. Washing efficiency of 99.9 percent was attained when using 4.35 volume tons4 of combined barren effluent and makeup water per ton of ore. Absorption of uranium from the pregnant slime slurry by an ion-exchange resin averaged over 99.9 percent.

Jan 1, 1962

By L. F. Heising

Ten composite samples of Mesabi Range nonmagnetic taconite from the Hibbing, Minn., area were evaluated by flotation and by reduction roasting-magnetic separation to determine their potential as a future source of iron are. Only one of the composites yielded concentrates that could be considered marketable, using as a criterion a 10-to-1 iron-to-silica ratio. Cursory petrographic examinations of all 10 composited samples and a detailed mineralogical study on 1 sample suggest that unfavorable mineralogical associations between iron and gangue minerals are responsible for their poor beneficiation characteristics.

Jan 1, 1967

This report describes the new Bureau of Mines Core Repository System (CORES) and presents the methods for selecting, processing, and storing physical samples and descriptive data for future reference by earth scientists. The system preserves splits of chip samples and longitudinally sliced segments of core. A records retrieval system provides for storage of data on microfilm and magnetic tapes and uses the keysort parameters of location and commodity for the identification of data.

Jan 1, 1978

By James H. Gary

Data regarding the composition and physical properties of Florida land-pebble phosphate-waste slime are presented, and the feasibility of dewatering and beneficiating the slime by several different methods is discussed. Chemical analyses, electron micrographs, and X-ray diffraction data showed that principal constituents of the slime included quartz, attapulgite, and flaorapatite. Viscosity of the slime changed with pH; thixotropic, Newtonian, and rheopectic states were observed as the pH increased. Use of various flocculating agents was not effective in improving thickening properties of the slime. Dewatering tests using pressure filtration showed that temperature influenced the filtration rate more than pressure; the filtration rate at 165° C was tenfold that at room temperature. Selective flotation of the slime, using two different processes, gave promising results. About 25 pct of the phosphate was recovered in a concentrate assaying 31 pct P205, Other tests demonstrated that the slime could be successfully fractionated at 20-microns using a hydrocyclone. In hydrometallurgical tests about 80 pct of the phosphorus and alumina were chemically extracted from the slime using sulfuric acid. Limited bacteriological studies made of the slime showed that several types of microorganisms were present and grew in the material despite the presence of fluorine-bearing minerals.

Jan 1, 1963

By John Durkin

A computer model has been generated to evaluate speech intelligibility of individuals wearing conventional and electronic hearing protectors. For speakers talking at normal levels in noise levels of 65 db(Lp) or less, it was found that conventional hearing protectors significantly reduced speech intelligibility. Under the same conditions, electronic protectors provided scores equal to those for the unprotected individuals while providing protection from high noise levels. Therefore, electronic hearing protection is valuable in areas where high noise level is intermittent.

Jan 1, 1979

By Michael T. Nigbor

The Bureau of Mines assisted the Rocky Mountain Energy Co. in a pilot-scale in situ leaching experiment at Casper, Wyo., to determine if sulfuric acid can be used as a cost-effective alternative lixiviant (leachant) for uranium in situ leaching. This experiment, which lasted more than 2 years, is the first fully documented pilot-scale operation in which the leaching-restoration cycle was completed using sulfuric acid instead of the more common carbonate-bicarbonate leachant This report describes activities at the experimental site, presents extensive geochemical data from startup to site restoration, compares laboratory and field experiments, and discusses the environmental aspects of acid leaching. The data showed that sulfuric acid is apparently an effective leaching solution. Three to five grams of acid per liter of ground water resulted in a production solution grade of 80 to 100 ppm uranium. Restoration was successful, but required extended flushing. The pH was the last chemical parameterto return to baseline, requiring about 350 days. This was longer than was predicted in laboratory simulations. The data also showed that mobilization of toxic elements such as selenium, arsenic, radium, thorium, and molybdenum stayed within reasonable limits and quickly fell back to preleach concentrations during restoration.

Jan 1, 1982

By L. G. Marshall

This report, describing the mining method of the Dresser Trap Rock Co., Dresser, Wis., is one of a series published by the Bureau of Mines on mining methods, performance, and costs at mining operations throughout the United States. SUMMARY Dresser, in Polk County, is 3 miles south of St. Croix Falls, Wis. Company operations are about 1 mile north of the townsite. The mine has been in [peration] since 1914 and under the present ownership since 1949.

Jan 1, 1959

By James V. Kelly

During the winter of 1946 and the spring of 1947, the Bureau of Mines conducted an investigation and drilling program in the vicinity of the village of Fairplay, Wis. Fifteen diamond drill holes totaling 2,457.6 feet of bore were completed. This work was part of a general study of the zinc-producing area of southwestern Wisconsin and had the particular purpose of investigating a structural trend, determined by the Federal Geological Survey, in an area some distance from known ore bodies or active mines.

Jan 1, 1948

By John B. Goodman

This report summarizes the work done by the Koppers Company, Incorporated, in cooperation with the Bureau of Mines on the commercial evaluation of the primary low-temperature tars produced from Texas lignite in the Rockdale, Tex., plant of the Aluminum Company of America in conjunction with the Texas Power and Light Company. The interest of the Bureau of Mines in this project is twofold. First, through its cooperative agreement with the Texas Power and Light Company the Bureau has assisted in the technical design and practical operation of the prototype, externally heated, entrained-state carbonizer for producing char for electric-power production and for primary low-temperature tar. Second, the first successful operation of the prototype carbonizers employing the Bureau of Mines-Parry process on lignitic coal in 1953-54 led to the production of large quantities of primary lignitic tar, concerning which too little was known or had heretofore been published in this country.

Jan 1, 1959

By Lawrence G. Houk

Monazite sand is the only commercial source of cerium, other rare-earth metals and thorium. Although used in rather small quantities, it is essential to many industries. The United Unites is entirely dependent upon British India and Brazil for its supplies. Monazite sand or sand imported under the tariff classification for monazite was shipped to the United States in greater quantities, in 1940 than ever before. About 75 percent of our imports was from British India and most of the remainder from Brazil. If need be, Brazilian production can be expanded to supply all of our essential requirements, and the theater of war expands in the Pacific Brazil may supersede India as the principal source. PHYSICAL PROPERTIES The mineral monazite is generally honey yellow or may vary from greenish yellow to clove brown. The grains are small and resinous in luster, and range from subtranslucent to opaque. The specific gravity varies

Jan 1, 1943

By R. D. Leitch

Spontaneous firing of coal during storage end even during shipment has long been a serious problem, especially in some regions and with some coals, and methods for preventing such firing have been investigated at intervals for more than 70 years. Spontaneous or other firing of coal waste, either outside or inside mines, has also been a problem probably for as long as mining has been practiced extensively. Much trouble has been caused by such fires, and much money has been spent in attempts to extinguish them. It is known generally that surface waste banks in bituminous-coal fields are very likely to take fire sooner or later, but it is not known so generally that anthracite refuse-bark fires also are common and that at least some of them are more serious in their effect and results than being regarded merely as a nuisance. There surface refuse fires probably would have attracted much more than local attention long ago had it not been that they usually cause no more serious trouble than air pollution. A few supposedly effective methods of preventing or extinguishing spontaneous fires have been reported rather recently. Unless one or more of these prove to be widely applicable, methods of solving these problems are no more certain today than they have been for many years.

Jan 1, 1940

By Donald F. Reed

In its investigation of old, abandoned, lead-zinc mines at which records of operations are not available, in 1914 the Bureau of Mines dug surface trenches anti', in 1947 It diamond-drilled three holes at the Albright Farm deposit in Sinking Valley. Some good lead-zinc ore had been extracted from veins in dolomitic limestone during the time of the American Revolution and as late as 1870. Since that time the only activity was sporadic prospecting and developing. Thu Bureau of Mines disclosed two additional veins by surface trenching, but diamond drilling failed to find significant lead-zinc mineralization.

Jan 1, 1949

By Daniel T. Rogers

The Bureau of Mines, in its alumina miniplant project to investigate alumina recovery from domestic, non bauxitic ores, has conducted research on the use of a hydrochloric acid leaching, gas sparging crystallization technology. An important element of this research is the efficient separation of undissolved, siliceous residue from AICI3 -bearing leach liquors by continuous, horizontal, countercurrent vacuum belt filtration. In an effort to calculate material balances quickly and to predict material balances based on different belt filtration configurations, the perfect-mixing-cells-in-series model (PMCS) for calculating material balances around belt filters was used. Because of the porous nature of the solids, the model produced erroneous material balances. Therefore a reliable model, the shrinking voids model, was developed postulating the presence of an unwashable voids liquor volume that decreases with decreasing liquor AICI3 concentration. This volume decrease postulation is equivalent to assuming that dilute liquors flow more freely, causing more voids liquor volume to become washable. Least-squares based computer programs are provided, which are useful not only in producing material balances from plant data but also in predicting balances for untested configurations using the same feed materials.

Jan 1, 1982

By K. L. Rubow

"IntroductionAir sampling for airborne contaminants requires a system for moving air, a collection method, and a procedure to determine the quantity of contaminant collected. Because occupational exposure limits and air quality standards frequently are expressed in terms of concentrations, a method of determining the volume of air sampled is also needed. The four principal components in a sampling train are shown in Figure 12-1. The inlet admits the air sample into the train; the collector(s) separates the gas, vapor, or particles from the air; the flowmeter measures the rate or total quantity of air sampled; and the pump (air mover) provides the suction required to draw an air sample through the train. Inlet sampling considerations are discussed in Chapter 21. Various types of collectors are described in subsequent chapters. Flowmeters are discussed in Chapter 7.This chapter will describe the air mover portion of the sampling train and air sampling systems that contain three or four components in a convenient package. The chapter consists of two parts. The first part contains a brief description of the different types of air movers and air sampling systems. The second part consists of tables and figures showing detailed information on a wide variety of commercially available air movers and sampling systems. ient size is filled with a liquid in which the suspected contaminant is insoluble. When the liquid is allowed to escape from the vessel, it is replaced by air from the atmosphere to be sampled. Such an air sample is an integrated sample rather than an instantaneous sample because the mass of fluid requires a finite time to empty. In fact, by employing a large vessel with controlled drainage, this method can be used to move air at low flow rates through a sample collector for extended intervals. Additional discussion of this method can be found in Chapter 17."

Dec 1, 1996

By J. B. Gayle

A half-ton experimental coke oven was installed at the Southern Experiment Station, Tuscaloosa, Ala., in 1948. Designated as the Tuscaloosa oven, this unit features a 17-inch carbonizing chamber, globar heating elements, and silica-brick walls designed to simulate as closely as possible the carbonizing conditions for commercial, slot-type ovens. The reasons for constructing an oven of this Size, the details of the design, and the operating characteristics of the oven have been given in previous publications.3/4 The present report deals with the reproducibility of test-oven data and the effects of variations in flue temperature on the physical properties of the cokes produced. Also included are the results of 2,400° carbonizing tests for several coals and coal blends not included in the earlier reports.

Jan 1, 1955

By Warren D. Longwill

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Jan 1, 1981

By H. A. Schrecengost, H. R. Gil, Alfred Clarkson, E. H. McCleary

Much has been written and many discussions have been held concerning the prevention of accidents in coal mines , and considerable progress has been made in eliminating hazards to the health and safety of underground workmen . Although much progress has been made in the reduction of injury rates in the Pennsylvania anthracite field , the injury rates for the anthracite mines of Pennsylvania are generally higher than the average for coal mines in the United States as a whole , because the mining conditions , including the safety problems , in the Pennsylvania anthracite fields are more complex than in other coal fields of the United States . Several factors contribute to this extremely difficult problem , among which are : Multiple - vein mining , steeply pitching measures , folds or faults , hard smooth floors underneath the veins , and the remining or reclaiming of pillars in severely crushed , broken ground . In the early days of the Pennsylvania anthracite industry , only the more productive veins were mined , and this resulted in bypassing those veins that were relatively thin and those containing considerable proportions of impurities . However , the development of modern coal - preparation equipment , improved marketing conditions , and the adoption of mechanical equipment , such as the various types of conveyors and scraper loaders , have made possible the recovery of the thinner and poorer veins . Furthermore , in the early days , little or no attempt was made to recover the coal pillars , usually owing to the great amount of virgin coal available . Consequently , much of the anthracite produced within the last few years has been recovered by second and third mining and frequently by fourth mining - in areas where operations had been suspended for many years . In such areas , the coal veins and intervening strata are usually crushed as the result of gradual subsidence , which intensifies the hazards incidental to roof control , haulage , ventilation , and mine gases . Moreover , the use of coal - cutting equipment is not practicable in most anthracite mines because of. the inclination of the veins and because , in crushed -ground areas , the faces must be advanced slowly and for short distances at a time to permit the erection of timber sets and the placing of forepoles to support the roof and sides . Thus , the slow process of mining brought about by these conditions has resulted in the production of only 0.424 ton of anthracite for each man- hour worked , as compared with 0.753 ton? for each man - hour worked at other coal mines in the United States . A summary contained in Bulletin 462,8/ a publication of the Federal Bureau of Mines , reveals that the rate of fatal injuries in the Pennsylvania anthracite industry was improved from 13.47 deaths per million tons produced in 1870 to 3.88 deaths per million tons mined in 1942. During the period March 16 , 1942 to January 1 , 1947 , the fatality rate was reduced from 3.88 to 2.87 deaths for each million tons mined . On the million man-hour basis , the rate of fatal injuries was reduced from 1.643 to 1.130 and the nonfatalinjury rate was lowered from 119.01 to 83.12 during the same period . The improvements made in both the fatal- and nonfatal - injury rates have required the cooperation of the workmen , the mining companies , and the State and Federal inspection departments . Many individual mines and companies have achieved commendable safety records which contributed greatly to the over - all average for the industry , particularly during the 1942-47 period . One of the most outstanding of these is the Continental mine of the Continental -Archbald Coal Co. , a member of the Moffat Co. Interests .

Jun 1, 1948

By K. P. V. Lei

The Bureau of Mines investigated molten salt electrorefining 'n helium atmosphere cells as a means for the production of ductile vanadium. 'Electrolytes composed of NaCl-VCl2, LiCl-NaCl-VCl2, BaCl2-KCl-NaCl-VCl2 KCl-LiCl-VCl2, and CaCl2-NaCl-VCl2 were tested. Two electrolytes, KCl-LiCl-VCl2 and CaCl2-NaCl-VC12, were selected for laboratory-scale production tests. A molten salt electrorefining process was developed for the production of ductile 99.6 percent vanadium from a commercial 90-percent grade. Using the CaCl2-NaCl-VC12 electrolyte, an 87-percent recovery of ductile vanadium was made; an 85-percent recovery was made with the KCl-LiCl-VCl2 electrolyte.

Jan 1, 1967